铁的测定一般采用二氯化锡将铁(Ⅲ)还原至铁(Ⅱ),然后加入二氯化汞以氧化过量的二氯化锡,用二苯磺酸钠为指示剂,以重铬酸钾标准溶液滴定。该法准确度高,易掌握。但汞盐有毒,对环境保护和人身健康均有影响。本文用甲基橙代替二氯化汞。二氯化锡还原的酸度以4—6mol/L盐酸介质为宜;如矿石中含钛,可在还原前加入硫酸和磷酸。上述方法消除了汞污染,又可避免还原剂过量太多使铁的测定结果偏高。分析步骤称取0.1000—0.2000克试样,置于300毫升烧杯中,加入15—20毫升氯酸钾饱和的硝酸(若含硅较高的矿样,由于产生大量絮状硅酸吸附和包裹铁(Ⅲ)离子,使之不易完全被二氯化锡还原导 The determination of iron generally uses tin dichloride to reduce iron (III) to iron (II), then add mercury mercuric chloride to oxidize excess tin dichloride, with sodium diphenylsulfonate as an indicator, dichromate Titration of potassium standard solution. The accuracy of the law, easy to grasp. However, mercury salts are toxic and have an impact on environmental protection and personal health. In this paper, methyl orange instead of mercuric chloride. Tin dichloride reduction of acidity to 4-6mol / L hydrochloric acid medium is appropriate; such as titanium in the ore can be added before the reduction of sulfuric acid and phosphoric acid. The above method eliminates the mercury pollution, but also can avoid the excess of the reducing agent to make the determination result of the iron high. Analysis step Weigh 0.1000-0.2000 grams of sample, placed in a 300 ml beaker, add 15-20 ml of potassium chlorate saturated nitric acid (if the higher silicon content of the sample, due to the production of a large number of flocculent silicic acid adsorption and iron (Ⅲ ) Ions, so that it is not easy to be completely reduced by tin dichloride