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By N. J. Themelis

In the last two decades, the Outokumpu flash smelting process has become the dominant new technology for copper smelting and has? also been applied to the smelting of other metal sulfides. The application of oxygen enrichment and improvements in concentrate burner and furnace design have resulted in ever increasing smelting rates per unit volume of the reaction shaft. This paper examines the. rate phenomena taking place in the reaction shaft of the Outokumpu furnace and compares information obtained from a mathematical model of heat and mass transfer rates to results obtained in pi1ot tests conducted at Pori, Finland, and to actual performance of a number of flash smelters around the world. 2?

Jan 1, 1985

By Young-Dae Kim, Dong-Sic Kim, Jong-Jin Pak, Kyung-Hyo Do

"Sulfur is one of the most harmful elements in stainless steel (SIS) products and the specification of sulfur content is getting more severe for high grade SIS. In order to accurately control the desulfurization reaction in high chromium containing SIS melts, it is important to know the thermodynamic interaction between chromium and sulfur in Fe-Cr melts over a wide range of chromium content. In this study, the equilibrium sulfur distribution, Ls, between a Ca0-Alz03 slag and Fe-Cr-C,.,-S melts were measured under CO atmosphere in the temperature range of 1823-1923 K. The specific effect of chromium on the activity coefficient of sulfur in the melts was determined with the consideration of carbon effect on sulfur. A separate experiment was carried to determine. Ls between a slag and FeCr- S melts (Cr: 0-30 mass%) at 1873K to check the validity of the thermodynamic parameter determined in the present study.IntroductionFerritic stainless steels containing chromium (Cr) up to 30 mass% have been developed for a good corrosion resistance and a high formability to replace austenitic SIS. Especially, Sulfur (S) causes a reduction of high-temperature strength and the hydrogen induced cracking (HlC) in stainless steel for line pipes. [l]Many studies on the desulfurization of hot metal and liquid steel have been carried out for several decades and they used HzS-H2 gas equilibrium technique for measuring the effects of many alloying elements on the activity coefficient of S in liquid iron. However, the study on desulfurization of Fe-Cr melts was very scarce.[2] In order to accurately control the desulfurization reaction of high Cr stainless steel, it is essential to know the thermodynamic relation between Cr and S in Fe-Cr melt over a wide range of Cr content and temperature.In the present study, the thermodynamic interaction between Cr and S in liquid iron was determined by measuring the equilibrium distribution ratios of S between Fe-Cr-C,.1-S melts containing a wide range of Cr up to 30 mass% and a 55 mass%Ca0-45 mass%Alz03 slag of which the sulfide capacity was pre-determined using Fe-C,a1-S melts in the temperature range of 1823-1923 K. The validity of thermodynamic parameter determined in the present study was checked by measuring the S distribution between a Ca0-Alz03-Mg0 slag of known sulfide capacity and liquid Fe-Cr-S alloy at 1873 K. Using Wagner's formalism, the results of experiment were thermodynamically considered to determine the effect of a specific concentration of Cr on the activity coefficient of S in liquid iron."

