Sponsored by: EPD Pyrometallurgy Committee
Program Organizer: Jerome P. Downey, Hazen Research, Inc., Golden, CO 80403; Ed Mounsey, Ausmelt Limited, 2/13 Kitchen Road, Dandenong, Victoria 3175 Australia
Wednesday, AM Room: A16-17
February 7, 1996 Location: Anaheim Convention Center
Session Chairmen: J. D. McCain, Vice President, Operations, Magma Metals Company, San Manuel Division, PO Box M, San Manuel, AZ 85631; H. Y. Sohn, Professor, Department of Metallurgical Engineering, The University of Utah, 412 Browning Building, Salt Lake City, UT 84112
8:30 am
OXIDATION OF FeCl3 USING RADICALS PRODUCED IN A NON-EQUILIBRIUM OXYGEN PLASMA: Quiling Yu, D. C. Lynch, Arizona Materials Laboratory, Dept. of Materials Science & Engineering, University of Arizona, Tucson, AZ 85721
FeCl3 particulate was reacted with radicals produced in an oxygen plasma at pressures between 1 to 20 Torr. Reaction between the iron chloride and the gas phase occurred at temperatures between 66 and 226[[ring]]C. The experimental evidence indicates that the extent of reaction is independent of the temperature of the particulate, but is a function of the square root of the power absorbed by the plasma divided by the plasma pressure. This parameter is a reflection of the average energy of free electrons in the plasma. Electron energy establishes the collision cross section for inelastic collisions, collisions which are responsible for producing radicals such as monatomic oxygen. The radicals react with surface material with the maximum amount of FeCl3 reacted being 67 wt%.
8:55 am
THERMOGRAVIMETRIC ANALYSIS OF THE REDUCTION OF MIXED OXIDES: Dhiren K. Panda, Kent D. Peaslee, David G. C. Robertson, Generic Mineral Technology Center for Pyrometallurgy, University of Missouri-Rolla, 215 Fulton Hall, Rolla, MO 65401-0249
Several pyrometallurgical processes for the treatment of waste oxides involve the addition of charge material in the form of pellets containing carbon (coko) as the reductant. Waste oxide materials usually contain a mixture of several oxides, such as iron oxide(s), zinc oxide, and lead oxide. Results of TGA experiments are presented in this paper highlighting the complex reduction reactions (of various oxides) occurring within the pellets during the heating cycle. These experiments were carried out with zinc retort residues from old zinc production sites in the Missouri-Oklahoma-Kansas tri-state areas. This material contains oxides of iron, lead, and zinc with carbon content as high as 30%.
9:20 am
COPPER LOSSES IN COPPER SMELTING SLAGS: R. Sridhar, J. M. Toguri, S. Simeonov, Department of Metallurgy and Materials Science, University of Toronto, 184 College Street, Toronto, Ontario, Canada M5S 1A4
A relationship between copper in slag and copper in matte during copper sulfide smelting has been derived using industrial data from 40 plants employing blast furnaces, reverberatory furnaces, flash furnaces, and Mitsubishi smelting furnaces, together with the available thermodynamic equilibrium data for Cu-Fe-S-O, FeO-SiO2, and Cu-Fe-S systems and laboratory slag-matte equilibrium information. A "Copper Smelting Diagram" showing oxygen potential, sulfur potential, copper, magnetite, and sulfur contents in slag during the smelting of different grades of copper mattes is developed. The data presented can be used to determine entrained copper losses in slag. The dissolved sulfur content of slag was derived using calculated matte entrainment and the corresponding plant data for sulfur content of slag. The sulfur content thus derived corresponded closely to the experimental determined sulfide capacity of fayalite slags. The review of available and derived information suggest that there is no need to assume the presence of dissolved copper sulfide species in industrial slags. The existing equilibrium data which relate copper content of slag to oxygen potential adequately describe the copper losses in industrial slags.
9:45 am BREAK
10:15 am
COBALT EQUILIBRIUM DISTRIBUTION BETWEEN NICKEL-COPPER MATTE AND FAYALITE SLAGS: S. Simeonov, R. Sridhar, J. M. Toguri, Department of Metallurgy and Materials Science, University of Toronto, 184 College Street, Toronto, Ontario, Canada M5S 1A4
In recent years, the interest in the understanding of cobalt losses in nickel-copper smelting and converting has increased due to higher cobalt prices and the need for better cobalt recovery. Knowledge of the thermodynamic behaviour of cobalt in pyrometallurgical smelting and converting stages of nickel processing is essential to understand the behaviour of cobalt and to develop or modify processing steps to increase the cobalt recovery, which averages only about 50% in present day practice. A literature review indicates that only limited data are available under controlled oxygen and sulphur potentials corresponding to that encountered in the plant. The purpose of this study is to obtain such thermodynamic data for cobalt equilibrium distribution between nickel-copper matte and fayalite type slags. Cobalt equilibrium distribution measurements between fayalite slags and nickel copper matte at specific oxygen and sulphur pressures were carried out in the temperature range 1473 to 1623 K. In the actual operation, MgO is inevitable, because of the erosion of refractory. It is therefore of practical importance to also know how MgO addition to fayalite based slags influences cobalt behaviour.
10:40 am
FLOW AND SETTLING PHENOMENA IN MATTE SMELTING ELECTRIC FURNACES: A. Andreas Hejja, R. Hurman Eric, School of Process and Materials Engineering, Branch of Extractive Metallurgy, University of the Witwatersrand, Johannesburg, Private Bag 3, WITS 2050, South Africa
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 (2) 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.
11:05 am
WETTING BEHAVIOR AND INTERFACIAL REACTION BETWEEN FAYALITE SLAG AND MgO: H. Fukuyama, J. Donald, J. M. Toguri, Department of Metallurgy and Materials Science, University of Toronto, 184 College Street, Toronto, Ontario, Canada M5S 1A4
Extension of refractory life is of great interest in the copper and nickel
industry. In pyrometallurgical processes, infiltration of slag melts into
refractory materials affects the thermal and mechanical properties of the
bricks and it may lead to early failure. The height of infiltration of the
melts is generally governed by the surface tension of the melts and the contact
angle between the melts and the bricks. MgO is a main component of commercial
refractories, constituting between 30 and 98 percent of the brick. There is
very little information regarding the interfacial phenomena between this
refractory material and slag. Thus, in the present work, the sessile drop
technique was employed to investigate the wetting behavior of single crystal
MgO by the fayalite type slag melts. This provided the basic data for the
infiltration phenomena of commercial bricks. The reactions at the interface
between the melts and the MgO were examined by Electron Probe Microanalysis.
From these results, phase relationships between the slag and the MgO were
determined. The interdiffusivity of Fe and Mg in Magnesiowustite was also
determined.
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