Search Documents

By André Laplante

The mineralogy of the Joe Mann mine differs from that of other deposits of the Chibougamau area that are exploited by Les Mines Camchib Inc.. It is characterized by very fine first generation gold and very coarse second generation electrurn. Successful milling required adjustments of the processing flowsheet, which includes gravity, flotation, and cyanidation. A study of coarse gold liberation in the gravity/grinding circuit is described. Modifications to the flotation circuit and the reconditioning of a small capacity cyanidation circuit are presented. As a result of the circuit modifications, gold recovery increased from 65 to 81% in flotation and cyanidation. Overall gold recovery increased from 77% to 88-89%. These improvements are mostly attibutable to the recovery of -10 urn gold, whose presence in the Joe Mann ore and original circuit tails had been identified by process mineralogy.

Jan 1, 1989

By SIMON TIMBILLAH

The chalcopyrite-molybdenite (Cu-Mo) flotation industry is increasingly turning to organic depressants as suitable replacements for inorganic reagents, such as NaHS, due to environmental and safety concerns as well as high consumption rates of the inorganic reagents. This presents an opportunity for improvements or design and synthesis of alternative reagents. Disodium carboxymethyl trithiocarbonate (Orfom® D8) depressant is an organic depressant with a carboxylate group on one end and a trithiocarbonate group at the other end. Fundamental results are shown regarding the interaction of the Orfom® D8 depressant in the bulk flotation of a Cu-Mo concentrate from an operating North American mine. Cyclic Voltammetry on pure copper and Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Spectroscopy (XPS) measurements on pure chalcopyrite with Orfom® D8 depressant treatment are also reported. Through such characterization techniques a potential adsorption mechanism of Orfom® D8 on the mineral surface was identified and its depressant characteristics in the Cu-Mo flotation systems explained.

By T. K. Mukherjee, C. K. Gupta

"The importance of the processing of secondary resources such as solid industrial wastes and liquid effluents as well as byroducts for the recovery of the associated metal values hardly needs any elaboration. Such processing contributes in no small measure towards the augmentation of the availability and the supply position of resources. As an added benefit, it leads to a reduction in environmental pollution caused by the undesirable waste materials. As some typical examples of secondary resources in the Indian scenario, mention can be made of spent catalysts, metal/alloy scrap, ash, consumed batteries, flue dust, slag, sludge and slime, pickling solutions, spent acids, plating rinse solutions, spent etchants, waste water from synthetic fibre manufacture and from tanneries etc .. These wastes constitute a source of a variety of non ferrous metals. In the processing of secondary resources like these, the techniques of hydrometallurgy such as solvent extraction playa pivotal role.This paper outlines the efforts made to use solvent extraction to recover (1) base metals such as copper, zinc, nickel and cobalt from a number of secondary resources like cake, and sludge (2) refractory metals like molybdenum and vanadium from sulphidic byproducts and spent catalyst and (3) nuclear metal like uranium from phosphoric acid. In the case of base metals, process flowsheet involving the use of acidic extractants such as DEHPA and PC88A have been optimised. The problem of iron removal from the leach liquor, which influences the metal recovery process significantly, has drawn a special emphasis. In the case of refractory metals, basic extractants like Alarnine 336 has been pressed into service to produce kilogramme quantities of pure salts of molybdenum and vanadium. Finally, the paper gives a brief account of plant experience in recovering uranium from phosphoric acid, using a solvent system comosed of DEHPA and TOPO."

Jan 1, 1996

By T. K. Mukherjee

The importance of the processing of secondary resources such as solid industrial wastes and liquid effuents as well as byroducts for the recovery of the associated metal values hardly needs any elaboration. Such processing contributes in no small measure.towards the augmentation of the availability and the supply position of resources. As an added benefit, it leads to a reduction in environmental pollution caused by the undesirable waste materials. As some typical examples of secondary resources in the Indian scenario, mention' can be made of spent catalysts, metal/alloy scrap, ash, consumed batteries, flue dust, slag, sludge and slime, pickling solutions, spent acids; plating rinse solutions, spent etchants, waste water from synthetic fibre manufacture and from tanneries etc. These wastes constitute a source of a variety of non ferrous metals. In the processing of secondary resources like these, the techniques of hydrometallurgy such as solvent extraction play a pivotal role. This paper outlines the efforts made to use solvent extraction to recover (1) base metals such as copper, zinc, nickel and cobalt from a number of secondary resources like cake, and sludge(2) refractory metals like molybdenum and vanadium from sulphidic, byproducts and spent catalyst and (3:) nuclear metal like uranium from phosphoric acid. In the case of base metals, process flowsheet involving the use of acidic extractants such as DEHPA and PC88A have been optimised. The problem of iron removal from the leach liquor, "which influences the metal recovery process significantly, has drawn a special emphasis. hi the case of refractory metals, basic extractants .like Alamine 336 has been pressed into service to produce kilogramme. quantities of pure salts of molybdenum and vanadium, Finally, the paper gives a brief account of plant experience in recovering uranium from phosphoric acid, using 'a solvent system comosed of DEHPA and TOPO.

