Abstract:To investigate the feasibility of utilizing chlorite-quartz schist (CQS) as a substitute for conventional siliceous-aluminous raw materials in the production of Portland cement clinker, this study systematically examined the effects of CQS content (0%–8%) and calcination temperature (1300–1450 °C) on the burnability of raw meal, the mineral composition of clinker, and the resulting cement properties. The results indicate that CQS exhibits superior grindability compared to sandstone and meets radiological safety requirements. An appropriate addition of CQS significantly reduces the free calcium oxide (f-CaO) content in the clinker and improves burnability, with the optimal performance achieved at 1400 °C with a CQS content of 4%. The prepared cement meets the 42.5-grade strength requirements of the national standard at both 3 and 28 days. Mechanistic analysis reveals that CQS enhances clinker formation through a synergistic effect: the decomposition of chlorite provides highly reactive SiO?, while trace elements such as F and K exert a composite mineralizing effect. However, excessive incorporation of CQS leads to the solid solution of Mg2? and F? ions, which induces a transformation of C?S from the highly active M1 polymorph to the less active M3 polymorph, thereby affecting the later-age strength development. This study provides a theoretical foundation for the resource-efficient utilization of CQS in the cement industry.
