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By S. Kang, D. G. C. Robertson

Slag cleaning furnaces require extensive wall cooling because they involve the use of a superheated slag bath. This is in direct contrast to smelting furnaces, where the wall is usually (but not always) protected by "banks" of solid charge. In order to understand the heat transfer and flow in slag cleaning furnaces a number of model studies have been carried out using molten wax to simulate the slag. Wax is a good model fluid because, like slag, it has a high Prandtl number. Wax models cannot simulate the behavior close to the electrodes (DC arc or AC submerged), but they can and do give a good simulation of the flow and heat transfer at the wall. An understanding of these phenomena is of great importance for the design of cooling panels in the walls of the furnace. Since superheated molten slag will eventually wear away any refractory bricks over time, the wall cooling must be designed to form a frozen layer of slag, referred to as a "freeze lining". The heat flux density (Q/A) required to do this is given by Q/A = h* ?T, where h is the heat transfer coefficient in the slag phase at the wall, and Li T is the superheat (bulk slag temperature - liquidus temperature). Both Q/A and h vary greatly with position and both are usually a maximum at the slag line. In the experimental work, molten wax baths were heated by block heaters to provide similar energy densities to those encountered in commercial slag cleaning furnaces. This procedure was considered to be valid since most of the electrical energy into a furnace bath is dissipated as heat. Gas stirring was used to simulate the gas evolved at the electrode in real furnaces - the quantity of this gas could be estimated from a knowledge of electrode consumption. The similarity criterion was equal gas flow per unit area of surface, in model and prototype. Heat transfer coefficients were measured in the models as a function of power density, gas stirring, superheat, etc., and could be related to the full-scale operations by the use of dimensional analysis.

Jan 1, 1999

By Jeffrey W. Braithwaite

The laboratory characterization of the oxidation of chalcopyrite under conditions of deep solution mining is presented in this paper. A salient feature of this system is the pH buffering effect resulting from simultaneous acid producing and acid consuming oxidation reactions. The solution chemistry and related sulfur partitioning of the oxidation reactions are detailed. The contribution of temperature, acid concentration, oxygen pressure, particle size, and solution additions to the kinetics of copper extraction are presented. A mixed kinetic model was used to describe the kinetics of oxidation.

Jan 1, 1976

By Riyad N. Ahmad-Bitar, Shadia J. Ikhmayies

"CdS/CdTe solar cells were built by depositing a 200 nm layer of Sn02:F on glass substrates by the spray pyrolysis (SP) technique, a 500 nm CdS:In layer by the same technique and a 1-1.5 µm CdTe layer by vacuum evaporation. The cells were CdCh heat-treated in nitrogen atmosphere for 30 minutes at 350 -.C. The photoluminescence (PL) spectra were measured at the CdS/CdTe interface for two cells with different values of the CdTe layer's thickness at temperature T = 60 K. A deconvolution peak fit was performed from which it is found that the peaks are characteristic of the solid solution CdSxTei-x· The parabolic relation that relates the bandgap energy with the composition was used to estimate x, where xis [S]/([Te]+[S]) and [Te], [S] are the concentrations of Te and S atoms respectively. The results show that the interface is smooth and the change of the bandgap occurs gradually.IntroductionCdS/CdTe heterojunctions represent a combination of materials promising various applications, and for solar energy conversion in the first place [1]. In photovoltaic cells the CdS material acts as a wide bandgap window. Direct bandgap CdTe with high optical absorption coefficient is used as an absorber [1]. Solar cells with efficiencies of 10 to 16% have been obtained with CdTe grown by close space sublimation, electrodeposition, vacuum evaporation and rf sputtering methods [2]. In this work the CdTe layer was prepared by vacuum evaporation because it results with films of minimum impurities, while the Sn02:F and CdS:In layers were deposited by the spray pyrolysis technique because it is a low cost method which enables intentional doping and large area thin films."

