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By Sanjay Chaudhuri, V. K. Kalyani, Pradeep Kumar Singh, T. Gouri Charan

"Indian coal industry is the world's third largest in terms of production and fourth largest in terms of proven coal resources. Indian coal deposits are generally of high ash content varying from 24 to 50%. The coking coal reserves of India constitute about 12% of the total coal inventory, and the coals are washed in washeries, before being used for metallurgical purposes. The processes used for washing coking coal is Jigs, Heavy medium bath and Cyclones for the sizes upto 0.5mm, while the coal fines are washed in spirals and conventional flotation cells. Extensive studies were carried out for understanding the performance of an operating conventional flotation plant. The performance studies revealed that appreciable quantity of clean coal is being lost in the tailings due to varied reasons and the required quantity and quality was not achieved. In this study, laboratory Flotation experiments were carried out to examine the cleaning characteristics of the said tailing and to determine the effective process parameters for recovery of clean coal at desired ash level ( 16-17%). Response Surface Methodology was applied to investigate the operating conditions of the Froth Flotation for modeling and optimization. Primary study reflects that there is a possibility to recover clean coal at 16-17% ash level with a yield of about 60-70% from that Flotation tailing of feed ash about 28%.INTRODUCTIONMost of the Indian coking coals are difficult in cleaning characteristics and high ash content due to its drift origin and its age of formation for more than 225 million years. Indian coking coal reserve is limited about 12% of total coal reserve. The minerals are homogeneously mixed with the coal macerals. The open cast mining practice and mechanized mining methods are being adopted to meet the increasing demands of coals resulting in generation of more coal fines and subsequently the quality is deteriorated. Indian good quality coking coal reserves of higher seams are fast depleting and hence coking coals of difficult cleaning characteristics of lower seams (LVC) are being now explored. Due to increased mechanization of coal mines to cope up the increased demand and followed by size reduction of lower seam coals in search of better liberation , the coal fines are increasing by leaps and bounds. The processes used for washing coking coal is Jigs, Heavy medium bath and Cyclones for the sizes upto 0.5mm, while the coal fines are washed in spirals and conventional flotation cells."

Jan 1, 2018

By A. G. Raraz

Reactive metal electrorefining presents a number of problems that pose obstacles to commercial operation. Cerium has been chosen as the surrogate for certain reactive metals because of its thermodynamic and electrochemical characteristics. A comparative review of the properties for cerium and plutonium has been presented to justify the choice of cerium as the surrogate metal for studying electrorefining. This review has addressed the electrochemical, thermodynamic, and kinetic parameters of molten salt electrorefining of cerium metal to provide an insight to this extremely important process. The cell components and configuration, current efficiency of the process, purity of the cathodically deposited metal and the power requirement of the system are evaluated for a molten CaCl2-MgCl2 salt electrolyte using a molten, stirred impure anode. Crucible designs, salt electrolyte, cell temperature and electrode materials are also evaluated. Selection of the salt electrolyte and the cell temperature have been suggested from this study.

Jan 1, 1992

By L. Ibagos S., T. Balberyszski

The volumetric flow rate and the initial concentration of the copper sulfate solution influence the rate of reaction and, hence, the precipitation efficiency in a continuous launder cementation system. Using a model of such a system it was found that the precipitation efficiency is related to the two process parameters by the approximate expression [ log [1-n] = -[0.072 co 2.91 e – 0.511c o Q 1.15 ] N Q] where c is the initial concentration, Q, is the volumetric flow rate and N is the number of launders in the system. This expression agrees with an equation developed for the rate of the cementation process if it is assumed that the exponential factor represents the change in the surface area with concentration and the exponents 2.91-and 1.15 relate the hydrodynamic conditions and the surface concentration to co and Q. The experimental results are used to determine the values of a Precipitation Coefficient for any volumentric flow rate and initial concentration of solution. Knowing the Precipitation Coefficient, the total volume of launders that will result in a given precipitation efficiency can be calculated. It is established that maximum precipitation efficiencies are obtained for initial concentrations between 6.0 and 7.0 gpl and volumetric flow rates of approximately 350 m3 /hr Good agreement between calculated and actual launder volumes is obtained for a number of industrial operations for which a comparison is made.

