关于高纯石英原料矿石地质学评价方法的探讨

高纯石英资源是一种重要的战略性资源。本文结合高纯石英成矿地质特征及其对后期选矿提纯、材料加工等的影响,系统总结了高纯石英原料中杂质的赋存状态、形成机理以及评价方法等,得出：(1)可以作为高纯石英原料的潜在岩石类型有花岗伟晶岩(包括不含暗色矿物的伟晶状花岗岩)、脉石英以及水晶,岩浆演化晚期的伟晶状花岗岩-伟晶岩早期阶段的NYF型花岗伟晶岩结晶形成的石英纯度更高,后期适当的变形变质作用更有利于高纯石英矿床的形成。高纯石英原料矿石中石英矿物呈现无色透明至半透明,矿物构造裂隙少,伟晶岩型矿石矿物组成通常为石英、钠长石、条纹长石、白云母等,黑云母等暗色矿物含量极少,基本不见锂辉石、独居石等稀有金属矿物和电气石、萤石等含挥发分矿物。(2)影响高纯石英的主要地质因素包括脉石矿物及晶界杂质、包裹体、晶格杂质等。其中包裹体类型、数量和尺寸是包裹体评价的关键指标,天然石英矿物中的气液两相包裹体、矿物包裹体和<10μm包裹体应尽量少;Al和Ti是晶格杂质元素评价标志性元素,通常要求天然石英矿物中Al<50×10^-6和Ti<10×10^-6。(3)建...     

鄂东南付家山脉石英矿杂质特征及其用作高纯石英原料的潜力

作为战略性矿产资源之一,高纯石英已广泛应用于集成电路、半导体芯片、太阳能等高新技术产业中,但是能够生产高纯石英的原料矿床极为稀缺,我国尤为紧缺高纯石英原料矿。鄂东南地区是湖北省脉石英矿床的主要分布区。本文针对鄂东南付家山脉石英矿床,通过光学显微镜、扫描电子显微镜观察了脉石英的脉石矿物类型和包裹体特征,采用电感耦合等离子发射光谱法(ICP-OES)对原矿进行了微量元素分析,旨在获得付家山脉石英矿床的杂质元素特征,进而评价矿床用作高纯石英原料的潜力。结果表明,付家山脉石英矿石SiO₂含量大于99.95%,杂质元素主要为Al、K、Fe、Ti、Ca等,脉石矿物主要有白云母、钾长石、铁氧化物等,流体包裹体较为发育。杂质元素分析结果表明,付家山脉石英原矿质量达到低端高纯石英标准,经传统工艺提纯后,可能具有生产中高端高纯石英的潜力。     

高纯石英原料特征和矿床成因研究现状综述

高纯石英具有重要的战略地位,是高新技术产业的基础原材料。本文对高纯石英原料的特征和矿床成因研究方法进行了系统的归纳。通过观察石英岩相学特征,分析矿物包裹体及流体包裹体的数量、大小、化学成分、存在形式和分布状态,以及SiO2和微量杂质元素的含量和赋存状态,可以研究高纯石英原料的矿物学特征;通过Ar Ar同位素定年可以计算高纯石英原料矿床的成矿年龄;通过H—O同位素测试,Ti、Al、Ge、Li等微量元素含量分析,可以研究高纯石英原料矿床的成矿物质来源;通过分析流体包裹体的均一温度、盐度、化学组成等特征以及SEM CL微结构观察,可以研究高纯石英原料矿床的成矿作用过程。在此基础上,本论文对我国高纯石英行业的发展提出相关的建议。     

高纯石英原料特征和矿床成因研究现状综述

高纯石英具有重要的战略地位,是高新技术产业的基础原材料。本文对高纯石英原料的特征和矿床成因研究方法进行了系统的归纳。通过观察石英岩相学特征,分析矿物包裹体及流体包裹体的数量、大小、化学成分、存在形式和分布状态,以及SiO2和微量杂质元素的含量和赋存状态,可以研究高纯石英原料的矿物学特征;通过Ar Ar同位素定年可以计算高纯石英原料矿床的成矿年龄;通过H—O同位素测试,Ti、Al、Ge、Li等微量元素含量分析,可以研究高纯石英原料矿床的成矿物质来源;通过分析流体包裹体的均一温度、盐度、化学组成等特征以及SEM CL微结构观察,可以研究高纯石英原料矿床的成矿作用过程。在此基础上,本论文对我国高纯石英行业的发展提出相关的建议。     

