赤泥和脱硫石膏制备高贝利特硫铝酸盐水泥熟料

Preparation of High Belite Sulphoaluminate Cement Clinkers Using Red Mud and Desulfurization Gypsum

以赤泥、脱硫石膏和石灰石等为原料,通过添加一定量的砂岩和高铝石,烧制了以硅酸二钙(C2S)、无水硫铝酸钙(C4A3S)和铁铝酸四钙(C4AF)等为主要矿物的高贝利特硫铝酸盐水泥熟料。研究了煅烧温度、煅烧时间以及原料配比等因素对熟料性能的影响,确定了最佳的煅烧温度为1 280℃,煅烧时间为30 min,低于普通硫铝酸盐水泥熟料100℃左右;并将烧成熟料按标准方法成型,水化至一定龄期后进行力学性能测试,其具有较好的早期强度,高贝利特的矿物组成(40%~60%)保证了后期强度的稳定增长,且C2S含量为45%~50%、C4A3S含量为25%~30%时具有较好的抗压强度,28 d强度可达48.2 MPa;其水化产物主要为钙矾石(AFt)和C-S-H凝胶,还含有少量的单硫型水化硫铝酸钙(AFm)和铝胶(AH3)。

The study aims to utilize red mud, desnlfuration gypsum and limestone as the raw material by adding a small amount of sandstone and bauxite to prepare high belite sulphoaluminate cement clinkers. And the main mineral phase of the cement clinkers are diealcium silicate （C2S）, calcium sulphoaluminate （C4A3S^-） and tetraealeium aluminoferrite （CaAF）. The affect of temperature, calcine time, the composition of raw materials and other factors on the performance of clinkers were investigated. The results revealed that the optimum firing conditions were calcined at 1 280℃ for 30 rain which is lower 100 ℃ than ordinary sulphoaluminate cement clinkers. The cement clinkers were molded according to the standard methods and the mechanical performance was tested after hydrated to a certain age. The cement clinkers tested showed excellent early compress strength performances and the steady growth of the late compress strength can be ensured because of high content of belite （40% -60% ）. And the cement clinkers showed the best compressive strength when the content of C2S is 45% -55% and the content of C4A3S^- is 20% to 30% . While 28 d compress strength can be up to 48.2 MPa. The main hydration products are ettringite （AFt） and C-S-H gel. Minor amount of monosulfate （AFro） and aluminium hydroxide （AH3） is also observed.