Jan 1, 2014

By Qinghai Pang

"With the increasing proportion of bituminous coal in blend coal, the safety of blend coal during pulverization and transportation is gradually being paid more and more attention. Therefore, the explosivity of bituminous pulverized coal (PC) with different volatile content from 25 to 38% was studied by measuring the combustion flame length after its injection into a glass pipe with the heat source installed in the center. The results indicated that high volatile content bituminous PC is apt to have higher explosivity. By blending different bituminous PC with 10% anthracite, the explosivity of bituminous PC showed a positive correlation with the proportion –OH radical. However, different bituminous PC seemed to have the same explosivity when the addition of anthracite increased to 20%. With the further increasing proportion of anthracite to 30%, the explosivity of bituminous PC with high –OH proportion became negligible while a weak explosivity of high –CH3 proportion bituminous PC still remained.IntroductionWith the increasing iron ore prices and decreasing steel prices, it has become critical for iron and steel enterprises to control the cost in ironmaking and steelmaking process. Blast furnaces (BF) are the main consumer in ironmaking process, which occupies 70% fuel consumption of total steelmaking process [1]. In this circumstance, any means necessary is taken by BF operators to lower the cost of iron in production. Coke and iron ore are the main expense in this process, who takes up a very high proportion in total cost. Pulverized coal injection (PCI) is the most efficient way to reduce coke ratio, which replace coke with relatively cheaper PC.At present, most of BF is injected with blend coal in the consideration of decent combustion property and quantity of heat. Simultaneously, bituminite and anthracite blending is an effective method to obtain blend coals with required composition and performance, such as volatile and ash content, etc. Nevertheless, a very huge gap was found between the price of bituminous coal and anthracite in some regions of China, in which the price of bituminite can be just 70% of the price of anthracite. Thus, iron enterprises in these regions attempt to possibly amplify the proportion of bituminite in blend coal. Increasing proportion of bituminite results in higher volatile content in blend coal, by which the safety of blend coal during pulverization or transportation was deteriorated.Relatively, coals with higher volatile content usually possess stronger explosivity, which means that volatile and explosivity may related to some extent. However, the relationship between volatile and explosivity is not of certainty for some PC with high volatile content around 40% was found to be inexplosive in comparison to the coals with lower volatile content. With the increasing proportion of bituminous coal in blend coal, investigations on the factors of PC explosivity have become more and more important. Therefore, bituminous coals with different volatile content were selected. The explosivity of blend coal and its relationship between volatile content and functionality was investigated in this research."

Jan 1, 2014

By J. Jakumelt

The coupled simulation of mold filling and solidification for an investment casting process presents difficult. This is due to the complexity of the carious physical process and the geometry, To achieve this task in a precise way, the CFD program FLUENT and the casting simulation tool CASTS were closely coupled. Any physical quantity, such as velocities or temperatures, can be exchanged via files after each time step of the simulation. The communication and operating sequence of the programs is controlled by PERL-scripts. This enables the expertise of FLU ENT for flow simulation and the strength of CASTS, for casting simulation to be combined. The coupled simulation was successful applied to an aerospace investment casting. Several physical models were tested for correct treatment of the casting filters, the porosity of the mold and the viscosity of the liquid metal. The results demonstrate that even complex investment casting geometries can be investigated using CASTS-FLUENT.

Jan 1, 2003

By J. Lui

The 15m high Inco flash furnace uptake was designed as a reaction chamber with the objective of destroying the H2S contained in the furnace off-gas by combustion with oxygen at about 1300?C. Until recently, the oxygen required for this purpose was injected through afterburners located at the bottom of the uptake. An undesirable side effect of this practice was the formation of build up accretions on the inside walls of the uptake. This buildup had a negative impact on both the furnace on line time and the control of the flash smelting process. In late 200 I, the afterburners were relocated to the roof of the uptake. As a result, about 80% of the uptake accretion buildup disappeared with obvious beneficial effects for the operation of the furnace. This paper discusses key flash smelting aspects that affect the operation of the flash furnace uptake such as the dusting rate, the formation of H2S in the freeboard of the furnace, and the impact of using coke to supply some of the heat required by the process. The mechanism of buildup formation and its dependence on uptake afterburners location are also examined. Prof. Yazawa's sulfide smelting thermodynamic relationships proved instrumental in understanding the conditions that influence the formation and the elimination ofH2S and uptake buildup.

Jan 1, 2003

By S. Abe

An extensive study has been carried out to determine the true cause of floating slimes precipitation which sometimes occurs and badly affects the quality of copper cathodes. Soluhilities of floating slime compounds systematically measured for the ternary system As-Sb-Ri added solely or in combination with conventional copper electrolyte (63°C) and bench scale electrorefining experiments done by varying electrolyte composition, have shown conclusively that the level of Sb(V) ions plays a substantial role in the precipitation mechanism. It was, therefore, speculated that controlling the level of the less soluble S b ( V ) ions below a certain critical level should result in a complete elimination of the undesirable precipitation. This can be easily achieved, for instance, by the addition of a reducing agent such as SO2 gas and the simultaneous employment of a certain type of cheating agent that effectively removes excessive Sb and Bi from the contaminated electrolyte. Long-term pilot testing conducted in line with the above speculation has confirmed the SO2/chelating resin scheme to be industrially very attractive and feasible.

