Decomposition mechanism of pentlandite during electrochemical bio-oxidation process  

镍黄铁矿电化学生物氧化过程的分解机理(英文)

作　　者：李宏煦[1,2] 李超[1,2] 张祉倩[1,2] 

机构地区：[1]北京科技大学冶金与生态工程学院,北京100083 [2]北京科技大学教育部生态与循环冶金重点实验室,北京100083

出　　处：《Transactions of Nonferrous Metals Society of China》2012年第3期731-739,共9页中国有色金属学报（英文版）

基　　金：Project(20876014) supported by the National Natural Science Foundation of China

摘　　要：Electrochemical measurements were carried out to elucidate decomposition mechanism of pentlandite using modified powder microelectrode with Acidithiobacillus ferrooxidans attached or without on the mineral powder surface.Cyclic voltammetry（CV） results show that at a low potential of about-0.2 V（vs SCE）,the pentlandite was transformed to an intermediated phase like Fe4.5-yNi4.5-xS8-z when Fe and Ni ions were evacuated from mineral lattice;when the potential was changed from-0.2 V to 0.2 V,the unstable violarite（Fe3Ni3S4） and FeNi2S4 were formed which was accompanied by element sulfur formed on the mineral surface;when the potential increased over 0.2 V,the unstable intermediated phase decomposed entirely;at a higher potential of 0.7 V,the evacuated ferrous ion was oxidized to ferric ion.The presence of Acidithiobacillus ferrooxidans made the oxidation peak current increase with initial peak potential negatively moving,and the bacteria also contributed to the sulfur removing from mineral surface,which was demonstrated by the reduction characteristic at potential ranging from-0.75 to-0.5 V.Leaching experiments and electrochemical results show that the solution acidity increasing when pH2 may impede the oxidation process slightly.应用表面粘附和没有粘附Acidithiobacillus ferrooxidans的镍黄铁矿粉末微电极进行电化学测试,以说明镍黄铁矿氧化分解的机理。循环伏安CV结果显示,在-0.2V的低电位区域,在镍、铁离子析出时镍黄铁矿转变为中间相Fe4.5-yNi4.5-xS8-z;当电位在-0.2V到0.2V区间时,有不稳定的紫硫镍矿Fe3Ni3S4和FeNi2S4形成并在表面伴有元素硫的产生;当电位增加到0.2V以上时,不稳定相将全部分解;在高电位0.7V时,析出的亚铁离子被氧化为高铁离子。嗜酸氧化亚铁硫杆菌Acidithiobacillus ferrooxidans的存在使峰电位增高,反应起始电位负移,并对表面形成的元素硫有氧化去除作用。这一过程可通过-0.75到-0.5V电位区间发生的的还原反应证实。生物浸出和电化学实验结果均表明当pH<2时溶液酸度的增加对氧化过程有轻度的阻碍作用。

关 键 词：PENTLANDITE Acidthiobacillus ferrooxidans BIOLEACHING powder modified microelectrode 

分 类 号：TF801[冶金工程—有色金属冶金]