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By G. G. Li

"A dynamic ventilation-modeling package, VREX, was used to simulate the mine activities through tracking the equipment movements in underground workings and determine the airflow demand for a new production scenario in a ventilation-on-demand (VOD) system. It incorporates the mine development data from a discrete event simulation and balances the ventilation network using the CANVENT ventilation solver. A case study was performed to demonstrate the capabilities of the software, evaluate the performance of the network and determine the potential energy savings for implementing VOD in a deep mine operation.INTRODUCTIONThe ventilation cost of an underground mine can be significant—up to 50% of the mine’s energy consumption could be used to run fans and provide heat/refrigeration to meet the specified production environment for workers and equipment. The VOD system has proven to be more efficient in operating the fans and supplying the amount of air corresponding to the mine activities taking place in underground workings (Hardcastle, Kocsis, & O’Connor, 2006). In order to properly solve and evaluate the VOD system, a dynamic ventilation modeling software VREX—the ventilation rules engine has been developed to simulate the mine activities and determine the airflow demand for each production scenario within an operation period (Dasys & Cameron, 2011).VREX is a decision support tool, backed by the CANVENT mine ventilation solver (Li, Kocsis, & Hardcastle, 2009), for determining the outcomes of network configuration changes over time. The software incorporates the mine development data with ventilation modeling through the discrete event simulation (DES) performed by SimMineTM. As it simulates the air requirements for different vehicles and activities, VREX can evaluate both the performance of the ventilation system and the potential economic benefits of making operational or technological changes (Pritchard, 2010). For example, the model can be used to assess the economic and environmental impacts arising from modifying regulations to support the use of electric or lower emission vehicles. The combination of DES and ventilation modeling provides a new technology to generate the production scenarios according to mine schedules and activities and to determine the potential benefits for various levels of ventilation control, such as time interval and work shift change."

Jan 1, 2019

By Pierre Roy, Claude Gosselin, Maryam Sadeghi, Michel Bourassa, Christian Rochefort, Claude Bazin, Gautier Mahieu, François Lavoie, Marilène Renaud, David Cataford

"Spirals are gravity concentrators used for the concentration of iron oxide minerals from ores. This paper presents the mineral size recovery curves observed for spirals operating in two Canadian iron ore processing plants. The size recovery curves are presented for rougher, cleaner and re-cleaner spirals. The partition curves observed for the spirals are significantly different than those observed for typical gravity concentration devices such as hydrocyclones or hydraulic classifiers. The size recovery curves show the complex behaviour of the minerals as they flow down a spiral and are analysed with a view toward process modelling and simulation. Initial simulation results show that gains in the iron recovery can be achieved by increasing the recovery of coarse iron oxide particles in the rougher spirals.INTRODUCTION Spiral concentrators are gravity based separation devices used for the preparation of coal, iron and different heavy minerals ores (Wills, 1992). The classification of the particles in spirals is based on the combination of gravity, centrifuge, drag, lift and Bagnold forces (Atasoy and Spottiswood, 1995; Burt, 1984; Bouchard, 2001). Several papers are dedicated to the analysis of the forces acting on the particles flowing down a spiral (Das and al., 2007; Sivamohan and Forssberg, 1985; Holland-Batt and Holtham, 1991; Holtham , 1992). Most of these papers aim at the development of a general model for the simulation of the classification of the particles for coal ore processing. Few papers deal with the operation of spirals for processing iron ores (Hyma and Meech, 1989; Srivastava, 2001; Dallaire et al., 1978) and fewer papers present results for spirals used as cleaners following a rougher stage. Since the classification in spiral classifiers is dependent on the particle size and specific gravity a partition or performance curve commonly applied to classifiers (Mai Manga et al., 2012) is used here to analyse spiral operation. Few papers were found to describe the operation of spirals in terms of partition curves (Atasoy and Spottiswood, 1995; Holland-Batt and Holtham, 1991; Richards et al., 2000). Most of the investigations presented the application of a model to simulate the position of coal particles of various sizes and specific gravities along the trough of a spiral (Kapur et al., 1996; Holland-Batt and Holtham, 1991). In addition most of the available literature on spirals deals with one stage of concentration by spirals (Dallaire et al., 1978; Das and al., 2007; Sivamohan and Forssberg, 1985) while industrial circuits usually consist of rougher and cleaner spirals."

