996 resultados para mineralogy


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Distributions of elements especially hazard trace elements in coals and their wastes from a coal fired power plant have been studied in detail using knowledge of Geology, Mineralogy, Geochemistry and Environmental chemistry. The key work is on the small particle sizes of fly ashes which escaped from electric precipitator and discharged into atmosphere. By means of X-ray powder diffraction (XRD) and scanning electron microscopy with energy-dispersive spectrometer (SEM-EDS), the characteristics of minerals and morphologies were studied. Different types of fly ash were formed in different stages and processes. More than 50% of small fly ashes belonged to inhalable particles (PM10). The very fine fly ashes preferred to attach on surface of bigger fly ash or conglutinate with each other and this decreased the environmental impact of tiny fly ashes. The trace elements in coal, fly ashes, slags and small particle sizes of fly ashes had been analysed by means of Neutron Activation Analysis (INAA), inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma atomic emission spectrometry (ICP-AES). As particle sizes decreasing, distributions of most elements increased, but in contrary to most studies, this increasing trend was not very obviously because of the tendency of attachment of tiny fly ashes. The occurrence of 30 elements including hazard trace elements of Cd, Cr, Ni, Co, Pb, Zn, As, Se, Cu, V was studied by means of sequential chemical extract. The annual discharge of hazard trace elements of slag, fly ash, small fly ash (PM10), tiny fly ash (PM2.5) and air was calculated by mass balance. S, V, Cu, Pb, Se, Mo, Cd from power plant had potential impacts on environment. Hazard trace elements from the power plant had little effect on soil and aerosol comparing to those from other industrial sources and the effects were mostly on downwind direction. Both the high performance electric precipitator and high chimney made the hazard trace elements from power plant being transported far away but little environmental impacts.

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Chinese National Antarctic Research Expedition (CHTNARE) has collected 4480 meteorite specimens in the Grove Mountains, East Antarctica, from 1998 to 2003. According to the location characteristics and the diversity of the classification, the paper concludes that the Grove Mountains is another important meteorite concentration area in the Antarctica. The Concentration mechanisms at the site could be related to the last glacier activity and katabatic wind. An empirical model was proposed: 1) Probably during the Last Glacial Maximum, ice flow overrided the Gale Escarpment range in the area. Formerly concentrated meteorites were carried by the new glacier and stayed in the terminal moraine when the glacier retreated. 2) Blown by strong katabatic wind, Newly exposed meteorites on the ablation zone were scattered on the blue ice at the lee side of the Gale escarpment. Some of them would be buried when they were moved further onto the firn snow zone. Many floating meteorites stopped and mustered at the fringe of the moraine. The chemical-petrographic of 31 meteorites were assigned based on electron probe microanalyses, petrography and mineralogy, including 1 martian lherzolitic shergottite, 1 eucrite, 1 extreme fine grain octahedron iron meteorite, and 28 ordinary chondrites (the chemical groups: 7 H-group, 13 L-group, 6 LL-group, 2 L/LL group; the petrographic types: 6 unequilibrated type 3 and 22 equilibrated type 4-6). GRV99028 meteorite has the komatiite-like spinifex texture consisting of acicular olivine crystals and some hornblende-family minerals in the interstitial region. Possibly it has crystallized from a supercooled, impact-generated, ultramafic melt of the host chondrite, then experienced the retrogressive metamorphism. Four typical chondrule textures were studied: porphyritic texture, radiative texture, barred texture and glass texture. The minerals are characteristically enriched in MgO content.

