Metallic ions catalysis for improving bioleaching yield of Zn and Mn from spent Zn-Mn batteries at high pulp density of 10%

Bioleaching of spent batteries was often conducted at pulp density of 1.0% or lower. In this work, metallic ions catalytic bioleaching was used for release Zn and Mn from spent ZMBs at 10% of pulp density. The results showed only Cu²⁺ improved mobilization of Zn and Mn from the spent batteries among tested four metallic ions. When Cu²⁺ content increased from 0 to 0.8g/L, the maximum release efficiency elevated from 47.7% to 62.5% for Zn and from 30.9% to 62.4% for Mn, respectively. The Cu²⁺ catalysis boosted bioleaching of resistant hetaerolite through forming a possible intermediate CuMn₂O₄ which was subject to be attacked by Fe³⁺ based on a cycle of Fe³⁺/Fe²⁺. However, poor growth of cells, formation of KFe₃(SO₄)₂(OH)₆ and its possible blockage between cells and energy matters destroyed the cycle of Fe³⁺/Fe²⁺, stopping bioleaching of hetaerolite. The chemical reaction controlled model fitted best for describing Cu²⁺ catalytic bioleaching of spent ZMBs.