How the steel industry can get the best out of Indian coal

Abstract

Coal, particularly coking coal is a vital raw material for the steel industry, since coke plays a key role in blast furnace ironmaking. Efforts are always made to reduce the consumption of coke in blast furnaces by injection of non-coking coal through the tuyeres. This automatically imposes severe restrictions on the quality of blast furnace coke. Furthermore, for coal injection to be effective, the injected coal has to be carefully selected so that it does not drastically alter the conditions prevailing in the blast furnace raceway. The quality of blast furnace coke depends on: the properties of the coal blend used, the process used for cokemaking including the technique of pre-carbonisation employed (if any), and to a lesser extent, on post-carbonisation operations. The influence of the properties of coking coal on blast furnace coke and the parameters involved in the choice of non-coking coal for coal injection are discussed in this paper. In India, there is dearth of both coking as well as non-coking coal suitable for the steel industry. Intensive efforts in terms of coal selection, up-gradation by beneficiation, etc. are required to optimise the properties (particularly the ash content) of Indian coal. In addition, in order to produce high grade coke from weakly coking Indian coking coals, blending with low ash imported coal of high rank is essential. The cost incurred on imported coal can be controlled by paying simultaneous attention to the preparation of indigenous coals.