氧化亚铁硫杆菌对酸化铅锌尾矿中Zn、As淋溶释放的影响

Influence on leaching of zinc and arsenic in acidified lead-zinc tailings by Acidithiobacillus ferrooxidans

以青海某铅锌尾矿为研究对象进行酸预处理加速模拟静态淋溶实验,重点研究了氧化亚铁硫杆菌(At.f菌)接种量变化对尾矿中重金属Zn、As迁移释放的影响。结果表明,随时间延长,接种量变化均可导致淋溶体系pH值下降、电导率上升,氧化还原电位先上升后下降。At.f菌可明显促进Zn、As的释放,不同接种量对重金属的迁移释放作用不同;At.f菌存在下,Zn的释放能力大于As,Zn优先于As溶出,Zn、As浓度均表现为快速释放和缓慢释放并趋于平稳两个阶段,Evolich模型和Guass模型可分别描述Zn、As的释放过程。通过对细菌淋溶前后残渣SEM-EDS及XRD图谱分析发现,淋溶后尾矿颗粒结构疏松,表面腐蚀明显,生成了CaSO_4、钙磷石等不溶物,使Zn、As后期释放减慢。

Lead-zinc mine tailings from Qinghai Province,China,were used to examine the effect of At. f inoculation on the release of Zn and As from the tailings. A static leaching simulation test was employed,using acid pretreatment to accelerate the process. With variation in the inoculation amount of At. f in leaching systems,the pH decreased,while the electrical conductivity（ EC） increased,and the oxidation-reduction potential（ ORP） decreased. At. f clearly promoted the release of Zn and As,but similar effects were not observed for the migration and release of heavy metals with different inoculation amounts. In the presence of At. f,Zn was released in greater amounts than As,and dissolution of Zn was preferred over As. Indeed,the release processes of Zn and As could be described using the Evolich and Guass models,respectively. Analysis was by scanning electron microscopy（ SEM）,energy dispersive spectroscopy（ EDS）,and X-ray diffraction（ XRD）. The residues were composed of a porous structure of tailing particles,along with a corroded surface following bioleaching. Furthermore,the formation of CaSO_4,Brushite,and other insoluble minerals slowed the release of Zn and As over time.