Jan 1, 2014

By Hossein Aminian, Daniel Hodouin, Claude Bazin, Claude Jacob

"Solvent extraction followed by electrowinning (SXEW) is an economical option for the processing of low grade and oxidized copper ore. Phenomenological models were developed to simulate the copper solvent extraction and the electrowinning processes. The two models were linked together to make a SX/EW simulator. The simulator is used to predict the operation of the mines Gaspe pilot plant put in operation in 1996. Results confirm the potential of the simulation that would subsequently be used for student training, process optimization and to assess the performances of control strategies.INTRODUCTIONSolvent extraction followed by electrowinning (SXEW) has become in the last two decades a key process for the recovery of copper from solution obtained by leaching low grade copper ore. Several operations have been commissioned in North and South Americas in the last decade (Arbiter, 1994). In Canada, Gibraltar Mine (Scott, 1991) operates a SX plant followed by electrowinning (EW) to produce copper cathode from leached low-grade ore dumps. From 1996 to 1997 Mines Gaspe operated a pilot plant to test the economical feasibility of leaching an oxidized copper ore, followed by solvent extraction and electrowinning of copper. Despite copper SX/EW processes have the reputation of being low cost operations, plant engineers should always look at way to make the plant more efficient. Process models provide an economic platform to learn, control and ultimately optimize the operation of a plant.Several models have been independently proposed to simulate the SX process (Cadman and Hsu, 1970; Medina Gomez, 1980; Wilkinson and Ingham, 1983; Garcia et al., 1988; Aminian et al., 1997) and the EW process (Bryson, 1981; Barton and Scott, 1992; Barton and Scott, 1993). However few papers, if any, deal with the integration of the two process models into a single simulator of a SX-EW plant. This paper describes the development of an integrated simulator for the SX-EW process and shows some steady-state simulation runs of an actual SX-EW pilot plant. The paper consists of four sections. The first section shows the general layout and principles of operation of a SX-EW plant.The second section describes the SX model while the third section deals with the process model used for the copper electrowinning process. The last section shows how the two process models are linked to simulate the operation of the Gaspe pilot plant."

Jan 1, 1999

By Navid Bahrani

The grain-based model (GBM) has resolved the difficulty of matching both the directtension (sc) and unconfined-compressive (st strengths of typical brittle rock by providing a synthetic material that mimics deformable, breakable polygonal grains cemented along their adjoining sides with deformable, breakable interfaces modeled as smooth-joint contacts. In this paper, a GBM utilizing a parallel-bonded base material is calibrated to match both st and sc of Lac du Bonnet granite and then used to simulate a Brazilian test. The Brazilian strength (sB) is slightly overestimated and the failure mode includes ductile post-peak response that is not representative of what occurs in laboratory Brazilian tests. By reducing the grain tensile strength, grain failure occurs during the Brazilian test and a more realistic failure mode that includes brittle post-peak response is obtained. However, the unconfinedcompressive strength of the modified material is too low. Sensitivity analysis on the grain and grainboundary strength properties demonstrates that the grain tensile strength controls the sB/sc ratio. Because the grain strength is controlled by the parallel-bond properties and the lowest achievable st/sc ratio in a parallel-bonded material is ~0.25, it is concluded thatsc, st and sB for a typical brittle rock cannot be matched with a GBM that utilizes a parallel-bonded base material.

Jun 1, 2012

By S. Duvah Pentiah

The transformation of an open pit coal mine to a horizontal-punch underground mine is subject to a number of challenges. These include scheduling the operation of various sizes of trucks over a long period, as well as updating delivery routes and dump site locations as the mine transformation progresses. In this process, rock is excavated from a quarry through earthworks. The bulk earthwork and quarry material delivery were initially drawn from traditional planning and experienced issues in their early phases. As a result, a traffic simulator was developed in order to validate schedules and predict achievable throughput, likely delays or blockages in the long term. The dynamic traffic simulator was also used to provide traffic density and vehicle arrival data at selected intersections in order to identify possible safety and efficiency issues.

