天然褐铁矿的光电化学响应及对嗜酸性氧化亚铁硫杆菌生长的影响

通过对比实验研究了天然褐铁矿对嗜酸性氧化亚铁硫杆菌(A.f.)生长的影响.利用X射线衍射分析(XRD)确定实验中所用天然褐铁矿样品的主要物相为针铁矿和赤铁矿,紫外-可见漫反射光谱(UV-Vis DRS)和不同光照条件下的时间电流曲线表明天然褐铁矿在可见光下具有良好的光电化学响应.采用"H"型装置进行双室体系反应,设置了3组对比实验,结果显示A.f.在有光催化电子传入情况下生长较好,在96 h内细胞浓度增加了12倍,3组实验中Fe2+浓度的变化规律与A.f.的生长趋势相对应.由此揭示了天然褐铁矿促进A.f.生长的机制为:在光照作用下天然褐铁矿能产生光生电子-空穴对,光生空穴被电子供体(抗坏血酸)捕获,分离出的光生电子传入阴极室能够将Fe3+还原为Fe2+,实现Fe2+的电化学再生,提供充足的电子能量来源,促进细菌生长.     

褐铁矿和白云石对垃圾渗滤液厌氧消化增强作用的初步研究

垃圾渗滤液治理一直是城市生活垃圾卫生填埋场的难题。能否利用矿物-微生物交互作用提高垃圾渗滤液有机污染物厌氧转化的效率是值得研究的问题。本文设置4组厌氧生物反应器(分别为只添加褐铁矿或者白云石、同时添加褐铁矿和白云石以及不添加矿物的空白组),考察添加褐铁矿、白云石对垃圾渗滤液厌氧消化的影响。实验结果表明,厌氧生化反应12 d时,添加了褐铁矿和白云石的反应器中COD去除率均达到80%以上,而空白对照组COD去除率仅为50%;4组反应器中溶液pH值变化表明,矿物的存在提高了溶液的pH值0.5左右;4组反应器中氨氮含量变化不大,也没有表现出明显差异。研究认为褐铁矿或白云石矿物在垃圾渗滤液中有机物的厌氧消化过程中起到了重要促进作用。研究结果为提高垃圾渗滤液厌氧处理效率提供了一个可供参考的方法。     

Kinetics of illite dehydroxylation

Illite is a dioctahedral K-deficient mica with an interlayer cation content of 0.6–0.85 atoms per formula unit. 1M and 2M₁ are the illite polytypes more abundant in nature. Because illite is one of the major component of clays used for the production of traditional ceramics, the understanding of its high temperature transformations is of paramount importance for the knowledge of the structural and microstructural properties of fired ceramic products. To our knowledge, the study of the illite dehydroxylation kinetics has not been attempted to date. Hence, this work presents the investigation of the reaction mechanism of dehydroxylation of illite for the first time. The natural sample investigated in this study is a 1M-polytype from Hungary. Several classical methods of kinetic analysis were used (isoconversional method, Avrami method, direct fit with kinetic expressions, and others) to achieve a complete picture of the dehydroxylation mechanism. The proposed model for the dehydroxylation of illite is a multi-step reaction sequence with (1) condensation of the water molecule in the octahedral layer; (2) one-dimensional diffusion of the water molecules through the tetrahedral ring (rate limiting step of the reaction); (3) two-dimensional diffusion of the water molecules through the interlayer region (rate limiting step of the reaction).     

