Showing papers in "Mineral Processing and Extractive Metallurgy Review in 1992"
TL;DR: In this paper, the equipment most commonly used in fine particles processing and related process parameters is described, including Tumbling ball, stirred, vibratory and fluid energy mill types, and a number of factors influence the choice of equipment, including the end-use of the product, required product size distribution, sensitivity of the material to heat and purity requirements.
Abstract: The growing demand for ultrafine powders, coupled with stringent quality requirements, calls for continuous improvements in all aspects of fine particles production. The high energy costs involved in comminution is also an additional motivator. The equipment most commonly used in fine particles processing and the related process parameters is described. Tumbling ball, stirred, vibratory and fluid energy mills are the most commonly used mill types. A number of factors influence the choice of equipment, including the end-use of the product, required product size distribution, sensitivity of the material to heat, and purity requirements. Stirred ball mills are used in ultrafine grinding because of their high unit outputs, while the low amplitude vibro-energy mills are used because of their low specific energy. Fluid energy mills are economic only in some specific applications as in treating heat sensitive materials, materials for plastics and ceramics where purity and delamination are the most important crit...
63 citations
TL;DR: Froth flotation of iron oxides and quartz is reviewed over the broad range of particle sizes in this paper, which embraces laboratory-, pilot plant-and industrial operations, encompassing surface chemistry of IR and quartz flotation, relevant collectors and their adsorption mechanism and activation/depression in selective flotation.
Abstract: Froth flotation of iron oxides and quartz is reviewed over the broad range of particle sizes. The review, which embraces laboratory-, pilot plant- and industrial operations, encompasses (i) surface chemistry of iron oxides and quartz flotation (ii) relevant collectors and their adsorption mechanism and (iii) activation/depression in selective flotation, in this system. The diverse effect of temperature on iron oxides and calcium-activated quartz flotation is also indicated; the flocculation-flotation process of upgrading fine-grained iron ores is highlighted; and the economic advantage of reverse flotation in high grade, coarse- or medium grained iron ore flotation circuits is noted.
46 citations
TL;DR: In this article, the pulp potentials in the flotation of sulfide minerals are investigated in terms of the mixed potential model for both self-induced and collector-induced flotation.
Abstract: Interpretation and implications of pulp potentials in the flotation of sulfide minerals are presented. Mechanisms of sulfide flotation are reviewed in terms of the mixed potential model for both self-induced and collector-induced flotation. The effects of galvanic interactions among different minerals and grinding media on flotation are summarized.
38 citations
TL;DR: In this paper, the efficiency of reduction-roasting/magnetic separation of hematite, goethite and any extremely fine-grained iron ore, which is nonresponsive to conventional processing techniques, is reviewed.
Abstract: The efficiency of reduction-roasting/magnetic separation of hematite, goethite and any extremely finegrained iron ore, which is non-responsive to conventional processing techniques, is reviewed. Roasting equipment, roasting mechanism, superior results over conventional techniques, and certain advantages are highlighted. Previous works on solid state diffusion theory and gas diffusion theory, in the direction of explaining the mechanism of iron ore reduction are indicated. The transformation of hematite to magnetite, wustite, and metallic iron, with a reductant, at elevated temperature, is established by XRD analysis.
34 citations
TL;DR: The sources of arsenic and the various process options for treating arsenical gold ores and concentrates are briefly reviewed in this article, and the problem relating to the removal of arsenic from gaseous emissions from roasting processes is considered.
Abstract: The processing of gold bearing sulphide minerals which contain arsenopyrite and other complex arsenic sulphide minerals results in arsenic containing emissions and effluents which must be given careful consideration in relation to clean air and clean water standards. The sources of arsenic and the various process options for treating arsenical gold ores and concentrates are briefly reviewed The problem relating to the removal of arsenic from gaseous emissions from roasting processes is considered Residues from aqueous processing contain a variety of arsenical materials which have not been characterised, and the long-term stability of these is suspect The use of lime to stabilise aqueous residues as cither calcium arsenate or calcium arsenite has been shown to be inadequate for long term disposal since both compounds are converted into calcium carbonate due to the influence of carbon dioxide in the atmosphere Ferric ion solutions have been used to precipitate ferric arsenate or to form ferric hydr...
