The effect of granulated lead–zinc slag on aesthetic and microstructural properties of single-fired wall tile glazes

Abstract

Recycling of industrial wastes could reduce environmental pollution and decrease final production costs for the relevant sectors. Some of the solid wastes originating from metal production industries, including slags, scraps or powders, have been recently recognised as potential secondary raw materials to use in ceramic and glass industries for the production of pigments, bodies or glazes. The aim of this study is to produce some pigments from granulated waste slags obtained from lead–zinc smelting furnace for industrial ceramic glaze application. The chemical and phase analysis of slag is characterised by X-ray fluorescence (XRF) and X-ray diffraction (XRD), respectively. The wastes are calcinated to investigate the colour effect of synthesised pigments in industrial wall tile glazes. After addition of 5, 10 and 15 wt% of Fe2O3 to the slag, the samples were calcinated at 1150 °C and then added to the glaze composition in 3, 6, and 9 wt%, respectively. The glazes were applied to the engobed wall tiles and single fast fired at 1112 °C for 45 min. After performing colour analysis on glazed surfaces, phase analysis was carried out by X-ray diffractometer (XRD). Thermo-mechanical analyses (TMA) were done to determine the coefficient of thermal expansion (α). Increasing the proportion of slag in the glaze formulation resulted in the colour tone change of the final surfaces from cream to dark brown.