常压盐溶液法制备α-半水石膏的工艺条件研究

Study on the Process Conditions of Preparation of α-Plaster of Paris by Aqlueous Salt Solution Method in Atmospheric Pressure

二水石膏在盐溶液中部分脱水可制得高强度α-半水石膏。在确定媒晶剂的基础上,采用正交试验考察了热处理温度和时间、石膏浆料pH值、原料粒度等因素对常压盐溶液法制备α-半水石膏的抗压强度的影响,并对试验结果进行极差分析,得到了合适的工艺参数,结果为媒晶剂为柠檬酸钠与Al3+等的复合物(占盐溶液的质量分数为10%),热处理温度为100±1℃、热处理时间4h、石膏浆料pH值为4、原料粒度在172μm以下。在上述条件下,产品抗压强度可达44MPa。

High-strength α-plaster of Paris can be produced by dehydrating gypsum dihydrate partially in aqueous salt solution.After crystal modifier was chosen,Orthogonal test was designed to investigate the effects of temperature and time of heat treatment,pH value of gypsum slurry in water,gypsum ore grain size during the dehydration process on the compressive strength of product α-plaster of Paris after hydrated by Aqueous Salt Solution Method in atmospheric pressure.Range analysis was then employed to optimize the process conditions from the test results.The results of experiments were as follows:crystal modifier was the mixture of citric acid (or its ssalt),Al^3+ and other substance and the mass percentage of the mixture was 1.0%(in aqueous salt solution),heat treatment was 100±1℃,heat treatment time was 4h,pH value of gypsum slurry was 4,gypsum ore grain size was below 172 μm.Under these conditions above-mentioned,compressive strength of product could reach 44 Mpa.