Paper No. 214
USING PROCESS INTEGRATION & OPTIMIZATION TO PROVIDE INTEGRATED PROCESS SOLUTIONS FOR MINING OPERATIONS, FROM MINE TO MILL E Isokangas1,*, W Valery2, A Jankovic3 and B Sönmez4 ABSTRACT The production of minerals for economic use is a two-stage process, involving mining to extract the mineral from the ground, and processing to convert the mineral into a marketable product. Generally, mining and processing have been viewed as self-contained entities. Both have separate objectives, separate cost centres and key performance indicators (KPIs) that do not reflect the customer/supplier relationships that inherently exist. However, mining and processing operations are inter-connected and therefore intimately inter-related with the performance of one operation affecting the performance of another. Optimizing each stage separately without considering the whole system often misses potential economic benefits and energy savings. During the past fifteen years, the authors have been involved in implementing a wholistic methodology “Mine to Mill Process Integration and Optimisation (Mine to Mill PIO)” to maximize the overall profitability of the operation rather than just optimizing any individual process in a mining operation. Metso Process Technology and Innovation (PTI), along with their project partners, have conducted several projects to significantly increase their production- generating typically 5% to 20% higher throughput and improve the overall mine and concentrator performance through PIO methodology. This proven methodology has applications ranging from greenfield projects to long-standing operations with AG/SAG, HPGR or conventional grinding circuits. This paper explains the Mine to Mill PIO methodology and discusses the benefits of such an approach on the energy consumption, the overall costs and benefits of mining operations. The paper also summarizes several case studies illustrating the use of PTI methodology in a variety of applications. Keywords: integration, optimization, simulation, modeling, mine-to-mill, comminution, blast, drill, crushing, grinding
INTRODUCTION PTI is a group providing Total PIO services for the mining and construction industries. The term “Total Process” is used to encapsulate the mining (drill and blast), comminution, flotation, leaching and dewatering processes and PTI studies aim to optimize each process within the constraints imposed by the operation of the other process.
1. Metso Process Technology & Innovation, Lokomonkatu 3, I-33101, Tampere Finland,
[email protected] 2. Metso Process Technology & Innovation, 1/8-10 Chapman Place Eagle Farm, Brisbane Queensland 4009 Australia,
[email protected] 3. Metso Process Technology & Innovation, 1/8-10 Chapman Place Eagle Farm, Brisbane Queensland 4009 Australia,
[email protected] 4. Metso Process Technology & Innovation, Anadolu Bulvarı Macun Mah. 179. Sok. No:4/AGimat Y. Mahalle-Ankara-Turkey,
[email protected]
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PIO methodology, developed by Metso (PTI), is a result of working with operations around the world over the past fifteen years to increase their production rates, reduce operating costs and improve overall process, energy and water efficiency. PIO projects are tailored to suit the requirements of the operation, but usually involve a site visit to collect historical data and information, collect current operational data, rock characterisation, complete mine and plant audits, surveys, detailed data analysis, mathematical modeling and simulations. Data collected from these site visits is processed and results are supplied in a report with conclusions and recommendations to the site. Often subsequent visits are then arranged to assist in the implementation of integrated operating and control strategies on site. Implementation of the PIO methodology has delivered significant improvements in mine efficiency, increases in the production of the operations with little or no capital expenditure and reduced operating costs at mines around the world. These increases typically range from 5 to 20 percent, representing millions of dollars in increased revenue (Dance et al, 2006). The benefits from increased throughput in the first year is usually more than ten times that of the cost of the study.
