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By S. Banisi, A. Ghasemi, S. Zare, F. Ghorbani, E. Nematollahi

"Comminution is the most energy intensive operation which constitutes the major portion of operating and capital costs of the mineral processing plants. Working at the maximum operating capacity of comminution equipment plays a significant role in the efficiency of the circuit. Appropriate design of cone crusher feed box could result in the choked crushing which is known as a vital factor in achieving target performance. In this research, the non-uniform cone crusher feeding at the Sarcheshmeh copper complex was studied and appropriate measures were taken to solve the problem. The problem resulted in non-uniform and high wear rate of crusher liners and high fluctuations of power draw. In recent decades, the discrete element method (DEM) has been applied successfully to study the effect of different factors on the behavior of particles flow. In this work, various designs for feed box were tested using an in-house developed DEM software called KMPCDEM©. The best feed box design obtained from the simulations was selected, constructed and installed in of the cone crushers. The new feed box design resulted in more uniform feed distribution on the distributor plate of crusher indicated by a reduction of the standard deviation of power draw measurements from 13 to 3 kWh. The better control of the crusher, 49% increase in the crusher throughput and finer and narrower product size distribution were the main outcomes of the installation of the new feed box. Furthermore, the wear rate on mantle and liners of crusher not only decreased but it also became uniform.INTRODUCTION Comminution is the most energy intensive operation which constitutes the major portion of operating and capital costs of the mineral processing plants. Reaching the maximum operating capacity in comminution equipment is a key sign of approaching the nominal productivity of the process. Due to the effect of crusher efficiency on the downstream circuit performance, optimization of the crushing circuits has received considerable attention (Herbst, & Potapov, 2004; Quist, & Evertsson, 2010; Li, Huiqi, McDowell, Glenn R, Lowndes and Ian, 2014; Cleary, Sinnott, Morrison, Cummins, & Delaney, 2017). Improving the performance of crushing circuits not only decreases the capital and operating costs but also increases the efficiency of downstream grinding circuits (Jacobson, Janssen, & Urbinatti, 2010). In cone crushers particles can be subjected to two different modes of compressive breakage; single particle breakage (free feeding) and inter-particle breakage (choked feeding). The maximum efficiency of the cone crusher directly depends on the type of feeding arrangement (Operation Manual, 1977). An appropriate feeding must lead to choked feeding the cone crusher. If the rate and method of feeding the crushers are correctly be executed, the maximum efficiency of the crushers could be available (Jacobson et al., 2010)."

Jan 1, 2018

By Susanna A. C. Stadler, Chris Aldrich, Jacques J. Eksteen

"Slag foaming occurs in several pyrometallurgical processes. These processes include steelmaking in basic oxygen steelmaking furnaces and electric arc furnaces as well as various non-ferrous operations like sulphide smelting/converting and base metal slag cleaning. Although slag foaming in steelmaking processes has been extensively researched, little attention has been given to slag foaming in non-ferrous operations. Slag foaming phenomena are complex because often the system consists of three or more phases. With this in mind, factors previously identified as influencing slag foaming were investigated. These include the slag basicity, physical properties of the slag, namely viscosity, surface tension and density, the formation of particles due to undercooling of the slag and the FexO concentration in the slag.Slag foaming was investigated in a vertical tube furnace. The different slags were contained in alumina crucibles and bubbling argon gas through the molten slag induced foaming. The foam height was measured by using stainless steel probes and a voltmeter. The conductivity of the slags made it possible to measure the foam height from the position of the probes when the electrical circuit was completed. Slags were foamed at different temperatures to investigate the effect of solid precipitates.The effect of increasing FexO concentration was found to decrease the foam index due to lower viscosities, but higher surface tension depression appears to have led to increased foam index values at high FexO concentrations."

