【作者】 李宏煦；

【导师】 王淀佐； 邱冠周； 胡岳华；

【作者基本信息】 中南大学 ， 矿物加工， 2001， 博士

【摘要】 本文系统研究了Fe²⁺离子的氧化与T.f菌生长规律，单一及混合硫化矿、大宝山实际铜矿物细菌浸出的工艺及浸出过程机理。运用T.f菌修饰粉末微电极方法对T.f菌氧化Fe²⁺的机理及硫化矿细菌浸出过程的电化学机理及动力学进行了较为系统的研究。 循环伏安、稳态极化法、暂态电位阶跃等方法研究表明，Fe²⁺T.f菌修饰碳粉粉末微电极上的氧化是一可逆反应。Fe²⁺在Tf茵修饰粉末微电极上稳态极化极限扩散电流为i_L=1.85e^-6Am·cm^-2，以此计算的电荷扩散系数为6.25×10^-6cm²·s^-1。循环伏安法研究表明，i_P与υ^1/2关系为二次曲线，但Δ（?）_P^′，与υ为线性关系。对于快速扫描过程，通过T.f菌修饰粉末微电极上的电流为微盘电流与薄层电流之和。当[Cu²⁺]在0.015mol·dm^-3以下时，Cu²⁺的存在不会抑制Fe²⁺在T.f菌修饰粉末微电极上的氧化，且在0.004～0.012mol·dm^-3范围内，Cu²⁺的存在会使电极反应电荷扩散系数增大，对Fe²⁺的氧化有加强作用。当pH在1.5～2.5之间，[Fe²⁺]在0.22mol·dm^-3以下变动时，电极反应的可逆程度不变，且证明在pH为2、·[Fe²⁺]为0.16mol·dm_³时T.f菌氧化Fe²⁺的活性最强。电位阶跃计时电流、计时电位法与稳态极化法求得的电荷扩散系数基本相同。设计了T.f菌生长电化学池，利用开路电压值及阴阳极电解液中[Fe³⁺]/[Fe²⁺]关系导出了计算T.f菌电池输出电压的数学表达式；并建立了反映Tf菌生长速率的动力学方程，实验值与由动力学方程所得的计算值符合较好。 基于粉末微电极可体现短暂的中间反应过程的特征，循环伏安法研究认为，黄铁矿、黄铜矿、CuS、镍黄铁矿的阳极氧化分解过程均由多步反应组成。T.f菌的加入使阳极反应成一连续过程，反应峰电流增加，峰电位负移，反应的可逆性增强，且对中间生成的元素硫有氧化作用。Fe³⁺的加入、pH的降低亦可使硫化矿阳极氧化峰区域加宽，电流增加，反应可逆性增强。pH的变化对镍黄铁矿的阳极过程有复杂影响。 半导体电化学分析认为，黄铁矿的氧化是基于半导体与溶液间空穴转移的反应，黄铜矿、铜蓝、镍黄铁矿初始反应为空穴的消耗，随之有电子转移。T.f菌的存在使溶液中Fe²⁺氧化为Fe³⁺，从而使溶液中空穴数量增加，氧化电位上升，溶液费米能级更接近于价带，空穴转移速度加快，反应加剧。 动力学研究认为，细菌存在时，黄铁矿、黄铜矿、镍黄铁矿阳极氧化过程为电化学反应与扩散混合控制，铜蓝的氧化则主要以扩散控制为主。根据粉末微电极Tafel曲线求得，细菌的加入使黄铁矿、黄铜矿、镍黄铁矿腐蚀电位降低腐蚀电流升高，反应加速。结果表明，混合矿腐蚀电流较单一矿高。运用电位阶跃法测得了铜蓝、黄铁矿、黄铜矿、镍黄铁矿阳极过程的电荷扩散系数及反应速率常数。测定了黄铁矿与黄铜矿、镍黄铁矿混合粉末微电极阳极过程的各动力学参数，并得到了相应的动力学方程，混合矿浸出结果进一步证明了混合矿细菌浸出过程的原电池效应。单一矿浸出显示在有氧酸性体系，黄铁矿会不断氧化分解，浸出体系pH不断下降，而黄铜矿、镍黄铁矿的浸出对pH的贡献不大，浸出体系pH的下降主要是因为黄铁矿氧化分解所致。 扫描电镜（SME）及表面EDS能谱研究证实了混合电位效应对硫化细菌矿浸出的作中南大学博士学位论文 硫化矿细菌浸出过程的电化学机理及工艺研究用。浸出前后表面原子数比例显示黄铁矿浸出过程中表面不会生成元素S’膜，而黄铜矿、镍黄铁矿表面会生成 s’，元素 s‘膜会阻碍黄铜矿进一步氧化分解，但并不影响镍黄铁矿中Ni的浸出，细菌对 S’的氧化会促进黄铜矿的进一步氧化溶解。 应用大宝山铜矿物进行了实际矿物细菌浸出实验，证明大宝山铜矿适合细菌浸出提铜。实际腑中黄栅的存在赡出过程洲逐步下降，不需补充过多的酸以保证龊。溶液中Na＋等半径较大的阳离子的存在会加速铁钒的生成，阻碍铜的浸出，竹的存在会大大加速铜的浸出。部分会在矿山天然形成的有机物或苹余液中的有机物会阻碍铜的细菌氧化浸出，阻碍作用大小依次为：EDTA＞羟函＞单宁腐植酸。更多还原