31 citations
TL;DR: In this paper, the preparation of elemental boron by fused salt electrowinning from KCI-KF-KBF4 electrolyte and electro extraction from soluble B4C anodes in NaCI-KFs-KBFs melt have been investigated, and the influence of process parameters such as bath composition, temperature and current density on the quality and yield of the electrodeposited born have been studied.
Abstract: The preparation of elemental boron by fused salt electrowinning from KCI-KF-KBF4 electrolyte and electro extraction from soluble B4C anodes in NaCI-KF-KBF4 melt have been investigated. The influence of process parameters such as bath composition, temperature and current density on the quality and yield of the electrodeposited born have been studied.
25 citations
TL;DR: In this article, the basic nature of flow and the measurement techniques are analyzed and a detailed discussion is presented on the empirical, semi-empirical and the Navier-Stokes equation based flow models available in the literature.
Abstract: A critical assessment is presented for the existing fluid flow models and the flow measurement techniques used for hydrocyclone classifiers. The basic nature of flow and the measurement techniques are analyzed and a detailed discussion is presented on the empirical, semi-empirical and the Navier-Stokes equation based flow models available in the literature. The existing equations describing turbulence and pressure drop are also critically reviewed.
24 citations
TL;DR: In this paper, the DEHPA flowsheet has been tested at bench-scale to produce several kilograms of 93% Y2O3 in the aqueous phase, and the flowsheet based on the solvent was confirmed at pilot-plant level.
Abstract: A rare earth concentrate assaying about 60% Y2O3, is generally obtained directly from Y rich minerals like xenotime or from monazite after preliminary fractionation of rare earths chloride as is practised currently at Indian Rare Earths Ltd.. Alwaye. Using this intermediate concentrate. SX process has been developed in our laboratory to purify Y (>99.9%) in presence of NH4SCN. The process parameters for DEHPA and PC 88A systems have been optimised using a computer program in BASIC. The DEHPA flowsheet has been tested at bench-scale to produce several kilograms of 93% Y2O3. During these trials certain problems were faced due to high acidities. With PC 88A there were no problems and the flowsheet based on the solvent was confirmed at pilot-plant level. The solution containing 93% pure Y2O3, is purified further by another cycle of SX with 50% TBP in kerosene in presence of 1.0 M NH4 SCN. The impurities are extracted leaving >99.9% pure Y2O3 in the aqueous phase. The process parameters optimised for obtaining...
24 citations
TL;DR: In this paper, the authors reported work carried out to process 2 million tons of copper slag for recovery of cobalt and copper in the northern part of Turkey from ancient time.
Abstract: An approximate amount of 2 million tons of copper slag has been lying on the northern part of Turkey from ancient time. This slag contains 0.43% cobalt and 1% copper. This paper reports work carried out to process this slag for recovery of cobalt and copper.
21 citations
TL;DR: In this paper, the wear properties of cast iron media materials during dry and wet grinding conditions are discussed, giving special importance to the corrosion and abrasion properties of media materials.
Abstract: Cast iron balls have been used for decades as a grinding media in all types of grinding applications. Early applications of cast iron grinding balls in mineral processing operations were disastrous due to spalling and premature breakage. Better control and understanding of a high chromium cast iron metallurgical system have led to the use of high chromium cast iron balls in all types of grinding. This paper reviews the wear properties of cast iron grinding media materials during dry and wet grinding conditions. The media wear mechanisms and the factors influencing the grinding ball wear during grinding are discussed, giving special importance to the corrosion and abrasion properties of cast iron media materials.
