Abstract: A method and apparatus for thermal decomposition of stable substances, preferably chemical hazardous waste. The invention achieves a high decomposition temperature by giving the waste the necessary decomposition temperature through the use of a plasma generated in a plasma burner. The waste itself can be carried through a plasma generator. Alternately, part, or all of the waste can be mixed with the plasma in a reaction chamber where decomposition takes place. The carrier gas of the plasma can be given a temperature of 3000.degree. to 4000.degree. C., or under certain conditions even a higher temperature. The invention also includes additional steps to eliminate toxic gases that might form during the decomposition of the waste or the cooling of the resultant gases.

Abstract: A plant comprising a post combustion chamber (1) connected to the combustion chamber of a household rubbish incineration furnace whose hot gases it uses in order, by means of suitable burners (2, 3), to heat sewage sludges and industrial liquids and a circuit for the treatment of the smoke and residues coming from said post combustion.This circuit, which is held under vacuum by a blower (27), comprises a dry cooling tower (7) employing semi-liquid sludges as cooling agent, an absorption tower (15) employing a solution adapted to combine the predominantly acid gases of the smoke, and a separating tower (22) in which the liquids in suspension are removed.A recycle circuit (190) for the solution and liquid separated and means of recovering metallic particles and compounds (10, 12, 29) complete this plant.