PIO METHODOLOGY Investigations by several researchers have shown that all the processes in the mine to mill value chain are interdependent and the results of the upstream mining processes (especially blast results such as fragmentation, muck pile shape and movement, damage) have a significant impact on the efficiency of downstream milling processes such as crushing and grinding (Kanchibotla and Valery, 2010). The “Mine-to-Mill Process Integration and Optimisation” approach involves identification of the bottlenecks and opportunities in the total process, understanding the leverage each process has on the downstream processes (e.g. the impact of drill and blast results on load and haul and crushing/ grinding processes) and then using that leverage to de-bottleneck the total process and maximize the overall profitability of the operation rather than just the individual process. In most metalliferous operations, the ore undergoes at least three stages of comminution: blasting, crushing and grinding. In the Process Integration and Optimisation (PIO) approach, breakage is moved back in the production chain where the energy requirements are lower and cheaper. Broadly, the approach entails increasing and/or better distributing the energy during blasting to produce Run of Mine (ROM) material that has a controlled top size and more fine material (particularly sub-grate size) (Kanchibotla and Valery, 2010). This may be coupled with reducing the primary crusher gap as the finer ROM enables this change to be made without compromising crusher throughput. The objective of Mine-to-Mill Process Integration and Optimisation methodology is to develop and implement sitespecific mining and milling strategies to minimize the overall cost per tonne treated and maximize company profit in a sustainable manner. The methodology involves a number of steps: benchmarking, rock characterization, measurements, modeling/simulation and where required, material tracking. A PIO project is normally comprised of a number of site visits spaced over a few months. Typically during the first site visit, project objectives are defined, data is collected to establish current operating practice and plans are made for conducting detailed audits, sampling for rock characterisation and plant surveys. This is followed by data analysis, modeling, and simulation studies to determine how to exploit hidden inefficiencies. Recommendations are followed by further site visits to implement changes, monitor results and ensure improvements are maintained over time. The PIO methodology is shown in Figure 1.
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Figure 1. Schematic of the PIO Process
Definition of Project Objectives Each project has different objectives, and therefore it is important to define the specific targets at the beginning of each project. Predominantly, the target is to maximize throughput, but there are also many cases requiring adjustment of product size, minimization of costs, or changes to the amount of fines. For example, in a SAG mill circuit, normally the object is to increase the amount of fines in the feed to increase production, but in a heap leaching process fines should be reduced to increase the percolation of the chemical solutions in the piles. Cost and production are normally opposed, i.e. if the goal of an operation is to increase production it will also increase its total costs, but the cost per ton will probably decrease.
Benchmarking and Process Audits A clear understanding of the current operating practices is necessary before a process can be optimized requiring an extensive data collection program. Blast design, implementation and initiation sequence are audited and blast fragmentation is measured. Blast design implementation is closely observed as an operation, which must be implemented accurately and repeatedly before expecting the gains from changes in blast design. TM
Material from the audited blast is tracked through the downstream processes using SmartTag . Surveys of the crushing and grinding circuits provide the necessary data to model each stage of comminution. Operating practices such as stockpiling and blending of different ore types ahead of the concentrator are also reviewed with consideration of the expected variability in rock properties. Finally, the level of instrumentation and process control strategies are reviewed to ensure that the mill operating conditions are best suited to changing rock conditions.
Ore Tracking from Mine to Mill (SmartTag™) In some cases, where material is blended before the concentrator or when sophisticated mine monitoring and dispatch systems are not in place, there is a need to monitor material movement from the mine to the concentrator. PTI routinely use passive Radio Frequency ID (RFID) tags to mark material and track its movement over time. Initially developed to assist in the PIO studies, PTI have commercialized this system under the name of ΤΜ SmartTag . The SmartTag™ system is an inexpensive and robust means of tracking parcels of ore from the blast, through ROM pads, crushers, intermediate stockpiles and finally into the concentrator. They are placed in the stemming of blast holes, on post blast muck piles or ROM pads and travel with the ore through the process until they are
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consumed, generally in the grinding mill. They are detected by antenna placed above or below conveyor belts at various points in the process; for example, at the primary crusher and SAG feed conveyor belts. The use of such technology allows definitive correlations to be made between plant performance and plant feed characteristics. These could be intrinsic properties of the ore such as grade, chemical composition, strength and structure, or due to the application of external energy such as blasting or crushing. In conjunction with online image analysis systems, the impact of fragmentation from different rock domains on downstream crushing and grinding can be determined. TM
Figure 2 demonstrates application of SmartTag ore tracking for a typical flow of ore from a blast through to a TM concentrator. Other possible applications for SmartTag ore tracking include tracking material through an iron ore concentrator or coal preparation plant (Wortley et al, 2011).
