A computational methodology to calculate the required power in disc crushers

AbstractThis study aims to contribute to the estimation of power consumption in a disintegration process in disc crushers (fixed and mobile). The study covers the dynamic analysis of forces acting on the particles and the mobile disc. A detailed analysis of the resultant force on the particles was performed. Finally, the consumed power is calculated with the forces acting on the mobile disc. The calculated power is a key aspect in the design of disc crusher machines

Development of a methodology and validation of the Geopyörä breakage test

Abstract. Mining and metals industry extract, process and refine raw materials that are used in every aspect of modern society. It is also a priority sector to achieve a low carbon economy; commodities such as copper, cobalt, nickel and lithium, among others, are essential to developing clean energy technologies and electromobility plans. At the same time, the mining sector is energy-intensive and can have long-lasting impacts on the environment, depending on the exploitation method. Mining industry represents 7% of the worldwide energy consumption and contributes 10% energy-related greenhouse emission gases. In the latest reports, the actions took for the mining industry to achieve the Paris agreement goals were qualified as insufficient, a problematic scenario, considering that the targets are most likely increase during the next agreement. Comminution is the most power-demanding stage, using around 50% of the total consumption. In this context, optimisation in comminution processes is one of the biggest challenges in the industry. Geometallurgy is a discipline that aims to address the current challenges of the sector from an integrated mindset. Geometallurgical models from the perspective of comminution currently face a problem, the lack of a fast and reliable test to allow mapping the distribution of rock properties in ore deposits. The lack of information on comminution parameters contributes to inefficient comminution processes and consequently, higher energy consumption and emitted amounts of GHG (Greenhouse Gasses). This thesis work presents a methodology to perform breakage tests using a new device called Geopyörä. The research uses the parameters measured by the testing device to derive and validate comminution parameters such as JKDWT Axb, SMC Test® DWi and BWi. A methodology to achieve the objective of this test was created, allowing to have a procedure for a fast test, requiring approximately 10 minutes per sample, which ultimately results in a low-cost operation. This test uses less than a kilogram of a halve of a meter of drill core to obtain parameters of rock competence and hardness. The calculation and validation of parameters were carried out in comparison with tests widely used in the industry: JK Drop Weight Test, SMC Test® and Bond ball mill grindability test. The Geopyörä test could deliver reliable results for competence parameters, Axb and DWi (Drop Weight Index), within a margin of error of 7%. Additionally, a correlation between measured and BBMWi was also developed and validated. The results showed that the Geopyörä was also capable of measuring the Bond grindability parameter within an acceptable margin of error of 10%

A methodology for the design and evaluation of minerals extraction processes

Imperial Users onl

Comminution in the Minerals Industry

Size reduction processes represent a significant part of the capital as well as the operating cost in ore processing. Advancing the understanding of and improving such processes is worthwhile since any measurable enhancement may lead to benefits, which may materialize as reductions in energy consumption or wear or improved performance in downstream processes. This book contains contributions dealing with various aspects of comminution, including those intended to improve our current level of understanding and quantification of particle breakage and ore characterization techniques that are relevant to size reduction, as well as studies involving modeling and simulation techniques. The affiliations of the authors of the articles published in this book span 14 countries around the globe, which attests to the highly international nature of research in this field. The themes of the manuscripts also vary widely, from several that are more focused on experimental studies to those that deal, in greater detail, with the development and application of modeling and simulation techniques in comminution. Size reduction technologies more directly addressed in the manuscripts include jaw crushing, vertical shaft impact crushing, SAG milling, stirred milling, planetary milling, and vertical roller milling. Ores involved directly in the investigations include those of copper, lead–zinc, gold, and iron as well as coal, talc, and quartz

Unit Operations of Particulate Solids

Suitable for practicing engineers and engineers in training, this book covers the most important operations involving particulate solids. Through clear explanations of theoretical principles and practical laboratory exercises, the text provides an understanding of the behavior of powders and pulverized systems. It also helps readers develop skills for operating, optimizing, and innovating particle processing technologies and machinery in order to carry out industrial operations. The author explores common bulk solids processing operations, including milling, agglomeration, fluidization, mixing, and solid-fluid separation

16th European Symposium on Comminution and Classification: book of extended abstracts

Extended abstracts from the 16th European Symposium on Comminution and Classification, ESCC 2019 held at the University of Leeds, 2-4 September 2019. Based on the abstracts received, the symposium was structured in the following themes: fundamentals of size reduction, innovations in milling and classification, nanomilling, mechano-chemistry and solid state transformations, pharmaceuticals and foods, attrition and wear, and related modelling. The notable number of abstracts received on modelling made it possible to divide them in sub-themes: mechanistic, population balance, discrete element and coupling with computational fluid dynamics