Jan 1, 2003

By Rodolfo Silva, Antonio Peres, Afonso Martins, Gilberto Ramalho, Mario Cabello

The consumption of aggregates in civil construction has increased considerably in Brazil for the last years. The extraction of sand and gravel generates significant environmental impacts. As the quarries and sand deposits are getting exhausted near the big cities, the price of aggregates is increasing. Meanwhile, the extraction of quartzite (dimensional stone) in the state of Minas Gerais has been done mostly in small quarries, with very low recovery, generating approximately six million tons of wastes a year, which causes pollution, increases final prices of products, decreases the life time of quarries and ends up in the closure of enterprises. The government agencies and the quarries’ owners understand that only by finding applications to wastes there will be development to the sector. The aim of this investigation was to study the application to the quartzite wastes as aggregate in the civil construction. Samples of quartzite wastes collected in a quarry were characterized by petrographic analyses. Laboratory tests of crushing and grinding were done to analyze the viability of reducing the size of coarse material to a finer one to be used as raw material in industrialized mortars and concrete pre-molded components.

Jan 1, 2014

By K. D’Elia, L. D. Ogrel, O. A. Malyshev, T. I. Yushina, I. M. Petrov

"The purpose of this research is to develop enhancements in the mineral processing by flotation methods of nonferrous ores. Currently, 180-190 million tons of ore are processed by flotation in Russia. The annual processing volume of copper-nickel and copper-zinc ores exceeds 20 million tons. In the total volume of processed ores by flotation, non-ferrous ores account for roughly 35% and ores of precious metals for another 15%. The total demand of flotation reagents in Russia in 2016 was estimated at 170,000 tons. Sulfur-based collectors used in the flotation of non-ferrous sulfide ores (typically, xanthates) do not always offer sufficiently high recovery of valuable components.It has been found that reagents like DMIPEC and DK-80 improve the recovery of metals into concentrates. To identify the reasons of that higher recovery, quantum chemical calculations of the mechanism and interaction forces of DMIPEC with non-ferrous sulfides were undertaken by determining the stabilization energy of the resulting chemical complexes. It has been shown that, in the interaction of DMIPEC and DK-80 with the surfaces of sulfide minerals, ethylene and acetylene bonds act as the reaction centers, and the formation of molecular p-complexes is the result of metal-cation interactions with the surface and the flotation reagents.In the flotation of non-ferrous ores, DMIPEC and DK-80 act as selective supplementary collectors with foaming properties, and at a flow rate of 3-35 g/ton, they reduce the flotation time, and increase copper recovery by up to 3.5%, zinc recovery by up to 12%, gold recovery by up to 8-10%, allowing to increase the recovery of valuable components by 1.5-12.0%, basically this kind of reagents nearly double the flotation rate, improve the grade of the concentrate, improve the stability of the flotation process parameters, and reduce the environmental impact of flotation plants."

Jan 1, 2018

There are some problems in the beneficiation of fine-grained oxidized iron mineral such as high cost, severe sliming, poor results and low recovery due to the fine disseminated size of the mineral. Taking several representative types of finely-disseminated oxidized iron minerals as examples, the author analyzed the main difficulties in the beneficiation of such kind of ores and discussed the existing problems in grinding-classification, technological process, flotation reagents and separation equipments and the resolvents of these problems.

Jan 1, 2014

By Yang Xiao, Zhang Yimin, Bao Shenxu, Liu Chun

Stone coal is a unique vanadium-bearing resource in China. Many techniques, such as salt roasting-water leaching, blank roasting-acid leaching, direct acid leaching etc. have been developed for vanadium extraction from stone coal. The vanadium leaching rate can reach 74.9% for stone coal from Jiangxi, but only about 27% of vanadium is leached for Hubei ore by applying salt roasting-water leaching technique. This paper investigats the vanadium occurrence in stone coal by microscope observation and electron probe, and compares the minerals components of stone coal from Jiangxi and Hubei. Although most vanadium exist as an isomorphism by replacing Al(III) from dioctahedral structure in mica group minerals in stone coal from two regions, the free vanadium is remarkably abundant in Jiangxi stone coal than in Hubei stone coal, which results the fact that vandium is relatively readily extracted from former. Moreover, the content of calcite in Hubei stone coal is much higher than that in Jiangxi stone coal. Calcium can react with V2O5 to form water insoluble calcium vanadates during roasting and this may be the reasone why the water leaching rate of vanadium is low for Hubei ore. Acid leaching is more beneficial to the vanadium leaching but other extra methods, such as adding aid-leaching agent and/or increasing acid concentration is need for the ore where vanadium is embeded firmly. This study can effectively guide the selection of vanadium extraction techniques for stone coal from different regions.