Jan 1, 2011

By J. Sjöblom

New copper and nickel processes, flash converting and DON, direct high-grade nickel matte smelting, have been developed in order to replace the conventional and not so environmentally friendly PS-converting process. With a laboratory scale laminar-flow furnace the combustion reactions of sulfidic feed particles can be investigated under simulated flash smelting conditions. In the present study, finely ground and screened feed fractions of a copper matte and a nickel matte were flash oxidized in a laminar-flow furnace. The experiments were carried out using 20, 21 vol% and 75 vol% O2 in nitrogen, at temperatures 1100 and 1300 °C and reaction zone length of 7.5-16 cm. The samples were quenched in a water film after a specified reaction time. The matte particle reactions were stopped after short residence time intervals in order to obtain a better understanding of the reaction mechanisms. Chemical analysis was used to determine oxidation degree, and optical and scanning electron microscope combined with energy dispersive analysis was used for characterization of the reacted particles. On the basis of the experimental results the reactivity of the mattes is discussed and possible reaction and dust formation mechanisms are considered.

Jan 1, 1999

By Grant E. Casley

Since 1970 Mount Isa fines Limited has made a significant increase in blister copper production from approximately 100,000 to 155,000 mt per annum and in fact 161,040 mt were produced in the calendar year 1974. Flowsheet developments including fluidised bed roasting and converter slag flotation are discussed, particularly their contributions to minimising major equipment changes in smelting and converting. The use of model- ling and simulation techniques for such an exercise is mentioned. The paper reports the alterations made to both equipment and operating techniques in the reverberatory furnace and converter sections to achieve the regular production of 250 mt of blister per converter day from a 41% Cu matte grade. The effects of flux composition on converting performance are highlighted. The air quality control programme is discussed in relation to its restriction of blister copper production.

Jan 1, 1976

By Roy J. M. van Lier

In industrial aqueous solutions, germanium generally occurs in trace amounts amid high concentrations of other metals, such as zinc, copper and iron. Separation of germanium from these metals as well as its isolation from gallium and indium pose a real challenge to the hydrometallurgist. After a brief discussion of the aqueous chemistry of germanium, this paper reviews the flowsheet of the Apex Mine in Utah. The Apex property was the only mine in the world to be operated primarily for production of gallium and germanium, but apparently closed due to great operating difficulties. Several process variants proposed for the treatment of the Apex ore, including bioleaching methods, are addressed. Following a more general description of the behavior of germanium in hydrometallurgical zinc processing streams, available technology for its recovery from aqueous solutions is summarized. Precipitation, solvent extraction, ion exchange, electrowinning, ion flotation and liquid-membrane separation are all outlined in terms of the aqueous chemistry of germanium. Finally, the production of high purity germanium dioxide and metal is briefly discussed

Jan 1, 1995

By I. Gaballah

About forty percent of the SOx emissions are generated during the processing of metal sulfides of Cu, Pb, Zn, Ni, etc. Although new technologies for metal sulfide's smelting allow the production of H2S04 with a reasonable cost and decrease the emissions of sulfur oxides, the generated quantity of SOx is considered as a serious threat to environment. This paper suggests alternatives for low temperature processing of complex sulfide ores or concentrates 'CSO or CSC' under neutral, reducing and chlorinating atmospheres or their combination. At T > 400 "C, The neutral and reducing treatments allow the decomposition of pyrite and the partial recovery of sulfur as So and H2S. At 300 "C, the chlorinating treatment of CSC is fast, exothermic and allows the separation of FeC13 from the valuable elements' chlorides. It also generates SyCIx that can be either reduced by H2 or hydrolyzed in presence of sodium sulfide. The recovery rate of elemental sulfur with respect to the sulfur input exceeds 90 %.

Jan 1, 1999

By Nicolas Reynier

The separation of radionuclide during rare earth element (REE) production is an important requirement for developing the Canadian REE mining industry. Separation of actinides from REE is often a large concern in the rare earth industry because of the need to manage the radioactive nuclides. A patented process developed for actinides extraction from radioactive wastes was applied to REE ore. Objectives were to optimize the process for REE leaching from ore, and separate radioactive impurities from sulphuric and nitric liquor by ion exchange (IX). Ore leaching was optimized using a surface response plan to ensure statistical significance. In optimized conditions, solubilization yields ranged from 90–95% for Th, 60–75% for U, 48–55% for LREE, and 59–75% for HREE in sulphuric and nitric media. Both media were compared for radionuclide removal from rich REE-bearing mineral liquor by IX. Actinides separation ranged from 92–97% for Th and 69–96% for U in sulphuric and nitric media.

