我国与海西期A型花岗岩有关钖矿床的新发现

本文介绍我国1987年新发现一处与海西期A型花岗岩有关的独立锡矿床——萨惹什克锡矿。其岩体岩石学、矿物学及地球化学特征与国内外A型花岗岩特征进行了类比,指出其岩石学某些特征不仅比国际上著名的尼日利亚A型花岗岩还要典型,而且锡矿床地质特征特别,明显不同于国内著名的一些锡矿床,可作为我国与非造山花岗岩伴生锡矿床之代表,该锡矿且形成于海西期,在国内属首次发现,在世界上亦罕见,将成为我国一新的锡矿类型。     

浅谈个旧地区锡矿石“溶锡”问题

个旧地区开采的锡矿石无论是氧化矿或硫化矿均以锡石为主体。近二十年来,不少关于个旧锡矿的开发利用研究报告中都提到“酸溶锡”的问题,实为选矿工作者很感辣手的问题之一。锡石被公认为化学性质相当稳定的矿物,现今仍有不少人对于锡石不溶于无机酸的论点深信无疑。在很长一段时期内,一些单位由于传统的认识或生产部门的要求等原因,只分析锡石品位作为锡矿地质储量及生产计量。采用盐酸及硝酸(或氯酸钾或再加氟化物)加热处理锡矿石试样,在不溶渣中测锡。既使矿石中的锡完全以锡石形态存在,这样测得的结果是否能代表锡的含量也是值得怀疑的。我们曾于七十年代初对个旧矿区几个采选厂的主要是氧化矿砂锡矿试样(原矿及尾矿)进行普查,发现用盐酸及硝酸加热处理试样后的滤液中,皆存在0.00x—0.03%的锡,这对于近期矿山采矿锡品位不断下降的原矿来说,可以说是相当大的数字。“酸溶锡”占原矿含全锡的百分比,相对于氧化矿占0.0x—4%,相对于硫化矿占8—10%,而尾矿中“酸溶锡”     

宁镇地区燕山期矽卡岩矿床成矿系统稀土元素地球化学研究

通过宁镇地区燕山期矽卡岩矿床成矿系统的稀土元素特征研究,了解了矽卡岩矿床成矿系统的稀土元素地球化学演化规律特征及其制约机制,为矽卡岩型多金属矿床成矿规律及成矿预测研究提供新的地质地球化学信息依据。研究表明,矽卡岩矿床成矿系统稀土演化规律为:矽卡岩期,干矽卡岩阶段到湿矽卡岩阶段稀土组分含量增加;矽卡岩期晚期到热液期早期降低;热液期,汽成热液氧化物阶段到高中温硫化物阶段增加,到中低温硫化物阶段降低。演化规律主要是受自身富集稀土元素的强度、流体含矿性、运移分配及成矿的物理化学条件的影响。矽卡岩矿床成矿系统主要矽卡岩化的发育及其分带性所具有成矿专属性等特点,都为进一步寻找矽卡岩型多金属矿床提供新的地质地球化学信息。     

马坑铁矿——一个海相火山热液-沉积型矿床

本文通过对马坑铁矿床产出地质环境、产状特征、原生矿石类型及其结构构造的研究,阐明了该矿床属同生沉积成因,矽卡岩只是成矿后的热液迭加。并根据地质测温、矿石物质组分及成矿过程锰、铁分离等地球化学特征,论证了马坑铁矿为火山热液-沉积矿床。稳定同位素研究证明了成矿热流体为“岩浆水”与海水的混合。     

某锡矿区锡物相分析方法的研究——硫化物相、水锡石相、硅酸盐相、锡石相的测定

我国在50年代就开展了锡的物相分析,所用的溶剂与苏联的分析方法相同。此法沿用了相当长一段时期,但近年来在工作实践中发现除黝锡矿、辉锑锡铅矿、锡石等矿物存在外,还存在有许多含锡的矿物如含锡的硅酸盐类矿物,含锡的硫化矿物(如磁黄铁矿、黄铁矿等),含锡的氧化矿物(如磁铁矿),以及水锡石类矿物等。如果仍按原流程进行物相分析,难溶硅酸盐类矿物中的锡则与锡石一起计量,而易溶硅     

