尾矿酸浸液制备氢氧化铁过程中施威特曼石的形成与转变

尾矿酸浸液在制备氢氧化铁的过程中,由于逐渐滴加碱液正好形成了pH值为2.8～3.8的高SO2-4、高Fe环境,因而生成了施威特曼石.施威特曼石是一种亚稳定矿物,随着时间的延长和体系状态改变,它可以转变为更稳定的针铁矿(氢氧化铁).考查了pH值、温度及时间对施威特曼石相转变的影响.结果表明,在60℃条件下,在pH值为12的碱溶液中转化36 h,施威特曼石可完全转变为Fe(OH)3.     

合成施威特曼石吸附Cu^2＋和Pb^2＋的实验研究

施威特曼石普遍存在于含大量SO42-的酸矿水中,其表面吸附的SO42-使得该矿物具有强吸附重金属离子的能力,可用于处理重金属离子污染。实验通过在不同浓度Cu2＋溶液中合成施威特曼石时发现,Cu2＋与施威特曼石的共沉淀量较低,FTIR分析表明Cu2＋与施威特曼石的羟基发生反应。开展施威特曼石吸附Pb2＋的实验,结果表明施威特曼石对Pb2＋的吸附符合Langmuir模型,施威特曼石吸附Cu2＋和Pb2＋后出现1545.4 cm-1和1435.0 cm-1（Cu2＋）两个吸收峰,可能是施威特曼石孔道表面形成了三元配合物。在241×10-6的初始浓度（与尾矿孔隙水的Pb2＋含量相近）下有61.4%的Pb2＋去除率,显示了较好的环境修复价值。     

金川镍矿尾矿砂中Ni和Cu赋存状态研究

金川镍矿浮选尾矿数量巨大,含有相当可观的有价金属,其中有价金属的回收受到越来越多的关注。金川老尾矿库尾矿砂中Ni和Cu赋存状态复杂,水溶性矿物态、可交换离子态、碳酸盐态、结晶度较差的Fe氧化物态、结晶度较好的Fe氧化物态、硫化物态和残渣态中都含有数量不等的有价金属Ni和Cu;尾矿砂风化作用释放的金属阳离子大多数在发生氧化的硫化物位置原位发生水解沉淀形成次生矿物,有价金属Ni和Cu在尾矿库中没有发生明显的富集。金川镍矿尾矿砂中Ni和Cu适于用化学酸溶浸出的方法进行二次回收。     

不同初始Fe(Ⅱ)浓度对施威特曼石生物合成的影响

施威特曼石(schwertmannite)已被证实是一种具特异性能的重(类)金属吸附新材料,生物方法合成的施威特曼石由于具备较好的表面吸附性能而受到更多关注。本文通过接种有嗜酸性氧化亚铁硫杆菌(Acidithiobacillusferrooxidans)的FeSO4-H2O矿物合成体系,研究了不同初始Fe2+浓度对Fe生物转化成施威特曼石效率的影响。结果表明,在Fe(Ⅱ)浓度(FeSO4.7H2O配制)设计为20、40、80和160 mmol/L,接种A.ferrooxidans菌密度达到6.0×107个/mL时,本实验条件下矿物重量y(g)与初始Fe2+浓度x(mmol/L)的关系为y(g)=0.036 67+0.008 520x-8.602.10-6x2;溶液TFe沉淀率y(%)与初始Fe2+浓度x(mmol/L)的关系为y(%)=39.68-0.221 0x+6.653.10-4x2。反应后期溶液中大量残留Fe3+在满足饱和指数SI>0的条件下不能析出矿物沉淀,进一步分析表明,Fe3+水解形成施威特曼石的可能机制是利用了Acidithiobacillus ferrooxidans菌氧化Fe2+释放的能量才得以实现,当Fe2+完全氧化不再供应能量时,Fe生物转化成施威特曼石的反应也达到了最大限度。     

