includes conveyor systems being not full enclosed and slotted chutes from the conveyor to the ground level were not equipped;. 4) Overburden ...... apron color.
RISK ASSESSMENT STUDY FOR STORAGE EXPLOSIVE
By
ABDUL RAHMAN MAHMUD
Thesis Submitted to the School of Graduate Studies, Universiti Putra Malaysia, in Fulfilment of the Requirements for the Master of Environmental Engineering
All material contained within the thesis, including without limitation text, logos, icons, photographs and all other artwork, is copyright material of Universiti Putra Malaysia unless otherwise stated. Use may be made of any material contained within the thesis for non-commercial purposes from the copyright holder. Commercial use of material may only be made with the express, prior, written permission of Universiti Putra Malaysia.
Copyright © Universiti Putra Malaysia
ii
CHAPTER 1 “A safe system of work is a formal procedure which results from systematic examination of a task in order to identify all the hazards. It defines safe methods to ensure that hazards are eliminated or risk minimized”
CHAPTER 1
1.0 INTRODUCTION
Explosive is defined as substances have highly exothermic chemical reactions that produce expanding gases. It is first made by Islamic chemists Jabir Ibn Hayan, more than one thousand years ago when they discovered mixtures of saltpeter (KNO3) and sulfur could be detonated. The major used of explosive has been in warfare it is available in variety types of explosives such as bombs, explosive shells, torpedoes and missile warheads.
Nowadays explosive is not only used in warfare but it is also widely be used in mining and quarrying industries. Explosives are sales as commercials product for quarrying and mining purposes. Explosives used to break the rocks where the holes are drilled in the rocks and filled with any variety types of explosives. The explosive then detonated either electrically or with special explosives cord.
In Malaysia there has been rapidly increasing usage in amount of explosives due to the widely expansion in quarrying and mining industry. During the 2000 census it was noted were 340 operating quarries and 52 mining operations producing 56.2 million tones of material worth of RM 1.73 million. Quarrying and mining are involved with high risk activities such as blasting and drilling. The competent operators with experience and skill are needed in conducting blasting operation.
Explosive should be handled and stored in the proper manner to avoid from any adverse event occur. Explosives usually stored in the storage where safely procedures are given high attention. Fire and explosion are the two major incidents which can occur in the storage explosives. Improper handling found as the major causes in contributing the fire and explosion to occur.
Due of that issues, the need for risk assessment study for storage explosive or magazine in quarry areas has become exceedingly critical due to the increasing on the number of quarry in Malaysia. Moreover the potential damage has been magnified by the proximity of many such operations have densely populated areas.
The need for risk assessment study concerning the application of hazardous and toxic materials has becomes more important in recent years. It has been found that in many cases risk assessment study of handling hazardous and toxic materials will show the storage area has the greater potential for risk to the public. This is because of the much larger amount of hazardous material usually found in storage compared with process areas, although process areas have accidents more often then storage areas.
Accidents such as at Bhopal, in India 1984 where methyl isocynate escaped from a storage facility causing many deaths, have left the impression on the general public that storage of hazardous and toxic materials is extremely dangerous to the public.
In Malaysia, the fire and explosion incident at the Bright Sparklers Sdn. Bhd. Factory at Kg. Baru Sungai Buloh on 7 May 1991 has revealed many shortcomings and the lack of understanding in handling the explosives materials.
Explosion in the storage explosive will associates three major impacts, which include noise, vibration and blast wave. The noise will affect to human health such as permanent hearing damage, vibration and blast wave will affect damage to the environment surrounding such as building, road, railways and fatalities.
1.1 Scope of study
The research is focus on the risk assessment study for storage explosive towards emphasizes on the storage explosive in quarry. The research firstly, looks on the development of quarrying industries in Malaysia, which includes the statistical data of quarry all over the Malaysia.
The study then goes on to look the environmental problems that associated from the quarry industries. The study then emphasized on the types of explosives used for blasting operation in quarry site.
Application and handling procedure for storage explosive will also be identified. The final parts of this research is emphasis on the risk assessment study for storage explosive. Kimanis Quarry Sdn Bhd located in Papar, Sabah chosen for this research.
Risk assessment includes the identification of hazards and quantification of the risk to human fatality and ear drum rupture.
1.2 Benefit of the research
The benefit of this research can be shared between the quarry developers and public authorities concerned. The research will provide a guideline in safety by using risk assessment technique. Benefits that can be realized from this research are:
a. make use of risk assessment technique in quarry operation risk management b. provide guidelines that reflect the situation of the quarry operation c. provide suggestion for safety plan and emergency preparedness plan d. provide a prevention program.
1.3 Objectives
i.
to survey on the number of quarries in Malaysia.
ii.
to survey on the number of storage explosive in Malaysia
iii.
to identify the types of explosive used in quarries.
iv.
to identify the application and handling procedure of storage explosive (magazine).
v.
to identify the land use around storage explosive and design (magazine).
vi.
risk assessment study for storage explosive (magazine)
CHAPTER 2 Safety is a function of management ….………an accident is a failure to management
2.1
AN INTRODUCTION TO RISK ASSESSMENT
Constantly increasing public concern and interest in the environmental phenomena drives the need for transparent and communicated assessment procedures related to detectable impacts of societal developments. There is an increasing momentum for environmental protection of water, soil, air and living organism in local, national and global context. Risk assessment is taking a strong place among the tools examine and reduce potential adverse impacts to the environment.
Risk assessment is very useful to predicting potential adverse effects associated with developments proposal. It is also important in order to estimate the probability of harm occurring from the presence of dangerous conditions or materials at an installation. The output of risk assessment is most useful to provide a systematic approach, reducing the likelihood of overlooking a potential source or mechanism of pollution. In terms of national policy risk assessment will helping in order to provide guidance in developing new regulations such as for contaminated clean up and emission levels for air pollution.
Risk Assessment is defined as “a systematic approach to organizing and analyzing scientific knowledge and information for potentially hazardous activities or for substances that might pose risks under specified circumstance”. Thus fundamentally, risk depends both on the probability or frequency of an adverse outcome. Risk has similarly been defined generally as “the potential for realization of unwanted, negative
consequences of an event” (Rowe 1976:24). More quantitatively, Sage and White (1980:426) define “risk as the probability per unit time of the occurrence of a unit cost burden” and state that it “the probability per unit time of a randomly exposed individual being adversely affected by some hazardous event.” Thus risk has been defined at many different levels of detail.
More debate has occurred over acceptable level of risk than over the definition itself. The debate has occurred with respect to the process of deriving, selecting and applying acceptable levels of risk, including determination of who makes decision.
As an overall the objective of risk assessment is to estimate the level of risk associated with adverse health and safety effects of stressors or sources of those effects. Health and safety effects at the most general level encompass both human and ecological health. Stressors are the broad set of causes, such as chemicals, biological agents, and physical conditions in the guilt environment and the physical structures that pervade our everyday life.
2.1.1 Relationship of risk to other concepts
The concepts of risk is related to a number of concepts, including hazard, threat, vulnerability, uncertainty, and variability. In addition, terms related to the degree of risk such as “catastrophes”, “extreme events”, “unexpected events” and “unanticipated
events” are also common. It is important to sort out to ensure a full understanding of how they relate to risk assessment.
A “hazard” has been defined as “An act or phenomenon that has the potential to produce harm or other undesirable consequences to humans or what they value” (Stern and Fineberg (1996:215). Similarly, Merriam-Webster‘s Collegiate Dictionary (2002) defines “hazard” simply as “a source of danger”. Kaplan and Garrick illustrate the distinction between hazard and risk by considering the ocean as a hazard, and noting that the degree of risk undertaken in crossing the ocean will depend on the level of safeguards adopted.
“Threat” is another concept closely linked to risk. The definition of threat is often expressed in the context of vulnerability. “Vulnerability” is defined as “an error or a weakness in the design, implementation, or operation of a system”.
Closely related to the ideas of extreme, catastrophic, and unexpected events these are critical in linking risk assessment to risk management, since they are value laden terms that reflect human perceptions. Bier et al (1999) define “extreme events” as being extreme in terms of both their low frequency and high severity. Catastrophic risks are often distinguished from “chronic” risks, defined by Merriam-Webster as marked by long duration or frequent recurrence.” Unexpected events are obviously a significant challenge for both risk analysis and risk management.
It is also important for us to clarify the distinction between the concepts of “uncertainty” and “variability”. In particular, Kaplan (1983) distinguishes between “state of knowledge” uncertainty and “population variability.” To illustrate, in the context of equipment failure rates, state of knowledge uncertainty may refer to lack of knowledge about the average or mean failure rate across the entire population of similar items of equipment. By contrast population variability would refer to differences among the items. in the population of similar items of equipments.
2.1.3 The process of risk assessment
Fundamentally, risk assessment is form of systems analysis, and thus follows the systems approach. Haimes (1998) and Schineter (1996) lay out the steps in the systems approach as listed below:
1. Identify the problem 2. Determine the objectives and goals of the analysis 3. Become familiar with the total problem environment 4. Study the system being analyzed 5. Develop models 6. Solve the models 7. Identify various feasible solutions to the identified problem 8. Evaluate the costs and benefits of the identified solutions 9. Communicate the solutions to the client
10. Evaluate the impact of current decisions 11. Implemented the selected solution 12. Review the analysis 13. Iterate
Kaplan and Garrick (1981) state that the goal of a risk assessment is to answer three questions:
1. What can go wrong? 2. How likely is it that will happen? 3. If does happen, what are the consequences?
As general their definition of risks goes through step 7 in the above list, with remaining steps falling into the category “risk management”. However, most risk assessment in practice including the identification and evaluation of possible risk reduction measures; that is risk assessment and risk management are integrated to a much greater extent than the portrayal of the process as independent steps would lead one to believe.
The general framework presented in previous is applicable to both health and engineering risk assessment, however some of the details of the methodology differ between the two areas.
Risk Assessment includes incident identification and consequences analysis. Incident identification describes how an accident occurs. It frequently includes an analysis of the probabilities. Consequence analysis describes the expected damage. This includes loss of life damage to the environment or capital equipment and day outage.
A. Hazard identification
Process of risk assessment for engineering systems begins with hazard identification. Hazard identification is a vital part that should be taken before the next step of assessment could be conducted. In the simplest of terms, hazards can be defined as "Something that has the potential to cause harm".
Hazard identification can be performed at any stage during the initial design or ongoing operation of a process. The hazard identification can be illustrates by figure 2.1 it is shows the normal procedure for using hazards identification and risk assessments. After the description of the process available, the hazards are identified. The various scenarios by which an accident can occur are then determined.
This is followed by a concurrent study both the probability and the consequence of an accident. This information is assembled into a final risk assessment. If the risk is acceptable, then study is complete and the process is operated. If the risk is not acceptable, then the systems must be modified and procedure is restarted
System Description
Hazard Identification
Accident Probability
Accident Consequence
Risk Determination
Risk and/or hazard acceptance
Modify: Process or plant Process Operation Emergency response Other
Build and/or operate system
Figure 2.1 – Hazards identification and risk assessment procedure. Adapted from Guidelines a For Hazard Evaluation Procedures. (New York: American institute of Chemical Engineers, 1985)
Nowadays there are many methods for hazard identification, each method sometime used combined with others. The familiar methods that used for hazard identification in the risk assessment process are as follows:
1. Process hazard checklists: This is a list of items and possible problems in the process that should be checked.
2. Hazards surveys This can be as simple as an inventory of hazardous materials or it can be as detailed as the Dow indexes. The Dow indexes are formal rating systems, much like an income tax form, that provides penalties for hazards and credits for safety equipment and procedures.
3. Hazards and operability (HAZOP) studies:
This approach allows the mind to get free in a controlled environment. Various events are suggested for a specific piece of equipment with the participants determining whether and how the event could occur and whether the event creates any form of risk. A Hazard and Operability Analysis (HAZOP) is a formal systematic approach to hazard identification. It is a team-based technique, which allows the members to brainstorm opinions and viewpoints using the experience from within their own fields of expertise.
The methodology structured to ensure a thorough and consistent coverage of any system design. It examines the components of the system, and the interactions between components and explores whether deviations from the design intent are possible, and if so what the possible cause may be and the possible effects to the system and plant. It is used primarily for analysis of new system design but is just as valid, if not more so, on system modifications, re-design or fully operational systems.
Although a HAZOP may be conducted at any stage of the plant life cycle the maximum benefit will be derived during the design phase when changes are relatively easily made.
Figure 2.2 HAZOP technique
4. Fault Tree Analysis This is a method can be use to analyze top-level hazards in terms of sub, and order events, which eventually lead to individual events such as component failures that have caused the top-level event. The analysis technique in its simplest form makes use of 'And' and 'Or' logic gates to produce a tree structure. It starts at the Top Level event, and branches out through the logic gates to the base events.
Figure 2.3 Fault Tree analysis technique
Fault Tree Analysis, working outwards from Top Level Event to identify individual cause or base events. Fault tree analysis is a deductive technique, and requires a different and separate fault tree for each Top Level Event.
5. Event Tree Analysis
Event Tree Analysis complements Fault Tree Analysis in much the same way as FMEA complements HAZOP. Event Tree Analysis starts with a hazard, but instead of working backwards as in the Fault Tree, it works forward to describe all the possible subsequent events and so identify the event sequences that could lead to a variety of possible consequences.
Figure 2.4 Event Tree analysis technique
Event Tree Analysis, working from hazard events to identify consequences. The results are highly dependent on the experience and synergism of the group reviewing the process.
B. Consequences analysis
There are three stages in the quantification of the possible consequences of a hazardous event. The first stage requires a model for the attenuation of the damage causing effect (eg toxic concentration, explosion overpressure or thermal radiation) over time and distance.
The second stage utilizes knowledge of the critical levels of exposure (eg. a doseeffect relationship) to obtain a relationship between degree of damage and distance, often known as the hazard range. This may be a maximum for a particular level of damage (eg fatal injury or injury). Vulnerability model is a term used to describe the mathematical models adopted to combine these two stages of the quantification of event consequences. There may be different outcomes from a hazardous event depending on the prevailing circumstances.
In the third stages of consequence quantification, the results of the vulnerability model applied to the particular case under consideration (eg plant layout, personnel or population distribution) with probabilities allocated to variable factors such as wind direction, weather condition and occupancy.
The results are relationships between probability (conditional on the occurrence of the hazardous event) and the extent of detriment, usually expressed as the number of people suffering a specified degree of harm.
The product of the event frequencies and the conditional probabilities gives the frequency at which numbers of people would be harmed by the event. Summation of the frequencies for particular numbers of people over all events gives the overall relationship between the number of people affected and the frequency is known as societal risk. This is often expressed as F-N curve showing the cumulative frequency at which N or more people are effected.
C. Risk characterization
Risk characterization is the last step in the process of risk assessment. All the information from the previous step is used to describe or characterize the overall risks. In the other words the risk characterizations use the information from the previous step to calculate the risk.
Risk = Probability x Severity Consequences
The goal for characterize risk is to established a standard which will have broad based understanding, a strong legal precedent, and support within the technical community. A combination of information from regulations, historical precedence, and the risk statistics were used to define each criterion chosen.
The most common criteria used in risk assessment are those associated with fatal accidents. These can relate to major incidents where multiple fatalities could occur or to those incidents where the possible consequences are limited. In the case of multiple fatalities, these are often expressed as societal risk criteria to give an indication of the impact on the local population of catastrophic event.
Individual risk criteria are used where it is necessary to consider the distribution of risk. Individual risk criteria may be expressed either as peak values, to indicate where the risk is concentrated on one or very few individuals, or as average values where the risk is shared evenly amongst the exposed population.
An example of such a risk characterization is the fatal accident rate (FAR) which is usually used in assessing risk to an exposed workforce rather than to a population outside a works. Terms that have been widely used in the past are acceptable risk and criterion acceptability.
Acceptability is a much wider issue involving not just the quantitative assessment and criteria, but also the perceived risk as seen by those concerned. Perceived risk is the phenomena of an individual interpreting the magnitude of a risk against the background of his own understanding.
