Simplified Life Cycle Assessment of a Belt Conveyor

©FME Belgrade, 2015. All rights reserved.

Proceedings of the XXI International Conference MHCL’15

Miloš D. Research Assistant University of Belgrade Faculty of Mechanical Engineering

. Professor University of Belgrade Faculty of Mechanical Engineering

P. Assistant Professor University of Ljubljana Faculty of Mechanical Engineering

This paper presents simplified life cycle assessment (LCA) of a bucket wheel excavator (BWE) belt conveyor. Conducted analysis should provide insight in most of the issues concerning sustainability and environmental properties of the belt conveyor. This paper also provides recommendations for improvement of the belt conveyor based on previous studies and sumarized results based on analysis of complete conveyor presented here. It should also serve as a starting point for complete LCA of the belt conveyor. The aim of complete LCA is to provide more detailed review of environmental properties of the belt conveyor and possible improvements of its energy efficiency, energy and cost savings. All of these analysis should serve as a basis for establishing methodology for LCA studies of any BWE or similar types of belt conveyors. Keywords: belt conveyor, eco-design, life cycle assessment, ecodesign assistant, ecodesign PILOT.

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Purpose of this paper is to present simplified life cycle assessment (LCA) of a bucket wheel excavator (BWE) SchRs 1201 belt conveyor and create starting point for complete LCA of the same belt conveyor. This analysis leans on previous work published in several papers. At first concept of sustainability and related terms such as energy efficiency and energy saving are explained in [1]. Folowing papers present simplified LCAs of the main belt conveyor components such as: the idler [2], the drive pulley [3], the belting [4], and the electric motor (EM) [5]. All of these simplified LCAs were conducted with Ecodesign Assistant (EA) and Ecodesign PILOT (EP) software tools [6], [7]. 2. #%!&" "'(%&!"#$

The belt conveyor components can be divided into five main groups: 1. Idlers/rollers, 2. Pulleys, 3. Belting, 4. Electric motor (EM), 5. Other Estimated minimum belt conveyor life time was 5 years. Determined functional unit was: "Transportation of 3465 m3/h of brown coal". 2.1 )

There are three types of idlers used in this conveyor: impact idlers, carrying idlers and return idlers. Carrying and impact idlers are troughed and they are consisted of Correspondence to: Milo , Research Assistant Faculty of Mechanical Engineering, Kraljice Marije 16, 11120 Belgrade 35, Serbia E-mail: [email protected]

three rollers Ø159x600 mm. Exceptions are two idlers adjacent to the terminal pulleys - transition type idlers. They are consisted of only one roller - center roller. Impact idlers are equipped with rubber discs and rings. Return idler is consisted of one horizontal roller Ø159x1800 equipped with rubber discs and rings. Certain assumptions were made in order to simplify the analysis: x it is assumed that all rollers are Ø159x600 mm smooth rollers, x return idler rollers are presented with three flat rollers equipped with rubber discs and rings, x impact idler rollers are presented with three troughing rollers equipped with rubber discs and rings, x all idler ball bearings are presumed to be 6310 C3 type, x ball bearings are treated as parts predominantly made of steel. Recently conducted simplified LCA with EA and EP justified this assumption. This analysis also showed that most significant stage of bearing life cycle is its production stage since there are many production processes involved. Bearings lubrication had no influence on this analysis. It will be discussed later. In accordance with these simplifications all idlers are presented with 47 smooth rollers Ø159x600 mm, 392 rubber discs, 196 rubber rings and 94 ball bearings. 2.2 Pu

This particular belt conveyor consists of two pulleys: drive pulley and return/take-up pulley. Both of the pulleys are made of the same or similar parts. The main difference between these two pulleys is difference in their weight. Drive pulley is approximately two times heavier than the take-up pulley. Therefore both of the pulleys are presented with drive pulley 1,5 times heavier than the original one, see Table 1.

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This particular belting is 3-layer flat composite consisted of three reinforcing plies and rubber covers and interlayers. Reinforcing plies are made of polyester and polyadmide.

