盐酸法副产物氯化钙废液制备碳酸钙晶须的研究

Study on preparation of calcium carbonate whiskers with spent liquor of calcium chloride as byproduct from hydrochloric acid method

以盐酸法湿法磷酸工艺中产生的副产物氯化钙废液为原料,采用碳酸钠为沉淀剂,在常温下直接进行了碳酸钙晶须的制备研究。研究了反应时间、氯化钙浓度对碳酸钙晶须长径比的影响以及碳酸钠加入量对碳酸钙晶须产率和纯度的影响,并采用电子扫描电镜(SEM)照片和X射线光电子能谱分析(XPS)对试验结果进行了分析,结果表明:碳酸钙晶须的长径比随反应时间的延长先增后减,当反应时间为110min时,长径比达最大值;而随着氯化钙浓度的增加,碳酸钙晶须的长径比减小;碳酸钠的加入量对碳酸钙晶须的纯度影响不大,当碳酸钠以碳酸钠与钙离子的摩尔比为1.06∶1加入时,碳酸钙晶须的产率达99%。制得的碳酸钙晶须晶型完整,没有颗粒状的碳酸钙存在。

Study was conducted on direct preparation of calcium carbonate whiskers at room temperature with sodium carbonate as precipitator using spent liquor of calcium chloride as byproduct produced in the hydrochloric acid wet method and phosphoric acid process. The study covered influence of reaction time and calciumchloride concentration on length-diameter ratio of calcium carbon- ate whiskers and influence of addition of sodium carbonate on pro- ductivity and purity of calcium carbonate whiskers. Analysis of the test results by the electronic scanning electron microscope （SEM） photo and X-ray photoelectron spectroscopy （XPS） showed that the length-diameter ratio for calcium carbonate whiskers first increased and then decreased with extension of the reaction time. When the reaction time is 110 min, the length-di- ameter ratio reached the maximum value and with increase of cal- cium chloride concentration, the length-diameter ratio for calcium carbonate whiskers decreased. Addition of sodium carbonate ex- erted no great influence on purity of calcium carbonate whiskers. When addition of sodium carbonate was made at mol ratio of sodi- um carbonate and calcium ion being 1.06 ： 1 , the productivity ratio for calcium carbonate whiskers was up to 99% and the crys- tallographic form of calcium carbonate whiskers grows in integri- ty with no existence of granular calcium carbonate.