天然褐铁矿处理含Hg（Ⅱ）废水的实验研究

利用水合金属氧化物和氢氧化物矿物表面重金属离子发生吸附作用的原理，进行了天然褐铁矿处理含Hg(Ⅱ)废水的实验。结果表明：试样用量、粒径、废水浓度、pH值、离子强度、反应时间、振荡器转速等因素对Hg(Ⅱ)的吸附率有一定的影响，其中pH值的影响最大；Hg(Ⅱ)在天然褐铁矿上的吸附等温曲线不同于Langmuir和Fre-undlich等温线，而为台阶型，符合分级离子／配位子交换等温曲线。     

海南儋州南江褐铁矿矿床地质特征及控矿因素分析

南江褐铁矿产于下石炭统南好组中,矿体呈脉状、透镜状产出,规模较大、品位很高、质量较好.矿区内发育3组断裂,NNE向断裂控制了矿体的产出,并为矿液运移提供通道;兰洋岩体提供了成矿热液和物质来源.从矿床地质特征分析,为先成的热液型铁矿受古地理条件和气候影响,风化淋滤成褐铁矿,在地表出露为铁帽.预测其找矿前景较好.     

铜陵新桥矿田褐铁矿矿物组成及成因

褐铁矿是铁帽型金矿和铁矿的重要矿产类型,但目前对其从矿物学的微观角度研究较少。本文采用粉晶X射线衍射(XRD)以及场发射扫描电镜(SEM)矿物学研究手段,对铜陵矿集区新桥矿田褐铁矿的矿物组成、微结构进行研究。根据矿物组成及微结构将新桥褐铁矿分为两种成因类型:Ⅰ型褐铁矿,该类型褐铁矿主要起源于黄铁矿矿石,矿石多具蜂窝状构造。主要组成矿物为针铁矿,次要矿物为赤铁矿,含有少量石英,针铁矿晶体长度一般介于500 nm~2μm,长度/半径比值(长径比)较大;Ⅱ型褐铁矿,由原生菱铁矿矿石风化而成,矿石多具肾状构造。矿物组成主要为针铁矿,其次为赤铁矿、锰氧化物和伊利石等粘土矿物,针铁矿晶体长度一般小于500 nm,具有较小的长径比。褐铁矿矿物学和微结构不仅可以初步确定原生矿物和矿石类型,而且对寻找铁帽金矿床也具有重要指示意义。     

热处理褐铁矿去除水中的Mn2+

本文利用褐铁矿中针铁矿经热脱水相变获得以纳米晶赤铁矿为主要物相的纳米-微米多级孔结构材料,并用于模拟净化富Mn~(2+)地下水。同时考察了热处理温度、初始pH值、初始Mn~(2+)浓度、吸附反应时间等对材料去除溶液中Mn~(2+)的影响。XRD、TEM、BET表征结果表明,300℃热处理产物中赤铁矿孔径最小为2.7 nm,比表面积最大达到107.4 m~2/g。吸附实验结果表明,在pH值5~10的范围内,p H值对煅烧褐铁矿颗粒对Mn~(2+)去除效果影响较小;材料在贫氧条件下对水中低浓度Mn~(2+)的最大吸附量为6.45 mg/g;吸附动力学符合准二级动力学模型;褐铁矿热处理形成的纳米晶赤铁矿对Mn~(2+)具有吸附和催化氧化作用,其中的杂质锰氧化物对Mn~(2+)的吸附和催化氧化具有增强作用。     

原位磁化X射线粉末衍射法测还原铁粉的微观磁致伸缩系数

首次报导X射线粉末衍射法测量铁粉晶胞的磁致伸缩系数。还原铁粉样品原位磁化后 ,铁立方晶胞产生磁致伸缩效应 ,晶胞参数的变化引起衍射峰位置和晶面间距的变化。实验测得铁晶胞λ1 0 0 为 3 .3 3× 10 - 4,此结果表明铁晶胞的微观磁致伸缩系数比棒状、薄膜或粉末压片的系数大约 16倍。对此现象进行了合理的理论解释 ,指出大块材料中的粉末多晶之间具有较大的空隙 ,从而使得宏观磁致伸缩系数变小     

