Sponsored by: SMD Non-Ferrous Metals Committe, EPD Pyrometallurgy and Process Fundamentals
Program Organizers: Debabrata Saha, Metals Industries Group, Air Products and Chemicals, Inc., Allentown, PA 18195; William E. Frazier, Naval Warfare Center, Warminster, PA 18974; William P. Imrie, Bechtel Group, San Francisco, CA 94105; Prof. David G. Robertson, Department of Metallurgical Engineering, University of Missouri, Rolla, MO 65401
Tuesday, PM Room: B8
February 6, 1996 Location: Anaheim Convention Center
Session Chairpersons: William E. Frazier, Naval Warfare Center, Warminster, PA 18974; William P. Imrie, Bechtel Group, Inc., San Francisco, CA 94105
SOME GENERAL CHARACTERISTICS OF CONTINUOUS GAS-STIRRED REACTORS: L.Li, G. Trapaga, J. Szekely, Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
Abstract not available.
KINETIC STUDY OF As, Sb, AND Bi REMOVAL FROM COPPER BY SF6 INJECTION: B. Zhao, N.J. Themelis, Columbia University, Dept. of Chemical Engineering, Materials and Mining Engineering, New York, NY 10027
Laboratory experiments have been conducted on the removal of As, Sb and Bi from molten copper by SF6 injection. The results showed that the impurities can be removed by SF6 injection in the sequence of Sb>As>Bi and the rate of Bi removal is affected significantly by the concentration levels of As and Sb in the copper melt. Analysis of the experimental data indicates that the impurity removal process is under chemical reaction control rather than by mass transfer of impurity through the molten copper phase. On the basis of experimental results, a kinetic model was developed and the order of chemical reaction and the volumetric chemical reaction rate coefficients of impurity removal were determined.
A STUDY OF THERMODYNAMICS AND KINETICS OF NITROGEN ABSORPTION AND ITS REMOVAL FROM LIQUID NI-CR ALLOYS USING THE SIVERTS' TECHNIQUE: L. Petitnicolas, A. Jardy, D. Ablitzer, Ecole des Mines, Parc de Saurupt, 54042 Nancy Cedex, France
The experimental study of nitrogen absorption and its removal from a liquid Ni-20% Cr alloy has been undertaken. We use an experimental apparatus based on the Sieverts' technique in order to determine the solubility of nitrogen in the alloy, as well as the kinetics of nitrogen transfer across the gas/melt interface. Experiments show that nitrogen solute equilibrium content can be calculated using the classical Sieverts' rule. The nitrogen absorption/removal behaves as an overall reaction involving convective/diffusive transport of nitrogen solute within the bulk liquid phase, as well as the chemical reaction at the gas/liquid interface, which is based on an adsorption-desorption mechanism. Measurements show the nitrogen reaction rate to be well described by first order kinetics, whereas experiments on nitrogen removal reveal that the rate is better expressed using a second order equation.
NITROGEN GAS REACTIONS WITH MOLTEN ALUMINUM AND ALUMINUM ALLOYS: J.F. Flumerfelt, I.E. Anderson, Ames Laboratory, Iowa State University, Ames, IA 50011-3200
Molten Al and Al alloys containing Si, Mn, Ti, and Y have been lanced with nitrogen-bearing gases. These lancing experiments provided the means for observing what phases form during exposure to nitrogen-bearing gases for finite periods of time, <2 minutes, at high temperatures, >1200deg.C. The experiments were conducted in an induction heated drop tube furnace apparatus. The overall premise of these experiments was to select those Al alloys and gas compositions that show promise of forming secondary dispersoid phases, particularly AIN, in the Al matrix. The alloys selected will be atomized using gas atomization reaction synthesis (GARS) using the most favorable conditions. In this case, the chosen Al alloy will be atomized with a nitrogen-bearing gas, such that the Al and gaseous nitrogen species react to form a dispersoid phase within each powder particle. The powder particles that result from this "aggressive" GARS process would be essentially Al metal-matrix composites within a uniform distribution of dispersoids. To date, only high-purity Al has been atomized using a mild GARS reaction. This work is funded by the Materials Science Division of DOE-BES under contract number W-7405-Eng-82.
