煤中镓的地球化学研究进展

镓是煤中可利用的伴生元素之一。通过研究我国煤田中镓的分布特点,将其在煤层中的富集情况划分为区域富集和全段富集,并从煤岩类型、矿物组成、元素对比等方面分析得出镓在顶底板附近煤层富集时,与煤灰产率、灰中w(Al2O3)等多为正相关关系;当镓富集于其他位置时,该相关性不明显。对相应赋存状态和富集机理的对比分析表明,无机矿物和有机物质对镓在煤中富集有不同的作用意义,在以无机成矿作用为主的背景下,强调有机质在镓的富集初期具有重要作用。煤中镓的物质来源主要为陆源碎屑,后期地下水等作用对其有补充作用。     

广西晚二叠世典型聚煤盆地中锂、镓丰度及富集因素

针对广西晚二叠世聚煤盆地中锂、镓元素地球化学异常问题,选取扶绥和贤按两个典型晚二叠世煤田,通过系统取样测试,研究煤系中锂、镓丰度,并结合成矿地质背景,分析煤中锂、镓的富集控制因素。结果表明:研究区锂和镓均有一定的工业前景,扶绥煤田锂和镓的平均丰度分别为83.5 μg/g和30.8 μg/g;贤按煤田锂、镓丰度分别为199.1 μg/g和33.4 μg/g。锂主要富集于合山组底部K₁煤层、炭质泥岩及铝土岩段,而镓在合山组底部各岩性中的丰度并无明显差异。云开古陆及周边中酸性火山岩是锂、镓物质的基础来源,合山组底部高铝沉积岩系可能是合山组K₁煤层中锂、镓的直接物源。镓元素在各岩体之间的迁移比较活跃,其物源区的含量水平起主导作用,而锂元素的富集除了受控于物源外,沉积环境及后期地质作用的影响更为明显。研究成果为广西煤系中锂、镓资源的勘查预测及其综合利用提供科学依据。      

豫西地区铝土矿中镓的分布规律研究

镓是一种价格昂贵的稀散金属，其应用前景十分广阔。豫西地区的铝土矿石中含有丰富的镓资源。通过对区内铝土矿石中镓的分布特征做了多方面的对比研究，归纳出镓的分布规律：空间上，在不同铝土矿区的矿石中镓的平均质量分数变化显著，在矿体平均厚度最大的张窑院矿区，矿石中的镓高度富集。时间上，沉积成矿相对较早的铝土矿层，因其长期遭受强烈的表生富集作用，矿石中镓的平均品位较高。从矿石结构类型来看，土状和峰窝状矿石中的镓品位明显高于短、鲕状和致密状矿石。另外，矿石中镓平均含量的变化总与铝土矿富矿体的产出位置关系密切。并且，探讨了铝土矿中镓分布规律的控制因素。     

镓矿资源需求趋势分析与中国镓产业发展思考

镓是一种伴生矿,主要与铝、锌、锗的矿物伴生,没有独立的矿床,我国金属镓资源储量丰富。作为重要的半导体材料,镓广泛地应用于无线电通讯、光纤通信、汽车雷达、LED照明、太阳能电池等领域,且金属镓所有用途几乎都和当前现代科技发展及低碳经济、绿色能源和环境保护相关。随着镓消费量的不断增长以及镓应用领域的拓展,金属镓的重要性已经被越来越多的国家注意。本文采用部门分析法分别预测镓在砷化镓、LED、薄膜太阳能领域的应用,预测出全球2020年镓金属需求约410~430 t,并对中国镓产业发展面临的问题进行分析,提出增强下游镓产品竞争力、保护镓金属产能的政策建议。     

贵州铝土矿伴生镓的分布特征及综合利用前景——九论贵州之铝土矿

镓是甚为分散的元素,由于镓和铝的性质相近,大量镓伴生于铝土矿中。在黔中-渝南成矿带内,除修文矿带铝土矿镓平均含量为63×10-6外,息烽、遵义、正安、道真矿带铝土矿中镓平均含量为114×10-6~129×10-6。铝土矿中镓含量高低,可能与其基底地层岩石中镓含量的高低关系密切。贵州铝土矿中镓的平均含量皆大大超过铝土矿中镓的综合利用指标,有着广泛的开发利用前景。     