Figure 2. Schematic of RFID tag-based material tracking system TM
The SmartTag marker is based on an RFID tag encased in a shell to protect it from damage during blasting and TM its transit through crushers and stockpiles. The SmartTags come in three sizes, the super SmartTag (90mm Ø x 60mm), the standard (60mm Ø x 30mm) and the mini (20mm Ø x 10mm).
Ore Characterisation A detailed understanding of breakage characteristics of ore is very important for the successful implementation of Mine-to-Mill or Process Integration and Optimisation methodology. Breakage characteristics of ore for blasting will be different from that for crushing and grinding operations. For example, the rock mass structure and strength are important for blasting, whereas the micro fracture network, grain size, grain characteristics and breakage resistance may be important for crushing and grinding. Measurements of rock strength (Point Load Index, PLI and/or UCS), rock structure (Rock Quality Designation, RQD and/or fracture frequency) are used to define the blastability and breakage tests such as the Drop Weight and Bond Work Index tests are used to define the crushability and grind ability of the ore. Mineralogical properties are required to define the recovery and flotation characteristics. The techniques to determine the ore characteristics should be practical and the sampling should be statistically representative of the entire ore body.
Modelling and Simulation Rock characterisation measurements are used, along with data from site audits and surveys, to calibrate the blast fragmentation, crushing and grinding circuit models. Using these calibrated models, operating conditions such as
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throughput, power consumption and final grind size can be predicted based on estimates of future ore reserves and ore characterization measures, PLI (Is50) and RQD. Geotechnical drill core with measurements of Is 50 and RQD can be used to populate the geological block model with estimates of mill throughput using the PTI methodology. This forms the basis for the throughput-forecasting model. The blasting and comminution models calibrated to site operating conditions and ore characteristics are linked to model the complete blasting and comminution process. The models can simulate the performance of the process and predict key outcomes (like throughput and product size). Alternative operating strategies and conditions can be simulated and the outcomes compared to each other and the current situation to evaluate various strategies with minimal impact on the operation. Customized blast patterns can be developed to optimize both crushing and grinding performance. For each domain, blast designs are defined to generate the optimal fragmentation size for downstream processes. This may involve an increase or decrease in energy (powder factor in the blast), depending on the rock characteristics of each domain. The objective of any modified blast design is to minimize the overall cost for the entire process by distributing the energy required to fragment the rock mass, sensibly and effectively. Near-field vibration measurements and models are used to confirm that pit wall stability, damage and dilution issues are considered in the blast designs. In addition, the crushing and grinding models allow the impact of operational and control strategies to be investigated and optimized.
Implementation of Integrated Operating Strategies and Sustaining the Benefits Simulation results are used to determine the alternate designs and operating strategies for each process to improve the overall efficiency of the operation. Generally these alternate solutions require changes in more than one process and often the costs and benefits spread across different processes cost centres. In many cases, the costs are borne by one process cost centre (e.g. Drilling and blasting) whereas the benefits are realized in another cost centre (grinding). Risks involved in the implementation of these alternate solutions are discussed with all the key stake holders. Their buy-in to implement the solutions is vital to a successful implementation. Changes in management and the operation culture is required to implement the PIO in the long term. These include changes in the KPI’s for the operation in order to stimulate implementation of the PIO and appointment of a PIO team/coordinator responsible for monitoring and implementation of the PIO project. Upon agreement from the key stake holders, the alternate solutions are implemented in a controlled and staged manner. During this implementation, changes in design and operating strategies in each process and the resulting impact on the overall process are monitored carefully. Data from this implementation process is analyzed and any necessary modifications are made to the design and operational strategies. A cost benefit analysis will be conducted based on the data from the implementation program and the design changes will be incorporated in the standard operating procedures. Once the companies see the benefit, they tend to permanently apply PIO methodology. The mine and mill staff are trained so that they can implement the changes and sustain the benefits. One way of sustaining the benefits is through a continuous support contract with PTI, which includes training and technical support. The cost of the continuous support contract is case dependant but roughly similar to the PIO study.