NaAlSiO4高温高压相变及产物的X射线衍射研究

采用多顶砧静态高温高压实验装置和X射线衍射分析方法研究了合成霞石NaAlSiO4在压力为22．25GPa,温度为1200—2000℃条件下的相变及其产物的晶体学特征,结合前人研究成果探讨了NaAlSiO4的高温高压相变过程和CaFe2O4型NaAlSiO4的稳定性及其地质意义。结果表明,合成霞石NaAlSi04在23GPa,1500℃时就可以完全转变为CaFe2O4型NaAlSiO4。结合前人的研究成果可以认为：CaFe2O4型NaAlSiO4在地幔深部可以稳定地存在,并对Na、Al在深部的赋存具有重要意义;随着温度压力条件的变化,CaFe2O4型NaAlSiO4的晶体学参数(晶格常数、晶胞体积和计算密度)发生变化,但变化的幅度不大。     

High temperature dehydroxylation of muscovite-2M1: a kinetic study by in situ XRPD

Muscovite-2M₁ shows a major phase transition at about 800°C, which is generally attributed in the literature to the structural dehydroxylation process, although a number of structural models have been proposed for the dehydroxylated phase, and different transformation mechanisms have also been put forward. The observed first order transformation involves an increase in the cell volume, and it is not clear to date how the cell expansion is related to the loss of hydroxyl groups. The phase change has been re-investigated here by in situ high temperature powder diffraction, both in non-isothermal and isothermal modes, to combine for the first time the structural and the kinetic interpretation of the transformation. The results unequivocally confirm that the reaction taking place in the temperature range 700–1000°C is truly a dehydroxylation process, involving the nucleation and growth of the high temperature dehydroxylated phase, having Al in 5-fold coordination. Structural simulations of the basal peaks of the powder diffraction patterns indicate that the model originally proposed by Udagawa et al. (1974) for the dehydroxylated phase correctly describes the high temperature phase. The kinetic analysis of the isothermal data using an Avrami-type model yields values for the reaction order compatible with a reaction mechanism limited by a monodimensional diffusion step. Apparent activation energy of the process in vacuum is about 251 kJ/mol. Experiments carried out at temperatures much higher than the onset temperature of the reaction show that the dehydroxylation reaction overlaps with the reaction of formation of mullite, the final product in the reaction pathway. Received: 24 April 1998 / Revised, accepted: 12 October 1998     

322矿田铀矿床原地破碎浸出地质技术评估

本文从原地破碎浸出法采矿要求出发，对322铀矿田碎裂蚀变花岗岩型铀矿床（点）的地质构造、岩／矿石物质成分、矿石结构、铀的赋存形式、岩／矿石物理力学参数、矿体形态、产状、规模及矿床水文地质条件进行了研究；通过原地爆破筑堆试验及一系列铀矿的柱浸工艺试验，获得了大量原地破碎浸出参数；运用原地破碎浸出法适用性评价模型对其进行了评价，认为该矿田碎裂蚀变花岗岩型铀矿床适宜采用原地破碎浸出法开采。     

The effect of composition and cation ordering on the compressibility of columbites up to 7 GPa

The unit-cell parameters of two columbite samples along the (Fe,Mn)Nb₂O₆ solid solution were measured by means of high-pressure single-crystal X-ray diffraction up to pressures of 7 GPa. The compressional behaviour of these minerals was studied as a function of composition and degree of order. The P–V data of all the samples were fitted with a third-order Birch–Murnaghan equation of state. For the two samples with different compositions but identical degree of order the substitution of Mn for Fe causes a decrease of the bulk modulus K _T0, from 153(1) to 146(1) GPa, without any effect on the pressure first derivative K′. For the two samples with the same composition, cation ordering causes an increase of the bulk modulus from 149(1) to 153(1) GPa and of the pressure first derivative from 4.1(2) to 4.8(3). The compressional behaviour is anisotropic with a linear axial compressibility scheme β _b > β _c ≥ β _a for all samples, regardless of composition and degree of order. Such anisotropy increases sligthly with increasing Mn content.     

