Analysis of the effect of syenite alkali aluminium concentrate (SAAC) on the properties of ceramic products containing the centrifugation waste of a mineral wool melt

Abstract

This study analysed the effect of the additive syenite alkali aluminium concentrate (SAAC) on the mineral composition, microstructure and physical and mechanical properties of ceramic products produced from low-melting illite clay when the traditional concentration of reducing additive sand was replaced with the centrifugation waste of a mineral wool melt. The SAAC additive was characterised by large contents of alkali oxides (Na2O+K2O=19.50%) and exhibited an average particle size of 9.8 μm. Formation masses were prepared by incorporating 20% of the centrifugation waste of the mineral wool melt and 5–20% of the SAAC additive and by burning at temperatures of 1000–1080 °C. The investigations performed show that during the thermal processing, when the SAAC additive melted, a liquid phase was created, and the active ions K+ and Na+ diffused into the ceramic matrix, thereby resulting in a change in the mineral composition of the ceramic body and the crystallisation of newly created minerals (e.g., leucite and labradorite). It was determined that the SAAC additive affected the microstructure (i.e., the open porosity decreased, and the closed porosity increased) and the physical and mechanical properties (i.e., density, water absorption, compressive strength) of the ceramic body.