电位滴定法测定铁中间合金中铁含量

Determination of iron content in intermediate ferroalloy by automatic potentiometric titration method

建立了铁中间合金中铁含量测定的自动电位滴定法,考察了溶样体系、还原剂类型及用量、滴定环境和共存离子干扰等因素的影响。结果表明,硝酸、过氧化氢和氢氟酸对测定结果有较大的影响,在滴定前应去除;磷酸会导致三氯化钛水解,影响测定结果,应避免引入;共存的Cr, Co和Cu等金属离子对测定结果没有影响。在1%~99%含量范围内,方法的相对标准偏差(RSD)为0.08%~0.26%。使用硅铁、锰铁和钕铁硼等有证标准样品验证了方法的准确度。该方法解决了可视滴定方法存在的滴定终点颜色干扰问题,减少了磷酸等试剂的用量,规避了分离干扰离子的复杂操作,简化了实验步骤,同时提高了铁含量测定的精密度。

The automatic potentiometric titration method was established for the determination of iron content in intermediate ferroalloys.The factors affecting the determination results of iron content,including sample dissolving system,the type and amount of reducing agent,the titration environment and the interference of coexisting ions,were studied.The results showed that nitric acid,hydrofluoric acid,and hydrogen peroxide had great influence on the determination results,which should be removed before titration.Phosphoric acid promoted the hydrolysis of titanium trichloride and affected the determination results.Coexisting metal ions such as Cr,Co and Cu did not affect the determination results.Within the content range of 1%~99%,the relative standard deviations(RSDs)of the method were 0.08%-0.26%,and the accuracy of the method was verified with certified reference materials such as ferrosilicon,ferromanganese and neodymium iron boron.This method solves the problem of color interference of titration end point in visual titration method,reduces the amount of hazardous chemicals such as phosphoric acid,avoids complex operations that interfering ion separation and improves the precision of iron content determination.