利用亚硫酸钙型脱硫石膏制备胶凝材料的研究

摘要

以亚硫酸钙型脱硫石膏（CSDG）为原料，通过煅烧和添加改性剂（粉煤灰、明矾和无水Na2SO4）制备石膏基胶凝材料。研究了CSDG煅烧氧化过程，利用正交实验研究了改性剂加入方式、改性剂掺量、煅烧温度对胶凝材料强度的影响，并通过DTA-TG、SEM和XRD分析了影响胶凝材料强度的机理。结果表明，CaSO3在空气中488℃可被氧化为CaSO4；CSDG与改性剂混合后煅烧制备的胶凝材料，比CSDG单独煅烧再掺入改性剂的胶凝材料各龄期强度明显提高；粉煤灰掺入量是影响强度的关键因素；CSDG与改性剂混合煅烧制备胶凝材料的适宜工艺参数为煅烧温度700℃，粉煤灰掺入量30%，明矾3%，无水Na2SO41%。CSDG与改性剂混合煅烧，Ca(OH)2和硫酸盐在高温下活化了掺入的粉煤灰，因而使胶凝材料的强度明显提高。%The gypsum-based cementing material was prepared by calcining and adding modiifer(lfy ash, alum and Na2SO4) using calcium sulifte desulfurization gypsum(CSDG) as raw materials. The oxidation effect of CSDG during calcination process was studied and the inlfuence of the adding style, adding amount of the modiifers, and temperature of calcination were studied by orthogonal experiment. The strength enhanced mechanism was analyzed by DTA-TG, SEM and XRD. The results show that CaSO3 can be oxidized into CaSO4 at 488℃. The strength of the gypsum based cementing material prepared by mixing CSDG and modiifer before being calcined is much higher than that prepared by mixing calcined CSDG and modiifer after the CSDG was calcined alone at any hydration ages. The amount of lfy ash has an important effect on the strength of the gypsum-based cementing materials. The proper preparation parameters are listed as follow: the heat temperature is 700℃ and the amounts of lfy ash, alum and anhydrous Na2SO4 are 30%, 3% and 1%, respectively. The strength of cementing material was improved signiifcantly due to the activation of lfy ash by Ca(OH)2 and sulfate together under high temperature.