Jan 1, 1996

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 F. A. Myzenkov

The technology developed by the authors uses new methods for raw material smelting in electric furnaces, a new autogenous method and apparatus for subliming smelting for antimony trioxide production and separation of antimony and gold. Concentrate produced from the ore deposits in Yakutia has the following average contents of main constituents, % by weight: 29.4 Sb, 1.2 Fe, 13.1 S, 40.0 SiO2, 0.2 As, 2.6 CaO and 45 g/t of Au. Unlike the technology used abroad a new autogenous method makes it possible to increase considerably specific capacity and reduce gold losses with antimony trioxide by several times. At the same time mineralogical composition of trioxide has improved considerably ? it has mainly a cubic base with prevalence of senarmontite. The content of a main component (Sb2O3) in the final product has increased from 99.0% up to 99.6% which means better quality and makes it suitable for use in special technologies. Despite a lower antimony content of the concentrate (29.4% as compared with over 33% as common in the world practice), an antimony recovery of 85.3% into a commercial-grade product has been achieved, as well as a gold recovery of 96.65% into a gold-antimony alloy. The technology for processing gold-antimony materials developed and introduced at the Ryaztsvetmet plant is unique in the world with respect to gold recoveries.

Jan 1, 2006

By Batric Pesic

The interactions of mineral-pyrite with T. ferrooxidans were studied by using a cyclic voltametry technique. The interactions with bacteria were carefully examined during the entire growth stage of bacteria (fermentation). Several very important discoveries were made. For example, the pyrite surface invariably drastically changed its properties at the second day of fermentation. Beyond two days of fermentation, the cyclic voltamograms were insensitive to convective diffusion produced by stirring. The SEM study revealed that bacteria populated the pyrite surface at an extremely high density levels. The high density of bacteria, and the solid reaction products formed on the pyrite surface created conditions for pore diffusion which explained why the CVs became insensitive to convective diffusion in solution (stirring).

Jan 1, 1990

By B. Farouk, Y. G. Kim, D. Apelian

"Continuous strip casting has received considerable attention in recent years due to its economic advantages with increased energy savings and the elimination of intermediate processing steps. A promising concept in strip casting is the twin-belt (Hazelett) process which incorporates two cooled continuously moving thin metal belts wrapped around pulleys which tension and drive the belts at a predetermined speed. Molten metal is introduced at the entry end of the caster through a tundish and feeding nozzle into the mold. The twin-belt process has been successfully used with non-ferrous metals such as aluminum, copper and brass, and is a prime candidate for strip casting of ferrous materials. A numerical model has been developed which predicts the interface locations, the temperature fields in the solid and liquid regions of the cast and the velocity fields of the liquid metal at the entrance region of the twin-belt caster. The process variables considered are the velocity and cooling conditions of the belt and the nozzle shape. A body fitted coordinate system is used to track the front locations and to solve .the Navier-Stokes equations in the liquid region. Results obtained can help design efficient casters for thin strip steel castings. The development of the numerical model is presented, and sample results are discussed. I. IntroductionContinuous strip casting of steel has attracted world-wide concerns in recent years due to its economic advantages with increased energy savings and the elimination of intermediate processing steps. New methods of thin strip casting of steel are developing. One of the promising concepts is the Hazelett process, which is being used in nonferrous applications. The process incorporates two continuously moving, intensely cooled, thin metal belts. Metal blocks linked together are sandwiched between the moving belts and form moving side mold walls.In this work, the freezing front position, the temperature field and the liquid region flow field will be analyzed for the strip casting of metal using the twin belt caster (the Hazelett process). Up to now almost all theoretical analyses undertaken of the continuous casting of metal [1-3] have used a heat conduction equation, assuming slug flow in the liquid region. The effect of convection in the liquid pool during continuous casting were first investigated by Szekely and Stanek [4]. They considered potential flow between the feed metal orifice and the liquidus front, and slug flow in the mushy and solid regions of a vertical static continuous casting process for steel. Viscous effects and natural convection affects were not included Kroeger and Ostrach [5] studied the effect of natural convection flow in the liquid pool during solidification for a pure metal."

