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By Bronwynne K. Williams

"In deriving flotation kinetic models, the froth phase was, until recently, either ignored or treated entirely empirically. The behaviour of the froth is now known to be usually important and sometimes dominant in determining flotation performance. Hence numerous methods have been developed for sampling the flotation froths and models incorporating the effects of the froth behaviour have been derived.Such models will assist in determining more accurate estimations of the kinetic parameters utilised in the designing of industrial scale plants thus reducing the incurred costs of over designing. In particular, improved models for batch tests may lead to more effective use of batch testwork for prediction of continuous plant behaviour. A more detailed model is thus proposed which allows for a more realistic approach to the flow distribution in the froth phase.PROPOSED MODELThe batch flotation process is split into two stages in time, namely before the froth begins to overflow and after. The assumptions made, and hence the calculations, are different for each stage.The air enters the slurry at t=0 and generates froth. The superficial velocity of the air through the cell is given by go. It is assumed that the rate of froth breakage (gb) is constant during the first stage. The froth rises with a uniform net velocity throughout the cell and no mixing is assumed to occur.After the froth begins to overflow, the velocity distribution of the gas is modeled by segmenting the froth phase as shown in Figure 1. A model for bubble breakage rate or measurements of froth velocity allows one to obtain the volumetric rate of concentrate froth production. The entrained water and associated particles and a drop-back mechanism are also allowed for in the model."

Jan 1, 2003

By Shuji Owada, Mayumi Ito, Idemitsu Kosan Co. Ltd., Takehiko Nishimu, Sadayuki Shinozaki, Takashi Ando, Tomoe Ota

"fElectrical disintegration (ED) by high voltage electrical pulse is a relatively new technique which was demonstrated by Tomsk and Mekhanobr in the 1960’s and has been investigated in detail by Andres in the 1990’s. In the ED, the electrodes should contact to the targeted material and the energy of high voltage pulse is charged directly to the material. It has been reported that the ED is quite efficient to improve liberation of composite materials, because electrical current passes often through the conductive part and/or along the phase boundaries. Theoretically, the energy required in the ED should be lower than in the other mechanical breakage methods, because breakage occurs basically by tensile strength in the ED while in the other mechanical methods it does mainly by compressive strength which is generally ten times or higher than tensile strength.Coal, involving many kinds of mineral matters, is considered to be one of the targets for the ED to apply to. In Japan, national “Hyper-Coal Project” is now running, in which ultra-clean coal (less than 200ppm of ash, 0.5ppm of Na and K, and 2ppm of Ca) is planned to produce by combining advanced coal preparation and liquefaction technologies for the purpose of direct injection of coal combustion gas to turbine. The ED is one of the major techniques to be developed in this project, since mineral matters must be liberated before introducing to the following advanced separation processes. Liberation is important also for the utilization of middling coals generated from usual coal preparation plants. The application of the ED to the middling coals is considered effective for upgrading these coals with higher liberation degree and less energy input."

Jan 1, 2003

By Dingwu Feng, Jannie S. J. van Deventer

"The effect of ultrasonication on reactions at solid/liquid interfaces was investigated by using an ultrasonic probe in two slurry systems, i.e. cyanidation of a refractory sulphide ore and geopolymerisation of metakaolinite. The surfactant dithiophosphate was used to render the gold bearing sulphide particles hydrophobic, in an attempt to induce the formation of cavitation bubbles directly at the desired surfaces. Oxygen was injected into the cyanidation system to improve the attachment of oxygen bubbles to the hydrophobic sulphide surfaces. Geopolymerisation occurs in highly alkaline solution with waste aluminosilicate oxides and silicates as the reactants. The process of geopolymerisation is believed to involve dissolution of Al-Si oxides from solid particles, diffusion of dissolved Al-Si complex from the solid surface into the gel phase, condensation of gel phase and hardening of the gel phase. It has never been investigated how ultrasonication affects the above steps in synthesising geopolymers, despite a number of papers dealing with sonochemical synthesis of materials. The introduction of power ultrasound into such slurry systems is expected to result in advanced geopolymer materials.In the cyanidation of the pyrite concentrate, the kinetics of gold extraction were significantly enhanced in the presence of ultrasound, due to the prevention of passivation and the enhanced dissolution of sulphides. Cyanide consumption was significantly reduced with ultrasonication, owing to the oxidation of soluble sulphides to sulphate, minimising the cyanide consumption by sulphides. With oxygen injection, ultrasound significantly enhanced the leaching of gold from the pyrite concentrate, as oxygen could enhance the formation of the oxidation radicals by ultrasonic cavitation. In the presence of dithiophosphate, ultrasound further improved gold leaching in the oxygen-aerated system. Dithiophosphate could selectively adsorb at gold host sulphide surfaces, and make the surfaces hydrophobic. As a result, the ultrasonication effectiveness could be enhanced through forming cavitation bubbles directly at the interfaces."

