A Total Package in Utilisation of Low Rank Coals and Related Fossil Fuels

Occurrence of petroleum and natural gas in intimate association with coal in various coalfields has led to the development of the concept that a large part of hydrocarbons are generated from coal and plant derived sources, especially from the exinite group of coal macerals. In certain part of North East India, it was observed that coals record, exceptiona1ly high volatile matter and hydrogen content. These coals have been found to yield very high amount of tar. The associated carbonaceous shales, shaly coal and durainous layers of these areas may contain appreciable amount of exinites and may virtually grade into hydrocarbon source rock.

In the Gondwana basins inferior layers like shaly coal, durainous coals and carbonaceous shales are integral part of the coal seams which may sometimes contain considerable quantum of exinite - the principal hydrocarbon generating coal macera1. In case of beneficiation of the low rank coals, these materials are likely to be incorporated in the high ash fractions as rejects. The authors consider that to derive full benefit, high ash low rank coals should be subjected to low temperature carbonisation. The tar or hydrocarbon crude thus obtained from different sources could be brought to a central pool for further treatment for conversion to petroleum substitute fuels and chemicals. Ammonical liquor and gas are additional by-products of the process whereas the soft coke or char can be beneficiated and utilised for power generation and various other purposes. The high ash content of the coals would give rise to serious ecological threat and problems of waste disposal which can be profitably surmounted by converting fly ash to construction materials like bricks and road metal.