The process mineralogy of selected Southern African uranium ores

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, December 2014.During the acid leaching of uranium, gangue-reagent interactions have both negative and positive consequences. Gangue dissolution increases reagent costs, and in some cases can prevent the economic acid leaching of an ore, but can also increase uranium mineral exposure and improve recoveries. Due to rapid dissolution kinetics, the acid consumption characteristics of the various carbonate species are readily predicted, however the same is not true of silicate gangue. Due to factors including slower leach rates, incongruent dissolution, parabolic kinetics, and surface area, pH and temperature dependence, the gangue acid consumption characteristics of silicate minerals are significantly more complex. A detailed mineralogical investigation and acid leach tests were conducted on sandstone- and granite-hosted uranium ore samples. The dissolution characteristics of the more common gangue phases were determined. The study demonstrated that gangue-reagent interactions and U dissolution can be predicted from mineralogical data. A model was developed which allows for the use of mineralogical and geochemical data to predict gangue reagent consumption. The basic framework of the model is universally applicable, but may require calibration, depending on the mineral assemblage and complexity of a specific uranium deposit

Discrete element method (DEM) modelling of rock flow and breakage within a cone crusher

A cone crusher is a crushing machine which is widely used in the mining, construction and recycling industries. Previous research studies have proposed empirical mathematical models to simulate the operational performance of a cone crusher. These models attempt to match the size distributions of the feed and product streams. The flow of the rock and its breakage within the cone crusher chamber are not explicitly modelled by these methods. Moreover, the ability to investigate the changes in crusher performance affected by changes to the crusher design geometry and/or operating variables (including cavity profile, closed size setting and eccentric speed) are not easily achieved. Improvements to system design and performance are normally achieved by the combination of iterative modifications made to the design and manufacture of a series of prototype machines, and from a subsequent analysis of the results obtained from expensive and time consuming rock testing programs. The discrete element method (DEM) has in recent years proved to be a powerful tool in the execution of fundamental research to investigate the behaviour of granular material flow and rock breakage. Consequently, DEM models may provide the computational means to simulate the flow and breakage of rock as it passes through a cone crusher chamber. Thus, the development of field validated models may provide a cost effective tool to predict the changes in crusher performance that may be produced by incremental changes made to the dimensions or power delivered to the crusher chamber. To obtain an improved understanding of the fundamental mechanisms that take place within a cone crusher chamber, the two processes of rock flow and rock breakage may be decoupled. Consequently, this study firstly characterised the flow behaviour of broken rock through a static crusher chamber by conducting a series of experiments to investigate the flow of regular river pebbles down an inclined chute. A parallel computational study constructed and solved a series of DEM models to replicate the results of these experimental studies. An analysis of the results of these studies concluded that an accurate model replication of the shape of the pebbles and the method used to load the pebbles into the inclined chute were important to ensure that the DEM models successfully reproduced the observed particle flow behaviour. These studies also established relationships between the chute geometry and the time taken for the loaded pebble streams to clear the chute. To investigate the rock breakage behaviour observed within a cone crusher chamber, thirty quasi-spherical particles of Glensanda ballast aggregate were diametrically crushed in the laboratory using a Zwick crushing machine. The crushed rock particles used were of three sieve size fractions: 14-28mm, 30-37.5mm and 40-60mm. The effects that either a variation in the particle size or strength has on and the number and size distribution of the progeny rock fragments produced on breakage were studied. Subsequently, a series of DEM simulation models were constructed and solved to replicate the experimental results obtained from these crushing tests. The aggregate particles were represented by agglomerates consisting of a number of smaller diameter bonded micro-spheres. A new method was proposed to generate a dense, isotropic agglomerate with negligible initial overlap between the micro-spheres by inserting particles to fill the voids in the agglomerate. In addition, the effects that a variation in the particle packing configurations had on the simulated strength and breakage patterns experienced by the model agglomerate rock particles were investigated. The results from these DEM model studies were validated against the experimental data obtained from the ballast rock breakage tests. A comparative analysis of the experimental and modelling studies concluded that once the bond strengths between the constituent micro-spheres matched the values determined from the rock breakage tests, then the numerical models were able to replicate the measured variations in the aggregate particle strengths. Finally, the individual validated DEM aggregate particle flow and breakage modes were combined to construct a preliminary coupled prototype DErvl model to simulate the flow and breakage of an aggregate feed through a cone crusher chamber. The author employed two modelling approaches: the population balance model (PBM) and bonded particle model (BPM) to simulate the observed particle breakage characteristics. The application of the PBM model was successfully validated against historical experimental data available in the literature. However, the potential wider use of the BPM model was deemed impractical due to the high computation time. From a comparative analysis of the particle size distributions of the feed and computed product streams by the two modelling approaches, it is concluded that the simpler PBM produces more practical computationally efficient numerical solutions

Laser cladding and its potential to reduce particulate matter emissions from the automotive and locomotive sector