Jan 1, 1973

By M. Medraj, M. A. Arafin, D. P. Turner, P. Bocher

In this study, the kinetics of isothermal solidification during TLP bonding of Inconel 625 and 718 superalloys with nickel based multi-component filler alloy BNi-2 have been studied through a combination of direct experimentation and mathematical modeling in order to determine the effect of process variables and, thus, to optimize the process. The predicted isothermal solidification completion times from the boron diffusion model and migrating solid/liquid interface model were in good agreement with the experimentally determined values and, they were found to be significantly less than those of other nickel superalloys with different nickel based filler alloys. Further, significant reduction of holding time was observed with increasing bonding temperature and with decreasing joint gap. No significant grain growth in the base metals has been observed in the temperature range being investigated (1325 - 1394K).

Jan 1, 2006

By Barry J. Hansen, Ruston A. Ford

Production of mine backfill from the tailings produced in a proposed Crandon concentrator is described. A process has been developed capable of producing suitable fill for the mining method selected for the Crandon orebody. It maximizes the placement of pyrite underground as fill and segregates tailings into pyrite and nonsulfide fractions. To determine the suitability and engineering characteristics of the backfill product for use underground, laboratory and physical stope simulation model testing was conducted. The results of the testing and the application of those results to the design of the backfill system ultimately affecting mine geometry and subsequent mine production will be presented.

Jan 1, 1981

By Anthony Busigin, Stephen Pogorski, Colin R. Phillips

The precision of radon daughter measurement techniques is a complicated function of uncertainties arising from concentration and flowrate fluctuations during sampling, counting statistics and many other factors. Optimization of a measurement technique requires that all these uncertainties - not just counting statistics - be considered. In this work, the optimization procedure of Busigin and Phillips (1980) is tested against Monte Carlo experiments for the case of the modified Tsivoglou method.

Jan 1, 1981

By Grant Wallace, Rod James, Larry Twidwell, Ed Rosenberg, Courtney Young, Sean Dudley, Hsing-Hsin Huang, William Gleason, Jerome Downey

The use of applied chemistry in the production and optimization of leach solutions from Rare Earth Element (REE) ores and concentrates is being investigated. Ore and concentrate samples were characterized using scanning electron microscopy/mineral liberation analysis (SEM/MLA), X-ray diffraction (XRD), and Atomic emission inductively-coupled plasma spectroscopy (ICPAES). Multiple leach tests were performed to analyze the effects of temperature, residence time, and reagent concentration on the leaching of REEs. Analysis of leach solutions was carried out using ICP-AES. Modeling and statistical analysis of extraction behavior was carried out using DesignExpert 9. Modeling data for cerium extraction indicates that extraction is greatly influenced by temperature and reagent concentration, while leaching time plays a much less important role. Experimental design techniques are being utilized to optimize REE recovery. Results, conclusions, and directions for future studies will also be discussed.

Jan 1, 2015

By A. J. Rigby

Anode vessels are often relined with refractory every one to two years and a typical reline time can take between 16-20 days. Modem refractory designs using dense, corrosion resistant brick applied directly to the vessel shell in the high wear areas around and above the tuyeres and at the slagline can yield a lining life of up to 4-5 years before a complete reline is necessary. Installation methods using brick delivery on roller conveyors through an endwall access port and complete anchoring of the brick to allow for lining self-support can take days off the installation time. It is possible, therefore, to reduce the refractory relining period by 50% and increase lining life by 100% compared to typical anode repair schemes. Cu2007

Jan 1, 2007

By J. A. Herbst, T. I. Martinovic, Y. C. Lo

This study was concerned with the application of a computer simulation methodology to optimize the performance of mills grinding iron ore concentrate prior to pelletizing. The methodology involves batch and plant testing, modeling and computer simulation. The analysis of grinding performance was carried out and capacity increases were predicted in the context of detailed population balance models developed for the plant ball mills. Model developnent and plant confirmation were performed using data obtained in a series of batch tests and three plant tests. From experimental data and computer simulation it was found that ball size, percent solids and classification all had a significant effect on mill throughput. Based on the findings of this study, a 12-152 increase in capacity was predicted to be available by a proper combination of ball size charge and optimum percent solids. These predictions have been confirmed by plant tests in which the recommended operating changes have been made.

