REPRODUCING METHOD FOR WASTE ORGANIC SOLVENT

摘要

PURPOSE: To suppress secondary waste production and recover an organic phosphoric acid ester and a diluent at high recover efficiency by bringing a waste organic solvent into contact with CO2 gas in a supercritical state and then lowering the pressure of the CO2 gas which extracts the organic solvent to critical pressure or lower and separating and recovering the CO2 . CONSTITUTION: A waste organic solvent containing an organic phosphoric acid ester and a diluent is put in an extraction tank 16 and heated. High pressure CO2 gas from a gas cylinder 11 is heated by a heat-exchanger 13 and after dust is removed by a filter 18, the pressure of the CO2 gas is heightened by a compressor 19 and furthermore the temperature of the gas is kept constant by a heat-exchanger 21 and then the gas is blown into the extraction tank 16. Consequently, the organic solvent is dissolved in the blown CO2 gas. The resulting CO2 gas is drawn out of a discharge pipe 22 and pressure is decreased by a pressure adjusting valve 26 and adjusted to be atmosphere pressure in a separation tank 23. The organic solvent dissolved in the gas is separated from CO2 gas and stored in the lower part of the separation tank 23. CO2 gas is sent again to the heat-exchanger 13 through a gas returning pipe 24.