17 citations
TL;DR: In this article, the leaching of chalcocite (Cu2S) and copper-lead matte in oxygenated acidic chloride-sulphate leachants at 85°C was studied.
Abstract: The leaching of chalcocite (Cu2S) and copper-lead matte in oxygenated acidic chloride-sulphate leachants at 85°C has been studied. Copper leaches from both materials via a two stage process, the overall reactions being and The chloride ions are believed to promote the formation of a crystalline porous sulphur layer on the reacting particle so that essentially complete copper extraction is possible. The same mechanism is also believed to apply during the leaching of copper iron matte and white metal. During the leaching of the copper lead matte, the galena reacts first by galvanically protecting the chalcocite in the duplex structure forming lead sulphate and elemental sulphur. The overall reaction is:
TL;DR: In this paper, the progress made to date for processing copper oxide and sulfide ores through the application of solvent extraction-electrowinning (SX-EW) process technology is reviewed.
Abstract: This paper reviews the progress made to date for processing copper oxide and sulfide ores through the application of Solvent Extraction-Electrowinning (SX-EW) process technology. SX-EW Kchnology is a two step process. First, the metal in the pregnant (leach) solution is extracted using an organic reagent (solvent) and stripped from the solvent in a purified state using concentrated acid. Second, the metal is recovered from the acid solution as high purity cathode copper by electrowinning. Since the introduction of SX-EW technology in 1968, new generations of extractants with better copper selectivity, faster kinetics, better settling characteristics, and reduced crud formation have been developed by major reagent producers, Design improvements in mixer-settlers and electrovinning cells have also been introduced. Davy McKee’s combined mixer-settler, Krebs conical pump mixer and superimposed launders, high efficiency mixer impellers. MIM’s ISA process stainless suel cathode blanks, and automated stripping m...
TL;DR: In this article, it was shown that 80% of the world production of chromite will be finer than 10 mm and to obtain products of specific quality concentration processes, the agglomeration of the fine concentrate will be necessary for the ferrochromium plant.
Abstract: Chromite. being one of the most important minerals in the metallurgical, chemical and refractory industries, is the only mineral from which chromium metal can be economically produced. As a result of the fast depletion of high grade lump ores, in the coming years 80% of the world production of chromite will be finer than 10 mm and to obtain products of specific quality concentration processes will be inevitable. Taking into account the difficulty in obtaining lump ores, the agglomeration of the fine concentrate will be necessary for the ferrochromium plant.
TL;DR: The use of autotrophic and heterotrophic microorganisms in the solublisation of gold from refractory sulphides and oxide ores is discussed in this article.
Abstract: The use of autotrophic and heterotrophic microorganisms in the solublisation of gold from refractory sulphides and oxide ores is discussed. Basic microbiological characteristics of the leaching bacteria are outlined. Reaction mechanisms in the biooxidation of gold-bearing arscnopyrite and pyrite an: illustrated with special reference of Thiobacillus ferrooxidans. Biological and engineering factors influencing biooxidation for the liberation of gold are critically examined. Available reactor designs as welt as pilot-plant operations are brought out. The utility of heterotrophs in the direct leaching of gold is also evaluated. The role of biosorption in the recovery of precious metals from solutions and in environmental control is also examined. The potential of biomineral technology for processing gold-bearing ores and concentrates in the Indian context is highlighted.
TL;DR: In this article, the chemistry of pre-calcination and reduction roast processes with H2 + H2O gaseous mixture was analyzed, in order to find the best nickel and cobalt recoveries after selective roasting of nickelferrous laterites.
