- Steam drying of coals has the potential of developing the overseas market for low-rank coals. It would reduce the moisture content and there is a possibility of reduction of spontaneous combustion. This would make export of low-rank coals economically feasible. Use of hot water drying would also make the use of coal-water slurries made from low-rank coals compete with those made from higher rank coals for use in slurry-fed gasification and combustion facilities. Steam and hot water drying of low rank coals was carried out at saturated steam pressures between 220 and 330 degree C to study moisture reduction.