Kinetics of deoxidation of liquid copper by graphite particles during submerged injection
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A. Injection Refining H I G H speed submerged gas-particle jets are an important part of many modem high productivity liquid metal refining processes, because they are simple, inexpensive, and can achieve very high rates of refining. In such processes, a jet of gas is used to entrain powdered reagents and to carry them into a liquid metal bath where the refining operation is performed. In addition to providing the advantages of pneumatic transport of reagents for economy and ease of control, the rate of the refining process is accelerated because of (1) the high surface-tovolume ratio of the injected particles; (2) the vigorous stirring produced by the high-speed gas jet; and (3) the steep concentration gradients around the particles which maximize the rate of mass transfer. {]] Injection refining of liquid metal in ladles after primary refining is of growing importance in the steel industry and has many potential applications in the refining of other metals. [2,3.4] To minimize costs, the operating parameters of a ladle injection refining system should be adjusted so as to maximize the recovery of the reagent and minimize the time of the treatment and the attack of refractories during the treatment. Optimization of the operation of an injection refining operation is complicated by the number of variables which could conceivably affect the efficiency of the process. These parameters include the diameter, location, and orientation of the lance within the ladle, the velocity and particle loading of the jet, and the size, size distribution, and shape of the injected particles. The optimum conditions for injection refining may vary from Y.W. CHANG, formerly Graduate Student with the Department of Civil Engineering, Mechanics, and Metallurgy, University of Illinois at Chicago, is Research Associate, Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801. M.J. McNALLAN, Associate Professor of Metallurgy, is with the Department of Civil Engineering, Mechanics, and Metallurgy, University of Illinois at Chicago, P.O. Box 4348, Chicago, IL 60680. This paper is based on a presentation made in the T.B. King Memorial Symposium on "Physical Chemistry in Metals Processing" presented at the Annual Meeting of The Metallurgical Society, Denver, CO, February, 1987, under the auspices of the Physical Chemistry Committee and the PTD/ISS. METALLURGICAL TRANSACTIONS B
one system to another because of differences in fluid properties such as density, viscosity, and surface tension, reagent properties such as density and reactivity, and system properties such as ladle dimensions. The task of identifying the optimum conditions for injection refining would be much easier if a general model for reaction kinetics in such systems was available. Very few laboratory studies have been performed which can provide useful information for the development and testing of such a model. The majority of the laboratory injection studies have made use of water models or other low temperature analogs to l
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