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磷存在於铁矿及钢铁内为量极微,但影响质量极大。已往分析,时常用的有容量法和重量法;容量法用酸溶解试样,加入钼酸铵,将磷钼酸铵黄色沉淀,用一定量的氢氧化纳溶解,再以标准酸滴定。这方法较快,但正确度较差;尤其是少量磷的测定,误差较大。重量法一般是用镁合剂沉淀为磷酸铵镁,灼烧成焦磷酸镁。这方法正确度较高,但费时又长,不能配合各厂矿生产过程中的需要。
Phosphorus exists in iron ore and steel in very small quantities, but the quality of the great impact. In the past analysis, volumetric method and gravimetric method were often used. Volumetric method used acid to dissolve the sample, added ammonium molybdate, precipitated ammonium phosphomolybdate in yellow, dissolved in a certain amount of sodium hydroxide and titrated with standard acid. This method is faster, but the accuracy is poor; especially the determination of a small amount of phosphorus, the error is larger. Gravimetric method is generally precipitated with magnesium mixture of magnesium ammonium phosphate, burning into magnesium pyrophosphate. This method is more accurate, but time-consuming and long, can not meet the needs of the factories and mines in the production process.