APPLICATIONS OF PROCESS INTEGRATION & OPTIMISATION Two case studies will be summarized illustrating the PIO methodology in a variety of applications. All of these cases are actual projects conducted by Metso PTI in the past few years (Dance et al, 2009; Hart et al, 2011; Dance et al, 2011).
Case Study 1: SAG Mill Grinding Circuit This site operates a SAG mill, ball mill and pebble crusher circuit (SABC) that processes a range of primary ore of varying hardness from different pits which is blended with soft oxide material. PTI conducted a PIO study at a open pit gold mine operation to review drill & blast, crushing and grinding operations with the objective of increasing mill throughput while maintaining the current or possibly a finer grind
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size. In order to generate a finer feed size to the SAG mill several recommendations on improvements in practices for the drill & blast, crushing and grinding operations were made by PTI. The ore predominantly from two pits is currently processed in the plant. One is hard and coarse leading to lower SAG mill throughput, which has been characterized by site as being “SAG mill limited” while the other is characterized as “ball mill limited.” This ore is processed easier but results in - coarse product for the leach operation. The PTI study focused on ball mill limited material. Following the initial site observations, it appeared that two objectives should be focused on to increase the overall mill throughput while maintaining or achieving a finer grind size:
Changes in blasting practices to produce finer fragmentation from SAG mill limited ore to reduce SAG mill limitations and make it “appear” to the grinding circuit more like ball mill limited ore.
Modifications to the grinding circuit operation to better process ball mill limited ores with improved SAG and ball mill grinding and adjustments to cyclone operation.
Table 1 below compares ore hardness test results for the current and future pits. During the PIO study, the Pit-1 and Pit-2 were predominantly mill feed material. The JKMRC Drop Weight A*b values in Table 1 compared to Bond Work Index (BWi) values show that Pit-1 ores are typically SAG mill limited while Pit-2 ores are ball mill limited in the SABC circuit. Table 1. Ore Properties Drop Weight A*b
Bond Ball Work Index, kWh/t
Pit-1
22 to 28
15 to 17
SAG mill
Pit-2
Circuit Limitation
33 to 38
15 to 22
ball mill
**
26 to 57
11 to 21
variable
**
36
18
ball mill
Pit-3 Pit-4
Oxide *
*
Ore Source
***
76
BWi at closing screen size of 106μm,
10 **
Future pits,
***
A*b value derived from BWi by SMCC Pty Ltd.
During the benchmarking phase, PTI reviewed the current drill & blast systems and comminution processes. The quality of blast pattern implementation is assessed and the resulting ROM fragmentation measured using image analysis. To quantify the effect of changes in blasting conditions, material from the top and bottom flitches was fed separately into the grinding circuit as two separate trials in the PIO study. The benchmarking trial on Pit-2 top and bottom flitch material provided detailed data on blast fragmentation, primary crusher and grinding circuit performance that was used to developed models of the entire system. Image analysis of photos taken from the muck pile and trucks dumping at the primary crusher were used to calibrate a blast fragmentation model. Samples of the primary crusher product material were used to confirm the amount of fines being generate in the blast. Two full grinding circuit surveys conducted at the site as part of the initial benchmarking phase of the PIO project while processing the top and bottom flitches were used to calibrate a J K SimMet model. A simulation study was then completed to identify opportunities for higher mill throughput. A range of recommendations were made including changes in blasting (hole diameter and explosive type), primary crusher operation and grinding circuit operating conditions. Simulation results on similar Pit-2 material (combined with PTI experience) suggested that changes in blasting alone could increase mill tonnage by 4% while grinding circuit changes alone could increase tonnage by 6%. The combination of blasting and grinding circuit changes should improve throughput by even more than the sum of the two changes. Using the new conditions, the site prepared three blast patterns in the same area of Pit-2 as was tested in the benchmarking study earlier in 2009. These blast patterns were mined separately in top and bottom flitches, resulting in six mill trials that were carefully monitored by PTI. Samples were collected for sizing and hardness testing."
