Abstract: Process for vitrifying environmentally hazardous waste material in a glass melting furnace includes forming a batch including the waste material and no more than 30 weight percent additives including phonolite and SiO.sub.2 containing substances. A gall layer 2-5 cm thick including alkali salts or alkaline earth salts is produced on the molten glass, and batch is added so that a batch layer over 5 cm thick is formed on top of the gall layer. After the batch layer is formed, the molten glass is heated solely by electrodes, and the thickness of the batch layer is maintained to produce a steep enough temperature gradient therein so that the furnace atmosphere remains relatively cool, and substantially all of the condensable components which emerge from the molten glass condense in the batch layer.

Abstract: Apparatus includes a furnace for vitrifying waste material, a storage container for delivering waste material to the furnace and a pipe for passing a heat transfer medium through the storage container to preheat the waste material and remove water therefrom. The pipe may be a pipe through which exhaust gas is passed or a pipe through which a liquid medium is passed after heat transfer from the exhaust gas. The apparatus further includes means for removing dust from the exhaust gas and heating same to break down dioxines and furanes therein.

Abstract: Furnace has a melting section and a withdrawal section bounded by side walls of refractory material which extend to a glass outlet formed by an overflow edge remote from the melting section. In operation a molten glass layer, a molten layer of undissolved sulfates, and a batch layer succeed one another from the bottom up in the melting section. The withdrawal section is separated from the melting section by a first dividing wall extending downwardly and terminating above the surface of the molten glass. A second dividing wall is disposed for the formation of an underside glass passage, and at least one closable opening for withdrawing the molten sulfates is disposed at the level of the sulfate layer between the first and second dividing walls. The opening has a bottom boundary whose height is adjustable, so that it can be adjusted to lie above the surface of the glass melt.

Abstract: Waste substance such as incineration ash is mixed with cullet and alkaline earth salt to form a mixed batch which is added to a glass melt heated solely by electrodes, producing an exhaust gas which is introduced into the batch thereby cooling the gas to produce condensation products. The alkaline earth salt reacts with alkali in the gas and the condensation products to produce a gall layer of alkali salts and alkaline earth salts which serve as a melt accelerator and are readily removed when accumulated. According to a further step the gas is purified by separating dust therefrom and introducing it into the batch as a slurry.