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Carl Magnus Evertsson - One of the best experts on this subject based on the ideXlab platform.
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Cone Crusher Performance
2020Co-Authors: Carl Magnus EvertssonAbstract:Cone Crushers are used by both the aggregate producing and the mining industry. Both industries are interested in increasing the product quality while at the same time lowering the production costs. Prediction of Crusher performance has been focused on, since crushing is a vital process for both industries. In the thesis a method for prediction of Cone Crusher performance is presented. The model is based on the laws of mechanics and constitutive relations concerning rock breakage characteristics. There are some crucial assumptions which are of central interest for the model. The validity of these assumptions has been verified by full-scale tests. The overall size reduction process is a result of several subsequent crushing events. Therefore, the process occurring in a Cone Crusher must also be modelled in the same repetitive way. Each crushing event is modelled with a selection and a breakage function. Selection corresponds to the probability of a particle being broken when an aggregate of particles is compressed. Breakage represents the way a single particle is broken into smaller fragments. The appearance of the selection and breakage functions is rock material specific and can be obtained by laboratory tests. The characterization of the fragmentation behaviour for rock materials is done by form conditioned compression crushing tests. Two modes of breakage are possible to achieve in a Cone Crusher. The location of the choke level is the criterion which determines the breakage mode. Interparticle breakage is achieved above the choke level while only single particle breakage is achieved below this level. The Crusher model takes the fragmentation behaviour of the rock and feed size distribution into consideration. Moreover, chamber and machine geometry, together with machine parameters such as closed side setting, stroke and eccentric speed, is accounted for. On all occasions continuity of mass is preserved. Three main factors are identified to promote the size reduction process occurring in a Cone Crusher. These factors are: breakage modes, number of crushing zones, and compression ratio. The main factors are affected by both design and operating parameters. For a given Crusher, the factors depend on eccentric speed, closed side setting, rock material breakage characteristics and feed size distribution. The main factors provide a fundamental and detailed understanding of how a Cone Crusher operates. Any design consideration should be evaluated against these main factors. The model can be used as a simulation tool to assist in the design process of Crushers. Any arbitrary design can then be studied. If a set of simulations is performed for a given Crusher, a Crusher Performance Map is achieved, which in turn can be used when optimizing a given crushing task or a crushing plant.
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Application of discrete element method for simulating feeding conditions and size reduction in Cone Crushers
2020Co-Authors: Johannes Quist, Carl Magnus EvertssonAbstract:The objective of this paper is to simulate the effects of segregation of the feed material entering the hopper on top of a typical Cone Crusher. A commercially available Discrete Element Method (DEM) software has been used to simulate and demonstrate some important aspects and phenomena and problems that are common in Cone Crushers. The first phenomenon of interest is segregation and uneven distribution of the feed entering a Cone Crusher. This is a common problem in many applications and leads to decreased comminution performance, poor product quality, uneven wear of the Crusher manganese liners, high stress amplitudes and premature fatigue failures. This problem has been observed in many different applications and can sometimes severely affect the Crusher performance in a negative way. A range of possible solutions to address the segregated feed is studied. The internal size reduction process occurring in a Cone Crusher is also modelled an simulated by applying DEM. The results of the simulations show the dynamics of the Crusher and the interaction of the rock material and the machine as well as the breakage and the size reduction process of the rock particles. The results from the DEM simulations of the crushing process are confirming earlier results retrieved by analytical models and simulations. The number of compressive crushing zones is confirmed to be around 10-11 in the studied Crusher. The capacity of the Crusher is controlled by the choke level. The two different breakage modes, inter and single particle, is clearly seen in the simulations. In addition, some new insights in the internal size reduction process are gained.
