Vitrification of waste materials

Abstract

The vitrification by mehing processes is the only technical process for safe immobilization and destruction of environmentally dangerous components in waste materials. Toxic filter dusts, which are produced in incineration plants, serve as an example of such wastes. The principal problems of all vitrification methods developed are the wide composition Variation of the input materials, t h e risk of new filter dust formation by necessary flue gas cleaning plants, especially of sulphur Compounds, the lack of knowledge of the melting behaviour, and achieving chemical long-term stabihty of the resulting waste glasses. Melting experiments with model Systems show that the typical composition ränge of incineration filter dust allows synthesis of resulting glasses without addition of other materials. With a carbon content of more than 5 wt% the glasses are black. The formation of galt and the loss of sulphur by evaporation in the glasses decrease with increasing contents of carbon and the number of metals which support the formation of metal sulphide groups in the glass. The legal limits of the long-term leaching stability are observed for copper and zinc. By the results of the research project it has become possible t o produce waste glasses which can be processed to new glass products.