2.2
EXPLOSIVE
2.2.1History of explosives
Explosives is define as a substance have highly exothermic chemical reactions that produce expanding gases, were first made by Islamic chemists Jabir Ibn Hayan more than one thousand years ago when they discovered mixtures of saltpeter (KNO3) and sulfur could be detonated.
Roger Bacon (1220-1292) England, Bacon studied geometry, arithmetic, music, astronomy in France. Upon returning to England in 1247, Bacon became interested in science. His experiments using lenses and mirrors resemble modern scientific approaches. In 1257 Bacon left the University of Oxford and entered the Order of Friars Minor. His interests in the sciences continued and in 1266 Bacon wrote to Pope Clement IV proposing a science encyclopedia. Pope Clement IV misunderstood what Bacon was proposing and assumed the encyclopedia already existed. So when the Pope asked to see the encyclopedia, Bacon rapidly began work on the project.
The project was carried out in secret since Bacon's superiors opposed what he was doing. Bacon hoped to demonstrate that science had a rightful role in the university curriculum. But In 1268 Pope Clement IV died along with Bacon's chance to see the project accepted (only parts of the manuscript were ever published). While composing
the encyclopedia, Bacon became aware of the discovery by the Asian alchemists. This prompted Bacon to experiment with mixtures of saltpeter, sulfur, and a new ingredient (charcoal); Bacon had made black powder (the early form of gunpowder).
One hundred years later friar Berthold Shwarts looked into this black powder. Schwarts took a long iron tube and closed one end except for a tiny hole. He filled the tube with black powder and stuffed a small pebble in it. He touched a flame to the tiny hole and the pebble shot through the air with great speed. Schwarts had invented the "gun."
a. Nitroglycerin (NG)
Five hundred years after Berthold Schwarts invented the gun, Ascano Sobrero (Italian) mixed nitric acid and glycerin to obtain nitroglycerine an explosive so unstable that it could be detonated by the touch of a feather. One mole of nitroglycerine (227g) releases 1427 kJ upon exploding. Its volume increases from a liquid of approximately 1/4 L to gases occupying approximately 650 L.
Figure 2.5 Chemical structure reaction for production nitroglycerin
In 1845, Christian Schoenbein made nitrocellulose (guncotton) by dipping cotton in a mixture of nitric and sulfuric acids. However, the material obtained was too unstable to be used as an explosive. Major E. Schultze (1860) of the Prussian army produced a useful propellant. He nitrated small pieces of wood by placing them in nitric acid and impregnated the pieces with barium and potassium nitrates. The purpose of the latter was to provide oxygen to burn the incompletely nitrated wood.
Schultze's powder was highly successful in shotguns but was too fast for cannon or even most rifles. In 1884 a French chemist, Paul Vieille, made the first smokeless powder as it is now known. He partially dissolved nitrocellulose in a mixture of ether/alcohol, then he rolled it into sheets and cut into flakes. When the solvent evaporated, it left a hard, dense material. This product gave satisfactory results in all types of guns.
b. Dynamite
Alfred Nobel mixed nitroglycerin and silica (SiO2) forming a paste that could be safely used as an explosive he patented this material as dynamite (1867). Nobel also invented the blasting cap to provide a safe and dependable means for detonating. Nobel's original blasting cap consisted of 80% mercury fulminate [Hg(ONC)2] and 20% potassium chlorate. Blasting caps today are lead azide [Pb(N3)2] due to its greater stability when stored under hot conditions.
c. Ballistite
In 1887 Nobel introduced ballistite, 40% nitrocellulose/60% nitroglycerin blended together with diphenylamine. When cut into flakes, this made an excellent propellant and it continued in use for over 75 years. The British refused to recognize Nobel's patent and developed a number of similar products under the generic name cordite.
d. Cordite
Sir James Dewar (1842-1923) is best known for his work with low-temperature-he invented the thermos and produced both hydrogen and oxygen in liquid form. Along with Sir Frederick Abel, Dewar invented cordite (1889). This smokeless gunpowder consists of nitroglycerin, guncotton, and a petroleum substance gelatinized by addition of acetone.
2.2.2 Classification of commercial explosives
Explosives have been widely used in industrial and military activities, nowadays there are many types of explosives are design for various purposes. Explosive are classified in two major categories there are High Explosives and Low Explosives (Figure 2.6).
High explosives then divided into two groups primary explosive and secondary
explosives.
2.2.3 Low Explosives
Low explosives are defined as an explosive mixture which under any condition cannot support a detonation wave. Low explosives are also defined as a solid mixture of chemicals which burn in the absence of air, but which, when confined, can burn to deflagration.
2.2.4 High Explosives
High explosives defined as explosive, which supports a detonation wave. High explosives are also defined as an explosive substance or mixture which invariably detonates when initiated, irrespective of the ambient condition of confinement (i.e. in the open). High explosives are those materials that undergo detonation without confinement, are compounds, initiated by shock, the reaction within the product is supersonic, and has a high brisance.
1. Primary Explosives
Primary Explosive, a sensitive explosive which nearly always detonates by single ignition from such means as spark, flame, impact and other primary heat sources of appropriate magnitude. Primary explosives can detonate by the action of a relatively weak mechanical shock or by a spark. If used in the form of blasting caps (detonator), they initiate the main explosive. They are also filled in percussion caps mixed with friction agents and other components.
An initiating explosive must be highly brisant and must have a high triggering velocity. The most important primary explosives are mercury fulminate, lead azide, lead trinitroresorcinate, silver azide, diazodinitrophenol, and tetrazene, which is used as an additive in primers. Initiating charges must be transported only if they are already pressed into capsules. The latter are usually made of aluminum, and sometimes of copper, white plastic capsules are used for special purposes.
Primary explosives, have a low deflagration to detonation transition, and go from burning to detonation very quickly. They differ as to sensitivity and the shock given off. Primary explosives are reactive to different materials, care should be taken when handling primary’s that are in the natural state. Generally speaking, they will not be found in the raw form.
2. Secondary High Explosives
Secondary high explosives are those explosives which are relatively insensitive, in comparison to primary explosives and are insensitive to shock, friction, or heat. They are, however cap or booster sensitive and are classified as High Explosives. It would not be worth taking the time to discuss secondary high explosives without spending some time discussing the history and the impact that Nitroglycerin and Nobel had on the development of explosives.
a. Nitroglycerin (NG)
Nitroglycerin was first prepared late in the year 1846 or early in 1847 by the Italian chemist Ascanio Sobrero (1812 – 1888). Nitroglycerin was the first, and is still one of the most widely produced nitrate ester. It is used in dynamites, nitroglycerine is absorbed in fine wood meal or other powdered absorbent.
This process prevents the microbubbles from forming and stabilizes the liquid. The nitroglycerine is also thickened or gelantinized by the addition of a small percentage of nitrocellulose. This process assists in preventing "weeping" (exhuding) or settling out
of the absorbent material. Because settling does occur, boxes of stored nongelled dynamites are turned over at regular intervals to reverse the settling flow.
Nitroglycerin is one of the most important and most frequently used components of explosive materials, together with nitroglycol, it is the major component of gelatinous industrial explosives. In combination with nitrocellulose and stabilizers, it is the principal component of powders and solid rocket propellants.
b. Dynamite
Nobel, having discovered a way to reliably initiate nitroglycerin, knew that the extreme sensitivity and difficulty in handling the liquid were very serious problems. Dynamite and the fulminate blasting cap both resulted from Alfred Nobel’s effort to make nitroglycerin more safe and more convenient to use.
c. Ammonium Nitrate
J. R. Glauber first synthesized ammonium nitrate in 1659 by combining nitric acid and ammonium carbonate. Ammonium nitrate, which Glauber named "Nitrum Flammans", occurs in nature only rarely and then in very small amounts. Today this chemical compound has two widely recognized and diverse uses. An important fertilizer for the agricultural industry. The basic ingredient of most commercial explosives, where it serves as an oxidizer.
In 1867, two Swedish chemists, C. J. Ohlsson and J. H Norrbin, patented an explosive, called ammoniakrut, which consisted of ammonium nitrate either alone or in mixture with charcoal, sawdust, naphthalene, picric acid, nitroglycerin, or nitrobenzene. Theoretical calculations had shown that large quantities of heat and gas were given off by the explosions of these mixtures. The proportions of the materials were selected in such a manner that all of the carbon should be converted to carbon dioxide and all the hydrogen to water. Some of these explosives were difficult to ignite and to initiate, but the trouble was remedied by including some nitroglycerin in their compositions and by firing them with fulminate detonators.
They were used to some extent in Sweden. Nobel purchased the invention from his fellow-countrymen early in the 1870’s, and soon afterwards took out another patent in connection with it, but still found that the hygroscopicity of the ammonium nitrate created several problems. He was not able to deal satisfactorily with the problems until after the invention of gelatin dynamite.
1935, experimentation began on blasting with a mixture of prilled fertilizer grade ammonium nitrate (FGAN) and carbon black or cold dust at a surface coal mine in Indiana. The mixture was packaged in large tubes and was primed with 20 pound charges of dynamite. It is popularly believed that this product was developed because of publicity about the 1947 Texas City disaster in which two ships laden with ammonium nitrate fertilizer blew up. In actuality, that explosion occurred with grained AN, not prilled, and in 1947 the time was not correct for a new blasting material.
The success of the Indiana experiments was that prills had become commonly available (all fertilizer production in the US having converted to prilling by 1948), and that dry drilling of large diameter blastholes in the surface mines was becoming the norm. The person responsible for the product was Bob Akre of the Maumee Collieries, and the product was called Akremite. Within a very short period of time after the May 1955 experiment other mines began using prills mixed with common #2 diesel fuel, and the name ANFO was soon applied.
Prills denote the ammonium nitrate pellets obtained by cooling free falling droplets of the molten salt in so called prill towers. By special processing, they can be porous and capable of absorbing a certain percentage of liquid hydrocarbons. Under the same name, "Prills" also the ready made ANFO explosive marketed.
Ammonium nitrate is the most important raw material in the manufacture of industrial explosives. It serves also as constituent in rocket propellants, in the capacity of a totally gasifiable oxygen carrier.
d. ANFO (Ammonium Nitrate and Fuel Oil)
Ammonium nitrate explosives are mixtures of ammonium nitrate with carbon carries such as wood meal, oils or coal and sensitizers such as nitroglycol or TNT and dintroluene. They also may contain aluminum powder to improve the strength. Such mixtures can be cap-sensitive. The non-cap-sensitive’s are classified as blasting agents.
Mixtures of porous ammonium nitrate prills with liquid hydrocarbons, loaded uncartridged by free pouring or by means of air loaders, are extensively used under the name NAFO Blasting Agents.
2.3
THEORY OF EXPLOSION
Nowadays explosion is a major risk in activities, which deal with substances, materials, or operations that have risk of explosion. In order to conduct the risk assessment studies with respect to the risk of explosion the theory of explosion has become most important.
2.3.1 Definition
There are many researchers defined explosion in various ways. For this study numbers of texts were reviewed.
Explode: (from Latin explodere to drive off the stage by clapping -plaudere to clap) to cause to explode or burst noisily: to burst forth with sudden violence or noise from internal energy as:
(a) to undergo a rapid chemical or nuclear reaction with the production of noise heat and violent explosion of gases
(b) to burst violently because of pressure from within (Webster, 1987).
Explosion and Explosive: An explosion is a sudden expansion of matter into a much larger volume than it formerly occupied. An explosive is a substance containing a larger amount of stored energy that can be released suddenly, thereby converting the substance into compressed gases or a swarm of fragments that expand with great force or velocity (McGraw Hill, 1987).
Explosion: An explosion is a rapid expansion of gases resulting in a rapidly moving pressure of shock wave. The expansion is can be mechanical (by means of a sudden rupture of pressurized vessel), or it can be the result of a rapid chemical reaction. (Daniel A. Crowl et al Chemical Process Safety: Fundamental With Application 2nd edition, pp. 228, 2001)
2.3.2 Explosion Behavior
Explosion behavior is difficult to characterize. Many approaches to the problem have been undertaken, including theoretical, semi empirical, and empirical studies. Despites these efforts, explosion behavior still not completely understood. The summary of the important parameters is shown in table 2.1.
Parameters Significantly Affecting the Behavior of Explosions Ambient Temperature Ambient Pressure Composition of explosive material Physical properties of explosive material
Nature of ignition source: type, energy, and duration. Amount of combustible material Turbulence of combustible material Time before ignition Rate at which combustible material is released
Table 2.1 Parameters significantly affecting the behavior of explosions
An explosion results form the rapid release of energy. The energy must be sudden enough to cause a local accumulation of energy at the site of the explosion. This energy is then dissipated by a variety of mechanisms, including formation of a pressure wave, projectiles thermal radiation and acoustic energy.
Most of the explosions occur in a gas the energy causes the gas to expand rapidly, forcing back the surrounding gas and initiating a pressure wave that moves rapidly outward from the blast source. The pressure wave contains energy, which results in damage to the surroundings. A pressure wave propagating in air called a blast wave because the pressure wave is followed by a strong wind.
2.3.3 Detonation and deflagration
Explosion can be detonation or deflagration depending on the rate of energy release. The damage due to the explosion is also depending on the behavior of the explosion. Detonation defined as an explosion that the rate of reaction move greater than
the speed of sound in the unreacted medium, deflagration defined as an explosion, which rate of reaction move less than the speed of sound in the unreacted medium.
The differences between these types of explosion also can be describe by the reaction front propagates above or below the speed of sound in the unreacted gasses. For the ideal gases the sonic velocity is a function of temperature only and has a value of 344 m/s (1129 ft/s) at 20 C. fundamentally, the sonic velocity is the speed at which information is transmitted through a gas.
DETONATION
15 Peak overpressure Shock front
Reaction Front
Pressure (atm)
Ambient Pressure
0
Distance
Figure 2.7 Detonation mechanism
In a detonation, the reaction front moves at a speed greater than the speed of sound, driving the shock front immediately precede it. Both fronts move at the same speed.
DEFLAGRATION
Peak Overpressure
15 Pressure front
Reaction Front
Pressure (atm)
Ambient Pressure 0 Distance
Figure 2.8 Deflagration mechanism
In a deflagration, the reaction front moves at a speed less than the speed of sound, while the pressure front moves away from the reaction front at the speed of sound.
The pressure fronts produced by detonations and deflagration are markedly different. A detonation produces a shock front, with an abrupt pressure rise a maximum pressure of greater than 10 atm and total duration typically less than 1ms. The pressure front resulting from a deflagration is characteristically wide (many milliseconds in duration), flat (without an abrupt shock front), and with maximum pressure much lower than the maximum pressure for a detonation (typically 1 or to 2 atm).
2.3.4 Classification of explosion
Explosion can be classified as follows:
A. Physical explosion – that is, bursting of vessels, building rupture due to simply pressure, as in the case of steam boiler and air receiver explosions. Fire is not necessarily a consequence. Fire involving shock, buildings and plant ancillaries can cause physical explosions due to overheating of vessels and fireballs if the contents are flammable. One such case is termed a boiling liquid of vessels and fireballs if the contents are flammable (BLEVE).
B. Chemical Explosions of plant and vessels can arise due to exothermic reaction occurring internally. Such reaction may involve decompositions of unstable substances, polymerization of monomers or combustions of fuel-oxidant mixtures. Heating and increase of molecular number can result in a rise in pressure to the bursting point of the vessel, and explosive decompose so quickly that confinement and the development of pressure are self impose.
C. Escape of flammable fluids to subsequent combustion on encountering a source of ignition. An explosion followed by fire ensues if this occurs in a building. If it occurs in the open, the result may be a fireball (immediate ignition), a flash fire (delayed ignition) or a vapor cloud explosion (VCE).
D. Electrical explosion involve the discharge of a high voltage supply to earth. They are notable because no flammable material is involved.
2.3.5 Blast waves
Blast wave is produced by the pressure wave or shock wave from the explosion combined with subsequent wind. In other words an explosion is a process involving of a pressure discontinuity or blast wave resulting from a rapid release of energy. A pressure disturbance is generated into the surrounding medium. Air becomes heated due to its compressibility and this leads to an increase the velocity of sound, causing the front of the disturbance to steep as it travels through the air. The pressure and density of the air is increased until a peak pressure wave is developed at some nominal distance. The loading and hence the damage to nearby targets are governed by the magnitude and duration of this pressure wave.
