EDTA络合滴定法测定柱状压块球化剂中金属镁

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

随机取柱状压块球化剂不少于20颗约500g,用破碎机快速破碎分散后混合,取其中20g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。

About 500g（no less than 20particles）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 6-7with 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.