Search Documents

By E. Kuzeci, R. Kammel

"Lately various voltametric methods have gained increased attention as an analytic tool in hydrometallurgy. Voltammograms with mercury drop electrodes or glassy carbon electrodes provide information about the electrocrystallization of cathodic deposits and allow calculation of kinetic data by means of characteristic parameters like the peak potential and peak current and their variation with the voltage scanning rate.Cyclic voltammograms are also suitable for identification of reaction sequences. Voltammograms with carbon paste electroactive electrodes containing metal sulphide additions reveal information about the dissolution behavior. The stripping voltammetry can be applied to analyze metal ions and organic additives (e. g., thiourea) in extreme low concentration. Typical application of the various methods studied with microcomputer controlled measurement system are explained by examples selected from copper hydrometallurgy.IntroductionThe use of electroanalytical methods in metallurgical process control can be dated back to the starting period of industrial copper refining, when the deposition of the metal ions was followed electro-gravimetrically by weighing the electrode with deposits (1). The principles of metal deposition and dissolution have not changed but the methods to follow these phenomena were subjected to noticeable developments and especially the introduction of polarographic investigations by Heyrowsky (2) has greatly contributed to the progress in electro-analysis. A review about the fundamental work on the electrochemical kinetics in earlier time is compiled in a monograph of Vetter (2). With the steady improvements in the instrumental techniques, it is nowadays possible to apply several current and potential modulations for measurements with improved selectivity and sensibility. There is however, still a lack in theoretical interpretation of the data obtained. More theoretical information are already available for linear voltametric methods for systems where reduced as well as oxidized species are dissolved in the electrolyte (4, 5). Some recent investigations have also shown the reliability of these techniques to study electro-crystallization (6, 7). Main fields of the application in the hydro - and electro-metallurgy are:"

Jan 1, 1989

By Howbert Van Dyne

THE Presidio mine of The American Metal Co. is situated in the "Big Bend" region, some 45 miles over state highway south of Marfa, a station on the Southern Pacific R.R. It lies 20 miles by road north of the Mexican border, in semidesert surroundings typical of this general section of the United States and the adjoining part of Mexico. All supplies are hauled in by truck from Marfa under contract. The concentrates and precipitates produced by the mill are carried by the same trucks to Marfa, from whence they are shipped, respectively, to the El Paso and Selby plants.

Jan 1, 1930

By G. Sedelnikova, D. Kim, N. Ibragimova

"The object of this study was three samples of sulfide old tailings, which were obtained after Cu- Zn ores processing. Fine metal dissemination in sulfides as well as fine mineral intergrowth determine the refractory nature of material and low metal extraction using simple methods: gravitation 1-6%, flotation 32-48%, cyanidation 10-37%, and cause the need to use sulfide bio-oxidation to liberate gold and to recover it by heap leaching. The gold is the main valuable metal in the tailings with content 1-1.5 g/t. Heap bio-oxidation with mesophilic and moderately thermophilic bacteria was used for pre-treatment of tailings before gold heap leaching from bio-oxidation solid residues. The tailings have a low permeability < 0.3-1.2 m/day, which is caused by migration of fine particles, decreases recovery rates, and is poorly suited to heap bacterial leaching. Therefore, preliminary gold sulfide tailings with permeability < 0.3 m/day were pelletized using copper containing flotation tailings of converter slags and calcium oxide. The most gold extraction was obtained for pelletized tailings. The base metals (copper and zinc) were precipitated from bacterial solutions. Experiments have demonstrated effective bio-oxidation of all third gold sulfide tailings samples and enough high gold extraction 60-82%.INTRODUCTIONIn Russia, as everywhere, there is a trend toward deterioration in the quality of mineral resources, including non-ferrous and precious metals, manifested in lower grade and higher complexity of ores. The proportion of refractory ores is increasing, characterized by fine dissemination of metals in sulfides, intergrowth, and poor liberation of minerals during concentration, resulting in loss of base and precious metals to flotation tailings.Over the operation period, huge reserves (hundreds of million tons) of ore processing waste have been accumulated at mining and concentration operations. Because of the imperfections of the previously used ore concentration technologies, the content of precious and base metals in flotation tailings is comparable with the grades of the ores being currently processed. Therefore, old tailings can be viewed as an additional reserve of non-ferrous and precious metals. The works (DEN, 1997; Lyman, Johnson, & Guerney, 2000) demonstrate that, tailings containing sulfides (sulfur, copper, zinc, and other metals) are a potential environmental hazard since they produce acid drainage water containing toxic components. Processing those tailings would require designing an effective technology for recovering useful components and protecting the environment."