Jan 1, 2003

By Valentin V. Shatalov, Irina V. Pastukhova, Alexander V. Kurkov

"We have developed a technology to improve the quality of low-grade concentrates containing minerals of tantalum, niobium and tin on the basis of given conception by the way of improving selectivity and using certain reagents composition. The basic collector presents a traditional or complex-forming collector used together with organic diphilic reagents – the secondary reagents regarding the basic flotation regiment, capable of forming associates with the main collector on the surface of the mineral, thus altering the interaction energy. In the given process the main collector is the fraction of hydroxamic acids C7-C9, the reagent of the secondary action – sulphosuccinamate, which added in moderate concentrations range provides for a synergistic effect.We have determined the parameters of the process stability and necessary modifying reagents for a selective recovery of tantalum, niobium and tin minerals from refractory products. Variants have been studied where the main collector and the secondary action reagent were substituted with some more efficient flotation reagents. A possibility of a more flexible reagent compounding for the process has been shown. The flotation process is highly stable regards the saline composition of the liquid phase in the pulp. It can operate under conditions of the complete water recycling with the total salt content up to 12 kg/m3, iron up to 1.2 kg/m3.The given results consider the efficiency testing of the suggested technology for the gravitation products, which were obtained from ores of various genesis and contain large quantity of the most refractory minerals, such as topaz (80%), gamet (55%), tourmaline (30%). High selectivity of the process has been registered with the metal recovery about 92-98%, which appears to be similar to hydrometallurgical operations under certain conditions."

Jan 1, 2003

By Chris J. Martin, Nichola A. McKay

"In mid-2001, North American Palladium commissioned a new 15,000 tonnes per day milling and flotation circuit at their Lac des Iles Mine (LDI), one of only two primary platinum group element (PGE) producers in North America. The mill treats an ore containing 2.3 g/t PGE producing a concentrate assaying 300 g/t PGE, at a recovery of roughly 75%.Top-size control crushing is conducted ahead of semi-autogenous milling. A portion of the SABC circuit feed is crushed to –25mm to increase mill throughput. Product from the SABC circuit is fed to flotation. Flotation consists of roughing and scavenging, with the rougher and scavenger concentrates each being reground using vertimills. Cleaner flotation uses two stages of cleaning using mechanical cells, and a third stage using flotation columns, the column tails being scavenged using a bank of mechanical cells. Rougher concentrate by-passes the first cleaner circuit. Reagents added include amyl xanthate collector, dithiophosphate promoter, MIBC frother and a carboxy methyl cellulose-based gangue depressant.SGS Lakefield Research, together with staff at LDI initiated a structured plant optimisation program comprising on-site testing, bench-scale flotation and mineralogical analysis using QemSCAN. The objectives of the mineralogical studies were 1) to identify feed PGM, their size distribution and mineral associations, 2) establish relationships between the PGM mineralogy and PGM floatability, and 3) characterize the culprit silicate minerals diluting the final concentrate.PGM flotation response at Lac des Iles is clearly bi-modal in nature, with about 60% of the PGM floating quickly, to a high value rougher concentrate. The mineralogical work was able to explain the causes of the bi-modal PGM floatability, which in turn created new opportunities for the metallurgists to optimise the circuit."

Jan 1, 2003

By Williams Calderon, César Arredondo, Gonzalo Montes-Atenas

The quality of final concentrate in froth flotation circuits is largely dictated by the correct implementation of the froth washing operation in flotation cleaning stages, which are commonly installed in column flotation cells. In flotation plants, this aspect has been largely overlooked and the froth washing is restricted to the use of perforated piping through which process water flows producing a similar effect to that observed in "fountains": jet created with low energy crosses the froth phase washing out entrained particles as well as particles weakly attached to bubbles. The aim of this research study is to assess the efficiency of traditional froth washing systems theoretically and experimentally. A theoretical model was implemented using Fluent® software where a jet of variable speed was introduced in a continuous soft matter phase with physical properties similar to those observed in a froth phase in wet and dry conditions. In addition, a simple experimental protocol was designed to validate the model. It was found that the water process jet-like flow influences the behavior of 2 to 3 times the equivalent volume in the froth phase. Such influence zone is dramatically reduced as the froth phase becomes drier. These results were confirmed by the experimental findings indicating that a better froth washing technologies must be assessed and implemented. Some aspects of the ideal froth washing system are derived and discussed in details.