Jan 1, 1990

By A. Vishwakarma, V. Himanshu, K. Dey

Underground mining is the most feasible method after extinction of shallow depth ore deposits. Longhole stoping method is the most technically advanced method for the faster excavation. In this method, the holes are drilled in the form of ring pattern and explosives are used for the rock breakage. During blasting, the explosive energy sometimes also breaks the non-ore material. The non-ore material gets included in the extracted ore and enhances the ore dilution. Few uncontrollable factors which affects the ore dilution are ore body characteristics, rock quality, insitu stress condition etc. Apart from uncontrollable factors, explosive energy and blast design also plays an immense role in ore dilution. In the blasting practice, the purpose is to effectively utilise the explosive energy for rock breakage. The optimum delay is required so that the blast holes attain adequate free face before the blasting. This paper deals with the optimisation of blast design parameters to reduce ore dilution in underground hard rock mining having narrow vein. The study was carried out using numerical simulation. The explicit dynamics based modeller of Ansys was used for this purpose. The parametric variations in the models were done to optimise the parameters. The burden has been optimised first by varying the width of the narrow vein. The blasts of a ring consisting of single hole were conducted in the model by varying the width of the narrow vein. The damage contour under different parametric variations were analysed. The experimental trial has been also carried out at Zawar Group of Mine, Rajasthan, India. The optimum parameter was decided based on the result of experimental trial and numerical simulation model. The output of the model shows that optimum burden for 3.5 m narrow vein width is 1.12 m and for 1.0 m, it is 1.54 m. This shows that the optimised burden is higher in the vein having lesser width as compared to the greater width. The presence of joints/changed media/interface (between the sidewall and narrow vein) is the major reason behind this. The wave gets reflected back very fast on coming in contact with joints in a 1.0 m narrow vein as compared to a 4.0 m narrow vein. This will quickly convert the compressive wave into tensile wave giving rise to tensile slabbing. Hence proper utilisation of explosive energy will take place for the breakage of rock mass when the width of the narrow vein is smaller. The burden obtained from the experimental trial and numerical simulation models is less than 2.0 %. Hence the numerical simulation based approach can be used for the assessment of the optimum burden for ring blasting in narrow vein under different geomining conditions. This helped in reducing ore dilution and maximization of ore recovery. In the future, empirical relationships may be developed by considering different geological discontinuity, the strength of the rock mass and explosive parameters.

Jan 1, 2024

By Antônio Aldenor Pinheiro Neto, Matheus de Lima Vieira

In mid-2015 the steel industry faced a strong crisis due to the weak performance of the Brazilian economy and the persistent entry of Chinese steel into Brazilian territory. This situation demanded that Brazilian steelmakers seek to develop products to meet new export markets. within the volume of exports possible are the rebars, where its applications are in the construction industry. One of the largest importers is Peru which has a large percentage of this export volume. This market demands as a priority requirement the surface quality of blue condition (low oxidation index) and mechanical properties normative.in order to meet the items required by the customer at a competitive cost, a vanadium microalloyed steel was applied to the hot rolling process without heat treatment after the last rolling pass. Where the great challenge was to achieve a high level of stretching without compromising the minimum limits of tensile strength. Assuming that the steel used is the correct one interventions were made on rolling parameters such as set-point temperature, residence time of pieces in the furnace, linear mass and rolling speed. All the changes made were based on statistical tools and practical tests. Finally, with the execution of actions generated from the statistical analyzes and tests it was possible to reduce process losses by 96%.

Oct 1, 2019

By T. Laxmi

This paper details the optimization of rougher Wet High Intensity Magnetic Separator (WHIMS) using response surface methodology. The optimization is in parametric form and takes account of the major operating variables in WHIMS operation such as current in ampere and grid gap, in inch. The objective is to recover ilmenite mineral from red sediment deposits of Srikakulam, India by optimizing the rougher WHIMS. We predict mineral recoveries as a function of current and grid gap. Combination of these predictions with assay data provides predictions of mineral grades and recoveries. The optimized response was validated against data derived from laboratory-scale rougher WHIMS test work, comprising (i) mineral grade, (ii) mineral recovery, and (iii) separation efficiency of the process. We observed close match between the experimental and the predicted data over most of the operational range. This paper describes how the optimization was carried out using the response surface methodology along with MATLAB. The response surface was used to closely investigate the separation of ilmenite mineral by varying ampere and grid gap. The results show that under optimum conditions, such as 3.5 amp current (0.53 Tesla) and 2 inch grid gap, the mineral grade could reach, as high as 87.9% in the concentrate with 74.3 % recovery and 74.4% yield. Keywords: red sediment, wet high intensity magnetic separator, optimization, ilmenite, placer heavy minerals

