Coal Hydrophobicity and the settling behaviour of coal fines tailings

India is blessed with enormous coal reserves (one fifth of the world reserves) and is characterized as high ash and difficult to wash. With a 66% share of installed power generation capacity (255 GW, plus about 40GW captive power plants), the coal industry has a major role to play in the nation’s development. The coal consumption in 2013-14 was 643 MT against the indigenous production of 462 MT (mostly from Coal India Limited). The coal washing capacity from all the 52 washing plants is 131Mtpa, indicating that around 30% of the coal is being washed before it is used for power generation. It is envisaged that by the end of 12th five year plan coal washing capacity will be increased to 250 Mtpa. In India wet coal washing is usually practiced by crushing, sizing followed by beneficiation. The coal fines are usually recovered from the thickener, were flocculants are added to increase the settling of the coal fines. Normally, the coals are hydrophobic in nature and affect settling processes to a large extent. In the present paper four Indian coals of different characteristics are taken and their settling behavior in presence of industrial flocculent was investigated and correlated with the hydrophobicity of coal. Key words: coal washing, coal fines, effluents, contact angle, hydrophobicity, settling, flocculent, etc