| 1. |
- Evertsson, Magnus, 1967, et al.
(författare)
-
Optimisation Aspects of Compressive Crushing
- 2008
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Ingår i: Proceedings of the XXIV International Mineral Processing Congress. - 9787030227119 ; 1, s. 40-49
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Konferensbidrag (refereegranskat)abstract
- Compressive crushing is applied in crushing plants used in mineral, mining, and aggregate industry for fragmentation of rock materials. From a global perspective, the total volume of crushed rock is massive and corresponds to several billion tons. All societies have to fulfil a daily need of rock material products and its derivatives such as metals and minerals. The business for metals and minerals is global while the aggregates production is mainly a local industry.This paper presents a broader overview of optimisation with respect to product yield, use of natural resources and energy consumption. High level plant optimisation of compressive crushing plants is covered as well as real-time optimisation and optimisation of single production units. Each of three optimisation areas are presented and a discussion around how these three areas will be able to communicate with each other is given. Several models, e.g. process performance behaviour with respect to wear, as well as fitness functions can be common for all three areas. Well-defined and representative fitness functions are of the utmost importance in order to assure that the optimisation results reflect the production targets.It is concluded that great benefits can be achieved by linking together different areas of optimisation. The future for compressing crushing lies, without a doubt, in tailored processes both with respect to machines optimised for each customer, plant parameters and operation routines as well as an on-line adjustment, which takes into account current information and control possibilities.
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| 2. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
-
A Training Simulator for Crushing Plant Operators
- 2012
-
Ingår i: XXVI International Mineral Processing Congress (IMPC 2012: Innovative Processing for Sustainable Growth; New Delhi; India; 24 September 2012 through 28 September 2012). - 9788190171434 ; , s. 2164-2171
-
Konferensbidrag (refereegranskat)abstract
- Crushing plants are widely used around the world as a pre-processing step in the mineral and mining industries and as standalone processing plants in the aggregates industry. Despite automation and different advanced model predictive control a lot of the process is still managed by operators. The operators affect a lot of the performance. The numbers of the improvement they can achieve are at least as big as the advanced control algorithms’, today. Therefore it is also important to train the operators so they know how to behave in different situations. Models for crushers and other production units have been developed during the years and the latest add is the different units’ dynamic behavior being brought in, which gives the crushing plants dynamic time dependant performance. This can be used as a simulator for operators training. By connecting a Human Machine Interface (HMI) to a dynamic simulator with the models incorporated, a training environment for operators can be achieved. In this paper a dynamic crushing plant simulator implemented in MATLAB/SIMULINK has been connected to an HMI via a PLC. The HMI is placed in a control room at the university and complemented with monitors showing sequences from the process connected to the simulations, thus creating a realistic control room for training. In the created training environment the operators can be trained under realistic conditions. Simple training scenarios and how they could be simulated are discussed. Apart from the increased level of knowledge and experience among the operators, the time is an important factor. While a real crushing plant is still being built, the operators to be can already be trained, saving a lot of the commissioning time.
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| 3. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
-
An On-line Training Simulator Built on Dynamic Simulations of Crushing Plants
- 2013
-
Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 2405-8963. - 9783902823427 ; 15:1, s. 218-223
-
Konferensbidrag (refereegranskat)abstract
- Crushing plants are widely used around the world as a pre-processing step in the mineral and mining industries or as standalone processing plants for final products in the aggregates industry. Despite automation and different types of advanced model predictive control, many the processes are still managed by operators. The skill of the operators influences the process performance and thus production yield. Therefore, it is important to train the operators so they know how to behave in different situations and to make them able to operate the process in the best possible way. Different types of models for crushers and other production units have been developed during the years and the latest improvement is the addition of dynamic behavior which gives the crushing plants a time dependent behavior and performance. This can be used as a simulator for operators training. By connecting an Internet based Human Machine Interface (WebHMI) to a dynamic simulator with the models incorporated, an on-line training environment for operators can be achieved. In this paper, a dynamic crushing plant simulator implemented in MATLAB/SIMULINK has been connected to a WebHMI. The WebHMI is accessible via the Internet, thus creating a realistic control room for operators’ training. In the created training environment, the operators can be trained under realistic conditions. Simple training scenarios and how they could be simulated are discussed. Apart from the increased level of knowledge and experience among the operators, the time aspect is an important factor. While a real crushing plant is still being built, the operators to be can already be trained, saving a lot of the commissioning and ramp up time.
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| 4. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
-
Application of Design of Experiments (DoE) in Evaluating Crusher Circuit Performance
- 2023
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The configuration and the interaction between the crushers and screens enable aggregate producers to produce products that are in accordance with the applicable product certification. However, the performance of the system is seldom optimized for the given conditions and market demand. This paper aims to describe the experimental work and the results of quantifying the crusher and screen performance by applying design of experiments in a full-scale tertiary crushing process of an aggregate production plant with both standard belt-cut sampling as well with continuous processes monitoring. The research output is able to demonstrate that there exists an interaction effect between the crusher closed side setting and eccentric speed that previously has not been identified with traditional methods. The quantification of interaction between crusher and screen individual performance to the process performance have been demonstrated with both belt-cut samples and continuous process monitoring.
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| 5. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
-
Comminution process modelling from a sustainability perspective
- 2018
-
Ingår i: 11th International Comminution Symposium (Comminution '18). - 9781510883789
-
Konferensbidrag (refereegranskat)abstract
- Mining is one of the largest industries in the world and contributes largely to the environmental emissions as well as gross domestic product growth for many countries. The demand for sustainability in the industry is continuously increasing with efforts such life cycle assessment, circular economy and even fairtrade to improve the entire supply chain from different perspectives. The process of comminution is subjected to different conditions and will influence the performance of the process and utilization of resources. In this paper the aim is to simulate comminution circuit from an operational perspective with dynamic simulations to evaluate process performance and environmental impacts and to compare it to a cradle-to-gate process. By integrating the environmental impacts into the dynamic process simulations, a higher simulation fidelity can be achieved to provide an extended operational and environmental perspective to the process assessment.
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| 6. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
-
Development of a cognitive supporting operator training environment
- 2014
-
Ingår i: 27th International Mineral Processing Congress, IMPC 2014, Santiago, Chile, 20-24 October 2014.
