Fuel Processing Technology, Vol.45, No.1, 11-25, 1995
EXTRACTION OF ASSAM COAL THROUGH STEPWISE ALKALI TREATMENT UNDER AMBIENT-PRESSURE CONDITIONS
A process for the stepwise alkali treatment of coal under mild conditions using phenol as a solvent has been developed. About 70% of Assam coal was rendered extractable through three alkali treatment steps in hot phenol followed by quinoline extraction at each step. The stepwise alkali treatment of Assam coal alternately in tetralin followed by that in phenol rendered 56% coal extractable. Stepwise alkali treatment of coal could be of considerable interest for structural studies on coal. Alkali treatment also breaks, disrupts, and reforms various associative forces and entanglements between the coal macromolecules to render these extractable in quinoline. The stepwise alkali treatment holds the promise of being developed as a unit process to obtain a clean fuel.