复合挡土结构在稀土矿山滑坡防治中的应用研究

风化壳离子吸附型稀土矿床,是中国赣南地区所特有的一种矿床,在开采工艺上主要采用国家推广的第三代原地浸矿法。以江西省龙南县乡标稀土矿山滑坡为例,在对研究区滑坡进行野外实地调查,并结合该稀土矿开采工艺流程、滑坡区地质环境条件,分析总结了滑坡形成机制,主要表现在两方面:岩土性质、结构、坡型、坡度和高差等内因的影响;降雨、地表径流、地下水和浸矿时的注液加压等外部因素的影响。最后进行了"树根桩+锚杆"组合的复合挡土结构设计,以防治离子型稀土矿山滑坡的发生,最大限度地保证了采场工作人员的生命安全,减少了经济损失,提高了开采效益。     

中国沉积-改造铅锌矿床

本文主要阐述了我国沉积-改造型层控铅锌矿床的地质特征,铅、硫、氢、氧稳定同位素的组成,改造热液的物理化学性质及其来源,Pb、Zn元素的活化迁移和沉淀的实验研究,矿床的成矿规律等。认为矿床的形成首先是成矿物质与含矿岩系同生沉积,又受后期地质作用影响而被改造及进一步富集成矿。整个成矿过程与岩浆活动没有明显联系。     

赣南离子吸附型稀土矿床成矿特征概述

赣南是我国离子型稀土资源的主产区之一,其成矿母岩分布广,成矿条件优越,稀土配分类型多样。本文从成矿背景和矿床分布规律,成矿母岩和矿体赋存特征,以及矿石中稀土的赋存状态和配分类型等方面较为详细地总结了赣南稀土矿床成矿地质特征。     

重(三硝基乙基)乙二硝胺的热分解 Ⅱ. 晶体性质与热分解动力学参量的关系

我们曾发现,重(三硝基乙基)乙二硝胺(BTNE)晶体热分解反应速度常数k的数值与该晶体重结晶条件有关系,而不同重结晶过程有可能给出性质各异的品体。在本文中,作者们利用差示扫描量热(DSC)、X-光多晶衍射、电子扫描显微镜(SEM)技术研究了工作[1]中提到的十种BTNE晶体,BTNE的单晶(BT-M)和未经任何重结品处理的实验室合成的BTNE粗品(BT-U)的晶体性质。利用DSC和X-光多晶衍射技术研究了BTNE晶体的晶型。同一晶体的不同晶型具有各自的X-光衍射图,而不同晶型间的转换可在DSC曲线上表现出存在有相应的吸热峰。工作[1]中给出的DSC曲线表明,     

浅谈腾冲地块与稀土矿有关的岩浆岩成矿专属性

目前,腾冲地块已初显国家级稀土矿战略后备基地雏形,但整体研究程度仍偏低,稀土矿床的成矿规律、成矿模式等方面的研究趋于空白。在前人研究的基础上,结合近年稀土矿勘查工作成果,通过研究腾冲地块不同时代、不同岩性的岩浆岩与稀土矿产出关系,取得以下认识:腾冲地块稀土矿床(点)成矿母岩时代有三叠纪(印支期)、白垩纪(燕山期)、古近纪和第四纪(喜马拉雅期),以古近纪(喜马拉雅期)为主;岩石类型有二长花岗岩、花岗斑岩、钾长花岗岩、英云闪长岩等,以二长花岗岩为主;成矿母岩都具有高硅(68%～78%)、富铝(12%～15%)、富碱(W_B(K_2O+Na_2O)值7.5%～10.6%,多数大于8%)、富钾(钾大于钠)特征,且稀土元素丰度较高;以轻稀土矿为主,仅有个别重稀土矿。腾冲地块发育有轻稀土矿与重稀土矿成矿母岩,具有得天独厚的稀土成矿条件,仍具有较大的找矿潜力。在今后地质工作中,应提高重视加强对稀土矿找矿勘查工作,尤其是古近纪岩体分布区、重稀土矿成矿母岩分布区,如陇川—盈江、新岐、古永地区。同时,对已发现的锡矿、铁矿等矿床,综合评价其花岗岩风化壳型稀土矿。     

The Influence of Sodium Dodecyl Sulfate on the Surface Free Energy of Cassiterite

Measurements of contact angles for water, glycerol, formamide, diiodomethane, and bromoform on a cassiterite surface covered with sodium dodecyl sulfate (SDS) film were made. The samples of cassiterite were prepared in different ways for the measurements. Using the contact angle values, the Lifshitz-van der Waals and acid-base components of cassiterite/SDS film surface free energy were determined and compared with those for a "bare" cassiterite surface. It was found that the contact angle and the components of the surface free energy depend on the pH and concentration of the SDS solution from which the adsorption layer was formed. Also, the method of preparation of cassiterite plates influences these parameters. It was also found that the hydration of the cassiterite surface in the presence of a SDS film takes place and depends on the concentration of SDS, pH, and method of sample preparation, and strongly influences the surface free energy components of cassiterite.     