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Benefits from PIO Application The results of the validation trials showed a significant increase in mill throughput as a result of the finer fragmentation. Additional photographs of the muck pile and trucks dumping at the primary crusher confirmed an increase in fines content as well as greater similarity between the top and bottom flitch fragmentation. Primary crusher performance improved with higher throughput at the same power draw compared to the January 2009 benchmarking study. Table 2 summarizes the six validation trials compared to the benchmarking results for top and bottom flitch material separately. The expected increase in mill throughput predicted in the simulation study from the blasting and mill operating changes was clearly outdone by the validation trials. Table 2. Summary of Blasting Trial Results on SAG Mill Performance Feed properties Survey
Flitch
DWi kWh/m3
BWi kWh/t
Feedrate tph
% Oxide
SAG kWh/t
Grind P80 microns
Benchmark
Top
7.9
15.2
930
24.8
10.8
156
Trial 1
Top
8.3
20.8
1,167
21.9
8.4
177
Trial 2
Top
7.4
22.0
1,187
21.7
8.5
161
Trial 3
Top
7.3
18.7
1,132
13.8
8.2
148
Benchmark
Bottom
10.1
16.0
720
31.5
15.8
125
Trial 4
Bottom
7.5
18.1
1,117
12.3
8.7
214
Trial 5
Bottom
7.3
21.8
1,18
17.9
8.1
221
Trial 6
Bottom
8.5
18.0
1,149
11.9
9.0
221
The lower % oxide in the trials compared to benchmark feed was evident in the coarser final grind 80% passing (P80) sizes – particularly for the bottom flitch trials. In addition, samples of the trial feed showed a higher BWi value than was reported in the benchmark study. Further recommendations on ball mill circuit operating changes are being reviewed by the site (including the option of recycling cyclone underflow back to the SAG mill). Grind size improvement is an ongoing project being investigated by the site personnel since early 2010. As can be seen from Table 2, the six blasting trials showed an average SAG mill specific energy of 8.5 kWh/t for similar DWi values. This is compared to the benchmark Pit-2 result of 10.8 kWh/t and Pit-1 result of almost 16 kWh/t. The reduction in SAG mill specific energy by over 20% is a significant improvement in efficiency from the finer feed size generated by value-added blasting. Table 3 below summarizes the throughput increase at the site over the past few years since the start of the PIO project. Table 3. Throughput Improvements Over Time Condition
Period
Primary Ore tph
Oxide Ore tph
Total tph
% -106µm
Before PIO
Oct 08 - Jan 09
722
294
1,016
-
Benchmark Study
Jan-09
740
231
971
75.7
Validation Trials
Nov-09
963
192
1,155
76.6
Ongoing
Jan - Mar 10
938
163
1,101
76.3
30%
-45%
8%
-
% Change
Following recommendations by Metso PTI, site has maintained tighter settings on both the primary and pebble crushers to maximize the fineness of the product size. Other PTI recommendations included operation of the pebble crusher, SAG mill rock and ball load monitoring, ball mill media size and cyclone conditions.
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Implementation of PTI’s recommendations has resulted in increased plant stability and improved throughput. Completion of Metso PTI’s Mine-to-Mill PIO project at the site has resulted in sustained improvements in drill and blasting practices and process plant throughput.
