超高纯石英纯化制备及机理研究

发布时间：2018-10-05 21:05

【摘要】：采用脉石英替代日益枯竭的水晶资源制备超高纯石英,替代昂贵的进口石英,满足国内市场需求,打破长期被美国垄断的被动局面具有重要意义。本文从四个方面对超高纯石英纯化制备及机理进行了深入的研究。采用XRD、ICP-MS、透／反射光两用显微镜、偏光显微镜、EPMA、LRM和显微微热台等分析方法,系统地分析了脉石英中固体、流体包裹体赋存状态及石英晶格中杂质元素的分布。该脉石英含有大量的包裹体,主要物相组成为钾长石、钠长石、云母、透辉石、铁铝榴石、钠闪石、黄铁矿、黄铜矿、赤铁矿及氯化钾晶体等。流体包裹体均为气液两相型,成分主要有H2O、CO2、CH4、烃类等。石英晶格中微量Al、Fe、Ti等元素类质同象替代Si,均匀分布于石晶体中,但边缘有所富集。采用EXCEL软件VBA语言代码,系统计算了硅酸盐、铝硅酸盐矿物在混合酸浸出体系中的分解反应化学平衡,构建了化学反应方程式、反应的始态、终态及反应平衡。分别计算出杂质矿物混合酸分解过程的热力学参数吉布斯自由能、平衡常数、ArGT(?)=A+BT等,并绘制组分分布图、Ellingham图。基于热力学方法建立了杂质矿物在混合酸浸出体系中分解排序规律与评价判据。杂质矿物分解反应△rGT(?)均0,且小于石英与HF、HCl分解反应ArGl(?),杂质矿物分解反应均能自发进行,且优先于石英分解,石英纯化在热力学上是可行的。分别研究了常压浸出、热压浸出、真空焙烧的最佳工艺参数与纯化效果。优化了真空焙烧-热压浸出联合纯化工艺,杂质元素Al、Fe、K、Na、Ca、Mg含量分别为：7.9、0.652、1.804、15、3.276、0.344 μg·g-1,制备出Si02含量为99.996wt%的超高纯石英。联合工艺纯化效果优于单一纯化工艺。通过构建高温Al-F-H2O系、FeS2-F-H2O系Eh-pH图,揭示了氟铝、氟硅和氟铁络合物稳定性区域及复杂的共存关系。与离子随着pH值增加逐渐转化为、、及。调控好反应体系Eh和pH,可有效控制浸出过程中杂质矿物分解反应条件。研究了真空焙烧对石英晶胞参数变化、晶型转变与石英纯化间的影响,揭示了Al、Fe、K, Na、Ca、Mg能谱面分布规律,元素特征X射线光子的面分布密度从大至小依次为：常压浸出热压浸出真空焙烧-热压浸出。研究表明常压混合酸分解纯矿物的反应均为一级反应,热压浸出,钠长石、黄铁矿分解反应属一级反应,钾长石、白云母分解反应为二级反应。基于杂质金属的多样性和复杂性采用差异化方法,按元素分类分别讨论了动力学理论模型并加以分析,具有重要的指导作用。常压浸出,Al、Fe、Na、Ca的去除符合不同控制过程的未反应缩核模型,而K的去除则符合Avrami模型,元素Al、Fe、K、Na、Ca、Mg纯化过程的表观活化能分别为：5.587、5.545、95.96、8.35、5.189和1.338 kJ·mol-1;热压浸出,Al、Fe、K、Na、Mg的去除均符合Avrami模型,而Ca的去除则符合内扩散控制未反应缩核模型,元素Al、Fe、K、Na、Ca, Mg纯化过程的表观活化能分别为：58.247、80.878、20.028、3.55、127.287和3.858 kJ·mol-1。
[Abstract]:It is of great significance to use vein quartz instead of crystal resource to prepare ultra-pure quartz, to replace expensive imported quartz, to meet the domestic market demand and to break the passive situation which has been monopolized by the United States for a long time. In this paper, the preparation and mechanism of ultrapure quartz were studied in four aspects. The solid, fluid inclusions and the distribution of impurity elements in quartz crystal lattice were systematically analyzed by means of XRD,ICP-MS, / reflectance microscope, polarizing light microscope, EPMA-LRM and microthermoscope. The quartz vein contains a large number of inclusions, and the main phases are potassium feldspar, albite, mica, diopside, ferric aluminite, sodium amphibole, pyrite, chalcopyrite, hematite and potassium chloride crystals. The fluid inclusions are of gas-liquid two-phase type, mainly composed of H _ 2O _ 2 CO _ 2H _ 4, hydrocarbons and so on. In quartz lattice, trace Al,Fe,Ti and other elemental isomorphism, instead of Si, are uniformly distributed in stone crystals, but the edges are enriched. The chemical equilibrium of decomposition reaction of silicate and aluminosilicate minerals in mixed acid leaching system was calculated by VBA language code of EXCEL software. The chemical reaction equation, initial state, final state and reaction equilibrium of the reaction were established. The thermodynamic parameters, Gibbs free energy and equilibrium constant ArGT (?) of the mixed acid decomposition process of impurity minerals were calculated respectively. BT et al. Based on the thermodynamic method, the law of decomposition, ordering and evaluation criteria of impurity minerals in mixed acid leaching system were established. RGT (?) 