Sponsored by: Jt. EPD/MDMD Synthesis, Control, and Analysis in Materials Processing Committee, EPD Process Fundamentals, Aqueous Processing, Copper, Nickel-Cobalt, Pyrometallurgy, Lead, Zinc, Tin Committees, MSD Thermodynamic & Phase Equilibria Committee
Program Organizers: R.G. Reddy, Department of Chemical and Metallurgical Engineering, University of Nevada, Reno NV 89557; S. Viswanathan, Oak Ridge National Lab., Oak Ridge, TN 37831-6083; J.C. Malas, Wright-Patterson AFB, OH 45433-6533
Monday, AM Room: A16-17
February 5, 1996 Location: Anaheim Convention Center
Session Chairpersons: R. G. Reddy, Department of Chemical and Metallurgical Engineering, University of Nevada, Reno NV 89557; E. J. Grimsey, Department of Mineral Engineering and Extractive Metallurgy, Western Australian School of Mines, Kalgoorlie, Western Australia 6430
8:30 am
SULFIDE CAPACITIES OF CaO-AlO1.5 AND CaO-FeO-SiO2 SLAGS: R. G. Reddy, W. Zhao, Department of Chemical and Metallurgical Engineering, University of Nevada, Reno, NV 89557
The sulfide capacities (Cs) of CaO-AlO1.5 melts were experimentally determined using encapsulation method at 1773 K. The Cs of CaO-AlO1.5 and CaO-FeO-SiO2 melts were calculated a priori using the Reddy-Blander model. The calculated Cs results are in very good agreement with the experimental data. The sulfur distribution ratio (sulfur in slag/sulfur in metal) in CaO-FeO-SiO2 slags as a function of slag composition was calculated. The results were used to explain the sulfur distribution in several industrial slag systems.
8:55 am
MODELING OF SULPHIDE CAPACITIES OF SOME SILICATE MELTS: R. Nilsson, Du Sichen, S. Seetharaman, Division of Theoretical Metallurgy, Royal Institute of Technology, S-100 44 Stockholm, Sweden
In the present work, an assessment of the sulphide capacities of a number of binary and ternary slag systems have been carried out in the light of this model. The model is based on the expression: Cs = exp (-[[Delta]]G[[ring]]/RT) o ao2-/fS2- where [[Delta]]G[[ring]] is the standard Gibbs energy change for the above reaction, ao2- is the activity of oxygen ions and fS2- is the activity coefficient of the sulphide ion in the slag. In the present model, the ratio (ao2-/fS2-) is optimized for the experimental data available in literature. The systems assessed are the binaries MnO-SiO2, CaO-SiO2, Al2O3-CaO, as well as the ternaries CaO-Al2O3-SiO2 and CaO-MnO-SiO2. In the case of all these systems, the experimental data available in literature are complemented by measurements carried out at the Division of Theoretical Metallurgy. The sulphide capacities of some FeO- containing binary and ternary slags are also examined. The potentiality of the model to estimate the sulphide capacities of complex slag systems from binary and ternary data is demonstrated.
9:20 am
REDUCTION OF MnO-FeO-SiO2 SLAGS BY CARBON-SATURATED LIQUID IRON: José R. de Oliveira, Jorge A. S. Tenório, Department of Metallurgical and Materials Engineering, University of São Paulo 05508, São Paulo, Brazil 05508
The aim of the present work was to investigate the reduction process of MnO-FeO-SiO2 slags by carbon-saturated liquid iron. The effect of the initial Mn content in the bath and also the effect of the initial SiO2 content were explored. The initial Mn content was in the range of 0 to 40 wt.% and the SiO2 content was in the range of 14 to 26 wt.%. The MnO content in the slag was kept constant at 40 wt%. The tests were performed in laboratory apparatus. Samples of slags and bath were taken. In the first five minutes a very strong reduction of the FeO was observed. This first step promoted a MnO-SiO2 enrichment of the slag and formation of CO bubbles, which increased the slag level. The increase of Mn and SiO2 decreased the MnO reduction rate.
