石英氧化浸出提纯中的络合离子的作用及机理

Effect and Complexation Mechanism of Complex Ion in Quartz Purification by Oxidation Leaching

针对采用氢氟酸和草酸氧化浸出制备高纯石英的工艺,以元素Fe的去除为例,着重介绍了石英氧化浸出提纯过程中草酸络合离子的作用及其络合机理。草酸酸性强,络合常数大,在金属离子从石英表面氧化浸出过程中,C2O24-与Fe螯合,形成稳定的络合物,经洗涤分离脱除。研究建立了其各级络合物分布图,为精确控制化学反应提供了理论依据。另外还测定了不同处理方式对石英表面ζ电位的影响。研究结果表明:采用HF和草酸联合浸出工艺可将石英中杂质金属元素含量从40～50 ppm降至20～25 ppm,其中元素Fe从2 ppm降至0.186 ppm。

For the preparing process of high - purity quartzite by the oxidation leaching with hydrofluoric acid and oxalic acid, the effect and complexation mechanism of oxalic acid complexes in iron removal during complexation reaction were studied. As oxalic acid with strong acidity has high complex constant, the C2O4^2- chelates with Fe ions to form stable complexes in oxida- tion leaching of metal ion from the surface of quartzite particulate, and then the metal ions can be removed from the quartz surface by washing. The research established distribution charts of the complexes to provide theoretical basis for precisely controlling the chemical reactions. The influence of different treatments to ζ potential of quartz surface was also tested. The researched results showed that by leaching with hydrofluoric acid and oxalic acid the total content of metallic elements as impurities could be reduced from 40 ~ 50 ppm to 20 - 25 ppm, while Fe element could drop from 2 ppm to 0. 186 ppm.