Jan 1, 2016

By W. A. Lang

"I.-IntroductionAn attempt bas been made in this paper to provide a basis for appraisal of the future of the coal briquetting industry in Alberta by outlining the processes used for briquetting various ranks of coal, by specifying the requirements of a briquetted fuel, by indicating .the status of the industry in the United States, by giving developments in Western Canada, by assessing costs of processing, and by discussing briquetting researches in progress. Much of .the detail bas been omitted since this might mask, rather than reveal, the more important phases of the problem. Reference will be made when possible to published articles where many of the details can be obtained.It should be stated at the outset that, in the writer’s opinion, there are three possible developments in Alberta as regards briquetting: (a) an expansion of the briquetting of the fines of • non-coking and coking coals of semi-anthracite, and of low and medium volatile bituminous rank; (b) the processing of the fines of high-volatile C bituminous coals; and (c) the upgrading of the lower rank high-moisture sub-bituminous coals. Details of the chemical and physical properties of these coals can be obtained in publications of the Research Council of Alberta (1, 2), and of the Fuel Research Station, Bureau of Mines, Ottawa (3).Semi-anthracite and low and medium volatile bituminons coals occur in the mountain areas of Alberta, where, during the upthrust of the Rocky mountains, the coal beds served as the sliding surface. This resulted in the coals being; crushed and consequently they contain a h1gh percentage of fines. In some cases they are high in mineral matter and require to be cleaned before being processed. However, the cleaning of fine coal is both difficult and costly. Both the amount of fines present in the mine-run coal and the amount of mineral matter associated with the coal have increased through the introduction of mechanized mining and through the recovery of coal by stripping operations."

Jan 1, 1950

By Z Terzic, M Schult, D Chu, S Macklin

The East West Link road tunnels are proposed to provide a connection between the CityLink toll road and the Eastern Freeway north of the Melbourne CBD. The alignment passes from Moonee Ponds valley beneath the Upfield Line railway cutting, Royal Park, the historic Melbourne Cemetery and beneath Alexander Parade rising to an eastern portal at Hoddle Street. The western (Royal Park) part of the alignment passes through the folded and faulted Silurian Melbourne Formation, which has been subjected to deep weathering since the Triassic.The Melbourne Formation in the Royal Park area is mainly characterised by interbedded sequences of siltstone and fine-grained sandstone. The beds are often graded and a clear boundary between the siltstone and fine-grained sandstone rock can be difficult to distinguish. Variation in lithology and the presence of structural geological features such as folds and faults have resulted in an irregular weathering profile within the Silurian rock; nonetheless the formation typically becomes less weathered with depth.Due to difficulties in obtaining reliable laboratory strength and stiffness relationships with weathering grade, in situ testing methods such as downhole shear wave velocity and high-quality pressuremeter testing are a useful aid to assessing appropriate geotechnical parameters for design.This paper presents an analysis of the variation in shear modulus of the Melbourne Formation, determined at small-strain (from downhole seismic data) and at ‘engineering scale’ strain (from pressuremeter tests) for extremely weathered (XW), highly weathered (HW) and moderately weathered (MW) rock. Estimates of small strain shear modulus (Go) obtained a range between 400 to 3400 MPa for these weathering grades. By comparison against the pressuremeter test data, reduction factors to be applied to these Go values to estimate shear moduli at engineering strain levels typically range between 0.10 and 0.35.The downhole geophysics undertaken in the Royal Park boreholes also suggests that there is an inversion in velocity between approximately 15 and 27?m depth below the top of the formation. This is thought to be related to the effects deep Plio-Pleistocene weathering, iron cementation of joints and increasing frequency of ‘non-healed’ joints in the transition from MW to slightly weathered (SW) rock.CITATION:Macklin, S, Schult, M, Terzic, Z and Chu, D, 2014. Strain-dependent stiffness of the weathered Melbourne Formation, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 179–188 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By M. F. El-Demerdash

