氧化亚铁硫杆菌的固定化及其在矿物浸出中的应用研究
文献类型：学位论文
| 作者 | 龙中儿 |
| 学位类别 | 博士 |
| 答辩日期 | 2003 |
| 授予单位 | 中国科学院过程工程研究所 |
| 授予地点 | 中国科学院过程工程研究所 |
| 导师 | 欧阳藩 |
| 关键词 | 氧化亚铁硫杆菌 聚乙烯醇 固定化 硫化矿 浸出 祸合 |
| 其他题名 | Immobilization of Acidithiobacillus ferrooxidans and Its Application on Leaching of Sulfide Ores |
| 学位专业 | 化学工艺 |
| 中文摘要 | 矿物生物浸出技术因能充分利用资源，且成本低、投资少，基本上无环境污染等，已成为矿物加工工程领域中发展最快、研究最为活跃的领域之一。氧化亚铁硫杆菌是生物浸出中研究和应用最为广泛的一种微生物。传统的生物浸出工艺是细菌的生长、细菌对Fe2＋的氧化和矿物的浸出在同一环境条件下同步进行，细菌生长受到高矿浆浓度和重金属离子等逆境的抑制，其氧化速度缓慢，矿物浸出效率较低，工业应用还受到一定的限制。基于生物浸出的间接作用机理，本文将传统的矿物生物浸出过程分为细菌氧化Fe2＋的生物反应过程和细菌氧化产物浸出矿物的化学反应过程，并将细菌氧化Fe2＋的生物反应过程通过固定化细胞来实现，构建了有效的固定化细胞氧化硫酸亚铁一氧化产物硫酸铁浸出矿物的矿物浸出新工艺与设备，旨在建立一种较经济、高效、较具有普适性的矿物浸出新工艺。主要研究内容和结果如下：（l）为避免Fe2+的生物氧化产物Fe3＋在目前常用Fe2＋氧化细菌的生长pH条件下 （pH＞2.0）易形成不溶性复合物而不利于祸合工艺的实现，实验从最适生长pH2.0-3.0的氧化亚铁硫杆菌出发，经定向驯化培育和连续培养分离获得在pH＜2.0条件下高效氧化Fe2＋的驯化氧化亚铁硫杆菌。除起始pH外，该驯化氧化亚铁硫杆菌氧化Fe2＋的适宜条件及其比生长速率都和出发菌株相近，比生长速率为0.06351／h。（2）从载体的机械强度、稳定性以及比表面等综合考虑，通过实验确定了聚乙烯醇适合作为氧化亚铁硫杆菌的固定化载体，以及适合氧化亚铁硫杆菌的固定化条件，并分别通过聚乙烯醇一硼酸交联法和聚乙烯醇冻融法制备了氧化亚铁硫杆菌的两种固定化细胞，分别称为聚乙烯醇一硼酸凝胶和聚乙烯醇冻融胶，其细胞包埋量皆为109 cells／ml。（3）经聚乙烯醇固定化的氧化亚铁硫杆菌氧化Fe2＋的适宜温度、pH值均与游离菌相同，但动力学研究结果表明，在89／L的Fe2＋浓度条件下，两平行填充床（Φ3.5 cm x40 cm）生物反应器内的聚乙烯醇一硼酸交联法和聚乙烯醇冻融法制备的固定化氧化亚铁硫杆菌氧化Fe2＋的动力学常数分别为0.4 L／L/h和0.6 L／L／h，即聚乙烯醇冻融法制备的固定化氧化亚铁硫杆菌氧化Fe2＋的效率要高于聚乙烯醇一硼酸交联法；另外，高Fe2＋浓度对固定化细胞的氧化活性有抑制作用。（4）酸性硫酸铁溶液能够浸出金川低品位镍铜矿中的镍和铜、江西东乡硫化铜矿及人工合成硫化铜中的铜，浸出动力学依矿物结构和浸出方式的不同，分别受化学反应控制、扩散控制或混合控制。尽管受浸出介质中的硫酸铁浓度、温度、pH及矿物粒度的影响，酸性硫酸铁溶液的浸出效率要优于细菌、矿物、气体三相浸出体系。（5）构建了固定化细胞氧化硫酸亚铁一氧化产物硫酸铁浸出矿物的拙合工艺，并以金川低品位镍铜矿为浸出对象进行连续实验研究，在固定化细胞生物反应器稀释率为0.21/h，矿物浓度为5％，矿物粒度为-300目，浸出温度为70℃的条件下，固定化细胞氧化硫酸亚铁一矿物槽浸祸合浸出24h，矿物中镍和铜的浸出率分别达82.0％和65.9％：在同样的固定化细胞生物反应器稀释率及-20目十40目的矿物条件下，固定化细胞氧化硫酸亚铁一矿物柱式渗滤浸出39天，矿物中镍和铜的浸出率分别达87.3％和51.3％。（6）构建了固定化细胞氧化硫酸亚铁一氧化产物硫酸铁浸出矿物批合工艺的半经验模型，分析了该工艺浸出矿物的优越性及其存在的问题。 |
| 英文摘要 | The technology of bioleaching sulfide minerals has been one of the most active research field with a quick developing step in the mining industry, for its simplicity, low cost, relatively high recovery of metal, low environmental pollution and applicability to low-value ores. However, the current industrial application of bioleaching process, in which biooxidation of ferrous iron and leaching of ores happened at the same time, was limited for its slow kinetics and poor leaching efficiency. In this paper, based on the theory of indirect bioleaching mechanism of sulfide minerals, the bioleaching process of ores was separated into two subprocess: the chemical oxidation of sulfide minerals by Fe + and the bacterial regeneration of Fe + as leaching agent that can be achieved with immobilized Acidithiobacillus ferrooxidans, which is a widely studied microorganism, a novel technology of chemical leaching of sulfide ores coupled with biooxidation of ferrous iron by immobilized At. ferrooxidans was established to accelerate the biooxidation rate of ferrous iron and then promote the leaching efficiency. The main research contents and results obtained are as follows : A strain of At. ferrooxidans, oxidating ferrous iron effectively at low pH (pH<2.0), was adapted by sequential adaptive culture and isolated via continuous culture. Compared with the original At. ferrooxidans TF5, its optimum pH for oxidating ferrous iron was changed from pH2.0~3.0 to pHl.7-2.0, but other optimized cultural conditions, such as temperature, aeration, and so on, were similar.The specific growth rate of adapted At. ferrooxidans cells was 0.0635 1/h, which was similar to the original bacterium too. Considering the structure and mechanical strength