Jan 1, 2014

By S. V. Petrov

Oxidised ores possess a significant share among raw materials which are treated by traditional plant technology. As usual, the chemical composition of these ores is rather simple. They can be treated by standard cyanidation. In this case, the resulting wastes have an alkaline reaction. Their toxicity (in case of ROM ores treatment) is mainly due to the presence cyanides and thicyanades. The tails are dexotified before disposal. However, chemical reagents used cannot provide a complete removal of toxic matters. In this case, this disposal poses a real problem because these tails contain a significant amount of CN and SCN and their behavior during a long disposal should be studied. A sample with a simple composition taken from cyanidation tails was studied. The sample presents itself the quartz low-grade sulfide gold-bearing ore. Sulfide sulfur content is 0.15 per cent,and heavy metals content is 0.023 per cent. Method of testing is described further. The samples were tested under moderate and subarctic climates based on the difference in temperature, moisture and the degree of oxygen saturation of air. The pH of water extract, which was prepared using distilled water, was also determined besides measuring the concentration of cyanides and thiocyanates. This demonstrates the stability of sulfide-bearing minerals in the disposed tails. The tests time was 820 days. It was found that the alkalinity of the samples tends to lower under oxygen-containing conditions in proportion to temperature increasing. Under conditions without oxygen, the pH lowering is minimal. Mineralogical and chemical properties of the ore material give positive alkaline balance during testing. The solid sample contains enough alkaline agents to compensate dangerous to the environment reactions of sulfides oxidation.pH value maintaining under alkaline conditions witnesses to the possibility of a safe disposal of this tails type. The largest amount of cyanide is removed under acid-containing conditions at positive temperatures. The higher the temperature is, the more intensive destruction is. At the moment, of finishing the tests at 20ºC temperature, the residual concentration of CN- was 0.06-0.10 mg/L, at 4ºC, the residual concentration of CN- was 0.2-0.3 mg/L and at -18ºC was 0.4-0.6 mg/L. Under conditions with the lack of oxygen, cyanides can be removed within the first 200 days. Then, this process fully stops. A stabilized cyanides concentration is 3.0-4.0 mg/L. The presence of sulfides increases the content of cyanides at the initial stage of testing. Then, the concentration of SCN at the temperatures above 0ºC decreases rapidly under oxygen-containing conditions. At the rise of temperature, a narrowing of peak at the curve and an increase of the destruction process are observed. At the end of testing, the concentration of thiocyanates in the moisture of wastes was 0.2-0.3 mg/L at the temperature of 20ºC and 0.5-0.6 mg/L at the temperature of 4ºC, respectively. The concentration of thiocyanates contained in a frozen sample and media which have the lack of oxygen stabilizes at a certain level owing to sulfides and does not practically change further. It was found that detoxification of oxidized cyanidation tailings with a simple composition which were disposed as filtration cakes can be possible. In this case, the concentration of cyanide in the moisture of disposed wastes can have a close value or equal to actual concentration during cyanidation. In order to meet the requirements of high ecological safety standards and successful detoxification process of toxic compounds in the tails under the action of natural factors, the conditions of air aeration with oxygen for the whole volume of tails are required. Keywords: cyanides, thiocyanates, storage, detoxification, flotation cakes

Sep 1, 2012

By Andrey Kozlov

The results of mineralogical?technological studies of PGM mineralization in zoned mafic?ultramafic complexes of the Ural?Alaskan type are given. The most important technological specificity of PGM mineralization hosted in dunites is its occurrence only in the form of free mineral species with predominance of Fe?Pt alloys (ferrous platinum, isoferroplatinum, and tetraferroplatinum). Technological properties, grain size, and good opening of PGM ore in grain size class +80 µm make it possible to concentrate ore using gravity methods with stadial comminution and between cycle separation of relatively large grains and nuggets into high-grade concentrates at the early stage of disintegration. Keywords: platiniferous dunites, PGM mineralization, mineralogical?technological studies and processibility research, recovery technology, gravity methods