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Konferensbidrag (refereegranskat)abstract
- In aggregate production and mining the operators are responsible for controlling and monitoring the process to maintain high plant throughput and safe operation. Operators have to make different decisions to control the process due to changed demand on the operation from both management and conditions of the process. The quality of the response and the time it takes for an operator to respond to altered demand relies on what information is available and the experience of the operator.In this work a dynamic simulation platform has been developed to be used for operator training. Models for representing production units and process control for plant simulations have been developed and implemented in MATLAB/SIMULINK to simulate time-dependent plant behavior. Stochastic and scheduled events are included using the discrete events simulation toolbox SimEvents. The human-machine interface was developed using the human-machine interface software ICONICS. The operators’ cognitive process, in interpreting the plants semantic, has been studied by observations and with informal interviews with operators. This was done to get information about the daily operation and the problems that occur in the process. By interacting with operators that experience different physical interactions with the process; more qualitative e-learning software for supporting operator training in a dynamic operator environment could be developed. The quality of the operator training environment was evaluated with a usability study that was performed with operators and others within the production.
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| 7. |
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| 8. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
-
Development of production and environmental platforms for the European aggregates and minerals industries
- 2024
-
Ingår i: Minerals Engineering. - 0892-6875. ; 206:2024
-
Tidskriftsartikel (refereegranskat)abstract
- Both quantification and communication of environmental impacts can create the foundation for improved sustainable production and decision-making. Without widespread information about site-specific environmental impacts, stakeholders cannot make a well-informed decision based on the local system boundaries. With organization-wide digital platforms, different aspects of production and management can be integrated and customized based on the organization's needs. This paper aims to give an overview of the development of three different process and environmental platforms, their purposes, system structure, system constraints and the applied framework. These respective platforms are being developed separately for the Swedish aggregates industry, the European aggregates industry and the European critical raw materials sector. The initial demonstrator can integrate site-specific information with a simulation-based allocation of resources and generate Life-Cycle Assessment and Environmental Product Declaration reports harmonized with the EN 15804 standard and the associated Product Category Rules.
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| 9. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
-
Implementation of Dynamic Simulation at Anglo Platinum
- 2014
-
Ingår i: 9th International Comminution Symposium 2014.
-
Konferensbidrag (refereegranskat)abstract
- The dynamics of process operation can be overlooked in design; often with considerable loss of throughput resulting from dynamic fluctuation and mismatch of units across a circuit. As a consequence, higher demand is on design of different control strategies. Designing a circuit with consideration of the implications an operation and control strategies have on the process is essential.The aim of this paper is to describe the modelling work done for this application and give an overview of the implementation of dynamic simulation platform at Anglo Platinum to support future debugging and tuning of the Advanced Process Control for a planned expansion. This paper builds on previous dynamic modelling work done at the Mogalakwena North Concentrator. The work is focused on system identification and the implementation of the Advanced Process Control algorithm in the dynamic plant model. The dynamic model of the plant was connected to the Advanced Process Control system and the response of the model validated against the behaviour of the plant.
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| 10. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
-
Importance of crusher control and cloud computing process monitoring of crushers
- 2019
-
Ingår i: IMCET 2019 - Proceedings of the 26th International Mining Congress and Exhibition of Turkey. ; 2019, s. 873-876
-
Konferensbidrag (refereegranskat)abstract
- The main task of a crusher control system is to keep production on a desired level while simultaneously protecting the crusher from overload and fatigue failure. A stable production can be achieved through control of the crusher's closed side setting (CSS), which implies compensation of the wear of the crusher liners. A further objective is to provide with the possibility to optimize operational performance and utilization. For an efficient system the sampling rate needs to be sufficiently high and the control and optimization algorithms need to be robust. In addition, and equally important, configuration of the electrical cabinet and wiring must be able to withstand the harsh environment over time. Modelling and simulation of cone crushers have been on-going at Chalmers University of Technology during the last 25 years. With time the research has expanded to include several different aspects of cone crusher operation, design optimisation, real-time control and product yield optimization. As a consequence, a strong need for dedicated control possibilities of cone crushers have risen. The requirement for precise control led to the development of a new system for cone crusher control which was named Crusher Control Unit or CCU. The system has been further developed by Roctim to provide an independent, modular and flexible development platform for different crusher types. A unique feature is that the CCU can be retrofitted to both Hydrocone type of cone crushers as well as to Symons type independent of brand or age of the crusher. In order to remotely monitor the crusher performance and retrieve data from the CCU a cloud based solution has been developed.
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| 11. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
-
Modelling Dynamic Behaviour of Storage Bins for Material Handling in Dynamic Simulations
- 2012
-
Ingår i: XXVI International Mineral Processing Congress (IMPC 2012: Innovative Processing for Sustainable Growth; New Delhi; India; 24 September 2012 through 28 September 2012). - 9788190171434 ; , s. 258-267
-
Konferensbidrag (refereegranskat)abstract
- Material handling is an essential part of the aggregate and mining industries. Mixing and blending of granular material can affect the grading and particle size distribution of the material leaving the system. Segregation and variability can cause problems in the downstream process while insufficient capacity will disturb upstream processes.Process plants utilize surge bins for handling recycle streams of material and act as a buffer for the process. The flow through the surge bin is usually controlled by a simple PID controller or PID controller in combinations with a plant-wide controller. Even though the surge bins play an important role of smoothening out the plant and creating a steady operating condition are they seldom included in plant simulations. This can lead to a number of problems in the form of decreased plant capacity, plant lockdown, and even operation units malfunctioning. The main objective of this study is to investigate the dynamic behavior in surge bins and develop a model more suitable for representing this behavior, which can occur during operation, for dynamic simulations. The proposed model adopts vertical layers which allow for flows between segments depending on the level of neighboring segments. This enables both the representing of segregation within the system and gives an indication on the effects from different inlet- and outlet placements. The proposed model was developed in Matlab/Simulink and validated against an actual bin with the total capacity of 700 m3 in platinum ore application. With the new bin model significantly higher fidelity and more accurate dynamic simulation results were achieved.
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| 12. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
-
Modelling & dynamic simulation of gradual performance deterioration of a crushing circuit - including time dependence and wear
- 2012
-
Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875. ; 33, s. 13-19
-
Tidskriftsartikel (refereegranskat)abstract
- The use of steady-state models in process simulation is a well-established method in many process industries. Designing a large crushing plant by relying on steady-state simulations alone will not generally provide the full picture of possible operational performance. The dynamics and variation between equipment and stochastic events can significantly reduce predicted plant performance. In order to dynamically simulate the crushing circuit, models for process equipment need to be further developed.The purpose of this paper is to create a wear function for an existing Particle Size Distribution model (i.e., a Swebrec-function) with data obtained from a real crusher operating at gradually increasing closed side settings. This is done to create an accurate and updated model of the crusher in which the transient consequences of wear are captured. The Swebrec-function and correlation model were implemented into simulation software with simulated events; this simulation was validated with actual process readings. Improved simulations were then attained with the developed functions.