The activity distribution diagrams for different species in aqueous systems are developed. Computational method may be considered as an extension of the Activity-Term method introduced by the authors to construct EH-pH diagrams. In the Activity-Term method, all activities of different species are evaluated before deciding the most stable one. In the present study, a factor is assumed to allow for the conservation of the element. At any point, the total concentration of all species should contain only the input m moles of the element (elements) considered. This approach is applied to Zn-, 5-, and Zn-S-H2O and activity distribution diagrams are plotted as a function of pH, at different potential levels and at different temperatures.

Jan 1, 1990

By K. F. Unrug

The research work reported in in this paper deals with the monitoring of roof behavior in a drift mine located in Eastern Kentucky operating in the Coalburg Seam. The thickness of the seam at the monitoring site ranges between 9 and 10 feet with the immediate roof changing from sandstone to shale then back to sandstone. Shale thickness varies between 0 and 2.5 feet. The characteristics of the immediate shaly roof were monitored with 38 dynamometers which were set up in three survey lines to cover the entire range of shale distribution. The dynamometers are capable of providing accurate load readings in the range of +/- 5 pounds. To closely observe the contribution of moisture toward roof deterioration the dynamometers were set up in intake and neutral airways. A television borescoping camera was used in conjunction with the dynamo- metric instrumentations at pre- determined observation holes to physically observe and record the separation process of the shale and sandstone stratum with respect to time. Monitoring took place between January 1985 through January 1986 in order to cover a full cycle of dry and wet mine conditions associated with the seasonal changes. Analysis of the data show a trend of roof deterioration induced by condensation and eventual penetration of moisture within the immediate roof bedding planes, leading to rapid disintegration of the mine roof.

Jan 1, 1986

By G. Akdogan, S. M. Bradshaw, M. I. Isaacs, P. Van Wyk

In the mineral processing industry, Ni-Cu-Fe-S converter matte is leached in order to remove base metals from a concentrate containing platinum group metals (PGMs). This paper investigates the atmospheric leaching process, in order to develop a better understanding of the leaching behaviour of the base metals; in particular Cu, Fe, Ni, and the PGMs in particular Ru and Ir with key process variables, acid concentration, copper concentration under oxidative leaching conditions. Higher initial acid concentration resulted in a higher copper, iron and nickel extractions, as well as higher leaching rates together with faster Cu, Ru, Ir precipitation occurring. On the other hand, a higher initial copper concentration resulted in more nickel but less iron being extracted. Keywords: PGM, converter matte, leaching, precipitation

