Unlocking the potential of sustainable bioleaching: evaluating microbially induced metal recovery in copper-bearing black shales

• Pseudomonas fluorescens supports elevated copper and molybdenum recovery. • Siderophores seem to present more effective copper leaching than low pH generation. • Potentially high copper mobilization for low-grade shale sample. • Pseudomonas fluorescens conducts bioleaching despite lack of carbon supplementation. • Diverse impact on shale particles’ surface depending on applied conditions. Some of deposits parameters, such as lower grade or peculiar composition (i.e. refractory phases, organic compounds) hinder their effective processing for metal recovery. However, bioleaching-based methods could support metal extraction from materials showing either poor metal content or complex mineralogy. In this study, two distinctly different samples of Kupferschiefer shale (LG – with low copper content, HG – organic-rich with high copper content) were examined in terms of metal bioleaching using two bacteria: Acidithiobacillus thiooxidans and Pseudomonas fluorescens . For LG sample, activity of P. fluorescens supports high extraction of Cu and Mo, while A. thiooxidans supports As extraction. For HG sample, activity of A. thiooxidans and P. fluorescens resulted in poor copper recovery of 1.8% and 7.26%, respectively. Alteration on shale surfaces were specific to the applied microorganism, revealing different features of post-leaching sulfides.