Removal of antimony from copper by injection of soda ash
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1.25Qg0"29 -t- 0.28
(H Qf)
where Qg is the injection gas flow rate in normal liters per minute, H is the depth of injection in centimeters, and Qy the rate of flux injection in grams per second. I.
INTRODUCTION
IN recent
years, the need for more stringent environmental control has caused copper producers to seek ways for reducing appreciably the emission of sulfur dioxide and particulate matter into the atmosphere. This has resuited in the adoption of processes which have the ability to simultaneously smelt and convert copper concentrates to a high-grade matte or, eventually, to crude metal. Three of these novel processes have already been installed in the United States: the Outokumpu flash smelters at Hidalgo, NM, and at San Manuel, AZ, [11 the Noranda Process in Salt Lake City, UT, t2~ and the INCO* *INCO is a trademark of Inco Alloys International, Inc., Huntington, WV.
flash smelters t31 at Hayden, AZ and at Silver City, NM. In all cases, their installation has resulted in improving the environmental quality of the area and in reducing energy consumption per ton of copper produced. However, it has not yet been possible to exploit the capability of such processes to directly smelt concentrates to metallic copper in a single furnace. Therefore, it is still ncessary to transfer molten matte from the smelting furnace to conventional batch Peirce-Smith converters where the remaining sulfur is driven off by means of oxidation by air injected through tuyeres. This batch converting step produces a large volume of sulfurcontaining gases and is the source of severe fugitive emissions of sulfur oxides and fume. The principal obstacle to the single-stage smelting of concentrates to copper in a single vessel is that, when copper is produced in the smelting furnace, impurities
TADEUSZ T. STAPUREWICZ, Visiting Professor, is with the Department of Metallurgical Engineering, University of Missouri-Rolla, Rolla, MO 65401. NICKOLAS J. THEMELIS, Professor of Mineral Engineering, is with the Henry Krumb School of Mines, Columbia University, New York, NY 10027. Manuscript submitted March 26, 1990. METALLURGICAL TRANSACTIONS B
such as Sb, As, and Bi report preferentially to the copper phase and prevent its use in the subsequent electrorefining step. For instance, in the case of antimony, its concentration in the direct-smelted copper can be as high as 0.5 pet (5000 ppm), depending on the antimony content of the concentrates; however, the electrorefinery has difficulty processing anode copper that contains more than 300 ppm of antimony. One way of overcoming this obstacle is to subject the impure molten copper to reaction with appropriate gases and solids which will react with the impurities and remove them in the form of a slag. Such a pyrorefining step m a y be incorporated in the conventional oxidationdeoxidation stage in which the blister copper is refined to copper anodes. There have been a few papers on the use of fluxes, such as sodium and calcium carbonate, t5,61 for removing impurities. However, none of these processe
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