Sintering characteristics of BCSAF cement clinker with added wastes from production of manganese and magnesium metals

The production of belite-calcium sulfoaluminate-ferrite (BCSAF) cement with the addition of industrial wastes as feedstock has been studied for many years. The preparation of clinkers is essential in cement production, in which all raw materials react with each other to generate key phases in cement under some specified conditions. The objective of this study was to investigate the sintering characteristics of BCSAF cement clinkers. Four BCSAF clinkers with different compositions were examined. High-temperature microscopy, quantitative x-ray powder diffraction analysis and scanning electron microscopy were used to analyse sintering features and phase composition. The results show that the use of wastes from the production of manganese and magnesium metals, which were added to the raw materials to make clinker pellets, can significantly reduce the firing temperature of BCSAF clinker. The firing temperatures of clinkers with added wastes were below 1300°C, much lower than the temperature used for conventional Portland cement (1450°C). The ferrite phase was always found to inter-grow with the $C4A3S¯$ phase or C₂AS phase, just like the interstitial phase. The ferrite phase acted as a solid solution during cement sintering. A small quantity of iron oxide can make the clinker more porous, leading to energy savings in subsequent grinding processes.