中国镓矿分布规律、成矿机制及找矿方向

金属镓资源是我国优势资源, 但随着国内外需求量不断增大, 我国金属镓的后备资源逐步短缺。本文系统搜集了我国富镓矿床研究和勘查成果资料, 初步总结了我国富镓矿的分布规律、成矿机制和找矿方向。研究认为, 我国镓矿主要伴生在铝土矿、煤矿和铅锌矿之中, 以铝土矿中伴生镓最为重要。依据不同成矿作用将我国具有工业价值的富镓矿床划分为沉积型铝土矿、堆积型铝土矿、红土型铝土矿、煤矿床和碳酸盐岩型(MVT)铅锌矿等5种伴生镓矿床类型, 并总结了不同类型镓矿床的时空分布规律。时间上, 我国富镓矿床在元古宙、古生代、中生代和新生代均有发育, 以石炭纪—三叠纪、侏罗纪—白垩纪和第四纪为主。其中, 富镓铝土矿主要形成于石炭纪、二叠纪和第四纪, 以石炭纪最为重要; 富镓铅锌矿主要形成于震旦纪和寒武纪; 富镓煤矿主要形成于石炭纪和二叠纪。空间上, 我国富镓矿床主要分布在晋豫成矿区、右江成矿区、扬子陆块西南成矿区、川—滇—黔成矿带、湘西—鄂西成矿带、湘东—赣西成矿带和华北陆块北缘成矿区等7个区带中。不同类型富镓矿床的成矿机制不同, 一般在风化-沉积作用下形成富镓铝土矿, 镓与铝常以类质同象形式存在; 在生物化学沉积作用下形成富镓煤矿, 镓常以无机态、有机态和混合形式存在, 在我国多以无机态的形式赋存于勃姆石、硬水铝石等矿物中; 在热液作用下形成富镓铅锌矿, 镓可能以类质同象形式进入以闪锌矿为主的硫化矿物晶格中。根据不同镓矿的成矿作用、富集过程和地质背景, 建立了煤矿、铅锌矿和铝土矿中镓富集成矿的理想模型, 并对铝土矿、煤矿和铅锌矿中伴生镓矿进行了找矿预测, 提出了找矿方向和重点找矿区域, 其中以沉积型、堆积型铝土矿的找矿为主攻方向, 并可兼顾煤矿和铅锌矿等其他伴生镓矿床。     

临兴地区太原组下段煤系泥页岩中战略性金属元素镓富集特征及成因分析

鄂尔多斯盆地东缘临兴地区太原组下段煤系泥页岩中镓富集,镓含量平均为24.7 μg/g。泥页岩中镓含量在平面上表现为研究区北部、西南部靠近紫金山岩体,镓含量降低。研究区太原组下段煤系泥页岩中镓主要以类质同象取代铝的形式赋存于高岭石中,碎屑中的碱性长石是镓的另一种重要赋存矿物。通过元素地球化学分析,认为阴山造山带花岗岩系是富镓泥页岩的主要物源。加里东期华北克拉通长期缓慢稳定隆升,为源岩风化形成富镓物源提供了有利的构造环境。风化和沉积条件是泥页岩中镓富集的控制性因素,包括温暖湿润、间歇性干热的气候,淡水为主、缺氧还原的沉积环境。成岩期,煤系有机质热演化释放出大量有机酸,溶蚀碱性长石碎屑并将其中的镓释放,致使镓元素进一步富集。由于煤系中煤层—泥页岩—砂岩组合体系的开放性较差,镓在成岩期的富集不能持续进行。研究区泥页岩中镓的富集过程以陆源富集型为主。成岩改造作用在一定程度上促进镓元素进一步富集。岩体侵位导致了低熔点的镓在温度作用下发生迁移,导致靠近紫金山岩体的镓含量降低。     