Jan 1, 2020

By G. D. Hibbard

New regions of material property space can be accessed by combining microstructural design at the nm-scale with architectural design at the µm- or mm-scale. In the first case, large strength increases associated with grain size reduction to below 50 nm have driven extensive research efforts into the development of nanocrystalline materials [e.g. 1-3]. For many potential structural applications, however, the density of a nanocrystalline material is just as important as its strength. In fact, reducing the density is more important than increasing the strength for certain weight specific materials performance indices, and it is especially critical for applying structural nanomaterials in the aerospace and automotive sectors. We have developed a new type of structural nanomaterial wherein the effective density of the parent metal is reduced by more than an order of magnitude by incorporating an internal periodic cellular architecture of open space. In one example a low density cellular nanocrystalline material was created by electroforming nanocrystalline Ni around a rapid-prototyped acrylic photopolymer microtruss, Figure 1 [4]. Microtruss materials have periodic cellular architectures that are specifically designed to undergo stretching-dominated deformation as opposed to the bending-dominated deformation in conventional open cell metal foams [5,6]. This new cellular nanocrystalline hybrid material combined the structural efficiency of microtruss architectures with the ultra-high strength that can be achieved by grain size reduction to the nm-scale. Although it played a critical role as a cathode support during the initial stages of nanocrystalline electrodeposition, the polymer core did not contribute significantly to the inelastic buckling resistance of the composite metal/polymer struts and it may therefore be desirable to remove it post deposition by means of chemical dissolution or thermal decomposition [4]. Nanocrystalline electrodeposition can also be used to reinforce conventional cellular metals (Figure 2), creating new types of cellular composites such as metal/metal microtruss hybrids [7-10] and metal/metal foam hybrids [11,12]. For example, nanocrystalline Ni-Fe alloy sleeve thicknesses of up to 400 µm were used to reinforce an aluminum alloy microtruss that had been fabricated using a stretch-bend approach; the nanocrystalline sleeves had the effect of increasing the microtruss strength by up to a factor of twelve and the specific strength by a factor of three [8]. Alternatively, much thinner sleeves can be electroplated to produce structural coatings. In one example, a nanocrystalline Ni coating was designed to provide both corrosion protection and inelastic buckling resistance [10]. Because the ultra-high strength material was optimally located at the furthest distance from the neutral bending axis, only a thin coating of 50 µm was needed to double the inelastic buckling resistance of the 1.13 mm x 0.63 mm cross-section plain carbon steel struts [10]. Overall, the mechanical performance increase that can be obtained through electrodeposition depends on a complex interaction between the starting cellular architecture and the nanocrystalline sleeves.

Jan 1, 2010

By J. J. Sense

10.2-1. Equipment Scheduling. In any earth-moving operation, more profit may be earned or lost by equipment scheduling than by any other single facet of the project. Many now-defunct earth movers would have survived the cost-profit squeeze had they followed an efficient, cost saving, equipment scheduling program. The ideal program would have every item of the equipment fleet working all of the time. In practice for many obvious reasons, principally mechanical conditions, operating conditions, and human nature-this ideal situation is not possible. The cost-conscious organization strives to keep as many pieces of equipment of the fleet working efficiently as much of the work day as possible. Operating efficiency requires the minimum equipment to move the predetermined tonnages in the prescribed period of time. In the case of a shovel-truck operation this would mean the scheduling of the minimum shovel and truck shifts to excavate and transport the necessary tonnage to the processing plant or waste dump. To accomplish this goal, the operator must work from the predetermined production established by the requirements of the plant, stripping ratio, mine plan, etc. This production schedule may be in terms of tons or yards per year, per month, or per hour, but must eventually be translated into tons or yards per ma- chine per unit of time. In this regard, the reader is referred to Sections 8.0, Excavation and Loading, and 9.0, Haulage and Transportation. The trend to larger and faster, and as a result more costly, equipment requires that the operator consider every possibility to keep the equipment operating around the clock, seven days per week. In some areas seven day operation may not be feasible economically, because of premium pay for Sunday work. Mine labor agreements are generally written without premium pay penalties for weekend work, and such scheduling is possible and most often desirable.

Jan 1, 1968

By A. E. Stewart

Slope design in an open pit mine includes determining bench height, bench face angle and berm width. Case histories are presented of two highwall slopes (160 and 220 m or 525 and 720 ft high) excavated in dipping strata in an op¬erating coal mine. These examples illustrate the influence that bench face angle can have on the stability of an entire slope. The two highwall slopes, the lower of which experienced significant instability, were excavated in approximately the same lithologic and structural environment. The main differences between the slopes were the angle at which the bench faces were excavated and the excavating methods that were used. Relevent aspects are also described of the engineering geology, slope design and excavation procedures.