Jan 1, 1987

By A. Deneys

An experimental technique has been devised for studying the reaction kinetics of the reaction: ZnO + 2Fe0 = Zn(g) + Fe203, by which zinc evolution can occur from a molten slag bath in the absence of a carbonaceous reductant. When studying the reaction kinetics by heating from room temperature, solid state reactions and poorly defined melting points may obscure the starting point of the reaction. In order to eliminate this problem, an experimental technique was devised whereby two molten slags could be melted independently, and then mixed, to provide a well defined starting point from which to begin taking measurements. Two crucibles were mounted in a vertical reaction cylinder. The upper, mild steel, crucible had a bottom pouring plug which was sealed by a steel stopper rod. A fayalite mixture was contained in this crucible. The lower crucible contained an A12O3-CaO-SiO2-ZnO solution. Once the two slags had been melted, the steel stopper rod was removed from the upper crucible. The upper, reduced slag (fayalite in equilibrium with the upper steel crucible), drained into the lower crucible where the two slags were mixed by submerged argon stirring. Dip samples were taken to measure the zinc content of the final mixture as a function of time. The experimental procedure will be described, as well as results of experiments which were conducted on synthetic slags. The system investigated was similar to the lead blast furnace slag which is produced by the primary lead smelters of Missouri, USA.

Jan 1, 1997

By José D. T. Capocchi

Viscosity of liquid lead, tin, and Pb-Sn alloys has been measured by the rotational viscometer method in the temperature range from 50 K above their respective liquidus temperature to 823 K. The results are accurate to within ±1.0 %. The variation of viscosity with temperature followed the Arrhenius-type equation µ = µo.exp(Q/RT). The composition dependence of the isothermal viscosity and the activation energy for viscous flow have not shown anomalous changes at the eutectic composition of the Pb-Sn system.

Jan 1, 2000

By Nicholas Zabaras, Deep Samanta

"Solidification of metal aluminum and aluminum alloys is modeled on uneven surfaces characterized by sinusoidal curves. Wavelengths and amplitudes of these sinusoidal surfaces are varied to study their effects on processes like solidification, macro-segregation and inverse segregation. Solidification and macro-segregation are modeled using a slightly modified form of a stabilized finite element method developed recently to model high Rayleigh number solidification and porous media flows. For pure metal solidification, the effect of varying amplitudes and wavelengths is observed in heat transfer, fluid-flow ~nd phase change processes. The relative importance of shrinkage driven flow and solutal convection on the redistribution of solute for an alloy solidifying in a rectangular cavity is compared. The analysis is then extended by modifying one of the surfaces to a sinusoid. In this case the effects of varying amplitudes and wavelengths are studied in heat transfer, fluid flow, phase change, macro-segregation and inverse segregation processes.1 IntroductionTransport phenomenon during solidification of alloys is a major cause ofcasting defects such as segregation, micro-voids, hot tears, porosity, internal and surface cracks. Heat flow across metal and mold surfaces directly affects the phase change process and plays an important role in determining freezing conditions within the metal. In alloys, natural convection and shrinkage play an important role in determining the final solute redistribution, macrosegregation and evolution of solid macromorphology. Surface unevenness plays an important role during the early stages of solidification. It influences the heat transfer rate and fluid flow in the melt, which in turn affect the morphology and shape of the solid-liquid interface. The effect of surface unevenness on solute redistribution is important during solidification of alloys, where solute driven flow in the mushy zone is prominent. Thevik and Mo in [7] and [8] used a one dimensional model for studying surface segregation and macrosegregation in alloys under the influence of exudation and solidification shrinkage. Air-gap formation in their model was expressed through a variable convective heat transfer coefficient at the boundary. Tsai et al. in [3] and [4] have modeled macrosegregation in an aluminum-copper alloy driven by shrinkage and solutal convection. They used a single domain model based on mixture theory and solved the transport equations using finite difference methods. Our aim is to model solidification of aluminum followed by macrosegregation and inverse segregation in aluminum-copper alloys on uneven surfaces by finite element methods. These surfaces are modeled as sinusoids characterized by amplitudes, ?s and wavelengths, As, By varying As and ?s, changes in heat transfer, fluid flow, phase-change and macrosegregation are studied."

