Behavior Of Minor Elements Research Articles

Thermodynamic Modeling of Elemental Distributions of Trace Elements in Non-ferrous Iron Residue Hydrogen Reduction

Every year millions of tons of iron residue are generated as a by-product of zinc production. Stabilized landfilled iron residue contains recoverable metals that could be valorized with further processing. Pyrometallurgical processing allows the recovery of valuable metals while simultaneously producing a clean slag that can then be further utilized. A thermodynamic model was developed with FactSage version 8.0. The focus was on minor element behavior and distribution of elements between phases. Calculations were performed at 1200–1400°C and pressure of 1 atm with both pure H2 and H2-Ar mixtures used as a reductant. Also, the concentrations of Pb and Zn in the input were varied. The results showed that a liquid alloy phase forms consisting mostly of either Cu, As and Pb or Fe, As and Cu. It was noted that a higher Ar total gas amount in reduction decreased the mass fraction of the liquid alloy and increased the evaporation of elements into fume dust. S, Bi, Pb, Ge and Zn were observed to evaporate fully, while As, In, Sb and Ag evaporated only partially. The results need to be verified experimentally.

Analytical and numerical simulations for the kinetics of phase separation in iron (Fe–Cr–X (X=Mo, Cu)) based on ternary alloys

In this paper, we investigate the physical behavior of the basic elements that related to phase decomposition in ternary alloys of (Fe–Cr–Mo) and (Fe–Cr–Cu) according to analytical and approximate simulation. We study the dynamic of the separation phase for the ternary alloys of iron. The dynamical process of this separation has been described in a mathematical model called the Cahn–Hilliard equation. The minor element behavior in the process has been described by the Cahn–Hilliard equation. It describes the process of phase separation for two components of a binary fluid in ternary alloys of (Fe–Cr–Mo) and (Fe–Cr–Cu). We implement a modified auxiliary equation method and the cubic B-spline scheme on this mathematical model to show the dynamical process of phase separation and the concentration of one of two components in a system. We try obtaining the solitary and approximate solutions of this model to show the relation between the components in this phase. We discuss our solutions in view of a Stefan, Thomas-Windle, and Navier–Stokes models. Whereas, these models describe the motion of viscous fluid substance.

Behavior of Pt, Pd, and Au During Crystallization of Cu-Rich Magmatic Sulfide Minerals

Abstract The method of quasi-equilibrium directed crystallization was used for experimental modeling of the behavior of Pt, Pd, and Au in the presence of As, Te, Bi, and Sn during the fractional solidification of Cu-rich sulfide magma. Our experimental melt contained (in mol.%): Fe 33.20, Cu 16.55, S 50.03, Pt 0.03, Pd 0.02, Au 0.02, As 0.02, Bi 0.03, Te 0.02, and Sn 0.08, which is similar in composition to the massive cubanite ores from the platinum-copper-nickel deposits of the Noril9sk group. During crystallization, base metal sulfides [pyrrhotite solid solution ( Po ss ) and high-temperature cubanite (isocubanite, Icb )] crystallized successively from the melt. The constructed curves show variations in the concentrations of Fe, Cu, and S along the ingot. Based on these data, we calculated melt composition during crystallization and determined the distribution coefficients of components between Po ss or Icb and the melt. The behavior of minor elements in this process was studied. The data show that the content of minor elements in Po ss is below the detection limit of electron microprobe analysis. Tin dissolves in isocubanite, whereas Pt, Pd, Au, As, Bi, and Te are present in the matrix as microinclusions. These elements form their own microphases: kotulskite–sobolevskite (PdBi x Te 1– x ) and moncheite–insizwaite Pt(Te x Bi 1– x ) 2 solid solutions, cooperite (Pt,Pd)S, sperrylite Pt(As,S) 2 , froodite PdBi 2– x , bismuthinite Bi 2 S 3– x , Au, lisiguangite CuPtBiS 3 , and unnamed PtBiS 3– x . Also present are drop-shaped eutectic-like inclusions in which PdBi x Te 1– x is the matrix containing micron-sized inclusions of Au and PdBi 2– x . The constructed crystallization history of the experimental sample demonstrates the behavior of both major and minor elements in each of the zones. A probable mechanism of formation of monophase and polyphase inclusions is proposed. The mineral forms of Pt, Pd, and Au phases in the samples and their morphology are comparable to the typical natural types in massive Cu-rich sulfide ores from the Noril9sk deposits.