Abstract: The chemistry of pre-calcination and reduction roast processes with H2 + H2O gaseous mixture was analyzed, in order to find the best nickel and cobalt recoveries after selective roasting of nickelferrous laterites A thermodynamic analysis of the pre-reduction of garnieritic ores aiming NiO and CoO reduction showed that the low NiO activity in the ore demands highly aggressive reducing conditions to attain reasonable nickel recoveries. Between 650-850°C, the highest nickel recoveries through amoniacal leaching was obtained at 750°C with 60% H2 + 40% H20. Tests at 900°C revealed an unexpected high nickel recovery probably due to the presence of metallic iron which acted as a solvent for metallic nickel, favoring in consequence its metallization.
TL;DR: In this article, the results of experimental investigations carried out for developing a flowsheet for the treatment of Niobium-tantalum bearing cassiterite containing about 23% of mixed niobium and tantalum oxide were presented.
Abstract: The paper presents the results of experimental investigations carried out for developing a flowsheet for the treatment of niobium-tantalum bearing cassiterite containing about 23%of mixed niobium and tantalum oxide. Three different approaches viz. direct smelting of cassiterite to tin metal and niobium-tantalum bearing slag, reduction roasting-acid leaching and alkali fusion-leaching to separate tin from niobium-tantalum followed by recovery of tin as oxide and finally carbothcrmic reduction to tin metal have been examined on laboratory scale. It has been observed that alkali fusion—leaching—tin oxide smelting is quite attractive to obtain a good purity tin metal and also recover niobium and tantalum as mixed oxides.
TL;DR: In this paper, the potentials, galvanic currents, and mixed potentials of chalcopyrite-galena and sphalerite-sphalerite were measured.
Abstract: Sulphide minerals are semiconductors, and galvanic couples form once the minerals come in contact in aqueous medium. These galvanic effects play an important role during wet grinding, flotation and leaching. In this paper, the literature on this field has been reviewed. Such interactions have been examined in the present study of ammonia leaching of Cu, Pb. Zn sulphide minerals through dual cell measurements. Detailed measurements on three such galvanic couples, viz.. chalcopyrite-galena, chal-copyrite-sphalerite, and sphalerite-galena are reported. Individual half cell potentials, galvanic currents, and mixed potentials have been measured. Tafel plots for the chalcopyrite-galena couple have also been determined. Studies have been made to obtain a qualitative as well as a quantitative estimation of possible galvanic interactions. The estimations are compared to some of the actual leaching results.
TL;DR: In this article, the chemistry involved with the leaching of gold by acidic thiourea solutions has been reviewed, and the thermodynamics and kinetics of the complexation of thourea with gold, silver and other associated metals, as well as the degradation of the thourerea itself were discussed.
Abstract: In this paper, the chemistry involved with the leaching of gold by acidic thiourea solutions has been reviewed. The thermodynamics and kinetics of the complexation of thiourea with gold, silver and other associated metals, as well as the degradation of the thiourea itself were discussed. Some of the relevant technical aspects of thiourea leaching were considered. The available data were analyszcd in order to establish the rate determining step for gold dissolution process and the dependence of thiourea consumption on leaching conditions.
TL;DR: In this paper, a review examines the progress which has been made in understanding the chemical reactions and the microstructural changes which occur during the decomposition of solids, and the relationships between reaction mechanisms, the product microstructures and kinetics are explained.
Abstract: This review examines the progress which has been made in understanding the chemical reactions and the microstructural changes which occur during the decomposition of solids. A number of common product morphologies are described, and the relationships between reaction mechanisms, the product microstructures and kinetics are explained. From the analysis of a number of systems it is argued that changes in product morphology take place when changes occur in the relative rates of the chemical reactions and mass transport processes on or in the product or original solids. The factors affecting these transitions and ways of control ling product microstructure are discussed.
TL;DR: In this article, the physical process of gas evolution viz nucleation, growth and detachment are discussed and the dynamic process of electrogeneration of gas bubbles as affected by the interaction amongst a large number of process variables has been dealt with in detail.
