PURPOSE: To efficiently remove water in brown coal by heating a slurry consisting of the brown coal and a solvent under a press. above saturated vapor press and vaporizing water by flashing the heated slurry.

CONSTITUTION: After mixed with a solvent in a mixing tank 1, brown coal is crushed by a wet mill 2 such as a disk mill and sent to a slurry tank 3. The resulting slurry is pressurized through a pump 4 and, after heated to 200W300°C in a preheater 5 and a heater 6, depressurized through a first reducing valve 7 to vaporize and separate part of water in a first separator 8. Then it is depressurized through a second reducing valve 9 and the balance of the water is vaporized in a second separator 10 to obtain a slurry with decreased water content. Vapor separated in the first separator 8 is used as a heat source for the preheater 5 and the condensate is sent to an oil/water separator 12. The second separator 10 is operated at 100W120°C under about atmospheric press., and the separated vapor is cooled in a condenser 11 and the condensate is sent to an oil/water separator 12, in which oil entrained by distilled water is separated to be recovered as a solvent.