Abstract: A process for disposing of sewage sludge by heating and shearing an aqueous mixture of sewage sludge in a tubular-shaped processing means containing a plurality of rotating agitators to produce a pumpable aqueous slurry of sewage sludge. The aqueous slurry of sewage sludge is mixed with solid carbonaceous fuel or an aqueous slurry of solid carbonaceous fuel to produce a pumpable aqueous slurry of sewage sludge and solid carbonaceous fuel. The aqueous slurry of sewage sludge and solid carbonaceous fuel is heated in a first steam jacketed rotary disc mixing-heating means. Alternately, first and second hoppers are filled with said heated aqueous slurry of sewage sludge and solid carbonaceous fuel and cycled between a second steam jacketed rotary disc mixing-heating means; wherein while one hopper is being filled the contents in the other hopper are being dewatered. The thickened pumpable slurry is burned in a partial oxidation gasifier, furnace, boiler, or incinerator to produce a hot effluent gas steam.

Abstract: The hot effluent gas stream comprising H.sub.2 +CO and entrained molten slag from the partial oxidation of an ash-containing heavy liquid hydrocarbonaceous fuel, an ash-containing solid carbonaceous fuel, or mixtures thereof is passed in succession through a radiant or quench cooling zone, a metal gas transfer line and a convective cooling zone. By covering the metal surfaces of the gas transfer line or the gas transfer line and the convective cooler connected thereto with a high temperature resistant carbon-containing material, substantially no molten slag sticks to the metal heat transfer surfaces on the inside of the gas transfer line or to the surfaces of the gas transfer line and the convective cooler connected thereto which are contacted by the partially cooled gas stream leaving the radiant or quench cooling zones.