Aug 1, 2013

By N. Shi, T. G. Joseph

ABSTRACT: An interactive cable shovel simulation has been developed to mimic any shovel dipper geometry for a given cable shovel operating in any homogeneous face material. This interactive cable allows the user to predict shovel performance in any face material encountered and track both its ground stability and the dipper-ground interaction. An embedded Microsoft® Visual Basic spreadsheet was used as the platform for developing an interactive simulation that allows for maximum user-defined parameter input and interactive visual output. The result is an analytical dipper-ground interaction solution that yields crowd, hoist, and digging effort as a function of face activity position.

Jan 1, 2011

By Donald Leroux, Colin Hardie

"New or improved mathematical models of mineral processing machines are published almost on a monthly basis. Often, these models can be calibrated from bench-scale test results and programmed using spreadsheet software to simulate different designs and operating conditions in open-circuit configuration. However, since mineral processing plants frequently operate comminution, separation and/or extraction machines in closed-circuit configurations, open-circuit simulations often have limited applicability.The simulation of closed-circuit configurations necessitates the programming of an iterative loop to bring the circuit to equilibrium. This can be done by using spreadsheet software but often requires advanced programming skills. As an alternative, LIMN® software, which simplifies the programming of closed-circuit configurations within spreadsheets can be used. This software was specifically designed to turn a Microsoft EXCEL® spreadsheet into a closed-circuit modeling and simulation platform with minimal programming.During the past few years, the Mineral Processing Group at the Noranda Technology Centre, has used this software for numerous projects which include the simulation of multi-stage cyclone circuits, closed-circuit regrinding and locked-cycle flotation tests. Using these projects as examples, the flexibility and the easy to use nature of the LIMN® software is demonstrated.INTRODUCTIONMineral processing engineers routinely have to make predictions regarding comminution and separation processes. Predicting the appropriate dimensions of equipment and the process response to changes in operating mode are probably the most common situations that they face. In all cases these predictions are expected to be rapid and accurate.Predictions made by engineers are frequently based on mathematical models. Many first principles, empirical, semi-empirical, steady state and dynamic models of mineral processes can be found in the literature. In fact, new or improved mineral processing models are continuously being proposed and in spite of this variety, process engineers often have to either develop their own or tailor existing models to suit their particular needs."

Jan 1, 2003

By R. Noorani, M. Cai

"Excavation of deep underground openings in highly stressed grounds can generate new fractures near the openings. As a result, rock mass bulking may occur, leading to large wall deformation. A better understanding of brittle rock failure and the associated fracturing process at the laboratory scale is an essential step towards evaluating dilation behavior of rocks. A grain-based model that can capture dilation behavior of rocks under various loading conditions at the laboratory scale can be a useful approach to study rock mass bulking at the field scale. The aim of the paper is to study the dilation behavior of rocks at the laboratory scale employing numerical simulation. A modified grain-based model is used to simulate the macroscopic response of crystalline rocks by considering micro-fractures at the grain scale. Grains generated with the Voronoi tessellation are allowed to fail in tension or in shear using a strain-softening model. Damage is represented by either grain boundary fracture or grain failure, or the combination of the two. As stress increases, the process of damage, fracture initiation and coalescence in rocks can be captured.The grain-based model was calibrated using test data of the Lac du Bonnet granite and a parametric study was conducted. Numerical simulation results showed that the proposed modeling approach is able to capture most of the mechanical properties, fracture pattern, and dilation behavior in both unconfined and confined loading conditions. In an unconfined compression test, interactions of microscopic fractures may lead to macroscopic shear or axial splitting failure depending on the chosen micromechanical parameters. Numerical experimental results show that the dilation behavior of the model is strongly related to the failure mechanism of rocks. Tensile-failure-dominated failure mode generates large dilation due to the formation of new cracks that are sub-parallel to the loading direction. On the other hand, shear-failure-dominated failure mode produces small volume increase. One significant finding from this study is that in order to capture large dilation using grain-based UDEC models, intragranular grain failure should be considered."