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Liner wear in jaw Crushers
Minerals Engineering, 2020Co-Authors: Mats Lindqvist, Carl Magnus EvertssonAbstract:Wear in rock Crushers causes great costs in the mining and aggregates industry. Change of the geometry of the Crusher liners is a major reason for these costs. Being able to predict the geometry of a worn Crusher will help designing the Crusher liners for improved performance. A model for prediction of sliding wear was suggested by Archard in 1953. Tests have been conducted to determine the wear coefficient in Archard's model. Using a small jaw Crusher, the wear of the Crusher liners has been studied for different settings of the Crusher. The experiments have been carried out using quartzite, known for being very abrasive. Crushing forces have been measured, and the motion of the Crusher has been tracked along with the wear on the Crusher liners. The test results show that the wear mechanisms are different for the fixed and moving liner. If there were no relative sliding distance between rock and liner, Archard's model would yield no wear. This is not true for rock crushing applications where wear is observed even though there is no macroscopic sliding between the rock material and the liners. For this reason, Archard's model has been modified to account for the wear induced by the local sliding of particles being crushed. The predicted worn geometry is similar to the real Crusher. A Cone Crusher is a machine commonly used in the mining and aggregates industry. In a Cone Crusher, the geometry of the crushing chamber is crucial for performance. The objective of this work, where wear was studied in a jaw Crusher, is to implement a model to predict the geometry of a worn Cone Crusher.
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Impact of Feeding Position on Power Draw and Size Reduction in a Cone Crusher
2018Co-Authors: Albin Gröndahl, Erik Hulthén, Johannes Quist, Gauti Asbjörnsson, Carl Magnus EvertssonAbstract:The power draw of Cone Crushers, used in comminution and aggregates production, is in most cases monitored with too low sampling rate in comparison to the operating speed. This does not give adequate information on the actual operation mode and performance of the Crusher during a full rotation of the eccentric motion of the mantle, leaving variance in the power draw unnoticed. This investigation has utilized a high speed measurement system for power draw on a lab scale Cone Crusher in order to identify an induced miss alignment in the feed, which is a common operation phenomenon, and the consequences of it. The results show that variations in the feeding alignment can be diagnosed and identified using only power draw measurements and that there are possibilities to use the approach for future control systems to improve fatigue life, operating efficiency, production yield and liberation in comminution processes.
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Investigation of High Speed Cone Crushing Using Laboratory Scale Experiments and DEM
2017Co-Authors: Marcus Johansson, Carl Magnus Evertsson, Johannes Quist, Erik HulthénAbstract:Cone Crushers are commonly used in secondary and tertiary crushing stages in comminution circuits. A multitude of factors and variables influence the performance in terms of throughput capacity, size reduction, power draw and wear. Crushers are normally installed and operated at a fixed eccentric speed setting. By installing variable frequency drives and realtime optimization algorithms Hulthen and Evertsson have shown that the eccentric speed can be used as a variable to optimize the yield and improve the performance. However, the influence of eccentric speeds above the normal operational range has been scarcely reported on in the literature. This paper aims at reporting on the result from an exploratory study where experiments and simulations have been used to evaluate Cone Crusher operation at high eccentric speed levels ranging from 10-40 Hz. A laboratory Morgardshammar Cone Crusher has been refurbished for the purpose of the study. A preliminary set of experiments have been performed where results showed that the chamber geometry has a vital importance. The same behaviour as observed in the experiments was also further understood by using DEM simulations leading to the design of a new chamber geometry. The new chamber design have been evaluated using DEM at four eccentric speeds and two different close side settings. The rock model has been calibrated by single particle breakage experiments and is based on the bonded particle model. The product particle size distribution has been estimated by image analysis of the bonded cluster discharge. The work addresses and shows results relevant to three areas in comminution and engineering research; Simulation driven design, DEM modelling, Cone Crusher theory.
Erik Hulthén - One of the best experts on this subject based on the ideXlab platform.
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Importance of Crusher control and cloud computing process monitoring of Crushers
2019Co-Authors: Gauti Asbjörnsson, Erik Hulthén, A. Bolander, Magnus EvertssonAbstract: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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Impact of Feeding Position on Power Draw and Size Reduction in a Cone Crusher
2018Co-Authors: Albin Gröndahl, Erik Hulthén, Johannes Quist, Gauti Asbjörnsson, Carl Magnus EvertssonAbstract:The power draw of Cone Crushers, used in comminution and aggregates production, is in most cases monitored with too low sampling rate in comparison to the operating speed. This does not give adequate information on the actual operation mode and performance of the Crusher during a full rotation of the eccentric motion of the mantle, leaving variance in the power draw unnoticed. This investigation has utilized a high speed measurement system for power draw on a lab scale Cone Crusher in order to identify an induced miss alignment in the feed, which is a common operation phenomenon, and the consequences of it. The results show that variations in the feeding alignment can be diagnosed and identified using only power draw measurements and that there are possibilities to use the approach for future control systems to improve fatigue life, operating efficiency, production yield and liberation in comminution processes.