Jan 1, 2014

By Vladimir S. Zharov, Vyacheslav A. Tsukerman

"Conceptual imitative dynamic model of developing enterprises for medium and long-term period permitting to ensure coordination of interests of the enterprise and territorial environmental authorities has been developed to enable the process of the prognostication and management of a concentrating mill development, in which a symbol language and terminology familiar to the manager of the company are applied. An algorithm of practical application of this model of company development was elaborated as well as a general methodological approach to the prognostication of the development and procedures of its implementation. The general methodological approach to the implementation of the model has been defined. Within the framework of system approach, a concentrating mill is considered as a subsystem of an ore mining and processing company or a mining and smelting one. A concentrating technology is considered in dynamics, its change is determined by the task of making the company operation profitable. Technological indicators are secondary relative to financial and economical indexes. At the same time, technological and economical indexes are determined in their interrelation with ecological parameters. The elaborated model allows us to estimate all necessary economic, financial and technological indexes in their interrelation both for the company as a whole and as separately redistributed estimating the basic prognostication documents - accounting balance-sheet, profit and loss report, as well as the funds flow statement. When varying the managing parameters, all necessary result-producing financial and economical indexes are estimated and a need in and a possibility of an external funding by various sources are considered.The implementation of the model enables one to determine the required scale of production capacity, as well as the amount of raw-material resources needed. In case of shortages of the latter, there should be considered various scenarios of the production capacity enhancement or the possibility of commissioning of new sites or deposits and introduction of improved technologies."

Jan 1, 2003

By Kobus (J. J. ) Rossouw, P. Chris Pistorius, Johannes Sono

"Different coal properties are important in SL/RN (coal-based rotary kiln) direct reduction of iron ore, and in electrical smelting of prereduced iron ore. Laboratory simulation was used to evaluate two candidate coals, which were similar in volatile content and rank, but differed in reactive maceral content. The tests served to evaluate both the reduction rate (during direct reduction) and the dissolution rate of carbon from the coal into an iron bath.Reduction rates of mixtures of magnetite and devolatilised coal were assessed isothermally, using samples of 55 grams. The off-gas analysis was used to follow the extent of reduction. Results are shown in Figure 1 a). Coal B was expected to be more reactive, based on its higher content of reactive macerals (77%, compared with 61% for Coal A). In line with this, Figure 1 a) does show a higher reduction rate with this coal. However, increasing the reduction temperature increases the reduction rate substantially,especially for the less-reactive Coal A.For the dissolution experiments, samples (mass: 250 g) were melted in an alumina crucible (under a nitrogen atmosphere), to give a starting composition around 1%C. When the desired temperature was reached, 25 g of char was added on top of the melt, through a feeding port. Results are shown in Figure 1 b). The more-reactive Coal B was less crystalline (the graphite crystallite size estimated from X-ray diffraction was 4.6Å, compared with 11.4Å for Coal A). This is associated with a lower dissolution rate in iron."

Jan 1, 2003

By S. M. Marr

"Water availability and water-related environmental impacts are now one of the most significant challenges facing primary production within the global minerals industry. Whereas the industry has, to a large degree, been able to demonstrate a collective response to greenhouse gas emissions and global energy demand, no such strategy exists for water. In part, this is because water quality and availability are regional issues, but also too because water quality cannot be defined by a single attribute, and extrapolation of any set of water quality indices to their associated environmental impact is no trivial matter. In design situations specifically, the situation is exacerbated by the fact that process engineers typically focus on site water management, and consent authorities are primarily in catchment level issues. As a result, an integrated approach to water management is difficult. This does not stem from an unwillingness by members of the professional team to engage with the total picture of water quality and availability, but principally from the fact that there is no common language through which to approach the problem.It is imperative for process engineers to extend their design system boundary, to reflect the geographic scales over which water impacts need to be quantified. It is not suggested that chemical engineers and metallurgists should become experts in geochemistry, hydrology and limnology. Rather, the challenge is to develop tools through which better communication of the relevant environmental impacts can be achieved.It has been estimated that 50% of the capital for new plants is devoted to handling wastes. The integration of mass exchange processes, adopting a life cycle analysis framework for considering environmental impacts and shifting the emphasis from effluent concentration to environmental impacts should be adopted in the framing of the design problem have been suggested as techniques of Environmentally Conscious Design. Shifting the focus from effluent concentrations and legislative requirements to evaluating the environmental impact is an important step towards improving the overall environmental performance of a process facility."

