High Ash Non-Coking Coal from India: Beneficiation and Implications

Abstract

In the entire spectrum of industrialization from global perspective, coal as the primary source of energy is the fulcrum of major developmental factors on which hinges the growth of economy at macro level, supposedly vital for improvement in quality of living conditions, thereby, impacting the lives of millions across the world. The International Energy Agency (IEA) as well as national/regional energy agencies have projected coal to be the key component of energy mix well into the future. The primacy of coal as source of energy is factually expected to surpass the significance of oil as a typical and primary source of energy in next 4-5 years, and this phenomena per se has the potential in accomplishing the much desired cost economy in providing respite from consistent escalation in input cost of energy generation. India by definitive coal reserves estimation undertaken by the Ministry of Coal is pegged at 93 billion tonnes, and with appropriate investigation and advancement in efficacious methodologies for scientific exploitation, the estimated reserve is sufficient to cater to energy generation requirement of the country, spanning over 30 to 60 years. 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, Odhisa, 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, chemical composition and the gross calorific value of the coal was observed to be 3221 Kcal/kg. The beneficiation process was initiated at a top size of 6.3 mm after initial deshaling of the ROM coal. 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. Low ash content in the final clean coal is possibly achievable from the combined clean coal with 25% ash content adopting chemical beneficiation route.