Ferric sulphate/chloride leaching of zinc and minor elements from a sphalerite concentrate

Atmospheric leaching of a sphalerite concentrate in sulphate and chloride media was performed and the effect of several variables, such as solid/liquid ratio and oxidant (Fe(III)) concentration were investigated. The behaviour of minor elements, such as Cu, In, As, Sb, Bi, Sn and Pb, was also studied under different conditions. The results showed that using a solid/liquid ratio of 5% (w/v) it was possible to leach 95% of zinc after 2 h, with a solution of 0.5 M H 2SO 4 and Fe 2(SO 4) 3 at 80 °C. The minor elements As, Sb and Bi were also completely leached whereas copper leaching was favoured by the use of chloride medium. The oxidation of Fe(II) during the leaching tests was studied and an improvement of 20% zinc extraction was observed in an oxygenated system. Cross-current leach tests using two/three stages and a solid/liquid ratio of 10% (w/v) were performed to achieve 90% of zinc extraction. The electron microprobe analysis of the leaching residues showed no change on the sphalerite composition after the leaching, which indicates that the leaching of sphalerite involves the break down of the sulphide structure.

Petrology and geochemistry of the fine‐grained, unbrecciated diogenite Northwest Africa 4215

Abstract— We report on the petrology and geochemistry of Northwest Africa (NWA) 4215, an unbrecciated diogenite recovered in the Sahara. This single stone, weighing 46.4 g, displays a wellpreserved cumulative texture. It consists of zoned xenomorphic orthopyroxene grains on the order of 500 μm in size, along with a few large chromite crystals (<5 vol%, up to 3 mm). Accessory olivine and scarce diopside grains occur within the groundmass, usually around the chromite crystals. Minor phases are cristobalite, troilite, and metal. Unlike other diogenites, orthopyroxenes (En76.2Wo1.1Fs22.7 to En68.6Wo5.5Fs25.9), olivines (Fo76 to Fo71), and chromites (Mg# = 14.3 44.0, Cr# = 42.2–86.5) are chemically zoned. The minor element behavior in orthopyroxenes and the intricate chemical profiles obtained in chromites indicate that the zonings do not mirror the evolution of the parental melt. We suggest that they resulted from reaction of the crystals with intercumulus melt. In order to preserve the observed zoning profiles, NWA 4215 clearly cooled significantly faster than other diogenites. Indeed, the cooling rate determined from the diffusion of Cr in olivine abutting chromite is in the order of 10–50 °C/a, suggesting that NWA 4215 formed within a small, shallow intrusion.The bulk composition of NWA 4215 has been determined for major and trace elements. This meteorite is weathered and its fractures are filled with calcite, limonite, and gypsum, typical of hot desert alteration. In particular, the FeO, CaO abundances and most of the trace element concentrations (Sr, Ba, Pb, and REE among others) are high and indicate a significant contribution from the secondary minerals. To remove the terrestrial contribution, we have leached with HCl a subsample of the meteorite. The residue, made essentially of orthopyroxene and chromite, has similar major and trace element abundances to diogenites as shown by the shape of its REE pattern or by its high Al/Ga ratio. The connection of NWA 4215 with diogenites is confirmed by its O‐isotopic composition (δ17O = 1.431 ± 0.102‰, δ18O = 3.203 ± 0.205‰, Δ17O = −0.248 ± 0.005‰).