Jan 1, 2003

By M. Özer, G. Önal, F. Arslan

"The use of ultrasonic in industrial processes has increased during the last few years. Ultrasonic vibrations are used in sieving, grinding, ore washing, cleaning, and flotation in mineral industry. There are also some attempts for the utilization of ultrasonic treatment in separation and removal of fine particles from gases and liquids. In Kalemaden A.S. (Turkey) four different types of clay mixtures (1. A mixture of clays from Balikesir-Düvertepe and Istanbul-Sile, 2. A mixture of clays from Ukrania and Balikesir-Düvertepe, 3. Sögüt-Kadikelimesi, 4. A mixture of clays from Sögüt and Istanbul-Sile) and kaolin from Balikesir-Düvertepe (Turkey) are concentrated before their use in ceramic production. Dewatering is the important step in those types of concentration plants. Sedimentation of concentrated clay has always been difficult and taken long times due to their nature and having small particle sizes. Flocculants can be used to enhance the sedimentation, but they are not preferred by the ceramic industry since they affect the quality of ceramic products. For this purpose, ultrasonic treatment is used in the sedimentation of clays mentioned above for solving the problems encountered related to the ceramic industry and promising results were obtained.Kaolin sample, subjected to this experimental study, from Balikesir-Düvertepe region of Turkey was brought from the plant as a pulp in containers and throughly mixed with a stirrer before sedimentation experiments. A two liter graduated cylinder and an ultrasonic bath (with 25 kHz frequency and 0.5 KW power) were utilized in the tests. Superfloc A-120 (1% concentration) was used as a flocculant. The settling distance was reported against the settling time during the experiments. Initial and final pulp densities were also determined. The effects of several parameters such as pulp density, flocculant addition, and ultrasonic treatment on the sedimentation of kaolin were investigated and the results are represented in terms of settling distance versus settling time."

Jan 1, 2003

By Felix M. Zhuravlev, Vitalij P. Lyalyuk

"While there is a large industry based on recovering platinum group metals (PGM) from complex sulphide ores containing Cu and Ni, there is little information on the thermodynamics of the matte phase formed on smelting the ore and in particular the behaviour of Pt in the matte.The equilibrium between metallic platinum and industrial mattes was studied in a series of experiments where a small quantity of matte (5g) and platinum foil of 150 µm thickness (0.5 g) were equilibrated in magnesia crucibles at 1400°C under conditions where the oxygen and sulphur partial pressures were controlled.The chemistries of the phases were determined from EDS analysis using a scanning electron microscope. Line scans were initially used to confirm that the foils had attained a uniform composition across their thickness. The composition of the matte was determined from analysis of an area of matte including the small metallic droplets and dendrites.The distribution of Pt in Cu-Fe-Ni mattes (Pt: 1.5 – 3%) and solid Pt alloys (Pt: 54 – 72%) was studied. For a matte of base composition 45%Fe, 11%Ni, 8% Cu, at a base temperature 1400°C, the following behaviour was observed for the Pt distribution ratio:Under the range of sulphur and oxygen pressure of this study (log pO2 from -15 to –12.2, log pS2 from – 4.6 to –2.2), the distribution ratio of Pt between matte and alloy was independent of the sulphur and oxygen pressure, having a value of 0.04.The Pt distribution ratio increased from 0.02 to 0.08 with temperature from 1340 to 1450 oC.For mattes where the proportions of Cu and Ni were kept constant, a slight decreasing trend was shown for the distribution ratio of Pt versus the iron content (37 to 53%) in the matte but was not confirmed because of experimental uncertainty."

