EDTA滴定法测定萤石中氟化钙含量的方法改进

建立了EDTA滴定法测定矿石中氟化钙的方法。引入了钙乙酸为溶解试样的溶剂,溶解样品中的碳酸钙,同时,通过同离子效应减少氟化钙的溶解度。实验中探究了钙离子的浓度与氟化钙溶解度的关系,通过对比实验确定选择了含钙乙酸的最佳浓度(10g/L)。同时,对实验中的其他条件也进行了相应的探究与优化,确定最佳实验条件为:最小称样量为0.5g,洗涤沉淀用水量为50mL左右,第二次过滤时的洗涤次数为8～10次,滴定时加入氢氧化钾的量为20mL。方法的精密度(0.10%)和准确度(0.08%)皆能满足实验要求。

An improved method for determination of calcium fluoride in fluorite by EDTA titration

A method for determination of calcium fluoride in ore by EDTA titration was established. Calcium acetate was introduced as the solvent to dissolve the sample, calcium carbonate in the sample was dissolved, and the solubility of calcium fluoride was reduced by the same ion effect. In the experiment, the relationship between the concentration of calcium ions and the solubility of calcium fluoride was explored, and the optimal concentration (10 g/L) containing calcium acetic acid was determined through comparative experiment. At the same time, other conditions in the experiment were also explored and optimized, and the optimal experimental conditions were determined as follows: the minimum weighing sample size was 0.5 g. Washing and precipitation water consumption is about 50 mL; The washing times of the second filtration were 8~10 times.The amount of potassium hydroxide added in titration was 20 mL. The precision (0.10%) and accuracy (0.08%) of the method can meet the experimental requirements.