Abstract: Electrolytic gas evolution plays a very significant part in a number of electrochemical processes. In the electrowinning of metals the evolution of gases at the electrodes is a very important phenonenon. Gas evolution is common in chlorine and water electrolysis and in a number of other processes. Electro-generated gas bubbles have been used in the treatment of waste water and considerable amount of work has been done on the electroflotation of mineral fines which are unsuited for treatment by conventional flotation techniques. The physical process of gas evolution viz nucleation, growth and detachment are discussed. The dynamic process of electrogeneration of gas bubbles as affected by the interaction amongst a large number of process variables has been dealt with in detail. Flotation of mineral fines as affected by the size and charge of the bubbles is also discussed.
TL;DR: In this paper, a greal deal of effort has been directed towards the development of economically and technically feasible processes for the chemical oxidation of iron sulfides, such as roasting, and sulfate-, nitrate-, chloride-and alkaline-based aqueous oxidation processes.
Abstract: A greal deal of effort has been directed towards the development of economically and technically feasible processes for the chemical oxidation of iron sulfides. Such processes applied commercially or under active development, including roasting, and sulfate-, nitrate-, chloride- and alkaline-based aqueous oxidation processes, are outlined in this paper.
TL;DR: In this paper, the production of various borates in Turkey is briefly highlighted with particular emphasis on the current processing technology employed, and the authors highlight that Turkey has the largest share of known reserves of boron minerals in the world, and comes second after USA in terms of production.
Abstract: Turkey has the largest share of known reserves of boron minerals in the world, and comes second after USA in terms of production. This makes her a very important supplier of various borates widely used in industries from glass making to detergents, from herbicides to fertilizers. In this paper, the production of various borates in Turkey is briefly highlighted with particular emphasis on the current processing technology employed.
TL;DR: In this article, the CSIRO process was used to produce high purity (99.9% ZrO2) powder suitable for structural and electronic applications, and a detailed description of the process was given.
Abstract: Zirconia ceramics possess an impressive combination of properties which enable them to compete with metals and alloys in many applications where high temperature performance and erosion and corrosion resistance are required. In order to produce zirconia ceramics for industrial applications, it is vital to produce zirconia powders of high purity, controlled particle size, morphology and surface area and weak agglomerate strength, Various methods for the production of zirconia powders have been proposed and these are described in the paper. The paper also includes a detailed description of the CSIRO process which produces high purity (99.9% ZrO2) powder suitable for structural and electronic applications.
TL;DR: In this article, an empirical mathematical model has been developed for the simulation of an integrated solvent extraction circuit consisting of an extractor, scrubber and a stripper, which can be used to simulate the separation of any lanthanide from a mixed linthanide feed.
Abstract: An empirical mathematical model has been developed for the simulation of an integrated solvent extraction circuit consisting of an extractor, scrubber and a stripper. This model is designed to simulate the separation of any lanthanide from a mixed lanthanide feed. The Kremser equation is used to calculate the separation occurring in each section of the circuit. The inputs required for the simulation are the feed composition, separation factors, equilibrium data of the key element under a wide range of conditions, the number of stages and flow rates of the aqueous and organic streams in the circuit. This model has been validated with the experimental data for the separation of Nd from a mixed lanthanide chloride feed with 2-ethylhexyl phosphonic acid mono 2-ethyl-hexyl ester (EHPNA) as an extractant.
TL;DR: In this article, the effect of oxidation on flotation and wetting behavior of chalcopyrite samples was investigated using galvanostaiic polarization, cyclic voltammetry and impedance spectroscopy.
Abstract: This paper reports on electrochemical investigations involving several techniques such as galvanostaiic polarization, cyclic voltammetry and impedance spectroscopy to delermine the effect of oxidation on flotation and wetting behaviour of four different chalcopyrite samples, one from South Africa(obtained through Ward's, New York) and three from India, namely Malanjkhand (fresh), MalanjUhand (tarnished) and Alminrock.
TL;DR: The reactive and refractory metals zirconium, titanium, tantalum and niobium have been in commercial production and industrial application over the last 30 years and more as discussed by the authors.