Sep 1, 2012

By G. Couture, J. -F. Dubé, F. Letarte-Lavoie

"The Xstrata Nickel Raglan concentrator, located in Quebec’s Nunavik region, has been in operation since 1997. Originally designed to process 800,000 tonnes per year of high-grade nickel ore, the plant’s current capacity is 1.3 million tonnes per year due to various optimization projects. In 2011 and 2012, the Metallurgical group, with assistance from BBA, updated and optimized the variables affecting SAG throughput in order to optimize process stability while maintaining maximum plant throughput. This project consisted of reviewing the control strategy and completely updating the pre-existing Fuzzy Logic controller. This paper describes the successful update of the controller including a complete revision of control rules, a new process control strategy and the integration of new process variables, most notably mill rotational speed. It will also show how this new approach has provided a simple and robust way of delivering both an increase in throughput while reducing process variability.INTRODUCTIONThe Xstrata Nickel Raglan Mine concentrator is located in Northern Quebec along the 62th parallel. It has been in operation since 1997 and was originally designed to treat 800,000 tonnes of ore annually. The Raglan Agreement held with the Makivik Corporation and the Inuit communities limits the annual tonnage of ore that can be processed at 1.32 million tonnes.The ore is processed in a 24 foot variable speed, semi-autogenous grinding mill (SAG). The conversion from Autogenous Grinding (AG) to SAG was completed in 2006. Before the ore is processed by the SAG, its size is analyzed by a Wipfrag camera that provides a granulometry estimate. A cone crusher reduces the SAG’s discharge screen’s oversize material. A 14 foot diameter ball mill ensures final grinding before the flotation stage.Many control strategies were used at the SAG over the past few years. Fuzzy Logic was first used in 2007 in order to control tonnage feed to the SAG. This first version only measured the value of the variables without taking into account their rate of change. Revisions were made over the course of the last few years to improve controller performance. Other variables were added such as slurry density and crusher Closed Side Setting (CSS). The previous revision of the Fuzzy Logic was done in 2009 with a review of the rules only."

Jan 1, 2013

By T. Uysal

Various morphological parameters that affect the flotation recovery of sphalerite were modelled and optimized using the response surface method (RSM). The effects of roughness value, shape factor, and collector concentration were investigated using the central composite full design method. The results were evaluated by analysis of variance. The optimum roughening time was found to be 25minutes, the optimum roughness value was 2.9071 μm, and the optimum collector concentrationwas 0.001 M. Using these values, a flotation recovery of 98.01% was obtained. Similarly, in shapefactor studies, the optimum grinding time was 15 seconds, the optimum roundness value 0.7421, and the optimum collector concentration 0.0009 M, which resulted in a flotation recovery of 94.30%. The average error between the optimization results and the experimental results was estimated to be less than 6%, and the R2 values were greater than 90%. The study shows that RSM can be effectively applied in finding the economic optimum condition for obtaining maximum flotation recovery with minimum reagent consumption.

Sep 6, 2023

By J. Pelders, F. Magweregwede, S. M. Rupprecht

Increased depths of conventional gold and platinum mines, longer travelling times as working places move further from the shaft, and ancillary activities taking place in the mining cycle reduce the useable time spent at them workface. Current shift lengths of 8 hours 20 minutes may no longer be adequate ton complete required mining activities.The impact of mineworker commuting times on shift work is also not well understood. The aim of this research was to draft a framework to optimize shift cycles in order to maximize productivity, health, safety, and wellness in the South African mining sector. The framework was informed by a review of the literature, case studies at a local gold mine and platinum mine, and a workshop with industry experts. The findings indicate potential advantages of extended shift lengths and continuous operations, such as improved productivity, asset utilization, and employee morale. However, concerns included fatigue and the associated safety hazards, particularly when working longer shifts, night shifts, and numerous consecutive shifts. Job demands, personal factors, and commuting times are further considerations when scheduling shifts. The ideal shift system for the mining sector should holistically consider and balance operational requirements, health and safety, and employees’ and their families’ requirements, and suit the unique needs of each operation. Changes in shift cycles will require a structured change management process, which involves all stakeholders, and could help to enhance the viability of the South African mining sector.

Aug 1, 2021

By S. Frimpong

Shovel excavation constitutes a significant component of production costs in any surface mining operation. This makes shovel loading an important cost center that needs to be improved to lower production costs. Optimization of tool design will improve energy efficiency in earthmoving operations. However, modeling the soil-tool interaction is a complex process due to the fact that forces for excavating particulate material are functions of many variables. The magnitude of this resisting force depends not only on the type of soil but on the size, shape and orientation of the cutting element. Moreover, part of this complexity is attributed to the fact that the behavior of the material during excavation is not yet well understood. For the past five decades, researchers have mostly used the passive earth pressure theory to study the soil failure patterns around a cutting tool and to develop force prediction models for design optimization with some success. Although the force models developed from the passive pressure theory have been successful to some extent, they can hardly be extended to a general case because of the underlying assumptions and simplification of tool shapes. This paper aims at reviewing some of the existing empirical and analytical methods of cutting and excavation tool modeling with a focus on their merits and limitations. The paper also explores the use of numerical methods, specifically the discrete element method, for dealing with the unresolved aspects of soil dynamics in excavation.

