EDTA络合滴定法测定柱状压块球化剂中金属镁

随机取柱状压块球化剂不少于20颗约500 g,用破碎机快速破碎分散后混合,取其中20 g试样,用乙酸(1+9)溶解试样中的金属镁及少量的铁,将大部分铁粉及其他不溶物过滤除去,移取一定体积的滤液,用氨水调节pH值至6~7,经铜试剂沉淀分离铁、铝等干扰离子,三乙醇胺掩蔽剩余干扰离子,以EGTA标准溶液预络合滴定钙,于盐酸羟胺、氨-氯化铵缓冲溶液(pH 10)中,以铬黑T为指示剂,建立了EDTA络合滴定法测定柱状压块球化剂中金属镁含量的方法。使用实验方法对柱状压块球化剂样品进行多次平行测定,相对标准偏差(RSD,n=6)小于2.0%。选取4个柱状压块球化剂样品按实验方法进行测定,并与标准方法JB/T4394-1999和差减法进行比较,测定结果基本一致。实验方法适用于测定金属镁质量分数在5%~15%范围内的柱状压块球化剂。

Determination of metallic magnesium in columnar briquetting nodularizer by EDTA complexometric titration

About 500 g (no less than 20 particles) of columnar briquetting nodularizer were randomly selected. After rapidly crushing, dispersing and mixing with the crusher, 20 g of sample was used for test. The metallic magnesium and little iron in sample were dissolved with acetic acid (1+9). After most iron powder and other insoluble substances were removed by filtration, the filtrate with certain volume was pipette and its pH value was adjusted to 6-7 with ammonia water. The interference ions such as iron and aluminum were separated by copper reagent precipitation method, and the residual interference ions were masked with triethanolamine. Meanwhile, calcium was pre-titrated with EGTA standard solution. Thus, a method for determination of metallic magnesium in columnar briquetting nodularizer was established by EDTA complexometric titration with chrome black T as indicator in hydroxylamine hydrochloride and ammonia ammonium chloride buffer solution buffer solution (pH 10). The proposed method was applied to the parallel determination of columnar compressed nodularizer samples. The relative standard deviation (RSD, n=6) was less than 2.0%. Four columnar briquetting nodularizer samples were determined by the experimental method. The results were consistent with thosed obtained by JB/T4394-1999 method and subtraction method. The proposed method was applicable for the determination of columnar briquetting nodularizer containing 5%-15% metallic magnesium.