Beneficiation of non-coking coals: basic concepts and technology routes

Abstract

Coal is the most important primary source of commercial energy in India. The importance of coal is bound to increase for the coming years with the growth of coal consuming industries. Power sector is the most potential consumer of the non-coking coal, consuming more than 70% of the total coal production of the country. With increasing consumption, coal will continue to enjoy a prime position in the overall energy scene in India. Many coal consuming plants including the power plants obtain coal from more than one source and the coal is of varying quality and size. Due to the fluctuations in the grain size distribution, top size, ash and moisture content in the coal fed to the thermal power plants, it is not possible to ensure adequate homogenization of coal quality in the absence of proper and adequate blending facilities at the power plant end. In view of the above situation, beneficiation of power coal appears to be the only solution to reduce ash of the coal and the quantity of coal to be transported, mainly by rail thus reducing demand for railway rakes and resulting in overall savings in expenditure of freight. The purpose of beneficiation of non-coking coal is not only to reduce its inert content for transportation or to minimize abrasive materials but mainly to improve its combustion qualities. The combustion properties of coal like heating value, volatile matter content, char characteristics, abrasivity, etc. Since clean and efficient combustion is on demand today, optimization of such quality parameters for the purpose of beneficiation is felt necessary to impart desired qualities to the beneficiated coal. The geological reserves of non-coking coal, its grades with characterization, consumption of the coal by various industries, characteristics of coal for various end users like power, sponge iron and cement industries has been discussed. The concept of preparing Indian non-coking coals conceived by Erstwhile Central Fuel Research Institute, particularly for non-coking coal has been discussed. The technology routes for the upgradation of the non-coking coals by different processes has also been discussed in brief. The address ends with a comparative statement of using various washing systems in terms of feed size, Ecart probable values, cost of investment, power consumption, etc. and concluding remarks.