Cl-/SO42-铁盐对含可溶性胞外多聚物Acidithiobacillus ferrooxidans溶液中铁矿物形成的影响

铁细菌胞外多聚物作用下聚集的铁可通过氧化或者沉淀作用使铁稳定或沉积,从而形成铁矿物。本文基于铁细菌胞外多聚物(extracellular polymeric substances,EPS)对铁矿物形成的调控作用,介绍了Cl-/SO_4~(2-)的Fe(Ⅲ)或Fe(Ⅱ)盐作用下,含可溶性EPS的氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans)溶液中铁矿物的形成,观察了溶液pH值变化及形成铁矿物的矿相与结构,并采用XRD、FTIR和FESEM对其进行表征。结果发现反应溶液中OH-离子可与Fe3+形成微米级"针垫"聚集球状或纳米级小球形施威特曼石和微米级"菱形"块状黄钾铁矾铁矿物沉淀。反应溶液中的可溶性EPS可调控和促进铁矿物的形成,但对Fe2+的氧化未产生影响;外源Fe盐可促进施威特曼石向黄钾铁矾转化。随着Cl-/SO_4~(2-)摩尔比例的增加(即Cl-含量的不断增加),两矿相间的转化明显受到抑制,且铁矿物颗粒之间的集聚作用明显减弱;反之,SO_4~(2-)含量升高时,有利于铁矿物间的转化和聚集球状颗粒形貌结构的形成。     

贵州松桃道坨锰矿含锰岩系地球化学特征 和沉积环境分析

道坨锰矿床是贵州锰矿整装勘查过程中新发现的全隐伏超大型锰矿床,其含锰岩系赋存于南华系大塘坡组第一段底部黑色页岩中,呈层状、似层状、透镜状产出。对含锰岩系主量及微量元素地球化学特征分析:其V/(V+Ni)、V/(V+Cr)、V/Cr、Ce/La值,及U、V、Ni、Mo等氧化还原敏感元素的富集程度显示其形成于缺氧环境。含锰岩系富集As、Mo、Ag、Sb,及Al/(Al+Fe+Mn)、(Fe+Mn)/Ti、Co/Zn值均显示热水沉积物特征,且在(Cu+Ni+Co)×10—Fe—Mn、Co/Zn—(Cu+Ni+Co)关系图解中,岩矿样品投影点均落在热水沉积区内,反映了热水作用对锰的富集和成矿影响甚重。此外,Al2O3/(Al2O3+Fe2O3)、Al/(Al+Fe)、Al/(A1+Fe+Mn)、(La/Ce)N值及(K2O+NaO2)—SiO2、La/Ce—Al2O3/(Al2O3+Fe2O3)图解指示含锰岩系形成于被动大陆边缘背景。     

广东大宝山铁龙AMD中赭色沉积物的含铁次生矿物研究

以广东大宝山铁龙酸性矿山废水(AMD)为研究对象,采集了7个采样点的赭色沉积物样品。利用X射线荧光光谱(XRF)、傅里叶变换红外光谱(FTIR)、X射线粉晶衍射(XRD)和场发射扫描电镜/能谱分析(FESEM/EDS),对AMD中赭色沉积物的矿物相及形貌进行鉴定。现场测定采样点水体物理化学参数(pH/Eh),探讨不同物理化学条件对含铁次生矿物相的影响。结果表明,大宝山铁龙AMD中赭色沉积物的含铁次生矿物主要有施威特曼石、黄钾铁矾、针铁矿、水铁矿等,此外沉积物中还含有七水铁矾、叶绿矾、四水白铁矾、针绿矾、纤铁矾、锡铁山石及羟铝矾等可溶性硫酸盐。施威特曼石具有带骨针棒状、海胆状形貌,针铁矿常呈针状及肾状集合体产出,黄钾铁矾呈六方板状,施威特曼石常可与黄钾铁矾或者针铁矿共生。赭色含铁次生矿物能在AMD较大范围的pH条件下存在,但倾向于Eh高的环境。当pH值增大时,施威特曼石有转变为针铁矿的趋势,并且针铁矿能保存施威特曼石的形貌特征。     

