Use of recycled materials in pig-iron production at a non-integrated metallurgical plant

Slags of the required basicity are obtained in blast furnaces at the Lipetsk Metallurgical Plant by adding raw fluxes (limestone and dolomite) to the charge in amounts of 200-300 kg/ton pig iron. Decomposition of the carbonates of calcium and magnesium in these fluxes requires a considerable amount of heat and increases coke consumption in the smelting operation by 45-65 kg/ton pig. To replace the limestone in the charge, the plant uses crushed rock obtained from converter slag. The rock is delivered by the Novolipetsk Metallurgical Combine and is of the 40-70 mm fraction. Most of the economic benefit from using converter slag stems from the replacement of a raw flux (limestone) by lime present in the slag in free form and in the form of compounds-mainly calcium silicates. An equally important factor that affects the cost-effectiveness of using converter slag in the blast-furnace charge is the slag's 20% iron content. A substantial percentage of the iron in the slag is in the form of FeO and metallic inclusions.