3:20 pm BREAK
PHYSICAL MODEL STUDY ON SPLASHING BY TOP BLOWING GAS INJECTION ONTO LIQUID BATH: S. Okabe, H. Sato, F. Tanaka, E. Kimure, Mitsubishi Materials Corporation, Pyrometallurgical Process Laboratory, Omiya, Saitama, Japan
Top blowing lance technique is employed by the Mitsubishi Continuous Copper Converter for the continuous supply of reaction gases onto molten bath. In order to minimize the refractory wear caused by the interaction between the furnace lining and the melt splash, optimum furnace design and blowing condition are required. An empirical equation obtained by the physical model study enables the estimation of the splattering rate on a vertical plane at a certain distance from the lance. The effect of the ceiling position was considered as well. The application of the equation to the furnace design of the Mitsubishi Converter is discussed.
INTERACTIONS OF LARGE GAS BUBBLES WITH FLUID INTERFACES: L.Jong-Leng, A. Guerra, N. Gray, Department of Chemical Engineering, University of Melbourne, Parkville, Victoria, Australia 3052
A survey of the interactions of large gas bubbles formed from top and bottom injection of gases into melts was carried out. Spherical cap bubbles were found not to produce much splash when they break through the bath free surface except for that formed by plunging of the spout its edges. In contrast, the bursting of balloons produces cavities which give rise to liquid jets being ejected from the bath free surface. The position of the balloons relative to the bath free surface is an important parameter in the formation of the liquid jet. This is compared with bubbles formed from top and bottom gas injection to give plausible mechanism for the formation of splash in intensive bath smelting processes. It is found that the interaction of the free surface movement with the gas plume is important in predicting the splash behavior of gas injected systems.
THE CHLORINE-ALUMINUM INTERFACE: G. Saevarsdottir, T. Gudmundsson, T.I. Sigfusson, University of Iceland, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland
For decades the aluminum industry has been practicing gas treatment of aluminum melts. This treatment is of great importance because of its influence on gas and inclusion removal from the melt. The gas - melt interaction is greatly influenced by the gas composition and melt temperature. This paper gives an overview of the interaction between argon/chlorine gas mixtures and the aluminum melt. It covers the thermodynamics of the reaction between the chlorine and number of different elements commonly found in liquid aluminum. The paper reports an experimental study of the behavior of the chlorine - aluminum interface which is the key to understanding the role of chlorine in the liquid metal.
INTERACTIONS BETWEEN MELT AND CHLORINE IN CHLORINE FLUXING OF ALUMINUM: Q. Fu, J.W. Evans, Department of Materials Science and Mineral Engineering, University of California, Berkley, CA 94720-1760
Although chlorine fluxing to remove magnesium has been widely practiced in the aluminum industry for many years, there appear to have been few fundamental studies of the kinetics and transport phenomena involved. The paper describes such a study in which the rates of reaction of individual argon/chlorine bubbles with aluminum/magnesium melts were measured. The detachment of bubbles from a submerged nozzle, at variable depth in the melt, was detected by a microphone and the arrival of the bubble at the top surface by conductivity probes. Analysis of exit gases and mass balances yielded the overall progress of reaction. Experimental results are interpreted in terms of heterogeneous reaction kinetics and mass transport to the bubble-melt interface.
IMPACT OF GASES ON METAL PROCESSING AT INDAL: C. Ramasamy, Indian Aluminum Company, Ltd., Taloja, Dt. Raigad, Maharashtra 410208, India
The winds of liberalization blowing across India have sent the tariff barriers, that have provided protection to industry, crashing. Where as, imports are perceived to be a major threat, it is also seen as an opportunity to penetrate global market with quality upgrades. India will also have to tighten environmental regulations in line with G7 countries over time. Our company mission on new equipment selection calls for design that is World Class in terms of quality, cost effectiveness and environment. In the above context, use of appropriate gases for processing aluminum assumes great importance. For example, aluminum processing involves chlorine - nitrogen during holding furnace operation, argon during treatment of dross and nitrogen/generator gas for annealing of metal. The paper discusses the current and proposed quality standards in India and the implication of this on the uses of gases on one hand and the increasing stringency of ecological regulation on the other. Essentially, therefore, it boils down to the question of balancing cost, quality and environment and the need, perhaps, to develop technology that addresses the needs.
OXY-FUEL COPPER MELTING FOR INCREASED PRODUCTIVITY AND PROCESS ENHANCEMENT: C.T. Ebeling, AGA Gas, Inc., Cleveland, OH 44131
The purpose of this paper is to discuss the implementation and results derived
from installing oxy-fuel burners in a 180-ton copper reverbatory melting
furnace. This installation has been in operation since the fall of 1993.
Specific results will be discussed in the areas of melt chemistry, furnace
modifications, productivity, process enhancements and the combustion system
capabilities. Similarly, the methodology of the installation and progress of
more recent modifications will be addressed.
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