A.ferrooxidans培养过程中Al/Fe(摩尔比)对铁矿物形成产物的影响

主要研究了磷酸铝(Al PO4)的加入量对氧化亚铁硫杆菌HX3培养液中铁矿物形成的影响,并对相应沉淀产物进行了结构表征分析。结果表明,Al PO4的加入对细菌培养过程中Fe2+的氧化无明显影响,但可促进Fe3+的水解和初始铁矿物相的形成,也可加速黄钾铁矾的转化形成。Al/Fe(摩尔比)为0. 04～1的培养液中主要形成产物为施威特曼石和黄钾铁矾; Al/Fe为0. 4和1时另有磷酸铁矿形成。较高的Al/Fe比值和磷酸根含量有利于磷酸铁矿的形成。     

高钾铝硅酸盐物料中K2O含量的测定

为了精确测定分解反应过程中钾的挥发量,结合GB8574-2002,在样品高钾铝硅酸盐物料(钾长石、碳酸钾焙烧熟料,K2O含量大于15%)处理中采用聚环氧乙烷絮凝沉淀Si,新制Ca(OH)2溶液除去Mg2+、Fe2+、Fe3+、Mn2+等其他阳离子,加入碳酸铵稳定溶液pH值以除去Ca2+和Al3+.采用四苯硼钾重量法测定钾含量,测定结果与表样对照,相对误差在0.5%以内.实验表明:利用Ca(OH)2除杂,溶液pH值须控制在10～12;碳酸铵双水解反应后,溶液pH值须控制在7.35左右以除尽Ca2+和Al3+;低温(T＜473 K)蒸发溶液除去NH4+,消除了因生成四苯硼铵沉淀而带来的分析误差.结果表明该方法可以精确测定高钾铝硅酸盐物料的K2O含量,具有成本低、方便快捷、无需大型仪器之优点.     

湖南桃江响涛源锰矿地球化学特征及其成因意义

湖南响涛源锰矿位于湘中桃江成锰盆地。盆地内发育一组NNW向同沉积断裂,形成了一系列断陷槽,控制了沉积岩相的分布,其中黑色页岩、含锰灰岩、碳酸锰矿为成矿最佳的岩性组合。矿石的化学组分多样,Co、Ni、Pb、Mo和Ba等丰度较高,Co/Ni、SiO2/Al2O3、(Fe+Mn)/Ti、Al/(Fe+Mn+Al)、Fe/Ti比值以及Co/Zn-(Cu+Ni+Co)和Fe-Mn-(Cu+Ni+Co)图解揭示锰矿成矿过程中有海底热水的参与;稀土元素配分模式、Ce、Eu异常表示锰矿形成于被动大陆边缘环境,并具有热水沉积特征;碳同位素结果显示出富集碳的轻同位素的特征,反映了响涛源锰矿成矿过程中深部热水沉积及生物作用的特征;氧同位素计算古温度为湘中响涛源锰矿床的低温热水沉积成因提供了有利的佐证。     

The enthalpy of transformation of Ca(OH)2-I (portlandite) to Ca(OH)2-II (EuI2 structure) by low-temperature DSC