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| 13. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
-
Modelling environmental impacts of aggregates with dynamic simulations
- 2017
-
Ingår i: Proceedings of the 15th European Symposium on Comminution and Classification (ESCC2017).
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Aggregates production is one of the largest industries in the world and contributes largely to the global environmental emissions. To estimate different product environmental footprint, the industrial standard is to use the life cycle assessment (Bart et al.) to quantify their impact on the environment. In 2011, the environmental product labels and declarations standard ISO14025 (EPD) was initiated to create transparent and comparable information for consumers. This is becoming increasingly common in Sweden for constructions and infrastructure projects, with certain limitations. The process of producing aggregates is subjected to different conditions and setup that will influence the performance of the plant as well as the utilization of energy.In this paper the aim is to simulate different processes for aggregate production from an operational perspective to evaluate process performance and environmental impact for different scenarios. The objective is to model and simulate the process with dynamic process simulations to capture the accumulated environmental footprint and its variation of the different product as they are produced. An approach for estimating the environmental footprint within established dynamic simulation platform is presented and demonstrated. The proposed modelling approach demonstrates a systematic way to evaluate the process performance and quantifying the life cycle inventory (LCI) for given conditions. The developed models can be used to optimize the different aspects of the operation depending on the defined objective function and the system boundaries. Simulating the process by manipulating configuration of the entire process has been illustrated in this paper. By integrating the environmental impacts into the dynamic process simulations, a higher simulation fidelity can be achieved to provide an extended operational perspective to the optimization and improve process analysis.
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| 14. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
-
Modelling of Discrete Downtime in Continuous Crushing Operation
- 2016
-
Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875. ; 98, s. 22-29
-
Tidskriftsartikel (refereegranskat)abstract
- © 2016 Elsevier Ltd 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 simulate the process from a more operational perspective to evaluate process performance and process optimum for different operations. 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. An approach for combining discrete event simulations with time-dependent simulations for process evaluation and optimization is presented. The proposed approach demonstrates a systematic way 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 and availability with regards to process specific factors and 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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| 15. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
-
Modelling of Discrete Downtime in Continuous Crushing Operation
- 2015
-
Ingår i: Computational Modelling 2015, MEI conference.
-
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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| 16. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
-
Modelling & Simulation of Dynamic Crushing Plant Behaviour with MATLAB-Simulink
- 2013
-
Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875. ; 43-44:Special Issue: SI, s. 112-120
-
Tidskriftsartikel (refereegranskat)abstract
- Every process is subjected to changes in performance and efficiency over time. These dynamics can originate upstream and be inherent through the process or occur anywhere in the downstream process. Traditional plant simulations are performed with steady-state simulation, which are limited to give the performance in an ideal situation. However, plant performance usually tends to deviate away from the predicted plant performance. These dynamics are usually consequences of an altered state of the plant due to factors such as natural variation, unmatched, inappropriate or degrading equipment performance and/or stochastic events. This paper presents a novel approach for simulating dynamic plant behavior and evaluating effects from process modification through dynamic simulations with MATLAB/Simulink. An example of an existing crushing circuit is used to illustrate the functionality and the advantage of using a dynamic simulator. The results and knowledge gained from the simulation can provide a base for optimizing a robust production output in the form optimal utilization, energy efficiency or higher product quality.
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| 17. |
- Asbjörnsson, Gauti, 1985, et al.
(författare)
-
Modelling & Simulation of Dynamic Crushing Plant Behaviour with MATLAB-Simulink
- 2012
-
Ingår i: 8th International Comminution Symposium.
-
Konferensbidrag (refereegranskat)abstract
- Every process is subjected to changes in performance and efficiency over time. These dynamics can originate upstream and be inherent through the process or occur anywhere in the downstream process. Traditional plant simulations are performed with steady-state simulation, which are limited to give the performance in an ideal situation. However, plant performance usually tends to deviate away from the predicted plant performance. These dynamics are usually consequences of an altered state of the plant due to factors such as natural variation, unmatched, inappropriate or degrading equipment performance and/or stochastic events. This paper presents a novel approach for simulating dynamic plant behavior and evaluating effects from process modification through dynamic simulations with MATLAB/Simulink. An example of an existing crushing circuit is used to illustrate the functionality and the advantage of using a dynamic simulator. The results and knowledge gained from the simulation can provide a base for optimizing a robust production output in the form optimal utilization, energy efficiency or higher product quality.
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| 18. |
- Bengtsson, Magnus, 1973, et al.
(författare)
-
ADVANCED MATERIAL MODELLING IN CRUSHING PLANTS USING REAL TIME ALGORITHMS
- 2015
-
Ingår i: Computational Modelling 2015, MEI conference.
-
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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| 19. |
- Bengtsson, Magnus, 1973, et al.
(författare)
-
Cost And Performance Optimization Of A Tertiary Crushing Stage
- 2015
-
Ingår i: ESCC 2015 Conference. - Göteborg : Chalmers University of Technology. - 9789188041012
-
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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| 20. |
- Bengtsson, Magnus, 1973, et al.
(författare)
-
Framework for material modelling in a processing plant
- 2015
-
Ingår i: Computational Modelling ‘15.
-
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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| 21. |
- Bengtsson, Magnus, 1973, et al.
(författare)
-
Model of banana screen for robust performance
- 2016
-
Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875 .- 1872-9444. ; 91, s. 66-73
-
Tidskriftsartikel (refereegranskat)abstract
- Screens are an important production unit in crushing plants. The performance of the screen is essential to the performance of the crushing plant. In this paper a mechanistic model of a banana screen is described and a novel model for screen deck configuration is presented. The developed model can be used for optimization of a screen so that it has the best possible performance with respect to different feeding conditions, in order to obtain a desired separation. The simulation results were compared to full scale test data and the conclusions from this comparison is that the screen model needs further parameters to handle the necessary screen deck configuration. An initial static model was derived to explain how the screen deck configuration will affect the screen efficiency. The modification of the screen deck parameters resulted in a better correlation both regarding size distribution and predicted capacity.
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| 22. |
- Bengtsson, Magnus, 1973, et al.
