【作者】 邓敬石；

【导师】 张宗华； 阮仁满；

【作者基本信息】 昆明理工大学 ， 矿物加工工程， 2002， 博士

【摘要】 Sulfobacillus thermosulfidooxidans为无机化能兼性自养菌，专性好氧，嗜酸，中等嗜热，最适生长温度50℃。能以Fe²⁺、硫化矿为能源自养生长，以酵母提取物为能源异养生长，有酵母提取物存在时，可氧化元素硫，在有机物存在的混合营养条件下该菌更易生长。S.thermosulfidooxidans在金属硫化矿物的浸出中起重要作用。 本论文选择混合营养条件，以亚铁离子为能源，在测定S.thermosulfidooxidans生长曲线的基础上，以Fe²⁺的氧化表征细菌的生长规律，考察影响细菌生长及亚铁氧化的主要因素。实验结果表明，初始pH1.6、接种量10％、初始Fe²⁺浓度50～100mM／l适宜细菌的生长及亚铁的氧化。 热力学及电化学分析表明，镍黄铁矿性质活泼，可进行简单酸溶。单矿物浸出实验证实，镍黄铁矿在酸性介质中自发分解，但浸出速度缓慢，8d仅浸出12.48％的镍；细菌的存在强化了镍黄铁矿浸出过程，添加酵母提取物8d浸出63.67％的镍，比无菌对照提高了55.63％。S.t菌浸出镍黄铁矿过程中，矿浆pH值、细菌接种量、矿浆浓度、酵母提取物用量是影响镍浸出率的主要因素。细菌浸出体系中，由于存在大量的NH₄⁺，H⁺，K⁺，SO₄²⁺，随着浸出过程的进行，镍黄铁矿溶解产生的Fe³⁺易与上述离子发生反应生成黄钾铁矾类物质，覆盖在矿物表面，对浸出不利。X-射线衍射分析证实，细菌浸出过程中确实生成该类沉淀物。S.t菌在无氧条件下，可利用黄钾铁矾表面的Fe³⁺作为最终电子受体，还原黄钾铁矾沉淀生长。当沉淀量较少时，生成的黄钾铁矾沉淀被S.t菌分解，对细菌浸出影响不大，但黄钾铁矾不能被完全还原，因而浸出过程中应尽量减少该沉淀的产生。 通过设计实验研究了S.t菌浸出镍黄铁矿的机理。研究表明S.t菌浸出镍黄铁矿单矿物过程中，细菌的直接侵蚀作用和高铁的化学氧化及酸浸作用同时发生，以细菌的直接侵蚀作用为主，高铁的化学氧化及酸浸作用是次要的。细菌扫描电镜照片证实浸出过程中细菌牢固吸附于镍黄铁矿表面。细菌对矿物的吸附具有选择性，细菌大多吸附于矿物颗粒裂缝及缺陷处。镍黄铁矿浸出前后矿物表面形貌变化表明，经细菌浸出后镍黄铁矿被严重侵蚀。 热力学及电化学分析表明，混合硫化矿物生物浸出过程中存在原电池效应。实验发现镍黄铁矿细菌浸出体系添加黄铁矿，加速了镍黄铁矿浸出过程。镍黄铁 昆明理工大学博士学广论文 中等嗜热菌强化镍黄铁矿浸出的研究 矿．黄铁矿混合矿浸出前后表面形貌观察及浸渣卜射线衍射分析结果证实细菌浸 出过程中镍黄铁矿优先选择溶解，黄铁矿则被阴极保护。 应用金川镍精矿进行了实际矿物细菌浸出实验，实验结果表明金川镍精矿易 浸出，无菌条件下，矿浆浓度二0，50，100浸出率分别为53．060，470，35．78％。； 细菌的加入加速了镍精矿的浸出。浸出过程中添加酵母提取物进一步改善了浸出 效果，2％矿浆浓度时6天浸出95石7％的镍。实际矿物比镍黄铁矿单矿物浸出效 果好。浸渣化学元素分析、浸出前后矿物表面形貌变化及浸渣卜射线衍射分析证 实金川镍精矿细菌浸出过程中由于原电池效应，镍黄铁矿、磁黄铁矿优先溶解， 黄铜矿、黄铁矿被阴极保护。此外，精矿含一定量的含镁碱性脉石，可为细菌生 长提供足够的镁离子，因此，培养基中不需额外补加含镁无机盐。更多还原

