The Mechanism and Kinetics of Bioleaching Sulphide Minerals

Abstract

The measurement of oxygen and carbon dioxide consumption rates together with the measurement of redox potentials, has led to the further elucidation of the mechanism of bioleaching of sulphide minerals and enabled the kinetics of the sub-processes involved to be determined separately. This has shown that the primary attack of the sulphide mineral is a chemical ferric leach with the role of the bacteria to re-oxidise the ferrous iron formed back to the ferric form and maintain a high redox potential as well as oxidising the elemental sulphur which is formed in some cases. The kinetics of bacterial ferrous oxidation by Thiobacillus ferrooxidans and Leptospirillum ferrooxidans have been determined over a range of expected operating conditions. Also the chemical ferric leach kinetics of pyrite have been measured under conditions similar to those in bioleach systems. The kinetics have been described as functions of the ferric/ferrous-iron ratio or redox potential which enables the interactions of the two sub-processes to be linked at a particular redox potential through the rate of ferrous iron turn-over. The use of these models in predicting bioleach behaviour for pyrite presented and discussed. The model is able to predict which bacterial species will predominate at a particular redox potential in the presence of a mineral, and which mineral will be preferentially leached. The leach rate and steady state redox potential can be predicted from the bacterial to mineral ratio. The implications of this model on bioleach reactor design and operation are discussed.     

黄铁矿生物氧化过程的阶段性

以氧化亚铁硫杆菌为实验菌株，研究了黄铁矿的Fe³⁺氧化和生物氧化过程中溶液铁离子浓度、pH值以及Eh值的变化。结果表明，Fe³⁺由于自身很快会被消耗，因而对黄铁矿的氧化速率较低；而在细菌的作用下，Fe²⁺可以不断被氧化成Fe³⁺，从而使黄铁矿的氧化速率明显加快，因此生物氧化具有更高的效率。基于间接作用机制，结合黄铁矿生物氧化过程中pH值及Eh值的变化规律，提出了黄铁矿生物氧化的阶段性特点，即将氧化亚铁硫杆菌对黄铁矿的氧化过程分为黄铁矿无机氧化、Fe²⁺生物氧化和黄铁矿稳定生物氧化3个阶段。     

脱硫菌培养条件及脱硫研究

介绍了pH值、培养时间和接种量对氧化亚铁硫杆菌生长的影响。测定该菌对煤炭脱硫效果的结果表明，在9K培养基初始pH=2、接种量15%的情况下，氧化亚铁硫杆菌生长5 d后浓度达108个/mL，10 d后黄铁矿脱除率达到52.29%,全硫脱除率达到37.75%。     

氧化亚铁硫杆菌胞外多聚物的研究进展

介绍关于氧化亚铁硫杆菌胞外多聚物的组成、生成影响因素、其在氧化亚铁硫杆菌吸附到矿物表面的过程中所起作用等方面的研究进展，并对今后的研究做出一些建议。     

氧化亚铁硫杆菌在硫化矿物表面的吸附

研究了氧化亚铁硫杆菌在黄铁矿、黄铜矿、方铅矿和闪锌矿表面的吸附情况,结果表明,氧化亚铁硫杆菌在4种硫化矿物表面的吸附无明显选择性;溶液初始pH值对氧化亚铁硫杆菌在4种硫化矿物表面的吸附几乎无影响,但酸性环境有利于吸附的发生;细胞悬浮液浓度为0.1～1.0 g/L、矿浆浓度为15 g/L以上和温度为20～30 ℃是氧化亚铁硫杆菌在4种硫化矿物表面吸附的较适宜条件。扫描电子显微镜检测结果显示,氧化亚铁硫杆菌细胞表面的荚膜是重要的吸附位。红外光谱分析结果表明,氧化亚铁硫杆菌细胞表面含有-OH、-NH₂、C=O、C-O等活性基团,它们在吸附过程中起重要作用。     