高纯石英的研究进展及发展趋势

石英是一种在地壳上大量分布,有着广泛工业用途和广阔应用前景的矿物。当石英晶体形成演化时,受结晶时环境条件、流体性质、结晶后遭受改造(如变质作用、构造变形和热扰动等)等影响,杂质元素如P、Ti、Ge、Al、B、Be、Ca、Na、K、H、Li等会或多或少存在于石英晶体中,因此在自然界不存在纯SiO₂组分的石英。同时,基于石英的微量元素组成,可以反演石英源区和形成演化过程,并用于研究岩石及矿床成因等科学问题。石英晶体内部杂质元素以类质同象替代、气液包裹体、矿物包裹体(不能按尺度分,应该按照状态划分存在形式)3种形式存在。石英中杂质元素的种类、含量、赋存形式,特别是包裹体特征将直接影响石英资源的品质和工业用途。本文还系统地阐述了石英的发光特性、工艺性能以及高纯石英的质量分类与标准和高纯石英原料来源等方面的内容。在本研究中,通过光学显微镜和激光拉曼测试,初步地查明了苏北张锦庄石英砂和广西姑婆山花岗岩石英中流体包裹体的分布和矿物包裹体的种类,这是开展后续研究的基础。高纯石英是优质石英资源经纯化加工得到的高品质石英原材料,可用于石英玻璃、石英坩埚、半导体、高温灯管、光纤、精密光学、微电子和太阳能等高新技术产业中。研究高纯石英原料的评价体系、理想源岩和形成机制有益于持续性地供给高纯石英原料, 极大地提高了石英原料的工业附加值。     

高纯石英矿物资源工程研究

高纯石英是世界稀缺和我国短缺的高技术战略矿物资源,是石英晶格Al杂质的质量分数≤30×10-6的天然矿物,晶格Al及其他粒内杂质元素有均匀、非均匀,环带三种分布形式,其含量和分布形式是决定产品纯度及提纯工艺限度的根本因素。无同期伴生金属矿化是高纯石英矿床成矿的必要条件,预测和寻找大型高纯石英矿床可类比美国伟晶白岗岩型矿床。高纯石英矿物工程前沿技术是除高杂石英、除粒内杂质及粉碎整形。国家主导大型高品质高纯石英矿床预测找矿是发展我国高纯石英产业的关键。     

微波在高纯石英提纯实验中的应用

随着水晶资源的日益枯竭,利用脉石英制备高纯石英以代替水晶已经成为一项需要迫切解决的技术问题。高纯石英中,铁杂质是最主要同时也是对产品质量影响最大的有害杂质之一,如何有效地除去脉石英中的铁杂质一直就是高纯石英生产中的难点和重点。当前主要是用酸浸的方法降低铁杂质的含量,主要存在的问题是处理时间较长,同时铁杂质含量也不容易降得更低。通过对微波在高纯石英提纯实验中应用的研究,表明微波可以有效地“打开”石英矿物中含铁的包裹体,不仅能促进含铁杂质矿物的酸浸去除,还可以极大地加快酸浸的速度,促进高纯石英的生产,同时为微波技术在高纯石英生产中的应用奠定了坚实的基础。     

石英中有害杂质元素分布特征和赋存状态及提纯方法

对石英原料的加工分选提纯,是获得高纯石英原料的主要途径,而有关对石英晶体中有害杂质的分选提纯,国内对这方面的工作较少。根据水晶、石英的ICP分析结果,对水晶石英晶体中的有害杂质元素主要种类、分布特征、在晶体中的赋存状态及提纯方法,分别进行了讨论。     

