57 resultados para Al2o3-cao-mgo-sio2


Relevância:

100.00% 100.00%

Publicador:

Resumo:

矿化剂在热液矿床成矿过程中的重要作用一直为人们所关注,矿化剂地球化学行为直接影响成矿元素的富集成矿,不同的矿化剂元素可能对金属成矿具有一定的专属性。本文以著名的江西德兴铜厂超大型斑岩铜矿床和大吉山钨矿床作为研究对象,研究F、Cl与W、Cu成矿的关系。主要的认识如下:(1)F在花岗质岩浆中,可以降低岩浆的粘度、密度、固液相线温度、改变熔体结构,而Cl对熔体结构没有多大的影响。F在流体一花岗质熔体相间,绝大多数配分系数小于1.0,趋向于熔体相中配分,DF随体系中F浓度的升高而增加。Cl在流体一花岗质熔体相间的配分系数均大于1.0,且Dc1 随体系中Cl浓度的升高而增大·Cl强烈地趋向富集于流体相中。(2)Cu在流体一花岗质熔体作用过程中,铜总趋向于流体相中分布(DCu都大于1)。特别是在富Cl流体中Cu浓度较高,说明在富含Cl的热液流体能够从共存的熔体中活化迁移出大量的 Cu,S的加入DCu有降低的趋势。钨趋向于熔体相中富集,其配分系数大多小于1.0。(3)德兴铜厂花岗闪长斑岩属钙碱性系列岩石属I型花岗岩类,具有埃达克岩的特征。岩浆来源于深部,在结晶演化过程中发生了围岩物质的混染,这种高铜含量围岩的混染使成矿物质在岩浆中得到富集,有利于铜的活化、迁移。在铜厂岩体不同的蚀变带中,SiO2、K2O、Cu、Mo等从新鲜斑岩甚至弱蚀变带中带出,而在强蚀变带强烈富集,Cl同样有在强蚀变岩石中富集的趋势;而Na2O、Fe从斑岩体中带出,进入流体相中,流体中大量Fe的存在,有利于铜的沉淀、富集成矿。(4)德兴铜厂斑岩体微量元素和稀土元素地球化学特征表明,该岩体发生了流体一熔体作用,分异出来的流体是一种相对富氯的流体,同时成矿流体的流向是从岩体中心向接触带方向流动。(5)大吉山花岗岩具有高SiO2、A/CNK值,显示过铝质特点。黑云母花岗岩是壳源花岗岩但又受到慢源岩浆或慢源流体的影响。随着花岗岩的演化(从I→II→III)SiO2、K2O+Na2O逐渐增加,ΣFe、Al2O3、CaO、F含量降低,为成矿提供了大量的矿化剂(F)和沉淀剂(Fe、Ca)。Eu负异常从I至III阶段花岗岩逐渐加强,表明该岩浆经历了高度的分异演化。(6)大吉山花岗岩类稀土元素具有“四重效应”配分的特点以及微量元素对玲Rb、Y/Ho、Zr/Hf以及Nb/Ta发生明显分异,暗示在花岗岩岩浆的演化过程中,经历了充分的流体一熔体作用,同时分异出大量富含F、W等矿化剂元素和成矿元素的热液流体,致使钨矿的形成。大吉山石英脉型钨矿的成矿年龄大约在155 Ma。(7)通过对成矿流体和花岗质岩石黑云母、白云母中卤素相对逸度的研究(log(H2O/fHCl)fluid、log(fHF/fHCl)fluid)发现,铜厂斑岩型铜矿床的成矿体系是相对富氯体系,而大吉山石英脉型钨矿床成矿体系相对富氟,同时氟可能主要迁移W、Sn、Nb、Ta等金属元素。(8)结合斑岩型铜矿床成矿流体特征,铜主要以C1的络合物形式存在和迁移,迁移形式主要是CuCl0、CuCl2等。石英脉型钨矿床中,钨主要以钨酸、钨酸盐及其离解形式存在和迁移,如WO42-、HWO4-、NaHWO4、Naw伍.等;在高度富氟的成矿流体中,钨的氟氧络合物(如WO3F-,WO2F42-等)对钨迁移也具有重要的作用。因此,不同矿化剂类型具有一定的成矿专属性,热液铜矿床主要与Cl、S有 关,而热液钨矿床大多与F有关。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Early glasses (about 1066 BC-220 AD) unearthed from Xinjiang of China were chemically characterized by using PIXE and ICP-AES. It was found that these glasses were basically attributed to PbO-BaO-SiO2 system, K2O-SiO2 system, Na2O-CaO-SiO2 system and Na2O-CaO-PbO-SiO2 system. The results from the cluster analysis showed that some glasses had basically similar recipe and technology. The PbO-BaO-SiO2 glass and the K2O-SiO2 glass were thought to come from the central area and the south of ancient China, respectively. The part of the Na2O-CaO-SiO2 glass (including the Na2O-CaO-PbO-SiO2 glass) might be imported from Mesopotamia, while the other part might be locally produced. (c) 2005 Elsevier B.V. All rights reserved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