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在新元古代-寒武纪交替阶段(~544Ma)的短短几百万年间,生物种类和数量剧增,这一事件被称之为“寒武纪生物大爆发”(Cambrian Exploration),同时在这一时期,也发生了全球的海洋缺氧事件(Ocean Anoxic Event,OAE)。这些事件造成了在世界范围内的寒武系底部普遍发育了一套富有机质的黑色岩系。在中国南方,从皖南、浙江经赣北、湘西北、贵州至云南一线,下寒武统黑色岩系的分布近2000公里。这些黑色岩系的发育程度在全球背景中很具特色,是全球背景中研究黑色岩系及其相关科学问题的理想场所。 我国南方大陆早寒武世黑色岩系广泛分布且层位稳定,并伴有Mo、Ni、Se、V、Ag、Au、PGE等多种元素富集层。由于其处在特殊的地球演化背景及地质条件,成为目前国内外研究的一个热点区域。基于此,本文在前人工作的基础上,以贵州遵义地区早寒武世黑色岩系中镍钼多金属富集层为研究对象,通过矿物学、元素地球化学、同位素地球化学等研究手段,探讨中国南方早寒武世黑色岩系中镍钼多金属富集层的成因机制。通过研究,取得以下几点认识: (1) 下寒武统镍钼多金属富集层中SiO2含量较低,MgO、Na2O、K2O、MnO、TiO2在炭质页岩和镍钼层中含量差别不大。镍钼多金属富集层中Fe、Ca、P的含量明显高于碳质页岩,这与镍钼层中硫化物、方解石和磷质的显著增加有关。 (2) 镍钼多金属富集层中微量元素Se、Mo、Cd、Ag、Tl、U、Ni,、Bi、Zn、Cu、V等均有较大富集,富集系数为n到n×103。其中尤以Se、Mo最为富集,两者的富集系数均超过30000,其中Mo元素的富集系数大于50000。 (3)通过多种地球化学指标判别,如Se在黑色岩系中超常赋存,U/Th比值远大于1,黑色页岩和镍钼多金属富集层的Ce具有负异常、Eu有微弱的正异常,多种成矿元素的相关关系等这些特征,都暗示了海底喷流热液和生物的共同作用。此外,黑色岩系中V/(V+Ni)的比值反映了它的沉积环境为缺氧环境。 (4)研究区下寒武统黑色岩系中镍钼多金属富集层的矿物组合以黄铁矿、白铁矿、针镍矿、辉砷镍矿、铁辉砷镍矿、紫硫镍矿、赫硫镍矿和碳硫钼矿为主。 矿物生成大多经历了两个成矿阶段:沉积-早期热液阶段和热液-生物阶段。 (5)根据电子探针分析,对于主要富集元素Ni、Mo而言,Ni以出现大量的镍矿物为特征。镍钼多金属富集层中Mo元素主要以“碳硫钼矿”(MoSC)的形式赋存。Se与As元素在硫化物中含量变化十分特征,如在黄铁矿中Se元素较少而As元素含量较高,在碳硫钼矿中情况相反,推测这是由于Se与As元素不同的地球化学性质以及上述两种矿物不同的形成期次造成的。 (6)同位素研究表明,镍钼多金属富集层的硒同位素的分布范围较窄,δ82/76Se范围为-1.56‰- +1.85‰,平均值+0.25‰。根据目前所测得的硒同位素数据,不支持从海水中还原金属元素沉积富集的机制。我们认为当硒通过海底喷流作用释放后,首先以类质同象的方式结合到硫化物相中,这一过程不会造成硒同位素的大的分馏。流体中剩余的少部分硒与海水混合,并且为藻类吸附而沉淀下来,这一过程会造成约1-2‰的硒同位素分馏。这一模式可较好的解释遵义地区下寒武统Ni-Mo-Se富集层的硒同位素组成特征和硒在不同物相中的分配形式。 (7) 镍钼多金属富集层和围岩的有机碳含量为1.75%~13.9%,平均9.16%,有机碳同位素组成为(δ13Corg)-30.6‰~-32.2‰,这一负偏移可能是由于寒武纪早期的海侵作用造成的。

