钼铁中Mo和Fe的联合测定

Combined Determination of Molybdenum and Iron in Ferro Molybdenum

研究了重铬酸钾滴定法测定钼铁中的Fe元素和偏钒酸铵滴定法测定钼铁中Mo元素的联合测定。采用硝酸溶样,硫酸冒烟,用氢氧化氨沉淀—氢氧化钠二次沉淀法达到Fe与Mo完全分离的目的。氢氧化铁用盐酸溶解,以钨酸钠为指示剂,用三氯化钛还原三价铁,过量的低价钛用重铬酸钾氧化,用二苯胺磺酸钠做指示剂,重铬酸钾溶液滴定。滤液在氟化铵存在下,用硫酸肼还原钼,以N-苯基邻氨基苯甲酸和二苯胺磺酸钠做指示剂,用偏钒酸铵标准滴定溶液滴定。本方法适用于钼铁中30%~50%Fe含量和50%~75%Mo含量的测定。测定结果的相对标准偏差≯0.06%(RSD,n=5),分析结果准确度高、精密度好,分析结果令人满意。

The combined determination of molybdenum and iron in ferro molybdenum by potassium dichromate titration and ammonium metavanadate titration was studied in this article.Complete separation of iron and molybdenum was achieved by precipitation with ammonia hydroxide and secondary precipitation with sodium hydroxide.Iron hydroxide was dissolved in hydrochloric acid.Sodium tungstate was used as indicator and ferric iron was reduced with titanium trichloride.Excessive low-valent titanium was oxidized with potassium dichromate.Iron content was determined by titration with sodium diphenylamine sulfonate as indicator and potassium dichromate solution as titrant.The filtrate was reduced with hydrazine sulfate in the presence of ammonium fluoride.Molybdenum content was determined by titration with n-phenylo-aminobenzoic acid and sodium diphenylamine sulfonate as indicators,ammonium metavanadate standard titration solution as titrant.This method was suitable for the determination of 30%-50%iron and 50%-75%molybdenum in ferro molybdenum.The relative standard deviation≯0.06%(RSD,n=5)of the results was satisfactory with high accuracy and precision.