Jan 1, 2004

By T. Shibaraki

A new larger, more efficient and economical Mitsubishi furnace line at Naoshima was put into operation in May 1991. Naoshima Smelter had produced previously about 230,000 mtpy anode copper with two smelter lines, i.e., a conventional reverberatory furnace line and Mitsubishi furnace line, which had been shutdown at the same time of the start up of the new smelter. At the beginning of the operation, there were several initial problems at the area of off gas trains and feeding system. By overcoming them now the process has been continuing satisfactory operation at the design rate. The paper describes about the design concepts and the actual operation of the new smelter.

Jan 1, 1993

By K. Osseo-Asare

"The molecular structural and solution chemical characteristics that underlie the surface activity of solvent extraction reagents are highlighted, with particular emphasis on the tendency towards reverse micelle and microemulsion formation. The physicochemical factors that lead to microemulsion-enhanced solvent extraction with chelating extractants are elucidated. Membrane-based contactor systems are described which are uniquely suited for enhanced solvent extraction with microemulsions. The possibility of combining solvent extraction with microemulsion-mediated materials synthesis is discussed. IntroductionThe discovery of new selective extractants has resulted in major breakthroughs which have helped to establish solvent extraction as a versatile separation technology (1-3). A complementary strategy towards new process development is to seek new ways of using the available reagents. This paper explores this second approach. From a molecular structural standpoint, an extractant may be viewed in terms of two components: a polar functional group and a hydrocarbon radical. In the conventional view of solvent extraction, this molecular structure serves two main purposes: The polar functional group provides the binding sites for complexation of metal ions, while the organic group is needed to render the resulting metal-extractant complex organic-soluble. But are these the only properties of the organic and the polar groups that are relevant to the solvent extraction process?In this paper, attention is directed to the fact that solvent extraction reagents possess the molecular structures of amphiphiIes; that is, they are characterized by the presence of spatially separated hydrophilic and hydrophobic groups on the same molecule. A case is made for the view that this amphiphilicity offers interesting opportunities to develop new separation processes which collectively may be described as enhanced solvent extraction (4-6)."

Jan 1, 1996

By I. D. Reznik

The flowsheets of converter matte production from sulphide copper - nickel and oxide nickel ores on Severonickel and Yuzhuralnickel integrated ,;corks are given. The cobalt behaviour in electrosmelting and autogenous ore smelting, converting and converter slag cleaning is observed. A list of acticles published in the 80 th is given.

Jan 1, 1993

By Guy L. Fredrickson

A modified transpiration reactor was used to measure the composition of the equilibrium gas phase formed above compounds in the Hg-O-S system at high temperatures (600 to 900K). A thermodynamic database {(AGo°f AH°t. AS°t)} for-HgO, HgS, HgSO4, Hg2SO4, HgSO4?HgO, and HgSO4?2HgO was developed based on the experimental results. Prior to this study, only estimated data were available in the literature for the sulfates and oxysulfates at temperatures above 298K. A series of vapor pressure' stability diagrams were constructed from 473 to 973K with isobars of Hg(g), HgO(g), S2(g), and SO3(g). These diagrams were found to be significantly different than those available previously and do provide insight to the phase relations of importance during the thermal processing of Hg-containing wastes. The thermodynamic results were used to conduct a series of Gibbs energy minimization calculations for a thermal processor' afterburner system for the treatment of HgS-containing wastes. The retention of Hg in the discharge calcine was examined as a function of temperature and excess air. Hg was found to report to the calcine as HgSO4, Hg2SO4, or HgSO4 HgO depending on the process conditions, and Hg retention occurs at temperatures as high as 930K. The precipitation of Hg-containing phases from cooled afterburner discharge gas starts at approximately 900K and the cooling of the gas an additional 30K (to 870K) results in over 50% of the Hg being preCipitated as HgS04?HgO. It was also determined that for small amounts of Hg present in sulfide concentrates during roasting, the Hg will be retained as HgSO4 or HgSO4?HgO at temperatures as high as 870K.

