【作者】 张雁生；

【导师】 覃文庆； 陈淼；

【作者基本信息】 中南大学 ， 矿物加工工程， 2011， 博士

【摘要】 本文采用筛选富集的高效浸矿细菌,以黄铜矿相态的溶解特性及其细菌浸出过程中黄铜矿物相和化学转化为研究对象,采用电化学、XRD和表面分析方法SEM,及其澳大利国家同步辐射中心同步辐射X射线衍射在线分析方法,对黄铜矿相态转化和浸出过程中黄铜矿物相及化学转化过程进行了系统的研究。针对筛选富集的高效浸矿混合菌,进行了基础的生理特性研究。结果表明,该菌对温度和pH具有较宽的适应区间,适宜的生长温度为25-40℃C,最佳生长温度为30℃；适应的生长pH范围1.0～3.5,最佳生长pH为2.0。适宜生长电位区间为502-750mV vs.SCE具有较高的亚铁和硫的氧化活性,在最佳生长条件下,培养60小时,亚铁氧化率为96%；培养120h,溶液pH有初始值2.0下降到0.8。该菌对Cu2+、总铁、Ni2+和Mg2+的耐受浓度分别为：20g/L、25g/L、12g/L和20g/L绘制了Cu、Fe、S三种元素-H2O、Cu-S-H2O、Fe-S-H20、接近实际条件下的Cu-Fe-S-H20体系以及常见硫化矿物Eh-pH图。分析得知：在细菌浸出体系中, Fe2+/Fe3+的理论转化电位值为0.771v。Cu2+是细菌浸出过程中铜的稳定存在组分,电位小于0.161V时Cu+可能存在；硫元素以多种价态形式存在,高电位条件下,HS04-、SO42-为热力学的稳定组分,pH=1.99为转化平衡条件。低电位、高pH时,元素硫还原为H2S,随着电位变得更负pH更高时,H2S将转化为HS-,pH大于6时,随着电位的升高,HS-被氧化为S042-；pH小于6时,电位的升高促进H2S经由元素硫,逐步被氧化为S4062-、S2032-、S02、HSO-及S2062-；在碱性条件下,HS-将被氧化为SO32-,继而被氧化为+5价的S2062-。硫化铜矿的细菌浸出体系中,辉铜矿Cu2S和铜蓝CuS具有较宽的稳定存在区间,是铜铁硫化矿物溶解过程的中间物质。CuFeS2的溶解过程有CuFeS2→CuS→Cu2+或CuFeS2→CuS-Cu2S→Cu2+两种途径。铁的优先溶解是铜铁硫化矿物分解的初始步骤。黄铜矿相态转化试验结果表明：小于200℃时,黄铜矿以饺相α稳定存在,其晶格a=b=5.2894A,c=10.4221A。200℃C-420℃范围内,随着温度的升高,黄铜矿晶格快速增大。在552℃条件下,随着焙烧时间的延长,黄铜矿晶格显著增加。硫元素在其相态转化过程中起着关键作用。同步辐射原位相变试验表明,黄铜矿相变过程可分为三个阶段,第一阶段温度范围在200℃-490℃,黄铜矿以四方晶体存在,晶格随温度的升高增大；第二阶段温度范围在490℃C-550℃,黄铜矿由四方晶系转为立方品系,品格继续增大。第三阶段温度范围在55O℃-600℃,黄铜矿以立方晶体的形态存在。混合细菌浸出24天,自然黄铜矿、203℃、382℃和552℃条件下焙烧所得黄铜矿中铜的浸出率为30.98%、32.99%、40.54%和60.95%。黄铜矿的晶格增大,晶格能降低,是浸出率显著提高的组最根本原因。各相态黄铜矿电化学研究显示,随着焙烧温度的升高,黄铜矿的静电位降低,自然黄铜矿的静电位为214mV,203℃、382℃C及552℃条件下静电位分别为188mV、176mV和56mV。各相态黄铜矿阳极氧化过程相同,出现三个黄铜矿氧化特征峰。但随着温度升高所得黄铜矿还原过程特征峰减少。退火温度的升高导致腐蚀电流密度增加,腐蚀电压降低,极化电阻减小。自然黄铜矿的腐蚀电流密度为0.461μA.cm2,203℃和382℃下的分别增大到0.457μA-cm-2、0.837μA.cm-2,552℃时,黄铜矿腐蚀电流密度增大到2.221μA.cm-2。自然黄铜矿的极化阻力为80.31kΩ.cm,203℃和382℃下的极化阻力分别为54.03kΩ-cm2、28.84kΩ.cm2,552℃下,黄铜矿的极化阻力下降到9.09kΩ-cm2。在黄铜矿整个浸出过程中,Cu8S5和Cu339Fe0.61S4为黄铜矿浸出初期的中间产物出现。Cu3.39Fe0.61S4中铜铁硫原子个数比为5.5：1：6.5,为铜铁的富硫化合物,Fe优先溶解为黄铜矿溶解的初始步骤。斑铜矿的溶解初始步骤为铁的优先溶解,形成非化学计量的铜铁硫化合物CuxFeySz,在细菌和高铁等的氧化下,斑铜矿溶解过程生成了Cu8S5、Cu7S4、Cu39S28、CuS、Cu2S等中间物质。斑铜矿溶解基本过程可描述如下：黄铜矿的浸出基本分为两个阶段,第一阶段,亚铁氧化均为优势细菌,浸出速率高,电位快速升高；第二阶段,硫氧化菌为优势浸矿细菌,铜浸出率平稳,电位稳定,溶液pH显著降低。分阶段接种细菌,将大大促进硫化铜矿的溶解,第二阶段初期添加At和A.caldus后浸出到75天后,铜浸出率为43.78%。细菌柱浸出过程中,混合菌B的浸出效果最好。当细菌接种量为10%、矿石粒度：-10+5mm、喷淋强度：3ml/cm2.h、自然温度条件下,浸出75天,铜浸出率为43。64%。矿石粒度、喷淋强度对铜的浸出有显著的影响。更多还原

【Abstract】 The dissolution characteristics of different phase chalcopyrite and its mineralogical and chemical phase transformation were systematically investigated by electrochemical measurements, XRD, SEM and in situ Powder Diffraction of Synchrotron, during bioleaching by the adapted effective bacteria.The physiological characteristics of the adapted culture were studied. It was showed that the culture had a wide growth range of temperature (25-40℃) and pH (1.0-3.5), with the optimal temperature at30℃and pH at2.0. This culture had fairly high oxidative activity of ferrous ion and S0.96%ferrous ion were oxidized in60hours under the optimal condition in9K medium, and the pH of medium