高强脱硫石膏砌块的制备及微观结构研究

Manufacturing and micro-structure of high strengthdesulfuration gypsum blocks

为解决电厂脱硫石膏资源化应用,利用自制煮压釜与浇注成型工艺制备高强石膏砌块.采用差热热重分析仪、X射线衍射仪(XRD)、扫描电子显微镜(SEM)等手段分析表征脱硫石膏化学转变过程、石膏砌块物相结构与微观形貌特征.结果表明:脱硫石膏在145～160℃经脱水转变为熟石膏;较自然养护,干法养护(14h/70℃)石膏砌块更易获得较高的力学强度;XRD与SEM结果表明:砌块主要含二水石膏和半水石膏两物相,组织结构中发育而成的柱状晶为石膏水化物,柱状晶与基体组织胶结形成牢固的复合界面,并通过柱状晶拔出机制获得较好的力学性能,表明脱硫石膏砌块高强特性与其组织中的复合结构密切相关.

The high strength gypsum blocks were fabricated by use of self-made autoclave and the casting process to promote the utilization of desulfuration gypsum waste from the coal-fired power plants.The chemical transformation of the gypsum waste,the crystal structure,the microscopic morphology and microstructure of the high strength gypsum blocks were investigated by DTA/TG,XRD and SEM.The results showed that the plaster of paris was generated by heating the gypsum waste at approximately 145~160 ℃.The gypsum blocks have achieved high strength after dry curing(14 h/70 ℃).The XRD and SEM analysis indicated that the gypsum blocks mainly contained two phases of CaSO4·2 H2 O and CaSO4·0.5 H2 O and the main composition of columnar crystal was the crystal hydrate,which distributed randomly and combined with the matrix firmly.The cross sectional morphology demonstrated that the pull-out phenomenon of columnar crystal was observed,indicating that the gypsum block reinforcement mechanism was closely related with the columnar grain structure.