Case Study 2: PIO for a HPGR grinding circuit This case study describes application of PIO for an open pit gold mine where the ore undergoes blasting, primary and secondary crushing, HPGR, ball milling prior the separation by flotation process. The aim of this study was to determine opportunities to increase throughput and improve overall circuit performance. Three trial blasts were audited by PTI at this site, and complete surveys were then conducted in the crushing and grinding circuits. TM
Three blasts were fired as part of the mine to mill campaign at the site. The data from the SmartTags placed on the blasts showed that the bulk of the material fed to the plant during the audits was from third blast; therefore, the focus of blast modeling and simulation was centred on that blast. A site specific blast fragmentation model was developed using the rock mass characterisation data and actual blast implementation parameters and the resultant ROM fragmentation as inputs to PTI’s Blast Fragmentation Model. In addition, a number of trucks were directed to a mobile screening plant where its contents were screened at 30 mm and 10 mm aperture to further calibrate the model. The model results show a very good match at both the coarse and fine ends of the particle size distribution. Using the calibrated fragmentation model, simulations of different blast designs were conducted to determine their affect on ROM fragmentation. The downstream comminution processes at the site will benefit from finer feed. Therefore, the main objective of the blast simulations was to reduce the size of the ROM fragmentation, both in terms of the fine (-10mm) and coarse size fractions. Blast simulations were carried out for different drill patterns. Simulations were also conducted for increased hole diameter. Table 4 provides details of the six simulations carried out as well as the audited base case. Table 4. Blast Simulations Parameter
Base Case
Option 1
Option 2
Option 3
Option 4
Option 5
Option 6
Hole Diameter, (mm)
216
216
216
216
254
254
254
Powder Factor, (kg/t)
0.44
0.55
0.65
0.73
0.55
0.65
0.73
Powder Factor, (kg/m³)
1.2
1.5
1.8
2
1.5
1.8
2
F80, mm
425
345
301
279
368
321
297
-10 mm, %
8
9.7
11.3
12.3
9.9
11.5
12.5
Fragmentation
Percentages of F80, -10 mm and cost changes relative to the base case were computed (refer Figure 3). It is shown that fragmentation becomes finer as powder factor is increased, with a reduction in F80 as well as an increase in the amount of fines (-10mm). Options with the larger diameter drill (254mm) offer cheaper costs at a given powder factor.
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Figure 3. Blast Simulation Results A number of changes to drill and blast were implemented at the site based on the recommendations provided by Metso PTI in October 2010. These changes included: a reduction in stemming length from 4.2 m to 3.5 m, different inter-hole and inter-row delay timings, different initiation sequences, and powder factors were applied according to the updated blasting cookbook. Further simulations evaluating the impact of stemming length, Velocity of Detonation (VoD) and drill pattern were performed. The results from these simulations suggest that fragmentation improves as the powder factor is increased, the stemming length is reduced and the explosive VoD is increased. A full comminution circuit survey was conducted while material from the audited blasts was being processed. The survey was divided into three stages: primary crushing, secondary crushing and HPGR circuit, and the grinding TM circuit. The SmartTag ore tracking system confirmed that ore feeding the plant during the surveys was from the mine to mill audited blasts. Historical operational data as well as information relating to ore properties and blasting parameters of the target ore were also collected. After mass balancing the survey data, models were developed and a simulation study was carried out. Survey mass balance results indicated good quality data sufficient for calibrating site-specific J K SimMet models of the crushers, HPGRs, ball mills and cyclones. After having completed the model calibration of each crushing and grinding stage at the plant, they were combined to obtain the model of full comminution process.
Process Simulations The main objective of process simulations was to identify strategies for increasing plant throughput; and improve crushing and grinding equipment utilization. A number of opportunities to increase the amount of fine material in the ROM through changes in blasting practices were identified in the drill and blast investigation. The simulations were first carried out to show the effect of finer ROM size distribution on the performance of the crushing and grinding circuits operating at the same throughput and conditions as the base case. A finer ROM size distribution resulted in a finer primary crusher product and reduced the primary crusher power by more than 20% in comparison to the base case. However, the results also indicated that the effect of a finer ROM on the secondary crushing circuit would not be pronounced unless the primary and secondary crushers are fully utilized. Therefore, simulations were performed with a tighter primary crusher closed side setting (CSS) while maintaining the same power draw as the base case. The primary crusher with a tighter CSS generated a much finer product in terms of 80% passing size. With this
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finer feed, the secondary crushing circuit was able to treat 20% more material at the same power draw as the base case without increasing product size. Following the findings from the simulation of blast options, additional simulations were conducted to investigate the effects of different operating conditions in secondary crushing, HPGR and ball mill circuits on the overall circuit performance.
