Abstract：Aluminum-manganese alloy was an element additive and deoxidizer used in steelmaking. The accurate determination of manganese content in it was helpful to better control the quality of its products. After the sample was dissolved with aqua regia, manganese(Ⅱ) was oxidized to manganese (Ⅲ) with perchloric acid in the medium of hot concentrated phosphoric acid. Then, manganese (Ⅲ) was titrated to manganese (Ⅱ) by ferrous ammonium sulfate standard solution with N-phenylanthranilic acid as the indicator. The endpoint was achieved when the color of solution changed from purple to bright yellow. Thus, a determination method of manganese in aluminum-manganese alloy was established by ferrous ammonium sulfate titration. In the medium of sodium diphosphate solution at pH 6.0-7.0, the sample solution was slowly titrated with potassium permanganate standard solution. With the help of a composite platinum electrode, the endpoint was achieved when there was a potential jump. Thererfore, a determination method of manganese in aluminum-manganese alloy was established by potassium permanganate potentiometric titration. The common impurities in aluminum-manganese alloy such as chromium, copper, iron, magnesium, titanium, nickel, boron and silicon had little influence on the determination results of two methods, which could be ignored. If there were vanadium and cerium, the correction deduction should be conducted in ferrous ammonium sulfate titration. The two proposed methods was applied in analysis of aluminium-manganese alloy samples. The relative standard deviations (RSD,n=11) of ferrous ammonium sulfate titration were between 0.36% and 0.50%, and the recoveries of standard addition were between 99.2% and 100.8%. The relative standard deviations (RSD, n=11) of potassium permanganate potentiometric titration were between 0.39% and 0.68%, and the recoveries of standard addition were between 99.2% and 100.7%. The proposed methods were applied in determination of AlMn20 alloy, and the standard method GB/T 20975.7-2020 was used for method verification. Both F test and t test showed that the two methods had good consistency with the standard method.
张金娥, 苏玉龙, 孙海峰, 李甜, 贺铭兰. 硫酸亚铁铵滴定法和高锰酸钾电位滴定法测定铝锰合金中锰[J]. 冶金分析, 2021, 41(9): 83-90.
ZHANG Jin’e, SU Yulong, SUN Haifeng, LI Tian, HE Minglan. Determination of manganese in aluminium-manganese alloy by ferrous ammonium sulfate titration and potassium permanganate potentiometric titration. , 2021, 41(9): 83-90.