Sep 1, 2012

By Mark Viduetsky, Dmitry Tropnikov, Victor Maltsev, Victor Sokolov, Alexander Purgin, Andrey Panshin, Alexander Bondarev, Pavel Kozlov, Igor Garifulin

"CFM pneumatic flotation machines were developed by the Institute of Materials Science and Metallurgy, UrFU, and designed to concentrate a wide range of ores and man-made materials. A key principle of work is pulp preparation for flotation owing to its saturation with finely dispersed air bubbles in ejectors. CFM plants, their advantages over domestic and foreign prototypes are described. CFM pneumatic machine commercialization resulted in: - machines demonstrated high floatation efficiency for concentration of rebellious pyrrhotite-bearing copper and zink by simultaneous floatation of copper and zinc minerals and depressing pyrrhotite. CFM- 1400M introduction allowed simplifying and optimizing the flow chart and increase extraction of copper - by 5.4%, zinc - by 9.5% and improve the quality of copper (3% Cu) and zinc (1.5% Zn) concentrates. - due to copper pyrite concentration by using CFM 1400M overall copper recovery was increased by 1.5 %, and the content of copper in concentrates - by1%. According to the results of pilot runs, the use of CFM flotation for zinc cakes concentration strongly intensifies the process of cleaning water-soluble metal compounds and, thereby, increases the efficiency of flotation concentration and subsequent milling. CFM machines showed higher specific capacity (three or four times higher) (both for feed material and froth product). Specifically, CFM froth product has higher content of useful elements (silver by 0.014 % abs. zinc by 0.31% abs.) and better extraction (silver by 6.08% abs., zinc by 0.31% abs., and sulfide sulfur by 13.7 %). Sulfide sulfur content of CFM product chamber as compared to mechanical flotation machines is two times lower (0.48 vs. 0.95 %)."

Jan 1, 2014

To extract the gold from refractory gold concentrate with high sulfur and arsenic, the gold concentrate was catalytically oxidized to expose the gold for cyanide leaching. The effects of reaction temperature, initial nitric acid concentration, reaction time and initial gold concentrate concentration on the conversion rate were studied. The results show that the appropriate conditions for the catalytical oxidation of this gold concentrate are: reaction temperature of 65 oC; initial nitric acid concentration of 25% (wt.); reaction time of 1.5 hours; initial gold concentrate concentration of 10% (wt.). Under such conditions, the conversion rate of gold concentrate is 92%. The solution can be used to prepare nano-iron oxide red pigment. Gases released in the process can be recycled and reused by oxidation absorption. A chemical background of catalytic oxidation is proposed.

Jan 1, 2014

By B. Z. Wu

The flotation of low-grade zinc oxide ore which from Guizhou has been researched by sulfuration- amine method. The experimental result indicated that when pH of pulp was 11, good flotation index can be achieved by using sodium silicate as dispersant, mixed amine as collector, and the do-sage of sulfur sodium was 6kg/t, and the recovery of zinc can be heightened by using copper sulfate as activator and Hydroxamicacid as collector. When the zinc feed grade was 4.84%, the zinc concentrates with grade of 39.23 % and recoveries of 75.17 % were obtained by adopting this technics.

Jan 1, 2014

By Graeme J. Jameson

"When mineral particles are floated in a mechanical flotation cell, it is found that the rate constant, after reaching a maximum value, starts to decline as particle size increases. It had been thought that the reduction in rate constant had been due to the increased prevalence of composite particles in natural ores, for larger particles. However, Jameson (2012) showed that the rate constant for composites is certainly a function of the surface liberation, but the reduction in flotation rate is independent of particle size. Thus all particles are equally affected by reduced surface liberation, independently of their size. He further argued that the classical peak observed in the rate constant with increasing particle size, is a function of machine hydrodynamics. Thus in mechanical cells, the peak may be due to the high energy dissipation rate and its effects on the detachment of particles from bubbles (Goel and Jameson, 2012). Consequently, in a different flotation environment, it may be possible to float large composite particles that cannot be floated in mechanical cells. This paper describes the flotation of large composite particles in a fluidized bed flotation cell. The particles to be floated are fed to a column in which there is a continuous upflow of liquid. A conventional froth layer of controlled depth is formed at the top of the vessel. A fluidized bed of particles is established which provides a gentle environment for the contacting of large particles with bubbles. An example is given where a porphyry copper ore was prepared at a top size of 710 µm, and floated with conventional collector (PAX) and frother (MIBC). The concentrate was separated into size fractions and examined by photography. Composites were observed at all size fractions, but above 400 µm, all particles were composites. The implications for future flotation circuits will be described."

