Abstract: Granulated coals or cokes derived from coal, in sizes up to about 3/4 inch and containing ash matter with an initial deformation temperature below about 2,300.degree.F, are fed to a slow fluidized bed comprising relatively large particles of coke intermingled with roughly spherical ash agglomerates, maintained at about 1,900.degree.F to about 2,450.degree.F, and supplied with a gasification medium, for example, steam mixed with oxygen or air. A fast fluidized bed of coke fines is superimposed above the slow bed and is contiguous therewith. Gasification products are discharged together with relatively fine particles of coke, which are collected and returned to the fast bed. Ash agglomerates are withdrawn from the bottom of the slow bed via a standpipe leading to a slagging grate. Combustion of coke fines in a forehearth beneath the slagging grate creates slagging temperatures therein and at the grate. Molten slag falls through a taphole and into a pool of water, from which slag frit and water are discharged.