Abstract：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.