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白牛厂矿床是超大型银多金属矿床,除银储量(>7000t)达到超大型规模外,铅、锌、锡储量均达大型规模,同时伴生大量的分散元素(In、Cd、Ge、Ga等)。矿床位于滇东南个旧和都龙矿田之间,赋存于华南加里东褶皱系滇东南褶皱带西北缘的中寒武统细碎屑岩系之中,北西面以弥勒断裂与扬子地块分界,南西以红河断裂为界与哀牢山断块毗邻,南连越北古陆,东部文麻断裂与南岭褶皱系连为一体,区内地质构造、岩浆活动和矿化作用均较复杂,各构造单元的构造演化对白牛厂银多金属矿床均有不同程度的影响。 白牛厂银多金属矿床自80年代后期被发现以来,已有多家单位和个人在该区开展了一系列的研究工作。但是,在成矿物质及流体来源、矿床成因、矿床与花岗岩的关系等方面都存在诸多争议。本文在深入细致的野外地质工作基础上,对矿石进行了系统的显微镜鉴定,并对部分矿物做了电子探针定量及面扫描分析,详细研究了矿床成矿元素特征及主量元素、微量元素、稀土元素、同位素地球化学特征,主要取得以下结论性成果: 1. 银矿物的赋存状态及形成阶段。银主要以硫盐或复硫盐矿物的形式出现,方铅矿是主要的载银矿物。原生银矿物明显分为两组:一组为Ag的黝铜族矿物和Ag的锑硫盐矿物,产于方铅矿的内部或与方铅矿连生形成文象状连晶,与方铅矿具有相似的物源,属热水沉积成因;另一组为Ag的锡硫盐矿物,产于方铅矿边部,往往伴随锡石、黄锡矿、辉锑锡铅矿产出,可见黄锡矿交代锡石形成镶边结构,暗示了其岩浆热液成因。 2. 花岗岩特征及其与成矿的关系。白牛厂矿区花岗岩具有富硅、富碱及高钾低钠特点,属铝过饱和钙碱性岩,与花南改造型花岗岩相似,属同碰撞S型花岗岩,成岩物源主要是基底变质岩重熔作用形成的花岗岩浆,Ag、Pb、Zn、Sn等成矿元素含量较高;与矿石稀土元素对比研究表明,花岗岩稀土配分模式与矿区东南部穿心洞、对门山和阿尾矿段矿石相似,而与矿区西北部白羊矿段矿石相差较大,暗示后期岩浆叠加改造作用主要发生在矿区东南部诸矿段。   3. 矿床含矿沉积建造地球化学特征。通过与中国大厂、个旧典型热水沉积硅质岩,加拿大沙利文矿山的条带状富电气石热液沉积岩和加拿大Agnico-Eugle矿山的铁建造中的条带状燧石岩以及现代海底热水沉积物对应的主量元素、微量元素及稀土元素对比研究,为白牛厂矿床含矿沉积建造提供了热水沉积成因的地球化学证据,指出该区中寒武世可能发生了广泛的热水沉积事件。   4. 成矿物质及成矿流体来源。系统的铅、硫同位素研究表明,中寒武世热水沉积成矿期金属成矿元素及硫主要是由下地壳古老变质岩淋滤出来的;燕山期花岗岩也在矿区东南部叠加改造较强的部位提供了Sn等部分金属成矿元素及硫。碳、氧同位素及矿石稀土元素反映矿床早期成矿流体源于深部岩浆,晚期主要来源于燕山期花岗岩浆。   5. 矿床分散元素特征。分散元素In、Cd、Ga含量较高,平均含量分别为33.21×10-6、389.8×10-6、10.18×10-6,初步估计该矿床In、Cd、Ga储量分别大于180t、20000t、600t,闪锌矿是分散元素In、Cd、Ga主要的载体矿物。 6. 可能的矿床成因模式。白牛厂银多金属矿床是长期以来多种地质作用综合的产物,具有多来源、多期次成矿特点,经历了广泛且具有重要成矿意义的中寒世热水沉积成矿作用和燕山晚期岩浆热液叠加改造作用,热水沉积成矿作用形成了层状、似层状矿体,燕山期岩浆热液在矿区东南部对矿床强烈叠加改造,白牛厂银多金属矿床应属“热水沉积+岩浆热液叠加改造”成因。