金川低品位镍矿资源微生物浸出研究

金川低品位镍矿资源———贫矿和尾矿具有良好的生物可浸性 ,尾矿比贫矿更容易浸出。采用以氧化亚铁硫杆菌为主的混合浸矿菌株浸出金川尾矿 ,镍、铜、钴浸出率分别可达 87 84%、84 0 5 %和86 35 % ;贫矿细菌浸出 ,镍、铜、钴的浸出率分别达到 88 78%、47 68%和 65 65 %。针对金川矿石碱性脉石多 ,导致普通T·f菌浸出过程中耗酸量大、pH值不稳的特点 ,采用诱变技术选育了耐高pH值的浸矿菌株。该菌株应用于金川尾矿和贫矿浸出 ,浸出指标接近普通T·f菌浸出指标 ,为金川低品位资源生物浸出工业化应用奠定了良好的基础     

鄂西鲕状高磷赤铁矿微生物脱磷研究

研究利用嗜酸氧化亚铁硫杆菌(At.f菌)和嗜酸氧化硫硫杆菌(At.t菌)的协同作用从鄂西鲕状高磷赤铁矿中脱磷的主要影响因素。研究结果表明,At.t菌与At.f菌按照接种量为2∶1混合后,其脱磷率达到了88.7%,同时在不同矿浆初始pH值和矿浆浓度的试验条件下发现,在pH=1.8～2.5条件下,细菌脱磷能力较强,而矿浆浓度超过5%时对细菌脱磷具有明显抑制作用。     

脱氮硫杆菌ATCC25259 SQR蛋白及突变体的结构分析与活性研究

本文研究了通过Discovery Studio 3.5利用同源建模法构建了脱氮硫杆菌ATCC25259的硫化物:醌氧化还原酶(Sulfide:quinone oxidoreductase,SQR)野生型蛋白及突变体蛋白模型,通过GROMACS 5.1.2对所有模型进行分子力学及分子动力学的优化,使蛋白模型处于能量较低且结构稳定的状态。使用PROCHECK,Verify 3D和Pro SA三种模型评价方法对模型进行评价,表明蛋白模型具有较高的合理性。使用该蛋白模型计算蛋白相互作用、SAS及能量值。将构建好的SQR及突变体的表达载体转入大肠杆菌BL21(DE3)诱导表达分子量约65 ku的蛋白。使用镍柱亲和层析纯化经大量表达含有6×His标签的野生型与突变体蛋白,采用已经建立的SQR活性测定方法,进行酶活性测定实验,结果表明突变体酶活性较低。从模拟计算与实验验证两方面说明SQR C端α螺旋结构对蛋白的结构稳定性具有重要影响,蛋白结构稳定性降低,从而酶活性降低。     

Preparation ofjarosite by Acidithiobacillus ferrooxidans oxidation

The formation of jarosite in the presence of Acidithiobacillus ferrooxidans (A. ferrooxidans) was researched to ascertain the conditions of producing minimum precipitation. The effects of salt concentration and pH on the characteristics of jarosite formed in K2SO4/(NH4)2SO4-FeSO4 inorganic salt solution and 9K medium were studied by using the measurements of scanning electron microscope, X-ray diffraction, Fourierism transform infrared analysis, thermogravity/differential thermogravity analysis and particle size analysis to evaluate the product. The results indicate that the formation of jarosite begins when A. ferrooxidans reaches logarithmic growth phase in 9K medium, and a higher pH value is beneficial to the formation of jarosite. The jarosite formed in 9K medium has smaller and more concentrative particle size and smoother surface than that formed in inorganic salt solution.     

生化法二氧化硫脱除条件的确认

生化法脱硫中,借助氧化亚铁硫杆菌的新陈代谢作用,维持吸收液Fe3+浓度,获得稳定脱硫效率,实验证实,吸收液pH值、Fe3+浓度、氧化亚铁硫杆菌菌量、液气比和吸收液体积对脱硫效率影响较大.当pH值为2.5～3.0时,脱硫效率最高,且与微生物繁殖增长最佳pH值相近;当[Fe3+]＞ 300 mg/L,加菌量超过10 mL,...