Injection of iron-bearing concentrates derived from steel-smelting slag into the converter bath

Abstract

Steel-smelting slags form a large proportion of metallurgical wastes. They are generated at a rate of 150–200 kg/t of steel, on average. At current rates of steel production in Russia, the annual output of smelting slag is 9 million t, of which 8–11% consists of metallic iron and 15–40% of iron oxides. The total iron content in the slag is 20–30 wt %. Steel-smelting slag represents a valuable source of iron, which should be processed and returned to production. The slag-processing system at AO EVRAZ ZSMK permits stepwise removal of iron-bearing inclusions from the slag by magnetic separation. The iron-bearing concentrate obtained consists of three fractions: 0–10 mm (for use in sinter production); 10–80 mm (for blast-furnace use); and 80–250 mm (for use in steel smelting). The use of the 0–10 and 10–80 mm fractions in steel production in 160-t converters is considered in the present work. A mathematical model permits multivariant calculations to investigate the smelting dynamics and the distribution of added iron-bearing concentrates in the metallic melt, for different trajectories and dosing protocols. Analysis of the results yields new information regarding the hydrodynamic processes when iron-bearing concentrates from the slag-processing system at AO EVRAZ ZSMK are injected in the converter bath.