Jan 1, 1998

By R. Noorani, M. Cai

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

Jan 1, 2015

By Getúlio da Silva Abreu

O objetivo geral foi produzir e caracterizar a microestrutura de um compósito abrasivo nanoestruturado no sistema D-Si, via sinterização cíclica de alta pressão e alta temperatura (HPHT). A sinterização cíclica em alta pressão e alta temperatura de compósitos foi feita a partir de uma mistura de 70% diamante e 30% de Si como ligante, o qual foi moído por moagem de alta energia sendo então partícula nanométricaso. A sinterização foi realizada por 1 a 4 ciclos de pressão (P) de 7GPa- 4GPa e temperatura (T) 1600°C-300°C, para um tempo (t) de 1min. As análises de difrações de raios X mostraram a ocorrência, além do diamante, de SiC, FeSi e grafite. As análises de MEV e EDS mostraram uma distribuição uniforme dos cristais de diamante na matriz de SiC. A análise da região de fratura das amostras mostrou que todos os cristais de diamante foram abrangidos pelo ligante, ou seja, a liga formada a partir da interação de carbono e de silício. Finalmente, conclui-se que esta pesquisa aprimorou a técnica de produção de MCDs para uso futuro em bits de brocas de perfuração de poços de petróleo.

Aug 16, 2017

By S. Pearson, L. Rotherham

Measurements have been made of the variation of internal friction with temperature for OFHC copper, and for a series of binary solid solutions of high purity copper with zinc, gallium, germanium, arsenic, and silicon, to investigate the effect of alloying elements in substitutional solid solution on grain boundary viscosity. The apparatus used was of the torsional pendulum type developed by KeI1 modified so that the specimen and vibrating system could be maintained in a high vacuum. The activation energy for grain boundary relaxation in copper is 33,000 cal per mol. This is considerably less than the activation energy for self-diffusion, in disagreement with Ke&apos;s theory2 that the two activation energies should be the same. All the alloying elements increase the activation energy for grain boundary relaxation to approximately 44,000 cal per mol, increasing the grain boundary viscosity at a given temperature. The results are discussed in terms of theories of grain boundary slip put forward by MottQ and by Ke.+ Experiments have also been made to investigate the effect of small amounts of oxygen on the variation of internal friction with temperature for copper. EXPERIMENTS described in this paper were designed to investigate the effect of alloying elements in substitutional solid solution on grain boundary viscosity, using the internal friction method developed by Kel for measuring grain boundary viscosity. It was considered desirable to make the system under investigation as simple as possible by making experiments on a comprehensive series of binary alloys of copper with the elements immediately following it in the periodic table, i.e., zinc, gallium, germanium, and arsenic. These elements are within the range of favorable size factor for solution in copper, and the systems have been extensively investigated by Hume-Rothery and his co-workers." Later, in order to study the effect of the relative size of the solvent and solute atoms, experiments were made on a series of Cu-Si alloys, since the apparent atomic diameter of silicon when in solution in copper—the diameter necessary to assign to the solute atoms to account for the lattice constant of the solid solutiona—is almost the same as that of the solvent atoms. Preliminary experiments were made to measure the variation of internal friction with temperature for pure copper. Ke made some experiments on copper," but found that the curves obtained were not reproducible in consecutive experiments. The copper was maintained in an argon atmosphere during the experiments but, although he took precautions to exclude oxygen, Ke came to the conclusion that the precautions were not entirely satisfactory, and that the lack of reproducibility must be due to absorption of oxygen by the copper. Experiments have therefore been made to investigate the effect of small amounts of oxygen on the variation of internal friction with temperature for copper. Previous Work Ke made extensive experiments on high purity aluminum and was able to show that the grain boundaries behave viscously at high temperatures. He found that the relative rate of movement of the grains could be expressed as Where v is the velocity of slip, A is the constant, u is the shear stress, H is the activation energy, R is the gas constant, and T is the absolute temperature. By assuming that the boundary layer was one atom thick, he obtained a value for the viscosity which, when extrapolated to the melting point, gave good agreement with the viscosity of the liquid metal at the melting point. Ke also made experiments on other high purity and commercial purity metals:, and on some alloys." " He came to the conclusion2 that the activation energy for grain boundary slip was the same as for self or volume diffusion and for steady state creep in single crystals. Rotherham, Smith, and Greenough" have shown recently that the activation energy for grain boundary slip is not the same as for self-diffusion in tin,