川南煤田古叙矿区石屏一矿煤中锗、镓元素分布特征及其影响因素

石屏一矿作为川南煤田古叙矿区内重要的生产矿井,其煤炭资源丰富并蕴含锗、镓等稀散金属。为探究煤中锗、镓的分布、赋存情况及其影响因素,通过收集川南煤田石屏一矿的地质勘查资料,综合整理分析煤中锗、镓的测试成果并总结其分布规律,建立锗、镓与灰分、挥发分和全硫的相关性研究,从而达到研究目的。结果表明：平面上,锗含量基本稳定,平均为3.4 ug·g^-1,处于正常水平;垂向上,随着煤层埋深的增加,锗含量呈升高趋势,其中C25煤层中锗含量较高,平均为6.4 ug·g^-1,为轻度富集;平面上,镓含量为5～50 ug·g^-1,平均值为22.2ug·g^-1,在矿区北部和中部已达最低工业品位;垂向上,各煤层中镓均达到轻度富集,其中C13煤层中镓含量最高,平均为30.5 ug·g^-1;煤中镓主要受到灰分的影响,且镓主要表现为无机亲和性,其可能以粘土矿物为载体;而锗具有机亲和性,其可能与酚羟基结合而赋存于有机质中,且一小部分锗还可能赋存在硫铁矿硫、硫酸盐硫或有机硫中。安静、低能的海相沉积环境(泻湖)中形成...     

西南某含煤区晚二迭世含煤沉积中镓的地化行为及其分布特征

由于镓及其化合物在电子技术和光电子技术以及其它方面的重要用途,近20年来,对镓的需求量急剧增加,一些国家对镓的普查和提取的研究相当重视。关于镓的地球化学的研究也有了较大发展。但是,对于煤中镓的存在形式、分布规律,镓在含煤沉积过程中的行为等方面的研究很少。      

豫西杜家沟铝土矿中镓的分布规律及控制因素浅析

镓是一种价格昂贵的稀贵金属，它的回收利用问题逐渐引起人们的重视。在对杜家沟铝土矿床矿石中镓的分布特征做了多方面对比研究的基础上，归纳出镓的分布规律：空间上、镓在不同层位的矿石中平均含量变化显著，镓含量随着矿层平均厚度的增大而增大。遭受强烈的表生富集作用，铝土矿中镓的平均品位较高。从矿石结构类型来看，蜂窝状矿石中的镓品位明显高于豆、鲕状和致密状矿石。另外，另外，矿石中镓的含量总与富矿体关系密切。     

我国主要硫矿床类型及成矿若干规律

我国硫矿资源丰富多采,有自然硫、硫化氢、硫铁矿、石膏、明矾石等。对于这些矿产中的主要矿床类型地质特征总结归纳,显然将有助于提高地质理论水平和扩大找矿远景。成矿规律是成矿地质条件的全面反映,矿质来源则为成矿地质的前提和物质基础。本文拟从物质来源探索出发,提出以下硫矿床的分类方案。     

庐枞盆地龙桥铁矿床中菱铁矿的地质特征和成因意义

龙桥铁矿床是庐枞火山岩盆地中的一个大型的铁矿床,多年来对其矿床成因的认识存在较大的争论.文章在野外地质研究工作的基础上,通过对矿床中菱铁矿的岩矿分析鉴定和电子探针测试,确定了矿床纹层状矿石中的菱铁矿为沉积成因.通过对菱铁矿的产出特征分析,并结合龙桥铁矿床的部分地质地球化学研究成果,认为在该矿床形成过程中,早期沉积形成了纹层状的菱铁矿层,在燕山期的岩浆热事件中,部分沉积菱铁矿被交代形成了磁铁矿和具有残余骸晶结构等一系列矿石交代组构特征的矿物.纹层状矿石既具有沉积特征,也具有热液改造特征,证实了矿床的形成存在早期(三叠纪)的沉积成矿(菱铁矿)作用和晚期(燕山期)的热液成矿(磁铁矿)作用.菱铁矿的研究为进一步确定龙桥铁矿床的成因提供了新的佐证.     