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都龙锡锌多金属矿床位于云南省马关县都龙镇,是我国最大的锡石硫化物矿床之一。在野外地质和岩矿鉴定基础上,本文对该矿床的绿泥石、鲕状黄铁矿、磁黄铁矿异构交生体、铁闪锌矿的“黄铜矿疾病”等矿物和特殊组构,开展了比较系统的电子探针、拉曼光谱和X光衍射等微束分析,结合对该矿床的黑云母Ar-Ar年代学、锡石TIMS法U-Pb年代学研究,基本明确了矿床各个成矿期次的具体成矿特点,丰富和完善了该矿床的成矿模式。论文取得的主要认识有: (1)绿泥石与锡矿化同为燕山期岩浆热液作用的产物。绿泥石的形成温度(231~304oC)和环境(还原环境)表明,岩浆热液叠加成矿环境为中、低温的还原环境。 (2)鲕状黄铁矿为热水沉积期的特征矿物,是Fe、Zn、S等成矿元素的主要物源。 (3)磁黄铁矿主要在区域变质晚期,由黄铁矿(主要为鲕状黄铁矿)变质脱硫而成。辣子寨矿段单斜磁黄铁矿的出现,说明燕山期岩浆热液叠加成矿温度在该矿段以中低温为主。 (4)铁闪锌矿的“黄铜矿疾病”主要是黄铜矿交代铁闪锌矿的结果,其中的Fe主要来自变质期形成的铁闪锌矿和磁黄铁矿,而Cu主要来自岩浆热液。 (5)自然铋、自然银、锡石、黄铜矿、方铅矿等矿物广泛共生,且交代、穿切其他矿物,表明岩浆热液期的成矿元素组合主要为Bi+Ag+Sn+Cu+Pb。在该矿床首次发现的自然铋和自然银,指示岩浆热液期为低硫、中低温的还原环境。 (6)利用远红外(IR-Laser)阶段加热技术,获得黑云母的低温段和高温段坪年龄,分别为179.0± 5 .0Ma和195.7± 6.6Ma。在黑云母组构显微分析的基础上,认为179.0± 5 .0Ma大致代表了变质成矿作用的年龄。 (7)都龙锡锌多金属矿床属于多成因复成矿床,其形成主要经历了热水沉积、变质改造和岩浆热液叠加三个过程。热水沉积成矿作用形成的鲕状黄铁矿,可能是后期成矿作用中Fe、Zn、S等成矿元素的主要物源。变质改造成矿作用与印支期晚期区域变形-变质作用有关,形成了大量铁闪锌矿、磁黄铁矿,可能对应于造山后伸展事件。岩浆热液叠加成矿作用与燕山晚期老君山花岗岩有关,发生大规模的锡、铜、银、铅、铋矿化。 另外,本次研究在该矿床中首次发现了自然铋、自然银等自然元素,其矿床成因意义有待进一步研究。

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湘西雪峰山地区是湖南最重要的黄金产地,湖南省80%以上的金矿床均赋存在该区前寒武系的浅变质岩中。柳林汊金矿带位于湘西雪峰山中段的北部,尽管该金矿带发现较早,采矿历史很长,但地质工作程度较低。在系统野外调研的基础上,本课题组首次确认柳林汊一带金矿床为典型的钠长石-石英脉型金矿床,明显有别于雪峰山地区其它石英脉型金矿床。本学位论文以该区四个有典型代表性的钠长石-石英脉型金矿为研究对象,在系统野外地质考察和系统采样的基础上,利用矿物学、元素地球化学、同位素地球化学、流体地球化学等研究手段,对该区金矿床的载金矿物—钠长石进行了较详细的矿物学和地球化学研究。在此基础上初步探讨了柳林汊一带金矿床的成矿流体来源、成矿物质来源、成矿时代及矿床成因。本论文主要取得以下几点新认识: 1.柳林汊金矿带金矿床的矿脉中的这些长石呈肉红色,在镜下通常呈板条状、粒状,解理不发育,双晶以聚片双晶为主,负低突起,干涉色一级灰白到一级淡黄。本文首次确认了该区矿脉中的肉红色长石为低温、高有序度的钠长石,该区的金矿类型为典型的钠长石-石英脉型金矿。 2.该区钠长石具Ab含量高,An、Or含量极低等特征,接近纯钠长石。钠长石中Sr 含量相对较高而稀土含量普遍较低,通常为LREE富集型,无明显的Eu、Ce异常。 3.柳林汊一带金矿脉中钠长石的氧同位素组成为10.2‰~14.5‰,对应的成矿流体的δ18O‰为1.9‰~6.9‰。该区成矿流体可能主要来自经演化的大气降水。 4.与钠长石共生的石英中的包裹体主要以液体包裹体为主。其均一温度为140~300℃,盐度为1~8%NaCl,成矿流体的密度为0.60~0.99g/cm3。该区金矿床成矿流体具中低温、低盐度和中等密度等特征。 5.根据本区金矿床的地质特征,并结合前人对湘西地区金矿床的研究成果,提出该区金矿的成矿物质来源为元古宇板溪群,成矿时代为加里东期,矿床的成因类型为层控的热液改造型金矿床。 关键词:柳林汊金矿带 钠长石 矿物学 元素地球化学 流体包裹体 矿床成因

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Wilding, M. C., Benmore, C. J. (2006). Structure and Glasses and Melts. reviews in Mineralogy and Geochemistry, 63 (1), 275-311 RAE2008