Jan 1, 1957

By A. E. Zawadzki

A progress report is presented on the development of a process for the removal of sulfur dioxide from flue gases. Catalytic oxidation of the sulfur dioxide in flue gases, with the production of recoverable sulfuric acid, has been demonstrated to be technically feasible. Problems associated with the process are discussed. The need for an inexpensive and efficient process for controlling sulfur dioxide emissions from utility plant stacks has been accentuated by the ever-increasing public demand for elimination of all man-made air pollutants. I would like to describe the results of an investigation of the development of such a process; more important, I would like to present a discussion of the problems associated with the process which remain to be solved. The research work on the BCR catalytic gas phase oxidation process has been jointly sponsored by the Association of Edison Illuminating Cos., Edison Electric Inst. and Bituminous Coal Research, Inc., since 1958. However, work on SO2-pollution abatement was initiated by BCR in 1953. Tieman and Clymer,1 working with ozone and simulated flue gases, evaluated a gas phase oxidation process for removing SO2 from flue gases. Their experimental data indicated that the use of ozone to oxidize SO2 in flue gas concentrations, with subsequent recovery of H2SO4, did not appear to be economical due to the large ratio of ozone to sulfuric acid produced (2.6 to 1). The cost of the ozone would be 6 to 10 times the cost of sulfuric acid produced. As a result of the ozone study, work on a catalytic oxidation process was developed. The following reactions are the basis for the catalytic oxidation process Reaction [I] normally occurs in the combustion of sulfur-bearing fuels. At the high temperature found in the combustion chamber, 95% to 99% of the sulfur in the fuel is oxidized to SO2 and 1% to 5% is oxidized to SO3. The concentration of SO2 in the combustion gases depends on the combustion efficiency and the quantity of excess air used. A commonly used rule of thumb is 0.1 percent by volume SO2 in the flue gas for each 1% sulfur in the fuel. Reaction [2] proceeds at a wide range of temperatures. The rate of the reaction is rapid above l,000°F; however, the equilibrium conversion drops rapidly above this temperature. 2 Reaction [3] occurs rapidly to completion at temperatures below 400°F; above this temperature some SO3 exists in equilibrium with H2SO4. Complete dissociation of H2SO4 occurs above 650°F.3 The simplicity of the proposed process provided added incentive to the development and evaluation of the various component unit operations. The advantages of the process were considered to be as follows: 1) no raw materials were required, 2) the unit operations were not radically new; and 3) a salable product, sulfuric acid, would be produced. The successful development of the process was contingent upon the solution of several major problems: 1) The development of a catalyst which would provide high catalytic activity at reasonable conditions of gas flow and temperature without causing an unacceptable increase in pressure drop. 2) The development of a high temperature dust collection system to provide clean flue gases to the catalytic reactor. 3) The complete recovery of the sulfuric acid produced in the process; the effluent gas must contain less than 20 ppm by volume of sulfuric acid. As of this date, the complete solution to these problems has not been achieved. EXPERIMENTAL Catalyst Development: The use of platinum and vanadium catalysts for the production of sulfuric acid by the treatment of dry gases containing 5% to 20% by volume sulfur dioxide has been known for many years. The application of the basic idea of catalytic oxidation of sulfur dioxide in flue gas concentrations was

Jan 1, 1965

By Julian Johnson

The effect of changing redox potential (Eh) on the high temperature sulfuric acid leaching of Western Australian dry-land nickel laterite ores has been investigated. In particular, the effect of added reductant (sulfur, sodium sulfite) or oxidant (potassium chromate) on Eh, leaching kinetics, metal extractions, acid utilisation and leach residues has been determined. Three separate ores - nonhonitic ores from Murrin Mumn and Bulong, and limonitic ore from Cawse - were used in the study. Sulfur addition varied from 0 to 7.8 kg/t ore. The total acid loading was kept constant at 430 kg/t (Murrin Murrin ore) and 330 kglt (Cawse ore), whilst acid loading for Bulong ore was varied according to the presence of either reductant or oxidant. The extraction of both nickel and cobalt from limonite ore remained unaffected when small amounts of sulfkr were added, but addition of even small amounts of reductant to nontronitic ore decreased both nickel and cobalt extraction. Increased manganese and iron dissolution were observed as the levels of reductant increased, accompanied by a decrease in chromium dissolution. As the iron dissolution increased, free acidity decreased, with a subsequent decrease in nickel extraction. In contrast, addition of oxidant lead to reduced iron and manganese dissolution and slower extraction of nickel and cobalt. Keywords: Limonite, Nonhonite, Eh, Nickel Extraction

