Thermal technologies to convert solid waste residuals into technical glass products

Abstract

Solid waste residuals f r o m waste incinerator flue gas cleaning Systems consist of various oxides, alkali halogenide salts, heavy metal Compounds and traces of organic pollutants. After the Separation of the volatile components from the oxides and the complete destruction of the organics by a thermal treatment at a temperature υ > 1200°C, the remaining oxides are obtained as a homogeneous black glass ready for the direct reuse as a filling or stabilizing material, the production of glass-ceramics by a further thermal processing and/or the use as a secondary raw material for the production of technical glass products, e.g. glass wool, glass fibre or foam glass. For the determination of the reuse potential of the vitrified wastes, basic material parameters have to be determined and compared with Standard glasses. Under this aspect the chemical resistance in acids, bases and water, the density, the hardness, the elasticity, shear and compression moduli, the Poisson's ratio, the bending strength, the dielectric permittivity a nd losses, the refractive index, the optical reflectivity and absorption behaviour, the thermal expansion coefficient, the thermal conductivity and heat capacity were determined for vitrified electrostatic precipitator ash from municipal solid waste incineration plants. The results of these studies, compared with those obtained for Duran, showed a low leachability in neutral and alkaline media a nd good electrical, mechanical and thermal properties. Tests to transform the as-received glasses into glass-ceramics were carried out. Preliminary recrystallization experiments led to dark brown to black-coloured, partially recrystallized glass samples.