By S. R. Reddy

Thennodynamic properties of several quaternary systems are calculated using our recently modified Margules equations. The modified Margules equations are expressed up to infinite order in the vicinity of solvent. Quaternary system of one solvent and three,solute partials are derived. First order interaction coefficients of binary, ternary and cross -interaction parameters of quaternary system are used to'evaluate the partial functions. In the original fonn of Margules equations,derived partial functions are convergent and same 'as Unified ,Interaction Parameter Fonnalism. But considering up to infinite order of the Margules coefficients, the functions are divergent, in order to overcome this restriction, Margules equations are modified to get consistent equations. Derived partial functions are thennodynamica Hy consistent with Maxwell and Gibbs Duhem relations. The derived logarithmic activity coefficient of the solvent and solutes are consistent with the ternary systems. The calculated data, ie., activity coefficient values of nitrogen and interaction coefficients are in good agreement with the data of Fe-Cr-V -N. Fe-Ni-V -N, Fe-Cr-Ta-N and Fe-Ni-Ta-N systems.

Jan 1, 1999

Equilibrium calculational software programs can be effectively utilized to illustrate the importance of activity or concentration, solubility, temperature, solution pH, solution potential, and ligand complexation to students studying hydrometallurgy. The calculational program STABCAL will be demonstrated. illustrative examples for the creation of diagrams such as EH-pH, activity or concentration-pH and activity or concentration-EH will be presented to demonstrate the fundamentals of real hydrometallurgical systems. Speciation, titration and mixing will be used to simulate or predict operational processes. Applications will include treatment of Acid Mine Drainage (Berkeley Pitlake water and sediments), mass balance potential/pH diagrams, leaching and selective separation of metals from electroplating sludge, metal adsorption at femhydrite surfaces, and flowsheet development for treating mercury sulfide K106 sludge.

Jan 1, 2002

By Arsenio Enriquez, Adrian Deneys

"Rio Tinto through its subsidiary Kennecott Utah Copper Corporation (KUC) and Praxair have implemented the CoJet® gas injection system for copper anode refining. The system provides the capability to melt on average 60 to 70 tons of scrap copper per heat (with acceptable NOx emissions). The system has demonstrated the potential for tuyere-less sulfur and oxygen removal using coherent jet technology.This paper describes the process concept, system development, laboratory testing, implementation, current operation and ongoing developments."

Jan 1, 2009

By Mokka Rao, Asdrubal Serrano

"A mathematical model is developed which describes the movement of the minerals present where the vertical and angular velocities are related with the different operative parameters involved in the process of separation of silica from iron ore, which permit maximise the capacity of the spirals to obtain major productivity. The process is realised in two steps, of the rough dressing and other cleaning. Through the results obtained for chemical analysis of the final products of each spiral and the equation of movement of particles, it is proved the applicatibility and efficiency of mathematical model to operating parameters of the spiral. Moreover, it is determined though the recuperation of the final products of quality in the use spiral HC 1870 and HG 8/7. INTRODUCTIONThere is prospetive of increasing the production the iron ore in agreement with the demand of siderurgical proyects united with the external demand of quality 40 million tons per year. The Ferrominera de Orinoco Company is experimenting two types of modem spirals, Humprey (HC 1870) and Reichart (HG 8/7) which have limited capacity. For this reason this investigation designed a mathematical model with which larger units can be designed for increasing the capacity of the spiral."

