| 1. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
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Modelling of Discrete Downtime in Continuous Crushing Operation
- 2015
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Ingår i: Computational Modelling 2015, MEI conference.
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Konferensbidrag (refereegranskat)abstract
- Crushing is a harsh process and production units are subjected to wear and failure over time which will reduce the overall performance of the plant. To achieve optimum process performance, both time dependant process dynamics and operating conditions should be taken into account.In this paper the aim is to create a framework for simulating the process from a more operational perspective to evaluate process performance and process optimum for different operational scenarios. The objective is to model and simulate the discrete phenomena that can cause the process to alter performance and implement it with dynamic process simulations. A method for combining discrete probability simulations with time-continuous simulations for process evaluation and optimization is presented. The proposed framework demonstrates a systematic approach to evaluate the process performance and locating optimum process configuration, for a given condition. The developed models can be used to optimize different aspects of the operation depending on the defined objective function and the system boundaries. Optimization of process throughput by manipulating configuration of both the grizzly and the crushers, as well as the time between calibrations has been illustrated in this paper. Adjusting the process continuously and calibrating it at the appropriate time can have major benefits when it comes to the process availability and utilization, increasing performance by 4.1-9.3 % in these cases. Evaluation of process robustness with regards to different maintenance strategies and process variation gave an indication of the process and unit performance under a long operating period. By combining discrete and dynamic simulation, a higher simulation fidelity can be achieved to provide a more operational perspective to the optimization and process analysis.
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| 2. |
- Bengtsson, Magnus, 1973, et al.
(författare)
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ADVANCED MATERIAL MODELLING IN CRUSHING PLANTS USING REAL TIME ALGORITHMS
- 2015
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Ingår i: Computational Modelling 2015, MEI conference.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In process control of crushing plants the traditional control is focused on stability control ofsingle machines and not on controlling material utilization. The reason for this is that the use ofmaterial property models is not that well known. The material models describe properties as e.g.capacity over time for a given product and this may depend on many parameters and dynamic effectsin the process. Due to this it is complicated to model and thus a methodology is needed to solve thisproblem. In this paper a novel method for modeling the current effect that the production units haveon the material presented. The paper presents a methodology how to use process data from SCADAsystem to analyze and suggest dynamic material model properties in real time.
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| 3. |
- 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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| 4. |
- Bengtsson, Magnus, 1973, et al.
(författare)
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Framework for material modelling in a processing plant
- 2015
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Ingår i: Computational Modelling ‘15.
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Konferensbidrag (refereegranskat)abstract
- Material modelling within a crushing plant is closely dependent on both manual and automatic operations as well as a close follow up on the utilization of the plant performance from a management perspective. The desire to fully be able to utilize the crushing plant with respect e.g. to material handling is limited due to the lack of possibility to fully observe actions within the process. There are large quantities of data that can be monitored in the crushing plant SCADA system. However the data collected are governed by the quantity of actual sensors in the process. The aim with this paper is to propose a method for how-to pre-process the automatically gathered SCADA data in order to fill up dynamic models for process simulations. There is a fundamental need to increase the resolution of how the crushing plant behaves. This will be structured as a framework for analysing and suggesting model improvements that will increase the utilization and decrease both manual operations and give better performance when controlling the process.
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| 5. |
- Davoodi, Ali, 1984, et al.
(författare)
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DEM Modelling and Simulation of Banana Screen Classification Efficiency
- 2015
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Ingår i: Minerals Engineering. - 0892-6875.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Banana screens are popular and frequently used in minerals processing. The screens are characterized by a high separation capacity and low maintenance need. The operation of screening usually takes place after crushing operation. The banana screens have multiple panels with variable slope which enables the feed material to flow rapidly resulting in a high screening rate. The difference between banana screens and other screens is that in banana screens the screen cut size varies with the changing slope of the decks. There are a number of factors affecting the screening operation; the deck panel slope progression, screen deck material, aperture shape, vibrational motion, open area, thickness of deck, feed rate and material properties.The aim of this paper is to simulate the screening performance by using the Discrete Element Method (DEM) and to analyse different motions that affect screening operation efficiency. Three decks with different slopes have been used and two different motions, linear and elliptical, have been evaluated at one feed rate. Figure 1 shows the overview of DEM simulation of screening process. Design of Experiment (DoE) has been used to evaluate the factors that control the value of parameters. The results show that the classification efficiency can be evaluated by conventional comparison between the feed particle size distribution and each of the product streams. The resolution of the model also enables the calculation of a critical efficiency criteria position along the screen deck. This position can be used to define a screening robustness factor. The passage probability and stratification behaviour can also be evaluated.