 Thermodynamic properties of high-pressure minerals that are not recoverable from synthesis experiments by conventional quenching methods (“unquenchable” phases) usually are calculated from equation of state data and phase diagram topologies. The present study shows that, with cryogenic methods of recovery and sample treatment, phases with a suitable decomposition rate can be made accessible to direct thermodynamic measurements. A set of samples of Ca(OH)₂-II has been synthesized in a multianvil device and subsequently recovered by cooling the high-pressure assembly with liquid nitrogen. Upon heating from liquid nitrogen to room temperature, the material transformed back to Ca(OH)₂-I. The heat effect of this backtransformation was measured by differential scanning calorimetry. A commercial differential scanning calorimeter (Netzsch DSC 404), modified to allow sample loading at liquid nitrogen temperature was used to heat the material from −150 to +200 °C at rates varying between 5 and 15 °C min⁻¹. The transformation started around −50 °C very gradually, and peaked at about 0 °C. To obtain a baseline correction, each sample was scanned under exactly the same conditions after the backtransformation was complete. Because of the relative sluggishness, onset and offset temperatures were not well defined as compared to fast (e.g., melting) reactions. To aid in integration, the resulting signals were successfully fitted using a generic asymmetric peak model. The enthalpy of backtransformation was determined to be ΔH =−10.37 ± 0.50 kJ mol⁻¹. From previous in situ X-ray diffraction experiments, the location of the direct transformation in P-T space has been constrained to 5.7 ± 0.4 GPa at 500 °C (Kunz et al. 1996). With the reaction volume known from the same study, and assuming that ΔC _p of the transformation remains negligible between the conditions of our measurements and 500 °C, our result gives an estimate of the entropy of transition and the P-T slope of the reaction curve. To a first approximation, the values ΔS = −16.00 ± 0.65 J(mol · K)⁻¹ and dP/dT = 0.0040 ± 0.0002 GPa/K have been determined. These results need to be refined by equation of state data for Ca(OH)₂-II. Received: 30 December 1999 / Accepted: 10 April 2000     

利用菱镁矿尾矿制备纳米级片状氢氧化镁

为了对菱镁矿尾矿进行综合回收利用,文中对利用菱镁矿尾矿制备纳米级片状氢氧化镁工艺进行了研究。通过对菱镁矿尾矿的煅烧、与硫酸反应制备硫酸镁以及纳米氢氧化镁的制备工艺和性能表征,成功制备了原始粒径为纳米级、颗粒呈片状的氢氧化镁粉体。利用轻烧镁粉制备硫酸镁溶液的工艺是将轻烧镁粉与水配制成浆料,然后与酸进行反应。反应后控制体系的pH值在5~6,然后进行过滤。制备氢氧化镁的工艺条件为:Mg2+初始浓度为22.75g/L,反应温度为50℃,反应时间为5min,原位表面改性剂为钛酸酯偶联剂YB-502,用量为氢氧化镁质量的1.5%。制得的氢氧化镁结晶情况良好,为片状纳米粉体,其片径100nm左右,片厚10nm左右。氢氧化镁的二次颗粒粒径为d50=0.95μm,d97=3.53μm。     

氢氧化镁处理含铬废水的研究

用硫酸亚铁将废水中Ｃｒ（Ⅵ）还原成Ｃｒ（Ⅲ）,再用氢氧化镁乳液和废水中的酸,使铬离子,铁离子氢氧化物沉淀,澄清分离,这样含铬废水经处理后,铬的含量及ｐＨ值有达到排放标准,该方法操作简便,效果显著。     

Role of Iron(III) and Aluminum Hydroxides in Concentration/reduction of Au(III) Complexes

Abstract: The adsorption of gold on iron(III) and aluminum hydroxides from solutions containing Au(III) complexes has been studied as a function of pH and chloride concentration at 30C. Iron(III) hydroxide was more effective in adsorbing gold from solution than aluminum hydroxide. However, both hydroxides controlled the behavior of Au(III) complex with very similar manner. The most effective gold adsorption occurred in aqueous solution with near neutral pH and low Cl concentration. In this solution condition, Au(III) complexes were mainly dissolved as AuCl₂(OH)₂^- and AuCl(OH)₃^-, and the surface charge for both hydroxides was positive. In addition, the adsorbed Au(III) complexes were spontaneously reduced to elemental gold in spite of the absence of a specific reducing agent.
The results of this study suggest that adsorption and spontaneous reduction of gold complexes on the surface of hydrous metal oxides with positive charge play an important role in gold precipitation in subsurface environment.     