decreased to0.8cause of the oxidation of S0into SO42-. This culture could resist Cu2+, total Fe, Ni2+and Mg2+up to20g/L,25g/L,12g/L and20g/L respectively. And the optimal potential range was502-750mV vs. SCE.Eh-pH diagrams of Cu-H2O, Fe-H2O, S-H2O, Cu-S-H2O, Fe-S-H2O as well as Cu-Fe-S-H2O system for physical conditions and sulfide minerals-H2O were drew. It was obsevered that the iron mainly existed as Fe2+and Fe3+, of which the theoretical potential of transformation was0.771V. Cu2+was the stable component of copper in of bioleaching of copper sulphide, and Cu+might exist while the potential was below0.161V. S existed in multiple valence states, HSO4-and SO42-were stable components in higher potential, while pH=1.99was the equilibrium condition of transformation. At lower potential as well as higher pH, sulphur was reduced to H2S, H2S translated into HS-with the potential reduce and pH increase. Moreover, HS-was oxidized to SO42-with potential increased at pH above6. While less than6, H2S was oxidized to S0, S4O62-,S2O32-, SO2, HSO-and S2O62-. HS-would be oxidized to SO32-, and then to S2O62-at alkalic solution. In the bioleaching of copper sulfide, there was a relatively broad region for the existence of Cu2S and CuS which were the intermediate product in the dissolution of copper-iron sulfides. The CuFeS2could be dissolved by two ways as CuFeS2→CuS→Cu2+and CuFeS2→CuS-Cu2S→Cu2+. Preferential release of iron from sulfide minerals was the first step of copper-iron sulfide minerals dissolution.The chalcopyrite with different phase was obtained by quenching at desired temperature and the basic properties of the chalcopyrite weith different phase were also investigated. As shown from the result of XRD, when chalcopyrite was quenched below200℃, it existed in the stable form of phase a, the parameters of lattice was a=b=5.2894A, c=10.4221A, respectively. As for the sample quenched between200℃and420℃, the lattice size of the quenched chalcopyrite increases rapidly as long as the temperature increased. For the sample quenched at552℃, the lattice size of chalcopyrite increased significantly with the roasting time. Elemental sulfur played a pivotal role in the process of chalcopyrite phase modification. The in situ study of the phase transformation indicated that the phase modification of chalcopyrite could be divided into three stages:in the first stage, chalcopyrite presented as tetragonal crystal, the lattice size increased with the temperature. The second phase of the temperature ranging from490℃to550℃, chalcopyrite had accomplished the process of phase modification, in which chalcopyrite transferred from tetragonal crystal to cubic crystal with the lattice size increased. The last phase of the experiments, temperature ranging from550℃to600℃, chalcopyrite existed in form of cubic crystals in the zone. The mixed bacterial leaching test