Synthesis of portland cement clinker at low temperature using raw materials from western Mongolia

This study evaluates gypsum-assisted low-temperature synthesis of Portland cement clinker using limestone, marlstone, iron ore, and natural gypsum from Western Mongolia. A raw mix designed by Kind’s method (LSF = 0.93; SM = 2.2) was sintered at 1100–1300 °C with 0–2.0 wt.% gypsum addition, and replicated free-lime measurements were used to assess burnability. Increasing temperature markedly reduced residual free CaO, while moderate gypsum addition promoted CaO assimilation. Nonlinear regression identified, within the investigated range, an optimum near 1.39 wt.% gypsum at 1300 °C, corresponding to a predicted free-lime content of approximately 1.25 wt.%. XRD and SEM confirmed the formation of an alite-rich clinker with developed silicate phases. Cement produced from this clinker met the physical and mechanical requirements of MNS 0974:2008 for OPC 42.5 grade, confirming gypsum-assisted clinkerization as an effective route for promoting clinker phase formation at a reduced sintering temperature under the present experimental conditions.