Ｃｕ‐Ｆｅマットと銅の２液相分離範囲における銀の活量

Silver activity in the immiscible region between the molten copper and Cu - Fe matte of the Cu - Fe - S system was measured by applying a double Knudsen cell - mass spectrometric method at 1,473 K for analyzing the behavior of minor elements in a copper smelting process. The silver distribution between the two phases in the miscibility gap was also determined to find the relationship of the silver activity and composition in both the matte and copper phases with a quenching technique at the same experimental temperature. The following results have been obtained in the present study. The distribution coefficient of silver between the matte and copper phases, which is defined by {% Ag in matte} / [%Ag in metal] decreases from 0.4 at the iron free Cu - Cu2S immiscible region to 0.29 at the composition of iron saturation with increasing iron content. The activity coefficient of silver at infinite dilution in the matte, γoAg' changes from 9.9 in the Cu2S phase to 16 at γ - iron saturation in the Cu - Fe matte by addition of iron while the value of 3.3 for γoAg in the metal phase equilibrated with the matte phase is kept at almost constant. The value of 0.22 is obtained for eFeAg in molten copper by using the activity values in the copper phase combined with the reported values of eSAg in molten copper and γoAg in the Cu - Ag binary system. It is understood by the value of eFeAg obtained in the present study that the quite small change of γoAg is observed with increasing iron content in the copper phase of the Cu - Fe - S system. γoAgS0.5 in the matte phase is estimated from the distribution ratio of silver between the two phases combined with γoAg in the metal phase and ρS2 over the two phase region by assuming the formation of AgS0.5 in the matte phase. The obtained value for γoAgS0.5 changes from 0.81 in the iron free matte into 0.96 in the iron saturated matte, which exhibits nearly ideal behavior.

Distribution of Minor Elements between MgO Saturated FeO<I><SUB>x</SUB></I>–MgO–SiO<SUB>2</SUB> or FeO<I><SUB>x</SUB></I>–CaO–MgO–SiO<SUB>2</SUB> Slag and Nickel Alloy

The distribution behavior of minor elements between the nickel based alloy and MgO saturated FeO x -MgO-SiO 2 or FeO x -CaO-MgO-SiO 2 slag was investigated at 1673, 1773 and 1873 K under controlled oxygen partial pressure over the range from 10 -6 to 10 - 10 in order to obtain fundamental information related to nickel smelting. The distribution ratios of minor elements, which is defined by L s/m X =(mass%X in slag)/[mass%X in alloy] for phosphorus, iron, cobalt, copper and sulfur are higher than that for nickel while the ratio for antimony is lower. Base on the slope of the linear relationship between the logarithmic distribution ratio and oxygen partial pressure, the predominant species dissolved in the slag are evaluated to be of the forms PO 2.5 , CoO, CuO 0.5 and SbO 1.5 , respectively. It is found that the addition of CaO depresses the dissolution of copper and cobalt in the slag while that of phosphorus and antimony is enhanced. The activity coefficients of CuO 0.5 and CoO in the MgO saturated FeO x -MgO-SiO 2 slag at 1773 K are estimated to be 7 and 2 respectively.

Effects of CaO, Al2O3, and MgO additions on the copper solubility, ferric/ferrous ratio, and minor-element behavior of iron-silicate slags

The effects of CaO, Al2O3, and MgO additions, singly or in combination, on the copper solubility, the Fe3+/Fe2+ ratio in slag, and on the minor-element behavior of silica-saturated iron silicate slags were examined at 1250 °C and a p O2 of 10−12 to 10−6 atm. The results indicated that copper solubility in slag was lowered with the addition of CaO, MgO, and Al2O3, in decreasing order. The Fe3+/Fe2+ ratio in the slag decreased with the additions, but this effect was smaller at lower oxygen potentials. The presence of small amounts (about 4 pct) of CaO, Al2O3, and MgO in the slag resulted in increased absorption of Bi and Sb into molten copper, but had a smaller effect at large additions (about 8 to 11 pct). The distribution behavior of Pb was a function of oxygen partial pressure, which indicates the oxidic dissolution of Pb in the slag as PbO, while the behavior of Bi, Sb, and As was found to be independent of oxygen potential, supporting the atomic (neutral) dissolution hypothesis of these elements in the slag. The distribution behavior of Pb and As was not significantly affected by the additions. The activity coefficients of Bi and Sb in the slags were determined to be as follows: (1) for no addition, γ Bi=40 and γ Sb=0.4; (2) for small additions (about 4.4 pct), γ Bi=70 to 85 and γ Sb=0.8; and (3) for large additions (about 8 to 11 pct), γ Bi=60 to 75 and γ Sb=0.5 to 0.7.