The explosion is occur at time t0 there exists a small but finite time t1 before the shock front travels from its explosive origin to the affected location. This time, t1, is called the arrival time. At t1 the shock front has arrived and a peak overpressure is observed, immediately followed by a strong transient wind. The pressure quickly decreases to ambient pressure time t2, but the wind continues in the same direction for a short time. The time period t1 to t2 is called the shock duration.
The shock duration is the period of greatest destruction to free-standing structures, so its values are important for estimating damage. The decreasing pressure continues to drop below ambient pressure to a maximum under pressure at time t3. For most of the under pressure period from t3 to t4 the blast wind reverses direction and flows towards the explosion origin. There is some damage associated with the under pressure period, but because the maximum under pressure is only a few psi for typical explosion, the damage is much less than that of the over pressure period.
After attaining the maximum under pressure t3, the pressure will approach ambient pressure at t4. At this time the blast wind and the direct destruction have terminated.
According to Crowl et. all [8] an important consideration is how pressure measured as the blast wave passes. If the pressure transducer is at right angles to the blast waves, the overpressure measured is called the site on overpressure (sometimes called the free-field overpressure). At a fixed location, figure 2.9, the side on overpressure increases abruptly to its maximum value (peak side on overpressure) and then drops off as the blast wave passes.
If the pressure transducer placed facing toward the oncoming shock wave, then the measured pressure is the reflected overpressure. The reflected overpressure includes the side-on overpressure and the stagnation pressure. The stagnation pressure is due to deceleration of the moving gas it impacts the pressure transducer. The reflected pressure
for low side on overpressure is about twice the side-on overpressure and can reach as high as eight or more times the side on overpressure for strong shocks.
The reflected overpressure is maximum when the blast wave arrives normal to the wall or object of concern and decreases as the angles changes from normal. Blast damage is based on determination of the peak side-on overpressure resulting from the pressure wave impacting on a structure. In general, the damage is also a function of the rate pressure increase and the duration of the blast wave.
Pressure Psig
Damage
kPa
0.02
0.14
Annoying noise (137 dB if low frequency, 10-15 Hz)
0.03
0.21
Occasional breaking of large glass windows already under strain.
0.04
0.28
Loud noise (143 dB) sonic boom, glass failure
0.1
0.69
Breakage of small windows under strain
0.15
1.03
Typical pressure for glass breakage
0.3
2.07
“safe distance” (probability 0.95 of no serious damage below this value); projectile limit; some damage to house ceilings; 10% windows glass break.
0.4
2.76
Limited minor structural damage
0.5-1.0
3.4-6.9
Large and small windows usually shatter, occasional damage to windows frames.
0.7
4.8
Minor damages to house structures
1.0
6.9
Partial demolition of houses, made uninhabitable
1-2
6.9-13.8
Corrugated
asbestos
aluminium
panels, fastening fails, follow by buckling;
shatters,
corrugated
steel
or
woods panel (standard housing), fastening fails, panels blow in 1.3
9
Steel frame clad building slightly distorted
2
13.8
Partial collapse of walls and roofs of houses
2-3
13.8-20.7
Concrete or cinder block walls, not reinforced, shatter
2.3
15.8
Lower limit of structural
2.5
17.2
50% destruction of brickwork of houses
3
20.7
Heavy machine (3000lb) in industrial building suffer little damage; steel frame building distort and pull away from foundations
3-4
20.7-27.6
Frameless, self training steel panel buildings demolished, rupture of oil storage tanks
4
27.6
Cladding of light industrial building ruptures
5
34.5
Wooden utility poles snap; tall hydraulic presses (40 000lb) in building slightly damaged
5-7
34.5-48.2
Nearly complete destruction of houses
7
48.2
Loaded train wagons overturned
7-8
48.2-55.1
Brick panels, 8-12, not reinforced, fail by shearing or flexure
9
62.0
Loaded train boxcars completely demolished
10
68.9
Probable total destructions of buildings, heavy machine tools (7000lb) moved and badly damaged, very heavy machine tools (12000lb)
300
2068
Limit crater lip
Table 2.2 Damage estimates for common structures based on overpressure.
2.3.6 TNT Equivalency
Beshara [12] pointed out that most of the data pertaining to explosions deal with the use of TNT explosive, consequently the data for any other explosive needs to be related to that of an equivalent explosion. This is done by relating some measure of the explosive energy produced with that produced by an equivalent amount of TNT. The equivalency of material compared to TNT may be affected by other factors such as the material shape (flat, square), the number of explosive items, explosive confinement, nature of source and the pressure being considered [13]. The effects of the energy output of explosive material, relative to that of TNT, can be expressed as a function of the heat of detonation as follows:
WTNT = (Hexp/ / HTNT)x Wexp
Where WTNT is the equivalent TNT charge weight, HTNT is the heat of detonation of TNT, and Hexp is the heat of detonation of the explosive. A typical value of explosion TNT is 1120cal/g = 4686 kJ/kg =2016 Btu/lb. The heat of combustion for the flammable gas can be used in place of the energy of explosion for combustible gas.
The TNT equivalency method also uses an overpressure curve that applies to point source detonations of TNT. Vapor cloud explosion (VCEs) are explosions that occur because of the release of flammable vapor over a large volume and are most commonly deflagrations. In addition, the method is unable to consider the effects of
flame speed acceleration resulting from confinement. As a result, the overpressure curve of TNT tends to over predict the overpressure near the VCE and to under predict at distances away from the VCE.
2.3.7 Blast scaling law
Characteristics of the blast wave generated in an explosion depend both on the explosive energy release and on the nature of the medium through which the blast propagates. These properties are measured under controlled conditions in experiments (providing a reference set of explosion data). The most common form of blast scaling is the cube root scaling law. This law states that when two charges of the same explosive geometry, but of different size are detonated in the same atmosphere, the shock wave produced are similar in nature at the same scaled distances. The scaled distance or the proximity factor Z, is defined as
Z = R / (WTNT 1/3) Where R is the distance from the center of the explosion to a given location and W is the weight of the explosive. In addition to this, the explosive yield factor is ., is useful in blast scaling.
Experiments with explosives have demonstrated that the overpressure can be estimated using an equivalent mass of TNT denoted WTNT, and distance from the ground – zero point explosion, denoted R. correlation for the scaled overpressure ps is given by
ps = po / pa’ where ps is the scaled overpressure (unitless) po is the peak side –on pressure, and pa is the ambient pressure
Figure 2.10 is valid only for TNT explosions on a flat surface. For explosion occurring in the open air, well above the ground, the resulting overpressure from figure 2.10 are multiplied by 0.5. Most explosions occurring in chemical are considered to originate on the ground. Data in figure 2.10 are also can be represented by the empirical equation below
ps= po/pa = [1616[1+ (Z/4.5) 2 ]] / [ (1+(Z/0.048))1/2 x (1+(Z/0.32))1/2 x (1+(Z/0.048))1/2 ]
2.4
EXPLOSION INCIDENTS IN CHEMICAL PROCESS AND EXPLOSIVES INDUSTRIES
There has been a rapid growth of industries over the past three decades especially in oil, gas and petrochemical all over the country. Like other industries nations these industries are huge, modern, and more sophisticated types of industries utilizing complex process operating at high pressure and temperature, producing continuously and using hazardous substance. Major industries accidents had happened in the past and are likely to occur again in future if no initial attention and precautions taken to manage and control these installations.
Table 2.3: Major industrial accidents in Asia Hazardous Substance Methyl isocyanate Gunpowder Liquefied petroleum gas (LPG) Fireworks Ammonia Flammable chemical Gunpowder Reaction between hydrosulphate & sodium sulphide Ehhene Potassium chloride Petrol Carbonyl chloride (phosgene)
Deaths
Injuries
Place and date of accident
> 2 500 9 35 40 7 5 63 15
> 200 000 59 15 60 30 >200 52 25
Bhopal, India 1984 Seoul, republic Korea, 1987 Nagothane, India, 1990 Sungei Buloh, Malaysia, 1991 Dhaka, Bangladesh, 1991 Bangkok, Thailand,1991 Hubei, China, 1993 Shenzen, China, 1993
9 35 7 1
6 104 12 101
Beijing, China, 1997 Chiang Mai, Thailand, 1999 Chonburi, Thailand, 1999 Rayong, Thailand, 2000
2.4.1 Malaysia
Bright Sparklers Firework explosion in 1991 in Sg. Buloh and Tiram Kimia Depot Chemical explosion 1992 are two examples in Malaysia with the major explosion incidents. The incidents have shown the need for proper handling of explosive chemical during its manufacturing process. The fire and explosions incident at the Bright Sparkles Sdn. Bhd on 7 May 1991 has also revealed many shortcomings and the lack of understanding and coordination responsible for the licensing, regulating and enforcement of various law.
In 25 December 1997 explosion in Air Separation Unit in the Shell Middle Distillate Synthesis (MDS) Plant at Bintulu, Sarawak was occurred. This explosion is occurred when the combustible airborne particulates had passed the main purification section of the air separation unit. These combustibles contaminants had accumulated on the aluminium main vaporizers of the distillation column. Once hydrocarbon combustion was triggered, it led to aluminium combustion which generated heat and vaporized the cryogenic liquids and the explosion.
2.4.2 United Kingdom
A reviewed of the accidents record for explosive manufacturer and storage in UK during period 1950-1997 has been done by R. Merrifield and P.A. Moreton [8]. From the review 77 major explosives events were found, a major event a defined as one which
substantially destroys the building in which it occurs and results in projection of debris and or blast effects at a distance, so posing a hazard to persons elsewhere on the site or indeed beyond the site.
R. Merrifield and P.A. Moreton [10] has given three factors that contribute in the events to occurred, these factor includes:
1) The inherent sensitivity and Compatibility Group of the explosives substances and articles manufactured and stored.
2) The types of manufacturing and handling processes employed (which may include a number of built in engineered safeguard)
3) The managerial and procedural safeguards, of which safety culture and training and supervision of staff.
2.4.3 Mt. Wright, Canada
In 18 April 1990 in Mountain Wright Canada an incident has occurred during the transfer emulsion explosives from one truck to another. Investigations indicated that emulsion had ingresses into the hollow rotor of the pump that had been used in transfer operation. The explosion occurred after pump had been left running dry for about 10 min while the operatives took a tea break this led to a thermally-induced initiation.
2.4.4 South Africa
In 23 August 1990 in South of Africa an incident occurred during the packaging of emulsion by means of cavity pump. The explosion occurred after the operatives had over ridden a cut – out switch connected to a pressure sensor.
In 11 December 1990 in South of Africa an incident has occurred after smoke had been seen coming from the feed hopper above the pump. The building was evacuated and the explosion occurred 10 min later. Subsequent investigations revealed that emulsion had ingressed into cavities in three similar pumps, and it was thought that excessive heat may have been produced at the gland assembly, the universal joints, the rotor or the heating tape.
2.4.5 Asbest, Russia
In 1st September 1990 the catastrophic event occurred in Asbest Russia which resulted loss in 16 lives. The explosion occurred during the transfer of emulsion from a storage tank to a truck. Investigation suggested that the cause of the explosion decomposition in the holding tank.
2.4.6 Five Explosion accidents in China
Study has been done by Zhang Guoshun [11] for five major explosion events in the explosives and chemicals industries in China. The five explosions were:
1) The explosion at a TNT workshop of a chemical factory, Liaoning province, on February 9 1991 in which 17 employees died and 107 were injured.
2) The nitro-amine explosive production workshop of a chemical factory in Hubei province on June 27, 1992, which led to the deaths of 22 employees and 13 injuries.
3) An explosion in storage warehouses containing dangerous goods in Shenzhen City on August5, 1993, where 141 injured.
4) An explosion of a truck loaded with 1.05 detonators on October 23, 1994 causing 5 deaths 95 injuries.
5) An RDX explosive incident in Hunan province on January 31, 1996 in which 134 people died and 17were injured.
Though the root causes of the above accident has been concluded by Zhang Guoshun [11] the reasons as follows:
1) Operating personnel had inadequate knowledge of the safety of their jobs
2) An inadequate understanding and respect for the hazards of the materials and processes they operated
3) Training in normal and emergency operations
4) Procedures for safety activities and Enforcement both by the employer and outside regulatory bodies for violations.
From the above incidents we indicate that, fire and explosion is the major risk in chemical process and explosives industries. Improper handling found to be the major causes to induce the incidents to occur. The integration from all parties in giving commitment and attention for safety procedure with regards to the application of hazardous material is most important in avoiding the worst case from occur.
2.5
CONSEQUENCE ANALYSIS OF RISK EXPLOSION
Consequences analysis in the risk assessment is obtained to describe the expected damage to the physical surrounding and human injury. There are many types of software are available for consequence analysis. Indeed the simulation by computer can assist assessor to get easily the data and value regarding to the expected damage or injury. The results form consequences analysis can be used for emergency planning and to determine the hazard area within the facility and site operation.
2.5.1 Source models
In order to analyze the consequence, source models are an important part of the consequence modeling procedure shown in figure 2.11. Accidents begin with an incident, which usually results in the loss of contaminant of material from the process. The material has hazardous properties, which might include toxic properties and energy content.
Typical incidents might include: 1. rupture of break of a pipeline 2. a hole in a tank or pipe 3. run away reaction or fire external to vessels
Once the incident is known, source models are selected to describe how materials are discharged from the process. The source models provides a description of the rate of discharge, the total quantity discharged, and the state of discharge (that is solid, liquid, vapor, or combination). A dispersion model subsequently used to describe how the material is transported downwind and dispersed to some concentration levels.
For flammable release, fire and explosion models convert the source model information on the release into energy hazard potential, such as thermal radiation and explosion overpressures. Effect models convert these incident specific results into effects on people (injury or deaths) and structures.
Environmental impacts could also be considered, additional refinement is provided by mitigation factors such as water sprays, foam systems, and sheltering or evacuation, which tend to reduce the magnitude of potential effects in real incidents.
2.5.2 Assumption in the framework of consequence explosions
An almost universal hypothesis used in quantitative risk assessment (QRA) to model consequence explosions is to assume that all the accidental phenomena produce blast waves, which can be idealized and compared to the ideal blast waves produced by an equivalent charge of one or more solid “point” explosions. By these methods, peak overpressure P and Impulse I can be easily determined. A further simplifying assumption
consists of considering uniform blast load acting on the whole equipment, a conservative approach often used in the design criteria. This assumption is certainly acceptable when blast waves such produced by Vapor Cloud Explosion (VCE) impact either on small and medium scale equipment.
An explosion can be defined as the rapid release of energy into the atmosphere, thus generating a blast wave, which produces damages [15]. Actually, the definition extents its meaning to several different phenomena which can be categorized as condensed phase explosions (e.g explosive charges), confined explosion (dust and gas explosion within equipment and buildings), boiling liquid expansion vapor explosions (BLEVE), runaway reaction explosion, physical explosion (e.g the bursting of overfilled vessels), unconfined and partially confined vapor and gas explosion (VCE).
The observed damages are mainly related to the incidents overpressure (P) to the positive impulse (I) and to drag forces on bodies (Pd) which strongly depending body shape and orientation.
2.5.2 Model for accident propagation caused by overpressure.
Only simplified models for damage to equipment would be acceptable for quantitative risk assessment. Eisenberg et al. [16] used a simplified model to assess the damage probability of process equipment caused by blast wave. The authors defined a
probability function called “probit function” (Y) to relate equipment damage to the peak static overpressure P: Y = k1 + k2 ln(P◦) (13)
where Y is the probit for equipment damage, P◦ is expressed in Pa (pascal), k1 and k2 are the probit coefficients (k1 = − 23.8 and k2 = 2.92 as reported by Eisenberg et al. [16]).The cited “probit analysis” is a well known method to evaluate the dose effect relation for human responses to toxic substances, thermal radiation and overpressure, but can be also considered a useful statistical method to evaluate damages of equipment subjected to pressure waves in the mainframe of quantitative risk analysis. It derives from the cumulative expression for a normal Gaussian probability distribution function [17]:
where F is the probability (0 ≤ F ≤ 1), and the term u is:
where V is the independent variable or the “dose”, µ and σ are the median and the variance of the Gaussian distribution. In Eq. (14), Y is the probit unit:
Y = k◦ + ln (u) = k1 + k2 ln V
In dose response analyses, the constant k◦ is usually set to five; otherwise, Y is less than zero for F < 0.5. The model of Eisenberg [16] was based on “experimental” evaluation of equipment displacement with the subsequent deformation and breakage of connections, hence not considering the direct catastrophic failure of equipment.