Jan 1, 2004

By Robert T. DeGavre

The $650 million financing for Into Ltd.&apos;s Soroako nickel project is a story worth telling-not only because the project itself represents a significant achievement but also because there are certain important lessons that can be derived from our experience in financing the project. A critical appraisal of the methods and successes in the financing plan is presented in this article, in light of goals which Inco sought to achieve. A technical assessment of the project is not included, since Inco Ltd. has submitted a series of papers on this subject at the International Laterite Symposium as part of the 108th Annual Meeting of AIME in February 1979. Progress in developing and financing the project is encapsulated in the accompanying project factsheet.

Jan 3, 1979

By Y. C. Liu, W. R. Hibbard

An analysis of the relationship between the deformation and recrystallization textures in face-centered-cubic metals is presented. The analysis assumes that orientations of the secondary as well as the primary textures are related to the deformation texture. The effect of alloying elements on the recrystallization texture of copper-base alloys is also discussed. ROTATIONAL relationships based on prior orientations have been used to derive both the primary and secondary recrystallization textures."" This similarity suggests that, if the secondary texture arises from grains formed during primary recrystallization, as proposed by Dunn: and if primary recrystallization derives its lineage from the deformation structure, then the orientations obtained in secondary recrystallization .as well as those obtained in primary recrystallization should be related to the deformation texture. The following discussions are

Jan 1, 1956

By A. S. Rao

In the original roast-leach-electrowin (RLE) circuit at the Chambishi Cobalt Plant, commissioned in 1978, the separation of nickel and zinc from cobalt in aqueous streams was achieved by successive stages of precipitation using lime. However, this technique was not able to meet the increasingly stringent metal quality requirements of customers whilst maintaining acceptable process recoveries. Intensive process development work was carried out and, in July 1988, an ion exchange circuit for nickel removal was commissioned using DOW XFS 4195 resin and for the first time Z.C.C.M. produced high purity cobalt metal containing less than 0.10% nickel. Following further work, a solvent extraction circuit for zinc removal, using DZEHPA, was commissioned in February 1991 in order to enhance cobalt recovery by reducing co-precipitated cobalt losses. This paper outlines the process development, design, commissioning and subsequent operation of these nickel ion exchange and zinc solvent extraction circuits.

Jan 1, 1993

By W. T. Martson

ABSTRACT Sooner or later, every producing mine faces the question of fill. This paper invites consideration of mill tailings as an economical, efficient, and quantitatively adequate source of such fill. Some of the advantages, disadvantages, methods of utilization, and methods of treating mill tailings for sand recovery are covered. ADVANTAGES AND DISADVANTAGES OF SAND FILL DISREGARDING economic com-promise, that material which supports the greatest applied load with the least compression is the best choice for fill. Table I, reproduced from U. S. Bureau of Mines Bulletin 60, is offered as evidence of the adequacy of hydraulically placed sand. Table II gives the results of tests made in an effort to determine the reason for the difference between load hearing qualities of dry-placed and hydraulically-placed sand. From these, it would appear that hydraulic placing gives a denser initial packing, with corresponding higher, and faster development of, load bearing qualities. Assuming this to be true, then if sand from mill tailings can be placed underground economically, it is the superior fill material. Table III summarizes cost data available. The most cursory glance through the available references (2, 5, 6, 7, 8, 9) will show .that the major benefit from the adoption of sand fill is a decrease in the non-productive fill ?cycle of a working place. This, it is estimated, increases the output of an individual stope by from 25 to 50 per cent. The advantage of reducing the number of required working places for a constant daily production is obvious.

Jan 1, 1951