Jan 1, 1986

By Antti Roine

HSC Chemistry is a widely-used therniochemical tool in the chemical and metallurgical industries and in universities. The main reasons for it's popularity is the easy user interface and the large integrated thermochemical database. This paper summarizes the main properties of the new HSC Chemistry version 3.0, and gives a short review of the new features: Some metallurgical applications with the new features are also presented. HSC Chemistry 3:0 contains seven calculation modules and a thermochemical database with more than 11 ,000 chemical compounds. The new spreadsheet type table editor gives more control to the user, the new graphics routines have fewer limitations and more formatting properties. The capability and speed of calculation routines have also been improved.

Jan 1, 1998

By Luben Xie, Lin Hu, Qiang Wang, Min Gan, Tao Jiang, Wenqi Li, Yi Wang, Xiaohui Fan

"The mineralization behaviors of typical fluxes are studied by investigating the microstructures with optical microscope. The results show that the reactions begin with between iron ore and lime, limestone with small particle to form primary liquid. Then coarse limestone, dolomite and serpentine take part in reaction under the action of primary liquid. Limestone is the easiest to mineralization, next dolomite, and the last is serpentine. The higher basicity and smaller fluxes size favor the mineralization process of dolomite and serpentine.IntroductionThe purposes of adding fluxes into sintering are that:(1) to increase the basicity of sinter, so as to reduce even eliminate addition fluxes into BF(blast furnace) and decrease the coke ratio of BF[1,2]. (2) to decrease the melting point of sintering mixture to ensure sintering can be carried out at a lower temperature and reduce the energy consumption. (3) to improve the qualities of sinter by forming binding phase with iron ore fines [3].Flux is another significant component for sinter besides iron ore, especially for high basicity sinter[4]. The proportion of flux is usually higher than 10% in sinter mixture(excluding return mine).There were many reports about the influence of the flux types on sintering, such as limestone, dolomite, lime and so on[5-7]. It is very important to choose suitable fluxes for iron ore sintering. Although the effect of flux size on sintering also has been researched, the mineralization behaviors of the fluxes in the sintering process has not been illuminated. The paper will study the mineralization behavior of fluxes in sintering."

Jan 1, 2011

By M. Waladan

The top submerged lancing Sirosmelt system has been developed through laborator.y scale testwork and pilot plant trials for recovery of zinc from ISF slag. The effects of the process variables of gas injection rate, method of coal feeding, and temperature on zinc fuming rates were studied in the laboratory. It was found that the rate of zinc elimination was dependent on all of these variabl.es. The rate of zinc removal from slag was independent of zinc content of slag down to approximately 1.5% Zn, below which the rate was proportional to zinc content in slag. Pilot plant trials were carried out to evaluate a proposed process and results followed predictions from the laboratory scale tests. A comparison of the proposed process with conventional slag fuming operations is made and it is shown that the process has a number of advantages which have a significant impact on the economics of zinc slag fuming.

Jan 1, 1990

By Makoto Suzuki

After hot rolling, stainless steel strip is processed by the Hot Rolled Annealing and Pickling line (HAP) , where H2SO4 or mixed acid of HNO3 and HF is normally used. In the pickling bath, metal oxide accumulates in the form of sludge, which should be removed from the bath regularly. A new automatic continuous sludge disposal system has been introduced at Chiba Works of Kawasaki Steel Corporation to increase sludge removal efficiency and improve the working environment. The elements of the equipment are as follows. a. Ejectors in pickling bath: to carry the mixed acid into the circulation tank through the piping system. b. Sedimentation bath : to sediment sludge out of the bath. c. Skip conveyer : to convey a specified volume of sludge into a kneading for device for neutralizing. The sludge removal efficiency of this system is very high. and the volume of sludge accumulation in the pickling bath has substantially decreased.

Jan 1, 1996

By Zhenyang Wang, Xingle Liu, Xiangdong Xing, Shan Ren, Hongen Xie, Jianliang Zhang