Jan 1, 2011

By S. G. Ercelebi

In surface mining operations, truck haulage is the largest item in the operating costs, constituting 50 to 60% of the total. In order to reduce this cost, it is necessary to allocate and dispatch the trucks efficiently. This paper describes shovel and truck operation models and optimization approaches for the allocation and dispatching of trucks under various operating conditions. Closed queuing network theory is employed for the allocation of trucks and linear programming for the purpose of truck dispatching to shovels. A case study was applied for the Orhaneli Open Pit Coal Mine in Turkey. This approach would provide the capability of estimating system performance measures (mine throughput, mean number of trucks, mean waiting time, etc.) for planning purposes when the truck fleet is composed of identical trucks. A computational study is presented to show how choosing the optimum number of trucks and optimum dispatching policy affect the cost of moving material in a truck-shovel system. Keywords: Open pit mine, equipment selection, dispatching, linear programming, closed queuing network theory

Jan 1, 2009

By D. Komljenovic

This paper presents the use of queuing theory in truck fleet sizing in open pit mining operations. In the first part, a methodology is developed by which an optimal ratio between the size of shovels and trucks may be determined. The second part gives the fundamentals of the queuing theory and its application in analyzing shovel and trucks. The stochastic character of involved times (loading, truck cycle, etc.) is taken into consideration. Using the above theory, the optimal truck fleet size in actual conditions may be estimated. Minimal operating cost of the working system (shovels-trucks) represents the basic requirement of the analyzed process. The methodology was validated on Caterpillar front-shovel ? truck combinations.

Sep 1, 2004

By P. R. Segopolo

"The purpose of the project is to convert current shuttle car utilization on an underground coal mine to best practice by focusing on change-out points and tramming routes, which have a major influence on shuttle car away times. Time studies were an integral part of the project as these enabled the determination of shuttle car away times. An indirect proportional relationship between shuttle car away times and productivity is established. Through the time studies, it is deduced that a third shuttle car will make an insignificant contribution to production when there is only one split open. During this time, maintenance on the third car can be optimized. In order to satisfy the mine’s key performance indicator of keeping shuttle car away times less than 75 seconds, a belt extension must be scheduled after the third split is open. It is established that at any given time, a minimum of two shuttle cars should be used. When cutting on the left-hand-side of the belt road with only two shuttle cars available, the centre and left (left of the feeder breaker) shuttle cars should be used for coal hauling. When cutting on the right-hand-side, the centre and the right-hand-side cars should be used. If only one shuttle car is available, the centre car is the most efficient to use. Alternative anchoring configurations can be employed so as to enable cars (left or right, especially) to reach the opposite extremities of the panel and hence minimize cable length restrictions. Paper written on project work carried out in partial fulfilment of BSc. Eng. (MiningEngineering)"

Jan 1, 2015

By M. Saba

In cyanide leaching procedure, achieving an acceptable efficiency for silver and gold is very time-consuming, thus, enough studies have not been performed for optimization and modeling of this process. The kinetics of cyanide leaching includes two steps: first step comprises a sharp slope while the other has a slight increasing trend. In the present study, in order to reduce the time and cost, the cyanide leaching process of a sulfide silver/gold ore was optimized in the first period. The applied parameters and their ranges are: temperature 20-40 (°C); time 1-8 (hrs); cyanide concentration 1-2 (mole cyanide / mole Cu); the percentage of solid to liquid 1-2 (%) and pH 10-12. For design of experiments fractional factorial 2(5-1) was used. Also four center points were applied to increase the accuracy of the model. In addition, by analysis of variance (ANOVA) the most effective parameters were identified and the optimized condition was determined. A regression model was proposed to describe the effects of independent variables and their interacting role on silver recovery. Results showed that the model was linear for silver and nonlinear for gold. In the gold recovery process, the two important parameters are time and pH with the former being more effective. Due to the existence of cyanide ions in the medium, temperature and cyanide concentration have less influence in the gold recovery process. Solid to liquid ratio, in addition, comprises a slight negative impact on the procedure. This emphasizes the different kinetics of silver/ gold cyanide leaching. Finally, using the optimum condition the amount of silver and gold obtained were 61% and 67% in 8 hours, respectively. While in general conditions, the results were 37% and 54% in 24 hours, respectively. Keywords: cyanide leaching, refractory gold/silver ore, modeling, optimization

Sep 1, 2012