Jan 1, 1999

By William K. Connor, O&apos

The U.S. Bureau of Mines (USBM), in cooperation with the American Society of Mechanical Engineers (ASME), conducted over 200 hours of melting tests to vitrify residues from five municipal waste combustion facilities. Combined residues (grate residue and f1yash) from three municipal waste combustors, a waste water treatment sludge combustor, and flyash from a refuse-derived-fuel (RDF) boiler, were sequentially melted in a I-metric-ton (mt) water-cooled-wall electric arc furnace. Each of the residues underwent magnetic separation, screen size analysis, and bulk chemical analysis prior to melting. The furnace products were examined by optical and electron microscopy and by X-ray diffraction. Bulk chemical analyses were acquired for the metal, fume, and vitrified furnace products. The material balance for the furnace operation indicates that from 69 to 86 pct of the feed reported to the vitrified furnace product, which had leaching potentials well below the EPA limit for each metal, as determined by the EPA TCLP. The electric arc melting furnace currently is being utilized in a cooperative research project between the USBM and the Idaho National Engineering 'Laboratory (INEL) for melting tests on simulated low-level radioactive wastes,

Jan 1, 1991

By Dae Jin Ha

Sticking phenomenon occurring during hot rolling of two STS 430JlL ferritic stainless steels was analyzed by hot-rolling simulation tests. The sticking started from the initial nucleation stage in which the rolled materials were stuck onto the roll specimen surface, proceeded to the growth stage in which stuck fragments grew further, and reached the saturation stage. The modified 430JlL steel had a smaller number of sticking nucleation sites and slower growth rate than the conventional 430JlL steel because of higher high temperature hardness, thereby leading to less serious sticking. When the simulation test was conducted at 1070 °c, Cr oxides were formed on the surface of the rolled materials, and thus the sticking was drastically reduced because of the increased surface hardness of the rolled materials. In order to prevent the sticking, high-temperature properties of the rolled materials should be enhanced when rolled at 900°C or 1000 °C, and rolling conditions and alloying compositions, under which the oxide formation was promoted, were more important than high-temperature properties when rolled at higher temperatures than 1000 oC.

Jan 1, 2008

By Jillian Spindura

This work investigates the carbothermic reduction of the complex sulphide mineral, pentlandite, in the presence of lime. The effects of change in temperature and the use of different carbon sources are studied and the role of these variables on the reducibility of pentlandite mineral is discussed. The microstructures of the heat-treated pellets are examined using X-ray diffraction and scanning electron microscopic techniques. The latter analytical method also allows any variation in the morphology and composition of the metallic phases formed, with temperature, to be considered. The kinetics of the reduction process is studied and the magnitude of the overall activation energy is determined from the plots of percentage reduction versus time.

Jan 1, 1996

By Dong Liang, Qijie Zhai, Zhichen Zhang, Qixin Li, Zhishuai Xu

"The formation, distribution and survival of pure Al nuclei under surface pulsed magneto oscillation (SPMO) treatment were investigated with thecombination of experiments and numerical simulation. The results indicated that the nuclei originated from the whole top surface of melt owing to the oscillation of top surface induced by SPMO. The temperature field significantly affected the survival of the nuclei The electromagnetic force and flow field of the melt with SPMO treatment were simulated by finite element software ANSYS. The electromagnetic force mainly distributed below the top surface near the mould wall. The electromagnetic farce not only made the melt oscillate but also increased the convection of meh below the top surface vigorously. The oscillation near the top surface of the melt promoted the nucleation largely, and the convection increased the uniform of the temperature distribution in the whole meh which favored the survival of nucleiIntroductionAs we all know, fine equiaxed grains are beneficial fur the improvement of the mechanical property, process ability and the uniformity of metallic materials [1-2]. With the researches of recent decades, people discovered that the electromagnetic field is an efficient method to refine the solidified structure of metals [3-7]. Pulsed magnetic field technology obtains more and more attentions in recent years due to its smaller power consumption, bigger instantaneous magnetic field intensity, non-contacting with the meh and simple convenient equipment manufacturing [8-9]. However, the melts would splash fiercely when pulsed magnetic field is applied with a slightly higher power. Thus, based on the understanding of the solidification refinement mechanism of electric current pulse (ECP) [10], Gong et al [11] developed a novel technology called pulse magneto-oscillation (PMO) to refine the solidification structure. The technology can be easily applied in the solidification structure refinement of continuous casting slab. But fur aluminum continuous casting, the sump is very shallow, which greatly limits the application of pulse magneto-oscillation technology."

