Transformation and Characterization of Cement Clinker Prepared from New Structured Red Mud by Sintering

Sodium aluminosilicate hydrate is the main equilibrium solid phase of Bayer red mud. Owing to the alkaline insoluble phase, the saltpetering of Bayer red mud tends to occur over time, even after washing procedures. This prevents the large-scale utilization of Bayer red mud for the production of cement, brick, subgrade materials, etc. In this study, a new type of red mud (C-C residue), structured through calcification–carbonization treatment, was used to produce cement clinker. The mineral transformation was studied and the phase, micromorphology, chemical composition, f-CaO content, bending strength and compressive strength of the clinker were characterized. The results show the transformation of C-C residue into the effective components (Ca3SiO5, Ca2SiO4, Ca2FexAl2–xO5 and Ca3Al2O6) of the cement clinker. The chemical composition, f-CaO content and cement strength met the Chinese national standards. Therefore, sintering C-C residue provides a promising solution to the problem of red mud stockpiling.