水热合成-低温煅烧硫铝酸钙水泥熟料矿物的形成过程

Mineral Formation Mechanism of Calcium Sulphoaluminate Cement Clinker in Hydrothermal-Low Temperature Sintering Process

以水热合成-低温煅烧法制备低温型硫铝酸钙（C4A3$）-贝利特水泥熟料,用X射线衍射、热重-差热分析、扫描电镜等分析了水热合成产物种类、煅烧过程中矿物相衍变,进而分析C4A3$的低温形成机制。结果表明：90℃水热合成物的比表面积高达76 800 m^2/kg,煅烧时水化硫铝酸钙AFm和AFt在650℃生成C（12）A7,750℃开始形成C4A3$,于1 100℃形成完全,其形貌为五角十二面型聚体。煅烧过程中无明显SO3质量变化,且烧成温度比一步法低200~250℃。水热合成物及其高比表面积是C4A3$低温形成的主要原因,而低温烧成是低硫排放的主要因素。

The low-temperature type calcium sulphoaluminate（C4A3$）-belite cement clinker was prepared via hydrothermal synthesis-low-temperature calcination. The hydrothermal synthesis products and minerals during the calcination of clinker were analyzed by X-ray diffraction, thermogravimetric analysis/differential scanning calorimetry, and scanning electron microscopy, respectively, and the formation mechanism of C4A3$ with low-temperature characterizations was discussed. The results show that the specific surface area of hydrothermal product in hydrothermal reaction at 90 ℃ is 76 800 m^2/kg, C（12）A7 appears at 650 ℃ due to AFm and AFt（i.e., hydrated calcium sulphoaluminate）, C4A3$ begins to form at 750 ℃, and C4A3$ completely forms at 1 100 ℃. The morphology of C4A3$ is pyritohedron, and the mass fraction of SO3 has little change in the calcination process. The clinker sintering temperature is 200~250 ℃,which is lower than that of the conventional direct calcination. C4A3$ formed at a low temperature is due to the presence of hydrothermal synthesis product with the great specific surface area, and the formation of C4A3$ at a low temperature is a main reason for the calcination process without sulfur emissions.