Evaluating the Efficiency of Blast Furnaces and the Prospects of Blast-Furnace Smelting

The productivity of a blast furnace is determined by the gas permeability of the stock and the amount of gas formed for each ton of pig iron that is made, i.e., it is determined by the amount of fuel consumed and the oxygen content of the blast. The indices used to characterize the unit productivity of blast furnaces and the smelting rate inside them per square meter of their volume formally depend on the height of the furnace. It is incorrect to use these indices to compare the performance of furnaces which are of different volumes. Use of the indices by the authors of [3] to compare smelting rates on blast furnaces in the 1940–1950s and modern furnaces led them to conclude that smelting rate is not increased by increasing the furnace’s topgas pressure and enriching the air blast with oxygen. In order to objectively compare the efficiency of blast furnaces that differ in volume, it is necessary to use unit-productivity and smelting-rate indices that are calculated for each square meter of the cross section of the hearth. The methods currently used to operate blast furnaces at the Nizhniy Tagil Metallurgical Combine and Novolipetsk Metallurgical Combine show that as long as the coke and iron-ore-bearing charge materials which are used are of acceptable quality, raising the top-gas pressure and the increasing the oxygen content of the blast make it possible to achieve record values for blast furnaces’ productivity and smelting-rate indices.