Preparation of ferric-rich sulfoaluminate cement from solid wastes and characterization of its mineral formation process

Ferric-rich sulfoaluminate cement (FR-SAC) prepared from solid waste has attracted more and more attention. However, the mineral compositions of solid waste-based FR-SAC clinkers are changeful due to the complex composition of raw materials. In this study, the influences of mineral composition and impurities in solid wastes on the mineral formation of FR-SAC clinker were investigated. The results showed that mullite in fly ash and sodium aluminosilicate in red mud did not decompose but easily reacted with other raw materials to form FR-SAC clinker. Al₂(SO₄)₃ in galvanic sludge decomposed before the formation reaction of FR-SAC clinker. The insufficient SO₂ involved in the reaction should be noted. Besides, Na₂O and K₂O promoted the decomposition of CaSO₄ and the formation of C₄AF. Most of the TiO₂ formed CaTiO₃, resulting in the increase of gehlenite and the decrease of C₂S and CaSO₄. These results can reduce the error when these solid wastes were used to prepare FR-SAC.