The probit approach was followed also by Khan and 1Abbasi [18], who proposed a probit function similar to the equation of Eisenberg, but substituting the static overpressure with the total pressure (the sum of static and dynamic pressure). For the typical far field, low pressure blast wave produced by industrial explosion the dynamic pressure can be considered as negligible with respect to the static pressure. However, Khan and Abbasi give the same probit coefficients of Eisenberg et al. [16].
To analyze the consequence explosion to the structural the overpressure value are compared to available literature data on damage to equipment and building. The data can be found from the previous researcher or the past event.
2.5.3 Gas Explosion Modeling
Simulation modeling of Gas explosion in chemical plant has been done by Salzano et al [14]. In the studied Chemical Fluid Dynamic (CFD) code AutoReaGas and
the Multi-Energy Method have been used to evaluate the gas explosion consequences, in terms of calculated overpressure, for incident in the chemical plant. Vapor Cloud Explosion (VCE) model has been use to analysis the consequences.
The simulation succeeds in determination of the maximum overpressure in relation to the distance from the potential explosion site. However the evaluation of the effects of the generated blast wave is still lead back to the equivalence with an explosion having a point source due to a charge of TNT.
CHAPTER 3 “The concept of risk is not new, and has always been a feature of daily and activities. Risk is everywhere around us.”
CHAPTER 3
3.0 METHODOLOGY
3.1.0 Survey on the number of quarries in Malaysia
The study began with survey on the information, data, and statistic from several departments, which related with quarry industries in Malaysia. The departments are involved in the quarry industries are as follow:
1. Department of Environmental 2. Department of Mineral and Geosciences.
The sources of information found from the library from each department. The data and information regarding to the number of quarries in Malaysia found from directory listing of quarrying and mining industries.
3.2.0 Survey on the number of storage explosive in Malaysia
Since the information on the number of quarries in Malaysia found, the study moves to the next step to search the number of storage explosive in Malaysia. The study emphasis
on the number of storage explosives used in quarries. The information with regards to the number of storage explosives found from The Malaysian Royal Police Department who authorized by the government in licensing for magazine construction.
3.3.0 Identify the types of explosive used in quarries.
Blasting activities are involved with variety types of explosives, it is use to break the rock surface. This part identified the types of explosives used for blasting operation. The identification types of explosive used in quarry is carry out through observation and reviewed the EIA reports and other book references. The information from Material Safety Data Sheets (MSDS) extracted to identify specification of particular explosives.
3.4.0 Identify the handling and application procedure of storage explosive
Explosives that used in the quarry site should be handled and stored with following the right procedure. Observation and interviewed with quarry operator are the method used to identify handling procedure of storage explosive.
3.5.0 Identify the land use around storage explosive and design (Magazine)
Land use around storage explosive has been identified through study on the map. There are two map shows the quarry operation area and the surrounding area of quarry. This information is very important for consequence analysis.
3.6.0
Risk assessment study for storage explosive (Magazine)
3.6.1 The identification of hazard and failure scenarios
Identification of hazard for explosives and detonator done by study on the material safety data sheets (MSDS) and other sources from literature review. All the hazard data was extracted and summarized in the table. The quantification of failure frequencies done by breaking down and tracing each action of failure into the simples and most basic form failure.
3.6.2 Estimation of the frequency of occurrence for each failure scenario
The frequency of accidental detonation of the explosives will be evaluated, data of previous failure events of similar equipment are reviewed and are used found to be approximately representative.
3.6.3 Consequence analysis
This part of study developed a computer simulation programming to analyze the consequence of explosion. QBASIC programming language is used to develop the program. TNT and probit model are the models that selected for consequences analysis.
For failure scenario of accidental detonation of the explosives, consequence analyses are carried out and hazard zones are computed. The areas are which fatalities would occur can then be quantified.
A. TNT model Baker 1973 introduced TNT model, where Mass Equivalent of TNT can be estimate using the following equation:
MTNT = mHc / ETNT . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . (1)
Where MTNT is the equivalent mass of TNT (mass) is the empirical explosion efficiency (unitless) m is the mass of hydrocarbon (mass)
Hc is the energy of explosion of the flammable gas (energy/mass), and ETNT is the energy of explosion of TNT.
Nowadays many researchers has been simplified the way to convert mass of explosive in Kg into Kg equivalent TNT, it is done by multiplying the mass of explosive in Kg with the conversion factor.
MTNT = (Mass of Explosive in Kg) x (Conversion Factor) ……………..……..(2)
The use of TNT as the ‘reference’ explosive in forming Z is universal. The first stage in quantifying blast waves from sources other than TNT is to convert the actual mass of the charge into a TNT equivalent mass. The simplest way of achieving this is to multiply the mass of explosive by a conversion factor based on its specific energy and that of TNT. Conversion factors for a number of explosives are shown in Table 3.1and 3.2 adapted from baker et al. From the table it can be seen that a 100 kg charge of RDX converts to 118.5 kg of TNT since the ratio of the specific energies is 53640/4520 (=1.185).
Table 3.1 Conversion factors for explosives Explosive
Mass specific energy Qx (kJ/kg) Compound B (60% RDX 40% TNT) 5190 RDX (Cyclonite) 5360 HMX 5680 Nitroglycerin (liquid) 6700 TNT 4520 Blasting Gelatin (91% nitroglycerin, 4520 7.9% nitrocellulose ,0.9% antacid, 0.2% water) 60% Nitroglycerin dynamite 2710 Black powder 572
TNT equivalent (Qx/ QTNT) – conversion factor 1.148 1.185 1.256 1.481 1.00 1.00
0.600 0.12
Conversion factor: Table 3. 2 Conversion factor for high explosives
Explosive TNT Nitromethane Pentolite ANFO
Approximate conversion factor by weight for Pressure 1 1.1 1.04 0.3-0.82
C-4 Ammonia Dynamite Gelatin dynamite Nitroglycerin Dynamite Tritonal H-6 Black powder Emulsion explosive PETN RDX
1.37 0.7-0.9 0.7-0.8 0.9 1.07 1.35 0.1 1.00 1.08 1.185
Experiments with explosives have demonstrated that overpressure can be estimated using an equivalent mass of TNT, MTNT , and distance from the ground-zero point of the explosion, denoted r. The empirically derived scaling law is,
Z = r / (MTNT)3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (3)
Where, Z, Scaling Value (m/Kg1/3), r distance (m), MTNT is mass equivalent to TNT (Kg),
Overpressure value can be estimated by using this following equation,
Ps = P / Pa . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . (4)
Where, Ps is the scaled overpressure (unitless) P is the peak side on overpressure, and Pa is the ambient pressure
P / Pa =
1616 [ 1 + (Z/4.5)2)] (1+ (Z/0.048)2)0.5 x (1+ (Z/0.032)2)0.5 (1+ (Z/1.35)2)0.5
. . . . . . . . . . . . (5)
P = Ps x 101.3 kPa . . . . . . . . . . . . . . . . . . . . . . . . . . . . (6)
For estimating the overpressure P at any distance r resulting from the explosion can be estimate by using the equation (1) until equation (6).
In recent days, the load noise is also considering in analysis the consequence. The sound pressure level can be estimate by following equation,
Lp = 20 log10 { [ P ] / [ 20 x 10 -6] } . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . (7)
B. Probit model
Probit model is very useful in order to determine the injury and damage due to the explosion. In this research, probit model used to determine the human injury. The types of injury for analysis consequence are deaths from lung haemorrhage and Eardrum ruptures. The probit variable Y computed from
Y = k1 + k2 lnV . . . . . . . . . . . . . . . . . (8)
Where, k1 and k2 probit parameters
Deaths from lung haemorrhage
Y= -77.1 + 6.91 ln V . . . . . . . . . . . . . . . . . . . (9)
Eardrum ruptures
Y= -15.6 + 1.93 ln V . . . . . . . . . . . . . . . . . . . (10)
Where V is overpressure value in unit N/m2 To convert the overpressure value P from (kPa) unit into overpressure value V in N/m2 unit, this following equation are needed,
V = P x [0.1451 Psi/kPa] x [101325 N/m2/atm] [1 atm/14.7psi] ………… (11)
After the probit value have determined its can be transform to the percentage value by using the following table.
Table 3.3 Transformation from percentages to Probits
3.6.4 Quantification of risk from all failure events
The present from the previous stage are summarized in integrated form. The results are presented in a contour plot representing the overall risk arising from accidents which could result in fatalities and ear drum rupture at the plant and its surrounding area.
3.6.5 Comparison of risk . The final stage of this assessment will deal with a comparison between the possible risk level arising from the option of this plant with commonly acceptable risk level.
CHAPTER 4 “Today, safety is equal in importance to production and has developed into a scientific discipline that include many highly technical and complex practices and theories.”
CHAPTER 4
4.0 THE DEVELOPMENT OF QUARRY INDUSTRIES IN MALAYSIA
Malaysia consist of two physical regions one known as Peninsular Malaysia which consist of nine state and other located on the island of Borneo consisting of two states. Peninsular Malaysia covers on area of 127 560 square kilometers and the Borneo states of Sabah and Sarawak covers on area 73 664 square kilometer and 102 528 square kilometer respectively (figure 4.1). The areas extends from 1O N to 7 O N latitudes and 99 O
E to 119O E longitudes, except for highland areas Malaysia has an equatorial climate.
4.1.0 Number of quarry in Malaysia
Malaysia blessed with abundances of mineral resources such as coals, rocks, tins, gold, sand, kaolin, ball clay, limestone and granite. These were encouraging the quarrying and mining industries in all over the countries. The industrial mineral sector is one of important sector for any society facing the challenges of industrialization. It provides much needed construction and building materials, road paving products among others for national development. Quarrying produces construction materials, which are vital for the development of the country.
Until the year 2004, Malaysia Quarries Association reported there were 322 quarries operating throughout the countries. The statistics shows in table 4.1 the number of quarries in every state in Malaysia.
Table 4.1 Number of quarry in Malaysia
State
Number of Quarry
Sabah
72
Perak
65
Pulau Pinang
16
Johor
33
Sarawak
33
Wilayah Persekutuan and
26
Selangor Negeri Sembilan
23
Kedah
12
Kelantan
11
Pahang
10
Terengganu
9
Melaka
6
Perlis
6
Total
322
Granite quarrying remains predominant with approximately 60 % follow by limestone 29%. Granite rocks form a large proportion of the Peninsular as outcrops and divided into three belts namely: the western belt, the eastern belt and the central belt. The
granite extracted is suitable for the production of aggregates and some have the quality of being for dimension stones market.
Rock Materials, for the construction industry, produced in Sarawak consists of stone, gravel and sand. Most of the crushed stones were used for local road construction and maintenance and as concrete aggregates in building construction. Various types of stones are also quarried in Sabah for the construction of roads and airfields. The most commonly used stone is the hard grey sandstone located at the Crocker Formation.
Limestone resources (including dolomite and marble) are plentiful with known reserves located mainly in Kelantan, Perak, Perils, Pahang, Kedah, Selangor and Sarawak. At present limestone is mainly consumed by the construction and building industries as aggregates, cement manufacture (60%), dimension stone, ornamental use; and also in the agricultural sector as soil conditioners, animal and plant food.
The quality of the Malaysian limestone varies from dolomite to limestone with high calcium content and low impurities. It is suitable for manufacturing of cement, quicklime. Hydrated lime, calcium carbonate powder filters, chicken food, fertilizers and other industrial uses. Marble can also developed into dimensions stones and as ornaments.
The quarry industry have benefited very significantly from many government funded project such as road works for rural developments, construction of new district
hospital, development of new teachers living quarters and upgrading and maintenance of multiple federal roadwork projects throughout the country. The demand of quarrying products has obviously increases from 33 million to 54 million metric tons in year 2001 (Peninsular Malaysia market only).
No
Year
Estimated Supply
Estimated
% Increase
(forecasted)
Volume
Sales
over previous year
Revenue
Sales
Sales
(RM‘000)
Volume
Revenue
1
2002
57,000
598,500
5.5
5.5
2
2001
54,000
567,000
2.85
5.35
3
2000
52,500
538,125
11
12
4
1999
47,250
472,500
43
51
5
1998
33,000
313,000
-
-
Table 4.2 Demand trend for last 5 years in Peninsular Malaysia (Volume:’000 M. Ton)
4.2.0 Quarry and environmental issues
Quarrying activities are associated with a number of environmental problems and issues, which include air pollution, water pollution, noise and vibration, fly rocks, and eyesore. Most of the time, the rehabilitation of quarry as receive very little attention from quarry operators.
The Department of Environment (DOE) is the government body, which is responsible to monitoring the quarrying operation in Malaysia from the beginning until the end of operation. Under Environmental Quality Act 1974, quarrying activities are listed as prescribed activities that are subjected to Environmental Impact Assessment.
According to the Department of Environment there are some conditions, which have not fully complied for environmental impact due to quarry operation with include:
1) Poor erosion and silt erosion management e.g sedimentation pond, silt traps and drainage systems were not prepared prior to earthworks;
2) Improper road constructions e.g main access road from the project site to the main road are not paved;
3) Poor dust control e.g control equipment for dust are still not efficient which includes conveyor systems being not full enclosed and slotted chutes from the conveyor to the ground level were not equipped;
4) Overburden management e.g dumping area located too near to the border of the land lease and that the material was not compacted and maintained at a suitable angle to prevent slope failures;
5) No monitoring and auditing programs e.g there are still a lot of project proponents which do not submit their respective monitoring programmes and reports to the Department of Environment
4.2.1 Air Quality
Blasting and crushing activities of quarrying operation generate a large amount of dust, which if not adequately controlled, would contaminate the surrounding areas. The degree and distance of contamination by dust depends on the prevailing wind direction, the strength of the charge used in blasting and the quantity of generated. The dust, which comprises fine particulates, will eventually disperse into the air.
World Health Organization (WHO) has set up the desirable air quality standard for dust is 250 mg/m2/day. Reading exceeding this standard signifies the degradation of the air quality in the neighborhood and people at the surrounding will be affected. The dust produced could settle on food, water and vegetation. It could also soil walls, furniture and clothing. It presents an economic costs as well as a nuisance and thus is a constant cause of complaint. The daily standard for dust or total suspended particulate (TSP) that has been recommended by DOE is 260µg/m3/day.
4.2.2 Water Quality Rivers are the most important sources of water supply in Malaysia. The DOE has been conducting river water quality monitoring since 1978. Suspended solid are the most
important parameter related to any quarry operation. The impact of a quarrying operation on water quality is thus “quite imminent” in view of its nature operation, which can cause direct physical disturbance of the environment surrounding the quarry site.
Department of Environment has set up the condition where any quarry operation on surface water regime, should not alter significantly the surface over which water flows, change the pattern and quantity of surface water flows through the cleaning and pitting activities and possibly soil, working face and overburden stoke piles.
In order to expose the rock for extraction, the removal of a certain amount of soil is required and the disposal of the stripped soil and overburden would be a major source of sediments learning the quarry area. A good management practice of overburden stockpiles can reduce the impact to the watercourse. The effect to the watercourse can be minimized measures such as seeding with suitable grasses or by planting of some leguminous cover crops after the area compacted.
4.2.3 Eyesore problem
Quarrying activities can unfortunately leave unsightly remnants and ugly scars permanently on the face of hills. This problem can occur during preparation of the land and quarry face for extraction of rock and if not well planned, not only will cause degradation to the air quality but also affected natural aesthetic beauty of the area concerned. These may lead to complaints from the community staying around the area
and may discourse local and foreign tourist from ever visiting the area due to unsightly view, and prevailing poor air quality because of the suspended dust content.