Jan 1, 1996

By A. Andreas Hejja

Flow of slag and settling of matte in slag resistance electric furnaces are discussed in conjunction with furnace geometries, stirring action of the electrodes, buoyancy and electromagnetic effects. The rectangular electric furnace was regarded as a channel reactor and the mode of slag flow as a channel flow. The flow is affected both by buoyancy and electromagnetic forces, however the effect of electromagnetic forces is minimal. The flow velocity is made up of two components; (i) that developed by the action of the electrodes, and (ii) the bulk flow velocity determined by the smelting rate and the volume of the reactor. Slag samples were taken from various depths of the molten bath and were analyzed microscopically to determine the size and distribution of matte particles, The action of the electrodes was described by a simple mathematical formula indicating a balanced settling rate in the area of electrode action.

Jan 1, 1996

By Pier-Lorenzo Solari, Philippe Moisy, Michel Schlegel, Stephane Pellet-Rostaing, Eric Mendes, David Bengio, Richard Husar, Thomas Dumas

Ionic liquids (ILs) are molten salts composed of an organic cation that are liquid below 100 °C. They demonstrate unique physico-chemical properties such as good conductivity, negligible vapor pressure and non-flammability. As a consequence, they are often regarded as green solvents and could become an alternative to the use of both high-temperature molten salts and volatile organic solvents in rare-earth elements processing and recycling. The diversity of interactions existing in an ionic liquid allows the solubilization of both polar and apolar compounds. Moreover, coordinating functions on their composing ions can lead to stabilization of some species. For instance, in non-aqueous media, europium exists in the (II) oxidation state which is not stable in aqueous solutions. Understanding the mechanism of Eu(III) electrochemical reduction to Eu(II) and the stabilization of Eu(II) species in IL media could be of major interest for the development of innovative recycling processes. Using transient electrochemistry and UV-Vis spectroscopy we could get valuable information on the redox behavior of the Eu(III)/(II) couple in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([EMIm][NTf2]). Reduction of Eu(III) to Eu(II) and stability of Eu(II) was also studied thanks to a XAS-spectroelectrochemistry set up used to follow in situ the evolution of the XANES spectrum around the L3 edge of Eu during electrolysis.

Mar 1, 2018

By V. D. Tathavadkar

Chromite ore is of immense importance for the extraction of metallic chromium and chromium chemicals. The mineralogy and crystal structure of chromite phase are therefore important part of our investigation on the extraction chemistry of chromium species. In this investigation, we have studied the effect of the processing parameters, i.e., the temperature and the oxygen potential on the microstructure and composition of mineral phases formed in the Cr2O3 ?Al2O3 -FexOy -MgO system. In particular the importance of the spinodal decomposition reaction is emphasized in the extraction of chromium as sodium chromite and sodium chromate. Experiments were carried out in order to study the differences in the crystallography of different chromite minerals. Phase equilibria in natural chromite minerals were investigated by calcining chromite mineral in air, argon, and 5% hydrogen + argon atmospheres over a temperature range from 200 to 1200 °C. The effect of the oxygen partial pressure and temperature on the phase constituents of the calcined product has been discussed. The microstructural changes were examined using scanning electron microscope (SEM) and the changes in elemental composition in different phases were analysed by electron probe micro analyser (EPMA). The results obtained from EPMA studies were used to calculate lattice parameter of the spinel lattice, and these values were compared with the values obtained from X-Ray powder diffraction data. On the basis of the experimental data, the mechanism of the spinodal decomposition of complex spinel phases is described under the influence of oxygen partial pressure and temperature.

