About 500 g ( no less than 20 particles) of columnar briquetting nodularizer were randomly selected. Af-ter rapidly crushing, dispersing and mixing with the crusher, 20 g of sample was used for test. The metallic magne-sium 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 precip-itation 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 briquet-ting nodularizer was established by EDTA complexometric titration with chrome black T as indicator in hydroxyla-mine 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 devia-tion (RSD, n=6) was less than 2. 0%. Four columnar briquetting nodularizer samples were determined by the ex-perimental 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.%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。
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