High-pressure properties of diaspore,AlO(OH)

The structural compression mechanism and compressibility of diaspore, AlO(OH), were investigated by in situ single-crystal synchrotron X-ray diffraction at pressures up to 7 GPa using the diamond-anvil cell technique. Complementary density functional theory based model calculations at pressures up to 40 GPa revealed additional information on the pressure-dependence of the hydrogen-bond geometry and the vibrational properties of diaspore. A fit of a second-order Birch–Murnaghan equation of state to the p–V data resulted in the bulk modulus B ₀ = 150(3) GPa and B ₀ = 150.9(4) GPa for the experimental and theoretical data, respectively, while a fit of a third-order Birch–Murnaghan equation of state resulted in B ₀ = 143.7(9) GPa with its pressure derivative B′ = 4.4(6) for the theoretical data. The compression is anisotropic, with the a-axis being most compressible. The compression of the crystal structure proceeds mainly by bond shortening, and particularly by compression of the hydrogen bond, which crosses the channels of the crystal structure in the (001) plane, in a direction nearly parallel to the a-axis, and hence is responsible for the pronounced compression of this axis. While the hydrogen bond strength increases with pressure, a symmetrisation is not reached in the investigated pressure range up to 40 GPa and does not seem likely to occur in diaspore even at higher pressures. The stretching frequencies of the O–H bond decrease approximately linearly with increasing pressure, and therefore also with increasing O–H bond length and decreasing hydrogen bond length. Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users.     

理论计算阳离子对水体中B(OH)_3和B(OH)_4~-间硼同位素平衡分馏的影响

采用密度泛函方法模拟了阳离子对水体中B(OH)3和B(OH)4-的影响,计算海水的硼同位素平衡分馏参数。模拟海水环境时,选择基于分子簇模型的"水滴"法,以最多12个水分子环绕兴趣分子的方式构建"水滴"。对海水环境的计算结果显示,B(OH)3和B(OH)4-的硼同位素平衡分馏系数在25?C时为1.031,与纯水环境下的该分馏值并无明显差别。研究表明前人对B(OH)3和B(OH)4-间硼同位素平衡分馏参数的实验测定可能存在问题。研究结果为精进硼同位素古环境重建工作和硼同位素平衡分馏测定提供了理论制约。     

水溶液B(OH)_3和B(OH)_4~-间硼同位素平衡分馏参数的理论计算

采用密度泛函方法计算了水溶液中B(OH)3和B(OH)4-间硼同位素的平衡分馏参数。在模拟液相环境时,采用基于分子簇模型的"水滴"法,分别以6、12、18、24和30个水分子环绕兴趣分子的方式构建"水滴"。对纯水体系的计算结果显示该分馏参数在25?C时为1.031,与实验测定值吻合地非常理想。对不同个数水分子所形成的液相构型进行比较,发现在计算硼同位素的分馏时,12个水分子的"水滴"构型是比较经济和准确的建模方式。此外,我们还讨论了前人对该体系分馏计算中存在的不足,并提出了将分子簇模型扩展到碳酸盐矿物形成过程中硼同位素分馏研究的可能。     

A computer simulation study of (OH) defects in olivine

Recent experiments (Miller et al. 1987; Bell and Rossman 1992; Bai and Kohlstedt 1992) have shown that olivine, the dominant mineral in the Earth's upper mantle, can contain substantial amounts of water in the form of OH. There is uncertainty, however, as to the mechanisms by which water dissolves into the mineral structure and as to the site it occupies in the host lattice. We have therefore used atomistic computer simulation techniques based on the Born model of solids, to investigate the structures and energies of OH defects in olivine. Our calculations suggest that the most favourable route for incorporation of OH into olivine involves reactions with water accompanied by the reduction of ferric iron for which we obtain a solution energy of 0.46 eV. We propose therefore that the OH content will be largely controlled by the concentration of Fe³⁺.