白云鄂博超大型稀土-铌-铁矿床成矿过程中的流体不混溶作用

白云鄂博超大型REE-Nb-Fe矿床赋存在白云岩内，矿体由磁铁矿、稀土氟碳酸盐、萤石、霓石、角闪石、方解石和重晶石等矿物组成。在白云鄂博矿床矿石和脉石矿物中赋存有两/三相富CO₂、三相高盐卤水和两相水溶液包裹体3大类型。显微测温表明富CO₂包裹体内还有近于纯的CO₂，成矿流体为H₂O-CO₂-NaCl-（F-REE）体系。高盐卤水包裹体和富CO₂包裹体共生且具有近似的完全均一温度，表明初始热液发生了流体不混溶作用。流体包裹体中出现稀土子矿物，表明初始成矿流体含有很高的稀土元素，这也许是形成白云鄂博超大型稀土矿床的原因。     

阜山金矿床东风矿段脉石英的红外光谱找矿标型

石英是原生金银矿物的主要载体矿物。利用红外光谱方法测定了东风矿段３６ 件脉石英包裹体样品的 Ｈ２ Ｏ、 Ｏ Ｈ 和 Ｃ Ｏ２ 的相对吸光度。结合对应样品的相对含量与吸光度的相关分析, 其结果为深部矿体定位预测提供了参考, 并给出了东风矿段脉石英的红外光谱找矿标型。     

Mechanisms of isomorphic substitution in quartz

Mechanisms of the incorporation of isomorphic impurities of Al, Ti, and Ge into quartz were studied by EPR techniques. For this purpose, laboratory experiments were carried out on quartz annealing, which allowed us to model the processes of impurity atom introduction into the quartz lattice. The investigation of the kinetics of these processes showed that they are described by diffusion-controlled reactions. In many samples, a proportional relationship was observed between the concentrations of Al and Ti impurities incorporated into the quartz structure during laboratory annealing. A comparison of the experimental results with the character of the natural distribution of isomorphic impurities in quartz revealed their similarity. Based on the analysis of the results of our investigations, two main mechanisms were proposed for isomorphic substitutions in quartz. One of them is referred to as the capture mechanism and corresponds to the incorporation of isomorphic impurities during mineral formation. The second, diffusion mechanism operates after the crystallization of quartz. The isomorphic impurities incorporated into the quartz structure by this mechanism are either formed through the decomposition and transformation of composite complexes or as a result of diffusion from crystalline and gas-liquid inclusions. It was suggested that both mechanisms are responsible for the incorporation of Al and Ge impurities into the mineral lattice, whereas Ti is introduced mainly by the diffusion mechanism. The accounting for the mechanisms of isomorphic substitutions provides a means to significantly increase the reliability of the interpretation of genetic information recorded in the distribution of structural impurities in quartz. Original Russian Text ? L.T. Rakov, 2006, published in Geokhimiya, 2006, No. 10, pp. 1085–1096.     

Impurity Elements in Quartz from Gold Deposits of the Darasun Ore Field (Eastern Transbaikalia,Russia): Electron Paramagnetic Resonance Data

The distribution of substitutional Al, Ti, and Ge impurities in quartz samples from the Darasun, Teremkinskoe, and Talatui gold deposits, located in the Darasun ore field, were studied by electron paramagnetic resonance. The relationship between the isomorphous substitution and dynamic recrystallization of quartz was studied by optical and scanning electron microscopy. It was found that analysis of the plots of interdependence between the concentrations of various substitutional impurities in quartz (isogens) can detect development trends of isomorphous substitution. Two isomorphous substitution stages were recognized, one associated with quartz crystallization, and the other, with its subsequent dynamic recrystallization. The first stage is characterized by incorporation of Al impurity into the quartz crystal lattice, and the second, by incorporation Ti impurity. A Ge impurity is a catalyst for isomorphous substitution, and its concentrations vary widely. It is noted that the second stage plays a decisive role, because it accounts for the incorporation of the larger part of substitutional impurities. This process is facilitated by the dynamic recrystallization of quartz. Four genetic quartz groups, described by individual isogens, have been recognized in the Darasun ore field. Two of them correspond to quartz crystallized directly from a magmatogenic fluid or redeposited with the melt’s participation, and the other two groups, to quartz crystallized from an altered fluid. It was found that substitutional Al concentrations are retained in quartz after redeposition, whereas substitutional Ti concentrations decrease dramatically Mineral formation processes at each gold deposit are reviewed. Two types of temperature zoning, normal and reverse, have been recognized at the Darasun deposit. Each is characterized by an individual genetic quartz group and the degree of closedness of the mineral formation system. The genetically similar magmatogenic quartz samples found at the Darasun and Talatui deposits indicate the uniformity of the mineralization process in the Darasun ore field. The established trends of isomorphous substitution in quartz are useful in studies of the ore formation histories of gold and other ore deposits.

