Complete bioleaching of Co and Ni from spent batteries by a novel silver ion catalyzed process

In the present work, bioleaching of two valuable metals of cobalt (Co) and nickel (Ni) from spent lithium-ion batteries (LIBs) of laptop by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans through a novel adaptation procedure was investigated. Different bioleaching methods including A. ferrooxidans and A. thiooxidans spent medium, A. ferrooxidans one-step and two-step bioleaching were carried out. The effect of silver ion on the bioleaching of Co and Ni in these methods was evaluated. Moreover, a novel strain adaptation approach to the toxic solid content of the battery powder was chosen, which resulted in a very short adaptation time and bioleaching (2 days). Even though silver ion did not have a significant effect on the spent medium method, it had an increasing effect of 26% and 7%, for Co and Ni recovery, respectively, on two-step bioleaching with silver ion-adapted A. ferrooxidans, in gradual addition of the battery powder. The highest extraction results in the spent medium method were 45.2% and 71.5% for Co and Ni, respectively, and a very high extraction yield of 99.95% for these metals was achieved in a short time of only 3 days by two-step bioleaching with gradual addition of the solid content and in the presence of Ag⁺. KEY POINTS: • Mixed spent medium of acidophilic bacteria resulted in higher Ni and Co extraction. • Adaptation to Ag⁺ has enhanced the strain capability for Co and Ni extraction. • With Ag⁺ presence, Co and Ni extraction reached 99.95% in two-step bioleaching.