Experimental investigation and three-dimensional computational fluid-dynamics modeling of the flash-converting furnace s
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I. INTRODUCTION
THE Kennecott–Outokumpu flash-converting process is a new technology to produce blister copper. This process incorporates the principles of the Outokumpu flash-smelting process in the converting step of coppermaking. The flashconverting process is aimed at replacing the converting of molten copper matte in Peirce–Smith converters. In the flash-converting process (Figure 1), fine copper matte particles and flux particles are fed into a furnace shaft, where a high-strength oxygen-enriched gas stream is injected. In the reaction shaft, the particles are quickly dispersed, heated by the reactor walls and the gas until ignition, partly oxidized, and melted. The molten particles settle in the furnace bottom, where incompletely oxidized sulfides react with metal oxides to produce blister copper, and the blister copper and slag phases are separated. Some of the key benefits of the flash-converting process MANUEL PEREZ-TELLO, formerly Graduate Student, Department of Chemical and Fuels Engineering, University of Utah, is Associate Professor, Department of Chemical Engineering and Metallurgy, University of Sonora, Sonora, Mexico 83000. HONG YONG SOHN, Professor, is with the Department of Metallurgical Engineering, University of Utah, Salt Lake City, UT 84112. KIRSI ST. MARIE, formerly Research Associate, Department of Metallurgical Engineering, University of Utah, Engineer, is with Reaction Engineering International, Salt Lake City, UT 84101. ARI JOKILAAKSO, Docent, is with the Department of Materials Science and Rock Engineering, Helsinki University of Technology, FIN-02150 Espoo, Finland. Manuscript submitted May 26, 2000. METALLURGICAL AND MATERIALS TRANSACTIONS B
include[1–5] continuous operation, little emission of gaseous pollutants, and avoidance of the handling of molten matte. The first industrial-scale application of the flash-converting process was started at the Utah copper smelter in 1995.[2,3] These features make this the cleanest copper converting process currently in operation. Emissions are highly controlled, with sulfur capture in excess of 99.9 pct, equivalent to 3 kg of SO2 per tonne of copper, the lowest emission in the world.[5] Although the flash-converting process has been under development since the early 1980s, experimental data on its performance have been rather scarce until recently. Asteljoki et al.[1] and Asteljoki and Kyto¨[4] reported on experimental data from a flash-converting pilot-scale facility. They analyzed the copper losses in the slag phase and the distribution of minor elements between the blister copper and slag in the settler. Whereas the residence time of the particles in the shaft is of the order of seconds, the residence time of the melt and slag in the settler is of the order of hours. Therefore, the information concerning the behavior of gas and particles in the reaction shaft was not available from these tests. Suominen et al.[6,7] reported on oxidation tests of industrial copper matte particles in a laminar-flow reactor. Test variables included the particle
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