嗜铁钩端螺旋菌的筛选及其矿石黏附特性的研究
发布时间：2018-08-27 11:58
【摘要】：我国作为一个产金大国,金矿资源储量比较丰富,生物冶金技术已经广泛应用于难处理金矿的处理中。其中冶金菌株的种类繁多,此前氧化亚铁硫杆菌{Thiobacillus ferrooxidans)直被认为是生物冶金中的主要菌株,后来人们发现40℃冶金过程中钩端螺旋菌为优势铁氧化细菌,工业运用中钩端螺旋菌作为优势菌株往往与其它菌株混合使用,对纯菌株的研究较少。目前,钩端螺旋菌的筛选存在着较大问题,严重影响了针对钩端螺旋菌的研究进程。本文通过总结前人的研究成果,改进了双层平板分离方法,从酸性矿山废水(AMD)中分离出冶金菌株并鉴定,随后利用分离株进行浸矿试验,探索温度、初始pH以及接种量对该菌株氧化难处理含金黄铁矿的影响；进一步研究了生物氧化过程中嗜铁钩端螺旋菌的对矿石颗粒的黏附特性,以及钝化层对生物氧化过程效率的影响关系。本文从AMD中筛选获得了8株铁氧化细菌,其中5株对难处理含金黄铁矿有着较好的氧化效果,分别通过形态学研究、生理生化试验、16S rRNA序列分析和系统发育树等方法鉴定了其中氧化效果最佳的一株分离株,并命名为嗜铁钩端螺旋菌(Leptospirillum ferriphilum) LJ-02。通过单因素摇瓶实验,分别对Leptospirillum ferriphilum LJ-02氧化难处理含金黄铁矿过程的温度、初始pH以及接种量等操作条件进行了考察,并采用了经典的Hansford逻辑方程对各操作条件下的矿石氧化性能进行拟合和分析。实验发现,温度在36-46℃范围内,难处理含金黄铁矿的矿石氧化率呈现出先升后降的趋势,温度在41℃时达到矿石最大氧化率。降低pH对提高细菌氧化能力有着显著影响,综合考虑,将初始pH调节为1.4为细菌氧化难处理含金黄铁矿的最佳pH。提高接种量有利于难处理含金黄铁矿的生物氧化,但接种量超过10%(v/v)后作用减弱。上述结果表明,温度41℃、初始pH 1.4以及10%(v/v)的接种量是Leptospirillum ferriphilum LJ-02氧化难处理含金黄铁矿较为适宜的条件。采用专门设计的摇瓶试验,考察了Leptospirillum ferriphilum LJ-02对难处理含金黄铁矿氧化过程中的黏附特性,同时也探索了菌体黏附与生物氧化过程效率之间的关系。实验发现,菌体黏附于难处理含金黄铁矿后迅速发生生物氧化,当菌体不能黏附难处理含金黄铁矿时,难处理含金黄铁矿是以化学浸出为主。扫描电镜结果显示,Leptospirillum ferriphilum LJ-02在生物氧化时确实黏附在难处理含金黄铁矿表面,浸矿后难处理含金黄铁矿表面变得粗糙,充满褶皱,并且在表面形成了许多“虫洞”。通过线性相关性分析分别比较了不同温度、不同pH等条件下,黏附率和矿石氧化率的相关性,发现不同温度下黏附率与矿石氧化率是高度相关的,不同pH下黏附率与矿石氧化率是显著性相关的。研究发现氧化过程中在矿石表面逐渐形成的钝化层对Leptospirillum ferriphilumLJ-02氧化难处理含金黄铁矿的生物氧化效率具有负面影响,实验中通过用清洗液处理浸矿矿渣可以去除矿渣表面部分的钝化层,矿渣经过清洗后进行生物氧化反应,其浸出液的Fe3+终浓度将达到7.2g/L,而未经过清洗的矿渣浸矿实验后浸出液中的Fe3+的终浓度仅仅为3.96g/L,清洗矿渣后矿石的氧化率提高了81.82%,清洗过的难处理含金黄铁矿矿渣表面Leptospirillum ferriphilum LJ-02的黏附率是未经清洗矿渣的1.38倍。
[Abstract]:As a large gold-producing country, China has abundant gold resources, and bio-metallurgical technology has been widely used in the treatment of refractory gold deposits. Among them, there are many kinds of metallurgical bacteria. Thiobacillus ferrooxidans has been considered as the main strain in bio-metallurgy before, and then people discovered the metallurgical process at 40 C. Leptospira intermedia is a predominant iron-oxidizing bacteria. In industrial application, Leptospira intermedia is often used as a predominant strain in combination with other strains, and there is little research on pure strains. Metallurgical strains were isolated from acid mine wastewater (AMD) and identified by improved double-layer plate separation method. Then leaching tests were carried out with the strains to explore the effects of temperature, initial pH and inoculation amount on the oxidation of refractory gold-bearing pyrite by the strains. Eight strains of iron-oxidizing bacteria were screened from AMD. Five of them had good oxidation effect on refractory gold-bearing pyrite. They were identified by morphological, physiological and biochemical tests, 16S rRNA sequence analysis and phylogenetic tree analysis. A strain of Leptospirillum Ferriphilum LJ-02 with the best oxidation effect was isolated and named as Leptospirillum Ferriphilum LJ-02. The temperature, initial pH and inoculation amount of the oxidation process of refractory pyrite containing gold in Leptospirillum Ferriphilum LJ-02 were investigated by single factor shaking flask test. The results show that the oxidation rate of refractory gold-bearing pyrite ore increases first and then decreases in the range of 36-46 C, and reaches the maximum oxidation rate at 41 C. When the initial pH was adjusted to 1.4, the best pH for bacterial oxidation of refractory gold-bearing pyrite was obtained. Increasing inoculation amount was beneficial to the biological oxidation of refractory gold-bearing pyrite, but the effect was weakened after inoculation amount exceeded 10%(v/v). The above results showed that the inoculation amount of Leptospirillum Ferriphilum LJ-02 oxygen was 41 C, initial pH 1.4 and 10%(v/v). The adhesion characteristics of Leptospirillum Ferriphilum LJ-02 to refractory gold-bearing pyrite during oxidation were investigated by a specially designed shaking flask test. The relationship between bacterial adhesion and bio-oxidation efficiency was also explored. The results of scanning electron microscopy show that Leptospirillum Ferriphilum LJ-02 does adhere to the surface of refractory gold-bearing pyrite during bio-oxidation, and the surface of refractory gold-bearing pyrite changes after leaching. It is rough, full of folds and forms many "wormholes" on the surface. By linear correlation analysis, the correlation between adhesion rate and oxidation rate of ore at different temperatures and pH is compared. It is found that adhesion rate and oxidation rate of ore at different temperatures are highly correlated, and adhesion rate and oxidation rate of ore at different pH are significant. It is found that the passivation layer formed on the surface of ore during oxidation has a negative effect on the bio-oxidation efficiency of refractory gold-bearing pyrite oxidized by Leptospirillum Ferriphilum LJ-02. In the experiment, the passivation layer on the surface of slag can be removed by treating the leaching slag with cleaning solution, and the slag can be regenerated after cleaning. The final concentration of Fe3+ in the leaching solution will reach 7.2 g/L by oxidation reaction, while the final concentration of Fe3+ in the leaching solution is only 3.96 g/L after the experiment of non-cleaning slag leaching. The oxidation rate of ore after cleaning slag is increased by 81.82%. The adhesion rate of Leptospirillum Ferriphilum LJ-02 on the surface of refractory gold-bearing pyrite slag after cleaning is not found. 