Sintering of loose Pisha sandstone to prepare ceramic sand and mineral evolution response mechanism

To enhance the effective utilization of loose Pisha sandstone resources, this study introduces an innovative method for preparing ceramic sand from Pisha sandstone. Through comprehensive experimental analysis, the optimal sintering temperature was determined, and the mineral evolution processes during sintering were thoroughly investigated using FactSage thermodynamic simulation software combined with thermal analysis methods. Moreover, the influence of high-temperature liquid phase formation on the pore structure was analyzed, and the exact liquid phase content at the optimal sintering temperature was quantified. Results showed the optimal sintering temperature to be 1125 °C, yielding ceramic sand with a compressive strength of 5.29 MPa, bulk density of 964.3 kg/m³, and water absorption rate of 2.99 %, meeting the standards for 1000-grade lightweight fine aggregates. The formation of low-eutectic liquid phases involving feldspar, quartz, wollastonite, and diopside significantly reduced porosity and enhanced densification of the ceramic structure. The optimal liquid phase content at 1125 °C was precisely calculated as 85.48 %. This research provides a solid theoretical basis for developing new strategies to sustainably exploit Pisha sandstone resources, a major sediment source in the Yellow River basin.