Abstract: The reactive and refractory metals zirconium, titanium, tantalum and niobium have been in commercial production and industrial application over the last 30 years and more. With growing experience, there has been progressive improvement in process and equipment designs in the industrial practice. There has also been a continuous drive to develop entirely new processes, and to diversify the applications of these metals. The paper reviews the present status and the emerging trends, and places the Indian work in the global perspective.
TL;DR: In this article, the effects of common metallic and LIX64 organic solvent impurities on nickel electrodeposition have been investigated for an economical and viable process development for different raw materials.
Abstract: The effects of common metallic and LIX64 organic solvent impurities on nickel electrodeposition have been investigated for an economical and viable process development for different raw materials. Variations of bath pH. temperature and current density at different LIX64N concentration were studied to observe the effects on current efficiency, physical appearance of the deposit, deposit contamination, crystallographic orientation intensities and deposit morphology.
TL;DR: In this article, it was found from the oxygen potential in matte and slag in the settler that most of the smelting reactions are completed in the reaction shaft or just beneath the shaft.
Abstract: Research activities on the smelting reaction in the Outokumpu flash furnace and its operation have been reviewed. First, the oxidation kinetics of copper concentrate particles and the ignition phenomena were discussed. Second, the mathematical modeling and experimental investigation on the progress of smelting reactions in the shaft of the furnace were summarized. Dust generation and behavior of minor elements in the shaft were also important. Third, it was found from the oxygen potential in matte and slag in the settler that most of the smelting reactions are completed in the reaction shaft or in the settler just beneath the shaft. The use of powder coke results in the formation of reduction atmosphere on the slag surface in the settler, and its effect on the operation was discussed. The residence time distribution of slag in the settler is also an important factor of the operation of the flash smelting furnace.
TL;DR: In this article, the authors compared the thermodynamic behavior of rare earth metals lanthanum and cerium in liquid and steel as predicted by the high temperature (1400-1600°C) thermochemistry of oxides, oxysulphides and sulphides.
Abstract: The thermodynamic behavior of the rare earth metals lanthanum and cerium in liquid and steel as predicted by the high temperature (1400-1600°C) thermochemistry of their oxides, oxysulphides and sulphides, is compared to experimentally-determined thermodynamic behavior reported in the literature. The comparison of experimental results includes data from high temperature equilibrium studies and electrochemical cells. Phase stability diagrams, constructed in terms of the Henrian activities of oxygen and sulphur, are used to compare thermodynamic data bases and to determine some of the applications of lanthanum and cerium in ferrous metallurgy. M-S-O (M-Ce, La. Ca and Mg) phase stability diagrams arc used in the comparison of hot-metal desulphurization processes, and the control of graphite morphology in the production of nodular and compacted graphite iron.
TL;DR: A review of the application of peroxygnn reagents in hydrometallurgical processes can be found in this article, where hydrogen peroxide, H202, Caro's acid, H2MS05, and calcium peroxide CaO2 are discussed.
Abstract: The paper reviews development made over the past decade in the application of peroxygnn reagents in hydrometallurgical processes. The reagents are hydrogen peroxide, H202, Caro’s acid, H2MS05, and calcium peroxide, CaO2. Their chemical properties and methods for on-site storage or production are outlined. Most progress has been made in the gold extraction industry, where hydrogen peroxide and calcium peroxide have been used to enhance oxygen availability in the cyanide leaching of gold ores, in both agitated and heap leach systems. Properly controlled, the use of these reagents can lead to increased rates of gold extraction and savings in cyanide consumption. Hydrogen peroxide is also widely applied for the oxidative destruction of cyanide in gold mill effluent solutions and tailings ponds. Caro’s acid can also be used for this purpose, with advantage in certain situations, which arc discussed. Caro’s acid has found industrial application in the leaching of uranium ores in Australia at the Nabarlek mine a...