| An experimental and mathematical investigation has been carried out to study the chemical changes occurring in chalcopyrite concentrate particles when oxidized in a flash furnace. The study was primarily aimed at developing mathematical expressions to describe the chemical changes in the chalcopyrite particles which can then be combined with models for turbulent fluid flow and heat and mass transport in order to describe the overall flash-smelting process. Additionally, experimental work was carried out to collect data from a laboratory-scale flash furnace which can be used to test the comprehensive model.; Isothermal and nonisothermal studies have been carried out on the intrinsic rate of sulfur removal from chalcopyrite particles by oxidation. In the initial stage of reaction, below about 873 K, the direct oxidation of chalcopyrite particles is the dominant sulfur-removal step, whereas above this temperature sulfur vaporization predominates. The oxidation of chalcopyrite particles under flash smelting conditions has been analyzed by combining the kinetics of single-particle oxidation with equations describing heat and mass transfer between the particle and its surroundings. The effects of various parameters such as oxygen concentration, particle size, gas and wall temperatures, and reaction time have been elucidated. The above model has been further modified by making appropriate assumptions to describe the combustion and ignition of chalcopyrite under flash-smelting conditions.; By considering the volatilization of minor elements from the molten particle and the distribution of these elements between the molten phases in the settler, a mathematical model has been developed to describe the behavior of minor elements during flash smelting of copper concentrate. Excellent agreement has been obtained between the observed and predicted behaviors. The influence of oxygen enrichment, matte grade, and wall temperature, as well as the bath temperature, on minor-element behavior has been elucidated.; Finally, a laboratory-scale flash-smelting reactor has been built and tested. Copper concentrates have been flash-smelted in the reactor. Samples of gas and partially reacted particles have been collected at various positions within the reactor. The measured variables are the bulk-gas temperature and composition and sulfur content of the particles. The effects of solids-loading ratio in the inlet stream and oxygen concentration of the bulk gas on the above-mentioned variables have been determined. |
