Ammonium alum is manufactured by boiling bauxite- sulphuric acid liquor with ammonium sulphate [(NH4)2] and crystallizing it where coal is used as a fuel. Besides the above BIS specifications, the plant produces ferric alums of different qualities according to the customers demand. This is the only plant which produces all the three types of alums in Assam. The plant is designed and installed to produce 6000 MT Ferric Alum, 6000 MT Non-ferric alum and 1000 MT Ammonium alum per annum.