(författare)
-
Size and shape simulation in a tertiary crushing stage, a multi objective perspective
- 2015
-
Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875 .- 1872-9444. ; 77, s. 72-77
-
Tidskriftsartikel (refereegranskat)abstract
- There is increasing demand to optimise yield and increase capacity of crushing plants. Research in this area has resulted in the development of numerous optimisation tools, and recent research has shown that the quality aspects of production have great influence on the optimisation results. The quality 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 to analyse the parameters product capacity and quality is presented. As an example a cone crusher and a vertical shaft impact crusher (VSI) is simulated in a tertiary stage. The simulation shows how capacity and product quality for a range of products will be affected when a parameter is changed. The paper also shows how wear will affect product capacity and quality.
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| 23. |
- Bengtsson, Magnus, 1973, et al.
(författare)
-
Towards dynamical profit optimization of comminution circuits
- 2017
-
Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875 .- 1872-9444. ; 103, s. 14-24
-
Tidskriftsartikel (refereegranskat)abstract
- There is an increasing demand to optimize performance and profit of comminution circuits. Research in this area has resulted in the development of numerous optimization tools, and recent research has shown that the quality aspects of the production have a great influence on the optimization results. The quality, cost, profit and capacity of a product are influenced by several parameters, and in order to control all of these parameters it is necessary to use some sort of optimization algorithm. In this paper, a novel approach to apply e.g. cost, revenue, capacity and quality in order to perform a multi objective optimization with the ability to handle dynamic variations of a comminution is presented. The problem with optimizations in general is that the objective function used for optimization is reduced in complexity in order to save computational time. In a comminution process performance varies with time and in order to perform a correct optimization the objective function used must be able to handle this type of dynamic behavior. The process has a given set of constraints that represents the conditions normal in these type of comminution 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. In this step a dynamic response model is described that will be able to address the difficulties with optimizing dynamic systems. The next step in the optimization is the definition of the multi-objective optimization formulation including constraints for the optimization. Evaluating the result of the optimization in combination with a strategy for relaxing constraint can show how to increase overall productivity and still reach certain product properties. The conclusions made in this work are that multi objective optimization is essential when optimizing a comminution circuit against multiple objectives.
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| 24. |
- Bhadani, Kanishk, 1991, et al.
(författare)
-
Application of design of experiments (DoE) in evaluating crushing-screening performance for aggregates production
- 2024
-
Ingår i: Minerals Engineering. - 0892-6875. ; 209
-
Tidskriftsartikel (refereegranskat)abstract
- The configuration and the interaction between the crushers and screens enable aggregate producers to produce products that are in accordance with the applicable product certification. However, the performance of the system is seldom optimized for the given conditions and market demand. This paper aims to describe the experimental work and the results of quantifying the crusher and screen performance by applying the design of experiments (DoE) in a full-scale tertiary crushing process of an aggregate production plant with both standard belt-cut sampling as well with continuous processes monitoring. The results show the application of a simplified modelling approach using the design of experiments for the evaluation of crusher performance and circuit performance using experimental data. The research output is able to demonstrate that there exists an interaction effect between the crusher closed side setting and eccentric speed that previously has not been identified with traditional methods. The quantification of interaction between crusher and screen individual performance to the process performance has been demonstrated with both belt-cut samples and continuous process monitoring. Using a DoE, digital experiments can be planned for mapping and quantifying the performance of aggregate production.
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| 25. |
- Bhadani, Kanishk, 1991, et al.
(författare)
-
Application of Multi-Disciplinary Optimization Architectures in Mineral Processing Simulations
- 2018
-
Ingår i: 11th International Comminution Symposium. - 9781510883789
-
Konferensbidrag (refereegranskat)abstract
- Optimization is a pivotal point in distinguishing the competitiveness between industries that are developing, designing and operating products and processes. Mineral processing is an industry which operates various sub-processes and produces one or several products. The sub-processes involved are dynamic in nature and differs in discipline of operation. These dynamic sub-processes are sequentially integrated forming a mineral processing system. Currently, the developed simulations for the mineral processing systems have the potential to be used to design, operate and control mineral processing plants to an increased extent, but need broader optimization strategies to integrate multiple sub-processes involved. The scope of this research is to demonstrate application of multi-disciplinary optimization (MDO) architectures into a mineral processing simulation. A case study consisting of two sub-processes of comminution and classification circuits to produce aggregate products is used to demonstrate the application of MDO architectures. The MDO architectures are compared based on problem formulation, computational resources required and validity of the results. The optimization results using MDO architectures can be used to illustrate trade-offs between different sub-processes within the considered scope. The application of MDO architectures can facilitate the linking mathematical models of various disciplines such as comminution, and liberation in mineral processing simulation.
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| 26. |
- Bhadani, Kanishk, 1991, et al.
(författare)
-
Application of multi-disciplinary optimization architectures in mineral processing simulations
- 2018
-
Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875. ; 128, s. 27-35
-
Tidskriftsartikel (refereegranskat)abstract
- Optimization is a pivotal point in distinguishing the competitiveness of industries that are developing, designing and operating various products and processes. Mineral processing is an industry which operates various sub-processes and produces one or several products. The sub-processes involved are dynamic in nature and differ in the discipline of operation. These dynamic sub-processes are sequentially integrated forming a mineral processing system. Currently, the developed simulations for the mineral processing systems have the potential to be used to design, operate and control mineral processing plants to an increased extent, but need broader optimization strategies to integrate multiple sub-processes involved. The scope of this research is to demonstrate application of multi-disciplinary optimization (MDO) architectures into a mineral processing simulation. A simulation study consisting of two sub-processes of comminution and classification circuits to produce aggregate products is used to demonstrate the application of MDO architectures. The MDO architectures are compared based on problem formulation, computational resources required and validity of the results. The optimization results using MDO architectures can be used to illustrate trade-offs between different sub-processes within the considered scope. The application of MDO architectures can facilitate the linking mathematical models of various disciplines such as comminution, and liberation in mineral processing simulation.
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| 27. |
- Bhadani, Kanishk, 1991, et al.