采用多元统计方法对四川、重庆、贵州、广西、广东地区出土的100余个古玻璃样品的化学成分数据进行了分析处理。结果表明:中国南方和西南地区的古玻璃制品主要由具有中国特色的铅钡硅酸盐玻璃和钾硅酸盐玻璃组成,可细分为五大系统类别:K2O-CaO(~10wt%)-SiO2系统、K2O-SiO2系统、PbO-BaO-SiO2系统、PbO(~25wt%)-BaO-SiO2系统、CaO-PbO(~40wt%)-BaO—SiO2系统。用因子分析探讨了我国汉代南方和西南地区的玻璃本地生产情况,表明该地区在汉代已经拥有自主生产

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Mg0.4Al2.4O4 single crystals with good optical quality were successfully grown by the Czochralski method. The transmission spectrum indicated that the absorption edge of the crystal was at 220nm, while no apparent absorption peaks were found. The X-ray diffraction and DSC curve analysis showed that Mg0.4Al2.4O4 crystal was stable at room temperature. While after annealing in the air and hydrogen atmosphere at about 1200 degrees C,Mg0.4Al2.4O4 decomposed into Al2O3 and (MgO)(0.4)(Al2O3)(x) (0.4 < x < 1.2). The reaction mainly occurred on the crystal surface, barely inside. (C) 2008 Elsevier B.V. All rights reserved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

酸催化剂可以用来催化烃类裂解、重整、异构、烯烃水和、烷基化和酯化等重要化学反应,在石油炼制和石油化工领域有极其广泛的应用。与传统液体酸相比,新型固体酸催化剂具有容易与反应物和产物分离、易再生、不腐蚀反应器、环境污染少等优点,因此研究开发环境友好的新型固体酸催化剂成为国际上催化领域研究的热点。本论文研究新型固体酸催化剂的酸强度和延长催化剂使用寿命的方法,具有很高的工业实用价值和理论意义。 研究了固体酸催化剂在正己烷异构化和异丁醇脱水这两个反应的催化活性,结果显示:1)复合超强酸催化剂,2)Hβ及其负载催化剂,3)负载杂多酸,4)ZrO2·Bi2O3、ZrO2·CaO四类催化剂酸强度较高且强度大小为:1>2≈3>4。氢溢流的引入提高了Pt-SO42-/ ZrO2催化剂在反应中的催化活性,一定程度上弥补了酸强度的不足,也使一些原本没活性的催化剂有了一定的活性,如MOO3催化剂。 研究了异丁烷在12wt%V2O5/γ-Al2O3催化剂上脱氢制异丁烯的反应和异丁烯在50wt%HSiW/SiO2、Amberlyst-15和Amberlyst-35树脂催化剂上的迭代反应,均获得了较好的催化活性。 首次将催化剂表面的疏油性应用在酸催化领域,在硅胶负载的钨硅酸中掺杂不同含量聚四氟乙烯制备出具有一定疏油性的催化剂,用异丁烯迭代反应作为探针反应着重研究了催化剂表面的适当疏油性对催化剂的寿命和产物选择性的影响。结果显示催化剂表面的疏油性不仅提高了C8 =的选择性并且有效延长催化剂寿命。这主要是由于催化剂表面具有适当的疏油性,反应的中间产物C8=易于从具有疏油性的表面脱附,减少了C8=继续在催化剂表面进行连续反应生成C12=和C16=的机会,因此提高了C8=的选择性。这可能促进了更高的产物选择性,低的积炭量和较长的催化剂使用寿命。 研究了催化剂表面的疏水疏油性在醋酸与正丁醇的酯化反应中的应用。结果显示,当酯化反应产物为液相时,催化剂表面的疏水疏油性非常有利于产物从催化剂表面脱附,能有效提高正丁醇的转化率。 关键词:酸强度,钨硅酸,聚四氟乙烯,疏油性,寿命

