Synthesis of low-temperature, fast, single-firing body for porcelain stoneware tiles with coal gangue

Coal gangue is a major industrial solid waste in China, causing great environment pollution. According to phase diagram theory, a low-temperature, fast, single-firing body mix for porcelain stoneware tiles was designed in the quaternary system CaO--MgO--Al₂O₃--SiO₂, using coal gangue as the main raw material. The coal gangue was from Baishan city, Jilin province and mainly composed of kaolinite and quartz. Mineralogical compositions and microstructures of some selected samples sintered at different temperatures were identified with X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results indicated that the optimal body mix was the one containing 34 wt% coal gangue sintered at 1170°C for about 1 h, with rupture strength of 43 MPa and water absorption of 0.22%. The main crystalline phases of the sintered body were quartz, anorthite and mullite.