Jan 1, 2014

By Pawel Strzalkowski, Marta Baszczynska, Urszula Kazmierczak

The paper presents issues related to interference of mining activities with the environment. Exploitation of mineral resources causes primarily a modification of the landscape. All of the negative impacts on environment are short-lived and last as much as it takes to exploit the raw material. After the mine closure reclamation is necessary during which all aspects that reduce harmful effects of the mining activities on the environment must be taken into account. Current ways of reclamation allow recreating natural environment, which is different from the original and enriched in diverse new values. This requires propositions of new forms of converted land development through a detailed analysis of technical, natural, planning, economic and social sphere requirements. Before making final decisions regarding selection of direction of reclamation, a thorough analysis of the key factors has to be carried out. All steps related to the implementation of the reclamation project are shown in the paper using Limestone Mine "Górazdze" located in the south-western part of Poland as an example. This paper also presents an analysis of current ways of post-mining reclamation towards agricultural and forestry landscape, along with our own suggestion for their extension in order to preserve biodiversity. For choosing optimal solutions the most relevant criteria were considered: existing natural values and possibility of their protection. Taking into account the economic and social aspects, supported by natural potentials, implementation of tourism and recreation in this area were proposed. It was shown that this proposition would not interfere with the current trends of the natural landscaping. Finally, after completion of reclamation and land development in the considered mine area, creation of a geo-park was proposed along with appearance of geotourism in the area. To illustrate the proposed forms of post-mining land development in the form of maps, an ArcGIS(ESRI) software was used.

Jan 1, 2014

By Barbara Peszko, Tadeusz Tumidajski

"Various methods are used to identify the grain composition of fine-grained materials because so far the best notion of the grain size has not found and there is no single method to define grain size. In practice the most important are the following grain sizes: sieve diameter dt, effective diameter de, substitute diameter d2 and statistical diameter dst. The mentioned sizes are connected with the methods of analyses. Methods are correct but measure of different diameters of grain and their results are different.The most important methods of granulometric composition analyses are the following: the sieve analysis, the sedimentation method and the conductometric (Coulter-Counter) methods. In each of these methods various physical features connected with the grain size are measured.Sizes of grains defined by different formulas or measurement methods are associated mutually by dependencies, which are results of differences in their determination or calculation ways.In order to determine principles of results comparison the classification analysis results on linearly or non-linearly connected was made. Analyses which results demonstrate the same type of grain size distribution are treated as linearly connected. It is based on the general formulae which determines the probability density function of random variable which is the function of another random variable having the known density function.In order to show the difference in the grain composition of the same material qualified by different methods, three methods of investigations were distinguished. They are: the sieve analysis performed on precise sieves, the sedimentation analysis performed by means of a sedimentation balance “Sartorius” and the microscopic analysis performed after preparing a microscopic slide where the grain size was measured by the Martin’s method.The materials selected for the analysis were quartzite and glass, which are the material of high purity.The obtained results of mentioned above three types of analyses were approximated by distribution function of four distributions: Weibull, log-normal, cut Weibull and Gaudin-Schuhman."