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The EM is 132 KW, IE2 (high efficiency class), low voltage TEFC cage motor type ZKE 315 Mb-4 [5]. 2.5 "+

Other components comprise: 1. Drive (without EM), 2. Take-up device, 3. Accessories. The drive is consisted of EM, gearbox unit, coupling, and drum brake. The EM is the only component that consumes electric energy. Because of that it had been analysed separately in paper [5]. In accordance with [8] there are two basic types of take-up systems used on belt conveyors: manual and automatic take-up systems. Common types of manual (or fixed) take-up systems include screw, hydraulic, ratchet and jack-operated take-up devices. There are also hybrid types of take-up systems that are often of a telescopic tube design, which employ compression springs or hydraulic or pneumatic systems. Automatic take-up systems can either act passively as with gravity or actively with controlled power provided by hydraulic, electric or pneumatic means. The most common type is the gravity take-up system. Automatic take-up systems can also be of hybrid type, powered by spring compression, hydraulic telescopic tubes or pneumatic pressure [8]. From the eco-design point of view, there are two basic types of take-up devices: 1. take-up devices that do not consume energy, and 2. take-up devices that consume energy. The first category of take-up devices can be treated as parts predominantly made of steel (or some other material) and manufactured by machining with generation of 10% waste in production process regarding to parts weight. For the second category, the type and amount of consumed energy per use should be considered. Consumed energy should be added to the total energy consumed by the belt conveyor in use stage. Plows, cleaners and all other components that are not already been analysed are listed among the accessories. From the aspect of eco-design, these components can be devided into two groups also: 1. one that does not need any form of energy, and 2. the other - powered by some means of energy. They can be analysed in the way previously shown on the take-up device as an example.

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In accordance with previously conducted simplified analyses presented in [2], [3], [4] and [5], the belt conveyor is divided into several groups of parts, as shown in Figure 1. Some parts of the belt conveyor have been neglected in accordance with "cut-off" criteria. Parts with less than 5% share in production energy or weight of the whole component are not taken into consideration for analysis. Exceptions are hazardous substances, such as lubricants, which have to be taken into account regardless to their production energy or weight share. There are two options for consideration lubricating grease and gearbox oil during analysis: 1. as product part in raw material stage, and 2. as auxiliary material in use stage. Both options give the same result.

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Idlers/rollers are analysed as shown in paper [2]. All rollers are presented with 47 smooth rollers made of steel, out of which 31 are impact and return rollers, which are equipped with rubber discs and rings. Therefore all components of idlers can be presented with two groups of parts: steel parts and rubber parts. Pulleys are analysed as shown in paper [3]. They are presented with steel parts, alloyed steel parts and rubber parts. The conveyor belt (belting) is presented with carcass and covers as in paper [4]. In accordance with paper [5] the electric motor (EM) is presented with folowing groups of parts: windings and bars, housing, stator and rotor steel parts. Data for the belt conveyor drive components and chute required for the analysis are listed in Table 1 and summarised in Figure 1. Take-up device is of manual screw type and it was not considered in this analysis. It could be included in the analysis as already described in Chapter 2.5. All other common components of the belt conveyor that are not included here will be discussed later.



Parts of packaging for all components were summarized and presented with euro pallets and wooden cases. Different parts of the belt conveyor are packed into the appropriate wooden cases. Wood density of 500 kg/m3 and thickness of 30 mm were used for the purpose of the calculation. There were used 12 euro pallets of 24 kg and 380 kg of wood for cases. 3.2 : 6 6* *

Total energy input for all components of the belt conveyor was calculated in accordance with papers [2], [3], [4], [5] and recent research on the same subject, see Figure 2.

by "Kolubara Univerzal" production facility. Required energy for manufacturing rubber covers of 800 kWh included energy consumed by mixing, homogenisation, calendering, confectioning and vulcanizing processes. Mixing mill consumes large amount of lubricating oil. Production of basic rubber mixture for this belting required 0.8333 l of List 2 lubricating oil as process material. Energy required for manufacturing carcass is calculated as IM of 112.64 kg of plastics (EP & PA), and it equals E IM = 2140 MJ. Calculated energy required for production of the EM was 1323 MJ, as presented in [5]. Manufacturing of gearbox required 2230 MJ of thermal energy, see Table 3. Casing was made of cast iron (class IV), output shaft flange of high alloyed steel (class VI) and the rest of gearbox parts were made of steel (class III). For proper operation gearbox needs to be lubricated with oil. It consumes 50 l of Reduktol oil per year. 93. # 6 *6 6 * 9