| 1. |
- Bengtsson, Magnus, 1973, et al.
(författare)
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Cost And Performance Optimization Of A Tertiary Crushing Stage
- 2015
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Ingår i: ESCC 2015 Conference. - Göteborg : Chalmers University of Technology. - 9789188041012
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Konferensbidrag (refereegranskat)abstract
- There is increasing demand to optimise performance and profit of crushing plants. Research in this area has resulted in the development of numerous optimisation tools, and resent research has shown that the quality aspects of production have great influence on the optimisation results. The quality, cost, profit and capacity of a product is influenced by several parameters, and in order to control all of these parameters it is necessary to use some sort of optimisation software. In this paper, a novel approach use the parameters cost, profit, capacity and quality in order to perform a multi objective optimization of a crushing plant is presented. As an example a tertiary crushing stage consistent of a cone crusher and a vertical shaft impact crusher (VSI) is used as base for the designed objective function. The process has a given set of constraints that represents the conditions normal in these type of crushing applications. The first step in this paper is to identify if the range of the constraints can cause undesirable production costs when reaching for a given product property. The next step in the optimization shows how a strategy for relaxing constraint can increase overall productivity and still reach certain product properties. The conclusions made in this work are that multi objective optimization is essential when optimizing crushing plant production against multiple objectives. Relaxation of constraints can increase the overall performance of the crushing plant.
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| 2. |
- Johansson, Marcus, 1992, et al.
(författare)
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Investigation of High Speed Cone Crushing Using Laboratory Scale Experiments and DEM
- 2015
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Ingår i: Proceedings of the 14th European Symposium on Comminution and Classification (ESCC 2015). - 9789188041012 ; , s. 193-199
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Cone crushers are commonly used in secondary and tertiary crushing stages in comminution circuits. A multitudeof factors and variables influence the performance in terms of throughput capacity, size reduction, power draw and wear.Crushers are normally installed and operated at a fixed eccentric speed setting. By installing variable frequency drives and realtimeoptimization algorithms Hulthén and Evertsson have shown that the eccentric speed can be used as a variable to optimizethe yield and improve the performance. However, the influence of eccentric speeds above the normal operational range hasbeen scarcely reported on in the literature.This paper aims at reporting on the result from an exploratory study where experiments and simulations have been used toevaluate cone crusher operation at high eccentric speed levels ranging from 10-40 Hz. A laboratory Morgårdshammar conecrusher has been refurbished for the purpose of the study. A preliminary set of experiments have been performed where resultsshowed that the chamber geometry has a vital importance. The same behaviour as observed in the experiments was also furtherunderstood by using DEM simulations leading to the design of a new chamber geometry.The new chamber design have been evaluated using DEM at four eccentric speeds and two different close side settings. Therock model has been calibrated by single particle breakage experiments and is based on the bonded particle model. The productparticle size distribution has been estimated by image analysis of the bonded cluster discharge. The work addresses and showsresults relevant to three areas in comminution and engineering research; Simulation driven design, DEM modelling, Conecrusher theory.
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| 3. |
- Quist, Johannes, 1985, et al.
(författare)
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Poly-stream Comminution Circuits
- 2015
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Ingår i: Proceedings of the 14th European Symposium on Comminution and Classification (ESCC 2015). - 9789188041012 ; , s. 283-287
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Comminution and classification circuits consume significant amounts of energy. Some estimates show thatcomminution processes accounts for around 40 % of the total energy consumed in mining operations and 1.5-1.8 % of thetotal national energy consumption in mining intensive countries such as South Africa, Australia and Canada (Tromans, 2008).Apart from recent market fluctuations the global trend is that the demand for metals and minerals is increasing (Norgate andHaque, 2010). At the same time the ore competence generally increases as material is mined at greater depths and the grade isusually lower. The consequence is that increased amounts of raw material need to be processed in larger and largercomminution devices. The task of reducing the energy consumption in this context seems daunting.The conventional comminution circuit is usually based on a crushing and screening process followed by a tumbling millingprocess. HPGR machines and other new devices have also become more common during the last 20 years. Independent ofwhat type on units that are used in the circuits the global trend is that larger and larger comminution devices are manufacturedand installed.With this outlook as a foundation we propose an alternative mindset to think about circuits; poly-stream comminution circuits.A general trend in product development is that technologies transform from mono-systems to poly-systems. In this paper theconcept is described and exemplified in a case study including a comparison with a conventional SABC circuit. In poly-streamcircuits the material streams after one or several parallel primary crushing stages are split into 5-20 streams by using ore sortingand classification units. Each stream handles a proportional throughput capacity and the material passes through a dedicatedset of smaller comminution and classification modular units with settings optimized to target the specific properties of thematerial in each stream.The results of this conceptual case study suggests that smaller, instead of larger, comminution and classification units open upfor modularization, higher theoretical operational availability, better plant flexibility and expansion potential. Lower mass flowstreams enable the use of ore sorting with separate treatment and early rejection of gangue. It is generally also easier to achievehigher energy efficiency performance for smaller comminution, classification and separation units.There are a number of apparent challenges and problems associated with the concept. It requires new solutions for stream rerouting,sensor technology, advance control systems and advanced maintenance management systems to name a few. However,the consequent conclusion of this hypothetical concept is that perhaps the focus of research and development efforts shouldtarget material handling, sensor technology and comminution unit modularization in order to meet the challenges of futurecomminution circuits.
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