Preparation and Properties of Glass from Sewage Sludge Slag

Abstract

Glasses were prepared bymelting the sewage sludge slag, and the relation between the properties and the chemical composition of the glasses, especially, the ratio of Fe²⁺/ (Fe²⁺+Fe³⁺) was analyzed in detail. The glasses were dark brown and not transparent due to high concentration of iron oxide. It was found that the properties of the slag glass were similar to those of aluminosilicate glasses which are available commercially. It was possible to control the ratio of Fe²⁺/ (Fe²⁺+Fe³⁺) in glass by adding graphite powder to the raw materials of glass. It was found that, as the fraction of Fe²⁺ion increases, the thermal expansion coefficient increases, density decreases, glass transition temperature decreases and viscosity also decreases.