【Abstract】 A moderately thermophilic acidophilic facultative chemoautotrophic bacterium, Sulfobacillus thermosulfidooxidans is strictly aerobic, optimum growth at 50癈0 Autotrophic growth occurs with ferrous iron and mineral sulfides as substrates. It grows heterotrophicly on yeast extract. It can oxidize elemental sulfur in the presence of yeast extract and easily grows in mixotrophic condition. It plays important role in metal sulfide ore leaching.In this paper, on the basis of determining growth curve of Sulfobacillus thermosulfidooxidans, with bacterial growth being expressed by the oxidation of ferrous iron, the effect of initial pH, bacterial inoculation amount and ferrous iron concentration on bacterial growth and ferrous iron oxidation was investigated. Experimental results showed that initial pH 1.6, inoculation amount 10% and ferrous iron concentration 50~100mM/l was suitable for bacterial growth and ferrous iron oxidation in mixotrophic conditions.Thermodynamic and electrochemistry analysis show that pentlandite nature is lively. It can be carried out simply acid dissolution. Single mineral leaching experiment confirmed that pentlandite spontaneously decomposed in acid medium but it leached slowly. After 8 days it only leached 12.48% of nickel. The existence of bacterium has strengthened pentlandite leaching course, under the condition of adding yeast extract leaching rate of nickel reached 63.67%, the leaching rate raised 55.63% comparing sterile control. In the course of leaching pentlandite with S.t, mineral pulp pH, bacterial inoculation amount, solid loading and dose of yeast extract is the major factor which influences nickel leaching rate. Since in bacterial leaching systemhaving plenty of NH4+, H+, K+, SO 4", as leaching course going on, ferric ion producedfrom pentlandite dissolving easily reacts with above-mentioned ion and forms jarosite which covers mineral surface and prevents leaching continue. X - ray diffraction analysis confirmed that in the course of bacterial leaching this kind of precipitate definitely generated. S.t is able to reduce ferric iron and grows in anaerobic media with ferric iron in the jarositic surface precipitate as a terminal electron accepter.When precipitate quantity is lost comparatively jarosite is decomposed by S.t and its effect on bacterial leaching is not significant. It was found that the jarosite was not completely removed thus it should reduce this kind of precipitate produce as far as possible in the course of bioleaching.Through designing experiment, mechanism of pentlandite leaching with S.t has been studied. Research showed that bacterial direct erosion, ferric chemical oxidation and acid leaching at the same time occured in the course of leaching pure pentlandite, in which bacterial direct mechanism was dominant while acid and ferric chemical leaching was not important. Bacterial SEM photograph confirmed that bacteria strongly attached to the mineral surface in the course of leaching and the attachment of bacteria to mineral had selectivity, bacteria mostly attached to crack and defect of mineral. The change of mineral surface showed that after pentlandite bioleaching it had been seriously eroded.Thermodynamic and electrochemistry analysis showed that galvanic interactions existed in mixed sulfides bioleaching. In experiment it was found that adding pyrite to bacterial leaching system accelerated pentlandite leaching. The observation of pentlandite - pyrite mixed mineral surface and X - ray diffraction analysis results demonstrated that pentlandite dissolved priorly while pyrite was protected as cathode in bioleaching.Using nickel concentrates, actual mineral bioleaching was carried out. Experimental results showed that Jinchuan nickel concentrate was easy to leach. Under sterile control, the leaching rate at pulp density 2%, 5% and 10% were 53.06%, 47% and 35.78% respectively. In the presence of bacteria leaching effect was accelerated. Adding yeast extract the leaching effect was improved further. For solid loading of 2% the bioleachin更多还原