脱硫石膏制备半水石膏晶须的研究

Research on preparation of hemihydrate gypsum whiskers from desulfurized gypsum

脱硫石膏是电厂湿法烟气脱硫的固体废弃物,不仅造成资源浪费,还会对环境产生污染。为提高脱硫石膏的附加值,以脱硫石膏为原料,采用盐溶液法制备半水石膏晶须,研究了氯化钠浓度、温度、液固比、p H对转化率的影响,并研究了柠檬酸的含量对形貌的影响。采用傅立叶变换红外光谱仪（FTIR）、X射线衍射仪（XRD）、扫描电子显微镜（SEM）等对制备的半水石膏晶须做了表征,并研究了柠檬酸对形貌影响的机理。研究表明：当氯化钠质量分数为20%、反应温度为100℃、液固比为5∶1、反应时间为2 h、柠檬酸的质量分数为0.25%时,可制备出长度为50~100μm、长径比为（30~50）∶1的半水石膏晶须。

Desulfurized gypsum is the solid waste from wet flue gas desulfurization technology of power plants.It can not only waste valuable resources,but also pollute the environment.In order to promote the added-value of utilization,hemihydrate gypsum whiskers were prepared by salt solution method and using desulfurized gypsum as materials.The influences of the concentration of sodium chloride,reaction temperature,ratio of liquid to solid,and p H on conversion rate and the effect of the content of citric acid on morphology were investigated.The hemihydrate gypsum whiskers were characterized by scanning electron microscopy,X-ray diffraction and infrared spectroscopy instruments.The mechanism of the effect of citric acid on the morphology was also studied.The results showed that the best technological conditions were as follows：mass fraction of sodium chloride was 20%,reaction temperature was 100 ℃,reaction time was 2 h,ratio of liquid to solid was 5∶1,and mass fraction of citric acid was 0.25%.Under the optimal conditions,the length of hemihydrate gypsum whiskers was 50 ~100 μm and the slenderness ratio was（30~50）∶1.