Optimization of pyroprocessing of zinc sulfide ore to produce ferroalloy and zinc

Abstract

The article presents the results of thermodynamic analysis and experiments on the electric smelting of Shalkiya ore (5.2% of ZnS, 1.0% of PbS, 50% of SiO2) with the joint producing a silicon-containing ferroalloy and extracting zinc and lead into sublimates. The studies included the thermodynamic modeling using the HSC-6.0 software package and electric smelting in an arc furnace. It was established that the interaction in a ZnS-Fe3O4-2C system under equilibrium conditions is of a stepwise nature with the initial reduction of Fe3O4 to Fe and FeO at 600-1000 °C, then the interaction of ZnS with Fe at 1100-1800 °C with the formation of gaseous zinc, and the interaction of ZnS with FeO with the predominant formation of zinc at temperatures above 1600 °C. The electric smelting a charge containing the Shalkiya ore, coke, magnetite concentrate (85.9% of Fe3O4) and steel shavings allowed us to establish that FeSi45 grade ferrosilicon (41.8-44.6% of Si), with the extraction of 80-85.4% of Si, can be produced in the presence of 24.9-30% of coke with the replacement of magnetite’s iron by steel shavings’ iron from 20.9 to 91.8%. A lower degree of this replacement is associated with intensive development of foaming and a decrease in the extraction of silicon into the alloy. At least 98% of zinc and 96% of lead are extracted into the resulting sublimates containing 29.4% of zinc and 15.1% of lead.