Jan 1, 2003

By Vladimir G. Kochnev

"Autogenous and semi-autogenous grinding (AG and SAG) have been considered a step forward in comparison to conventional grinding circuits with several stages of crushing and using ball (and/or rod) grinding mills. However, existing AG and SAG technologies still can be improved and have an immense potential from the viewpoint of economic benefits.Experience gained by the Technics & Technologies of Disintegration Ltd. (TTD) in the research of grinding processes shows that comminution in AG and SAG mills can be performed in a more effective way. The company’s approach comprises the following elements:- Novel mill design- New liners and lifters- Novel discharge grid design- Technique of treating material of critical particle sizeA novel mill of the cantilever type capable to operate in the AG and SAG mode has been developed. The cantilevertype mill has a high diameter to length ratio, which dramatically increases the throughput rate, and is characterised by high reliability, fast installation and low capital and operating costs.Tests of the new heel-shaped liners, originally aimed at improving the intact condition of diamond, indicated that they play an important role in the grinding process. Tests performed by TTD jointly with ALROSA, MINTEK and Anglo-American Corporation, demonstrated that the heelshaped liners provided the increase in the throughput rate varying from 30 to 80 % and the decrease in power consumption in the range 30-55 % for grinding of kimberlite and platinum-containing ores.Investigation of the influence of the main grid parameters on the efficiency of grinding led TTD to a special design of a mill discharge grid, with a radial location of openings, the slot width varying from the periphery to the centre and the grid surface provided with “heels”. The design allows one to control the particle size distribution of the ground product without affecting the grid throughput rate."

Jan 1, 2003

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 Andrew D. McCallum, Russell A. Heins

"Until the advent of intensive cyanidation, gold gravity concentrates were generally treated by tabling. The table concentrates were smelted while table middlings and tailings were recycled to the milling circuit for further grinding and subsequent leaching in the CIP/CIL circuit. Gold recovery on production tables is relatively low, often only 30 percent, and rarely above 60 percent. Significant factors in tabling performance are; mineralogy and the operator’s experience and ability. Units have been developed by Gekko Systems to treat both batch and continuous gold concentrates. Unit sizes are determined by leach kinetics and the required residence time of the concentrate in the unit.Gekko commenced the commercialisation of intensive leaching of gravity gold concentrates in 1997 with the first commercial prototype of the InLine Leach Reactor (ILR). Over 20 units are now installed worldwide with half that number on the African continent. South African mines, South Deeps (Placer Dome WAJV) and Target (AvGold) have both installed InLine Leach Reactors. Ashanti Goldfields have placed the ILR on their standard equipment list and have six operating units with a seventh on order. AngloGold installed one of the first ILR production units at Morila in Mali.Gekko Systems successfully installed an ILR1000 Batch unit at the Antapite Mine in Peru in December 2002. The unit was installed to treat gravity concentrates and to replace a shaking table. Following installation, gravity gold recovery increased from 15% to 40% of total gold. The unit was operational from start up and the first gravity batch treated achieved 98% gold recovery. The gravity concentrates also have a high silver content and 95% recoveries on silver were also achieved.Preliminary testwork identified that the concentrates required additional oxygen to achieve peak performance. As a result of optimisation work in the laboratory, leach kinetics in the ILR have been excellent with only 6 hours residence required to achieve maximum gold extraction."

Jan 1, 2003

By M. H. Moys, H. Dong

"Discrete Element Method (DEM) has become a standard tool to simulate grinding mills in order to gain information about load behaviour, power drawn, etc. However, parameters necessary to run a simulation are not always readily available. For example, the coefficient of restitution used in DEM simulation from the literature ranges from 0.1 to 0.9 due to lack of accurate values. The lack of correct input parameters results in the fact that some simulation parameters are adjusted to match the simulation prediction with the experimental results. It is inappropriate to tune one single parameter arbitrarily in order to fit the prediction with experimental results. The correct value of parameters for DEM simulation should be established, and rigorous validation on simulation results by DEM needs to be done.The objectives of the ongoing project are to measure the coefficient of restitution at conditions analogous to grinding practice. Equipment has been built to measure the coefficient of restitution. A typical case of impact test showing the vertical position of a ball as a function of time is presented in Figure 1. The coefficient of restitution between steel ball of different sizes and the targets including steel liner (e = 0.91), mild steel block (e = 0.57) and rubber liner (e = 0.7) have been measured. The coefficient of restitution reduces to 0.38-0.52 when there is a layer of coal particles (1-2 mm) on the steel liner. The effects of ball size, drop height on coefficient of restitution are investigated. Then a DEM code is developed of several contact models to simulate the impact process. This code can reveal details on velocities (translational and rotational) and forces (normal and tangential) during the brief impact interval. Figure 2 is a comparison of the rebound rotational velocity between experiment and prediction by different models. The results can be used as DEM input and to assess contact models."

