A process flow sheet for pre-treatment of high ash coal to produce clean coal

摘要

Disclosed is a process to produce low ash clean coal from high ash coal with substantially complete solvent recovery, the process comprising: (i) forming a slurry of coal fines in a solvent mixture of N-Methyl-2-pyrrolidone (NMP) with Ethylenediamine (EDA); (ii) maintaining said slurry in a reactor at a temperature range of 100°C to 240°C and a pressure range of 1 to 4 gauge (kg/cm2) for a period of 15 minutes to 4 hours; (iii) separating the produced sample after withdrawal from the reactor, separation cut size being variable depending on the particle size to be treated including application of the end product, a first part of the separated sample being a filtrate or extract and the second part being a reject; (iv) washing the reject obtained in step (iii) in an anti-solvent (such as water); (v) separating the washed reject obtained in step (iv) by filtration, said separated reject having a high ash content; (vi) feeding the extract obtained in step (iii) into an evaporator to recover 80-85% solvent and to obtain concentrated material; (vii) precipitating the concentrated material obtained in step (vi) into an anti-solvent tank to separate coal from solvent; (viii) separating the precipitated concentrated material of step (vii) by filtration to obtain separated coal, said separated coal having a reduced ash content; (ix) feeding anti-solvent and solvent resulting from step (vii) as a mixture in a distillation column to separate remaining solvent from the anti-solvent for reuse in the process.