Abstract: A method and apparatus for incinerating loose waste material in which the loose waste material is introduced into a furnace chamber to form a layer in the bottom of the furnace chamber. The layer of loose waste material is subjected to the direct action of technical-grade oxygen, preferably in less than stoichiometric amounts, with the oxygen fed at least at the speed of sound. The oxygen is supplied utilizing a plurality of lances distributed in the furnace chamber. Heat produced by combustion of the waste material melts incombustible constituents of the waste material. Residual unburnt combustible gases can be fed through an outlet stack to a secondary combustion chamber.