"Non-isothermal combustion experiments of different additive amount of bituminous (0, 20, 40, 60, 80, 100 wt%) were conducted by synthesized thermogravimetry analyzer(STA409PC) from room temperature to 900°C in air. The changes of combustion characteristic parameters o f pulverized coals in different atmospheres are analyzed. The results show that DTG curves of coal combustion move to low temperature zones when the amount of bituminous increases. It indicates that both ignition and burnout temperature are lower, burnout time decreases, combustion characteristic index obviously increases, and combustion performance of blending coal are improved. The iso-conversional method involving Kissinger-Akah-Sunose (KAS) method was used for the kinetic analysis of the main combustion process. The results indicated that, when the additive amount of bituminous varied from 0 to 100 wt%, the value of activation energy which would sharply reduce if the additive amount of bituminous was under 60% increased from 133.94 kJ•mol-1 to 78.03 kJ•mol-1by using KAS method.IntroductionPulverized coal injection (PCI) to blast furnace (BF) is an important way for saving energy and reducing resource consumption during the ironmaking process. In order to acquire higher coal injection quantity, the relevant research topics in the field of pulverized coal combustion technology such as enhancing the efficiency of pulverized coal combustion, improving the combustion characteristics and reducing the harmful gas emissions and so on received extensive attention in recent years [1,2]. The combustion of blending coal when the appropriate proportion is selected for coal and also mixed well- distributed could give full play to the advantages of various types to make up the defects of single coal which is widely used throughout the world. So the blending coal injection to BF could produce a good impact on safety and economy for productive process. Therefore, a large amount of experimental researches on the combustion characteristic of blending coal for anthracite and bituminous were carried out by experts and scholars around the world [2-7].Nevertheless, the systematic research on the combustion behavior of anthracite with different content of bitumite in a thermogravimetric analyzer (TGA) is less. So in this paper, using the method of multiple scanning rate of conversion method, bituminous to promote the pulverized coal combustion reaction was studied to analyze its promotion mechanism of pulverized coal combustion reaction process, and the kinetic parameters of activation energy was also calculated, which to provide theoretical basis for the rationalization of resource utilization."

Jan 1, 2014

By M. J. Adam

The U.S. Bureau of Mines has investigated the partitioning of complex minerals to simpler phases using sulfidation reactions for selective extraction of mineral values. This report describes research in which thermal processing of the complex Ti-bearing mineral ilmenite (FeTi03) resulted in partitioning of the valuable Ti metal to the simpler compound rutile (TiO2). Samples of ilmenite were blended with elemental S for thermal treatment at various temperatures under controlled atmospheres in an effort to dissociate the Fe from the ilmenite complex. Product characterization revealed that the Fe was partitioned 'from the ilmenite, forming a rim of pyrrhotite/pyrite (FeS/FeS2) on a rut il e core. The products were agate milled and then subjected to cursory magnetic and flotation techniques in an attempt to physically separate the partitioned phases. Partitioning results and phase concentration data are reported relative to thermal treatment variables and physical separation techniques.

Jan 1, 1991

By Zhang Qin

Dolomite is main impurity mineral in phosphate ores. In practice of phosphate ores production, the grade of concentrates is only containing P2O5 31-32%.In this study, even the increasing of floatation reagent consumption and decreasing of floatation recovery, economic performance is estimated high according to the decreasing of H2SO4 consumption in subsequent production of phosphate fertilizer and the increasing of products value. In floatation stage, influence factor include the synergism impacts of floatation collector, the stages, time, concentration of ore pulp, which were discussed respectively in this paper. Raw material is characterized by mineralogy, chemical analysis, the grain size analysis and milling test . The results show that the grade of concentration can reach to P2O5 36% by deeply de-magnesium oxide from phosphate ores by floatation , which yield a high added value.

Jan 1, 2009

By Finlay Campbell

Nickel laterite pressure acid leach plants and reduction roast plants have had a checkered history in their engineering, construction, startup and operational reliability. Many potential projects have been the subject of detailed studies over the last thirty to forty years but relatively few have advanced to commercial production. Four reduction roast plants are currently operating, an additional one was partially constructed but never completed, and another was started up in 1974 and shut down after 12 years operation. Three acid leach plants have been built and commissioned in the last five years, trying to follow the example of the Moa Nickel plant in Cuba. An additional acid leach plant project is currently on hold, following limited construction work, its future subject to review by the owner because of potential cost over-runs. This paper attempts to discuss difficulties that may be encountered as a project is developed and will address factors which may affect production ramp-up schedule, long term production performance and overall production success. Comparisons are made with ramp-up performance at other large metallurgical plants that employ some comparable unit operations. Keywords: Caron, PAL, nickel laterite ore, ramp-up, reliability, process development, equipment design, step-out, commissioning, startup.

Jan 1, 2004

By He De-wen

The influence of coal desulphurization by fungus was experimentally studied. The present results suggest that fungus can effectively remove inorganic and organic sulfur in coal. The main factors that influence the desulphurization by fungus such as pH value, temperature, coal slurry concentration and coal granularity are studied by orthodox experiment and the optimal experimental conditions are as follows: pH value 6, temperature 45 C, coal slurry concentration 10% and coal granularity 100 m. Under the above conditions, fungus can remove up to 44.96 total sulfur and 54.87 inorganic sulfur within two days and their desulphurization rates will increase along with time. Compared to sulfolobas, desulphurization by fungus is steady and more effective and has the advantage of high speed.