Laser Cladding (LC) is an emerging technology which is used both for coating applications as well as near-net shape fabrication. Despite its significant advantages, such as low dilution and metallurgical bond with the substrate, it still faces issues such as process control and repeatability, which restricts the extension to its applications. The following thesis evaluates the LC technology and tests its potential to be applied to reduce particulate matter emissions from the automotive and locomotive sector. The evaluation of LC technology was carried out for the deposition of multi-layer and multi-track coatings. 316L stainless steel coatings were deposited to study the minimisation of geometric distortions in thin-walled samples. Laser power, as well as scan strategy, were the main variables to achieve this goal. The use of constant power, reduction at successive layers, a control loop control system, and two different scan strategies were studied. The closed-loop control system was found to be practical only when coupled with the correct scan strategy for the deposition of thin walls. Three overlapped layers of aluminium bronze were deposited onto a structural steel pipe for multitrack coatings. The effect of laser power, scan speed and hatch distance on the final geometry of coating were studied independently, and a combined parameter was established to effectively control each geometrical characteristic (clad width, clad height and percentage of dilution). LC was then applied to coat commercial GCI brake discs with tool steel. The optical micrography showed that even with preheating, the cracks that originated from the substrate towards the coating were still present. The commercial brake discs emitted airborne particles whose concentration and size depended on the test conditions used for simulation in the laboratory. The contact of LC cladded wheel with rail emitted significantly less ultra-fine particles while maintaining the acceptable values of coefficient of friction

Discrete element method (DEM) modelling of rock flow and breakage within a cone crusher

A cone crusher is a crushing machine which is widely used in the mining, construction and recycling industries. Previous research studies have proposed empirical mathematical models to simulate the operational performance of a cone crusher. These models attempt to match the size distributions of the feed and product streams. The flow of the rock and its breakage within the cone crusher chamber are not explicitly modelled by these methods. Moreover, the ability to investigate the changes in crusher performance affected by changes to the crusher design geometry and/or operating variables (including cavity profile, closed size setting and eccentric speed) are not easily achieved. Improvements to system design and performance are normally achieved by the combination of iterative modifications made to the design and manufacture of a series of prototype machines, and from a subsequent analysis of the results obtained from expensive and time consuming rock testing programs. The discrete element method (DEM) has in recent years proved to be a powerful tool in the execution of fundamental research to investigate the behaviour of granular material flow and rock breakage. Consequently, DEM models may provide the computational means to simulate the flow and breakage of rock as it passes through a cone crusher chamber. Thus, the development of field validated models may provide a cost effective tool to predict the changes in crusher performance that may be produced by incremental changes made to the dimensions or power delivered to the crusher chamber. To obtain an improved understanding of the fundamental mechanisms that take place within a cone crusher chamber, the two processes of rock flow and rock breakage may be decoupled. Consequently, this study firstly characterised the flow behaviour of broken rock through a static crusher chamber by conducting a series of experiments to investigate the flow of regular river pebbles down an inclined chute. A parallel computational study constructed and solved a series of DEM models to replicate the results of these experimental studies. An analysis of the results of these studies concluded that an accurate model replication of the shape of the pebbles and the method used to load the pebbles into the inclined chute were important to ensure that the DEM models successfully reproduced the observed particle flow behaviour. These studies also established relationships between the chute geometry and the time taken for the loaded pebble streams to clear the chute. To investigate the rock breakage behaviour observed within a cone crusher chamber, thirty quasi-spherical particles of Glensanda ballast aggregate were diametrically crushed in the laboratory using a Zwick crushing machine. The crushed rock particles used were of three sieve size fractions: 14-28mm, 30-37.5mm and 40-60mm. The effects that either a variation in the particle size or strength has on and the number and size distribution of the progeny rock fragments produced on breakage were studied. Subsequently, a series of DEM simulation models were constructed and solved to replicate the experimental results obtained from these crushing tests. The aggregate particles were represented by agglomerates consisting of a number of smaller diameter bonded micro-spheres. A new method was proposed to generate a dense, isotropic agglomerate with negligible initial overlap between the micro-spheres by inserting particles to fill the voids in the agglomerate. In addition, the effects that a variation in the particle packing configurations had on the simulated strength and breakage patterns experienced by the model agglomerate rock particles were investigated. The results from these DEM model studies were validated against the experimental data obtained from the ballast rock breakage tests. A comparative analysis of the experimental and modelling studies concluded that once the bond strengths between the constituent micro-spheres matched the values determined from the rock breakage tests, then the numerical models were able to replicate the measured variations in the aggregate particle strengths. Finally, the individual validated DEM aggregate particle flow and breakage modes were combined to construct a preliminary coupled prototype DErvl model to simulate the flow and breakage of an aggregate feed through a cone crusher chamber. The author employed two modelling approaches: the population balance model (PBM) and bonded particle model (BPM) to simulate the observed particle breakage characteristics. The application of the PBM model was successfully validated against historical experimental data available in the literature. However, the potential wider use of the BPM model was deemed impractical due to the high computation time. From a comparative analysis of the particle size distributions of the feed and computed product streams by the two modelling approaches, it is concluded that the simpler PBM produces more practical computationally efficient numerical solutions