Jan 1, 2003

By Grigori I. Voiloshnikov

"The long-term studies on development of the technology for precious metals recovery using activated carbons executed by Irkutsk Research Institute of Precious and Rare Metals and Diamonds (IRGIREDMET) were finished by successful introduction of ""Carbon-In-Pulp"" process in Russia (1984).The review of some studies, accompanied by development, testing, introduction and subsequent improvement of considered technology, carried out by IRGIREDMET is submitted in this paper.The basic regularities of gold and silver adsorption onto activated carbons from cyanide, thiourea, chloride and other solutions are investigated using various phisical-and-chemical methods ( X-ray photoelectron spectroscopy, Voltammetry, X-ray microanalysis etc.). Using voltammetry it was found that gold cyanide is adsorbed onto activated carbon without chemical changes and partial reduction of gold is possible only during drying of carbon samples before analysis. Metallic gold and silver may be dissolved in boiling cyanide solution at argon atmosphere when they are in contact with activated carbon surface. Gold adsorption mechanism for activated carbons has great differences from that for the ion exchange resins. So the most probable mechanism for gold adsorption from cyanide solution is adsorption of neutral molecules Me n+[Au(CN)2-]n.X-ray quantitative microanalysis technique was developed to investigate gold adsorption kinetics onto spherical activated carbon. Gold profiles in granules of activated carbon for various adsorption conditions were tested (carbon particle size, mixing efficiency, adsorption time etc.). Mathematical methods were used to determine gold diffusion coefficient within activated carbon granule.The properties of various types domestic and foreign activated carbons were tested and the demands to activated carbons suitable for gold extraction were determined. As a result foreign and Russian activated carbons AG-90, AG-95 were recommended for use at Russian gold plants. Domestic adsorbents are cheaper in comparison with foreign activated carbons. The methods to restore carbon adsorption activity including acid treatment and thermal reactivation were tested and implemented."

Jan 1, 2003

By Tim Suljada, Mary Stewart, Jim G. Petrie, Damien Giurco

"The minerals industry is being challenged to reduce the amount of virgin ore that is mined, and to replace this material through the recycling of used commodity items and scrap, or by the reprocessing of waste materials. It is argued here that the existing technology base of minerals processing and refining offers real potential for handling these secondary resources. The challenge is to develop tools by which the most preferable recycling routes (both economically and environmentally) can be identified from a list of feasible alternatives, taking into account any operational constraints of these technologies.This paper describes an heuristic approach to developing the family of all technically feasible flowsheets to address this challenge, from which a preferred option may be selected according to a set of decision criteria (economic and environmental). Our approach uses conventional flowsheeting techniques of selecting flow variables and splitter functions, supported by design performance information for each unit operation. This set of design decision variables is augmented by knowledge of the suitability of a particular waste or scrap stream for a given unit operation within a flowsheet. We achieve this by comparing the composition of the scrap stream with the range of mineral streams for which the unit operation was designed initially. This is inspired by the “overlap” approach proposed by Legarth, where an “overlap” of 1 would suggest that there is high degree of compatibility between a given secondary resource stream and a primary mineral stream as inputs to a specific technology. The “overlap” concept has been extended to include information about the physical characteristics of secondary resource streams, as well as information relating to synergistic / antagonistic influences of minor elements present in the waste stream. A flowsheet which delivers a product of acceptable quality from a given secondary resource material is built up from a progression of unit technologies. The exercise is repeated to generate the family of all feasible flowsheets from combinations of acceptable unit technologies."