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The disposal of industrial waste presents major logistical, financial and environmental issues. Technologies that can reduce the hazardous properties of wastes are urgently required. In the present work, a number of industrial wastes arising from the cement, metallurgical, paper, waste disposal and energy industries were treated with accelerated carbonation. In this process carbonation was effected by exposing the waste to pure carbon dioxide gas. The paper and cement wastes chemically combined with up to 25% by weight of gas. The reactivity of the wastes to carbon dioxide was controlled by their constituent minerals, and not by their elemental composition, as previously postulated. Similarly, microstructural alteration upon carbonation was primarily influenced by mineralogy. Many of the thermal wastes tested were classified as hazardous, based upon regulated metal content and pH. Treatment by accelerated carbonation reduced the leaching of certain metals, aiding the disposal of many as stable non-reactive wastes. Significant volumes of carbon dioxide were sequestrated into the accelerated carbonated treated wastes.

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The increasing volumes of municipal solid waste produced worldwide are encouraging the development of processes to reduce the environmental impact of this waste stream. Combustion technology can facilitate volume reduction of up to 90%, with the inorganic contaminants being captured in furnace bottom ash, and fly ash/APC residues. The disposal or reuse of these residues is however governed by the potential release of constituent contaminants into the environment. Accelerated carbonation has been shown to have a potential for improving the chemical stability and leaching behaviour of both bottom ash and fly ash/APC residues. However, the efficacy of carbonation depends on whether the method of gas application is direct or indirect. Also important are the mineralogy, chemistry and physical properties of the fresh ash, the carbonation reaction conditions such as temperature, contact time, CO2 partial pressure and relative humidity. This paper reviews the main issues pertaining to the application of accelerated carbonation to municipal waste combustion residues to elucidate the potential benefits on the stabilization of such residues and for reducing CO2 emissions. In particular, the modification of ash properties that occur upon carbonation and the CO2 sequestration potential possible under different conditions are discussed. Although accelerated carbonation is a developing technology, it could be introduced in new incinerator facilities as a "finishing step" for both ash treatment and reduction of CO2 emissions.

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Refractive index determination of minerals and gems often requires their immersion in fluids with the same refractive index. However, these natural materials frequently have refractive indices above the ranges of common organic solvents. Most available high refractive index immersion materials are solid at room temperature, toxic, noxious, corrosive, carcinogenic, or any combination thereof. Since the physical properties of ionic liquids can be tuned by varying the cation and/or anion, we have developed immersion fluids for mineralogical studies which are relatively benign. We report here the syntheses of a range of ionic liquids ( many novel) based on the 1-alkyl-3-methylimidazolium cation, which all have refractive indices greater than 1.4, and can be used as immersion fluids for optical mineralogy studies. We further show that for a series of ionic liquids with the same anion, the refractive indices can be adjusted by systematic changes in the cation.

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The sea-cliffs of the Isle of Wight were deposited during a period of overall sea-level rise starting in the Barremian (Lower Cretaceous) and continuing into the Aptian and Albian. They consist of fluvial, coastal and lagoonal sediments including greensands and clays. Numerous episodes of erosion, deposition and faunal colonization reflect condensation and abandonment of surfaces with firmgrounds and hardgrounds. This study focused mainly on shallow marine cycles where variations in clay mineralogy would not be expected, because overall system composition, sediment source, and thermal history are similar for all the samples in the studied section. Instead we found a wide variety of clay assemblages even in single samples within a 200 in interval.

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Microbiologically contaminated water severely impacts public health in low-income countries, where treated water supplies are often inaccessible to much of the population. Groundwater represents a water source that commonly has better microbiological quality than surface water. A 2-month intensive flow and quality monitoring programme of a spring in a densely settled, unsewered parish of Kampala, Uganda, revealed the persistent presence of high chloride and nitrate concentrations that reflect intense loading of sewage in the spring’s catchment. Conversely, thermotolerant coliform bacteria counts in spring water samples remained very low outside of periods of intense rainfall. Laboratory investigations of mechanisms responsible for this behavior, achieved by injecting a pulse of H40/1 bacteriophage tracer into a column packed with locally derived granular laterite, resulted in near-total tracer adsorption. X-ray diffraction (XRD) analysis showed the laterite to consist predominantly of quartz and kaolinite, with minor amounts (<5%) of haematite. Batch studies comparing laterite adsorption capacity with a soil having comparable mineralogy, but with amorphous iron oxide rather than haematite, showed the laterite to have a significantly greater capacity to adsorb bacteriophage. Batch study results using pure haematite confirmed that its occurrence in laterite contributes substantially to micro-organism attenuation observed and serves to protect underlying groundwater.