Kinetic modeling of minor element behavior in copper converting

The kinetics of minor element removal has been included in an overall model of the Peirce-Smith converter. Mass transfer between the condensed phases and to the gas has been considered. The model is able to predict the distribution of the minor elements fairly well but is limited by the scarcity of thermodynamic and kinetic data. It has been determined that the factors that increase oxygen efficiency, in particular gas velocity and tuyere submergence, tend to increase the proportion of the minor elements reporting to the dust. The reduction of the gas volume flow through the converter associated with oxygen enrichment does tend to reduce the minor element content in the dust. However, this effect may be offset by the increased temperature. Increasing temperature also increases the minor element content of the blister copper produced.

Minor-element behavior and iron partition during the cleaning of copper converter slag under reducing conditions

A mathematical model has been developed to describe the reduction process and the minor-element behavior during the cleaning of copper converter slag under equilibrium conditions. The results of simulation show that large fractions of Pb, Bi, Sb and As, but little of Zn, are absorbed into the recovered copper phase. Generally, the distribution behavior of minor elements is affected by temperature and CO partial pressure, but not by the initial amounts of these elements in the slag or by the activity of FeO. There is a limit to the recovery of copper by reducing Cu 2O from the slag because iron oxides are also reduced at low oxygen potentials to form a solid copper-iron alloy which is impossible to separate from the slag. The limit was 90% recovery of copper (0.3% Cu in slag) at 1250 °C for the converter slag of typical composition used in this study. The predicted results were compared with the actual observed data from pilot plant operation in which pulverized coal was used as a reductant. Consistent trends between the two cases were obtained.

Minor-Element Behavior and Iron Partition During the Cleaning of Copper Converter Slag Under Reducing Conditions

A mathematical model has been developed to describe the reduction process and the minor-element behavior during the cleaning of copper converter slag under equilibrium conditions. The results of simulation show that large fractions of Pb, Bi, Sb and As, but little of Zn, are absorbed into the recovered copper phase. Generally, the distribution behavior of minor elements is affected by temperature and CO partial pressure, but not by the initial amounts of these elements in the slag or by the activity of FeO. There is a limit to the recovery of copper by reducing Cu2O from the slag because iron oxides are also reduced at low oxygen potentials to form a solid copper-iron alloy which is impossible to separate from the slag. The limit was 90% recovery of copper (0.3% Cu in slag) at 1250°C for the converter slag of typical composition used in this study. The predicted results were compared with the actual observed data from pilot plant operation in which pulverized coal was used as a reductant. Consistent trends between the two cases were obtained. © 1997. Published by Elsevier Science Ltd. All rights reservedRésuméOn a développé un modéle mathématique décrivant le procédé de réduction et le comportement d' élément mineur lors du nettoyage du laitier de convertisseur du cuivre sous des conditions d'équilibre. Les résultats de la simulation montrent que de grandes quantités de Pb, de Bi, de Sb et d'As, mais peu de Zn, sont absorbées dans la phase de cuivre récupéré. Généralement, le comportement de distribution des éléments mineurs est affecté par la température et par la pression partielle du CO, mais non pas par les quantités initiales de ces éléments dans le laitier ni par l'activité du FeO. Il y a une limite à la récupération de cuivre par réduction du Cu2O à partir du laitier parce que les oxydes de fer sont aussi réduits à de faibles potentials d'oxygéne, formant un alliage solide cuivre-fer qu'il est impossible de séparer du laitier. La limite de récupération était de 90% ddu cuivre (0.3% Cu dans le laitier) à 1250°C pour le laitier de convertisseur de composition typique utilisé dans cette étude. On a comparé les résultats prédits avec les données actuelles observées lors de l'opération d'une usine pilote dans laquelle du charbon pulvérisé était utilisé comme agent réducteur. On a obtenu des tendances concordantes entre les deux cas.