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A Novel Approach to Cone Crusher Feeding using High frequency Power Draw Measurements
2017Co-Authors: Marcus Johansson, Magnus Evertsson, Erik HulthénAbstract:The Cone Crusher is one of the most widely used crushing machines in comminution circuits. The performance of the machine is heavily dependent on how it is fed. The performance of Cone Crushers is usually quantified by the three measures; throughput, power and particle size distribution. In this research, an adjustable feeding nozzle is controlled using an adaptive algorithm to position the feeder nozzle for improved feeding conditions. By processing high-frequency power data, an estimation of the power variance can be obtained, which is in this work studied to improve the feeding conditions of the Cone Crusher. Step responses as well as steady state power draw is compared and used to develop a new algorithm. An adjustable nozzle have been built and evaluated in a laboratory environment. The results are also compared to using a stationary feeder. The laboratory tests show promising results for applications where trickle feeding of Cone Crushers is preferable.
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Investigation of High Speed Cone Crushing Using Laboratory Scale Experiments and DEM
2017Co-Authors: Marcus Johansson, Carl Magnus Evertsson, Johannes Quist, Erik HulthénAbstract:Cone Crushers are commonly used in secondary and tertiary crushing stages in comminution circuits. A multitude of factors and variables influence the performance in terms of throughput capacity, size reduction, power draw and wear. Crushers are normally installed and operated at a fixed eccentric speed setting. By installing variable frequency drives and realtime optimization algorithms Hulthen and Evertsson have shown that the eccentric speed can be used as a variable to optimize the yield and improve the performance. However, the influence of eccentric speeds above the normal operational range has been scarcely reported on in the literature. This paper aims at reporting on the result from an exploratory study where experiments and simulations have been used to evaluate Cone Crusher operation at high eccentric speed levels ranging from 10-40 Hz. A laboratory Morgardshammar Cone Crusher has been refurbished for the purpose of the study. A preliminary set of experiments have been performed where results showed that the chamber geometry has a vital importance. The same behaviour as observed in the experiments was also further understood by using DEM simulations leading to the design of a new chamber geometry. The new chamber design have been evaluated using DEM at four eccentric speeds and two different close side settings. The rock model has been calibrated by single particle breakage experiments and is based on the bonded particle model. The product particle size distribution has been estimated by image analysis of the bonded cluster discharge. The work addresses and shows results relevant to three areas in comminution and engineering research; Simulation driven design, DEM modelling, Cone Crusher theory.
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Two Variable Real-Time Algorithm for Cone Crusher Control
2017Co-Authors: Erik Hulthén, Carl Magnus EvertssonAbstract:Cone Crushers are used in the mineral, mining, and aggregate industry for fragmentation of rock materials. Control systems for Cone Crusher setting (CSS) are widely used to compensate for wear and to protect the Crusher. With a frequency converter the eccentric speed in a Cone Crusher can be adjusted in real-time. The eccentric speed of the main shaft affects the number of compressions the material is exposed to and thus the capacity and the particle size distribution of the product. By applying mass-fl ow sensors to the process, a feedback of the different product yields is obtained in every moment. In this paper, a model and an algorithm are presented. The algorithm takes the incrementally increasing CSS into account and compensates for this with a successively changing eccentric speed. In order to implement the algorithm, a monitoring and control system is developed, including the online algorithm for selection eccentric speed. The different product fl ows from the crushing plant are continuously monitored by mass fl ow meters. The fi tness function is set by the plant management depending on production targets and market situation. An earlier developed Finite State Machine (FSM) algorithm is also implemented and evaluated in the system. The developed algorithm has been validated and verifi ed at a crushing plant for aggregates with a production of around 400 kton a year. The new algorithm is shown to increase the crushing stage throughput with 6.9 per cent. The FSM algorithm, on the other hand, increases the throughput with 5.3 per cent, which is a confi rmation of the magnitude of its benefi ts demonstrated in an earlier paper.
Simopekka Hannula - One of the best experts on this subject based on the ideXlab platform.
