【作者】 闵小波；

【导师】 张传福； 钟海云；

【作者基本信息】 中南大学 ， 有色金属治金， 2000， 博士

【摘要】 难处理金矿是我国急待开发利用的宝贵资源。本文以广西金牙含砷难处理金矿为研究对象，开展了难处理金矿细菌氧化的基础理论及工艺研究，其主要内容如下： 系统研究了Fe²⁺离子氧化与细菌生长的规律。考察了各种因素对细菌氧化Fe²⁺离子的影响，建立了Fe²⁺离子浓度变化响应细菌生长的动力学模型：该模型确立了Fe²⁺离子浓度变化与细菌生长动力学参数μ_m、K、ρ_b⁰/Y之间的关系。根据实验中Fe²⁺离子浓度ρ随时间t变化，用计算机编程拟合，能快速确定细菌生长动力学参数；另一方面，通过改变细菌生长的动力学参数，可以从理论上预示细菌生长过程中Fe²⁺离子的氧化规律。 根据细菌浸出过程的特点，绘制了FeAsS-H₂O系、FeS₂-H₂O系电位-pH图。将此图与细菌活动电位-pH图进行有机结合，详细分析了细菌浸出过程中毒砂、黄铁矿溶解及产物生成的热力学。细菌生长环境正好处于矿物氧化溶解的范围，这表明细菌浸出毒砂、黄铁矿在热力学上是可能的。而毒砂、黄铁矿的浸出易于生成元素硫；一旦元素硫生成，由于其进一步氧化存在较高的势垒，如果没有细菌对其直接分解作用，三价铁离子不足以使它进一步氧化。此外，在毒砂、黄铁矿的浸出过程中，可能形成砷酸铁和黄钾铁矾两种沉淀产物。 采用新型矿物粉末微电极及稳态极化、循环伏安现代电化学测试手段，研究了毒砂、黄铁矿的电化学行为。考察了毒砂、黄铁矿的溶解规律。比较了细菌、三价铁离子及浸出过程中表面产物层对毒砂、黄铁矿浸出的影响，细菌的作用降低了黄铁矿的静电位，改变了黄铁矿表面物理化学状态，加快了黄铁矿的氧化；而细菌对毒砂的作用相对较小。在含三价铁的介质中，黄铁矿具有较强的反应惰性。 研究了黄铁矿、毒砂细菌浸出过程中主要参数（相关离子浓度、溶液pH值、电位、细菌浓度）变化的不同特点。黄铁矿细菌浸出过程中，溶液pH值显著下降，细菌大量吸附在黄铁矿表面，对于毒砂，溶液pH值下降平缓，表面吸附细菌较少。采用现代微区检测技术（SEM、EDS、XRD）详细分析了 中币大学瞩士学位论文 中文拘要 黄铁矿、毒砂浸出过程中表面性质的变化及最终产物的组成。黄铁矿表面形貌 呈现明显的选择性腐蚀特征，且硫优先溶出，浸出后主要产物为黄钾铁矾类物 质；而毒砂的腐蚀则在整个表面发生，表现出均匀腐蚀的特点，砷优先溶出， 浸出产物为元素硫、砷酸铁和黄钾铁矾。黄铁矿、毒砂细菌浸出过程特性的研 究发现黄铁矿、毒砂的氧化分别以细菌的直接作用和间接作用为主。这澄清了 许多文献报道的有关矿物细菌浸出的直接机理和间接机理的混乱之争。在此基 础上，通过建立黄铁矿、毒砂细菌浸出的能带模型，进一步阐明了细菌浸出的 机理。毒砂的腐蚀与三价铁离子产生的空穴注入价带有关：而黄铁矿的腐蚀则 主要通过吸附在表面的细菌将山溶解氧产生的空穴注入价带引起。 自行设计并组装了实验室规模的细菌半连续浸出新型流态化床反应器。研 究了广西金牙含砷浮选金矿细菌预氧化脱砷－氰化工艺，获得了理想的结果。 在叫值 2乃、三价铁离子浓度 6．sg／L、矿浆浓度 10％、浸出时间 4天的条件 下，批式流态化细菌浸出的脱砷率为82．5％，后续金的氰化浸出率为90％。用 3个串联的流态化生物反应器对金精矿进行半连续试验，浸出过程中各槽参数 表现了较好的稳定性，56天内砷的脱除率为 gi％，浸出 3一天也可脱除掉 82％ 的砷，后续的氰化浸金实验中金的浸出率分别可以达到 92％和 87．5％。研究结 果可为含砷难处理金矿细菌浸出的工业实践提供重要依据。更多还原

【Abstract】 Fundamental and technological studies on bioleaching of arsenic-bearing refractory gold concentrates by 77 ferrooxidans were carried on, with GuanXi JinYa gold concentrates being the developed objective of this research. The main subjects in this dissertation are as follow抯:The relationship between the oxidation of ferrous ion and 77 ferrooxidans growth has been studied systematically. Factors affecting biooxidation of ferrous ion were discussed, a response model for bacterial growth in the substrate containing ferrous ion was also built. It can be expressed as,p梉(p~IY)+p01 +K_______________p0梉(p~/Y)+p0] (p~/Y)+p0 p{p0梉(p~/Y)+p0]}The model shows the variation of ferrous ions concentration with the kinetics parameters of bacterial growth such as Li m ,K and P b/1~ Via the computer simulation to the concentration of ferrous ion during Tferrooxidans growth, the kinetic parameters of the bacterial growth were determined. The model, furthermore, can predict the influences of these parameters on the biooxidation of ferrous ion, with changing the parameter valuesAccording to the aspect of bioleaching process, the potential ?pH diagrams for arsenopyrite-water and pyrite-water systems were drawn, with which was combined the potential-pH diagram for TJ鑢rooxidans activity. A thermodynamic behavior for the bioleaching of pyrite and arsenopyrite has been examined. Tferrooxidans is active in the regions for dissolving pyrite and arsenopyrite, so pyrite and arsenopyrite is possible to be bioleached thermodynamically. It is easy to form element sulfur during the leaching of pyrite and arsenopyrite. If there is no direct action of Tferrooxidans on the formed sulfur, it is impossible for ferric ion to dissolve the element sulfur because of existing a high-energy obstacle in the furtherVIcontinues way, by which a process for biooxidation ?cyanidation of Guangxi Jinya refractory gold arsenical concentrate was studied. An arsenic extraction rate reaches 82.5% after 4-day batch biooxidation of the concentrate under the optimized condition of pH 2.0, ferric ion concentration 6.5 gIL and pulp density 10%. And leaching rate of gold in the following gold cyanidation is over 90%. The parameters of three series fluid-bed reactors exhibit stability during the semi-continues bioleaching of the concentrate. Arsenic in the concentrate can be got rid of 91% after 6-day leaching. Even after 4 days, 82% of arsenic extraction rate was still obtained. The recovery rates of gold are 92% and 87.5% respectively in cyaniding the above bioleached sludges. The results will provide a base for further commercial production of gold development.更多还原