Kinetic study of the dehydroxylation of chrysotile asbestos with temperature by in situ XRPD

 The kinetics of the dehydroxylation of chrysotile was followed in situ at high temperature using real-time conventional and synchrotron powder diffraction (XRPD). This is the first time kinetics parameters have been calculated for the dehydroxylation of chrysotile. The value of the order of the reaction mechanism calculated using the Avrami model indicates that the rate-limiting step of the reaction is a one-dimensional diffusion with an instantaneous nucleation or a deceleratory rate of nucleation of the reaction product. Hence, the rate-limiting step is the one-dimensional diffusion of the water molecules formed in the interlayer region by direct condensation of two hydrogen atoms and an oxygen atom. The calculated apparent activation energy of the reaction in the temperature range 620–750 °C is 184 kJ mol⁻¹. The diffusion path is along the axis of the fibrils forming the fibers. The amorphous or short-range ordered dehydroxylate of chrysotile is extremely unstable because forsterite readily nucleates in the Mg-rich regions. Moreover, it is less stable than the dehydroxylate of kaolinite, the so-called metakaolinite, which forms mullite at about 950 °C. This difference is interpreted in terms of the different nature of the two ions Mg²⁺ and Al³⁺ and their function as glass modifier and glass-forming ion, respectively. Received: 10 April 2002 / Accepted: 7 January 2003 Acknowledgements This work is part of a COFIN project (04 Scienze della Terra, NR 17, 2000) supported by MURST. Dr Dapiaggi is kindly acknowledged for help during the data collection at the Dipartimento di Scienze della Terra, University of Milan.     

某蛇纹石型红土镍矿常压硫酸溶解浸出实验研究

随着高品位硫化镍资源的日益减少及社会发展对镍需求量的日益增加,低品位红土镍矿的开发利用受到人们的日益关注。本文在对某蛇纹石型红土镍矿详细的矿物学研究基础上,进行了常压硫酸溶解浸出实验研究,获得硫酸浓度1 mol/L、液固比10、浸出反应温度70℃以上、反应时间6 h左右、磨矿细度65%(76μm以下含量)左右的最佳硫酸溶解浸出实验条件;该实验条件下,红土镍矿中Ni、Fe、Mg的浸出率分别为94.4%、72.1%和88.64%。本研究可为该类型红土镍矿的经济回收利用提供科学依据。     

伟晶花岗岩型铀矿石堆浸工艺研究与应用

介绍某低品位伟晶花岗岩型铀矿石矿物特性。研究在混合氧化剂存在条件下的这种难浸矿石的堆浸工艺。500 t半工业结果表明：试验解决了该类型矿石堆浸工艺,达到了工业生产要求的技术指标。     

Calibration of the anchizone: a critical comparison of illite 'crystallinity'scales used for definition

Instrumental settings for determination of illite/muscovite 'crystallinity'(half-height width of the 10-Å X-ray diffraction peak) and the limits of the anchimetamorphic zone adopted by various authors fall into several groups.
The variation in the limiting peak widths between the authors that have adopted Kubler's Neuchâtel boundary values of 0.42° and 0.25°Δ2θ can be interpreted in terms of variation in the instrumental settings. The choice of time constants higher than those given by the formula causes peak broadening; this effect is particularly marked at high scan rates. The peak broadening is by constant increments that are virtually independent of the absolute peak width.
The differences between the Kubler (Neuchâtel)-derived limiting values and some other scales are appreciably greater than can be accounted for by these differences in instrumental settings: many of these scales are not equivalent. In particular, the limits adopted by Dunoyer de Segonzac (1969) and subsequent workers at Strasbourg are too broad; their anchizone represents a range of grades of metamorphism lower than that of Kubler, widely overlapping the latter's 'diagenetic'zone. Those adopted by some other, mainly French, authors are too narrow.
The limits of the anchizone should be calibrated by inter-laboratory standards, and the instrumental settings should be specified in full.     