4.2.4 Encroachment
This is case where housing and infrastructure is allowed to exist near quarries without any regard for subsequent problems that may arise from quarry operation such a dust, noise, potential fly-rock, air blast and ground vibrations. Most of the quarries are scattered around the fringes town, but as the town expands, development have now encroached close to the boundaries at the existing quarries.
There are some examples in Malaysia where Quarry is developed near to the housing and infrastructure:
1) Rawang Quarry is bordered by KTM double tract railways line to the East Rawang River to the west; residential houses to the south and west, and TNB Power Transmission towers and new developed industrial areas to the north.
2) Kanthan Quarry is developed on Gunong Kanthan hilltops close to Ipoh – Kuala Kangsar trunk road and the North –South railway line hoses have been developed just to the North of the Hills.
3) The entire Langkawi Island have been will continue to be developed for tourism. The factory and quarry are located very close to the sea and various holiday resorts
4) Kimanis Quarry in Papar Sabah is very near to the School and main road towards Kota Kinabalu.
4.2.5 Schedule Waste Management
Schedule waste means any waste fall within the categories of waste listed in the First Schedule of Environmental Quality (Scheduled Waste) Regulations 1989. Extreme precautions are required in handling the waste to avoid any spillage or accidental discharge, which could pose a danger to the workers and surrounding environment.
In quarrying activities, schedule waste includes; engine oil, lubricants, spent oil and grease. If these materials are not properly managed, it could result in the contamination of the water and soil due to spillage and improper disposal during the maintenance of vehicle and machinery. Management of scheduled waste must follow the requirements stipulated under the respective regulations.
Fuel leakage from the tanks can also pose a potential environmental hazard and damage such as to the local water body and subsequently the water intake point. Fuel storage areas should have a bund to retain possible spillage amounting to 110% of the
tank capacities. This bund should be built to impermeable material such as concrete, clay, hydrocarbon resistant plastic sheeting or any other approved impervious lining material.
4.2.6 Storage Explosive (Magazine)
In recent days, the protection for storage explosive has given high attention due to threaten from terrorist and other factor that could cause an explosion in the storage explosive. Explosion due to the improper handling explosive in the storage might pose a big impact to the human and environment surrounding the storage explosive areas. The storage of explosive should be monitor under the supervision of Police Department and only competence person permitted in handling it.
CHAPTER 5 “If we are going to live so intimately with these chemicals – eating and drinking them, taking them into the very marrow of our bones – we had better know something about their nature and their power.”
CHAPTER 5
5.0 TYPES OF EXPLOSIVES FOR BLASTING OPERATION
Nowadays there are many types of explosives available to meet the varied requirements of the quarrying industries. Wide ranges of products are available, it is important to know about each type of explosive in order to select and use the explosive efficiently and safely.
Generally, explosives that used in quarry can be classified as bulk explosives and cartridges explosives. Bulk explosives, which include ANFO, slurry explosive and emulsion explosive. Cartridge explosive, which includes Nitroglycerin, based explosives such as dynamite and Ammonia dynamite.
5.1.0 Nitroglycerin based explosive
Nitroglycerin (NG) has been use for a long time as the most important sensitizer for commercial explosives. It is made by reacting a mixture of glycerin and glycol with a mixture of acids, during which the temperature must be carefully controlled. A wide range of NG based explosives are produced. They are packed in cylindrical cartridges, 25 mm diameter and larger, with lengths ranging from 200 mm to 1000 mm. Various paper shells or wrappers are used to package and protect it from moisture.
5.1.2 Straight Dynamite
Straight dynamite contains 15% to 60 % explosive oil (nitroglycerin plus ethylene glycol). In addition, antacid, carbonaceous material and sodium nitrate is used. A typical percentage formulation for 40% straight dynamite would be:
Nitroglycerin (NG)
40%
Sodium Nitrate (SN)
44%
Antacid
2%
Carbonaceous materials 14%
Tough they have high detonation velocities and good water resistance, they have high flammability, are highly sensitive to shock and friction and produce large noxious flame. As such straight dynamite have only limited use in ditching and under water blasting.
5.1.3 Gelatine Dynamites
Gelatine dynamite is similar to straight dynamite, except that the explosive oil has to be collided with nitro-cellulose to form a gel. The result is a cohesive mixture that has better than straight dynamite. The material is of higher density, rubbery and much less sensitive than straight dynamites.
5.1.4 Ammonia Dynamite
Ammonia Dynamites are actually ammonium nitrate explosive with NG. Generally, they supply the same blasting strength as most straight dynamites and are less costly. Typical constituents of 40% ammonia dynamite are:
Nitroglycerin (NG) 14% Ammonium Nitrate 36 % Sodium Nitrate Antacid
33 % 1%
Carbonaceous material 10%
They have high heaving effect, are hygroscopic and are desensitized by water and therefore, their application is generally to soft and where water conditions are not a problem.
5.1.5
Ammonia gelatin dynamites
Ammonia gelatine dynamites are similar to the corresponding ammonia dynamites except for the addition of nitro-cellulose to the explosive oil to form a gel. These semigelatinous explosives are equal in most respects to gelatine dynamites except for somewhat lower velocity of detonation and slightly less resistance to water, however,
their water resistance properties are greater than conventional ammonia dynamites. A typical formulation for 40% grade is:
Nitroglycerin (NG)
26.2 %
Nitro-cellulose (NC)
0.4%
Ammonium Nitrate
8.5%
Sodium Nitrate
49.6%
Carbonaceous fuel
8.9%
Antacid
0.8%
Fume characteristics are generally good in all strengths and for many uses an ammonia gelatine dynamite can replace a gelatine dynamite at a lower cost.
5.1.6 Semigelatine and nitrostarch explosives
Semigelatine dynamite is a hybrid formulation with properties between those of gelatine dynamite and granular dynamite (which contains no nitro-cellulose, has relatively low density and is susceptible to the effect of water). They combine the economy of ammonia dynamites with the water resistance and cohesiveness of ammonia gelatine explosive, contain less explosive oil, sodium nitrate and nitrocellulose, but more ammonium nitrate. They have low cost in comparison to comparable gelatine dynamite, offer good fume characteristics and water resistance and are suitable for underground use.
Nitrostarch explosive is a formulation in which the glycerin is replaced entirely by nitrostarch, eliminating certain objectionable characteristics such as NG headache and nausea. They contain no liquid sensitizers, cannot freeze and do not exude or leak during storage.
5.2.0 Ammonium Nitrate dry mixes (ANFO)
Prilled ammonium nitrate (AN) and fuel oil (FO) mixtures, known as ANFO, were introduced for blasting operation in mid 1950s. Since 1980s is widely be used for quarrying operation in Malaysia. Ammonium Nitrate in a proper form when mixed with carbonaceous or combustible material in appropriate proportion forms a blasting agents. Nowadays there are many form of AN could be used with a solid or liquid fuel to form a blasting agents. Through the years fuel oil has proved itself to be an almost ideal for AN. It is readily available, is inexpensive and easily mixed with AN to produce uniform mix commonly known as ANFO.
Small porous spherical prills absorb oil readily giving a dry mix which has good pouring properties. The microprills in each prill allow the AN to absorb and retain the optimum amount of fuel oil. The prill are hard enough to withstand transport shocks without breaking down, yet soft enough to breakedown and give a high loading density when blow loaded into blastholes with equipment such as pneumatic blasthole charger.
AN is stable at ambient temperatures but can absorb moisture from the atmosphere if the humidity is above about 60%. To minimize moisture absorption and caking, the prills are lightly coated with anti caking agents. While it is strong supporter pf combustion, AN is flammable, however it is an oxidizer.
Proper mixing of AN and FO is important for predictable explosive performance. Diesel is always been used as Fuel Oil to be mixed with prill ammonium nitrate. 3200 Velocity Of Detonation m/s
2800 2400 2000 1600 1200 1
2
3
4
5
6
7
8
9
10 %
Diesel Content in ANFO
Figure 5. 1 Influence of Diesel on VOD
The field mixture commonly employs consist of 94% AN and 6% FO, which ensures a slight oxygen deficiency fuel excess as a safety measure.
5.2.1 Mixing Method
The most common method of mixing small quantities of ANFO is to pour the correct amounts both ingredients into a hand operated mixer (concrete type) and after thorough mixing, tip the ANFO back into the empty blastholes. Any machine used for mixing should be designed so as to avoid the possibility of frictional heating and any bearings or greases must be protected from spillage of AN or ANFO.
5.2.2
Weakness of ANFO
Lack of water resistance is the major limitation and disadvantages of ANFO. AN is readily dissolved by water, and unfortunately the addition of ANFO. AN nitrate is readily dissolved by water. Both the strength and VOD of ANFO are reduced by the addition of water.
ANFO, which contains 10% water usually, fails to detonate. ANFO would be destroyed in a wet hole, such as is often the case in the Malaysian environment. Wet or waterlogged holes were always flushed using the air compressor before ANFO in a sausage package is being inserted first followed by the filling of prilled nitrate. A lot of time, what has happened is that sausage or th plastic protective lining will burst and the water seeps into the ANFO package. In situation like this ANFO is likely to be dissolved and misfiring occurs in blasthole.
In other scenarios, ANFO can be contaminated with water to produce burning or deflagration upon initiation leading to low order reaction and give off prominent brown fume. The blast will produce a lot of rock size of truck. In a better situation the rock could be just coarser due to decoupling effect of the explosive in the charged hole. Figure 5.2 illustrates the effect of water on ANFO in terms of VOD reduction.
4000
3000 Velocity Of Detonation m/s
2000
1000
0
2
4
6
8
10 %
Water content in ANFO Figure 5.2 Effect of water in ANFO performance
The efficient use of ANFO in wet blasthole depend almost entirely upon the protection given to it by polyethylene liners or by the packaging materials used to make up cartridges. Most ANFO product can be purchased in four forms. In increasing order of cost they are as follows:
1. Site mixing as bulk product obtained as separate ingredients 2. Pre mixed in bulk form on-site storage or direct borehole delivery 3. In paper, polyethylene or burlap packages 4. Rigid cartridges
5.3.0 Emulsion Explosive
Since the beginning of 1990, liquid bulk in form of water in oil Emulsion was introduced into Malaysia. The mechanical charging system immediately captured the attention of the quarrying sector. The most advantage of the bulk emulsion explosive system is its waterproofing properties, which provide superior rock fragmentation as compared to ANFO. Table 7.1 shows some of the important differences between the two systems. The bulk emulsion with its higher energy and velocity of detonation also fragments rock to a finer size, enabling better mucking and crushing. All these goodies allow the quarries to expand their drill and blast pattern to achieve tremendous cost saving.
Properties Drill pattern, 89 mm Fragmentation Density, g/cc VOD, m/s Water resistance Charging
ANFO 8’x 10’ Dry Acceptable wet Poor 0.85 3,000 Poor Manual
Bulk Emulsion 10’x12’ Very Good Very Good 1.2 5,000 Excellent Mechanical
Table 5.1 Comparison between ANFO and Bulk Emulsion properties
An emulsion is a two phase system in which an inner or dispersed phase is distributed in an outer or continuous phase. In simpler term an emulsion is a mixture of two liquids that do not dissolve in one another. This unique feature are coupled with the fact that minute size of the nitrate solution droplets are tightly compacted within the continuous fuel phase results in good intimacy between the oxidizer and fuel and increased reaction efficiency to other system.
The emulsion matrix obtained by emulsification of two immiscible liquids. By the process of emulsification two type of emulsion obtained, one is oil in water and other is water in oil. Water is in discrete dispersed phase in water in oil emulsion in the form of fine droplets dispersed in continuous phase which is oil phase. Whereas in oil –in water emulsion the reverse is true. Typical water in oil emulsion blasting agent has the following: Ingredient
Weight %
Wax/oil
6
Emulsifier
2
Water
17
Ammonium Nitrate
58
Sodium Nitrate
15
Glass Bubbles
2
Table 5.2 Ingredients water in oil emulsion explosives
A typical composition of oil in water emulsion explosive is as follows:
Ingredient
Weight %
Diesel(fuel oil)
6
Water
15
Sodium perchlorate
5
Calcium nitrate
20
Ammonium Nitrate
51
Glass Bubbles
2
Guar
1
Table 5.3 Ingredients oil in water emulsion explosives
The emulsion explosive have the oxygen donor consisting of nitrates and perchlorates in an aqueous solution. The water phase in this case sensitized by glass bubbles in the form of microspheres. Additional strength can be achieved by the addition of fuels such as aluminium powder.
Three products are available in emulsion category. These products are as given below: 1. Straight emulsion 2. Doped emulsion 3. Repumpables
5.3.1 Straight emulsion Basic formulation of an emulsion explosive can be presented as follows: Ingredient
Weight %
Ammonium Nitrate
60-70
Calcium nitrate/Sodium nitrate
0-20
Fuel oil
2-6
Aluminium
1-3
TNT and water
Varies
Table 5.4 Formulation of straight emulsion explosive
Straight emulsion are normally hot mixed at temperature over 50 C and a suitable chemical gassing agent is incorporated to control density. Since the final product is straight emulsion, the explosive displays exceptionally high water resistance, stability and explosive reaction efficiency leading to superior velocity of detonation (VOD) characteristics.
5.3.2 Doped emulsions
This is generic term for emulsion explosive to which varying percentage of ammonium nitrate are added to achieve a wide range of strengths. Pumpable characteristics as in the case of emulsion are maintained at all stages and so also the superior VOD and water resistance properties of emulsions.
5.3.3 Repumpable emulsions These formulations are designed for small and intermediate and apart from the normal advantages of emulsions are designed for pumpability at low temperatures. Product are available for wide range of strengths and diameters.
5.4.0 Slurry Explosives
Slurry explosive were first developed as a result of attempts to waterproof, improve density and strength of ammonium nitrate. A slurry is a mixture of nitrates such as ammonium nitrate and sodium nitrate, a fuel sensitizer, either explosive or non – explosive, and varying amounts of water. Although they contain large amounts of ammonium nitrate, slurries are made water resistant through the use of gums, waxes, and cross linking agents. Most commonly used fuel sensitizers are carbonaceous fuels, aluminium, and amnine nitrates. They are sensitized by are bubbles which are entrapped by churning the mixture. Even when none of the ingredients is in themselves explosive substances and it is only in the final stages of production that the compositions acquire explosive characteristics.
Slurry explosives are fuel sensitized ammonium nitrate (AN) with or without other oxidizer such as sodium nitrate (SN) or sodium perchlorate (SPC) or ammonium perchlorate (APC) in which the solid fuel and the solid part of the oxides are dispersed in continuous fluid medium generally an aqueous solution with or without other polar solvents and often more less aerated. They have been designated differently as slurry
explosives (SE) when they are sensitized with explosive (e.g TNT) and slurry blasting agent (SBA) when fuel is not an explosive (e.g aluminium, sulphur, and sodium hydrocarbon).
A Watergel is essentially the same as a slurry and the two terms are frequently used interchangeably. Slurry may be classified as either explosive or blasting agents. Those that are sensitive to a blasting cap are classified as explosive even though they are less sensitive than NG based explosives. It is important that slurries be stored in magazines appropriate to their classification.
Most non cap sensitive slurries depend on the entrapped air for their sensitivity and most cap sensitive varieties are also dependent, to a lesser degree, on this entrapped air. If this air is removed from slurry through pressurization from adjacent blast, prolonged periods of time in the borehole, or prolonged storage, the slurry may become desensitized.
5.4.1 Site mixed slurry/emulsion system
The Site Mixed Slurry (SMS) or Emulsion (SME) System of support of plant and pump trucks. The support plant is located near the site or at centrally located place if caters to a group of quarry. Non explosive ingredients are stored in it. Certain intermediates are prepared from some of these ingredients and kept ready. When the blastholes are to be loaded, the ingredients are loaded in specially designed pump trucks.
