Physical and mathematical modeling of pyrometallurgical channel reactors with bottom gas injection: Residence time distr
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INTRODUCTION
MANY smelting and molten-metal refining processes are characterized by slag/metal (or matte) reactions. The slag/metal mass transfer is an important factor in enhancing these processes. This is true of both ferrous and nonferrous processes. Processes using tonnage oxygen, both as an oxidant and mixing medium, have been developed to ensure good slag/metal mixing. The ferrous processes were the first to adopt this technology, leading to the development of such processes as basic oxygen furnace (BOF) and (Q-BOP) steelmaking. The nonferrous industry is just beginning to capitalize on the potential of this technology.t1-4] The first nonferrous process to do so is the Queneau-Schuhmann oxygen process (QSOP), which uses submerged injection of tonnage oxygen. At present, there is great emphasis on the development of continuous metal extraction and refining processes. Of these, countercurrent processes seem to have the most potential in terms of process control and efficiency of refining. In the ideal operation of such a system for metal refining, plug flow should be attained in the horizontal direction and local equilibrium in the vertical direction. This would allow transfer of impurities from metal or matte to slag at a high rate and still would maintain the concentration gradients along the reactor that are required for efficient operation. Top blowing over a channel reactor, I5-91as in the WORCRA process, showed that this goal can be approached. More recently, bottom gas injection into a channel reactor has been applied to QSL leadmaking U~ and the Hismelt process for steelmaking, t~tj Preliminary indications are that this goal is better achieved by bottom gas injection. KUMAR M. IYER, Graduate Student, is with the Department of Metallurgical Engineering, University of Utah. H.Y. SOHN, Professor, is with the Department of Metallurgical Engineering, University of Utah, Salt Lake City, UT 84112-1183. Manuscript submitted February 2, 1993. METALLURGICAL AND MATERIALS TRANSACTIONS B
The Queneau-Schuhmann (QS) reactor is a long, circular, cylindrical reactor lying on its side and inclined at an angle of 1 deg to the horizontal. 121 Flash burners in the roof of the vessel serve to partially smelt the ore and inject fluxes. In the reactor, the matte/metal and slag are in countercurrent flow, and tonnage oxygen is bottom blown into the reactor using the Savard-Lee injectors. The bottom injection serves to stir the bath, thus mixing the matte/metal and slag, and to complete the smelting. There is a staged control of the oxygen partial pressure along the length of the reactor, by the use of shallow suspended baffles, making it possible to make metal at one end while cleaning slag at the other. The slag cleaning is carried out by bottom injection of oxygen, sulfur dioxide, and pulverized coal. The studies undertaken as part of this research involved cold mode/experiments in a QS-type reactor. Cold model studies were carried out in a shallow channel reactor with high-strength bottom gas injection in a liquid bat
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