Tata Steel Limited

Pinakpani Biswas

Pradip Kumar Banerjee

Vimal Kumar Chandaliya

A method of recovery of organic solvents required in the refining of coal comprising: mixing solvent, co-solvent and coal to form a slurry; thermally treating the slurry under pressure and high temperature to form a coal-extract; passing the coal-extract through a membrane under high pressure in an ultra filtration unit to achieve recovery of a major part of the solvent; contacting the remaining thick clarified liquid from the membrane with water to obtain precipitated coal in a slurry with a mixture of water and organic solvent; feeding the slurry to a filter to get clean coal of very low ash content as a residue and a mixture of water and organic solvent as a filtrate; distilling the filtrate to separate the balance of the organic solvent from the water. The application of a membrane for filtration minimizes the heat requirement to establish economy.

Method of recovery of organic solvents required in refining of coal

A process to produce low ash clean coal from high ash coal with substantially complete solvent recovery, the process including: forming a slurry of coal fines in a N-Methyl-2-pyrrolidone (NMP) and Ethylenediamine (EDA) solution; maintaining said slurry in a reactor at a temperature range of 100&#xb0; C. to 240&#xb0; C. and a pressure range of 1 to 4 gauge (kg/cm2) for a period of about 15 minutes to 4 hours; separating the produced sample withdrawn from the reactor, one part being a filtrate and the other a reject; feeding the filtrate into an evaporator to recover 80-85% solvent; precipitating the concentrated filtrate material in an anti-solvent tank to separate coal from solvent; separating the coal by filtration, said separated coal having a reduced ash content; feeding the anti-solvent and solvent mixture into a distillation column to separate remaining solvent from the anti-solvent for reuse in the process.

Process for production of low ash clean coal from high ash coal with total solvent recovery

An improved organo-refining process to produce low ash clean coal from high ash coal, comprising: mixing coal, solvent and a co-solvent to produce a slurry; feeding the slurry to a reactor by pumping; extracting a coal-solvent mixture from the reactor; feeding the extracted mixture to a flasher unit; recovering about 30% of the solvent from the flashing unit; feeding the remaining heavy material to an evaporator; extracting about 60% of solvent from the evaporator; discharging the residue from the evaporator to a precipitator having water which produces a coal slurry; filtering the slurry in a rotary drum; collecting the super clean coal as a residue and feeding the filtrate into a distillation unit; and separating the water and the organic material in the filtrate to recover at least 7 to 8% of the remaining solvent.

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Jamshedpur, India

Pinakpani Biswas