Minor-Element Behavior and Iron Partition During the Cleaning of Copper Converter Slag Under Reducing Conditions

Minor-Element Behavior and Iron Partition During the Cleaning of Copper Converter Slag Under Reducing Conditions

Kinetic Studies of Copper Flash Smelting Furnace and Improvements of its Operation in the Smelters in Japan

Research activities on the smelting reaction in the Outokumpu flash furnace and its operation have been reviewed. First, the oxidation kinetics of copper concentrate particles and the ignition phenomena were discussed. Second, the mathematical modeling and experimental investigation on the progress of smelting reactions in the shaft of the furnace were summarized. Dust generation and behavior of minor elements in the shaft were also important. Third, it was found from the oxygen potential in matte and slag in the settler that most of the smelting reactions are completed in the reaction shaft or in the settler just beneath the shaft. The use of powder coke results in the formation of reduction atmosphere on the slag surface in the settler, and its effect on the operation was discussed. The residence time distribution of slag in the settler is also an important factor of the operation of the flash smelting furnace.

Production of palladium powder by reduction of palladium diamino-chloride by sodium oxalate : G.N. Shrivin et al, (Krasnoyarsk Institute of Non-Ferrous Metals, USSR), Izvestia V U Z Tvest, Metall, No 4, 1990, 51–54. In Russian

Section 2.1.1 covers the basic thermodynamic and kinetic principles involved in producing copper by high-temperature smelting processes. The section starts with the description of the stability of copper compounds relevant to the pyrometallurgical production of copper from the minerals and how it relates to the development and operation of different production methods. Next, the thermodynamic principles involved in the mattemaking and converting steps of copper smelting, including the behavior of minor elements and their distribution into various phases during these steps. Finally, the rate processes relevant to various subprocesses of copper smelting, such as the oxidation of concentrate and intermediate compounds as well as the volatilization of minor elements during the converting step, are discussed.Section 2.1.2 covers the current technologies used for pyrometallurgical production of copper. The section starts with the description of the mattemaking processes, grouped into suspension smelting and bath smelting, followed by converting processes which are similarly classified into two groups. The Mitsubishi continuous copper smelting process that combines the matte smelting and converting steps into one continuous coupled operation is then discussed. Finally, some observation on the industry trends for copper production is presented.The use and degradation of refractory linings in copper furnaces are discussed in Section 2.1.3. Magnesia-chrome bricks are widely used to line copper furnaces, despite the potential risk for the formation of hexavalent Cr under specific conditions, typically in the presence of alkali or alkaline earth oxides. Which combination of chemical, thermal, and mechanical degradation mechanisms is dominant depends on many factors such as the furnace type, the lining design, including the selection of the refractory type, and the process conditions. This overview concludes with refractory selection and use on the industrial level, including the waste and recycling management of spent refractories.

Mathematical modeling of sulfide flash smelting process: Part III. Volatilization of minor elements

The mathematical model described in Part I[14] was extended to include the minor element behavior inside a flash-furnace shaft during flash smelting of copper concentrate. The volatilization of As, Sb, Bi, and Pb was computed, and experiments were carried out for Sb and Pb in a laboratory flash furnace. Satisfactory agreement between the predicted and measured results was obtained for antimony and lead. From the computational results, the behavior of each minor element was predicted for various target matte grades. The model predictions show that the elimination of As and Bi to the gas phase increases sharply at about 0.3 m from the burner; however, that of the Sb increases gradually along the flash-furnace shaft, and that of lead occurs suddenly at about 0.6 m from the burner. The predicted results also show that the elimination increases for Bi and Pb as the target matte grade increases; however, it is relatively independent of the target matte grade between 50 and 60 pet Cu for As and Sb. At higher target matte grades above 60 pet Cu, the elimination of As and Sb decreases as matte grade increases.

Mathematical modeling of minor-element behavior in flash smelting of copper concentrates and flash converting of copper mattes

A mathematical model has been developed to describe the behavior of minor elements during flash smelting and flash converting. The model incorporates equations describing volatilization of minor elements from the molten particles and distribution of these elements between the molten phases in the settler. The basic premise of the volatilization model is that at the surface of the molten particle, the partial pressures of the minor-element species are those at equilibrium. Transport of the minor-element species to the gas then is described by external mass transfer. Good agreement has been obtained between observed and predicted behaviors. The effects of oxygen enrichment, matte grade, and wall temperature, as well as the bath temperature, on minor-element behavior have been elucidated.