0, and less than ArGl (?) in the decomposition of quartz with HF,HCl. The decomposition of impurity minerals can be carried out spontaneously, and the decomposition of quartz is superior to that of quartz. The purification of quartz is feasible in thermodynamics. The optimum technological parameters and purification effects of atmospheric pressure leaching, hot pressure leaching and vacuum roasting were studied respectively. The combined purification process of vacuum roasting and hot pressure leaching was optimized. The content of impurity element Al,Fe,K,Na,Ca,Mg was 1: 7.9C 0.652U 1.804U 153.276N 0.344 渭 g g-1.The ultrahigh purity quartz with Si02 content of 99.996wt% was prepared. The purification effect of combined process is better than that of single purification process. By constructing the Eh-pH diagram of high temperature Al-F-H2O system FES _ 2-F _ H _ 2O system, the stable region and complex coexistence of fluoro aluminum, fluorosilicon and fluoroiron complexes are revealed. With the increase of the pH value, the ions and ions are gradually transformed into a. Controlling the reaction system Eh and pH, can effectively control the reaction conditions of the decomposition of impurity minerals during leaching. The effects of vacuum roasting on the crystal cell parameters, crystal transformation and quartz purification were studied, and the distribution of Al,Fe,K, Na,Ca,Mg energy spectrum surface was revealed. The surface distribution density of X-ray photons is in the order of atmospheric pressure leaching hot pressure leaching vacuum roasting and hot pressing leaching. The results show that the decomposition of pure minerals by mixed acid at atmospheric pressure is a first-order reaction. The decomposition of albite and pyrite is a first-order reaction and the decomposition of potassium feldspar and Muscovite is a second-order reaction. Based on the diversity and complexity of impurity metals, the dynamic theoretical models are discussed and analyzed according to the classification of elements, which plays an important guiding role. The removal of AlFeNa-Na ~ + Ca by atmospheric pressure leaching accords with the unreacted shrinking model of different controlled processes, while the removal of K conforms to the Avrami model. The apparent activation energy of the purification process of the element Al,Fe,K,Na,Ca,Mg is: 5. 58755.545N 95.968.35c5.189 and 1.338 kJ mol-1; respectively. The removal of AlFeK / Nahmg by hot pressure leaching accords with the Avrami model. However, the removal of Ca was in accordance with the model of internal diffusion control without reaction, and the apparent activation energy of the purification process of element Al,Fe,K,Na,Ca, Mg was: 58.247 (80.878) 20.028 (3.55127.287) and 3.858 kJ mol-1. (respectively).
【学位授予单位】：武汉理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TD97

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