Kinetics of leaching of oxidized and reduced ilmenite in dilute hydrochloric acid solutions

Ilmenite separated from beach sands of Bangladesh was oxidized for 1 h at 950 °C and then reduced in charcoal for 4 h at 1050 °C. This was followed by leaching in 5% to 15% hydrochloric acid solution in temperature range of 30 to 75 °C for periods of up to 2 h. The results were compared with those obtained by leaching of ilmenite reduced without oxidizing. Oxidation prior to reduction of the ilmenite was found to increase both the extent and the rate of leaching. The residual iron contents after leaching were also found to be lower than that obtained for non-oxidized samples. The kinetic data of leaching of ilmenite reduced after oxidation was found to follow first order reaction model, i.e., G(α) = − ln(1 − α) up to an α value of 0.5 (i.e. up to 50% reduction) and then changed to spherical model, i.e., G(α) = [1 − (1 − α)]³. On the other hand, leaching of ilmenite reduced without oxidizing was found to follow the Ginstling-Brounshtein reaction, i.e., G(α) = 1 − (2/3)α − (1 − α)^2/3 throughout the leaching process. Oxidation of ilmenite prior to reduction was also found to have decreased the activation energy of leaching from 43 kJ/mol, found for samples leached after reduction without oxidizing, to 30 kJ/mol.     

Development and Implementation of Disaster Reduction Technology in Taiwan

In order to improve the efficiency of disaster reduction, the government of Taiwan has taken a number of initiatives in the development of disaster reduction technology since 1982, including the 1st, 2nd and 3rd 5-year plans for hazards prevention research, and the National Science and Technology Program for Hazards Mitigation (NAPHM). In this article, the contents and achievements of the 5-year plans and the NAPHM are briefly reviewed. On the one hand, the 5-year plans have produced meaningful research results; on the other hand, the NAPHM has provided a mechanism for integrating and translating the research results into technologies that can be implemented. The NAPHM was transformed in 2003 into the National Science and Technology Center for Disaster Reduction (NCDR) to further enhance the development and implementation of disaster technology. The mission and major future works of the NCDR are discussed.     

X射线粉晶衍射仪测定萤石晶胞参数

利用X射线粉晶衍射仪对纯萤石矿物进行全谱扫描,在确定萤石矿物衍射5强峰基础上,准确标出萤石5强峰相应的d值,按2θ角值由大到小的顺序排成纵行,计算出不同d值的1/d2值,用1/d2值最小一条线的值去除其余各条线的1/d2值,得出的数值D仍依次排列;据D值小数部分是0.36或0.68数值,推断实验所测萤石低角度的第一条线是{111}网面衍射产生的,其相应的h2+k2+l2值为3,以第一条线h2+k2+l2值3分别乘以其余各条线的D值,得出的数据h2+k2+l2值仍依次排列,分别为8.04,11.04,16.08和19.08,由于测量的误差,舍去小数点后数据,保留整数位,即可得到相应的h2+k2+l2值3、8、11、16和19,据h2+k2+l2值查出相应网面指数为{111}、{220}、{311}、{400}和{331},根据晶胞参数公式:a=d(hkl)(h2+k2+l2)1/2计算出萤石晶胞参数值为0.546 nm。     

新疆尉犁水黑云母:定向X射线衍射研究

用定向Ｘ射线衍射方法研究了产自新疆尉犁的两个水黑云母样品（ｘｊ－１和ｘｊ－２）。ｘｊ－１含有水黑云母和蛭石两种矿物,ｘｊ－２含有水黑云母和金云母两种矿物。两个样品中水黑云母的ｄ００１有所不同,它们的衍射蜂形和衍射强度与完全规则的水黑云母有一定的差异。根据图解法研究结果表明,在ｘｊ－１中观察到的水黑云母衍射数据实际是大量水黑云母层与少量蛭石层不规则间层的结果,而在ｘｊ－２中观察到的水黑云母衍射数据实