Batch and semi-continuous tests in the bioleaching of manganiferous minerals by heterotrophic mixed microorganisms

In the present paper a study on bioleaching of manganiferous ores by heterotrophic mixed cultures is reported. The main goal of this work has been to study the bioreduction process of MnO₂ in lab-scale reactor and pilot plant tests, in order to investigate the process' pergormances in a scale larger than in shaken flasks. Lab-scale reactor tests were carried out in a batch and in a semi-continuous regime, monitoring manganese extraction yields and microbial growth. In the bioleaching tests 95–100% of manganese extraction (in 36–48 h of treatment using a content of pulp equal to 20% (w/v) of ore having a Mn grade of 17–20%) was obtained. Final tests in a pilot plant (V = 70L) were performed under non-sterilised conditions. From the experimental results a flowsheet of the process has been proposed. An approximate economical analysis of the bioleaching process has also been reported. The experimental results showed the technical feasibility of the process although several problems have to be resolved to allow for a full-scale application, such as the biomass disposal, the purification of the leach liquor before the final manganese recovery and the too high cost of the process.     

阿刀亥矿区CP2煤段粘土岩夹矸研究

内蒙大青山煤田ＣＰ２煤段含粘土岩夹矸多达４０余层。与上覆ＣＰ３砾岩段冲刷接触的煤段顶板和顶部粘土岩夹矸，为伊利石或伊利石－高岭石粘土岩。其下煤段中夹矸及底板为高岭石粘土岩，均发生了不同程度的铵云母化和一水硬铝石化。鳞片状、纤维状、条片状及晶粒假象铵云母沿粘土岩夹矸的节理裂隙呈脉状产出；微、细晶一水硬铝石沿碳质碎屑条带及富有机质的高岭石基质条带分布。这些特征表明，在有Ｋ＾＋离子带入的开放条件下，粘土     

碳酸盐矿物氧同位素分馏的理论研究

应用增量方法系统地计算了碳酸盐矿物的同位素分馏系数，得到不同结构和成分的碳酸盐矿物的18O富集顺序为：菱铁矿〉铁白云石〉菱镁矿≥白云石≥方解石〉文石〉菱锶矿〉白铅矿〉碳钡矿。在0℃～1200℃范围内获得了一组内部一致的碳酸盐－水体系的理论分馏系数，这些计算结果与已知的实验和／或经验数据之间存在良好的一致性，因此本文对碳酸盐矿物氧同位素分馏系数的理论校准不仅可应用于共生矿物组合形成温度的确定，而且能够应用于其形成机理的示踪。 计算结果表明，白云石的氧同位素分馏行为与方解石相似，在25℃下白云石与方解石之间的平衡分馏为0.56‰ 。理论预测文石相对于方解石显著地亏损 δ18O，在25℃时方解石与文石之问的平衡分馏为4.47‰ 。文石向方解石的同质多相转变可能是通过一种没有同位素再造的惰性氧结构单元[CO3]2- 进行的，即只涉及Ca2+ 与[C03]2- 基团之间键的断裂和再组台而未出现[CO3]2- 基团内部C－O键的断裂和再组合。结果在自然界和实验室实验中，文石中氧同位索配分的温度关系能够传递副方解石中来。这种在同质多相转变形成方解石过程中的氧同位素继承性对于了解白云石－方解石－水体系分馏的难题至关重要。理论预测也能够用来解释对方解石分馏的经验估算与实验测定之间的分歧。     

Remediation of heavy metal-contaminated sediments by solid-bed bioleaching

 Weisse Elster River sediment from the Leipzig Lowlands region (Saxony, Germany) is anthropogenically polluted by heavy metals. Sediment dredged from a trap to the south of Leipzig was characterized in detail. When freshly dredged sediment contacts air, the material turns acidic because of oxidation processes, the heavy metals become soluble and the sediment poses an environmental risk. We are therefore developing a sediment-treatment process based on heavy metal removal by bioleaching. Leaching experiments were carried out in suspension and in the solid bed. The heavy metals were solubilized to nearly the same extent by H₂SO₄ dosage (pure chemical extraction) and addition of elemental sulphur (microbial oxidation of S⁰ to H₂SO₄). With increasing dosage of the leaching agent, Zn, Cd, Ni, Cu and Cr were more and more solubilized, whereas Pb was only dissolved in small amounts. The addition of 2% S⁰ is considered an optimum dosage. When 5% S⁰ was added to the sediment, the pH dropped to 1.76 and large amounts of undesirable compounds such as Ca, Al and Fe were solubilized. The higher the temperature, the faster the metals were solubilized in both suspension and the solid bed. The temperature optimum for activating the indigenous S⁰-oxidizing microbes of the sediment lies between 30 and 40  °C. Conditioning of freshly dredged sediment with plants makes it suitable for solid-bed leaching; the kinetics of heavy metal solubilization from sediment conditioned for 6 months with Phragmites australis was the same as from long-term stored sediment. Received: 26 November 1999 · Accepted: 5 May 2000     

Fractal Geometry of Element Distribution on Mineral Surfaces

Fractal models have been established for the distributions of Au, As, S, Fe, and Si on mineral surface based on perimeter–area power-law association observed in mineral samples from fine-disseminated gold deposits at Jinya (JY), Larima (LRM), and Dongbeizhai (DBZ). The fractal index D_AL, involved in the fractal perimeter–area relationship is a function of the formation conditions of the mineral. Minerals formed at higher temperatures have a larger value of D_AL. For the same mineral, the values of D_AL obtained for different elements are approximately the same. D_AL may serve as a quantitative index characterizing the distribution configuration of elements on mineral surface.     

