Method and apparatus for separating out gall during glass melting processes

摘要

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.