| The purpose of this investigation was to elucidate the transport phenomena and get a better understanding of the nature of the physical and chemical transformations that occur in the shaft of a flash smelter. (a) The first part involved a thorough review of the literature on Outokumpu flash smelting furnaces around the world and comparison of the principal operating parameters in the reaction shaft of the smelting furnace. (b) The second part involved an experimental investigation of the degree of reaction and mineral transformation of copper concentrates under simulated flash smelting conditions. An electrically heated 0.13m by 2m high laboratory flash reactor was designed and constructed, so that the gas-particle stream in the reactor shaft represents a cylindrical core of dispersed particles in an industrial smelter. Process conditions similar to those found in an industrial smelter were used, with the objective of investigating the effect of variations in the principal operating parameters on the degree of reaction of copper concentrate.; The axial temperature profiles in the gas flow through the reactor and the rate of heat transfer by convection between gas and reactor wall were first determined. Flash reaction tests were then conducted on the effects of particle size, concentrate feed rate, oxygen loading ratio, oxygen-enrichment and reactor wall temperature (973-1273K) on the degree of reaction of copper concentrate.; In general, the results obtained in this study have shown that the degree of oxidation increases with oxygen loading, oxygen-enrichment, particle residence time and with a decrease in particle size.; Particle fragmentation during smelting was investigated by comparing the particle size distribution of the concentrate particles before and after each experimental run. Fragmentation was found to occur with particles over 70 microns in diameter and to increase with oxygen enrichment.; Mineralogical analysis of flash smelting products collected at three levels in the experimental reactor showed: Intermediate solid solution, bornite, chalcocite, metallic copper, magnetite, iron-copper spinel, pyrrhotite, hematite, delafossite and cuprite phases. Close examination of these quenched phases has led to the postulation of a sequence of mineralogical transformations of chalcopyrite during oxidation in the reaction shaft. (Abstract shortened with permission of author.)... |