南极中山站地区粘土矿物高岭石的分布和成因探讨

在南极中山站地区的土壤和湖泊沉积物中都有高岭石存在，本文分析了这些土壤样品的水溶态镁离子和ｐＨ值。结果表明，中山站地区土壤中的高岭石含量存在明显的空间分异，含量范围为２６％～５７％；而中山站地区奈拉湖不同时间的湖泊沉积物中高岭石含量范围则为５．８％～２３．２％。通过研究土壤中高岭石含量和土壤溶液性质的关系，发现土壤中高岭石含量与土壤溶液的ｐＨ和水溶态镁离子有一定联系。奈拉湖沉积物中高岭石的时间变化表明土壤中的高岭石含量在百年尺度上即可发生明显改变，这和土壤溶液性质发生改变的时间尺度是一致的。     

动植物在金矿找矿中的应用

利用特定的动物、植物寻找黄金资源已取得比较明显的进展。对部分特定动物、植物的富金能力进行了简要介绍，初步认为，它已构成一种有效的找矿方法与指示标志。在具有类似条件的地区，可开展此项工作。     

粤西茶洞银金矿床矿物流体包裹体地球化学研究

茶洞矿床是粤西地区一个较为典型的蚀变破碎带型多金属矿床。矿物流体包裹体研究表明：该矿床成矿温度160～341℃，成矿压力2．7×106～2．43×107Pa，流体盐度（4．1～15．9）wt％NaCl，流体密度0．880～0．942g／cm3，fCO2为103.7～10.4.3，fs2为10－14.50～10-11.67，fO2为10-45.0～10－35.1，成矿从早至晚均逐渐降低；成矿流体pH值为4．70～7．07，Eh值为－0．65～－1．15，该矿床形成于弱酸性一中性，强还原的物理化学环境；成矿流体为岩浆水与大气降水的混合热液，成矿早阶段以岩浆水为主，到成矿晚阶段，大气降水逐渐增多。     

Study of the Stacking Sequences of an Irregular Mixed-Layer Illite/Smectite (I/S) Clay Mineral—with a Discussion on the Existence of Minerals with Two-Dimentional Lattice and One-Dimentional Quasi-Lattice

There are two aspects in the study of irregular mixed-layer clay minerals: one is the kinds and ratios of their basic structural unit layers and the other is the junction probabilities of the unit layers. Irregular mixed-layer illite/smectite clay minerals (I/S) are widespread in nature. While studying the clay minerals from the Permian-Triassic (P/T) boundary bed, the authors found that I/S clay minerals are developed in all P/T boundary clay layers in areas from the northwest to southeast of China. Systematic mineralogical studies of the I/S clay minerals from Hunan, Hubei, Sichuan and Zhejiang were made by means of X-ray, infrared spectroscopic, electron microscopic and chemical analyses and a deepened study of the stacking sequences of their structural unit layers was conducted by the MacEwan one—dimentional direct Fourier transform. It was found that the stacking of the illite and smectite crystal layers along the c axis can be derived from Fibonacci sequences. Hence, the authors propose that such I/S clay minerals are possessed of two—dimentional crystal lattice and one—dimentional quasicrystal lattice.     

Pseudotachylite from the Main Zone of the Hidaka metamorphic belt, Hokkaido, northern Japan

Pseudotachylite veins have been found in the mylonite zone of the Hidaka metamorphic belt, Hokkaido, northern Japan. They are associated with faults with WNW-ESE to ENE-WSW or NE-SW trends which make a conjugate set, cutting foliations of the host mylonitic rocks with high obliquity. The mylonitic rocks comprise greenschist facies to prehnite-pumpellyite facies mineral assemblages. The mode of occurrence of the pseudotachylite veins indicates that they were generated on surfaces of the faults and were intruded as injection veins along microfractures in the host rocks during brittle deformation in near-surface environments. An analysis of the deformational and metamorphic history of the Hidaka Main Zone suggests that the ambient rock temperature was 200–300° C immediately before the formation of the Hidaka pseudotachylite. Three textural types of veins are distinguished: cryptocrystalline, microcrystalline and glassy. The cryptocrystalline or glassy type often occupies the marginal zones of the microcrystalline-type veins. The microcrystalline type is largely made up of quench microlites of orthopyroxene, clinopyroxene, biotite, plagioclase and opaque minerals with small amounts of amphibole microlites. The interstices of these microlites are occupied by glassy and/or cryptocrystalline materials. The presence of microlites and glasses in the pseudotachylite veins suggests that the pseudotachylites are the products of rapid cooling of silicate melts at depths of less than 5 km. The bulk chemical composition of the pseudotachylite veins is characterized by low SiO₂ and a high water content and is very close to that of the host mylonitic rocks. This indicates that the pseudotachylite was formed by virtual total melting of the host rocks with sufficient hydrous mineral phases. Local chemical variation in the glassy parts of the pseudotachylite veins may be due to either crystallization of quench microlites or the disequilibrium nature of melting of mineral fragments and incomplete mixing of the melts. Pyroxene microlites show a crystallization trend from hypersthene through pigeonite to subcalcic augite with unusually high Al contents. The presence of pigeonite and high-Al pyroxene microlites, of hornblende and biotite microlites and rare plagioclase microlites may indicate the high temperature and high water content of the melt which formed the pseudotachylite veins. The melt temperatures were estimated to be up to 1100° C using a two-pyroxene geothermometer. Using published data relating water solubilities in high-temperature andesitic magmas to pressure, a depth estimate of about 4 km is inferred for the Hidaka pseudotachylites. Evidence derived from pseudotachylites in the Hidaka metamorphic belt supports the conclusion that pseudotachylite is formed by frictional melting along fault surfaces at shallow depths from rocks containing hydrous minerals.