Benefits from PIO Application The PIO Methodology looks at all aspects of the operation, and considers each in the context of the whole operation; thus achieving the best overall result. Implementation of PIO at this site has contributed to improvements in all areas from rock characterisation, through drill and blast, to crushing and grinding. Together with improvements in operational, maintenance and process control practices, PIO initiative has contributed to a steady improvement in operation performance over time. For example, the improvement of secondary crusher capacity and utilization over time is shown in Figure 4.
Figure 4. Improvement in Secondary Crusher Capacity and Utilization Simulation results have assisted in making changes and improvements in the crushing and grinding circuit and the effect of these changes is well understood by the operational staff. The comminution circuit models have been updated over time to reflect the changes and provide a useful tool for evaluating future alternatives with minimal impact on production.
CONCLUSIONS The concept of Mine-to-Mill has been applied in the mining industry now for over a decade. Metso PTI have been involved with many of these projects and developed a proven methodology called Process Integration and Optimisation. The methodology involves benchmarking, rock characterisation, measurements, modeling/simulation and where required, material tracking. The rock characterisation step defines blasting domains and allows different blasting and crushing strategies to be developed. Based on the domain definitions, blasting, crushing, and grinding models are used to determine specific operating and control strategies that optimize the efficiency of processing each domain. This methodology has been used in a wide range of applications from conventional circuit optimization, throughput forecasting and greenfield
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operations. For existing operations, significant increases in performance have been realized through the application of this methodology. Modelling and simulation of blasting and comminution has reached the point where it can be constructively used to explore the interactions between mine and mill and to indicate changes which have the potential to improve company profitability. Case histories such as that illustrated in this and other papers plus growing experience in the field show that it is possible to improve the overall economic performance of mines.
REFERENCES Dance, A, Valery Jnr, W, Jankovic, A, La Rosa, D, Esen, S, 2006. Higher Productivity Through Cooperative Effort: A Method Of Revealing And Correcting Hidden Operating Inefficiencies, in Proceedings of an International Conference on Autogenous and Semiautogenous Grinding Technology [CD-ROM], pp 375–390 (Vancouver, Canada). Dance, A, Kanchibotla, S, Mwansa, S, Dikmen, S. and Valery, W, 2009. Process Integration and Optimisation – Final Report, Submitted by Metso Minerals Process Technology & Innovation. Dance, A, Mwansa, S, Valery, W, Amonoo, G and Bisiaux, B, 2011. Improvements in SAG mill throughput from finer feed size at the Newmont Ahafo operation, in Proceedings of an International Conference on Autogenous Grinding, Semiautogenous Grinding and High Pressure Grinding Roll Technology [CD-ROM], p# 011, (Vancouver, Canada). Hart, S, Rees, T, Tavani, S, Valery, W and Jankovic, A, 2011. Process integration and optimisation of the Boddington HPGR circuit, in Proceedings of an International Conference on Autogenous Grinding, Semiautogenous Grinding and High Pressure Grinding Roll Technology [CD-ROM], p# 126, (Vancouver, Canada). Kanchibotla, S, S, Valery, W, 2010, Mine To Mill Process Integration And Optimisation – Benefits And Challenges, International Society of Explosives Engineers 2010 G Volume 1. Wortley, M, Nozawa, E, Riihioja, K, 2011, Metso SmartTag – The Next Generation and Beyond, in Proceedings of th 35 APCOM Symposium, pp 841-851, (Wollongong, NSW).
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