Beneficiation of High Ash Non-Coking Coal from Vasundhra Mines, Odisha

Abstract

Coal is the vital energy fuel world-over, statistically contributing to 55% of installed energy generation capacity during the calendar year 2011 and it plays a pivotal role in the macro- economic development of the country. India has definitive coal reserves estimated by the Ministry of Coal at 93 billion tonnes, which is estimated to suffice and cater to energy generation requirement of the country, spanning over 30 to 60 years with proper scientific exploitation. However, Indian coal has been observed to be of low quality on account of its high ash content attribute and the high ash non-coking category coal constitutes sizeable quantity of near-gravity materials (NGM), which entails beneficiation to suit end-user or application specific qualitative level. The present manuscript demonstrates the beneficiation of high ash non-coking coal from Vasundhara mines, with 57% ash content intended for scaling down the ash content to 25% in obtaining clean coal at a reasonable yield, deploying physical beneficiation techniques. The coal was characterised thoroughly in terms of petrographic characteristics, size analysis, washability and chemical composition and the gross calorific value of the coal was observed to be 3221 Kcal/kg. The processing was initiated at a top size of 6.3 mm after initial deshaling of the ROM coal on account of its high ash content. Tactical combination of gravity separation and flotation techniques yielded clean coal with 25% ash at 40% yield and an intermediate clean product with 49% ash at 12% yield. The low ash content in the final clean coal is possibly achievable from the combined clean coal with 25% ash content adopting chemical beneficiation route.