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Isolated transition metal ions/oxides in molecular sieves and on surfaces are a class of active sites for selective oxidation of hydrocarbons. Identifying the active sites and their coordination structure is vital to understanding their essential role played in catalysis and designing and synthesizing more active and selective catalysts. The isolated transition metal ions in the framework of molecular sieves (e.g., TS-1, Fe-ZSM-5, and V-MCM-41) or on the surface of oxides (e.g., MoO3/Al2O3 and TiO2/SiO2) were successfully identified by UV resonance Raman spectroscopy. The charge transfer transitions between the transition metal ions and the oxygen anions are excited by a UV laser and consequently the UV resonance Raman effect greatly enhances the Raman signals of the isolated transition metal ions. The local coordination of these ions in the rigid framework of molecular sieves or in the relatively flexible structure on the surface can also be differentiated by the shifts of the resonance Raman bands. The relative concentration of the isolated transition metal ion/oxides could be estimated by the intensity ratio of Raman bands. This study demonstrates that the UV resonance Raman spectroscopy is a general technique that can be widely applied to the in-situ characterization of catalyst synthesis and catalytic reactions. (C) 2003 Elsevier Science (USA). All rights reserved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

In this article, monodisperse spherical zirconia (ZrO2) particles with a narrow size distribution were prepared by the controlled hydrolysis of zirconium butoxide in ethanol, followed by heat treatment in air at low temperature from 300 to 500 degrees C. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric and differential thermal analysis (TG/DTA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra, kinetic decay, and electron paramagnetic resonance were used to characterize the samples. The experimental results indicate that the annealed ZrO2 samples exhibit broad, intense visible photoluminescence. The annealing temperature is indispensable for the luminescence of the obtained ZrO2 particles. The emission colors of the ZrO2 samples can be tuned from blue to nearly white to dark orange by varying the annealing temperature.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Chemical weathering intensity of loess deposits is largely determined by three factors: chemical weathering in source regions, grain size and post-depositional weathering. The third factor is influenced by climatic conditions such as precipitation and temperature, and the dust sedimentation rate in the area of deposition. Previous studies have shown that the (CaO+MgO+Na2O)/TiO2 ratio of decarbonated residue from loess is independent of grain size changes and thus is a reliable proxy for chemical weathering. However, the validity of (CaO+MgO+Na2O)/TiO2 to describe changes in monsoon intensity requires further study. In this study, 48 sections over the last glacial-interglacial cycle on the Chinese Loess Plateau were sampled, and the major elemental concentrations of 248 decarbonated residue samples were measured to investigate the utility of the (CaO+MgO+Na2O)/TiO2 ratio as a proxy for changes in monsoon intensity. Results show that the (CaO+MgO+Na2O)/TiO2 ratio, is relatively more sensitive to climate change than other indexes independent of grain size, and is not affected substantially by sedimentation rate. Assuming the weathering regime is relatively stable in the loess source regions, the (CaO+MgO+Na2O)/TiO2 ratio is a reliable proxy for the intensity of summer monsoon. A decreasing (CaO+MgO+Na2O)/TiO2 ratio from northwest to southeast both in loess and paleosols indicates that the Chinese Loess Plateau is in the control of the East Asian summer monsoon during both interglacial and glacial times. In addition, the spatial distributions of (CaO+MgO+Na2O)/TiO2 ratios show a greater north-south gradient during interglacial periods than during glacial periods. This may suggest that the spatial precipitation gradient, controlled by the summer monsoon, is steeper during interglacials than in glacials.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

In this paper, We analyzed the geological and geographical settings of dinosaurs extinction at the end of Cretaceous, especially the effect of the change of the elements contents on dinosaurs extinction. We studied basis on the two typical sections-Cretaceous-Paleocene boundary (Baishantou section (in Jiayin, Heilongjiang province of China) and Arkhara-Boguchan Coal Mine section (in Far East of Russian)) and Longgushan section (in Jiayin, Heilongjiang province of China) mainly. This work provided some evidences for forecasting the effects of global environmental change on bio-circle. The followings are the primary gains: According to the paleo-climate indexes (CaO/MgO,Sr/Ba) and the results of Factor Analysis, we found that there were similar climate in Baishantou section and Arkhara-Boguchan Coal Mine section near the K/E boundary, and both of them took on the trend of temperature declining and precipitation heightening after transitory high-temperature and drought. There are similar change and evlution rule of the elements contents near the boundary in the both sections (Baishantou section and Arkhara-Boguchan Coal Mine section). Both iron group elements and chalcophile elements appeared obvious abnormity. There are not visible correlation between the change of elements contents and climate indexes. This shows that the elements abnormity maybe came from the factors excluding climate or the factors were too many to conceal the influence of climate. --The result of cluster analysis showed that the boundary between BST3-8 and BST3-9 may be the K/E boundary of Baishantou section, and the top of twofold coal were the K/E boundary of Arkhara-Boguchan Coal Mine section which was consistent with accepted conclusion formerly. By contrast of elements contents in dinosaur bones and general organism, in surrounding rock and general sand stone, the regulation of the change of elements contents in dinosaur bones and surrounding rock, we confirmed that dinosaur extinction in Jiayin were relative with the high abnormities of Sr, Ba, Pb, Cr and the low abnormity of Zn, at least, it was them which speeded up dinosaurs extinction. After a series of analysis, we concluded that dinosaurs extinction of this areas tied up with the relative high background values of geo-chemical elements , paleo-climate and disaster incidents. First of all, high background values provided the necessary condition for the accumulation of the elements. Secondly, the drought climate adverse to the survival of dinosaurs, and led them to extinct gradually. finally, disaster incidents, the eruption of volcano or the collision of aerolites, made them exit this planet.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