     

载金石英的化学成分特征及其意义

利用电子显微镜(EM)及能谱仪(EDS),分析研究了变生热液形成的载金石英的化学成分、离子扩散作用以及金在石英中的赋存状态等问题,探讨了它们的形成和变化机理。研究结果表明:Al~(3+)、Ti~(3+)、TFe、Na~(+)、K~(+)、Ca~(2+)等在石英中为类质同像混入物;石英和黄铁矿之间的离子相互扩散作用,表现为石英中Al离子的带出和Fe离子的带入,黄铁矿中Fe离子的带出和Al离子的带入;石英中呈分散状态分布的金主要为离子金,它们充填在石英结构中,起平衡电价的作用。     

流体包裹体及石英LA-ICP-MS分析方法的建立及其在矿床学中的应用

流体包裹体LA-ICP-MS(激光剥蚀-电感耦合等离子体质谱仪)分析具有高精度、低检测限、多元素同时微区原位检测的特点,因此在精细刻画成矿过程、深入揭示成矿机理方面具有传统方法无可比拟的优势。通过人工合成石英Na Cl-H2O-Rb-Cs和Na Cl-KCl-Ca Cl2-H2O-Rb-Cs流体包裹体,使用NIST610为外标、显微测温Na Cl等效盐度(电价平衡方法)为内标,建立了流体包裹体L A-ICP-MS分析方法。分析结果的相对误差在±16%以内,绝大部分在±10%以内,相对标准偏差(RSD)小于7%。同时结合国际上推荐的石英标样,使用NIST610为外标、无内标法,建立了石英微量元素LA-ICP-MS分析方法。分析结果表明,石英中主要元素Li、Al和Ti的相对误差在±10%以内,相对标准偏差小于5%。利用建立的方法对鲁西早白垩世王家庄Cu-Mo矿开展了应用研究,结果显示该矿富气相包裹体更富Cu,而含子矿物包裹体富Mo,暗示Cu和Mo可能具有不同的搬运机制,Cu更倾向于气相,Mo则倾向于进入液相,结合流体沸腾现象的存在,这可能是导致该矿上铜下钼分带沉淀的重要因素。此外,从早期岩浆成因石英到成矿期热液石英以及成矿期后石英,微量元素具有明显的Ti降低而Al升高的趋势,暗示成矿元素Cu、Mo的沉淀可能同时还受到温度和流体酸碱度变化的控制。     

Minor elements in quartz from hydrothermal-metamorphic veins in the Nether Polar Ural Province

Vein quartz from the Nether Polar Ural Province was examined by atomic emission spectrometry, gas chromatography, electron paramagnetic resonance, and electron microscopy. According to atomic emission spectrometric analysis, the total concentration of Al, Fe, Mg, Ti, Ca, Na, K, and other minor elements in the quartz varies from 8 to 47 ppm. The lowest concentrations of minor elements were detected in the granulated quartz. Giant-crystalline milk-white quartz is noted for higher concentrations of minor elements, including Na, K, and Ca, because it contains gas-liquid inclusions. The fine-grained quartz contains very small mineral inclusions and is thus noted for elevated concentrations of Ca, Fe, K, Mg, and Ti. Gas chromatographic data on the gas phase separated from the quartz at its heating indicate that this phase contains H₂O, CO₂, and other components. The H₂O concentration reaches 429 ??g/g, while the CO₂ content is commonly no higher than 20 ??g/g. Gas separation is at a maximum at temperatures of 100?C600°C, when gasliquid inclusions decrepitate, as is typical, first of all, of the giant-crystalline milk-white quartz. Gas separation continues at higher temperatures (below 1000°C) but is much less intense. The electron microscopic examination of quartz grains after their acid treatment indicates that the surface of these grains is covered by caverns of various morphology and size, which were produced by the partial dissolution of the quartz and the opening of its gas-liquid and mineral inclusions occurring near the surface; the inclusions were not, however, completely removed. The crystal structure of the quartz contains minor Al, Ge, Na, Li, Ti, and Fe. The lowest concentrations of Al and Ge paramagnetic centers are typical of the granulated (recrystallized) and fine-grained quartz. The giant-crystalline quartz, including its transparent varieties, and individual quartz crystals, first of all their smoky-citrine varieties, contain higher concentrations of minor elements. In the Nether Polar Ural Province, granulated quartz is potentially promising for producing especially pure quartz concentrates. The quality of the translucent coarse-to giant-crystalline quartz, which predominates in the resources and reserves, is deteriorated by gas-liquid inclusions in it and requires deep processing of the raw minerals.     