of carriers, polyvinyl alcohol gel was selected as the matrix for At. ferrooxidans immobilization, and the immobilization procedure was also determined by experiments. Two different immobilized At. ferrooxidans, termed PVA-boric acid gel and PVA-cryogel correspondingly, were obtained by PVA-boric acid method and iterative freezing and thawing method respectively, both entrapping about 109 cells of At. ferrooxidans per ml of gel. (3)The effects of temperature and pH on the biooxidation of ferrous iron by PVA-boric acid gel and PVA cryogel immobilized At. ferrooxidans were investigated respectively. The results showed that the optimum temperature and pH for biooxidation of ferrous irons by immobilized cells were similar to those of free cells. The kinetic research on biooxidation of ferrous irons by immobilized At. ferrooxidans cells in two 365ml parallel packed-bed bioreactors showed that At. ferrooxidans cells immobilized with PVA by iterative freezing and thawing method were better than those of PVA-boric acid method for ferrous iron oxidation, their kinetic constant for biooxidation of ferrous iron were 0.6 L/L/h and 0.4 L/L/h respectively at the ferrous iron concentration of 8g/L, and an inhibitory effect of high ferrous iron concentration on the activity of PVA-cryogel immobilized cells was clearly observed. (4)The feasibility of chemical leaching of sulfide ores by acid ferric iron solution was proven by experiments, in which the low-grade nickel-copper sulfide ores obtained from Jinchuan, the copper sulfide ores obtained from Dongxiang county of Jiangxi province, and a kind of artificially synthetic copper sulfide ores were leached by ferric iron solution via agitated tank-leachng and dump-leaching respectively, the leaching reactions in the acid ferric iron solution were either chemically controlled processes, or diffusion controlled processes, or both of them, according to the mineral structure and leaching way. Though the leaching was influenced by the ferric iron concentration, temperature and acidity of acid ferric iron solution, the leaching efficiency was better than the direct leaching with free At. ferrooxidans cells. (5)A novel technology of sulfide ore chemical leaching by acid ferric iron solution coupled with biooxidation of ferrous iron by PVA-cryogel immobilized At. ferrooxidans was developed, hereby a low-grade nickel-copper sulfide ores obtained from Jinchuan was leached continuously at the dilution rate of 0.2 1/h in a packed-bed bioreactor for ferrous iron oxidation. The leached fractions of nickel and copper reached 82.3% and 65.9% respectively after 24 h continuous stirred tank-leaching of the ores with —300 mesh and the concentration of 5% at 70 °C, while the leaching fractions were 87.3% and 51.3% correspondingly after 39 days of continuous column leaching of the ores with -20 mesh + 40 mesh at room temperature. (6) A kinetic model was constructed to simulate the integration of the chemical leaching of sulfide ores and the biooxidation of ferrous iron by immobilized At. ferrooxidans. The coupling technology superiorities were analyzed, and its imperfections were discussed as well. |
| 语种 | 中文 |
| 公开日期 | 2013-09-16 |
| 页码 | 183 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1398]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 龙中儿. 氧化亚铁硫杆菌的固定化及其在矿物浸出中的应用研究[D]. 中国科学院过程工程研究所. 中国科学院过程工程研究所. 2003. |
入库方式： OAI收割
来源：过程工程研究所
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