(författare)
-
Application of Optimization Method for Calibration and Maintenance of Power-Based Belt Scale
- 2021
-
Ingår i: Minerals. - : MDPI AG. - 2075-163X. ; 11:4
-
Tidskriftsartikel (refereegranskat)abstract
- Process optimization and improvement strategies applied in a crushing plant are coupled with the measurement of such improvements, and one of the indicators for improvements is the mass flow at different parts of the circuit. The estimation of the mass flow using conveyor belt power consumption allows for a cost-effective solution. The principle behind the estimation is that the power draw from a conveyor belt is dependent on the load on the conveyor, conveyor speed, geometrical design, and overall efficiency of the conveyor. Calibration of the power-based belt scale is carried out periodically to ensure the accuracy of the measurement. In practical implementation, certain conveyors are not directly accessible for calibration to the physical measurement as these conveyors have limited access or it is too costly to interrupt the ongoing production process. For addressing this limitation, a better strategy is needed to calibrate the efficiency of the power-based belt scale and maintain the reliability of such a system. This paper presents the application of an optimization method for a data collection system to calibrate and maintain accurate mass flow estimation. This includes calibration of variables such as the efficiency of the power-based belt scale. The optimization method uses an error minimization optimization formulation together with the mass balancing of the crushing plant to determine the efficiency of accessible and non-accessible conveyors. Furthermore, a correlation matrix is developed to monitor and detect deviations in the estimation for the mass flow. The methods are applied and discussed for operational data from a full-scale crushing plant.
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| 28. |
- Bhadani, Kanishk, 1991, et al.
(författare)
-
Applied Calibration and Validation Method of Dynamic Process Simulation for Crushing Plants
- 2021
-
Ingår i: Minerals. - : MDPI AG. - 2075-163X. ; 11:9
-
Tidskriftsartikel (refereegranskat)abstract
- There is a need within the production industry for digitalization and the development of meaningful functionality for production operation. One such industry is aggregate production, characterized by continuous production operation, where the digital transformation can bring operational adaptability to customer demand. Dynamic process simulations have the ability to capture the change in production performance of aggregate production over time. However, there is a need to develop cost-efficient methodologies to integrate calibrations and validation of models. This paper presents a method of integrating an experimental and data-driven approach for calibration and validation for crushing plant equipment and a process model. The method uses an error minimization optimization formulation to calibrate the equipment models, followed by the validation of the process model. The paper discusses various details such as experimental calibration procedure, applied error functions, optimization problem formulation, and the future development needed to completely realize the procedure for industrial use. The validated simulation model can be used for performing process planning and process optimization activities for the crushing plant's operation.
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| 29. |
- Bhadani, Kanishk, 1991, et al.
(författare)
-
CDIO Course Development for Faculty in Raw Materials Programmes
- 2017
-
Ingår i: The 13th International CDIO Conference Proceedings, Calgary, Canada. - 1796-9964. - 9780889533998 ; , s. 315-326
-
Konferensbidrag (refereegranskat)abstract
- In Europe, the existing MSc programmes which are linked to the thematic Raw Material content often focus mainly on technical knowledge in itself, and students graduate as professionals who know how to solve pre-defined technical problems. Students in such programmes seldom practice entrepreneurial, communication and innovation skills at a level that is needed in working life. On the other hand, the CDIO Initiative has developed a framework for modernizing engineering education by introducing such skills and thinking into the technical programmes and courses. It is widely discussed in the CDIO community that one of the constraints in implementing CDIO is faculty staff professional development. CDIO standards 9 and 10 focus on the faculty development and competencies both in terms of pedagogic as well as learning methods to deal with personal and interpersonal skills, and product, process, and system building skills. In order to bring a change and implement CDIO into the Raw Materials programmes in Europe, a modular course for training in CDIO was developed and delivered for the faculty member in the Raw Materials sector. This paper accounts for the development of the faculty training course, and provides a unique perspective on the implementation of CDIO into raw materials related programmes capturing the different models of implementation from different universities’ programmes and courses. The various universities involved provide programmes and courses across the entire value chain of raw materials from mining and minerals processing to materials design, sustainability and recycling. This paper will serve as a reference for the educators to develop and implement CDIO education methods in specific disciplines as illustrated here in the field of raw materials related programmes.
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| 30. |
- Bhadani, Kanishk, 1991, et al.
(författare)
-
Comparative Study of Optimization Schemes in Mineral Processing Simulations
- 2019
-
Ingår i: IMPC 2018 - 29th International Mineral Processing Congress. ; 2019, s. 464-473
-
Konferensbidrag (refereegranskat)abstract
- Modelling and simulations for mineral processing plants have been successful in replicating and predicting predefined scenarios of an operating plant. However, there is a need to explore and increase the potential of such simulations to make them attractive for users. One of the tools to increase the attractiveness of the simulations is through applying optimization schemes. Optimization schemes, applied on mineral processing simulations, can identify non-intuitive solutions for a given problem. The problem definition itself is subjective in nature and is dependent on the purpose of the operating plant. The scope of this paper is to demonstrate two optimization schemes: Multi-Objective Optimization (MOO) using a Genetic Algorithm (GA) and Multi-Disciplinary Optimization (MDO) using an Individual Discipline Feasible (IDF) approach. A two stage coarse comminution plant is used as a case plant to demonstrate the applicability of the two optimization schemes. The two schemes are compared based on the problem formulations, types of result and computation time. Results show that the two optimization schemes are suitable in generating solutions to a defined problem and both schemes can be used together to produce complementary results.
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| 31. |
- Bhadani, Kanishk, 1991, et al.
(författare)
-
Development and implementation of key performance indicators for aggregate production using dynamic simulation
- 2020
-
Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875. ; 145
-
Tidskriftsartikel (refereegranskat)abstract
- Continuous process improvements are needed to maintain and run an industrial operation at a profitable state. An aggregates production plant consists of multiple process operations such as blasting, primary crushing, followed by secondary and tertiary crushing stages with an intermediate screening of products. Each of these processes can be operated with multiple objectives in mind of operators and plant managers. These objectives can be defined by varying terms like generating required throughput of the plant, maintaining equipment’s health, meeting customers’ demands, etc. The use of the term key performance indicators is recurrent in industry to formalise and represent these objectives of operation. Currently, the KPIs defined by the ISO 22400 standards are widespread for continuous improvements in the manufacturing industry and they are viewed as a support tool to measure improvements. The scope of this paper is to calculate relevant KPIs for an aggregates production plant using dynamic simulations. Further, the KPIs are implemented in a three-stage aggregate production plant using both real-time plant data and dynamic process simulation. The KPIs developed are useful for operators and plant managers to make decisions. The results show the relationship and dependencies of various equipment and process KPIs. The dynamic simulation has potential to be used as an exploration tool to identify the opportunities of improvement in aggregates processing using KPIs as a measure. The KPIs presented in the paper are based on ISO 22400 standard and have potential to be extended to similar processing operations such as coarse and fine comminution for minerals processing. Apart from the diagnostics application, the KPIs implemented in the dynamic simulation platform can be used to explore and optimize a crushing plant’s design and operations.
