Abstract: A process for treating coal to obtain lower ash content coal including: (i) pretreating high ash coal in a pretreatment unit with ultrasonic waves or microwaves, (ii) forming a slurry of coal fines in a solvent solution including N-Methyl-2-pyrrolidone (NMP) and one of Ethylenediamine (EDA) or Monoethanolamine (MEA), (iii) maintaining said slurry in a refluxed condition at a temperature of about 170-190° C. for a period of about 15 minutes to 2 hours; (iv) separating the refluxed slurry into two parts consisting of extract and residue by coarse filtration, (v) recovering up to 85% of the solvent solution by evaporation of the extract to form a concentrated extract, (v) precipitating the coal by adding water to the concentrated extract, (vi) separating the coal from the water-extract solution by filtration, and (vii) recovering the rest of the solvent by distillation of the water-extract solution.

Abstract: A process for treating coal to obtain lower ash content coal including: (i) pretreating high ash coal in a pretreatment unit with ultrasonic waves or microwaves, (ii) forming a slurry of coal fines in a solvent solution including N-Methyl-2-pyrrolidone (NMP) and one of Ethylenediamine (EDA) or Monoethanolamine (MEA), (iii) maintaining said slurry in a refluxed condition at a temperature of about 170-190° C. for a period of about 15 minutes to 2 hours; (iv) separating the refluxed slurry into two parts consisting of extract and residue by coarse filtration, (v) recovering up to 85% of the solvent solution by evaporation of the extract to form a concentrated extract, (v) precipitating the coal by adding water to the concentrated extract, (vi) separating the coal from the water-extract solution by filtration, and (vii) recovering the rest of the solvent by distillation of the water-extract solution.