Jan 1, 2015

By A. Gakwaya, P. Vachon-Joannette, P. Gagnon, J. Lévesque

"Predictive numerical methods are essential tools for reduced development cost and improved high performance designs of modern aircrafts. Their use leads to savings in terms of design cycle time and experimental trials. Composite materials subjected to impact loadings demonstrate various damage modes such as matrix cracking, fiber breakage, delamination and, ultimately, fabric fracture. Composite laminates are extensively used in the aerospace industry, and their damage modeling is complex due to their inhomogeneity and anisotropic behavior. Damage evolution affects both in-service properties and performance of these composites. In this work, the drop-weight impact test has been simulated. Using a material model that accounts for both delamination and intralaminar damage, laminates response is analysed using numerical simulations based on 3-D finite-element models of the commercial code Abaqus/Explicit. Experimental and simulation results are compared, in terms of energy absorption and contact force. The obtained numerical results show good agreement with experimental data.INTRODUCTIONAs primary aircraft structures are increasingly being made from advanced fiber-reinforced polymer matrix composites and are in general exposed to a variety of impact scenarios (bird, hail, debris etc.), an understanding of the impact event and the performance of composite materials during impact is important in the development of new structures. This work is focussed on low velocity impacts that typically occur when foreign objects hit the aircraft during maintenance or other on-the-ground operations. These impacts can cause non visible damage that affect the structural integrity of the composite components. While for metallic structures, damaging impact events typically leave noticeable dents due to plastic deformation, in contrast, for high strength carbon fiber reinforced composites, they can deform elastically to strain levels exceeding 1% and the internal damage can often occur without the formation of a visible dent. The identification and effect of impact damage on the performance of the structure is thus of great concern to the aircraft industry as the durability and damage tolerance of these composite structures are strongly influenced by the size of detectable internal damage."

Jan 1, 2016

By A. Ockewitz, A. Trondl, D. -Z. Sun

"Numerical simulation of extrusion processes offers an efficient method for tool design and optimization of geometries and properties of extruded parts. However, until now there are few systematic investigations about influences of material model and different parameters e.g. for friction and thermal processes on calculated local and global responses. Since extrusion processes are essentially influenced by friction between billet and extrusion tools, new friction tests were performed in this work to develop a reliable friction model. Compression and torsion tests were performed at different temperatures and velocities to calibrate the material model for extrusion simulations. Extrusion processes for circular rods and U-profiles were conducted at TU Berlin with backward and forward extrusion for different extrusion ratios, billet temperatures, product velocities and cooling conditions. This work focuses on numerical simulations of the extrusion tests with the FE code HyperXtrude. Based on the calculated distributions of local strain, strain rate and temperature the recrystallized volume fraction and grain sizes were calculated with empirical models and compared with the experimental results from optical micrographs and EBSD scans. The calculated total and friction forces and temperatures were compared with the experimental results and the deviations between experiment and simulation were analyzed.INTRODUCTION Extruded aluminum components are widely used in vehicle constructions due to light weight and manufacturing consideration. Local mechanical properties in the components are inhomogeneous as a consequence of the spatial distribution of microstructure which is influenced by numerous factors like material composition, temperature, tool design, friction, extrusion ratio and speed during the extrusion process. For the optimization of the extrusion process with regard to all these factors numerical simulation can be an essential tool. Based on results of finite element simulations of the extrusion process the microstructure in the extruded components can be predicted and then the resulting mechanical properties can be numerically determined instead of by costly trial and error methods. The aim of the work presented in this paper is the development of a numerical method for the simulation of extrusion processes with modeling of microstructure."

Jan 1, 2018

By Guangyuan Li

A 3-D block-spring model (BSM) has been developed for simulating the behaviour of jointed rocks. The model uses a discontinuous formulation and an iterative procedure to solve the large displacements in jointed and faulted rock masses. The 3-D BSM has been used to simulate mining excavations in jointed rocks around an open pit and underground settings. The applications have demonstrated that it is a practical tool to solve complicated problems of rock mechanics in civil and mining engineering. This model has recently been modified to incorporate complex geological conditions, such as underground water flow (seepage), unstable blocks and the time-dependent behavior of backfill materials. To demonstrate the capability of the 3-D model this paper presents the fundamentals of the 3- D BSM and its application for open-pit mining. A complete computer package BSM3D has been developed based on the 3-D block-spring model. The package consists of a solving engine for numerical analysis and a Windows based processor for mesh generation and results display. The multi-functioned pre-processor provides tools and menus to help users setting up models easily and conveniently. The fully featured post-processor allows users to view the results in different windows and orientations. The graphical results include contours, vectors, animation of rock movement, and the failure state of the rock structures.