Genesis of nickel laterites and bauxites in greece during the jurassic and cretaceous, and their relation to ultrabasic parent rocks

Nickel laterites and bauxites, including their proposed parent rocks from the Mesozoic of Greece, have been investigated by means of mineralogical and geochemical methods. The results are discussed in order to recognize the genetic sequence which comprises: pre-lateritic alteration and reworking of ophiolites and associated rocks, lateritic in-situ weathering, reworking and redeposition of the alteration products in an epicontinental transition environment, and post-depositional events affecting the mineralogical and geochemical properties.The ultramafic massifs of the Euboea and Locris area, i.e. the parent rocks of the Ni---Fe deposits, are primarily harzburgites which represent the erosional outliers of a probable “complete” ophiolitic nappe that were transformed to a monomineralic lizarditite. Xenoliths of basic and sedimentary rocks are included in the serpentine matrix of the basal tectonic melange. Lateritic Ni---Fe deposits resting as in-situ alterites on ophiolites or as mechanically reworked laterite detritus, either on serpentinite or karstified limestone, are mainly derived from serpentinites. The ore deposits in the Locris area have been affected by a strong supergene epigenetic overprint, mainly resulting in a downward Ni redistribution and enrichment. A continuous transition from karstic Ni---Fe deposits towards bauxitic material in a southern direction is interpreted as sedimentary admixture of weathering products of different origin.The three bauxite horizons B₁, B₂ and B₃ and their satellite horizons are intercalated in epicontinental shallow-water limestones within an Upper Jurassic to Middle Cretaceous sequence. A karstic surface (unconformity) forms the substratum of these bauxite horizons.Similar to nickel laterites on karst, the detrital parent material was transported from a terrestrial hinterland by widely ramified river systems into a brackish lagoonal or marine environment from a northeastern to southwestern direction. Colloidal matter, fine muds and coarse material were deposited on a karst topography in mechanical traps by successive debris flows during cycles of emersion and marine regressions.Diagenesis resulted in (a) leaching of silica and iron under partly reducing conditions, and (b) recrystallization of iron minerals and neoformation of Al minerals, i.e. boehmite and/or diaspore. During tectonic subsidence and early marine transgression a strong supergene-epigenetic downward mobilization of Fe, Mn and associated elements took place. They were reprecipitated near the footwall in chemical traps.Bauxites of all horizons originate from serpentinites as well as from metamorphic and magmatic rocks. This is indicated by a high content of siderophile elements and lithic components. The sequences of regression and transgression and their erosional, sedimentary and geochemical processes are interpreted as cyclic events.     

Characterization of bauxite deposits from Kachchh Area,Gujarat

The bauxites deposits of Kachchh area in Gujarat are investigated to characterize them based on mineralogical and petrographic studies. The major bauxitic mineral in these occurrences is gibbsite, with minor concentration of boehmite and diaspore. Apart from the bauxitic minerals, the other associate minerals are kaolin, calcite, alunite and the iron ore minerals such as hematite and goethite and titanium rich anatase. The iron ore minerals (hematite and goethite) are 10-50microns in size and are disseminated throughout the oolitic and pisolitic bauxitic minerals. At places the goethite exhibits colloform texture. The preservation of basaltic texture in some of the samples indicate that the insitu nature of these bauxites, which are formed by the alteration of calcic plagioclase from the parent basalt. Although, the basalt occurs as the main parent rock for these bauxites, the presence of calcite in some of the samples represent the possibility of having a limestone parent rock at least in some of the bauxite occurrences.     

湖南沃溪钨-锑-金建造矿床同生成因的微量元素和硫同位素证据

对岩矿石和矿物的微量元素、稀土元素和硫同位素地球化学的研究表明,湖南沃溪钨-锑-金建造矿床系海底同生热水沉积作用的产物。矿石与围岩中微量元素和稀土元素含量的变化关系,反映了一种复杂的热液、海水以及陆源碎屑的联合影响。矿石及其中矿物(石英)的稀土元素配分模式可与许多沉积喷流型(sedex型)块状硫化物矿石及其共生的喷流岩相对比,暗示了两者具有相似的形成机理。矿石的硫同位素资料显示,生物成因硫与热液成因硫(下伏沉积柱中硫化物的溶解和/或部分海水硫酸盐的还原)共同参与了成矿作用过程。     

Mineralogy,geochemistry and origin of Mn in the high-Mn iron ores,Bahariya Oasis,Egypt