Jan 1, 2003

The Indian steel industry is growing at a rapid pace and expected to be the 2nd largest steel producer in the world after China. To cope up with this growth and to sustain it, the industry needs to focus on effective utilization of domestic metallurgical coals. While the importance of indigenous coal has increased, its supply from the domestic sources is declining. This is primarily due to high ash content in Indian coals leading to its difficulty in washing to a low level competitive to imported coals. Non-availability of a suitable beneficiation technology to bring down the ash to such a low level is the other reason. Effective utilization of current technologies has enabled Tata Steel to bring down the ash to 13-16% from its captive collieries. However, further lowering the ash using the conventional beneficiation technologies is difficult and unsustainable. New technologies should be developed for bringing down the ash further. A thrust area research program has been undertaken at Tata Steel for producing clean coal with 8% ash maintaining the yield currently achieved in its washeries. The technologies attempted are based on chemical beneficiation of coal. In leaching process, suitable chemicals are used for extracting ash minerals from the coal. As an alternative process, the combustible part of the coal is being extracted using a suitable organic solvent through an organo-refining process. Both the processes have been successfully developed in the laboratory and are being demonstrated in pilot scales. Various beneficiation processes practiced at Tata Steel including the efforts made for developing new processes for achieving clean coal with 8% ash have been discussed in this paper. Keywords: metallurgical coals, washing, beneficiation technologies, chemical beneficiation, leaching, solvent, and organo-refining process

Sep 1, 2012

By A. V. Faiberg

Currently, the interest to conditioning of cyanide-bearing recycled solutions with high-grade of base metals, in particular, copper has significantly grown. This can be explained by two major factors. Firstly, there are strict regulations on cyanides amount in tails and higher cost of detoxification processes. This problem can be easily solved during the ore treatment using the conditioning of solutions and water recycling. Secondly, the presence of other metals minerals which react with cyanide during gold leaching resulting in high cyanide consumption. The presence of copper is a major problem. Many copper minerals react with cyanide with the formation of cyanide complexes-Cu(CN)2-, Cu(CN)32- and Cu(CN)43-. One mole of copper consumes 2-4 moles of free cyanide. Availability of cyanide-soluble copper minerals has deleterious effect on gold leaching (gold recovery, cyanide consumption, tails detoxification, efficiency of gold elution and electrowinning). The precipitation of copper from the solutions improves gold recovery by CIL. The removal and recycling of cyanide allowed the reduction of cyanide addition to the process. The recycling of spent cyanide-bearing solutions based on the removal of copper and the return of cyanide bound in complex compounds for leaching process is an optimal way of solving the problem of gold-bearing copper ores treatment. By using the technology, an adverse impact onto gold recovery process is eliminated and at the same time reducing the cyanide consumption. Today, processes and methods of high-grade copper leaching solutions conditioning before and after gold recovery have been developed, which combine two ways of copper recovery: as a saleable product and cyanide to recover gold and reduce total operating costs. They are Cutech, MNR, SART, Cyanomet, AuGment, Vitrokele, Hannah and Cyanisorb. At the same time, these technologies have not been studied enough and described in literature. Data on parameters and operating conditions as well as introduction is not available. The conditioning technology of recycled solutions developed by IRGIREDMET JSC allows copper to be recovered as high quality concentrate and at the same time free cyanide regeneration in the recycled solution which is amenable to gold leaching. This technology was commercialized at a mine in Kazakhstan in 2008. The removal and recycling of cyanide does not require additional cyanide and is cost-effective. More cost-efficiency is achievable through selling copper concentrates, closed water cycle without the detoxification of effluents and enhanced gold recovery by CIL and cathode quality.

Sep 1, 2012

By Andrei Kolesnikov

"The results of CFD modelling of complex heat transfer and fluid flow in DC electric arc furnace are presented. The model includes energy and momentum conservation equations for gas phase (freeboard), liquid phase (molten bath) and solid phase (walls and graphite electrode). Simulation revealed the temperature distribution in all elements of the furnace. The influence of the arc and melt resistance on the temperature distribution is discussed.Computational Fluid Dynamics (CFD) becomes a powerful tool for better understanding of the heta and mass transfer processes in industrial equipment. In current work commercial CFD software STAR-CD was used to analyse complex heat transfer in DC EAF, including forced and natural convection, conduction and radiation. The finite volume solver using body-fitted grid was used. The grids are non-staggered hexahedral grids and all variables are evaluated at cell centers. Steady-state calculations were performed with PISO algorithm. For the convective terms in equations the hybrid differencing scheme was used. An upwind differencing scheme was used for other terms. Conjugative heat transfer was taken into account in heat transfer calculations on gas-liquid and gas-solid interfaces. Radiation from the arc and inner surfaces of the furnace was calculated by a “discrete beam” approach. Source term in energy conservation equation was used to represent heat release in the zone occupied by the DC electric arc. The volume of this zone was calculated from semi-empirical equations. The Joule heat and heat due to chemical reaction in the melt were calculated through the source term expression in the energy balance equations for the slag and metal in the molten bath. The gas acceleration in the electric arc zone and stirring of the slag due to gas bubbles motion were accounted for by momentum source terms in the momentum conservation equations.All simulations were carried out using axisymmetric two-dimensional grid. The grid resolution was 20 cm per cell in most part of the furnace, except the arc region, where resolution was 5 mm per cell."