May 1, 2001

By J. C. Kurnia

Methane is recognized as one of the prime causes of underground mine disasters around the globe. A cost-effective mine ventilation system and methane control is required to ensure a safe and productive environment in an underground mine whilst keeping energy usage and operating cost at minimum. Typically methane enters a mine environment or tunnel from localized distributed sources at high initial concentration. Hence, an understanding of its dispersion from discrete sources is important to design a methane management system via effective ventilation. This study employs computational fluid dynamics to model methane dispersion in an underground tunnel which has a number of discrete sources of methane and effective ways to dilute and or disperse it. Air flow distribution within the tunnel as well as methane dispersion is simulated by solving the governing transport equations subject to appropriate boundary conditions. First, the effectiveness of ventilation duct placement is examined. Several possibilities are explored and investigated. It is found that the common configuration utilized in underground mine performs best as compared to other configurations in maintaining the concentration of methane below permissible levels. Next, a novel intermittent airflow ventilation system is proposed and evaluated via simulation with the goal of reducing the energy cost whilst maintaining methane level in the mining face below the allowable level. Parametric studies are conducted to investigate effects of various factors influencing the effectiveness and performance of this novel intermittent ventilation system. This study will provide some new ideas for designing an efficient and effective underground mine ventilation system by lowering the net average amount of air that needs to be circulated in the tunnel for a safe operation. KEYWORDS

Aug 1, 2013

By J. D. Zhu

A numerical model for predicting microporosity formation in aluminum castings has been developed, which describes the redistribution of hydrogen between solid and liquid phases, the transport of hydrogen in liquid by diffusion and Darcy flow in the mushy zone, One of the key features of the model is that it uses a two-stage approach for porosity prediction, In the first stage, the volume fraction of porosity is calculated based on the reduced pressure, whereas, in the second stage, at fractions solid greater than the liquid encapsulation point, the fraction porosity is calculated based on the volume of liquid trapped within the continuous solid network, which is estimated using a correlation based on the Niyama parameter, The porosity model uses thermal data calculated using the commercial finite element package ABAQUSTM. The model has been applied to examine the evolution of porosity in a series of experimental samples cast using unmodified A356 in which the initial hydrogen content was varied from 0,048 to 0.137 [cc/100g], A comparison between the model predictions and the experimental measurements indicates good agreement in terms of the variation in porosity with distance from the chill and the variation resulting from initial hydrogen content.

Jan 1, 2005

By A. Paulin, J. Roth, S. Spaic

This experiment was carried out to see whether copper-iron ingots from Late Bronze Age hoards could have been produced by smelting ferruginous copper ores. Since ferruginous copper-ores are chalcopyritic, chalcopyritic concentrate from a present day copper mine was dead roasted in our experiment in lieu of a rich chalcopyritic ore. Charcoal was used as a reducing agent in the reduction of calcine (i.e., a product of dead-roasting), and quartz sand was used as a flux. Two separate metallic solutions, a copper-base and an iron-base alloy, were obtained as a result of two factors: the presence of carbon and the miscibility gap in the Cu-Fe-C system. The metallic melts appeared in a form of bigger or smaller droplets, enclosed by a molten slag which, during the cooling, solidified into metallic beads. The presence of both metals was noticed in the majority of the examined beads. It was therefore concluded that calcine consisted of an intimate mixture of oxides of both metals which were simultaneously reduced during the reduction process. Due to the miscibility gap in the Cu-Fe-C system, separate iron and copper regions were formed in the beads. In both regions, sulphide inclusions were found. The formed molten copper and molten iron solution were found to be saturated solutions. The metallographic analysis revealed the precipitation of iron out of copper and that of copper out of iron during the cooling and solidification of melts. The formed slag contained little iron and no copper oxide.