Jan 1, 2000

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 William Petruk

The capabilities of SEM/image analyzers for determining quantitative mineral data which have a bearing on extractive metallurgy have given applied mineralogy a new dimension. The capabilities include automatic mineral identification, unattended operation, search for rare minerals, and measurements of (1) mineral quantities, (2) grain and particle size distributions, (3) liberation characteristics of minerals in ground ores, and (4) mineral associations. Data on mineral quantities define the distributions of elements among minerals, provide background information on characteristics of the samples, and provide a data base for a mineral-materials balance. Size analysis data of the minerals in unbroken ores are used to predict the grind required to liberate minerals. Data on liberation analysis can be used in many ways. One application is to process the image analysis data for feed, concentrate and tails by a materials balancing technique to calculate the recovery of liberated and unliberated grains at each point in a circuit. The calculated recovery data define the behaviour of an ore in a concentrator, pilot plant or bench test, and indicate whether recovery improvements are possible and/or feasible for a particular ore.

Jan 1, 1991

By Ramana G. Reddy

Thermodynamic modeling and experimental study on impurity capacities and their distribution between mattes or metal and slags in smelting, converting and refining of non-ferrous metals was discussed. A brief review on the recent developments in copper smelting and converting is presented. The analysis showed that, copper smelting capacity increased by a factor of 10 since 60's, smelting rate increased by a factor of more than 5 and process fuel equivalent decreased by a factor of 2. A thermodynamic model for prediction of impurities capacities in slags and their distribution in mattes and slags was developed. The impurities capacities (i.e. sulfur and arsenic) of slags were calculated a priori with no adjustable parameters using the Reddy-Blander model. The capacities predictions were made in a wide range of matte and slag compositions, PSo, and temperatures in conditions pertaining to copper and lead industrial slags. The calculated results for sulfide and arsenate capacities are in good agreement with the available experimental and industrial copper and lead industrial slags data. The sulfide and arsenate capacities in copper slags (fayalite, ferrite and olivine) and lead slags are reviewed. The application of RB model predicted ratios of O2 and S2 partial pressures in industrial copper smelting processes are discussed. Application of this model for the prediction of Sb, Bi and other impurity capacities and their distribution ratios in mattes or metal and slags, in industrial smelting and refining processes is discussed.

Jan 1, 2003

By W. G. Davenport

Changes in copper extraction from 1960 till today are documented. The top ten changes have been: (a) replacement of reverberatory smelting by high intensity oxygen rich smelting (b) growth of the Outokumpu flash smelting to over 50% of the world's smelting capacity (c) successful development of single furnace coppermaking but only for low slag fall concentrates (d) replacement of the batch Peirce-Smith converter by continuous converting, but only in a few cases (e) increased SO2 capture throughout the industry, mainly-as sulfuric acid (f) development of low initiation temperature `big bight' Cs catalysts for treating the continuous high-SO2 strength gases from continuous smelting/converting (g) complete replacement of reverberatory anode scrap and cathode melting furnaces by the Asarco shaft furnace (h) adoption of stainless steel permanent cathodes and automated stripping technology for electrorefining and electrowinning (i) complete elimination of wire bar casting by continuous bar casting/rod rolling (j) development and adoption of extractants for turning weak impure leach solutions into strong pure electrolytes. It is postulated that the biggest possible change over the next 20 years would be complete replacement of smelting/converting by hydrometallurgical processing. However, this seems unlikely due to copper purity, precious metal recovery, and economic concerns. The increasing value of sulfuric acid to many copper companies gives chalcopyrite smelting/oxide-supergene leaching a nice synergy especially with the energy credits now coming from continuous smelters, and their acid plants.

Jan 1, 1999