Jan 1, 2006

By Xiaobing Yang, Abhishek Lahiri, Animesh Jha

"In the FFC-Cambridge process, the cathodic dissociation of oxide and CO/CO2 production on carbon anode is the basis for metal production in a CaCl2 bath. By using an inert intermetallic anode, the CO2 evolution can be eliminated altogether with acceleration in the electro-reduction kinetics. At present the process suffers from slow reduction kinetics of TiO2 to Ti metal, which can be enhanced significantly by the incorporation of alkali species in the TiO2 pellet at the cathode and in the CaCl2 bath in the presence of an intermetallic inert anode. Nearly full metallization with greater than 99% of Ti metal containing 1500 ppm of oxygen is possible to achieve in less than 16 hours of electro-reduction. Analyses of phase composition and the microstructures morphology in fully metallized pellets revealed the presence of localized solidified Ti layer, indicating that fast reduction process also involved formation of liquid phase as middle stage reaction. In addition, in situ creation of porosity and maintain higher current level during electrolysis process were two key factors to fully reduction of TiO2.IntroductionDuring cathodic dissociation of TiO2 in a CaCl2 bath and anodic evolution of CO2 on a carbon anode, which is the basis for the FFC Cambridge process [1], the rate of metallization slows down due to the formation of CaTiO3 at the reaction interface. Calcium and alkaline earth perovskites are known for their poor electrical conductivity which adversely affects the overall electro-reduction. One of the ways to increase the porosity is via the addition of polyethylene precursors in the pellet or by directly starting from perovskite [2, 3]. The experimental evidences shown in the literature confirm although the speed of reaction increases, but a complete or near complete metallization is not possible by enhancing the in-situ porosity alone, as the insulating perovskite is very slow to decompose under the equilibrium that prevails in the cell. Plethoric evidences on carbon anode show with the current decrease gradually, and finally stabilize at a very low value between 0.2 and 0.4 A, which is a testimony of the presence of perovskite insulating barrier in the current path. Our aim in this paper is to demonstrate the mechanism of enhanced electro-reduction when alkali ions are present in the oxide pellet at cathode and in the bath. We also show for the first time the use of an intermetallic anode for Ti-metal production using the FFC Cambridge process."

Jan 1, 2009

By S. Gopalan, J. D. Milshtein, S. N. Basu

Production of syngas is proposed utilizing the W/W03 redox system and employing a solarpowered two-step thermochemical cycle. Three chemical reactions occur in two chambers. Assisted by a solar concentrator, a high temperature reaction reduces W03 powder to metallic tungsten in both chambers. Subsequently, the temperature in one of the chambers is lowered and H2(g) is produced via re-oxidation of the tungsten powder using steam. The temperature in the other chamber is simultaneously lowered to an intermediate temperature and CO(g) is produced via oxidation of the tungsten powder using C02(g)· The gas streams coming out of the two chambers result in the syngas production. A complete thermodynamic analysis of the system is described. The W/W03 redox cycle offers greater gravimetric fuel productivity compared to previously proposed systems, and the entire cycle can be operated below 1273K.

Jan 1, 2013

By Chunlin Chen

Nickel-sulfide minerals are normally associated with copper and iron sulfides and often contain a minor amount of valuable metals such as cobalt and detrimental impurities such as arsenic. Metal losses in slag vary from process to process during the pyrometallurgical production of nickel and, depend on the feed composition, slag chemistry and operating conditions. Maximiz the metal recovery is one of major considerations to optimize operating condition for nickel smelting/ converting processes. At the same time, the deportment of minor elements between various phases during nickel smelting is of great importance by smelter operators. The Multi-Phase Equilibrium (MPE) is a thermodynamic package developed by CSIRO for simulating reactions between phases in multi-component and multi-phase systems [1]. Over the years the capability of the MPE model has been extended to cover the behavior of a large number of elements in high temperature systems. The sulfide smelting module of the MPE, which covers the minor elements such as As, Bi, Sb, Pb, Se, Te, Sn, Co and Zn, is capable of modeling the deportment of major and minor elements between various phases during nickel smelting. In this article the application of the MPE model in modelling the nickel smelting process is presented. The modelling results on the majors and minors are compared with the plant data. The deportment behaviour of arsenic in nickel smelting was analysed and the impact of slag chemistry on slag properties was modelled. These results can assist process metallurgists in exploring the optimum fluxing strategy for smooth operation and the potential practices for improving arsenic removal.