Abstract: A method and a system for thermal dewatering and preheating aqueous mixtures for feeding glass melting plants when passing through a shaft-like container provided with heating elements disposed one above another in tiers. To avoid the feed material from becoming glued together or agglomerating in the preheaters while the feed material is heated by exhaust gases with separately guided exhaust gases and feed material, a) the uppermost tier heating elements are closed relative to the mixture and are kept above 100 C, b) the interface between the mixture and the atmosphere above the mixture is shaped and heated by the uppermost tier heating elements so that part of the thermal output is emitted to the atmosphere via the mixture, and c) as the mixture proceeds through the container it is heated by further heating elements to temperatures close to the glass melting plant feeding temperature.

Abstract: An electrode system for glass melting furnaces with a melting tank is provided with an electrode holder (9) installed above the melt surface (20) and this electrode holder (9) has a coolant supply (24) and a metallic electrode (7). This is connected to the electrode holder (9) by means of a coolable threaded connection (8), whereby the coolant supply (24) projects into the upper end of the electrode (7). In order to install the cooled threaded connection (8) in the furnace chamber and to fit a permanent sheath (31) made of mineral material round the upper, cooled end of the electrode (7) and to protect this sheath (31) not only against chemical attack, but against mechanical cracking-off, in accordance with the invention the coolable end of the electrode (7) is surrounded by the sheath (31) of ceramic material, that is at least partly installed in a protective casing (32) made from corrosion and heat resistant metal.

Abstract: An electrode system for glass melting furnaces with a melting tank comprises at least one electrode holder (9) installed above the melt surface for inserting electrodes (7) from above through the melt surface (20). A connection device (27) for connection of the coaxial electricity and water supplies between the electrode holder (9) and the electrode (7) is located between the electrode holder and the electrode, whereby the electrode holder (9) has a coolant supply (24) for a coolant, which extends into the electrode (7).

Abstract: A tank furnace for the inertization of non-flammable batch, which contains hazardous substances, metals and less than 10% by weight of carbon, by vitrification with glass forming aggregates by producing a glassy melt. The furnace has a batch charging device and a tank, on the rim of which a furnace crown rests, electrodes for heating the melt, a supply of oxidizing gases to the melt and, as an outlet for the melt, an overflow channel which can be heated. Nozzles are installed in the bottom of the tank to introduce oxidizing gases in order to reduce the eluate values, and the electrodes are immersed in the melt from above. It is preferable to install the nozzles at sloping sidewalls of the tank which slope upwardly and outwardly.

Abstract: An electrically heated tank furnace is used to melt glass whereby a floating gall layer is formed on the melt, in particular during the vitrification of hazardous materials such as asbestos, fly ash, filter dust, whereby the tank of the furnace is fitted with a discharge outlet for the melt and an overflow channel with an inlet for the gall. A stream of ascending gas bubbles is produced in the melt. In order to promote better and automatic draining of the gall the stream of gas bubbles is produced directly in front of the overflow channel which thereby maintains a layer of liquid gall in the overflow channel and a layer of molten glass retained by a weir on the bottom of the overflow channel. The temperature in the overflow channel is chosen to be above the melting temperature of the gall, whilst the bottom layer of glass is maintained at a temperature at which the viscosity of the glass is so high that the glass does not drain out the overflow channel.