Jan 1, 2001

By V. K. Karra

"A simplistic algorithm jar simulating the rod or ball mill Bond grindability test applied to ores and minerals is presented. A performance comparison between the present algorithm and a previously published algorithm by Kapurot, modified in this work jar a fair evaluation, is also given. A worked example is furnished jar leading the reader through the various calculations.IntroductionThe Bond grindability test is widely used for the prediction of the power requirement of an industrial grinding mill. The procedures for conducting this test in either a ball or a rod mill are available(1). In the case of a ball mill, batch grind abilities have been correlated to Bond grindabilities to help monitor day-today variations in ore grindability for the purpose of plant control( 2,3). Of special interest is the algorithm presented by Kapur(3) for the simulation of the Bond test. In practice, the test lasts from 6 to 14 cycles (4 to 10 hours). With this algorithm, one can predict the Bond grind ability using information available from only the first two cycles.Sometimes the prepared feed for the grindability test contains too much fines compared to the total product desired at the mesh of grind under consideration. In such a case, the operator separates the fines from the test feed and adds to the remaining coarse fraction an equal amount of fresh feed. This combined feed then forms the feed to the first cycle of the test. In the present work, Kapur's algorithm is modified to include this special case. A new and relatively simpler algorithm is also presented. Statistical equations relating work index to pertinent variables are also given."

Jan 1, 1981

By G. Cailletaud, I. Guillot, D. Larouche, R. Martinez, D. Massinon

The precipitation of Al2Cu particles in a 319 T7 aluminum alloy has been modeled. A theoretical approach enables the concomitant computation of nucleation, growth and coarsening, based on an implicit scheme using the finite differences. The equation of continuity is discretized in time and space in order to obtain a matricial form. The inversion of a tridiagonal matrix allows us to determine the evolution of the size distribution of Al2Cu particles at t + dt. The fluxes of solute in-between the boundaries, as well as the ones at the boundaries, are computed in order to respect the conservation of the mass of the system. The main results of the model are compared to TEM measurements. Simulations provide quantitative features on the impact of the cooling rate on the size distribution of Al2Cu particles in good agreement with the TEM measurements. This metallurgical model is integrated into FEA software in order to perform mechanical computations. This kind of multiscale approach allows new perspectives to be investigated in the process of designing cylinder heads. It enables a more precise prediction of the microstructure, its evolution as a function of continuous cooling rates and its impact on the integrity of the structure.

Jan 1, 2015

By M. Leahy

"Very little is known about the large scale fluid dynamics and associated distribution of copper in an operating electrowinning cell, yet they will have a major influence on mass transfer and plating quality. The CFD model in this work is used to simulate an entire EW cell with 60 cathodes and 61 anodes, or 121 anode–cathode pairs, elucidating for the first time the three-dimensional (3D) flow and copper distribution in an industrial cell. Two methods for the distribution of electrolyte are modelled:1. Downcomer method: electrolyte is fed by a downcomer at one end of the cell, overflowing at the opposite end.2. Manifold method: a horizontal manifold pipe runs the whole length of the cell and feeds electrolyte via small holes in the top of the manifold pipe.The recirculation that develops within each anode-cathode pair, driven by oxygen bubble generation on the anode, is similar to that seen previously in two-dimensional models of single anode–cathode gaps. However a more complex 3D flow recirculation is established, which involves flow of electrolyte down the side gaps (being a path of low resistance for return flow) as well as the usual return flow down the cathode side of each pair gap. The bubble-driven flow is not influenced by the mode of electrolyte distribution.The electrolyte flow due to the manifold and downcomer is somewhat secondary to the bubble driven flow. In the case of the downcomer distribution mode, the high injection velocity causes a very turbulent flow in the first 1–2 m down the cell from the downcomer, with several large vortices developing. This may lead to some sludge particles being entrained into the bulk of the cell.In the manifold pipe case, the jet from each hole is dissipated very quickly, within the first 10–20 cm. The jets are directed into the downward flowing zone of the bubble-driven recirculation, which leads to unstable and periodic behaviour on a large spatial scale.In both the manifold and downcomer cases, there is a marked two-zone vertical stratification in copper concentration."