The pump trucks are specially designed to carry all the ingredients and to pump the blended slurry or emulsion into boreholes through a delivery hose carried on the truck. The blending operation is controlled by a sophisticated control system. The various ingredients are continuously metered and passed through a hose into the borehole. In case high energy bottom load and low energy top load is required, the desired quantity of each is set on the control systems
5.5.0 Explosive system
Most explosives are used in 2-, 3-, or 4-step trains that are shown schematically in Figure 5.3 a), b) and c). The simple removal of a tree stump might be done with a 2-step train made up of an electric blasting cap and a stick of dynamite. The detonation wave from the blasting cap would cause detonation of the dynamite. To make a large hole in the earth, an inexpensive explosive such as ANFO might be used. In this case, the detonation wave from the blasting cap is not powerful enough to cause detonation, so a booster must be used in a 3- or 4-step strain.
Figure 5.3 Explosive Systems a) two-steps explosives train, b) Three-steps explosives train and c) Four-steps explosives train
5.5.1 Priming Systems
Cap sensitive explosives are initiated by energy delivered from the initiator like a detonator. Whereas blasting agents such as ANFO products and many watergel and emulsion that are non-cap sensitive products do not reliably initiate with energy from a detonator. These products need additional energy from a primer or a booster. To achieve proper energy release from the explosive column adequate priming need to be incorporated in the explosive system.
5.5.2 Cast boosters
Cast boosters are explosive units designed to act as primers, comprising a mixture of PETN, TNT and other minor ingredients. Their high strength, high density and very high velocity and very high velocity (7000 m/s) make them suitable for priming ANFO mixtures and slurries. An additional advantage is their lower sensitivity to shock, friction and impact than gel ignites and other NG explosives. Cast boosters are manufactured in the range of 100, 200, and 250 g and above. Holes provided in the boosters permit in the insertion of electric detonators and the threading of boosters on to downlines of detonating cord.
5.6.0 Initiation systems
Initiation systems is defined as the system needed to start the detonation in the main charges it is include a great variety of specialty product, such as fuses detonators, and boosters charges. An initiation system consists of three basic parts: 1. An initial energy source 2. An energy distribution network that conveys energy into the individual blastholes 3. An in the hole component that uses energy from the distribution network to initiate a cap sensitive explosive
The initial energy source may be electrical, such as a generator or condenser discharge blasting machine or a power line used to energise an electric blasting cap, or a heat source such as a spark generator or a match. The energy conveyed to and into the individual blastholes may be electricity, a burning fuse, a high energy explosive detonation or a low energy dust or gas detonation.
Basically there are two methods of initiation, electrical and non electrical. Electrical initiation system utilize an electrical power source with associated circuit wiring to convey electrical energy the detonators. Non electrical detonators or as in the case of detonating cord, it is the hole initiator.
5.6.1 Electrical Initiation System
An electrical initiation utilizes an electrical power sources with an associated circuit to convey the impulse to the electric detonator, which in turn fires and initiates the explosive charge.
5.6.2 Detonators
All detonators (also called blasting caps) consist of a metal tube or shell 6.5 to 7.5 mm in diameter (outer) of varying length. Normally detonator shells are made of aluminum. At the closed end of the tube an explosive charge of either a single initiating explosive (mercury fulminate) or a combination of secondary explosive (base charge) and an initiating explosive charge (top charge) is placed.
The charges are compacted to give the desired strength and also ensure that they do not fall out while handling. It is necessary to ensure the detonators are capable of being stored over long periods under varying climatic conditions and they should function reliably and safely. Electrical detonators may again be classified as instantaneous and delay detonators.
A. Instantaneous Detonators
Instantaneous detonators fire within a few milliseconds after they receive current. The construction of these detonators has been described above. These are used when all the holes are to be fired simultaneously.
B. Delay detonators
For most blasting operation it is an advantage to have the various holes fired in a predetermined sequence with specific time intervals between detonators. The most notable advantages of delay detonators are:
1. Reduced vibration, airblast and flyrock 2. More predictable throw (amount and direction) 3. Reduced backbreak and overbreak, with working faces in an improved condition.
5.6.3 Non Electrical Initiation System
Electrical initiation system used were safety fuse and ordinary detonators and over the years it was considered that electric detonators were much safer, had better control on the timing of blast and were less hazxardous. In addition there are severe demands on the exploders. Several non electrical firing systems have become popular during recent years.
5.6.4 Detonating Cord
Detonating cord is a narrow core of finely powdered PETN enclosed in woven cover of polymer yarns and extruded plastics. Its water resistance and tensile strength can be varied through quality combination of the yarn and the plastic cover. Usually initiated by an electric detonator, its propagates a violent detonation with velocity of about 6500m/s a detonation sufficiently strong to initiate dynamite or the special primer explosives used
to initiate the insensitive blasting agent and to cause considerable
damage to ANFO through which it is led. The most commonly used High Energy detonating cord is one containing 40g/m explosive charge having a diameter of 7.0 mm. The breaking strength is excess of 100kg. HEDC is used to initiate insensitive explosive such as ANFO by side initiation.
5.6.5 NONEL System
Nonel is the common trade name of a series of blast initiation accessories developed by Nitro Nobel of Sweden, which uses shock tube principle. It is now manufactured and marketed by many countries includes Malaysia. Nonel is safe multipurpose firing system which combines the simplicity of fuse and igniter cord with the precision achieved with electric firing. The system is based on a plastic tube, the inside of which is coated with a reactive substance that maintains the propagation of a
shock wave at rate of approximately 2000m/s. This shockwave has sufficient energy to initiate the primary explosive or delay element in a detonator.
The Nonel tube is made of flexible plastic with an outside diameter of 3mm and inside diameter of 1.5 mm. In its standard form it is transparent and meets with most requirements in the blasting field. For specially tough condition a heavy duty (HD) tube quality is available, this has much greater resistance to wear, and has higher tensile strength. In its standards form Nonel tube is adequate for ambient temperatures of up to 50 C. The tube is crimped to a delay detonator. The Nonel detonator is made up as follow:
1. The visible part is an aluminum shell, the length of which may vary with the length of the delay.
2. Base charge a high explosive giving No.8 strength detonator
3. Primer charge a flame sensitive explosive.
4. The desired delay interval is provided by an aluminum tube delay element filled with a pyrotechnic composition, part of which is pressed directly into the shell.
5. The detonator is crimped against a rubber sealing plug which also protects a portion of the Nonel tube against wear
CHAPTER 6
6.0 APPLICATION AND HANDLING PROCEDURE OF MAGAZINE
6.1.0
Number of storage explosive in Malaysia
According to the Logistic Department under Royal Malaysian Police presently there are 295 registered quarries and 213 Storage Magazines in this country until the year 2002. The Police department is more concerned with the control and limit the excess of explosives for safety and security reason whilst other government agencies are responsible for the safe handling of these explosives at the work sites for the protection of workers, public and environment.
The Department of Occupational Safety and Health has their own requirement for blasting work at construction sites and also manufacturing the storage and use of explosives material at factories.
6.2.0 Explosive rules and regulation
The regulatory control over the manufacture, use, sale, storage, transport, import and export of explosive comes under the Minister of Home Affairs under the Explosive
Act 1957. The Act gives the police authority to carry out the actual regulating of matters pertaining to explosive controls.
The Explosive act 1957 (ACT 207) replaces all pervious enactment made in relation to explosives amongst which include the Explosive Enactment of the Federated Malay States (F.M.S Cap.200). However, by virtue of section 28(2) of the Act, all regulation made under the repealed laws continue to be force, applicable throughout Malaysia, and subjected to such modification as a necessary to bring the provision into conformity with the provisions said Act. In this connection, several modifications have been made to these regulations through the Arms and Explosives (Extension) order 1977.
Section 4 of the explosives Act 1957 empowers the Minister of Home affairs to prohibit the manufacture, possession or importation of explosives in the country. Section 25 empowers the minister, or any person authorized in writing by the Minister in that behalf, to authorize the construction of magazines (storage of explosives), or the establishment of such hulks, for storage of explosive. Section 25 states that it shall be lawful for minister, or any person authorized in writing by the minister in that behalf, to authorize the erection of such magazines or the establishment such hulks, as he may consider necessary, for the storage of explosives belonging to the Government of Malaysia or of any state, or for the storage or safe custody of explosives belonging to other persons.
Section 26 allows the minister to make regulation to regulate or prohibit the manufacture, possession, use, sale, storage, transport, import or export of explosive, the manner in which applications for licenses shall be made its condition, restrictions.
6.2.1 Explosive classification
Under the explosives Act 1957, “Explosives means gunpowder, nitroglycerin, dynamite, gun-cotton, blasting powders, fulminate of mercury or of other metal, colored fires, and every other substance used or manufactured for the purpose of producing a practical effect by explosion or a pyrotechnic effect and includes fog signal, fireworks, fuses rockets, percussion caps, detonator, cartridges, ammunition of all descriptions, and every adaptation or preparation of an explosive, any material for making any explosive and any apparatus, machine, implement or material used or intended to be used adapted for causing or aiding in causing any explosion in or with any explosive and any part of any such apparatus, machine or implement”.
6.2.2 Licenses
The licensing officer may on application being made to the developer and after satisfying developer that the premises are suitable and due precaution for the public safety has been taken, issues a license for storage and sales of explosive in any magazine, hulk, store house or shop. Licensing officer could be Chief Police Officer and includes any officer appointed by him in writing in behalf.
6.2.3 Inspection
Rule 20 stipulates that every person licensed to store explosive shall keep accurate records of all explosives stored. The record should be open to the inspection of the licensing officer and of any police officer not below the rank of Inspector.
6.2.4
Mining rules 1934
Under part VII of the Mining Rules 1934, Rule 61 lays out the procedure for the storage, removal and the safety measures to undertaken in relation to explosives. Additionally, Rule 61 (vii) requires the manager to appoint “shot fires”. Only appointed “shot firers” allowed to charge a hole with any explosive or to fire any charge, or to even carry any explosives into a mine. No person under the age 21 shall be allowed to the position of “shot firers”.
Based open rule 61 (vii), the Mines Department came to decision to issue “short firers” competency letters before 1957 and also certificates since the early 1990s to individual required for performing this specialized task in the mining sector. This competency for carrying blasting work at mines, quarries and at construction sites. For the benefit of the industry, the certificates are also issued to individual in quarrying industries. These practices are also carried out in the states of Perak, Kelantan and Sabah where the Department of Minerals and Geosciences (Mines department) is regulating authority over quarry operation under the States Quarry Rules.
6.3
Specification for construction storage explosive (Magazine)
Table 6.1 below shows the specification for construction storage explosive.
Table 6.1 Specification of construction storage explosive No
Specification
1.
It is must located in an isolated place and away from public, road, railways and other storage explosive fires residential areas.
2.
The site is well ventilated, dried and located in a relative cooler site
3.
Lighting arrester must be installed
4.
Security fence and barricade of a height up to the eaves of the magazine at distance of one meter from the magazine must be constructed.
5.
No iron or steel is exposed in the interior
6.
Interior dimensions are big enough to allow air to circulate freely about the stacked explosives
7.
The doors open outwards and are fitted so that it cannot be forced or easily removed
6.4
Handling procedure for storage explosive
Explosives for quarry operation are stored in the storage explosive should follow the right procedures in order to avoid from explosion and fire. Usually two compartment to store thee explosives is constructed in the storage explosive, there are :
1. Compartment to store main charge explosive , e.g dynamite, nitroglycerin, emulsion explosive)
2. Compartment to store detonators explosive.
Detonator should not be stored in the same compartment where the main charge explosives are stored. This is because the detonators are consists of the primer explosive that highly sensitive to friction, heat and friction. The safety precaution of storage detonators found more stringent then storage of explosive main charge.
6.5
Procedures in handling storage explosive
A competent person shall always be in charge of explosives in which explosives are stored, shall keep magazine keys, and shall be responsible that all proper safety precautions.
Table 6.2 Handling procedure for storage explosive
No 1
Handling Procedures for Storage Explosive Moisture damages all kinds of explosives, therefore every precaution should be taken to keep them perfectly dry.
2
Explosives of any kind, may not be exposed to sources of heat such as from radiators, steam pipes, stoves or any other sources of heat, such as direct rays of the sun. The heat tends to separate and decompose the explosives ingredients. Every effort shall be made to keep explosives cool and dry.
3
The door of a magazine shall be kept securely locked when people are not working in the magazine.
4
The ground around magazines shall be kept clear of leaves, grass, trash, stump or debris to a distance of 8 m prevent fire reaching them. Unsound trees in the vicinity which are tall enough to fall on a magazine shall be removed.
5
If a leak develops in magazine roof or walls, it shall be repaired at once.
6
The oldest stock shall always be used first
7
Open boxes of explosives may not be stored in magazines. Partially used boxes of explosives shall be resealed before returning them to magazine storage.
8
Magazine floors should be regularly swept and kept clean. Sweepings from dynamite magazine floors shall be destroyed by burning. Sweepings from black powder magazine floors shall be destroyed by throwing them in water.
9
In case magazine floors become stained with nitroglycerine, they should be scrubbed well with a stiff broom, hard brush or mop with a solution composed of one pound of sodium sulfide dissolved in 1-1/2 quarts of water to which 3-1/2 quarts of denatured alcohol and 1 quart of acetone. This should be stirred until a uniform mixture results and then stored in a polyethylene bottle. Plenty of liquid should be used so as to thoroughly decompose the nitroglycerine
10
Steel or metal tools may not be kept or used in a magazine, and any commodity, except explosives, may not be stored in a magazine.
11
Packages of explosives may not be opened, nor may explosives be packed or repacked in a magazine or within 15m of a magazine.
12
Explosives may not be left lying around where children or people may meddle with them. They shall always be kept under lock and key in a suitable magazine.
13
Magazine rules shall be posted in every magazine and these rules shall be complied with. The person or company who is the ultimate user, upon receiving delivery of explosives at a magazine shall, by means of a suitable stamp, mark each package, case and shipping container.
14
All access routes to an explosive substances store shall be kept clear of any obstructions and shall be fit for use.
15
Clearly legible safety signs and information boards such as the symbol representing explosive substances, signs prohibiting smoking and the use of open fire, and maximum allowed amounts of explosive substances to be stored in the facility shall be posted on the door of an explosive substances store.
6.6 Fire prevention step in storage explosive
Since fire and explosion is the major risk in almost storage explosive facility the precaution made to avoid the risk from occur. Fire prevention steps in Storage Explosive are as illustrated in the table 6.4.
6.4 Fire prevention steps for storage explosive No
Fire Prevention Steps
1
No smoking within 20m of the magazine, NO SMOKING / NO NAKED LIGHTS signs shall be prominently displayed around the magazine
2
Grass and undergrowth shall cut down and kept short in the area around the magazine
3
Flame or spark producing equipment shall not be used within 20 m of a magazine, where such equipment is required to carry out repairs to the magazine, all explosives shall be removed.
4
Paints, oils, petrol or any other flammable materials shall not be stored with detonators and main charge explosive, cleaning materials may be used in the magazine for maintenance but are to be removed when not in use.
5
A minimum of two extinguishers shall be in a prominent position outside each explosive store.
6
All fire fighting equipment is to be maintained in a fully serviceable condition.
7
Some form of lightning protection should be used.
8
listed articles that are not permitted into the magazine shall be prominently displayed at the entrance to the magazine. Details of the information to be shown on the board are as follows : Lanterns, oil lamps and stoves and all flame or fire producing
appliances. Matches, cigarette lighters or other portable means of producing a spark or flame.
Tobacco in any form and any article used for the purpose of smoking.
Inflammable liquids and solvents other than those authorized for maintenance work on containers or contained in the tank of a vehicle. food and drink. radio equipment (all types) including mobile phones. firearms with the exception of armed guards. drugs and medicines other than those forming part of an authorized first aid kit. Ammunition not authorized to be stored. Any unprotected power source.
CHAPTER 7
7.0 STORAGE EXPLOSIVE LOCATION AND DESIGN
7.1.0 Company background
Risk assessment study for storage explosive has been conducted in Kimanis Quarry Company Sdn. Bhd. It is located in Bukit Manggis, mile 3 old roads Kimanis, Papar Sabah. This company has been established since 1995, that producing sandstone for construction project around Papar district.
Company name : Kimanis Quarry (Sabah) Sdn Bhd Location
: 12 km from Papar Town
Size
: 9.5 hectare (23.48 acre)
Produce
: Sandstone
Since 1995, the nearest community made many complaints about the pollution effect from the quarry operation such as noise, vibration and fly dust. This situation was disturbed the community’s life mainly for the school community nearby the quarry site. The noise and vibration were come from blasting operation while fly dust come during transportation sandstone and stone crushing process.
