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白云鄂博铁矿中氟的测定方法,国内普遍仍采用硝酸钍法和锆盐法来测定。由于这些方法存在着终点不易判断,与氟反应不是化学计量、放射性污染等弊病。我们通过试验证明,采用La—EDTA络合滴定法测氟,能满意地应用于铁矿中不同含量氟的测定。氟与镧反应是化学计量的,氟量1～60毫克之间、其镧/氟比值基本是一致的。欲使氟与镧生成的氟化镧沉淀完全,需保持溶液pH在1.5～3.5之间,可选用百里酚蓝或间甲酚紫、二甲基黄、对硝基酚、甲基橙等指示剂来指示。加热煮沸可促使沉淀凝聚。过量的硝酸镧于pH5.6～6.0醋酸钠缓冲溶液
Bayan Obo Iron Determination of fluorine in the country is still generally used thorium nitrate and zirconium salt method to determine. Because of these methods there is an end point difficult to judge, reaction with fluorine is not stoichiometry, radioactive contamination and other ills. We proved through experiments that using La-EDTA complexometric titration method can be satisfactorily applied to the determination of fluorine in iron ore with different contents. Fluorine and lanthanum reaction is stoichiometric, fluorine amount between 1 to 60 mg, the lanthanum / fluorine ratio is basically the same. To make the lanthanum fluoride and lanthanum formation of precipitation is complete, the need to maintain the solution pH between 1.5 to 3.5, the choice of thymol blue or m-Cresyl violet, dimethyl yellow, p-nitrophenol, methyl orange, etc. Indicator to indicate. Heating boil can promote precipitation agglomeration. Excess lanthanum nitrate in pH 5.6 ~ 6.0 sodium acetate buffer solution