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| 6. |
- Davoodi, Ali, 1984, et al.
(författare)
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DEM simulation of banana screen performance
- 2015
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Ingår i: Proceedings, ;Minerals Engineerings Conference Physical Separation 2015 June 11-12...
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Banana screening is an important size classification component. The screens are characterized by a high capacity for separation. The operation of screening usually takes place after crushing operation. The shape of the banana screens causes the feed material to flow rapidly and the result will be faster screening rate. The difference between banana screens and other screens is that in banana screens the screen cut size varies with the changing slope of the decks. There are number of factors that affect screening operation like inclination of discharge, open area, thickness of deck and feed rate.The aim of this paper is to simulate the screener deck with the help of DEM Simulation and to analyze different parameters that affect screener operation efficiency and optimizing the screener so that it has the best performance during the wear life of the screen media. The one deck banana screen are simulated, the result show when the value of deck thickness and deck slope increase the probability of particles passage through the apertures will be decrease.
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| 7. |
- Evertsson, Magnus, 1967, et al.
(författare)
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Control Systems for Improvement of Cone Crusher Production Yield and Fatigue Life
- 2015
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Ingår i: Conference in Minerals Engineering 2015.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Control systems for cone and gyratory crushers were first introduced during the early 60ths. The common opinion is that if these systems are able to compensate for the wear of the crushing liners the production yield can be increased with 20-25%. Over the years these types of systems have been widely used but the theory behind the principles have not been thoroughly scientifically scrutinized and presented. Of special interest is the capability to protect the crushers from long term overloading commonly defined as fatigue.
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| 8. |
- Grunditz, Simon, 1990, et al.
(författare)
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Prediction of Collision Energy in the VSI Crusher
- 2015
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Ingår i: Proceedings; European Symposium on Comminution and Classification 2015 September 7-10.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- VSI crushers are established comminution machines often used for size reduction and to improve the sphericity of rock particles. Data collection and experimental observation inside VSI crushers remains difficult, leading to lack of understanding of the full extent of the particle dynamics inside a VSI crusher. The aim of this paper is to attempt to characterize the probability of collision of particles in relation to their distance from the rotor. By comparing the number of collisions at a given location with the overall amount of collisions, the probability of a collision event related to the distance a particle has travelled from the rotor can be estimated. The result is an increased understanding of VSI crushers and the particle collision behaviour inside of a VSI crushing chamber.
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| 9. |
- Grunditz, Simon, 1990, et al.
(författare)
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The Effect of Rotor Tip Speed of a Vertical Shaft Impactor on the Collision Energy Spectrum
- 2015
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Ingår i: Proceedings;Minerals Engineering Conference Computational Modelling 2015 June 10-11.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The increasing restrictions on natural aggregates have led to a demand for effective production of artificial sand and gravel. VSI crushers are established comminution machines often used in order to improve the sphericity of particles. Due to the difficulty in data collection, the full extent of the particle dynamics inside a VSI crusher has remained unexplored.The aim of this paper is to use DEM simulations to model a full-scale crusher, generate a realistic material flow and make a number of crusher tests with different rotor tip speeds. Each particle’s collision energy compared to its size will provide a spectrum which can be related to the probability of breakage. This will show how increasing rotational speed affects collisions and the impact energy of particles inside the crusher. The result is an increased understanding that can allow optimization and modeling of VSI crushers with higher accuracy.
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