Study of phase transformation of calcium silicate using desert sand as raw materials

Abstract

Production of Portland cement consumes a huge amount of silica mineral. The present work aims to introduce desert sand to replace the natural mineral to achieve green manufacturing of silicate cement clinker, as well as further decreasing the synthesis temperature and increasing the production efficiency. The effects of desert sand, industrial quartz and high-purity quartz as raw materials, and Al₂O₃ and Fe₂O₃ as additives on phase transformation and microstructure of calcium silicate powder were comparably investigated using X-ray diffractometer, differential scanning calorimeter, and scanning electron microscopy. Results show that the main phases of all samples with different raw materials and additives were 3CaO·SiO₂ (C₃S) and 2CaO·SiO₂ (C₂S). In which, the samples prepared using desert sand had the lowest phase transformation temperature for C₂S and C₃S. When adding Al₂O₃ and Fe₂O₃, the phase transformation temperatures of C₂S and C₃S further decreased, which were 1032.5°C and 1270.9°C, respectively, meanwhile phase content reached the maximum (C₂S of 65.6 wt.% and C₃S of 61.2 wt.%). In addition, the most uniformly and finely distributed crystalline phases formed at an optimal calcination temperature of 1350°C. This is beneficial for reducing production costs, saving mineral resources, and promoting the sustainable development of the cement industry.