1.38 times of cleaning slag.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD925.5
本文编号：2207210
[Abstract]:As a large gold-producing country, China has abundant gold resources, and bio-metallurgical technology has been widely used in the treatment of refractory gold deposits. Among them, there are many kinds of metallurgical bacteria. Thiobacillus ferrooxidans has been considered as the main strain in bio-metallurgy before, and then people discovered the metallurgical process at 40 C. Leptospira intermedia is a predominant iron-oxidizing bacteria. In industrial application, Leptospira intermedia is often used as a predominant strain in combination with other strains, and there is little research on pure strains. Metallurgical strains were isolated from acid mine wastewater (AMD) and identified by improved double-layer plate separation method. Then leaching tests were carried out with the strains to explore the effects of temperature, initial pH and inoculation amount on the oxidation of refractory gold-bearing pyrite by the strains. Eight strains of iron-oxidizing bacteria were screened from AMD. Five of them had good oxidation effect on refractory gold-bearing pyrite. They were identified by morphological, physiological and biochemical tests, 16S rRNA sequence analysis and phylogenetic tree analysis. A strain of Leptospirillum Ferriphilum LJ-02 with the best oxidation effect was isolated and named as Leptospirillum Ferriphilum LJ-02. The temperature, initial pH and inoculation amount of the oxidation process of refractory pyrite containing gold in Leptospirillum Ferriphilum LJ-02 were investigated by single factor shaking flask test. The results show that the oxidation rate of refractory gold-bearing pyrite ore increases first and then decreases in the range of 36-46 C, and reaches the maximum oxidation rate at 41 C. When the initial pH was adjusted to 1.4, the best pH for bacterial oxidation of refractory gold-bearing pyrite was obtained. Increasing inoculation amount was beneficial to the biological oxidation of refractory gold-bearing pyrite, but the effect was weakened after inoculation amount exceeded 10%(v/v). The above results showed that the inoculation amount of Leptospirillum Ferriphilum LJ-02 oxygen was 41 C, initial pH 1.4 and 10%(v/v). The adhesion characteristics of Leptospirillum Ferriphilum LJ-02 to refractory gold-bearing pyrite during oxidation were investigated by a specially designed shaking flask test. The relationship between bacterial adhesion and bio-oxidation efficiency was also explored. The results of scanning electron microscopy show that Leptospirillum Ferriphilum LJ-02 does adhere to the surface of refractory gold-bearing pyrite during bio-oxidation, and the surface of refractory gold-bearing pyrite changes after leaching. It is rough, full of folds and forms many "wormholes" on the surface. By linear correlation analysis, the correlation between adhesion rate and oxidation rate of ore at different temperatures and pH is compared. It is found that adhesion rate and oxidation rate of ore at different temperatures are highly correlated, and adhesion rate and oxidation rate of ore at different pH are significant. It is found that the passivation layer formed on the surface of ore during oxidation has a negative effect on the bio-oxidation efficiency of refractory gold-bearing pyrite oxidized by Leptospirillum Ferriphilum LJ-02. In the experiment, the passivation layer on the surface of slag can be removed by treating the leaching slag with cleaning solution, and the slag can be regenerated after cleaning. The final concentration of Fe3+ in the leaching solution will reach 7.2 g/L by oxidation reaction, while the final concentration of Fe3+ in the leaching solution is only 3.96 g/L after the experiment of non-cleaning slag leaching. The oxidation rate of ore after cleaning slag is increased by 81.82%. The adhesion rate of Leptospirillum Ferriphilum LJ-02 on the surface of refractory gold-bearing pyrite slag after cleaning is not found. 1.38 times of cleaning slag.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD925.5
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