Beneficiation Studies of Low Volatile Coking Coals of India for Metallurgical Uses

摘要

The relative abundance of coal in India compared to other fossil fuels makes it a natural choice as the primary source of fuel, be it for steel making, power generation or for other uses. As on today, the total reserves of coal in India is 299 billion tonnes. Out of which about 83% constitute non-coking coal, 14% coking coal and the rest are others. Coking coal is an essential input for production of Iron & Steel through blast furnace route. To save steel industry facing acute dependence on imported coking coal, domestic availability of coking coal in desired quality has become imperative. The good quality coking coals of the upper seams are fast depleting leaving behind the inferior quality lower seam coal. Coking coal requirements for the Indian steel industry are estimated to be around 40 to 50Mt for the year 2014-15. The indigenous supply of coking coal is about 10 to 15 Mt; the rest is being imported from countries like Australia, USA, China etc., thereby putting considerable pressure on the foreign exchange reserve of the country. Low volatile coking coal (LVCC), though inferior in qualities but abundantly available in Eastern part of the country may be an immediate choice. These coals, being of lower seams are likely to be more matured (Ro ～1.30%) than the upper seams and consequently exhibit lower values of volatile matter. The country has a moderate reserve of such coal, amounting to about 50% of the total coking coal reserve. Unfortunately, the washability potential of this coal is so poor that the existing washeries having conventional washing technologies may not able to supply coals of ash 17-18% as desired by indigenous metallurgical industries and cannot stand in competition with foreign coals because of poor yield of clean coal. As such, these coals are being treated as NLW (Non-linked washery grade) and are supplied to the thermal power plants, against augmenting the demand of metallurgical coal for coke making thus, wasting the scarce coking coal resources. The present paper highlights some of the beneficiation studies followed by characterization studies for augmentation of coking coal resources for metallurgical purposes.