Jan 1, 2003

By A. T. Sutaone

"Battery grade Mn ore is not found in India except in Dongri-Buzurg Mine, Dist. Bhandara, Maharashtra. The mine located in central India is operated by a premier company viz. Manganese Ore India Ltd., under Central Government Public Sector Undertaking. The company is not selling the product as battery grade material but instead primarily catering to the needs of the iron and steel industry in the country. However, a part of the ore is being used in-house for the production of electrolytic manganese-dioxide in their EMD plant, which is located near the mine.The production of lumpy ore for steel industries generated through multi-stage crushing and screening has resulted in accumulation of about 50,000 tonnes of low grade fines over the year, which contain low of Mn values. Further, the generation of fines is still on going process due to the production of lumpy ores. These fines are stacked in the form of unconsolidated dumps, which create environmental problems like air and water pollution and siltation in the adjoining fields. Besides they are occupying large space, which is scarce in this mining area. The Indian Bureau of Mines under one of its statutory functions has suggested the company to explore the possibility of recovery of additional values under conservation and environmental aspects. Hence the company has sponsored a bulk sample for beneficiation studies in the Modern Mineral Processing Laboratory and Pilot Plant of Indian Bureau of Mines at Nagpur, India. The main manganese minerals present in these mine rejects have been identified as pyrolusite and psilomelane. The purpose of this study was to explore the possibility of evolving a suitable beneficiation flowsheet to obtain manganese concentrates assaying over 72% MnO2 to be used as raw material for the manufacturing of dry cell batteries."

Jan 1, 2003

By Steven Wright, Sharif Jahanshahi, Shouyi Sun

"While there is a large industry based on recovering platinum group metals (PGM) from complex sulphide ores containing Cu and Ni, there is little information on the thermodynamics of the matte phase formed on smelting the ore and in particular the behaviour of Pt in the matte.The equilibrium between metallic platinum and industrial mattes was studied in a series of experiments where a small quantity of matte (5g) and platinum foil of 150 µm thickness (0.5 g) were equilibrated in magnesia crucibles at 1400°C under conditions where the oxygen and sulphur partial pressures were controlled.The chemistries of the phases were determined from EDS analysis using a scanning electron microscope. Line scans were initially used to confirm that the foils had attained a uniform composition across their thickness. The composition of the matte was determined from analysis of an area of matte including the small metallic droplets and dendrites.The distribution of Pt in Cu-Fe-Ni mattes (Pt: 1.5 – 3%) and solid Pt alloys (Pt: 54 – 72%) was studied. For a matte of base composition 45%Fe, 11%Ni, 8% Cu, at a base temperature 1400°C, the following behaviour was observed for the Pt distribution ratio:Under the range of sulphur and oxygen pressure of this study (log pO2 from -15 to –12.2, log pS2 from – 4.6 to –2.2), the distribution ratio of Pt between matte and alloy was independent of the sulphur and oxygen pressure, having a value of 0.04.The Pt distribution ratio increased from 0.02 to 0.08 with temperature from 1340 to 1450 oC.For mattes where the proportions of Cu and Ni were kept constant, a slight decreasing trend was shown for the distribution ratio of Pt versus the iron content (37 to 53%) in the matte but was not confirmed because of experimental uncertainty."

Jan 1, 2003

By Georgios N. Anastassakis

"The depletion of the high-grade chromite ores and the inefficiency of the gravimetric methods to process fine particles has shifted the industrial and research interest from gravimetric separation methods to flotation. However, the response of the minerals to various flotation schemes is not clearly established. In this work, the physicochemical behavior of chromite and olivine is studied using a fatty acid collector.The minerals used were from Vourino area (Kozani, Northern Greece). Macroscopically pure samples of chromite and olivine were selected by hand picking, crushed and subsequently ground to the required size. Each sample was then submitted to panning and magnetic separation for the removal of impurities. The mineralogical and chemical analysis of the purified samples revealed the following: a) The purity of chromite was 95% while the minor constituent was mainly magnetite. Its chemical analysis was: 12.50% Fetot, 2.50% SiO2, 54,54% Cr2O3, 9.31% Al2O3, 0.47% CaO, 13.10% MgO. These analyses show that Cr3+ has been substituted by Fe3+ and Al3+ as well as Fe2+ has been significantly substituted by Mg2+. b) Forsterite is the main constituent of olivine either as pure forsterite (Mg2SiO4), which is the prevailing form, or as iron-forsterite [(Mg,Fe)2SiO4] in less amount. Chrysotile, which belongs to the serpentine group, was also detected at a percentage of 10-15%. The chemical analysis of olivine was: 36.90% SiO2, 0,53% Cr2O3, 7,43% Fe2O3, 0.72% Al2O3, 0.91% CaO, 47.00% MgO, 6.02% LOI.The electrokinetic behavior of the minerals was studied in a electrophoretic mass transport equipment Model 1202 of Micromeritics. The reagents used were sodium hexa-metaphosphate of commercial grade and sodium oleate."

Jan 1, 2003