Jan 1, 2014

By F. -Z. Ji

Carbon injection into metallurgical slag is important in electric arc furnace (EAF) steelmaking for foamy slag practices and in nonferrous slag cleaning operations. The current publication presents kinetic data for coal injection into EAF slag to understand the interaction between injected carbon and metallurgical slag. Coal particles were injected into EAF slag and the kinetics were followed by gas and slag analysis. The results were analyzed, in terms of fundamental rate equations for each possible reaction step, as a function of temperature and slag composition.

Jan 1, 2003

By Batric Pesic

Solvent extraction of nickel and cobalt from the real leach solutions was studied by using a novel extraction system. The extraction system was a mixture of 2,6-bis-[5-n-nonylpyrazol-3¬y]] pyridine (BNPP) and dinonylnaphthalene sulfonic acid (DNSSA). The BNPP represents a novel molecule, which was designed and synthesized in our laboratory. Real solutions for the study were prepared by leaching of two different cobalt-nickel bearing concentrates, cobaltite [CoAsS] concentrate from Blackbird Mine, Idaho, and siegenite [(Ni,Co)3S4] concentrate from Missouri Lead-Belt. The major strength of the system was the selectivity of extraction toward nickel and cobalt from iron containing solutions. Other metals such as Mn, Mg, Ca, Al and As were not extracted. Due to the irreversibility of copper extraction, its removal from solution was required prior to the extraction of nickel and cobalt. Zinc was not as strongly extracted (i.e. its stripping was readily achieved) as was copper . Flowsheets for the recovery of nickel and cobalt were also developed.

Jan 1, 1997

By P. Blazy

A hydrometallurgical procedure for the recovery of metal from ore, particularly of copper from sulphide materials is described. In the course of this procedure, the raw material is first of all submitted to the action of an appropriate reducing system and then treated with a ferric salt solution which brings about the selective solubilisation of the elements to be recovered with respect to those constituting the pyritic phase. This procedure is investigated using two ore samples proceeding from massive sulphide deposits, presenting different chemical and mine- ralogical characteristics. The results of this investigation are compared with those obtained by a classical process employing a ferric salt solution. It appears that one solubilisation of copper takes place under particularly advantageous conditions when our procedure is used. The principal parameters affecting leaching of zinc, lead and copper are examined. The selectivity of this treatment is evaluated by following the change during the treatment in the pyritic phase.

Jan 1, 1976

By Chu Yong Cheng

The solvent extraction (SX) processes of the three pressure acid leach (PAL) nickel plants in Western Australia have been reviewed. The use of intermediate precipitation, solids/liquid separation and re-leach in the three W A nickel plants make these processes complicated and costly in capital and ?operation. The research work carried out by the SX group at the AJ Parker Cooperative Research Centre for Hydrometallurgy I CSIRO Minerals has led to the development of direct solvent extraction (DSX) processes to recover and purify nickel and cobalt from leach solutions. The simplicity of the process flowsheets and the expected savings in capital and operating costs are the major advantages of the new DSX processes over the reviewed processes. By using a new synergistic organic system in semi-continuous tests with a pilot plant leach solution (after iron precipitation) from BHP-BiIliton Stainless Steel Materials, the metal values (Ni and Co) together with zinc and copper were separated from the major impurities (Mn, Mg and Ca, together with Cl) in the first SX circuit. The co-extracted manganese, magnesium and' calcium were easily scrubbed out. After stripping, the metal values (Ni and Co) together with zinc and copper were concentrated, resulting in a much smaller second SX circuit and equipment in the down stream processes. The extraction and stripping kinetics of the metals with the new synergistic organic solution were very fast. The extraction and stripping almost reached steady state within 0.5 minutes. Semi-continuous test work with a synthetic leach solution, a cobalt pilot plant leach solution from Peko Rehabilitation Project Pty Ltd and a synthetic solution to simulate a concentrated laterite leach solution from BHP-Billiton Stainless Steel Materials showed that manganese, calcium, copper and zinc can be effectively and efficiently separated from nickel, cobalt and magnesium by extraction, scrubbing and stripping. This led to the development of another DSX process using D2EHPA to recover nickel and cobalt from leach solutions.

Jan 1, 2003