利用薄片观察、X射线粉晶衍射分析和化学分析方法研究了广西凭祥英安岩风化剖面的形成作用。风化作用初期,母岩中微量黄铁矿的氧化分解导致方解石与绿泥石的迅速分解;风化中期形成了大量的高岭石、伊利石、蒙脱石和蛭石;风化作用高级阶段以高岭石、石英和氧化铁矿物的富集为特征,但仍然存在少量蒙脱石、伊利石和蛭石。风化剖面的部分层段显示出与剖面其他部分明显不同的地球化学特征,即Na的富集和K的亏损。在Al2O3-(CaO+Na2O)-K2O三角图上,风化中期这些层段明显偏离了正常的风化趋势。矿物学和微形貌的研究表明,造成偏离的原因是古地下水引起的正长石的钠长石化作用。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

应用改善了的质量平衡方程研究冬瓜山层控夕卡岩型铜矿床成矿系统的元素活动性及质量迁移,结果表明:系统中Zr ,Hf ,Y和Nb 为不活动元素,其余均为活动元素。主量元素中仅CaO 为迁出组分,其质量迁移量为84 % ,其余均为带入组分,带入量最大的SiO2 的质量迁移量高达2384 %;稀土元素均为带入组分,其中,中稀土较轻稀土和重稀土的活动性更强;其它微量元素中,带入序列由强到弱为:Cr →Ta →Sn →Th ,迁出序列由强至弱依次为:U →Sb →Ni →Sr →Ba →Rb →Co →W;成矿元素Cu 和Ag 为带入组分,其中Cu 的带入量最大,质量迁移量高达1200 %。本文还得出两点具普适性认识: ①稀土元素较其它微量元素对体系条件的变化更为敏感,且往往表现出明显的规律性变化,能更好地示踪地质地球化学过程。②不同元素在不同体系中的行为特征差异极大,仅凭经验判定某一元素为不活动元素往往不可靠。因此,在开展质量平衡研究时,首先采用适当方法确认体系的不活动元素是一项不可或缺的前提工作。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

以五龙金矿为例,在同一剖面上采集了不同成矿阶段的含金石英脉和近矿蚀变岩样品,.根据矿物流体包裹体和蚀变岩成分地的测定结果,系统地讨论了不同成矿阶段流体包裹体成(K^+、Na^+、Ca^+、CO2等)和不同蚀变岩成分(K2O、Na2O、CaO1、MgO、CO2等)的变化规律,结果表明,从第二成矿阶段到第四成矿阶段,流体中的Na^+、Ca^+、Mg^+含量有明显的升高的趋势,K^+ 含量降低,蚀变岩中,K2O由远离矿体的原岩到靠近矿体的蚀变岩其含量增加,而Na2O、CaO、MgO逐渐降低,这种流体包裹体和蚀变岩中的某些相应成分的变化特征,应该是流体-岩石相互作用的结果。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

云南鸡街碱性超基性岩杂岩体的主体岩石为岩浆结晶分异作用的产物,形成顺序为霞霓钠辉岩→霓霞岩→磷霞岩。在杂岩体的霓霞岩中发现了1粒具分带现象的橄榄石,从中心到边缘,SiO2、MgO和NiO逐渐降低,而FeO和MnO逐渐升高。MgO与SiO2和NiO之间呈正相关关系,与FeO和MnO之间呈负相关关系,中心的Fo值(最高为86.91)略高于霞霓钠辉岩中斑晶橄榄石(Fo值:85.66~86.02),而边缘的Fo值(最低为73.82)与霓霞岩中无分带现象橄榄石(Fo值:72.18~74.72)相近。各种证据表明,发现的具分带现象橄榄石可能不是霓霞岩熔体结晶分异作用的产物,而可能是霓霞岩熔体捕获的Fo值相对较高(高于霓霞岩橄榄石的Fo值)的橄榄石晶体内部MgO和FeO等成分扩散作用的结果。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

