高钼白钨矿硫磷混酸协同浸出液中钨钼酸化络合微观差异及其质子化耦合的自组装机制研究

The mixture of sulfuric- and phosphoric-acid synergistically leaching technology, with a series of advantages such as less pollution, high leaching rate and low cost, has been a new technology to leach the low grade scheelite with high molybdenum content. However, the W(VI)/Mo(VI) exists in the form of isopoly and heteropoly ions in the following leachate. The lack of details of their existence form, microstructure and distribution rule gives rise to no theoretical ground for developing the new craft of their efficient separation in the subsequent metallurgical extractive process, which has seriously restricted the application of mineral leaching new technology. Therefore, this proposal will be carried out as follows: 1) By the measurement and analysis of spectroscopy characterization technology as well as the structure chemistry calculation, we will investigate the influences of different macro-conditions on the dominant component, configuration of tungstic/molybdic isopoly acid (IPA) and heteropoly acid (HPA) ions, as well as the main interaction type between W(VI)-IPA/HPA ions and Mo(VI)-IPA/HPA ions in the complex mixture solutions of sulfuric- and phosphoric-acid; 2) Focusing on the dynamic process of mononuclear tungstate/molybdate ions gradually forming the multinuclear IPA/HPA ions, we will investigate the competitive migration behavior of proton and the distribution of protonated active sites of precursor in the aggregation process. And then, the possible self-assembly pathways, which depends on the proton behavior and distribution of protonated active sites, will be analyzed. The key factors and aggregation nodes of disturbing the formation trend of W(VI)/Mo(VI)-IPA/HPA ions with different components and configurations will be discussed. Based on the research results of 1) and 2), the evolution of micro-structure of W(VI)/Mo(VI)- IPA/HPA ions as a function of acidity, salinity and temperature will be illuminated. Finally, we will give an explicit picture of speciation and structure of W(VI)/Mo(VI) under the dynamic leaching conditions, and then extract the difference of each other's microstructure and property, as well as its corresponding macro-condition windows. The results of this proposal can be provided as a theoretical support to develop new craft for the tungsten-molybdenum separation in the relevant systems.

硫磷混酸协同浸矿技术因具有污染小、浸出率高和成本低等诸多优点，已成为处理难冶高钼白钨矿的新技术，但浸出液中钨钼以同多酸或杂多酸离子等物种形式存在，因其微观结构及物种分布规律信息的缺失，给后续高效分离新工艺的提出造成理论失据，已严重限制了该浸矿技术的应用。为此拟开展以下研究工作：1）对硫磷混酸复杂溶液进行谱学测量解析和量化理论计算，探究不同宏观条件对钨钼多酸离子优势组成构型和主要离子间相互作用类型的影响；2）考察单核钨钼酸根离子逐步形成多核多酸离子的动态过程，研究聚合进程中质子竞争迁移行为、前驱体质子活性位分布，分析与之耦合的可能自组装反应路径，探讨影响多酸离子走向不同组成、构型的关键因素及聚合节点。结合1）和2）的结果，揭示钨钼多酸离子微观结构随宏观条件变化的动态演变规律，构建钨钼在动态浸出液中的微观精细谱图，发现两者微观性质的差异及对应的宏观条件窗口，为钨钼分离新技术的开发提供理论支撑。

针对硫磷混酸协同浸出钨矿后续料液中相似元素钨钼处于高酸、浓硫磷和多组元复杂溶液环境难以分离的特点，本项目由料液中钨钼本身自组装特性出发，从钨钼多酸离子簇的溶液化学入手，展开钨钼物种形态和自组装机制研究，建立了可用于原位表征典型硫磷混酸含钨钼溶液中多酸离子簇的多谱学定量分析方法，实现了热力学摄动积分耦合质子为“虚原子”第一性原理分子动力学模拟方法在多酸离子簇自组装前驱体质子行为捕捉与其活性位点分布确定的应用。采用上述方法进行了硫磷混酸含钨钼溶液的结构表征、钨钼多酸离子簇自组装机理及潜在钨钼分离方法研究，并提出钨钼分离新工艺开发的方向。结果表明：含钼酸性富磷溶液中钼物种的形态几乎不受磷含量和陈化时间影响，但受酸度影响显著。在低酸度溶液中，钼主要以P2Mo5O236−和Mo8O264−形式存在。随着酸度增加，钼多酸离子簇会解聚，主要以钼氧阳离子MoO22+或其二聚形式存在，磷不参与到钼物种的形成过程中。相反，含钨系列溶液中钨物种受三个因素影响都显著，特别是酸度和陈化时间。在低酸性溶液中，钨以P2W5O236−和NaPW11O396‒的形式存在，陈化时间和高酸度都会促进二者转化为钨的Keggin离子。随着酸度增加，Keggin离子未解聚反而会逐步聚集，其粒径最高可达~100Å，团聚体含量会随着溶液酸度及陈化时间的增加而增加，最终会析出磷钨杂多酸晶体。这些结果展示了溶液中钼聚阴离子解聚和钨Keggin离子稳定聚合的新性质差异。同时，明确了质子活性位点分布的确认在钨钼二聚离子簇聚合路径设计中的关键作用，发现钨钼多酸离子簇前驱体的质子活性位一直是端位氧而非羟基，由此纠正了人们长久以来对钼酰阳离子的认知偏差：其真实形式为Mo(OH)4(H2O)22+，而非MoO2(H2O)42+。本项目研究结果为硫磷混酸料液中分离钨钼系列理论研究的展开奠定了良好的基础，并为新浸矿工艺的实施提供了理论支撑。