高氯酸脱水-重量法结合电感耦合等离子体原子发射光谱法测定富铌渣中二氧化硅

试样在750 ℃高温下被碳酸钠-过氧化钠熔融,用盐酸酸化,高氯酸冒烟使硅酸脱水生成二氧化硅胶体,过滤、洗涤后,将沉淀于950 ℃灼烧至恒重,在硫酸介质中用氢氟酸挥硅,再次灼烧恒重,差减两次恒重结果计算沉淀中二氧化硅量。应用电感耦合等离子体原子发射光谱法(ICP-AES)测定滤液中残留的二氧化硅量。将两部分数据加和可得富铌渣中二氧化硅总量。实验表明,恒重后的沉淀中有大量铌化合物存在,经挥硅处理其影响可忽略不计。方法用于富铌渣中二氧化硅量的测定,结果与ICP-AES一致,相对标准偏差(RSD,n=10)为0.48%,加标回收率在99%～100%之间。

Determination of silicon dioxide in niobium-enriched slag by perchloric acid dehydration-gravimetry combined with inductively coupled plasma atomic emission spectrometry

After the sample was fused by Na₂CO₃-NaOH at 750 ℃ and acidified by HCl, it was treated by perchloric acid smoking to make silicic acid dehydrate into silicon dioxide colloid. The obtained sample was filtered and washed, and the precipitate was then burned to reach constant weight at 950 ℃. After silicon in the precipitate was volatized by hydrofluoric acid in the medium of sulfuric acid, the precipitate was burned again to constant weight. The difference of the two weight results were the amount of silicon dioxide in the precipitate. While the silicon dioxide left in the filtrate was determined by inductively coupled plasma emission spectrometry (ICP-AES). The total amount of silicon dioxide in the niobium-enriched slag sample was thus obtained by adding the two results. It indicated that, after the precipitate reached constant weight, there was a large amount of niobium compound left which, however, its influence on the determination could be ignored by silicon volatilizing. The proposed method was applied to determination of silicon dioxide in niobium-enriched slag, the results were consistent with that by ICP-AES. The relative standard deviation (RSD,n=10) was 0.48%, and the standard addition recovery was 99%-100%.