石英中金属元素迁移扩散及其机理研究

发布时间：2018-10-24 13:42

【摘要】：近年来,电子工业和光伏产业发展迅速,对高纯石英的需求量不断增大。而一、二级优质水晶资源日益枯竭,探索用普通石英代替水晶制备高纯石英的技术具有战略意义和应用价值。对中国西南某地精制石英砂,分别在真空与氮气气氛下焙烧,研究不同焙烧温度下石英相变热中杂质金属元素迁移扩散的规律,对于揭示高纯石英纯化机理是一种新的尝试。采用XRD、ICP、光学显微镜以及电子探针分析进行矿物学研究,旨在查明金属元素在石英中的赋存状态及化学含量。在石英相变热作用下,利用不同气氛作为保护气体并诱导杂质金属元素向石英表面迁移扩散,从而达到纯化的目的。采用ICP、XRD、SEM、XPS等测试分析技术对试验结果进行了分析讨论,得到以下结论:1.工艺矿物学研究结果表明:试验所用石英SiO2含量高达99.968%,主要杂质金属元素为Na、K、Fe、Al、Ca等,占杂质元素总含量的87.14%。杂质元素主要富集在微米级矿物包裹体和流体包裹体中,其中主要杂质矿物包裹体有云母类、长石类、透辉石等铝硅酸盐矿物和含铁、钛的金属矿物,此外还有少量表面浸染铁。2.焙烧试验结果表明:采用焙烧去除石英中的Na、K、Fe元素杂质效果良好,而去除Al、Ca元素的效果一般。⑴在真空条件下,焙烧温度为1500℃,焙烧3h时,石英样品中的Na元素含量从50.91μg g-1降至15.14μg g-1,去除率达72.22%。⑵在氮气气氛下,焙烧温度为1500℃,焙烧3h时,石英样品中的K元素含量从23.43μg g-1降低至5.73μg g-1,去除率为75.54%。⑶在氮气气氛下,焙烧温度为1500℃时,焙烧3h,Fe元素的去除效果最好,石英样品的铁元素含量从17.78μg g-1降至2.45μg g-1,去除率达86.22%。⑷优化的工艺条件:在氮气气氛下,焙烧温度1500℃,焙烧4h,石英中的总金属杂质含量从179.65μg g-1降至108.68μg g-1,作业去除率达39.50%。这是因为在相同试验条件下,金属元素的物理、化学特性不同,迁移扩散的效果表现出较大的差异性。3.焙烧温度为1500℃时气氛对石英相变的影响明显。理论上1447℃时石英开始转变为方石英,方石英化过程中石英晶胞参数必然发生改变。XRD的分析结果表明,在氮气气氛中方石英的转化率明显高于在真空条件中的转化率。晶胞参数的计算结果表明,600℃~900℃焙烧区间,温度和气氛对晶胞参数的影响甚微,1500℃时,温度和气氛对晶胞参数的影响明显。说明1500℃时石英晶体获得足够的热能促使石英向方石英晶型转换,此时石英晶格中原子也会发生定向重排。气氛的诱导和热能的双重作用导致填隙原子(K、Na、Li即Al原子的配位原子)或取代Si原子的Al原子向表面发生迁移。4.XPS分析结果表明,在氮气气氛下,1500℃焙烧4个小时后,石英样品表面的K、Na、Al、Ca等金属杂质元素含量明显降低。说明1500℃时,杂质金属元素在气氛的诱导和热能的双重作用下向石英表面发生迁移并扩散,石英得到了纯化。
[Abstract]:In recent years, with the rapid development of electronics industry and photovoltaic industry, the demand for high purity quartz is increasing. First, the secondary high quality crystal resources are exhausted day by day, so it is of strategic significance and application value to explore the technology of preparing high purity quartz with ordinary quartz instead of crystal. This paper deals with the migration and diffusion of impurity metal elements in quartz phase change heat at different calcination temperature by calcining quartz sand in vacuum and nitrogen atmosphere in southwest China. It is a new attempt to reveal the purification mechanism of high purity quartz. The mineralogical study was carried out by means of XRD,ICP, optical microscope and electron probe analysis in order to find out the occurrence state and chemical content of metallic elements in quartz. Under the thermal action of quartz phase transformation, different atmospheres are used as protective gases and impurity metal elements are induced to migrate to the surface of quartz, so as to achieve the purpose of purification. The test results are analyzed and discussed by ICP,XRD,SEM,XPS and other testing techniques, and the following conclusions are obtained: 1. The results of technological mineralogy show that the content of SiO2 in quartz is as high as 99.968. The main impurity metal element is Na,K,Fe,Al,Ca, which accounts for 87.14% of the total content of impurity elements. The impurity elements are mainly enriched in micron mineral inclusions and fluid inclusions, among which the main impurity mineral inclusions are mica, feldspar, diopside and other aluminosilicate minerals, as well as iron and titanium containing metallic minerals. In addition, a small amount of surface impregnated iron. 2. The results of roasting test show that the removal effect of Na,K,Fe element in quartz by roasting is good, but the removal effect of Al,Ca element is general. 1 under vacuum condition, the calcination temperature is 1500 鈩，

本文编号：2291571