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| 32. |
- Bhadani, Kanishk, 1991, et al.
(författare)
-
Experimental and simulation-driven improvements for coarse comminution circuit using Plantsmith process simulator - A case study of Geita Gold Mine, Tanzania
- 2021
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Continuous improvements are a key aspect of driving an industrial process plant at a profitable state. The performance of the crushing plant is driven by each equipment’s (crusher, screen conveyors, bin, etc.) operation, raw material properties, operational strategies, control system, maintenance, and so on. To bring improvements for full-scale industrial units, a thorough investigation is needed. In the considered case study, a need was posed by the industry operating coarse and fine comminution circuit to investigate the opportunities for upscaling and downscaling of the plant capacity along with evaluating the performance of the existing circuit. The need is driven by the change in ore characteristics from the mining segment. As the decision’s in the industry is driven by the cost, it is important to find opportunities which will increase the profitability and produces a viable solution(s). The paper presents a methodological approach for evaluating the performance of the crushing plant by carrying out: • Physical investigation and observation • Experimental survey and laboratory data analysis • Evaluating historical production data • Simulation configuration and calibration in Plantsmith process simulator • Evaluating alternative concepts using Plantsmith process simulator The evaluation presents possible improvements in the existing plants, and alternative concepts with their opportunities and pitfalls. The results show that a methodological approach can bring a wide understanding of the plant operations and simulation tool is useful for evaluating operational scenarios. Also, multiple practical aspects are presented concerning the investigation process.
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| 33. |
- Bhadani, Kanishk, 1991, et al.
(författare)
-
Simulation-Driven Development for Coarse Comminution Process - A Case Study of Geita Gold Mine, Tanzania using Plantsmith Process Simulator
- 2021
-
Ingår i: Proceedings of the Design Society. - : Cambridge University Press (CUP). - 2732-527X. ; 1, s. 2681-2690
-
Konferensbidrag (refereegranskat)abstract
- A comminution process is a material size reduction and separation process which is primarily used in the aggregates and the minerals processing industry. Knowledge related to equipment’s operation, raw material properties, operational strategies, control system, maintenance, etc. is needed to design a capable plant. New needs are arising from the industry for existing operational crushing plants such as investigation for improvements, upscaling, and downscaling of the capacity. The paper presents an application of simulation-driven development for a crushing plant in an existing gold processing plant. Due to the change in ore characteristics and the need for optimizing the cost of operation, it is required to investigate the opportunities for improvement and alternative options for downscaling the capacity of the plant. A systematic process for configuring, developing, and evaluating alternative concepts using a process simulation tool is presented. The results show the process of generating knowledge for alternative crushing plant operation settings and how the choices can be selected and eliminated using boundary conditions. The evaluation presents possible improvements and alternative concepts with their opportunities and pitfalls.
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| 34. |
- Bhadani, Kanishk, 1991, et al.
(författare)
-
State of the Art in Application of Optimization Theory in Minerals Processing
- 2017
-
Ingår i: European Symposium on Comminution and Classification, Izmir, Turkey.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- There has been continuous development going over the past 40 years related to the creation of models and simulation techniques to predict the behaviour of equipment and processes in minerals processing. At the same time, application of optimization theory into such modelling and simulation schemes has been applied to generate knowledge to improved performances of the equipment and processes.Different optimization techniques have been applied to design and configure different equipment and processes, yet there are no well-established formulations to reproduce the results. The research is scattered and focused on the need and application of the specific equipment or process not utilizing the optimization’s full potential.The aim of this paper is to highlight the trends in development of optimization schemes in minerals processing. By understanding the state of the art in application of optimization theory into mineral processing will further pave the possibility to develop utility in this field. The paper presents two classification schemes: State of Development Stage and State of Application Area as a basis to classify research within optimization related to mineral processing. In order to make smart and strategic decisions in minerals processing operations, it is required to further develop optimization techniques into modelling and simulation schemes to extract the relevant information. The classification schemes can be useful in defining the future focus area for research and development.
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| 35. |
- Bhadani, Kanishk, 1991, et al.
(författare)
-
Student Perspectives on Video-Based Learning in CDIO-Based Project Courses
- 2017
-
Ingår i: The 13th International CDIO Conference Proceedings, Calgary, Canada. - 1796-9964. - 9780889533998 ; , s. 689-704
-
Konferensbidrag (refereegranskat)abstract
- This paper aims at demonstrating the applicability of video learning in CDIO based project courses and at evaluating to what extent it benefits students. The courses are Machine Elements (PPU210), Product Planning - Needs and Opportunities (PPU085) and Engineering Design and Optimization (PPU190) in the Mechanical Engineering programme at Chalmers University of Technology. The research was carried out by first creating a set of videos for selected topics in three courses. In total, 22 videos were created including topics such as “Benchmarking”, “SWOT”, and “Prototype lab equipment instructions”. The learning outcomes of the video lectures were mapped to the CDIO syllabus. A blended learning environment was developed, i.e. the videos were utilised as additional support alongside existing learning activities. The videos were then used in the courses and the students’ feedbacks collected through a dedicated questionnaire, the regular course evaluation survey, and in student-teacher group meetings during and after the courses. The collected data was analysed to produce inferences about the applicability and utility of the video lectures. The resulting analysis shows the students’ preferences regarding the evaluated video lectures and instructions. The students find videos more appealing compared to traditional lectures. One of the main benefits highlighted is the possibility of watching the videos in parallel to the design-build-test project execution rather having the classroom lecture only. This helps in reinforcing concepts, and results in less dependency on supervisors during the project execution. Videos proved to be suitable for creating a blended learning environment and improved the perceived learning experience for the students. In order to maximize student satisfaction and interaction with the videos, the videos should be short and closely aligned to the other learning activities. The paper also suggests future improvements to be carried out for video-based learning in the courses, and proposes an easy adaptable way for teachers to develop video material.
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| 36. |
- Bhadani, Kanishk, 1991, et al.