9:55 am
REDUCTION OF MnO PELLETS BY CARBON-SATURATED LIQUID IRON: José R. de Oliveira, Jorge A. S. Tenório, Department of Metallurgical and Materials Engineering, University of São Paulo, São Paulo, Brazil 05508
The goal of this work was to investigate the reduction process of MnO pellets by carbon-saturated liquid iron. The experiments were performed in a laboratory apparatus. The tests were performed at 1500 and 1600[[ring]]C. The initial Mn content in the bath was in the range of 0 to 40wt%. Two sizes of pellets were tested. The reaction time was observed by the evolution of CO.
10:20 am BREAK
10:30 am
REMOVAL OF As AND Sb FROM MOLTEN COPPER BY Na2CO3 FLUXING: Baozhong Zhao, Nickolas J. Themelis, Deparment of Chemical Engineering, Materials Science and Mining Engineering, Columbia University, New York, NY 10027
Research to-date has shown that fluxing with soda ash (Na2CO3) can remove As and Sb from molten copper at the rate of As>Sb, but is relatively ineffective in removing Bi. Oxygen in the copper is essential for soda ash reactions. If the oxygen content in the copper is reduced after soda ash fluxing, the impurity in the soda ash slag can return to the copper. In this paper, the influences of various factors, such as the initial oxygen content in the copper, the flow rate of carrier gas, the soda ash feed rate, and the effects of soda ash fluxing by surface addition and injection, on the rate of impurity removal are discussed. In the light of experimental results, a mathematical model was developed to describe the impurity removal phenomena.
10:55 am
DISTRIBUTION OF Se AND Te BETWEEN MATTE AND SLAG IN NICKEL SULFIDE SMELTING: N. Choi, W. D. Cho, Department of Metallurgical Engineering, University of Utah, Salt Lake City, UT 84112
The distribution behavior of selenium and tellurium in nickel sulfide smelting was investigated in the temperature range of 1250-1300[[ring]]C under an inert gas atmosphere and various oxygen partial pressures. The distribution coefficients of selenium and tellurium between nickel-copper-iron matte and silica-saturated iron silicate slag were determined in terms of matte and slag compositions, temperatue, and oxygen partial pressure. The effect of slag additives such as CaO, MgO, and Al2O3 on the distribution coefficients of these elements was also investigated. It was observed that the distribution coefficients of selenium and tellurium increased with increasing matte grade and temperature. The solubility of selenium and tellurium in the slag decreased with increasing partial pressure of oxygen. The distribution coefficients of selenium and tellurium increased with the amount of CaO and MgO. Tellurium distribution coefficients also increased by the addition of Al2O3. Meanwhile, the addition of Al2O3 decreased the distribution coefficients of selenium at high-matte grade.
11:20 am
KINETICS OF REACTIONS BETWEEN IRON OXIDES AND LIQUID IRON-CARBON ALLOYS: Marcelo B. Mourão, Cássio A. Rodriguez , Ricardo S. Maltez, Department of Metallurgical and Materials Engineering, Politechnic School, University of São Paulo, 05508-900 São Paulo, SP, Brazil
An experimental investigation was carried out to study the rates of reduction
of pellets containing iron oxides by carbon dissolved in liquid iron, at
temperatures ranging from 1720 K to 1973 K. Several different pellet types were
employed; the materials used in the pellet's manufacture were pure hematite,
two kinds of commercial iron ores, and mixtures hematite/silica and
hematite/lime. Reaction times were determined employing the constant volume
pressure increase technique (CVPI). It has been observed that the reaction rate
increases as the temperature and the pellet's specific area increases, and as
the pellet's size decreases. The reaction rate is also affected by the ore type
and by the kind of compound formed between hematite and other oxide; pellets
containing calcium oxide react faster than the ones containing silicon oxide.
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