地质样品无污染高效分选锆石的技术和方法进展

锆石是应用最广泛的定年矿物,无污染地从地质样品中高效分选出锆石是获得代表地质样品准确信息的前提条件。传统锆石分选方法基于锆石的高密度和无磁性,主要通过机械破碎和不同水动力条件分选,存在破碎过程易污染和分选流程效率低的问题。针对这两个问题,本研究通过回顾和总结前人地质样品粉碎技术和高效矿物分选的方法,将高压脉冲电动力破碎技术、高温淬火和酸溶法结合,开发了一种能够实现锆石无污染、高回收的操作流程:高压脉冲电动力破碎→(淬火)→HF+HNO 3溶解→HCl+H 3BO 3溶解。本次研究以锆石含量较低的基性样品为对象进行了不同方法的对比,对于含有≥50μm锆石的地质样品,新方法的锆石回收率是传统方法的6倍以上;对于只含有<50μm锆石的地质样品,传统方法无法从几千克的样品中分选出锆石,而新方法可以从几十克样品中分选出几十颗锆石。拉曼光谱分析显示,酸溶数小时并不会显著影响中等结晶度锆石的结晶度,而高温淬火可以明显提高锆石的结晶度。离子探针分析表明,酸溶分选和淬火后酸溶分选的锆石,在测试精度范围内均没有明显Pb丢失。采用新分选方法,并结合离子探针U-Pb定年,本文首次报道了洛阳牡丹石和雅鲁藏布江中段玄武岩的年龄(分别为~1831Ma和~164Ma),以证明改进后的锆石分选方法实用有效。新锆石分选流程的推广将显著扩展锆石在基性岩研究中的应用空间。

Selective separation of copper and cadmium from zinc solutions by low current density electrolysis

Copper and cadmium ions were selectively separated from zinc sulphate aqueous solution or zinc ammonia/ammonium sulphate aqueous solution by low current density electrolysis.It was shown that the concentration of cadmium ion in zinc sulphate solution decreased from 4.56 g/L to 0.18 g/L in an electrolysis time of 8.5 h,whilst it decreased from 5.16 g/L to lower than 0.005 g/L in zinc ammonia/ammonium sulphate aqueous solution.On the other hand,the deposition rate of copper was so low that it was difficult to separate copper and cadmium ions from the zinc ammonia/ammonium sulphate aqueous solution during electrolysis.But copper ion could be decreased to 0.002 g/L in this solution through solvent extraction by using kerosene diluted LIX984N as extractant.Therefore,it is favorable to recover cadmium ion from the zinc ammonia/ammonium sulphate solution by electrolysis after solvent extraction of copper.