Development of the composition of matte glaze with usage of pharmaceutical glass waste for the production of porcelain stoneware

Abstract

The paper shows the prospects of using pharmaceutical glass waste for partial replacement of high-value frits in the glazes composition. According to the results of X-ray fluorescence spectroscopy, the glass wastes belong to the group of alkali-containing aluminoborosilicate glasses. The results of thermomicroscopic and dilatometry studies showed that the combination of industrial waste frits and glass waste allows obtaining coatings that, according to their technological characteristics, meet the conditions of porcelain stoneware high-speed firing. The conditions for the resource-valued glass waste use as part of porcelain stoneware tiles glazes have been established. This allowed to use their potential as efficiently as possible and to partially replace (within 15–30%) high-value frits. Combinations of waste glass and industrial boron-free frits with high crystallization ability due to the increased content of alkaline earth oxides (RO=22–34 wt.%) were studied to prepare opaque matte coatings. Glazes compositions have been developed, which under conditions of high-speed firing, form matte coatings due to the directed crystallization of phase’s complex (ZnAl2O4, Zn2SiO4 and CaAl2Si2O8). Ceramic granite with white color coating (brightness coefficient of 80–83%) that differs by "silky" mattness (mirror reflection coefficient of 31–42%), high heat resistance (10 or more heat changes) and abrasion resistance of III–IV class was obtained. The best results were observed when using matte glazes in a complex with engobe, which includes the same glass waste in the amount of up to 30 wt.%. This is in general ensures a high level of their utilization, a significant high-value raw materials saving and an energy costs reduction for fritting.