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

¹ Higher School of Chemical Engineering and Biotechnology, Mukhtar Auezov South Kazakhstan University, Department of Technologies of silicate materials and metallurgy, Tauke Khan avenue 5, 160012 Shymkent, Kazakhstan
² National Center on Complex Processing of Mineral Raw Materials of the Republic of Kazakhstan, Jandossov str. 67, 050036 Almaty, Kazakhstan
³ Saint-Petersburg State Institute of Technology, Department of General Chemical Technology and Catalysis, Moskovsky avenue, 26, 190013, Saint-Petersburg, Russia

^* Corresponding author: shevkovm@mail.ru

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.