Effect of talc on microstructure and properties of the graphite tailing stoneware tiles

Abstract The stoneware tiles were prepared from graphite tailings, kaolin, shale, potash feldspar and albite, and the firing temperature range was broadened by adding talc as an additive. The effects of talc on the phase compositions, microstructures and properties of the stoneware tiles were analyzed, and the mechanism for broadening firing temperature range of the stoneware tiles was studied. The results showed that sample B3 (60.87 wt% graphite tailings, 8.7 wt% kaolin, 8.7 wt% shale, 8.7 wt% potash feldspar, 13.04 wt% talc) fired from 1080 °C to 1100 °C exhibited better properties than other samples with the water absorption and the bending strength of 0.22% ∼ 0.48% and 88.04 MPa ∼ 93.54 MPa respectively. The performance meets the requirements of Chinese national standard “Ceramic Tiles” (GB/T 4100-2015). Based on the results of XRD, the phase compositions of the samples are quartz, anorthite, enstatite and hematite. Enstatite is a new phase compared with our previous study, due to the transformation of talc to enstatite. Talc can not only promote densification by reducing the high temperature liquid viscosity, but also broaden the firing temperature range of stoneware tiles by promoting the crystallization and growth of enstatite grains.