微生物浸出法从石煤提钒尾渣中回收钒和铜的研究

Recovery of Vanadium and Copper from Vanadium Tailings from Stone Coal by Microbial Leaching

中国堆存的石煤提钒尾渣量高达数十亿吨,尾渣中含有钒、铜等多种金属,高效回收尾渣中有价金属既可以实现其资源化,同时防止尾渣污染周边环境。本文采用微生物浸出技术回收石煤提钒尾渣中有价金属V和Cu,重点研究了不同初始pH、溶氧量(以摇床转速表征)、黄铁矿添加量、浸出时间等不同因素对氧化亚铁硫杆菌(T.f菌)浸出尾渣中金属钒、铜的影响。结果表明,初始pH 2~4范围内对V,Cu浸出率影响不大,较高的摇床转速有利于V,Cu的浸出;在初始pH为2、摇床转速170 r·min^(-1)、黄铁矿添加量15 g·L^(-1)的条件下,T.f菌浸出尾渣10天后,V和Cu浸出率分别达到83.4%和87.8%,相比单独酸浸体系,V和Cu浸出率分别提高了32.6%和17.92%,说明T.f菌在浸出石煤提钒尾渣过程中起了关键作用。研究结果将为推动微生物技术在石煤提钒尾渣资源化的稳定应用进程提供指导。

The grade of vanadium in stone coals is generally low,so the amount of vanadium tailings piled up from stone coal in China is up to billions of tons.At present,the comprehensive utilization rate of vanadium extraction tailings is very low,and there are some valuable metals in the tailings.The microbial leaching is an effective technology to remove metals in the tailings of vanadium extraction from stone coal.On the one hand,the heavy metal content of the tailings after microbial leaching is reduced,which improves the safety of tailings stacking or comprehensive utilization.On the other hand,the leaching solution produced after leaching contains a certain concentration of heavy metal ions,which can be recycled by hydrometallurgical technical means to maximize the value of the tailings.Therefore,efficient recovery of valuable metals in the tailings can not only realize its resource recovery,but also prevent the tailings from polluting the surroundings.The vanadium extraction tailing samples used in this paper contained various metals such as vanadium and copper.And the microbial leaching technology was used to recover the valuable metals V and Cu in the tailings of vanadium extraction from stone coal.The leaching strain was Thiobacillus ferrooxidans(T.f bacteria),which was isolated from the pit waste⁃water of a copper mine in Jiangxi,China,by the laboratory.During the experiment,the cryopreserved strains were inoculated into 9K medium for activation,and when cultured to the stable phase,the T.f bacteria were used as the test strain.The static bioleaching experiment was carried out in shake flasks,and 1 g stone coal vanadium tailings and 10%(v/v)T.f bacteria were added to a 250 ml Erlenmeyer flask containing 90 ml 9K medium.The shake flasks were kept shaking at(30±2)℃.During the bioleaching experiment,different leaching conditions were controlled,and the effects of different initial pH,dissolved oxygen(characterized by rotational speed),pyrite addition,leaching time and other factors on the leaching of metal vanadium and copper in the tailings of T.f bacteria were investigated.The leachate in each Erlenmeyer flask was collected periodically to determine pH,oxidation-reduction potential,the concentration of vanadium and copper.The consumed solution was supplemented with the dilute sulfuric acid solution of pH=2.0.The experimental results showed that the initial pH range of 2~4 had little effect on the leaching rate of V and Cu.When the initial pH was higher(pH=4),the leaching system H^(+) was less,and the initial leaching efficiency of V and Cu was slow,but with the growth and reproduction of T.f bacteria,the acid production reduced the system pH and the system H^(+) concentration increased,which facilitated the tailings electrochemical corrosion reaction,and provided a certain H^(+) to destroy the tailings lattice structure,and then improved the leaching rate.The higher shaker speed was beneficial to the leaching of V and Cu,and the shaker speed within 150~170 r·min^(-1) was more suitable for the growth of T.f bacteria,with a fast growth rate and good activity.The pyrite could provide continuous and stable energy source for T.f bacteria,and contribute to the efficient leaching of valuable metal in vanadium tailings.Under the conditions of initial pH of 2,shaker speed of 170 r·min^(-1) and addition of pyrite at 15 g·L^(-1),after 10 days of T.f bacteria leaching tailings,the V and Cu leaching rates reached 83.4%and 87.8%,respectively,compared with acid in the leaching system,the leaching rates of V and Cu increased by 32.6%and 17.92%,respectively,indicating that T.f bacteria played a key role in the extraction of vanadium tailings from stone coal.The reasons might be that T.f bacteria could be adsorbed on the surface of vanadium extraction tailings,and a large number of ferrous oxidase and cytochrome oxidoreductase produced by the bacteria,which participated in the biochemical reaction inside and outside the cell body,and destroyed the crystal structure of vanadium extraction tailings to release vanadium and copper ions.The research results would provide guidance for the stable application process of microbial technology in the resource recovery of vanadium tailings from stone coal.