Extraction of coal through dilute alkaline hydrolytic treatment at low temperature and atmospheric pressure

Abstract

Assam coal was extracted with ethylenediamine (EDA) using batch as well as Soxhlet techniques. It was found to be further extractable in EDA after a first extraction step. Stepwise extraction of coal in EDA resulted in 44% extraction. Alkali treatment enhanced the extractability of coal in EDA. Two step (1.5%) aqueous alkali treatment followed at each step by EDA extraction, resulted in 50% extraction of coal. Various solvents were tried in the aqueous alkali treatment of coal. EDA, tetralin, phenol, quinoline, ethanol and butanol were found to give good results. The use of Na 2CO 3 and Ca(OH) 2 along with NaOH in the alkali treatment did not improve the extractability of the coal. Nonaqueous alkali treatment of coal in different solvents also resulted in an enhanced extraction. Phenol, tetralin and pyridine were found to be good reaction solvents for the treatment of coal using solid NaOH in these solvents.