Determination of silicon dioxide in lead-zinc ore by potassium fluosilicate titration with acid dissolution
WANG Na1, TENG Xin-hua*1, WANG Li-qiang1, CHEN Xi2, LIU Yi-bo1, WU Lei1
1. Tianjin Center of Geological Survey,China Geological Survey,Tianjin 300170,China; 2. Tianjin Geological and Mineral Testing Center,Tianjin 300191,China
Abstract：A determination method of silicon dioxide in lead-zinc ore samples was proposed by potassium fluosilicate titration after decomposition with acid. The lead-zinc ore sample was digested with nitric acid and hydrochloric acid successively. Then, the hydrofluoric acid was added to react with silicon dioxide to form fluosilicic acid, which reacted with excessive potassium nitrate in nitric acid medium to form potassium fluosilicate precipitate. After filtration and washing, the precipitate was dissolved in boiling water. With nitrazine yellow as indictor, the hydrofluoric acid generated by hydrolysis was titrated by sodium hydroxide standard solution to indirectly determine the content of silicon dioxide in lead-zinc ore. The results showed that the interference of much lead in lead-zinc ore could be effectively eliminated when the precipitate was filtrated and washed with 50 g/L potassium nitrate-50% ethanol solution after placing for 20 min with 10 mL of nitric acid as precipitation medium and 3.0 g of potassium nitrate as precipitator. The color mutation at titration endpoint was more obvious when nitrazine yellow was selected as the indicator. The proposed method was applied to the determination of silicon dioxide in lead-zinc ore certified reference materials, and the results were consistent with the certified values. The proposed method was also used in the determination of lead-zinc ore actual sample. The relative standard deviation(RSD, n=12) was 0.5% and 1.3%, respectively. The test was also compared with the conventional gravimetric method, and the results were consistent. The proposed method was applicable for the determination of the mass fraction of silicon dioxide in range of 8%-67% in lead-zinc ore.
王娜,滕新华,王力强,陈曦,刘义博,吴磊. 酸溶-氟硅酸钾滴定法测定铅锌矿中二氧化硅[J]. 冶金分析, 2015, 35(6): 65-69.
WANG Na, TENG Xin-hua, WANG Li-qiang, CHEN Xi, LIU Yi-bo, WU Lei. Determination of silicon dioxide in lead-zinc ore by potassium fluosilicate titration with acid dissolution. , 2015, 35(6): 65-69.
