【作者】 蓝卓越；

【导师】 胡岳华；

【作者基本信息】 中南大学 ， 矿物加工工程， 2005， 博士

【摘要】 高铁锌硫化矿在选矿分离上存在药耗大、成本高和回收率低的缺点,并且选别出的高铁锌精矿在传统湿法炼锌的焙烧—浸出工序中由于形成铁酸锌,降低了锌的浸出率,增大了冶炼难度。针对高铁锌硫化矿难选难冶的问题,本论文以取自广西大厂矿区的铁闪锌矿为研究对象,开展了高铁锌硫化矿的细菌浸出基础及其工艺研究。 研究应用的浸矿细菌是分离自广西大厂矿区锌硫化矿矿坑水的一组混合菌,其主要菌种组成是氧化亚铁硫杆菌、氧化硫硫杆菌和氧化亚铁钩端螺旋菌。论文研究了金属离子和非金属离子、表面活性剂以及能源基质对细菌的铁硫氧化活性及其浸矿过程的影响,通过浸矿试验、SEM、EDXA、XRD和电化学测试等研究方法和手段探讨了铁闪锌矿的细菌浸出机理和锌铁的浸出行为,在此基础上开展了含铁闪锌矿矿石和铁闪锌矿浮选精矿的细菌浸出研究,并进行了含锌细菌浸出液的溶剂萃取纯化研究和探讨,提出了锌硫化矿细菌浸出—萃取—电积工艺的基本流程。 离子和表面活性剂对细菌的铁硫氧化活性有影响,进而影响到细菌的浸矿过程。一定浓度的铜离子和表面活性剂OPD由于促进了细菌氧化元素硫,降低了浸出pH值,因此提高了铁闪锌矿的浸出速率。铜离子由于晶格取代形成的CuS或CuS₂对铁闪锌矿的浸出还具有电化学催化作用。 以不同能源基质培养得到的细菌表现出强弱不同的铁硫氧化活性,同时具备强氧化铁活性和强氧化硫活性的细菌具有较好的浸矿性能。以磁黄铁矿为能源基质培养得到的一组细菌具有良好的铁氧化活性和吸附特性,并且其硫氧化活性也未减弱,该细菌具有良好的浸矿性能。 铁闪锌矿的细菌浸出遵循收缩未反应核模型,浸出渣SEM、EDXA和XRD分析表明,未反应核界面的固体产物层是FeS、S和铁矾的混合物。当固体产物层比较致密或不断长大时,通过固体产物层的内扩散成为浸出反应速率的控制步骤,铁闪锌矿的浸出速率更多还原

【Abstract】 The processing of zinc sulfide ore bearing high content of iron involves high unit cost and low metal recoveries. Zinc ferrite（ZnO · Fe₂O₃） is formed when the concentrate of Zn bearing high content of iron is submitted to the roast-leach electrolysis process, which decreases the leaching rate of Zn and makes it difficult treated. One alternative for the treatment of the refractory zinc sulfide ore or zinc concentrate is bioleaching. The bioleaching of the marmatite sample, which was obtained from Dachang mine in Guangxi province, was carried out to investigate the bioleaching process for the refractory zinc sulfide ore or flotation concentrate.The bacteria applied in this research are a mixed culture isolated from the mine water of Dachang mine. Characterization of this culture showed that the main bacterial strains were Thiobacillus ferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans. The influences of various ions, surfactants and various cultures on the oxidation activities of the bacteria and the bioleaching of marmatite were studied. The mechanism of bioleaching of marmatite and the leaching behavior of Zn and Fe were discussed. On the bases of these researches, the bioleaching of marmatite ores and the flotation concentrate was conducted. The solvent extraction of zinc from the bioleaching solution was also studied. A basic technical process of bioleaching-solvent extraction-electrowinning for zinc sulfide was proposed.The ions and surfactants have influences on the oxidation activities and leaching capacity of bacteria. A certain concentration of copper ions or OPD can accelerate the S oxidation rate during bioleaching while the Fe oxidation activities of bacteria were hardly influenced. As a result, the bioleaching rate of marmatite was enhanced. The copper ions replace the zinc ions in the crystal lattice of marmatite as CuS or CuS₂, which also has electrochemical catalysis on the bioleaching of marmatite.The bacteria cultured on various mediums have different distributing of strains and show different oxidation activities of Fe and S accordingly. The bacteria that both have strong oxidation activities of Fe and S showed high leaching capacity. The bacteria cultured on the magnetic pyrrhotite, which were characterized by strong iron and sulfur oxidation activities and adsorption activities, and the oxidation activities of S were not weakened, showed high leaching capacity.The bioleaching of marmatite follows the shrinking core product layer model. SEM and EDXA analysis of the leaching residue indicated that the components of the product layer is a mixture of FeS, S and jarosite. When the product layer increased and became insoluble, the leaching rate is controlled by the diffusion through the product layer. In the case of being leached by bacteria with strong oxidation activities of Fe and S, the product layer was oxidized and decreased or became a porous layer, then the leaching rate was controlled by chemical reaction. The electrochemical aspects on bioleaching of marmatite were studied. In the case of low potential, a passivation film was formed on the surface of marmatite electrode. The presence of bacteria decreased the passivation and increased the leaching rate.According the energy band model for the leaching of marmatite, marmatite can be leached by Fe3+ ions and FT protons, and the reaction products were Fe ions and elemental S. Therefore, the marmatite can be leached by the bacteria with the only oxidizing ability of Fe or S. The role of the bacteria was to oxidize ferrous ions to ferric ions and oxidize elemental sulfur to sulfuric acid. The adsorbed bacteria on the marmatite surface firstly obtain the growth medium and grow well, and the metabolizing substances of the adsorbed bacteria accelerate the leaching rate of marmatite.The crystal structures of ZnS and FeS in marmatite are similar, but the crystal field stable energy of Fe in octahedral sites is greater than that of Zn in tetrahedral sites, so Zn is more likely to be leached than Fe. Bioleaching of marmatite ores and flotation concentrate with the bacteria cultured on pyrrhotite were carried out in shaking experiments.In the optimized conditions, the leaching rate of zinc reached above 96%, while the leaching rate of iron was only about 18%. The zinc in marmatie was selectively extracted.D2EHPA （di （2-ethylhexyl） phosphoric acid） was used as zinc extractant diluted in 260 # kerosene to extract zinc from the bioleaching solutions. A purified zinc sulfate solution was obtained through the process of solvent extraction, washing and stripping. A basic technical process of bioleaching-solvent extraction-electrowinning for zinc sulfide was proposed. The process is feasible on technique for zinc sulfide ores or the flotation concentrates.更多还原