Comparison of cation adsorption by isostructural rutile and cassiterite

Macroscopic net proton charging curves for powdered rutile and cassiterite specimens with the (110) crystal face predominant, as a function of pH in RbCl and NaCl solutions, trace SrCl(2) in NaCl, and trace ZnCl(2) in NaCl and Na Triflate solutions, are compared to corresponding molecular-level information obtained from static DFT optimizations and classical MD simulations, as well as synchrotron X-ray methods. The similarities and differences in the macroscopic charging behavior of rutile and cassiterite largely reflect the cation binding modes observed at the molecular level. Cation adsorption is primarily inner-sphere on both isostructural (110) surfaces, despite predictions that outer-sphere binding should predominate on low bulk dielectric constant oxides such as cassiterite (ε(bulk) ≈ 11). Inner-sphere adsorption is also significant for Rb(+) and Na(+) on neutral surfaces, whereas Cl(-) binding is predominately outer-sphere. As negative surface charge increases, relatively more Rb(+), Na(+), and especially Sr(2+) are bound in highly desolvated tetradentate fashion on the rutile (110) surface, largely accounting for enhanced negative charge development relative to cassiterite. Charging curves in the presence of Zn(2+) are very steep but similar for both oxides, reflective of Zn(2+) hydrolysis (and accompanying proton release) during the adsorption process, and the similar binding modes for ZnOH(+) on both surfaces. These results suggest that differences in cation adsorption between high and low bulk dielectric constant oxides are more subtly related to the relative degree of cation desolvation accompanying inner-sphere binding (i.e., more tetradentate binding on rutile), rather than distinct inner- and outer-sphere adsorption modes. Cation desolvation may be favored at the rutile (110) surface in part because inner-sphere water molecules are bound further from and less tightly than on the cassiterite (110) surface. Hence, their removal upon inner-sphere cation binding is relatively more favorable.     

Relationship between heat of immersion and surface Gibbs energy of fluorite and cassiterite

Calorimetric measurements were made of the heat of immersion in water of cassiterite that was either untreated or treated with 60% HNO₃. The heats of immersion of cassiterite and fluorite were also calculated theoretically from the surface Gibbs energy components, and compared with the heat of immersion measured for cassiterite and that taken from the literature for fluorite. The results of the measurements and calculation revealed that the heat of immersion depends on the degree of hydration of the surface of cassiterite and fluorite. It was also found that it is possible to predict the heats of immersion in water of cassiterite and fluorite from the Lifshitz-van der Waals and acid-base components of the surface Gibbs energy.     

Determination of tin, bismuth, antimony, indium, gallium and arsenic by solvent extraction cum atomic absorption spectrophotometry

A rapid atomic absorption spectrometric method for the determination of tin, antimony, bismuth, indium, gallium and arsenic in geological materials, steels and alloys is described. The samples are fused with sodium peroxide (for geological samples such as cassiterite and sulphides) or decomposed with sulphuric/hydrochloric acid mixture or by alkaline fusion (for silicates or bauxites) or by acid treatment (for steels, alloys and certain geological samples). The elements of interest are extracted as their iodides into methyl isobutyl ketone, stripped into aqueous solution by treatment with benzene, concentrated nitric acid and water, and determined by flame atomic-absorption spectrometry. Detailed study is made on stripping of the metals from organic phase as there no simple and rapid stripping procedures available. The method allows the determination of Sn, Sb, Bi and In down to 2 ppm and Ga down to 5 ppm. The relative standard deviations range up to 10% with an average of 2.5%. Apparent recoveries of these metals range from 90 to 110 with an average of 95% for Sb and 99% for others.     

Self-assembly of domain wall of molecular twist defects in polyethylene crystal

Two-dimensional structural defects in a polyethylene crystal (twist domain walls) are investigated by means of analytic treatment and molecular dynamics simulation. The formation of the domain wall as a result of relaxation of the crystal from different initial states is studied and parameters of this type of defects are calculated.     

