Abstract: A method of upgrading coal is disclosed, the method comprising: subjecting the coal to a hydrothermal dewatering process at a temperature and a pressure above ambient conditions to produce dewatered coal; removing ash tailings from the dewatered coal to produced reduced ash dewatered coal; and producing a coal water slurry with the reduced ash dewatered coal. An apparatus for upgrading coal is also disclosed, the apparatus comprising: a hydrothermal dewatering reactor connected to receive coal and output dewatered coal; an ash separator connected to receive dewatered coal from the hydrothermal dewatering reactor and output reduced ash dewatered coal; a slurrifier connected to receive reduced ash dewatered coal from the ash separator and output a coal water slurry.