(författare)
-
Trade-Off Curves for Performance Optimization in a Crushing Plant
- 2023
-
Ingår i: Minerals. - 2075-163X. ; 13:10
-
Tidskriftsartikel (refereegranskat)abstract
- Operational flexibility in an aggregate production process is required to adapt to changes in customer demands. Excessive demand for a particular product fraction can lead to operational alteration wherein re-crushing of the existing larger-sized product fraction is necessary. The choice of re-crushing existing product fractions results in feed condition changes to the crusher. One common approach to producing the desired product is by varying the operation settings of a crusher in a crushing plant. However, knowledge of differences in operational performance for changing feed conditions in the circuit is required. This potentially leads to a problem of performance optimization based on the desired target product, available feed material and capability of the crusher. The paper presents an application of a multi-objective optimization method to generate multiple operational settings for the dynamic change in the operation condition in a crushing plant. Controlled experimental survey data with varying feed conditions are used to calibrate the crusher model using an unconstrained optimization problem solved using a gradient-based algorithm (Quasi-Newton method). Trade-off curves between various performance indicators of the crushing plant using a dynamic simulation platform are generated using multi-objective optimization using a non-gradient-based algorithm (genetic algorithm). The results of the application can help the operators and plant managers to make proactive decisions to steer the operation of the crushing plant towards the desired needs of the operation.
|
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| 37. |
- Davoodi, Ali, 1984, et al.
(författare)
-
Analysis of Screening Performance using Discrete Element Modeling
- 2017
-
Ingår i: Proceedings of the Conference in Minerals Engineering. ; 2017
-
Konferensbidrag (refereegranskat)abstract
- Screening is an important process in size classification of granular materials. It is a complex process due to the collision between particles and also a number of different operational parameters that effect the screening process. The aim of this paper is to evaluate screening performance in one of the LKAB crushing platforms. In this work an industrial vibration screen has been simulated by using Discrete Element Method (DEM). The simulations were validated with data from experiments and the screening performance has been analyzed by changing the parameters such as feeding rate. The result shows that DEM simulation is an effective tool for understanding the process of screening and because of the contact model between individual particles and particles and geometries the result is comparable with real process. It is shown that by increasing the feeding rate to 100 ton/h the screening efficiency can be improved by 20 percent.
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| 38. |
- Davoodi, Ali, 1984, et al.
(författare)
-
Application of the Discrete Element Method to Study the Effects of Stream Characteristics on Screening Performance
- 2019
-
Ingår i: Minerals. - : MDPI AG. - 2075-163X. ; 9:12
-
Tidskriftsartikel (refereegranskat)abstract
- Screening is a key operation in a crushing plant that ensures adequate product quality of aggregates in mineral processing. The screening process can be divided into the two sub-processes of stratification and passage. The stratification process is affected by the relative difference between various properties, such as particle shape, size distribution, and material density. The discrete element method (DEM) is a suitable method for analyzing the interactions between individual particles and between particles and a screen deck in a controlled environment. The main benefit of using the DEM for simulating the screening process is that this method enables the tracking of individual particles in the material flow, and all of the collisions between particles and between particles and boundaries. This paper presents how different particle densities and flowrates affect material stratification and, in turn, the screening performance. The results of this study show that higher density particles have a higher probability of passage because of their higher stratification rate, which increases the probability that a particle will contact the screen deck during the process.
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| 39. |
- Davoodi, Ali, 1984, et al.
(författare)
-
DEM Modelling and Simulation of Banana Screen Classification Efficiency
- 2015
-
Ingår i: Minerals Engineering. - 0892-6875.
-
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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| 40. |
- Davoodi, Ali, 1984, et al.
(författare)
-
DEM simulation of banana screen performance
- 2015
-
Ingår i: Proceedings, ;Minerals Engineerings Conference Physical Separation 2015 June 11-12...
-
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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| 41. |
- Davoodi, Ali, 1984, et al.
(författare)
-
Effects of screen decks' aperture shapes and materials on screening efficiency
- 2019
-
Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875 .- 1872-9444. ; 139
-
Tidskriftsartikel (refereegranskat)abstract
- Screening is a key unit operation for the large-scale separation of materials. There are certain different machine parameters and variables that affect the process of screening. The Discrete Element Method (DEM) is a suitable method to analyze parameters and variables. The main benefit of using the DEM for simulating the screening process is that, as a contact model, it provides the possibility of tracking each particle in the material flow and all collisions between particles and between particles and boundaries. There are different types of materials used for screening media, such as rubber and polyurethane, which are used in modular systems as a panel, and such as steel, which are used as a wire in the mesh. This paper presents how different materials used in screen decks affect the screening process. The materials' strength and elasticity have been examined in order to study how the aperture will change in different materials and how different shapes of the aperture and material of screening media affect the screening performance by analyzing the effect on material flow.
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| 42. |
- Davoodi, Ali, 1984, et al.
(författare)
-
Investigating the effect of the feeding arrangement on screen media wear and screening efficiency by using DEM
- 2021
-
Ingår i: Minerals Engineering. - 0892-6875. ; in press
-
Tidskriftsartikel (refereegranskat)abstract
- The discrete element method (DEM) is an effective tool for studying particles and equipment interactions in comminution and classification processes. Comminution and classification process performances are dependent on the operational conditions of different units. For screens, the performance of the particle separation is affected by the wear on the screening media. This work aims to study how screening performance, along the deck, is affected by different feeding arrangements, and how it influences screen media wear. A series of DEM simulations were configured to different feeding arrangements and validated with data from a crushing plant. The simulation results and process data show how screen media wear patterns can appear in a different section of the screen and how significant their effect is on the screening performance along the deck.
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| 43. |
- Davoodi, Ali, 1984, et al.
(författare)
-
The effect of different aperture shape and material of screen deck on screening efficiency
- 2018
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Screening is a key unit operation for the large-scale separation of materials. There are a number of different machine parameters and variables which affect the process of screening. The Discrete Element Method (DEM) is a suitable method to analyze all parameters and variables. The main benefit of using DEM for simulating the screening process is that as a particle contact model it gives the possibility to track each particle in the flow and all collisions between particles and between particles and boundaries. There are a number of different materials commonly used for screen media such as rubber and polyurethane which are used in modular systems as a panel and steel is usually used as steel wire mesh but sheet metal can also be used. This paper presents how different materials used in screen decks affect the screening process. The strength and elasticity has been examined in order to study how the aperture will change with different materials and also how different shapes of the aperture and the material of screen media affect the screening performance by analyzing different material flow.
|
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| 44. |
- Davoodi, Ali, 1984, et al.