Cathodoluminescence imaging and titanium thermometry in metamorphic quartz

Cathodoluminescence (CL) of quartz from metamorphic rocks representing a range of conditions from the garnet grade to the migmatite grade reveals a variety of textures, that is, a function of metamorphic grade and deformation history. Ti concentrations, determined by electron microprobe and ion microprobe, generally correlate with CL intensity (blue wavelengths), and application of the Ti‐in‐quartz thermometer (TitaniQ) reflects the temperature of quartz growth or recrystallization, and, in some settings, modification by diffusion. Quartz from garnet grade samples is not visibly zoned, records temperatures of 425–475 °C, and is interpreted to have recrystallized during fabric formation. Quartz grains from staurolite grade samples are zoned in CL with markedly darker cores and brighter rims, some of which are interpreted to have been produced by the dominant staurolite‐producing reaction, whereas others are interpreted as having formed by diffusion of Ti into quartz rims. Quartz from the matrix of kyanite and sillimanite grade samples are generally unzoned, although locally displays slightly brighter rims (higher Ti); quartz inclusions within garnet and staurolite have distinctly brighter rims, which are interpreted as having been produced by diffusive exchange with the host mineral. Quartz from migmatite grade samples displays highly variable CL intensity, which is dependent on the location of the grain. Matrix grains in melanosomes are largely unzoned or rarely zoned with darker cores. Leucosome quartz is strongly zoned with bright cores and dark rims and is interpreted as having formed during crystallization of the melt. Locally within the leucosome is observed oscillatory‐zoned quartz, which is interpreted as a subsolidus recrystallization to achieve strain relaxation. Quartz inclusions within garnet or plagioclase crystals often show bright domains separated by zones of dark CL. These enigmatic textures possibly reflect local melting fluxed by fluid inclusions. Temperatures calculated from the Ti–in–quartz thermometer are a function of the metamorphic grade of the sample, the textural setting of the quartz, the reaction history and the deformation history of the rock. The TitaniQ temperatures can be used to constrain the conditions at which various metamorphic processes have occurred.     

Structural state and differusion of impurities in natural quartz of different genesis

Impurity inhomogeneities and other structural defects have been studied by means of transmission electron microscopy (TEM), X-ray microanalysis and electron paramagnetic resonance (EPR) in untreated and heat-treated quartz samples of three genetic types: hydrothermal, pegmatitic and magmatic. The impurities present are Al, Na and H₂O, which occupy tetrahedral (Al³⁺) or interstitial (Na⁺, H₂O) positions in the quartz lattice. Impurities form imperfections of various degrees of segregation: from point defects to micropores with a gas-liquid content. Their size, form, density and distribution in the lattice depend on the formation conditions of the quartz, the presence of dislocations and plane defects serving as sinks for the impurity atoms, and the heat treatment regime. Experimental data indicate that gas-liquid inclusions of dimensions up to some microns are the result of impurity segregation during postcrystallizational cooling. Crystalline quartz amorphizes upon electron irradiation. A model of structural water explaining experimentally observed features of this phenomenon is proposed whereby the water molecule, represented as a dipole, enters microregions of the silica lattice with a high impurity content and there forms a bond between ‘defective’ [SiO₃]^2? and [AlO₄]^5? tetrahedra. On irradiation, the Si---O donor-acceptor bonds trap nonelastically scattered electrons and are ruptured as a result. The water released by this lattice discontinuity forms microbubbles that diffuse along sinks into the larger micropores thus further increasing their volume.