Abstract: A liquid bath furnace, for burning pumpable wastes comprising hydrocarbon compounds and mineral substances, has primary and secondary combustion chambers, the walls of which are provided with La Mont boiler heating surfaces, and a post-combustion chamber. The heating surfaces are provided with heat-conducting cladding. In operation of the furnace, the wastes are fed to the primary combustion chamber, where the hydrocarbons dissociate and the mineral substances melt, a layer of the latter solidifying on the cladding in this chamber. An oil burner is used to regulate the primary combustion chamber temperature.