(författare)
-
Validation of a DEM model of screening performance
- 2021
-
Ingår i: Minerals Engineering. - 0892-6875. ; in press
-
Tidskriftsartikel (refereegranskat)abstract
- The discrete element method (DEM) is particularly suited to modelling screening processes in the minerals processing industry, since the control and optimisation of screen processes are still limited due to a lack of their fundamental understanding and the number of different design variables and machine parameters that affect the processes. The advantage of using DEM for assessing screening performance is the possibility of visualising particle behaviour in three dimensions along with the screen media. This study shows how the DEM can be used to analyse different screen machine parameters and material properties for further development. The effects of operational conditions and geometry on the screen performance are studied by a series of DEM simulations and experimental tests using a special laboratory screen. The simulations of screen performance are implemented over a variety of structural parameters, including screen width, aperture size, inclination angle and motion type. The results are analysed by distributions of percentage passing and other flow information, such as particle volume and velocities along the screen deck and the particle size distribution. The simulation results are useful for the development of a better understanding of the process and the control of the screen to create a predictive simulation model that can be used in dynamic process simulations of crushing and screening plants.
|
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| 45. |
- Edelbro, Catrin, et al.
(författare)
-
European initiative on CDIO in raw material programmes
- 2017
-
Ingår i: Proceedings of the 13th International CDIO Conference in Calgary. - Calgary.
-
Konferensbidrag (refereegranskat)abstract
- One of five Knowledge and Innovation Communities (KICs), was launched in Europe in 2014and has its focus on exploration, extraction, mineral processing, metallurgy, recycling andmaterial substitution of raw materials. To reach the vision, where the European Union’sindustrial strength is based on a cost-efficient, secure, sustainable supply and use of rawmaterials, a new generation of skilled people entering industry, universities and researchneeds to be developed. Today’s technical MSc graduates in raw materials and especiallyprimary resources (i.e. exploration, extraction, mining and mineral processing and metallurgy)best suits large companies where they often act as specialists and experts. For small tomedium enterprises as well as for our future engineers other skills than technical arenecessary. As a part of the KIC Raw Materials, the education project “The implementation ofCDIO in raw material programmes” started in 2016. The project focuses, during 2016-2017,on (WP1) faculty- and (WP2) pilot case development. There are no academic institutes inEurope that have yet applied CDIO for primary resource related MSc programmes. Thispaper describes an education project within the KIC Raw material and presents key outputswith implementing CDIO in mining and metallurgy related programmes.
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| 46. |
- Ekström, Lars, 1959, et al.
(författare)
-
Intervertebral disc response to cyclic loading--an animal model.
- 1996
-
Ingår i: Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine. - 0954-4119. ; 210:4, s. 249-58
-
Tidskriftsartikel (refereegranskat)abstract
- The viscoelastic response of a lumbar motion segment loaded in cyclic compression was studied in an in vivo porcine model (N = 7). Using surgical techniques, a miniaturized servohydraulic exciter was attached to the L2-L3 motion segment via pedicle fixation. A dynamic loading scheme was implemented, which consisted of one hour of sinusoidal vibration at 5 Hz, 50 N peak load, followed by one hour of restitution at zero load and one hour of sinusoidal vibration at 5 Hz, 100 N peak load. The force and displacement responses of the motion segment were sampled at 25 Hz. The experimental data were used for evaluating the parameters of two viscoelastic models: a standard linear solid model (three-parameter) and a linear Burger's fluid model (four-parameter). In this study, the creep behaviour under sinusoidal vibration at 5 Hz closely resembled the creep behaviour under static loading observed in previous studies. Expanding the three-parameter solid model into a four-parameter fluid model made it possible to separate out a progressive linear displacement term. This deformation was not fully recovered during restitution and is therefore an indication of a specific effect caused by the cyclic loading. High variability was observed in the parameters determined from the 50 N experimental data, particularly for the elastic modulus E1. However, at the 100 N load level, significant differences between the models were found. Both models accurately predicted the creep response under the first 800 s of 100 N loading, as displayed by mean absolute errors for the calculated deformation data from the experimental data of 1.26 and 0.97 percent for the solid and fluid models respectively. The linear Burger's fluid model, however, yielded superior predictions particularly for the initial elastic response.
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| 47. |
- Evertsson, Magnus, 1967, et al.
(författare)
-
Control Systems for Improvement of Cone Crusher Production Yield and Fatigue Life
- 2015
-
Ingår i: Conference in Minerals Engineering 2015.
-
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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| 48. |
- Evertsson, Magnus, 1967, et al.
(författare)
-
Control systems for improvement of cone crusher yield and operation
- 2014
-
Ingår i: Proceedings of Comminution '14.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Gyratory and cone crushers are regaining interest and are becoming more frequently used in order to create more energy efficient comminution circuits. A typical example is found in coarse comminution circuits were HPGRs are used as a first milling stage. In this case the preparation of a suitable feed with a well-defined width of the particle size distribution and a controlled top size are of high importance. In turn, this emphasizes the importance of a stable and controlled operation of the preceding crushing stages. 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.With developments in electronics and plant control the crusher control systems have become more refined over the years. Though, there are sometimes conflicting interests in the control strategies between process requirements and crusher protection. In the paper an overview of the challenges, opportunities and existing control systems for cone and gyratory crushers is presented. A requirement specification for a system that is possible to fully integrate into modern plant control systems is outlined.
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- Evertsson, Magnus, 1967, et al.
(författare)
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Monitoring and validation of life time prediction of cone crusher with respect to loading and feeding conditions
- 2016
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Ingår i: Comminution 16. - 9781510826670 ; 904 (1 Vol)
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Konferensbidrag (refereegranskat)abstract
- The interest and need for compressive crushing in gyratory, cone and HPGR crushers are increasing since ores become more competent and more difficult to break. Compressive crushing is energy efficient as a consequence of the crushing principle and the imposed stress-state. The stress variations can be described by stress amplitudes and it is a known fact that many different materials, components and machines suffer from cyclic loading which shortens the service lifetime. This phenomena is explained by density variations of the particle beds in the equipment which in turn originates from particle segregation and feeding alignment. The phenomena is often called fatigue and the consequence is premature breakdowns and a relatively shorter lifetime than expected. In this paper, a previously developed theory for lifetime assessment of cone crushers will be used as a foundation for evaluation of full-scale operating cone crushers in minerals processing plants. Lifetime is calculated as a consequence of the load spectrum. The data shows that improper feeding conditions will substantially decrease the lifetime of the crusher equipment leading to excessive operating costs. An adequate control system should be able to recognise the hazardous lifetime decreasing overloads and to warn the operator. There are sometimes conflicting interests in the control strategies between production yield (process requirements) and crusher protection.
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