Investigating the impact of inoculation on bioleaching of copper flotation concentrate using a continuous reactor at pilot scale - study case: Tizert deposit

Abstract

The world is witnessing a major challenge of energy transition which involves the decline of fossil fuels specifically, but which increasingly calls on metallic resources, base metals, mainly copper. The main methods of processing copper minerals are pyrometallurgical and hydrometallurgical processes. Biohydrometallurgy appeared as a very interesting and promising alternative way. In this context, the bioleaching process was studied for the treatment and upgrading of the Tizert concentrate from the Tizert deposit, located 160 km southeast of Agadir, Morocco. Chemical, mineralogical and metagenomic characterizations were carried out on samples from the Tizert deposit. Metagenomic analysis of deposit samples revealed the abundance of genera Paenibacillus (11.38 %), followed by Phynylobacterium (7.54 %) when DSM 670 medium was used while Acidithiobacillus (41.48 %) and Pseudomonas (35.01 %) were abundant when DSM 71 medium was used, indicating the need to use selected consortium species for copper bioleaching experiments. Inoculation with the three species Acidithiobacillus ferrooxidans DSM 583, Leptospirillum ferriphilum DSM 14647 and Acidithiobacillus thiooxidans DSM 14887 was carried out. Laboratory scale leaching experiments with and without inoculation with the bacterial consortium were carried out on the copper concentrate obtained by flotation pretreatment, to compare the copper leaching behavior and yield. Inoculation with exogenous bioleaching bacteria improved the copper yield to 91 % compared to the leaching process without inoculation. These results were confirmed by a pilot-scale study with a copper yield of 95 %.