氯化钙制备半水硫酸钙晶须的工艺研究

Study on preparation of hemihydrate calcium sulfate whiskers by calcium chloride

半水硫酸钙晶须是一种用途广泛,具有很高综合性能的高性价比无机材料。以氯化钙和硫酸钠为主要原料,利用浓盐酸调节pH,选择不同的晶型助长剂,采用常压酸化法制备半水硫酸钙晶须。通过单因素实验,探究了不同晶型助长剂、沸腾时间、静置时间、原料比例和pH对制备半水硫酸钙晶须的影响,并确定了最佳工艺路线。采用扫描电镜、热重分析、X射线衍射对产品进行表征分析。实验得到最佳工艺条件:采用十二烷基硫酸钠为晶型助长剂、氯化钙质量浓度为20 g/L、n(氯化钙)∶n(硫酸钠)=1∶5、沸腾时间为1 h、pH=2、静置时间为2 h。在此工艺条件下,以氯化钙为原料制备得到的半水硫酸钙晶须长径比达到50,产品外观呈现洁净白色,无杂质。

Hemihydrate calcium sulfate whisker is a high cost-effective inorganic material with wide range of uses and high overall performance.Hemihydrate calcium sulfate whiskers were prepared by atmospheric acidification method with calcium chloride and sodium sulfate as raw materials,by using concentrated hydrochloric acid to adjust pH,and different additives to promote crystallization.The optimum process conditions were determined by single factor experiment,and the influences of additives,boiling time,standing time,proportion of raw materials and pH on the products were studied.The products were characterized and analyzed by scanning electron microscope,thermogravimetric analysis and X-ray diffraction.The optimum process conditions： the additive was SDS,the mass concentration of calcium chloride was 20 g/L,the amount-of-substance ratio of calcium chloride to sodium sulfate was 1∶5,the boiling time was 1 h,the pH was 2 and the standing time was 2 h.Under these conditions,the slenderness ratio of the hemihydrate calcium sulfate whiskers prepared by calcium chloride could reach50,and the color of the products was pure white and without impurities.