嗜鐵鉤端螺旋菌的篩選及其礦石黏附特性的研究
發(fā)布時間：2018-08-27 11:58
【摘要】：我國作為一個產(chǎn)金大國,金礦資源儲量比較豐富,生物冶金技術(shù)已經(jīng)廣泛應(yīng)用于難處理金礦的處理中。其中冶金菌株的種類繁多,此前氧化亞鐵硫桿菌{Thiobacillus ferrooxidans)直被認(rèn)為是生物冶金中的主要菌株,后來人們發(fā)現(xiàn)40℃冶金過程中鉤端螺旋菌為優(yōu)勢鐵氧化細(xì)菌,工業(yè)運(yùn)用中鉤端螺旋菌作為優(yōu)勢菌株往往與其它菌株混合使用,對純菌株的研究較少。目前,鉤端螺旋菌的篩選存在著較大問題,嚴(yán)重影響了針對鉤端螺旋菌的研究進(jìn)程。本文通過總結(jié)前人的研究成果,改進(jìn)了雙層平板分離方法,從酸性礦山廢水(AMD)中分離出冶金菌株并鑒定,隨后利用分離株進(jìn)行浸礦試驗(yàn),探索溫度、初始pH以及接種量對該菌株氧化難處理含金黃鐵礦的影響；進(jìn)一步研究了生物氧化過程中嗜鐵鉤端螺旋菌的對礦石顆粒的黏附特性,以及鈍化層對生物氧化過程效率的影響關(guān)系。本文從AMD中篩選獲得了8株鐵氧化細(xì)菌,其中5株對難處理含金黃鐵礦有著較好的氧化效果,分別通過形態(tài)學(xué)研究、生理生化試驗(yàn)、16S rRNA序列分析和系統(tǒng)發(fā)育樹等方法鑒定了其中氧化效果最佳的一株分離株,并命名為嗜鐵鉤端螺旋菌(Leptospirillum ferriphilum) LJ-02。通過單因素?fù)u瓶實(shí)驗(yàn),分別對Leptospirillum ferriphilum LJ-02氧化難處理含金黃鐵礦過程的溫度、初始pH以及接種量等操作條件進(jìn)行了考察,并采用了經(jīng)典的Hansford邏輯方程對各操作條件下的礦石氧化性能進(jìn)行擬合和分析。實(shí)驗(yàn)發(fā)現(xiàn),溫度在36-46℃范圍內(nèi),難處理含金黃鐵礦的礦石氧化率呈現(xiàn)出先升后降的趨勢,溫度在41℃時達(dá)到礦石最大氧化率。降低pH對提高細(xì)菌氧化能力有著顯著影響,綜合考慮,將初始pH調(diào)節(jié)為1.4為細(xì)菌氧化難處理含金黃鐵礦的最佳pH。提高接種量有利于難處理含金黃鐵礦的生物氧化,但接種量超過10%(v/v)后作用減弱。上述結(jié)果表明,溫度41℃、初始pH 1.4以及10%(v/v)的接種量是Leptospirillum ferriphilum LJ-02氧化難處理含金黃鐵礦較為適宜的條件。采用專門設(shè)計的搖瓶試驗(yàn),考察了Leptospirillum ferriphilum LJ-02對難處理含金黃鐵礦氧化過程中的黏附特性,同時也探索了菌體黏附與生物氧化過程效率之間的關(guān)系。實(shí)驗(yàn)發(fā)現(xiàn),菌體黏附于難處理含金黃鐵礦后迅速發(fā)生生物氧化,當(dāng)菌體不能黏附難處理含金黃鐵礦時,難處理含金黃鐵礦是以化學(xué)浸出為主。掃描電鏡結(jié)果顯示,Leptospirillum ferriphilum LJ-02在生物氧化時確實(shí)黏附在難處理含金黃鐵礦表面,浸礦后難處理含金黃鐵礦表面變得粗糙,充滿褶皺,并且在表面形成了許多“蟲洞”。通過線性相關(guān)性分析分別比較了不同溫度、不同pH等條件下,黏附率和礦石氧化率的相關(guān)性,發(fā)現(xiàn)不同溫度下黏附率與礦石氧化率是高度相關(guān)的,不同pH下黏附率與礦石氧化率是顯著性相關(guān)的。研究發(fā)現(xiàn)氧化過程中在礦石表面逐漸形成的鈍化層對Leptospirillum ferriphilumLJ-02氧化難處理含金黃鐵礦的生物氧化效率具有負(fù)面影響,實(shí)驗(yàn)中通過用清洗液處理浸礦礦渣可以去除礦渣表面部分的鈍化層,礦渣經(jīng)過清洗后進(jìn)行生物氧化反應(yīng),其浸出液的Fe3+終濃度將達(dá)到7.2g/L,而未經(jīng)過清洗的礦渣浸礦實(shí)驗(yàn)后浸出液中的Fe3+的終濃度僅僅為3.96g/L,清洗礦渣后礦石的氧化率提高了81.82%,清洗過的難處理含金黃鐵礦礦渣表面Leptospirillum ferriphilum LJ-02的黏附率是未經(jīng)清洗礦渣的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.
【學(xué)位授予單位】：華東理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TD925.5
本文編號：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.
【學(xué)位授予單位】：華東理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TD925.5
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