Jan 1, 2016

By Daniel Lachapelle, Nuri Hmidi, Turgut Yalcin

"Simulation can serve as a convenient tool in studying the behaviour and performance of grinding circuits by facilitating the evaluation of various scenarios and identification of optimum operating conditions. This technique was applied to the St Andrew Goldfields Ltd.’s Stock Mine Mill which is a 1300 tpd gold milling facility, offering custom milling services as well as processing the Company’s own ores. Lack of adequate instrumentation in the mill poses a challenge in attaining optimum performance especially with changing ore types and characteristics. The grinding process is monitored essentially by manual measurement and adjustment of pulp densities at various streams. A simulation program was designed to assist in the effective implementation of this mode of grinding control. Product sizes from both the primary and secondary grinding circuits were correlated empirically to relevant process variables using a database formed from the results of past sampling campaigns. The simulator was created in Microsoft Excel whose data analysis and optimization tools coupled with its Visual Basic Programming capabilities were found to provide an excellent environment for the development of a cost-effective, efficient and user-friendly simulation program.INTRODUCTIONGrinding is often a very costly unit process in milling operations, mainly due to the excessive energy consumption associated with it. For example, for a Canadian copper-zinc flotation mill, grinding was listed as being the most costly item taking up 30.4% of the total milling expenses, followed by the flotation cost at 2 1 .O% (Kidd Creek Mines Ltd., 1982). A survey on 45 copper flotation mills around the world showed the average grinding cost to be 34.5% of the total milling cost (Weiss, 1985).Overgrinding aggravates the cost issue, while insufficient grinding either causes loss of valuable minerals to tails or results in low-grade concentrates. Therefore, it is essential that grinding circuits be carefully controlled and monitored. To this end, a great deal of effort has been devoted over the years to the modelling and simulation of grinding systems in order to assist in the efficient running of these processes."

Jan 1, 2001

By D. J. Xue

Four kinds of coal-rock combination were subjected to three kinds of stress waves in the SHPB numerical simulation. The wave propagation and the changes of the strain energy in the coal-rock combination during the dynamic impact process were recorded as well as the contact force. The dynamic response law of coal-rock combination was obtained. It was found that the coal had better reflectivity than the rock because of coal with larger impedance. In contrast the rock had better transmissivity. As the crest value of the incident wave increased, the increment in the crest value of the transmitted wave weakened in the coal-coal group, coal-rock group and rock-coal group, in contrast, the increment in the rock-rock group increased.

Aug 1, 2013

By Rodrigo Toro, Mario Delisle, Claudio Zamora

"The mining market is researching innovative methods to train the workforce for mining which is normally extremely difficult to get. Thus, the dynamic simulation-based technologies become an essential pillar to educate and train the inexperienced staff at the pace required by this industry. Even if Operator Training Simulator (OTS) systems are commonly used in most of industries, knowledge transmitted to operators are unfortunately not ""capitalized"" in general. The OTS systems are usually delivered as a single hardware and software platform and very little as a full service long-term.In this article, an integrated solution to increase the efficiency of the operators is proposed. This solution is based on the combination of dynamic simulation, processes knowledge, virtual reality and the knowledge capitalization through the creation of simulation scenarios and e-learning. The Codelco Ministro Hales plant simulation project for a copper concentrator plant is presented as a real life example.IntroductionDynamic and real-time process simulation have proven to be a must in the development of greenfield projects, providing mechanisms to design and test controls design, interlocks, start-up, shut down sequences and operator training, among others (see (McMillan, 2006) for further details). Early adopters of this technology were utility power plants; in the petrochemical industry have become a standard, and in the mining industry the use of dynamic simulations is growing, especially in new projects and training of operations personnel for the adoption of best practices and new technologies, see (Nikkhah & Anderson, 2001) and (Toro, Ortiz, & Yutronic, 2012).This paper outlines a solution that utilizes dynamic simulations as the base of an integrated platform for operational effectiveness, which takes into account the current scenario of new mining projects and operations, where high turn over rates and needs of specialized workforce have given a special value to this kind of technologies."

Jan 1, 2015