Enhanced copper recovery from low grade copper sulfide ores through bioleaching using residues produced by fermentation of agricultural wastes

Effects of residues produced by agricultural wastes fermentation (AWF) on low grade copper sulfide ores bioleaching, copper recovery, and microbial community were investigated. The results indicated that adding appropriate bulk of AWF made contributions to low grade copper sulfide ores bioleaching, which may be mainly realized through reducing the passivation layer formed by Fe³⁺ hydrolysis. Improved copper recovery (78.35%) and bacteria concentration (9.56 × 10⁷ cells·mL⁻¹) were yielded in the presence of 5 g·L⁻¹ AWF. The result of 16S rDNA analysis demonstrated that microbial community was differentiated by adding AWF. Bacteria proportion, such as Acidithiobacillus ferrooxidans, Moraxella osloensis, and Lactobacillus acetotolerans changed distinctly. Great difference between samples was showed according to beta diversity index, and the maximum value reached 0.375. Acidithiobacillus ferrooxidans accounted for the highest proportion throughout the bioleaching process, and that of sample in the presence of 5 g·L⁻¹ AWF reached 28.63%. The results should show reference to application of agricultural wastes and low grade copper sulfide ores.