Acidithiobacillus ferrooxidans对数期的不同时期添加废旧锂电池对两步生物浸出工艺性能的影响

为了提高废旧锂电池 (LIBs) 的生物浸出效率，采用了氧化亚铁硫杆菌 (Acidithiobacillus ferrooxidans，简称A. ferrooxidans) 两步浸出废旧LIBs，考察在A. ferrooxidans对数期的前、中和后期向浸出体系中添加废旧LIBs对金属浸出效率的影响。结果表明，在对数期后期加入LIBs，A. ferrooxidans实现了100% Mn、76.82% Co、84.42% Ni和100% Li的浸出，比前和中期投加LIBs提高了4.51%~17.85% Co和16.38%~20.42% Ni。机理分析表明，A. ferrooxidans在对数期后期具有较强的产酸能力，比对数期前期和中期产生更多生物酸攻击废旧LIBs，导致金属释放。而释放的Fe²⁺可为A. ferrooxidans的生长提供能源物质，同时提供电子将LIBs中难溶解的Co(Ⅲ)、Ni(Ⅲ)和Mn(Ⅳ)还原为易被生物酸浸出的Co(Ⅱ)、Ni(Ⅱ)、Mn(Ⅱ)，从而促进金属浸出。采用两步法生物浸出废旧LIBs时，为获得较高的生物浸出效率，需要在对数期的后期加入LIBs。本研究结果可为生物浸出废旧LIBs的工业化提供参考。

Effects of two-step bioleaching process on spent lithium ion batteries leaching during different stages of logarithmic growth of Acidithiobacillus ferrooxidans

To improve the bioleaching efficiency of spent lithium batteries (LIBs), this study investigated Acidithiobacillus ferrooxidans (A. ferrooxidans) two-step leaching of spent LIBs during early, middle and late stages of logarithmic growth. The results showed that A. ferrooxidans could achieve a leaching efficiency of 100% Mn, 76.82% Co, 84.42% Ni and 100% Li by adding LIBs during late logarithmic phase and improve 4.51% to 17.85% Co and 16.38% to 20.42% Ni compared with early and mid-logarithmic growth. Mechanism analysis showed that A. ferrooxidans has a high capacity for acid production during the late logarithmic phase to attack spent LIBs, leading to an increased release of metal ions, as compared to early and mid-logarithmic growth. The released of Fe2+ could provide energy for the growth of A. ferrooxidans and release electrons to reduce the insoluble Co(Ⅲ), Ni(Ⅲ) and Mn(Ⅳ) in LIBs to Co(Ⅱ), Ni(Ⅱ) and Mn(Ⅱ), which were easily bioleached by this microorganism. In conclusion, to reach high leaching efficiencies, spent LIBs should be exposed to A. ferrooxidans during its the late logarithmic phase, when leaching was carried out by a two-step bioleaching method and the results of this study may provide a reference for the industrialisation of bioleaching of spent LIBs.