The Noranda Process and Different Matte Grades

Since 1975, the Noranda Process reactor at the Home smelter has generally operated at matte grades of 70–74% Cu. This paper reports on tests which were carried out to evaluate the performance of the reactor at lower matte grades. Reactor operation at matte grades down to 55% Cu was found to be as stable and predictable as operation at higher matte grades. This paper discusses operating results, including metallurgical data such as fuel and oxygen requirements, slag and matte characteristics and information on the behavior of minor elements.

Crystal/liquid partitioning in augite: effects of cooling rate

The partitioning of major and minor elements between augite and melt was determined as a function of cooling rate for two high-titanium basalt compositions. The results of this study of lunar rock systems 10017 and 75055 were compared with the results of other kinetic studies of augite-liquid partitioning in other rock systems. It was found that the partitioning of major elements (i.e., Ca, Fe, Mg) is essentially rate independent and is insensitive to bulk rock composition and to the nature and order of appearance of coexisting phases for cooling rates of less than 100°C/hr. The partitioning behavior of minor elements (i.e., Al, Cr, Ti) for the same range of cooling rates is complex, being dependent on cooling rate and bulk rock composition. Consideration of these factors is important when augite chemistry and/or partitioning behavior are used in modeling certain magmatic processes or in estimating the thermal history of basaltic rocks.

Thermodynamics of Copper Matte Converting: Part II. Distribution of Au, Ag, Pb, Zn, Ni, Se, Te, Bi, Sb and As Between Copper, Matte and Slag in the Noranda Process

The solubility of minor elements in fayalitic slags was assessed thermodynamically assuming exclusively oxidic dissolution for Pb, Zn and Ni, metallic dissolution for Au and Ag, molecular and monatomic dissolution for Se and Te, and monatomic dissolution for Bi, Sb and As. Based on these assumptions as well as the thermochemical data in the literature, an analytical method was developed to calculate the distribution equilibria of minor elements between copper, matte and slag phases. As an example of the application, the method was demonstrated for the analysis of behavior of minor elements in the Noranda Process producing metallic copper or high grade matte. The distribution of minor elements was expressed in terms of concentration ratios of an element for copper/matte, copper/slag and matte/slag phases. Using the concentration ratios and also formulae compensating for mechanical suspension, apparent distribution coefficients of the minor elements in the actual process were calculated as a function of the process parameters: temperature, partial pressure of SO2, magnetite activity and matte grade. An excellent agreement was observed between the calculated and observed data, thus providing logical basis for interpreting operating data of the Noranda Process. The behavior of minor elements under various operating conditions can also be predicted by the present model.

Copper solubility in FeO−Fe2O3−SiO2−Al2O3 slag and distribution equilibria of Pb, Bi, Sb and As between slag and metallic copper

The solubility of copper in silica-unsaturated fayalite slags containing an average of about 8 pct Al2O3 was measured by equilibrating the slag with metallic copper at 1200 and 1300°C under CO−CO2 atmospheres with oxygen potentials in the rangepO2=10−6 to 10−11 at. The copper solubility, which was found to be dependent upon the oxygen potential, was expressed in terms of the Fe/SiO2 ratio, temperature and activity of CuO0.5. The distribution of Pb, Bi, Sb and As between copper and slag was measured concurrently by doping the metallic copper. The distribution coefficient was defined by (mole fractionX in metal)/(mole fractionX in slag) assuming the FeO−FeO1.5−SiO2−AlO1.5−CuO0.5 system slag. The distribution coefficient for lead was found to be a function of the oxygen potential, and a PbO activity in the slag of 0.07±0.01 was measured over the range of 1200 to 1300°C. Dissolution of Bi, Sb and As in the slag was found to be independent of the oxygen potential suggesting atomic rather than oxidic dissolution. The observed distribution coefficient for Bi and Sb was 30. The observed distribution coefficient for As was 300, but this is subject to error up to one order of magnitude due to analytical uncertainty of slag. The data are useful in analyzing minor element behavior in copper smelting processes.