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the correlation of material characteristics and wear in a laboratory scale Cone Crusher
Wear, 2009Co-Authors: Paivi Kivikytoreponen, Sanna Alakleme, Jari Liimatainen, Jussi Hellman, Simopekka HannulaAbstract:Abstract Wear of materials is a widely recognised industrial problem. The direct costs of wear failures, such as wear part replacements, loss of productivity as well as indirect losses of energy, and the increased environmental burden, are real problems in everyday work and business. The mineral industry is particularly susceptible to wear part consumption resulting in high expenses. In this study, the performance of various steel-based wear resistant powder metallurgical metal matrix composites (MMCs) was studied for mineral industry applications. The matrix of the composites consisted of various tool steels, manganese steel and martensitic steel and the reinforcements used were tungsten carbides (WC), titanium carbides (TiC) or cemented carbides (WC/Co). Hot isostatic pressing (HIP) was used for compacting the materials. The performance of composite materials was studied in a laboratory scale Cone Crusher wear test. Correlations between the wear behaviour and microstructure parameters, such as volume fraction and the size of the hard particles and spacing between hard particles were investigated. It was found that the most important parameters in this wear environment were the total volume fraction of the hard phase and the type of the hard phase. A necessary feature of the matrix material is that it is also resistant to abrasion.
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abrasive wear properties of tool steel matrix composites in rubber wheel abrasion test and laboratory Cone Crusher experiments
Wear, 2007Co-Authors: Sanna Alakleme, Paivi Kivikytoreponen, Jari Liimatainen, Jussi Hellman, Simopekka HannulaAbstract:Abstract Abrasive wear is the most common type of wear phenomenon in mineral crushing industry. Tool steel matrix-based composites are an attractive choice to combat wear in those conditions because of their excellent abrasion resistance. One purpose of this study is to evaluate the abrasion resistance of such composites having different microstructures. Another purpose is to find out whether the simple dry sand rubber wheel abrasion test (ASTM G 65-91), which is a commonly used and relatively cheap and easy-to-perform test, could be used to rank materials for rock crushing although abrasive wear is not the only type of wear in the real rock crushing conditions. For this purpose Nordberg laboratory Cone Crusher test was used. Seven different composites were studied. The tool steel of type Ralloy®WR6 was used as a matrix material in all composites. The reinforcement was either cemented carbide (WC–Co), cast tungsten carbide (WC) or titanium carbide (TiC). The composites were manufactured by hot isostatic pressing (HIP). Abrasive wear properties of all the studied composites are very good. The reinforcement type, size, properties, volume fraction and reinforcement distribution in the matrix all influenced the wear results in both of the tests, but in a different way. Best wear resistance in Cone Crusher conditions was obtained with cemented carbide (WC–10Co) reinforced Ralloy®WR6 and in dry sand abrasion with WC reinforced Ralloy®WR6. No simple correlations between the dry sand rubber wheel abrasion test results and the Cone Crusher test results were found. This can be attributed to the different wear mechanics and consequently wear mechanisms in the two tests. In the dry sand rubber wheel abrasion test abrasion and detachment of the reinforcements are the major wear mechanisms while in the Cone Crusher abrasion with rock sliding and pure indentation are the major wear mechanisms. The differences in wear mechanisms result from differences in abrasives (type, size and hardness) and other wear conditions. It is concluded that dry sand rubber wheel abrasion test should not be used for screening materials for rock crushing applications as far as metal matrix composites are concerned.
Ian Lowndes - One of the best experts on this subject based on the ideXlab platform.
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discrete element modelling of a rock Cone Crusher
Powder Technology, 2014Co-Authors: Huiqi Li, Glenn R. Mcdowell, Ian LowndesAbstract:The feasibility of the discrete element method to model the performance of a Cone Crusher comminution machine has been explored using the particle replacement method (PRM) to represent the size reduction of rocks experienced within a Crusher chamber. In the application of the PRM method, the achievement of a critical octahedral shear stress induced in a particle was used to define the breakage criterion. The breakage criterion and the number and size of the post breakage progeny particles on the predicted failure of the parent particles were determined from the results of an analysis of the experimental data obtained from diametrical compression tests conducted on series of granite ballast particles. The effects of the closed size setting (CSS) and eccentric speed settings on the predicted product size distribution compare favourably with the available data in the literature.