Although Mn is one of the major impurities in the economic iron ores from the Bahariya Oasis, information on its modes of occurrence and origin is lacking in previous studies. High-Mn iron ores from El Gedida and Ghorabi–Nasser iron mines were subjected to detailed mineralogical, geochemical, and petrographic investigations using X-ray diffraction (XRD), infrared absorption spectrometry (IR), Raman spectroscopy, X-ray fluorescence (XRF), scanning electron microscopy (SEM), and electron probe microanalyzer (EPMA) to clarify the modes of occurrence of Mn in these deposits and its origin. The results showed that the MnO₂ contents range between 0.03 and 13.9 wt.%. Three mineralogical types have been identified for the Mn in the high-Mn iron ores, including: (1) inclusions within the hematite and goethite and/or Mn accumulated on their active surfaces, (2) coarse-grained and crystalline pyrolusite, and (3) fine-grained cement-like Mn oxide and hydroxide minerals (bixbyite, cryptomelane, aurorite, romanechite, manjiroite, and pyrochroite) between the Fe-bearing minerals. The Mn carbonate mineral (rhodochrosite) was detected only in the Ghorabi–Nasser high-Mn iron ores. Since IR patterns of low-Mn and high-Mn samples are almost the same, a combination of XRD analysis using non-filtered Fe-Kα radiations and Raman spectroscopy could be the best way to identify and distinguish between different Mn minerals.Assuming that both Fe and Mn were derived from the same source, the occurrence of high-Mn iron ores at the base of the stratigraphic section of the deposits overlain by the low-Mn iron ores indicated a supergene origin of the studied ores by descending solutions. The predominance of Mn oxide and hydroxide minerals in botryoidal shapes supports this interpretation. The small grain size of Mn-bearing minerals as well as the features of microbial fossils such as spherical, elliptical, and filamentous shapes of the Fe-bearing minerals suggested a microbial origin of studied iron ores.Variations in the distribution and mineralogy types of Mn in the iron ores of the Bahariya Oasis demanded detailed mineralogical and petrographic characterizations of the deposits before the beneficiation of high-Mn iron ores from the Bahariya Oasis as feedstock for the ironmaking industries in Egypt by magnetizing reduction. High Mn contents, especially in the Ghorabi–Nasser iron ore and occurrence of Mn as inclusions and/or accumulated on the surface of the Fe-bearing minerals would suggest a possible utilization of the high-Mn iron ores to produce ferromanganese alloys.     

Geochemistry of the Pegmatitic Rocks and Minerals in the Kenticha Belt, Southern Ethiopia: Implication to Geological Setting

Trace element distribution patterns are reported for whole rocks (granites, aplites, greisens, pegmatites, alaskites) and minerals from the Kenticha pegmatite field. The data shed light on the evolution, regional and local zonal pattern of the granitepegmatites and associated mineralization in the Kenticha belt. The complex mineralization of commercial concentrations of Ta, Nb, Hf, Zr, REE, U and Th is related to Be, Li, Cs, Rbbearing zones of pegmatites and is structurally controlled. Whole rock chemical signatures of the suite of felsic rocks of the Kenticha belt are predominantly similar to those generated by subduction in modern magmatic arcs and indicate a mantle derivation. Columbotantalite concentrates extracted from the pegmatitic ores represent the basic raw materials from which a number of possible byproducts can be recovered.     

河南伊川石佛寺铝土矿地质特征及控矿因素

河南伊川石佛寺铝土矿是近年在豫西地区龙门-巩义铝土矿成矿带新发现的中型铝土矿床之一.矿床含矿岩系为上石炭统本溪组中下部,铝土矿呈层状产于寒武系崮山组碳酸盐岩古风化剥蚀面,与上覆太原组整合接触.矿床赋存的本溪组从下而上分别由含铁黏土岩和铝土矿层组成.铝土矿体直接顶板为一1煤,厚约0.80～1.60 m;直接底板为高铁铝质...     

Chloriniferous minerals and certain problems in genesis of metasomatic magnetite ore deposits in Mul'ga-Burluk and Krasnokamenka groups,Eastern Sayan

Accumulations of magnetite ores in contacts of compositionally and chronologically different intrusions, with their different sedimentary host rocks and anomalously high chlorine content of certain minerals associated with the ores, suggest the possibility of a common source of iron in the magnetites and a common source of chlorine in the minerals, with allowances for a degree of assimilation of Fe and Cl from the hosts. The ferruginous Kuvay series at the base of the section may have functioned as the source of iron for the magnetite deposits. Chlorine, an important carrier of iron, under the given conditions may have been borrowed by the magmatic solutions from the saline rocks in the depths. —V.P. Sokoloff.