Improving Blast-Furnace Smelting Indices Through More Efficient Screening of Sinter Fines

Abstract

Reducing the amount of fines in a blast-furnace charge significantly increases furnace productivity while also decreasing coke rate and the cost of making pig iron. The agglomeration facility at the metallurgical combine of EZRAZ ZSMK was originally designed to make one type of concentrate for blast-furnace smelting. The capacity of the warehouses where raw materials are averaged and the capacities of the equipment for crushing, screening, and delivering limestone to the facility were planned accordingly. The charge which is currently used for the sintering machines contains up to 10 iron-bearing components (concentrates, ores, additives) that differ significantly from one another in their chemical composition and physicochemical properties (granulometric composition, initial and final melting points, etc.). Irregular deliveries of iron-ore-based raw materials, the small reserves of these materials, and the inadequate storage capacity of the warehouses are adversely affecting the conditions under which the materials are averaged, thus leading to a reduction in the sinter’s mechanical strength and an increase in its content of fines. Implementation of a plan to improve the designs of the screens and screening surfaces and introduce measures to reduce the sinter’s content of fines has made it possible to lower the amount of fines in skip coke by 0.4–0.6 abs.%, improve the gasdynamic regime of the blast furnaces, increase productivity by 0.1–0.3%, and reduce the coke rate by 0.1–0.2%.