7.2.0 Introduction of storage explosive (Magazine) in quarry site
Magazine of its existing quarry site to facilitate the blasting of rock activities. The purpose of the magazine is for the storage of explosives, detonator, fuses and material, which are considered dangerous and require special attention for its storage, handling and application.
In the operation of a quarry, substitution amount of explosives are required to be used. In the blasting operation as practiced by Kimanis Quarry Sdn Bhd, an approximate amount of 1000 kg of explosive used for each blasting. An average 5 blasting per month is carried out. This means that usage of explosive is 5000 kg/month.
The bulk of the explosive energy requirement is met by using ANFO, which is obtained by mixing ammonium nitrate and fuel oil. These ingredients are not explosives in nature and used to provide the bulk explosive energy when ignited as a result of a primary explosion using other readily ignitable explosives. The blasting operation is thus initiated using emulsion explosives and are detonated by detonating cord and delay fuses. Approximately 60 to 100 kg of emulsion explosives are required per month.
Apart form these explosives, detonators, fuses are also required. These detonators, fuses and emulsion explosives are purposed to be stored in bulk in magazine. The consequence of such accidents will have even greater impacts if the storage of explosive
(magazine) is located near to residential areas, as was the cases of bright sparkles company explosion in 1991.
7.3.0 Description of the magazine and its role in quarry
In view of the fact that transportation of explosive on public routes require extensive precautionary procedure it is not commercial and convenient to have the explosive transportation to the site as and when blasting is carried out. It is normal to erect a magazine close to quarry site and store sufficient explosive for a number of blasting. In this way, the number of times explosives are being transported will be minimized. Furthermore the blasting operation will be more flexible in terms of timing and frequency.
Apart from the quantity of explosive required the purpose of blasting work. A variety of explosive are also required to cater for different situation and bedrock condition. The most common is the combination use of Ammonium Nitrate (AN) and emulsion explosives. The main bulk of explosive energy will be supported by ANFO, whereas emulsion explosives will be used as a primary ignition explosive medium. Whereas emulsion explosives are presented as finished product readily for use, ANFO are blended product where the AN will be blended with FO as and when required.
Since AN and FO by themselves are not explosive in nature, their storage does not require in magazine and shall not for apart of the quantification of risk presented here.
Essentially, the focus will be on the emulsion explosives and the detonators, cord and fuses for the blasting. Most magazines are thus designed to store a specified quantity of emulsion explosive and not for the storage ANFO.
7.4.0 Site location
It is identified by map the quarry is located in lot no CL 025313642 Mile 3 Kimanis old road, Papar Sabah. Areas to the site via the main road from Papar to Kota Kinabalu, heading towards pass the forth junction 1500 m south of SMK Benoni. The quarry is located approximately 1.5 km from this junction.
7.5.0 Population and land use around quarry
The quarry sites near the hill area (Bt. Manggis) with an appropriate area of 10.72 acre. Adjacent and to the west of the site separated by a ridge, lies another quarry. Both quarries and their quarry are back to each other and form part Bt. Manggis.
To the north, of this quarry is hill area and behind of the hill is another quarry, which is Tan Keh Gup Quarry Sdn Bhd. To the eastern south is also hill area and the southern east is located another quarry, which is Kota Quarry Sdn Bhd. Extend to the west besides the roads is school area, which is Sekolah Menengah Kebangsaan Benoni Papar. Agriculture lots planted in the western northern which is planted with paddy, which is about 16 ha. Across the main access road (Mile 3 old road) is Kg. Benoni, comprising of small lots of
land used for both fruit tree planting as well as for residential purposes. Further to the south, residential areas found approximately 1 km from the quarry, with a small village called Kg. Langkawit. Figure 7.2 shows the location of investigated area and 7.3 shows the topography and land use of the surrounding area, Figure 7.4 contour map of Kimanis Quarry Sdn Bhd, Figure 7.5 shows the investigated area in 3-Dimensions and Figure 7.6 shows the quarry operation area.
7.6.0
Topography of the site and quarry layout
Figure 7.3 shows the topography of the quarry and its surrounding area, the hill being quarried is part of Bukit Manggis, which rises to approximately 50 m and 140 m above mean sea level (MSL). The crusher plant is located on the southern section of the site, on a largely level ground. The entrance to the quarry is by the western southern corner, of which an administrative and weight bridge and control room is located. The quarry face is on of the eastern northern of the site and facing west. The magazine or storage explosive is located on the eastern side of the site, approximately 30 m from the quarry face on the north and 130 m from the main access road. It is build at an elevation of approximately 20 m above MSL on an elevation ground.
7.7.0
Description of storage explosive (magazine) design
A good design of storage explosive could reduce the consequential effect of blast wave to the environment surrounding. The complete design of Storage Explosive shown in appendix section and the detailed specification design are explain below.
A – Separated Storage Compartment The magazine has two storage compartments. The main compartment is meant to store the strong emulsion explosive. Separated by an air gap of 3.5 ft between 2 walls of 4.5” thick. There is another annex compartment for the storage of detonators and fuses. This is in compliance with accepted normal procedures of storing the detonator and fuses with the main bulk explosives since detonated and faces were reported to be more readily detonated then the emulsion explosives. The building design of the 3.5ft air gap and 4.5” thick walls to ensure that in the event of accidental ignition of the detonators, the bulk emulsion explosives stored in the main magazine compartment will not be detonated in a chain explosion. B – Doors The entrances to the two compartments consist of 2 doors each. The outer door is joint with a piece of mild steel plate of 6 mm thick. The 1 ft air cavity between the two doors enables the cushioning of blasting of blasting effects in the event of accidental detonation of the explosions.
C – Sand Bag Bund A 1.8 ft high and 1200 wide sand bund is set up in semi rectangular styles surrounding the magazine. The wide sand bund is at approximately 10 ft away from the magazine wall. The bund begins on the western north section of the magazine, joining up with the high section of the hill and extents. Southern and end on the south, opening up to the main road entering the magazine in the site. On the eastern, side of the magazine the high ground of Bukit Manggis as a part of building requirement.
In the event of accidental detonation of the explosives stored within the magazine the nearest resident located to the western of the magazine are protected by the bund from fragmentation and flying sharpens arising form the blasting effects.
D-
Walls
Wall shall build up from brick with 2” cavity walls shell be at last 11” thick with proper of concrete composed of 1:3:6 mixes. An efficient damp proof course of asphalt copper or slots above the ground level and at floor level external and internal wall to be rendered with compo mortar (1:1:6)
E-
Ventilators
Galvanic iron ventilators fixed in external walls at the position shown on the drawings. Internal ventilators shall be copper gauge 60 mesh fixed on 2” x ½” timber frame and securely fixed to brick wall and stay good with external ventilators.
F-
Carpenter and iron mongery
Door frame shall be approved primary hardwood grade A. shelving wall be “Dark Meranti. All other timber shall be approved secondary hardwood grade B. All iron mongery to be brass throughout all allow 6 pairs 4” 2 3/5” bute hinges.
G-
R.C Flat Roof
R.C roof slab reinforced with M.S bars as shown on drawing.
H-
Foot Board
A moveable foot board shall be fitted as shown to slid in grooms and having a hand hole cut near top for lifting out.
I-
Sun roof
Constant sunroof, it consist of frame work of timber bolted together. The roof shall be supported on steel pipes. The roof covering with corrugated asbestos. The Sheeting security fixed to the purline with drives screw. The steel pipe columns shall be primes with good red paint and finished as specified for painting.
J-
Lightning Conductor
Lightning conductor is 2” diameter copper pipe for lower portion and 1 ½” diameter copper pipe for the upper portion with copper reducer and fixed with there prong. As terminal suitability fixed earth plate shall be of copper size 18” x 18” buried horizontally in drop ground not less then 6 feet from the wall of the magazine and surrounded.
K- Painting Internal and external woodwork of doors, shelving etc have 3 coats resin synthetic paint. External ironwork receive three coats of good quality (bludells) lexide metal paint of apron color.
CHAPTER 8
8.0 RISK ASSESSMENT STUDY FOR STORAGE EXPLOSIVE
8.1.0
Identification of hazards
The Magazine has been designed to store 2000 lbs of explosives. However, the management of Kimanis Quarry Sdn Bhd intents to stores the following quantity of explosion, which is sufficient for at least 6 months of quarry operation.
Table 8.1 Storage items and quantity of explosive in the Magazine Description
Emulsion Explosives
Quantity
Net Explosive
Capacity
TNT Conversion
Quantity
Storage
Factor
500 kg
500 kg
600 kg
1.000
12000 m
120 kg
220 kg
1.06
10000 m
50 kg
77.2 kg
0.12
10 000 pcs
4.5 kg
10 kg
1.185
(Emulite Gelatine) Cord 10 g (PETN) Safety Fuse (BLACK POWDER) Plain Detonator no. 8 (RDX)
The NEQ of the above is 674.5 kg or 1484 lbs, which is less than the designed storage capacity of the magazine. Further more, the magazine explosive are stored in two compartments. Separating the emulsion explosive from the rest of detonating material. It can be expected that the total effect of the risk should be much lower then from 1,484 lbs
of NEQ of explosives. However in line with standard practices of taking the most pessimistic view of a hazard in any risk assessment, a hazard arising from an explosion of 2000 lbs (907.2 kg) of explosives will be computed.
Identification of hazard for explosives and detonator done by study on the material safety data sheets (MSDS) and others sources from literature review. All the hazard data was extracted and summarized in the table below.
Table 8.2 Hazard identification of explosive Component
Emulsion Explosive
Detonator RDX
Physical State
Emulsion two phase Oil in water
Metals shells containing explosives with insulated metal leg wires
Flammability
difficult to initiate
Easy to initiate
Stable in nature
May detonate with impact or on heating
Stable in nature
Detonates with friction, impact, heat, low level electrical current, and electrostatic energy
Explosivity Stability/ reactivity
Cord
Safety Fuse
Hazardous breakdown product
Carbon dioxide, ammonia and nitrogen dioxide
Gases produced iron, lead, carbon and nitrogen oxides
Fire fighting
Evacuate and allow burn
Evacuate and allow burn
Inhalation
Irritation and allergic reaction Not a gas
Irritation and allergic reaction Not a gas
Ingestion
None
None
Acute Health Effects Skin contact
From the above one may conclude that the materials are non-toxic at normal conditions, but when involved in fire and explosion, toxic fumes of carbon monoxide, nitrogen oxides and ammonia may release. These have following exposure limits:
Table 8.3 Exposure limit for toxic fumes Material
Odor (ppm)
TLV (ppm)
STEL (ppm)
IDLHV (ppm)
CO
-
50
400
1500
N2O
-
50
150
250
NH3
50
25
35
1000
8.2.0
Quantification of failure frequency
In the quantification of failure frequency of a certain event, it is possible to follow a common approach of breaking down and tracing each action of failure into the simples and most basic form of failure, e.g. probability of lightning strike, electrical failure, human error of judgment etc. Based on historical record, a statistical number of failure rate can be attached contributing factor, and a total failure frequency can be generated by the application of fault tree analysis.
In the case of the Magazine, the assessment of failure is not complicated since it is not a complex plant, which has many scenarios of failure, for example, manufacturing processes line, transportation
movement, human handling, packing housing (during
manufacturing) etc. Failure analysis will depend largely on the experience and the
training of the operators. On the other hand failure due to other events like quantities based on past records. Precautions have already been taken to install lighting arrester for the magazine. Further more emulsion explosive is not readily detonable.
8.2.1 Historical Approach
A straightforward approach can be used by reviewing past records of accidents in the operation of magazines in Malaysia. It has been reported that there are slightly more than 213 magazines in operation in the last 37 years, there has not been any accidental explosion occurring from the magazine. In view of the above fact, it can be started that, the failure frequency is less than 1 in 7881/yr i.e 1.268 x 10 -4/yr.
8.2.2 Event Tree and Fault Tree Analysis
There 3 basics causes that will initiate the detonation of the magazine these are :-
1. Lightning strike induced detonation 2. Static discharge induced detonation 3. Hammer strike induced detonation
Figure 8.1 to figure 8.3 depict the events in the form of event trees. Table 8.4 summaries the probabilities of each action. Based on the event trees and the probability of events, fault tees for the accidents are shown in figure 8.4 to 8.6.
The total probabilities, taken from the above three events, suggest that it is 7.6 x 10
-5
/yr
this is in good agreement with the value as estimated from past records. i.e 1 x 10 -4/yr. This figure of 7.6 x 10 -5 probability of accidental explosion will be used to calculate the fatality rate arising from the operation of this magazine.
Lightning
Detonation
Yes
Explosion
Strike
Lightning Arrester
No Explosion
No Strike
No Explosion
Figure 8.1 : Event Tree of lightning strike induced detonation
Static Sensitive Clothing
Static Discharge
Ignition
Yes
Explosion
Yes
Yes
No
60/yr Handling
No
Yes
No Explosion
No Explosion
No Explosion
Figure 8.2: Event Tree of static discharge induced detonation
Hammer Drop
Sparking
Detonation
Yes
Explosion
Spark
Drop
No
Material Handling
No Spark
No Drop
No Explosion
No Explosion
No Explosion
Figure 8.3: Event Tree of hammer drop induced detonation
Table 8.4 Probability of events
Event
Probability per year
Justification
1.0 Lightning strike 1.1 Arrester Fault
10-1
Properly commissioned lightning arrester will outlast any building that it is supposed to protect.
1.2 lightning strike
10-1
Probability is very low that lightning will strike a building event without a lightning arrester. This value is used to represent a worst case scenario
1.3 detonation due to
10-3
lightning
This value is use in the Rijnmond Area report
2.0 Static Discharge 2.1 Handling
60/yr
This represent the number of times explosive is having handled in the magazine, i.e 5 blasting requirement per month, 60 handling per year
2.2 Wearing static
10-2
sensitive clothing
Unless clothing material is 100 % synthetic, which is very rare, and unfashionable, static sensitive clothing is not common.
2.3 Static discharge
10-2
Static build up is very rare in tropical climate due to high humidity. It is not known there ever happen a static build up in open air that is strong enough,
to be felt in this tropical weather. 2.4 Ignition Probability
10-3
This value is also quoted in the Rijnmond Ana report
3.0 Hammer Drop 3.1 Handling
60
This is the number of times explosive is being handled in the magazine
3.2 Hammer Drop
10-3
This represent an action which a handling and hard object is being dropped and a spark is created. Is required to handle the relatively small amount of explosive, this probability should be very low.
3.3 Spark
10-2
Not all cases of design will create spark. Unless the point of impact is very small and create a hot spot.
3.4 Near detonator
10-1
The place of drop may not be near a detonator to initiate detonation.
Explosion
10-5 /yr
AND
AND
Arrester Fault 10-1 /yr
10-2 /yr
Lightning Strike 10-1 /yr
Detonation due to lightning 10-3
Figure 8.4 : Fault Tree of lightning strike induced detonation
Explosion 6 x 10-6
AND
AND
60 x10-4 /yr
AND
Handling 60/yr
Wearing Static Clothing 10-2
Static Discharge10-2
Figure 8.5 : Fault Tree of static discharge induced detonation
Ignition Probability 10-3
Explosion 6 x 10-5
AND
AND
AND
Handling 60/yr
Hammer drop 10-3
Spark 10-2
Figure 8.6: Fault Tree of hammer drop induced detonator
Near Detonator 10-1
8.3.0 Computation of hazard scenario
The magazine has been designed to store up to 2000 lbs of explosives. This quantity of explosives poses a definite amount of risk of explosions. The following describes the explosions in the air in the event of being detonated.
8.3.1 Explosion in the air
In identification of hazards and failure scenario, the accidental detonation of the explosive can be traced to three sources.
1) Static discharge electricity discharge 2) Lightning strike 3) Accidental dropping of heavy objects
Explosion in the storage explosive will produce blast wave, load noise, fly debris and vibration. All these will effect to human and environment in surrounding area of the magazine.
