Experimental and theoretical study of particle dispersion phenomena in a turbulent gas jet of the flash-smelting process
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I.
INTRODUCTION
F L A S H smelting is a pyrometallurgical process for smelting metal sulfide concentrates. In flash smelting, fine particles of sulfide concentrate are injected with the process gas through the concentrate burner, forming a turbulent particle-laden jet. Since the concentrate particles undergo oxidation reaction in flight, particle dispersion is a major factor in controlling the degree of oxidation of each concentrate particle. The configuration of the concentrate burner and the flow rate of the process gas significantly affect the particle dispersion in the jet. For improved burner design, it is necessary to understand how the particles disperse in the jet and how the dispersion phenomena are affected by the flow conditions and geometry of the burner. Experimental work on a simplified system can provide important information for the basic understanding of the particle dispersion phenomena. On the other hand, development should be based on theoretical background. Hahn and Sohn ~1,31 and Hahn 12] developed a mathematical model to describe the various processes taking place in a flash furnace. The mathematical model provides a fundamental basis for the design and optimization of the concentrate burner. The model was verified by comparing the predicted results with measurements in a laboratory flash furnace and a pilot plant furnace. A detailed description of the particle behavior, which has a significant effect on the predicted results of the mathematical model, however, was not developed. The predictive ability of the mathematical model should be verified in terms of the particle behavior in a turbulent gas jet. It was the purpose of this research to carry out an experimental and mathematical simulation investigation to determine the effects of various operating parameters on the particle dispersion in such a turbulent gas jet. YUTAKA YASUDA, formerly Graduate Student, Department of Metallurgical Engineering, University of Utah, is Process Engineer, Saganoseki Smelter & Refinery, Nippon Mining and Metals Co., Ltd., Saganoseki, Oita, Japan. H.Y. SOHN, Professor, is with the Department of Metallurgical Engineering, University of Utah, Salt Lake City, UT 84112-1183. Manuscript submitted May 5, 1994. METALLURGICALAND MATERIALS TRANSACTIONS B
II.
EXPERIMENTAL
To investigate the particle dispersion phenomena in a jet, the particle number density was measured under isothermal and nonreacting conditions. The experimental particle number density data were compared with the predicted results of the mathematical model.
A. Experimental Facility The experimental apparatus is shown schematically in Figure 1. Pressurized air (500 to 800 kPa) was supplied by a compressor. A pressure regulator with an air filter was used to set the air flow rate, which was measured with a rotameter. A particle feeder was installed above the observation chamber. To minimize the pulsing of the particle feed, a tandem arrangement of an Acrison screw feeder and a Syntron vibratory feeder was used. The particles used in this work wer
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