【Abstract】 In this paper, the fundamental and technological investigations about roles of the oxidation of Fe*and increment of T. ferrooxidans have been proceeded as well as the bio條eaching of sulf ide .. mixed sulf ide and Da BaoShan’ s copper ore. The electrochemistry mechanisms of the Fe1* oxidation and sulf ide anode behavior were studied using T. ferrooxidans modified and un-modified powder microelectrode in acid solution systematically.Cyclic votalmmetry, steady potentiodynamic, transient potential stair-step measurement show that the oxidation on the T. ferrooxidans modified carbon powder microelectrode is a reversibility reaction. The unti-diffusion current is 1. SSe^Am. cm"2. By calculation we get the charge diffusion coefficient is 6.25X lO^cm2. s"1. From CV curve we know that the relationship between ipand u12 is a quadric curve. Further more, the Acpp’ is liner with u. To quick scan speed, the current晅hrough the T. ferrooxidans modified carbon powder microelectrodeinclude the micro-disc and thin layer current. When the concentration of Cu^under 0. OlSrool. dm"3, even if it varies from 0. 004mol. dnf3to 0. 012mol. dm"3, the presence of Cu^could increase the charge diffusion coefficient, rather than inhibit the Fe2* oxidation. When the electrolyte PH at 1.5-~2.5 and [Fe2*] under 0.16 mol. dm"3, the variation of pH and [Fe2*] can not change the reversibility of the electrode process. It demonstrates that the effect of T. ferrooxidans on the Fe2* oxidation is more active at pH 2 and [Fe2l 0.16mol. dm"3.The T. ferrooxidans bath culture bio-cell is designed. The dynamic equations about the output voltage of bio-cell and the growth of T. ferrooxidans are proposed by utilization of calculation and measuring valve about voltage, [Fe2*] and [Fe3*] concentration. The calculated results using dynamic equation are well consistence with the measurements.Based on the character of powder micro-electrode, which could detect the transient reaction process, the intermediate reactions of the anode process of pyrite^chalcopyrite>covelite,pentlandite,which could not be detected using common electrode are measured by CV test. When the T. ferrooxidans in presence as well as in the presence of Fe3* and the decreasing of pH , the anode process of sulf ide are the successive reactions, company with the peak current and reversibility of reaction increasing, the peak potential negatively moving and the peak area expanding. The T. ferrooxidans has contribution to the oxidation of element sulfur formatted during the intermediate process. The pH has complex effect on the pentlandite anode process.The semiconductor electrochemistry investigate demonstrate that the pyrite is oxidized by the transfer of holes between semiconductor and solution surface, but to chalcopyrite, covelite and penlandite, in the initial time is by the holes transfer, then company with the electron transfer.The dynamic study show that the anode behavior of pyrite, chalcopyrite and penlandite is a mixed control process by electro- chemical reaction and charge diffusion, but to the covelite, charge diffusion is the main control factor. The polarize Tafel curve prove that the addition of T. ferrooxidans can makes the corrosion potential of sulfide decrease , the exchange current increase and the oxidation rate is accelerated. From the potential step-stair measurement, the charge diffusion coefficient and the reaction velocity constant of the anode process of individual and mixed sulfide are acquired. The results show that the corrosion current of the mixed sulfide is higher than that of the individual one. The results of leaching for the mixed sulfide certify the galvanic effect in the processing of the bio- leaching. The leaching for the individual sulfide show that the pyrite will be decomposed continuously company with the decrease of the pH, but the chalcopyrite and pentlandite has little contribution to the decrease of pH.The scan electron microscope and surface electron probe method verify the mixed potential effect in the sulfide bio-leachin更多还原