对滇西上芒岗红色粘土型金矿的主元素,微量元素和稀土元素地球化学特征进行了详细的研究。结果表明,主元素Al2O3,Fe2O3和K2O在红色粘土剖面中共迁移同沉淀,SiO2的变化却与它们相反,这揭示了上芒岗红色粘土型金矿的红色粘土层除了残积带红土化程度高外,总体上SiO2含量高,去硅作用不完全,红土化程度低;与地层,矿化蚀变岩的对比分析结果表明,红色粘土是在加勐嘎组泥岩基础上经红土化作用形成的,红色粘土的微量元素表现为Au,Hg,As,Sb,Cu,Pb,Zn和Mo等元素的共生,在红土化好的残积带明显富集;红色粘土的大离子元素分布模式与矿化蚀变岩和嘎组的相似,红色粘土的稀土分布模式与矿化蚀变岩和地层的相似,表现为轻稀土富集的右倾型平缓曲线,稀土元素分蚀明显的地方金富集,以上分析揭示,此金矿的成矿物质主要来自矿化蚀变岩,红色粘土主要来源于勐嘎组和矿化蚀变岩.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

本论文通过对贵州贵阳花溪杨中喀斯特山区的植被调查与土壤样品分析, 研究土壤-植被中Ca、Mg、 K、P分布特征、变化规律及其影响因素,并在此基础上尝试Ca同位素的预处理研究,以期为喀斯特地区土壤-植被中Ca、Mg、 K、P(尤其是Ca)的生物地球化学循环研究奠定基础,同时为植被演替、物质循环研究和退耕还林还草的人工恢复提供植物自身的营养依据。本次研究取得如下认识: 1.受石灰岩母岩控制,土壤样品元素含量的特征为:CaO>MgO>K2O> P2O5。同一元素沿海拔变化有一定的相关性,并且相关性随元素的不同存在差异:随海拔高度的增加CaO含量有升高的趋势,而MgO 、K2O、Na2O含量都有所降低。表层土壤中K2O-Na2O含量正相关变化,CaO-K2O含量负相关变化。并且从土壤表层到底层在剖面-1中随深度增加,CaO、MgO、K2O含量升高,而P2O5的含量则有上升的趋势。土壤中元素的上述分布特征主要与石灰岩的风化成土作用过程中不同分化程度土壤Ca的淋失和来自高处的富钙雨水输入有关。 2.喀斯特生态环境富钙的这一特点对喀斯特灌丛植物的种类成分和营养元素含量有很大影响。地貌部位、海拔高度对植物Ca、Mg 、K、P含量也有不同程度的影响。植物Ca、Mg 、K、P含量由高到低依次为:Ca > K > Mg >P。苔藓与其它植物比较, Ca、Mg、 K、P的含量都小于其它三类较高等的植物,这一现象与其自身的生物学特性有关:苔藓植物组织结构简单,不具备发达的输导组织,不具备真正的根系,不利于从土壤等基质中吸收营养。在、灌草、灌木、藤本三类植物营养元素之间Ca –P含量具有负相关变化,Mg –P含量具有正相关变化;在所分析的植物种,P- K含量变化呈正相关,并且植物叶片Ca/K比值随着P含量的增加而显著地以指数形式减小。这是因为植物体内的K和P对于Ca来说起着平衡离子(counter ion)的作用。 3. 生境中基岩裸露和土体浅薄的特点,极大地制约了喀斯特灌丛的发育,喀斯特生境的富含钙的特点对喀斯特灌丛植物的种类成分和元素含量有很大的影响。但是杨中灌丛群落植物Ca、Mg、K、P含量和对应土壤CaO、MgO、K2O和P2O5含量相关性不明显。植物Ca、Mg、K、P元素虽主要来源于土壤,但因其含量受元素地球化学性质、植物种类、土壤元素对植物有效态的含量等因素的制约,而使植物元素含量和土壤元素的含量没有明显的相关性. 4.从Ca同位素的预处理研究来看,离子交换分离法对去除样品中的杂质效果较好。在以后测定过程中,有利于增强离子流稳定性和强度, 提高测量精度和准确度,与沉淀法相比较,此法适宜作为钙同位素样品的前处理方法。 关键词: 喀斯特 石灰土-灌丛系统 Ca、Mg、K、P含量分布 钙同位素 环境地球化学