Jan 1, 2003

By Weiguo Xie, Malcolm Powell, Lian Liu, Ping Yu

"In order to develop a common mathematical and simulation platform for tumbling mills, a review of existing mechanistic models was made identifying the key aspects of grinding and slurry transport which are common to all tumbling mills. A mill model structure has been developed for all types of tumbling mills based on the population balance framework by incorporating breakage characteristics, slurry and solids transport, product classification and discharge, and energy consumption. A size-dependant breakage model developed by the JKMRC is applied. Transport is separated from breakage events and treated as a main sub-model in the new model structure. The model structure is based on dynamic time-stepping technique to enable dynamic simulation capability for non-steady-state simulation and control modelling. It is envisaged that the new model will cover a full range of milling conditions. It should enable a smooth transition between different mill types, such as from AG (Autogenous Grinding) to SAG to ball mill. The dynamic mill model structure developed here is the first step towards mechanistic modelling of grinding mills and provides great potential for the optimization of the comminution process."

Jan 1, 2014

By Atul Kumar Bhatnagar

TATA STEEL is the pioneer in coal beneficiation in India. The first coal beneficiation plant was set up in 1951 at West Bokaro and subsequently in 1953 in Jharia. Over the years more beneficiation capacity was added by setting up new coal washeries in both West Bokaro and Jharia, the coal divisions of Tata Steel. currently the beneficiation capacity available is 8.5 mtp aappx Being a captive supplier supplying the coking coal as per demands of our steel works is challenging in the sense that the intent is to leverage the captive raw material advantage and select the best strategy for maximizing value up to steel making. The beneficiation plants were designed to produce clean coal up to 17% ash. With the demand of increasing productivity at the blast furnace the clean coal ash was lowered. subsequently the processes were audited and efficiency improved. The next challenge was to improve the throughputs in the existing plants to maximize the clean coal production. The upgradation was designed in house and implemented to upgrade the plant from nameplate capacity of 2.1 mtpa to 4.5 mtpa while the yearly production targets were also achieved. The presentation will detail the different phases of improvements, process followed, challenges faced, and the results as achieved in the process. Keywords: coal beneficiation, India, coal washeries, beneficiation plants XXVI INTERNATIONAL

Sep 1, 2012

By J. Broadhurst

"A number of metal supplying industries have in recent years seen the compilation of life cycle inventories (LCIs) and life cycle assessments (LCAs). The activity has largely been driven by the interest of ultimate metal users, such as the automotive industry, in the interest of designing more sustainable products. Often, the compilation of such inventories has been little more than an auditing exercise. However, the process of conducting an LCA can have more value, guiding designers and operators to points within the technology train where significant emissions and impacts originate. The LCA product can thus be used to inform on-site environmental management, and, where process data is used to construct dynamic operational models, to support strategic decision making in the realm of project planning and technology selection. LCA thus serves as a valuable tool to support the industry’s drive to support the sustainable development of the societies in which it operates.This paper reviews and compares the priorities of environmental and closure planning in the design phase, with environmental management and auditing during operation, and with green procurement of minerals and metals products. It shows how life cycle assessments of various complexities can be used to reconcile these various objectives, ensuring that the latter, critical to business success, can be addressed from the outset in a new project. The paper then reviews a case study of the use of LCA in the base & precious metals industry, where the complexity of the operation disallowed the simpler auditing process so that a detailed process understanding had to be built up in order to compile a meaningful life cycle inventory."

Jan 1, 2003