THERMODYNAMIC SIMULATION-MODEL OF THE ISASMELT PROCESS FOR COPPER MATTE

A computer model has been constructed to simulate thermodynamically th e behavior of the minor elements Zn, Pb, As, Sb, and Bi as well as the major elements Cu, Fe, Si, O, and S in the Isasmelt process, producin g copper matte. The model is based on the new concept that there are t wo independent reaction sites in a slag bath: one for fast oxidation a nd the other for slow reduction. The oxidizing reaction at the first s ite produces matte, magnetite-rich slag and gas from chalcopyritic con centrate and siliceous flux. The slag is then partially reduced with l ump coal at a site removed-from the first site. The oxidizing and redu cing reactions are assumed to proceed under a separate set of equilibr ium conditions. The process heat balance and thermodynamic distributio n of the minor elements are united and expressed as functions of varyi ng weights and compositions of concentrate, flux (silica, limestone), coal, oil, and oxygen-enriched air. The process chemistry was analyzed in terms of Fe3O4, FeO, and FeS activities, as well as SO2 partial pr essure. The thermodynamic model explains well the minor element distri butions observed in the 15 tons per hour pilot furnace, and it is used to project the optimal smelting conditions; for the full-scale 100 to ns per hour Isasmelt furnace.