The main factor, which govern the magnitude of the peak overpressure in a blast wave from the detonation in free air are :-
1) Distance of the wave from the center of the explosion D, 2) The weight of the charge W, 3) The explosion parameters of the charge
Overpressure (kPa) Vs Distance (m) 1200
1000
Overpressure (kPa)
800
600
400
200
0 0
50
100
150
200
250
300
350
Distance (m)
Figure 8.7 Graph : Overpressure Vs Distance (m) The graph in figure 8.7 shows that the overpressure as a function of distance calculated on the basis of the TNT model for the explosion in the storage containing emulsion
400
explosives, cord PETN, Safety fuse (Black Powder), and Plain Detonator no.8 (RDX) approximately 907.2 kg.
The overpressure at a given distance is proportional to the cube root of the weight of the charge for a given explosive. This cube root dependence can be derived from Hopkinson “principle of similarity” which states that the pressure and other properties of shock waves are similar if the scales of distances and time by which they are measured and change by the same factors as the dimensions so for the purpose of scaling the blast overpressure. Other parameter it is the shape of the charge is compact and symmetrical.
With the assumption, it is pessimistic to express the relationship between the weights of the explosive charge W, to the shockwaves effect at a distance D. A common empirical formula has been used widely to estimate the blast effect of the explosive as follow.
D = Z W0.33 ……………………………………………. (1) Where, Z is the scale factor D is the distance from the centre of explosion W is the weight of charge in TNT equivalent kg
Where weight of charge W in TNT equivalent kg could be calculated by the following equation :W = M x Co …………………………………………. (2) Where, M is the weight of explosive in Kg Co is conversion factor for a particular explosive
Since Z is the scale factor for the overpressure value P, the overpressure value can be estimated by using this formula :1616 [ 1 + (Z/4.5)2)]
Ps =
……………… (3)
(1+ (Z/0.048)2)0.5 x (1+ (Z/0.032)2)0.5 (1+ (Z/1.35)2)0.5 ………………… (4)
P = Ps x 101.3 kPa
Where, Ps is the scale overpressure P is the overpressure in kPa
8.3.2 Hazard computational The storage explosive designed to store 2000 lbs of explosives, this quantity of explosives poses a definite amount of risk explosion. The explosion overpressures depend on the peak overpressure that reaches the person. Direct exposure to high overpressure levels may be fatal. The fatality is a result of the explosion even though the overpressure that caused the structure collapse would not directly result in a fatality if the person were in a open area. In analyzing the consequence of blast wave the probit model was chosen. Two blast wave effects to human were estimated there are : -
1. Fatality 2. Eardrum rupture
The probit equation for these two effects are as follow : -
Effects
Probit equation
Human fatality
Y= -77.1 + 6.91 ln P ………………………….(5)
Ear drum rupture
Y= -15.6 + 1.93 ln P…………………………..(6)
Where P is the overpressure value in unit N/m2
The load noise is evaluated by use the following equation. Lp = 20 log10 { [ P ] / [ 20 x 10 -6] } . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . (7)
The equations (1) until equation (7) were used to develop the simulation programming by using QBASIC programming language. The outputs from computational hazard were analyzed in the following section and shown in table 8.6.
8.3.3 Human fatalities
The hazard zone for human fatalities is estimated from the center of explosion until 30 m distance approximately. For 100% fatalities to human being estimated within the distance 20 m from the center of explosion where the overpressure value is 235.7 kPa and the scaled distance Z = 2.55 m/kg1/3 . Fatalities expected to be 50 % at the distance 25 m and 1 % at the distance 29 m. The percentage of fatalities is gradually decreases by the distance. Table 8.7 present the probit results for human fatalities due to blast wave overpressure.
Table 8.7 Human fatalities due to Hazardous Explosion Overpressure Probit Value
Fatality rate
Peak Overpressure (kPa)
Hazard zone (m)
2.67
1
104.7
29 m
5.00
50
143.8
25 m
8.10
100
235.0
20 m
8.3.4 Eardrum rupture
The hazard zone for eardrum rupture is estimated from the center of explosion until 112 m. For 100 % eardrum rupture to human being it is found within the distance 20 m from the center of explosion where the overpressure value is 235.7 kPa and the scaled distance Z = 2.55 m/kg1/3 . Eardrum rupture to human being estimated to be 50 % at the distance 46 m, 30 % at the distance 55 m, 10% at the distance 72 m and 1% at 111 m. Table 8.8 present the probit results for eardrum rupture to human due to blast overpressure.
Table 8.8 Eardrum rupture due to Hazardous Explosion Overpressure Probit Value
Eardrum rupture
Peak Overpressure (kPa)
Hazard zone (m)
rate (percent) 2.67
1%
12.94
111 m
3.72
10 %
22.3
72 m
4.47
30 %
32.9
55 m
5.00
50 %
44.0
46 m
8.10
100 %
235.0
20 m
In fact the storage explosive itself does provide a first round every absorption of the shock waves. With proper design, the storage explosive will enable partial cushioning of the blast wave reducing the fatality probability. In addition, the construction of wide sand bag bund surrounding the storage explosive running from the western to the southern entrance provides important shielding.
The eastern section of the magazine are also surrounded by a natural barriers of the hill. High speed horizontal fragmentation due to the explosion will thus be effectively blocked by the wide sand bag bund as receptor. Vertical and near vertical projectiles does exist but their range will be limited. The explosion in the storage explosive will produce load noise that can effect to the human in the surrounding areas. Noise is measure in decibel unit and was estimated for this study and shown in table 8.8.
Table 8.8 Tabulate the noise level from the centre of explosion Distance (m) 100 500 1000 1500 2000
Noise level (dB) 117 102 96 92 90
CHAPTER 9
9.0 RISK QUANTIFICATION
9.1.0 Definition of risk
Risk to individual associated with an industrial activity can be divided into two categories which is voluntary risk and involuntary risk. Voluntary risk is measured as the risk to workers on the site, quantitatively this is defined as the expected annual fatality divided by the total number of events. It is expressed as,
Rv = FTV / Nv Rv = ETV / Nv
Where FTV is the expected fatalities per year and ETV expected eardrum rupture for a total number of Nv workers exposed to the hazards. On the other hands, involuntary individual risk is assessed as the expected total number of fatalities and eardrum rupture of human lives outside of the site divided by the total number of such persons exposed to the hazards involuntary, Thus as defined for RI .
RI = FIV / Nv RI = EIV / Nv
Where FIV is the expected fatalities per year and EIV eardrum rupture for a total number of people exposed to the hazards.
9.2.0 Fatality and eardrum rupture rate
In general, the expected total number of fatalities FT and eardrum rupture ET associated with operation and maintenance of the operation can be evaluate as summarization of the probability of each event times the expected of fatalities or eardrum rupture.
The fatality rate and eardrum rupture rate could be evaluate as,
FT = P(ei ) f (ei ) ET = P(ei ) e (ei )
Where,
P (ei ) = probability of occurrence of event, ei , and F (ei ) = expected number of fatalities due to event ei e (ei ) = expected number of fatalities due to event ei
The expected number of fatalities f(ei ) for a given hazardous event, ei can be compared as follows.
Where,
F(zj) = expected probability for a person located at as given hazard zone zj N(zj) = expected number of persons located at the hazard zone zj.
In quantification of risk due to the explosion in the magazine, there is only one source of hazard, the total number of fatalities is this.
FT = P(explosion all ) F(zj ) N(zj ) ET = P(explosion all ) E(zj ) N(zj )
To cooperate the expected number of persons located at the hazards zone z j, the population density and the surface area of the different sectors within the hazards zone zj is computed as follows :-
The expected fatality probability F(zj) and the expected eardrum rupture is in the range of the hazards zone z, for the failure and hazards scenarios have been quantified in previous section. The expected number of person N(zj) located at the particular hazard zone will be assessed in the next section. With the quantification of these probabilities and population densities, the risk to individuals inside and outside the plant can then be computed.
9.3.0 Population distribution
The largest hazard zone as drive at most 111 m from the centre of explosion. On checking the layout of the quarry and its surrounding area it shows that the areas of concern are mainly in the western to the northern section where the zone covers some residential and working areas where the workers are affected.
For persons exposed to the hazards, 46 workers located within the plant site are assumed to be within the hazard zone 111 m. In particular, all 20 workers are assumed to be within the hazards zone of 30 m. Only 2 workers is assumed to be within the 100% fatality probability of 20 m during the loading and unloading of explosives. It is also assumed that 4 other operators, including the driver, are located outside the bund within 25 m of the storage explosive. A fatality probability of 50 % is assumed. It is also reported 3 persons will stay overnight at the plant site. This will constitute the number of workers voluntarily exposed to the risk at night.
For persons exposed to the risk involuntarily, it is noted that the 113 m hazards zone extends to cover 2 houses to the western of the quarry. However, for quantification of fatality risk the persons in these house is not included it is only used for quantification risk of eardrum rupture. Table 9.1 and 9.2 Summarizes the distribution of population exposed to the hazards during day time and night time, both voluntary and involuntarily.
Table 9.1 Survey of population distribution exposed within the 30 m hazard zone for fatality Voluntary Risk
Involuntary risk
Plant site = 20 workers
No person are affected within the area
3 staying at plant site during night Total = 20 persons
Total = 0 person
Table 9.2 Survey of population distribution exposed within the 111 m Hazard zone for eardrum rupture Voluntary Risk
Involuntary risk
Plant site = 46 workers
House no. 1 = 5
3 staying at plant site
House no 2 = 6
during night Total = 46 persons
Total = 11 persons
9.4.0 Computational of fatality
Event though there are 3 cases to the explosion scenario, the final effect will eventually be the same. The previous section describes the population distribution of the hazard scenario, it is now possible to compute the total fatalities due to the accidental detonation of the explosives stored in the magazine.
For day time computation, it is assumed that the exposed populations are all present in Table 9.3 tabulates the breakdown of affected population with respect to the hazard zones, and the total involuntary and voluntary risk level. With 20 workers present within the hazard zone 30m, a total fatality rate of 1.15 x 10-4 / yr is calculated. With workers is thus calculated to be 5.75 x 10-6 /yr /person, which is much lower then the acceptable level 1 x 10-4/yr /person (ADB, 1990).
Table 9.3 Day time voluntarily and involuntary risk level (Probability of explosion 7.6 x 10-5/yr).
Range
Fatality rate
Voluntary Receptor
Involuntary Receptor
Number
Fatality
Number
Fatality rate
Exposed
rate /year
exposed
/year
0-20
100%
2
7.6 x 10-5
-
-
21 – 25 m
50 %
4
3.8 x 10-5
-
-
25 – 30 m
1%
14
7.6 x 10-7
-
-
> 30 m
0
0
0
-
-
20
1.15 x 10-4
0
0
Total
There is no involuntary fatality risk were found in this study because the hazard zone for fatality not exceed the residential area. For night time it is assumed that only 3 workers stay at the site to do security. However due to the fact that the causes of accidental detonation of explosive has been reduced to only that caused by lightning strike, the probability has dropped down from the daytime value of 7.6 x 10-5 /yr to 1 x
10-5 / yr. The single worker is assumed to stay at the front entrance of magazine (25 m within the wide sand big bund) and 2 persons stay in front entrance of quarry, where the distance is exceed 30 m. Correspondingly, the fatality rate can be calculated and is shown in table 9.4. The total night time voluntary risk level is calculated to be 5.0 x 10 -6 /yr/person and there is no involuntary risk found. The value is lower as compared to the acceptable level.
Table 9.4 Night –time voluntary and involuntary risk level (Probability of explosion 1 x 10-5) Range
Fatality
Voluntary Receptor
Involuntary Receptor
rate
Number
Fatality
Number
Fatality rate
Exposed
rate / year
exposed
/year
0-20
100%
0
0
-
-
21 – 25 m
50 %
1
5.0 x 10-6
-
-
25 – 35 m
1%
0
0
-
-
> 35 m
0
0
0
-
-
1
5.0 x 10-6
0
0
Total
9.5.0 Computational for eardrum rupture
For day time computation, it is assumed that the exposed populations are all present in Table 9.5 tabulates the breakdown of affected population with respect to the hazard zones, and the total involuntary and voluntary risk level. With 46 workers present
in the quarry, a total ear drum rupture rate of 1.45 x 10-4 / yr is calculated. With 46 workers voluntary risk is thus calculated to be 3.15 x 10-6 /yr /person.
Table 9.5 Day time voluntarily and involuntary risk level for ear drum rupture (Probability of explosion 7.6 x 10-5/yr).
Range
Fatality rate
Voluntary Receptor
Involuntary Receptor
Number
Probability
Number
Probability
Exposed
rate /year
exposed
rate /year
0 – 20 m
100 %
4
7.6 x 10-5
-
-
20 – 46 m
50 %
14
3.8 x 10-5
-
-
46 – 55 m
30 %
10
2.28 x 10-5
-
-
55 – 72 m
10 %
6
7.6 x 10-6
-
-
72 – 111 m
1%
4
7.6 x 10-7
11
7.6 x 10-7
46
1.45 x 10-4
11
7.6 x 10-7
Total
The total number of individual involuntary level is calculated to be event less. With 11 persons affected and a total ear drum rupture rate of 7.6 x 10-7 the individual involuntary risk level is calculated to be 6.9 x 10-8 /yr/person.
For night time it is assumed that only 3 workers stay at the site to do security. However due to the fact that the causes of accidental detonation of explosive has been reduced to only that caused by lightning strike, the probability has dropped down from the daytime value of 7.6 x 10-5 /yr to 1 x 10-5 / yr. The single worker is assumed to stay at
the front entrance of magazine (25 m within the wide sand big bund) and 2 persons stay in front entrance of quarry, 350 m from the magazine. Correspondingly, the rate can be calculated and is shown in table 9.6. The night time individual voluntary risk level is calculated to be 3.36 x 10-6 /yr/person.
Table 9.6 Night –time voluntary and involuntary risk level for ear drum rupture (Probability of explosion 1 x 10-5) Range
Fatality
Voluntary Receptor
Involuntary Receptor
Rate
Number
Probability
Number
Probability
Exposed
rate /year
exposed
rate /year
0 – 20 m
100 %
1
1.0 x 10-5
-
-
20 – 46 m
50 %
0
0
-
-
46 – 55 m
11 %
0
0
-
-
55 – 72 m
3%
0
0
-
-
72 – 111 m
1%
2
1.0 x 10-7
11
1.0 x 10-7
3
1.01 x 10-5
11
1.0 x 10-7
Total
The average individual involuntary risk level is 9.09 x 10-9 / yr / person, both of the risks are very low to be of any significant. Contour risk for fatality and eardrum rupture has been developed in the figure 9.1 and figure 9.2.
N
140
Tan Keh Gup Quarry Sdn Bhd
Old road to 2 Kinabalu Kota
80
Kota Quarry Sdn Bhd
50 20
7.6 x 10-5 3.8 x 10-5 7.6 x 10-7
Kg. Langkawit
Old road to Kimanis To Papar town
School Area S.M.K Benoni Paddy Field
Fruit Plant
new construction site
Kg. Benoni
0
Palm Plantation
1 cm
1 cm : 250 m Legend : 1 Labor line 1 2 Labor line 2 3 Labor line 3
4 Storage explosive 7 Office 5 Workshop 8 WC 6 Office 9 Canteen
10 Quarters 11 Processing 12 House no 1
13 House no 2
Figure 9.1 Contour risk for human fatality
N
140
Tan Keh Gup Quarry Sdn Bhd
Old road to 2 Kinabalu Kota
80
Kota Quarry Sdn Bhd
50 20
7.6 x 10-5 / yr
Kg. Langkawit
3.8 x 10-5 /yr
7.76 x 10—6 /yr
7.6 x 10-7/yr
Old road to Kimanis To Papar town Paddy Field
Fruit Plant
School Area S.M.K Benoni
new construction site
Kg. Benoni
0
Palm Plantation
1 cm
1 cm : 250 m Legend : 1 Labor line 1 2 Labor line 2 3 Labor line 3
4 Storage explosive 7 Office 5 Workshop 8 WC 6 Office 9 Canteen
10 Quarters 11 Processing 12 House no 1
13 House no 2
Figure 9.2 Contour risk for ear drum rupture