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Discrete element modelling of rock communition in a Cone Crusher using a bonded particle model
Geotechnique Letters, 2014Co-Authors: Huiqi Li, Glenn R. Mcdowell, Ian LowndesAbstract:It is known that discrete element method modelling (DEM) of rock size reduction can be achieved by two approaches: the population balance model (PBM) and the bonded particle model (BPM). However, only PBM has been successfully used in DEM modelling Cone Crusher in the literature. The aim of this paper is to explore the feasibility of using the BPM to represent the size reduction of rock experienced within the Cone Crusher chamber. The feed rock particles were represented by isotropic dense random packing agglomerates. The simulation results were compared with the PBM simulation results, and it was shown that the BPM Cone Crusher model was able to satisfactorily replicate the performance of a Cone Crusher as well and it can provide more accurate prediction of the percentage of the fine products. In addition, the novel contribution here is that the rock feed material comprises particles of realistic shapes which break into more realistically shaped fragments compared with the fragments with defined shapes in the PBM model.
Magnus C Evertsson - One of the best experts on this subject based on the ideXlab platform.
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real time algorithm for Cone Crusher control with two variables
Minerals Engineering, 2011Co-Authors: Erik Hulthén, Magnus C EvertssonAbstract:Cone Crushers are used in the mineral, mining, and aggregate industry for fragmentation of rock materials, minerals and ores. Systems used for controlling the Closed Side Setting (CSS) on Cone Crushers, and thereby the size reduction, are widely used to compensate for wear of the manganese crushing liners and to protect the machines from overloads. With a frequency converter also the eccentric speed in a Cone Crusher can be adjusted in real-time in addition to the CSS. The eccentric speed affects the dynamic interaction between the rock material and the Crusher liners. Especially the number of compressions the material is exposed to is affected and also the local compression of the rock material is affected, thus the particle-size distribution of the product. Eccentric speed also affects Crusher capacity. Real-time feedback data on the sellable product streams can be obtained by applying mass-flow sensors to the process. The adjustment of these two online parameters in real-time can result in an increased potential for production yield; however, a nontrivial optimization problem with a large solution space also arises. As the feed material also varies, the optimal setting for the parameters varies in time. Herein, we report the development of a monitoring and control system including a two variable online algorithm for the selection of the setpoint for eccentric speed with respect to the current CSS. The different product yields from the crushing plant were monitored by mass-flow meters and continuously evaluated by a fitness function. A model for the outcome of the crushing stage, with the two parameters eccentric speed and CSS, was fitted mathematically to the measurement data. However, since the process varies continuously, due to the wear of Crushers and screens and feed material variations, the performance landscape is also continuously varying. Therefore, an Evolutionary Operation (EVOP) approach was adopted, wherein the variations are instead used to continuously find an operating point closest to the optimal. The developed algorithm was tested and evolved at a crushing plant for aggregates that produces around 400,000 tonnes aggregates per year. The algorithm was implemented in a computer that communicated with the frequency converter and retrieved data from ten mass-flow meters in the process. The operator was able to interact and supervise the system through a Human Machine Interface (HMI). The result is an algorithm that can determine the position and direction of a dynamic speed control to continuously improve the process-operation point. The magnitude of the improvement potential compared to a fixed speed operation is from 5% to 20%.
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algorithm for dynamic Cone Crusher control
Minerals Engineering, 2009Co-Authors: Erik Hulthén, Magnus C EvertssonAbstract:Cone Crushers are used in the mineral, mining, and aggregate industry for fragmentation of rock materials. Control systems for Cone Crusher settings are widely used for compensating for wear and protecting the machines from high pressure. However, these systems focus on the Crusher and not the crushed products. By applying measurement devices on the process the Crusher can be run optimally from the saleable products point of view (unlike most existing systems which only protect the machine) in each time. The measurement devices can be mass flow meters, e.g. conveyor belt scales. To analyze data from the process and convert them to a desired CSS value, an algorithm was developed. The developed algorithm is tested and evolved at a real crushing plant for aggregates. The algorithm was loaded into a computer which could communicate with the Crusher control system, read data from three mass flow meters, and also interact with the operators. The computer was reachable over the Internet by the researchers at Chalmers and the algorithm was tuned and improved on-line. The result is an algorithm which was capable of providing CSS set-points to the automatic setting regulation system. The amount of saleable product from the crushing stage improved 3.5%, when not limited by the hydraulic pressure, compared to when a fixed closed side setting is used. The use of the algorithm automatically compensates for changes in the feed material and it also decreases the need for calibration of the underlying system.