Determination of total sulfur in fluorite by iodimetry with high temperature combustion
YANG Zhanju, DU Guodong, LI Jianhua, MA Fuyuan, SHEN Shenghai
Qinghai Xikuang Tongxin Chemical Co., LTD., Xining 811600, China
摘要：建立高温燃烧碘量法测定萤石中总硫含量的方法。采用铜粉为助熔剂与萤石样品混合，以氧气为载气，萤石样品在高温燃烧管式炉中于1 200℃加热燃烧，将萤石样品中的硫转化为二氧化硫，以酸性碘化钾-淀粉溶液吸收二氧化硫，用碘酸钾标准溶液滴定。实验条件：氧气流量为1.5～2.2 L/min；称样质量为500 mg；铜粉用量为1 000 mg。在选定的实验条件下，总硫测定结果的相对标准偏差为2.1%～2.8%(n=11)，方法的加标回收率为98.0%～103.5%。该方法准确、快速、简便、检测成本低，可用于萤石中总硫含量的测定。
Abstract：The method for determination of total sulfur in fluorite by iodimetry with high temperature combustion was established. Copper powder was mixed with fluorite sample as flux, by using oxygen as carrier gas, fluorite was heated and burned at 1 200℃ in a high-temperature combustion tube furnace. Sulfur in fluorite sample was converted into sulfur dioxide. Sulfur dioxide was absorbed by acidic potassium iodide-starch solution and titrated with potassium iodate standard titration solution. The optimal experimental conditions were as followed: the oxygen flow rate was 1.5 - 2.2 L/min, the sample quality was 500 mg, and the dosage of copper powder was 1 000 mg. Under the selected experimental conditions, the relative standard deviation of determination results was 2.1%-2.8%(n=11), and the recovery rate of the method was 98.0%-103.5%. The method is accurate, rapid, simple and low cost, which can be used to determining the total sulfur content in fluorite.
Keywords：fluorspar; sulfur; iodometry
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