Orientational order in binary mixtures of hard Gaussian overlap molecules

Based on a standard constant-pressure Monte Carlo molecular simulation, we have studied liquid crystal phases of binary mixtures of nonspherical molecules. The components of the mixtures are two types of hard Gaussian overlap (HGO) molecules. The first type of molecule has a small molecularelongation parameter (short HGO molecules) and cannot form stable liquid crystal phase in the bulk by themselves. The second type of molecule has a large elongation parameter (long HGO molecules) and can form a liquid crystal phase easily. In the mixtures, the short HGO molecules can form an orientationally ordered phase because the long HGO molecules form confining surfaces to induce the alignment of the short molecules. We also study the isotropic-nematic phase transition in different mixtures composed of short and long HGO molecules with different elongations and concentrations. The obtained result implies that small anisotropic molecules can show liquid crystal behavior.     

Fast determination of the tin content in cassiterite ores by photon activation method

Photon activation analysis has been success-fully applied to the fast and non-destructive analysis of tin in cassiterite ores based on the 159.7 keV gamma line of^123mSn produced in the¹²⁴Sn/γ, n/^123mSn reaction. In order to improve the accuracy of analytical results, corrections for self-absorption and pile-up effects were performed. Under typical conditions /15 μA electron beam current, 15 MeV bremsstrahlung energy, 5 min irradiation time and 10 min measurement/ the sensitivity of the analysis is 10 ppm. The proposed method can be used for routine analysis of tin in geological samples.     

Faster proton transfer dynamics of water on SnO2 compared to TiO2

Proton jump processes in the hydration layer on the iso-structural TiO(2) rutile (110) and SnO(2) cassiterite (110) surfaces were studied with density functional theory molecular dynamics. We find that the proton jump rate is more than three times faster on cassiterite compared with rutile. A local analysis based on the correlation between the stretching band of the O-H vibrations and the strength of H-bonds indicates that the faster proton jump activity on cassiterite is produced by a stronger H-bond formation between the surface and the hydration layer above the surface. The origin of the increased H-bond strength on cassiterite is a combined effect of stronger covalent bonding and stronger electrostatic interactions due to differences of its electronic structure. The bridging oxygens form the strongest H-bonds between the surface and the hydration layer. This higher proton jump rate is likely to affect reactivity and catalytic activity on the surface. A better understanding of its origins will enable methods to control these rates.     

MULTIPLE MELTING TRANSITIONS IN POLYURETHANE-UREA ELASTOMERS UNDER EXTENSION

Two melting transitions were observed in linear segmented polyurethane-urea elastomers underextension using thermal, mechanical and X-ray diffraction techniques, and the results are compared.These data indicate both strain-induced and temperature-induced crystallization in the stretchedclastomers, which may result from two different types of crystallites with different melting tempera-tures. These have been assigned as type 1 appearing around 60℃, and type 2 around 30℃. Thetype 1 crystallization can be induced by stretching at room temperature to large strain, and is mechani-cally reversible, but the type 2 crystallization is mainly induced by cooling below its crystallizationtemperature. These two crystalline structures are interchangeable under suitable conditions. Atelongations greater than 300%, the low temperature peak observed on fusion thermograms disappearsor combines with the high temperature peak. When the temperature of the sample is over the meltingpoint of the type 1 crystal, irreversible melting occurs and only the type 2 crystal develops on cooling.The results of stress-strain and stress hysteresis experiments at different temperatures indicate therelative importance of strain-induced and temperature-induced crystallization on the mechanicalproperties of these materials.     

锌片上多形貌ZnO微晶的水热合成及生长机理

本文采用水热法以锌片作为锌原料提供ZnO微晶生长的养料,在锌片上制备ZnO微晶。使用蒸馏水、NH3?H2O、NaOH和丁胺作为矿化剂,生长的水热环境呈碱性。实验表明,各种不同碱性矿化剂浓度、分子结构及矿化剂溶液的饱和蒸气压都显著地影响ZnO晶体的生长习性,使得样品的最终晶体形貌呈现不同的特点。研究中利用XRD中各晶面衍射强度值数据对晶体形貌特征进行推测,并以SEM进行形貌验证,同时探讨了以锌片为原料制备ZnO微晶的生长机理。