FUEL/POWER MINERALS: COAL

FUEL/POWER MINERALS

1. COAL A principal mineral fuel, coal is a combustible, solid stratified rock of organic and mineral matter. The organic matter constitutes carbon (60 to 90 per cent), hydrogen (one to 12 per cent), oxygen (two to 20 per cent), nitrogen (one to three per cent) and also small amounts of phosphorus and sulphur. Coal occurs as a sedimentary rock in association with carbonaceous shale, sandstone and even fireclay in a regular succession and in repetitions. Gondwana coal is found as drifted deposits and tertiary coal occurs as in situ deposits.

Coal originates from the accumulation of vegetable matter in swampy areas on broad delta, coastal plains and basin lowlands. The vegetable matter is subjected to geo­logical processes that effect physical and chemical changes. The changes can be seen in the darkening of colour, increase in compactness, hardness and carbon content, and decrease in volatility and moisture. The growth in situ and drift theories explain the origin of coal. The complex process of coal formation involves physical and bacteriological agencies. Favourable climatic conditions for coal formation are mild temperature to sub-tropical climate with well­-distributed moderate to heavy rainfall.

Stages of Coal Formation Peat is the first stage of coal formation and varies considerably in extent and thickness. It has a high percentage of moisture and volatile matter. Carbon makes up only about one-third of its bulk.

Anthracite, the hardest variety, ranks highest amongst the coals. It has a carbon content of almost 95 per cent with practically no volatile matter. Only about 5 per cent of the world's coal is anthracite.

Economic Uses Coal, a primary source of heat and power (thermal power), is used in the production of water­gas; in metallurgical operations for the purpose of extrac­tion of metals like iron, zinc, etc.; in the production of coal gas, tar, coke, etc.; and to produce different types of varnish and germicides.

Distribution of Coal in the World Fenno-Scandinavia is one of the main deposits of peat in the world. Take (A) on P 196 of GS. The world's 50 per cent of anthracite comes from the Pennsylvanian fields of the USA. Russia, Ukraine, Kyrgyzstan and Kazakhstan account for another 25 per cent.

In overall coal production, China and the USA together contribute about 60% of the total coal production in the world. China has been the main coal producing country
in the world since 1986. Here, coal is mined mainly in the north in Inner Mongolia, Shansi, Anhui, Jiangsu, Henan and Hegei regions. In USA, coal mining showed a decline after the Second World War due to subsidised oil and gas prices, development of nuclear energy and environmental restric­tions, but it picked up after the oil crisis of the 1970s. Mining in USA is done mainly in the Appalachian region and in the interior stales.

In erstwhile USSR, major coal producing regions are Kuznetsk in Karganda, Kuzbas basin, Pechora basin, Donbass region and Tungus basin. In Europe, coal is mined in'Franco-Belgian coalfields, in Ruhr, Saar, Silesia, Pilsen, Saxony in Germany and in Poland, UK, Spain and the Central French Plateau.

Distribution of Coal in India In India, coal belongs to two principal geological periods, i.e., the lower Gondwana coals of Permian age, and Tertiary coals of Eocene to Miocene age. The greatest period of coal formation in India is the Permian. The important coal bearing formations are collectively known as Damudas and belong to the lower Gondwana system. The series of coal formations are Peat­lignite-bituminous-Anthracite. The lower Gondwana coals account for more then 90 per cent of the annual production of coal which is generally of bituminous rank. In Tertiary coalfields, lignite predominates.

The Gondwana coals are largely confined to the river valleys like those of the Damodar, Mahanadi, Godavari, etc. Tertiary coals principally occur in Assam, in the Himalayan foothills of Kashmir and in Rajasthan (Palna in Bikaner) in Eocene strata. Besides these, lignite deposits are found to occur in the South Arcot district of Tamil Nadu, in Kutch of Gujarat and also in the state of Kerala. The Neyveli lignite field of Tamil Nadu (which is of the Miocene Age) is the largest lignite deposit in South India.

Major Coal Fields The statewise list of major coal fields is given below.
West Bengal Raniganj.

Jharkhand Jharia, Bokaro, Giridih, Karanpura, Ramgarh. Madhya Pradesh Singniuli, Pench Valley. Chhattisgarh Korba.

Orissa Talcher, Himgir.

Andhra Pradesh Kantapalli, Singareni.

Tamil Nadu Neyveli (lignite).

Assam Namchik~Namphuk, Makum, Najira, Janji.

Meghalaya Umralong, Darrangiri

Production India at present is the fifth largest producer
of coal in the world. Coal is also India's largest mineral resource. Given our large coal reserves and the high cost of importing alternative fuels, it is important to develop advanced utilisation techniques and minimise environmen­tal dCKr'adation.