showed that, when chalcopyrite was roasted under the conditions of natural temperature,203℃,382℃and552℃, the leaching rate of copper were30.98%,32.99%,40.54%and60.95%, respectively. The high leaching rate mostly lies in the larger chalcopyrite lattice size and lower lattice energy.The electrochemical studies of the chalcopyrite with different phases showed that the Open Circuit Potential reduced as the quenched temperature increase. The Open Circuit Potential of nature chalcopyrite was214mV, and188mV at203℃,176mV at382℃and56mV at552℃. The anodic oxidation process of the different phase chalcopyrite was similar to nature chalcopyrite and three oxidation peaks was determined. However, with temperature increased, the cathodic peaks reduced. The corrosion potential of the different chalcopyrite modification electrode decreased and the corrosion current density increased with the roasting temperature. The corrosion current indensity of nature chalcopyrite was0.461μA·cm-2, and increased to0.457μA·cm-2and0.837μA·cm-2at203℃and382℃, respectively, finally reduced to2.221μA·cm-2at552℃. The corrosion resistance of nature chalcopyrite was80.31kΩ·cm2and it were54.03kΩ·m2and28.84kΩ·cm2quenched at203℃and382℃respectively. The corrosion resistance reduced to9.09kΩ·cm2at552℃In the bioleaching of chalcopyrite, Cu8S5and Cu3.39Fe0.61S4was observed as intermediate products. The ratio of Cu Fe S is5.5:1:6.5in Cu3.39Fe0.61S4which was the copper-iron sulphied with abundant sulpher. Preferential dissolution of iron was the first step of chalcopyrite dissolution. CuxFeySz was determined as the product of the first step of bornite dissolution caused by the preferential release from bornite. In addition, Cu8S5, CU7S4, Cu39S28, CuS, Cu2S and other intermediate substances formed during the bioleaching of bornite. The dissolution bornite could be described as followas:The bioleaching of chalcopyrite by mixed culture and A.f was carried out. It was indicated that the bioleaching process could be devided into two steps. At first step the preponderant bacteria was iron oxidation bacteria, furthermore, the leaching rate keep in high level and the redox potential increased rapidlly. However, at the second step the sulphur oxidation bacteria were preponderant. The redox potential keep at stable and the pH of solution reduce significantly because of the oxidation of sulpher by the sulphur oxidation bacteria. Furthermore, the copper extraction was enhached by inoculating the sulphur oxidation bacteria at the end of the fist step, resulting as the the copper extraction reached to43.78%after leaching for75days throuth inoculating the A.t and A.caldus into the leaching system.The extraction of copper reached43.64%after leaching75days by mixed culture B using the column reacter with the partical size of ore at-10+5mm, spraying intensity3ml/cm2·h and at natural temperature.更多还原