Effect of Contact with Organic Extractant LIX 84IC during Solvent Extraction Process on the Re-Establishment of Growth of Bioleaching Microorganisms

Solvent extraction (SX) used for the recovery of copper is a primary low-cost hydrometallurgical process applied extensively in cases like commercial bioleaching operations. Bioleaching solutions during SX treatment are exposed to important concentrations of organic extractants, a step that has a detrimental impact on microbial activity. The following work studies and determines the effect of this exposure on the re-establishment of growth and activity of different bioleaching microorganisms after contact and phase separation. Different bioleaching iron and sulfur -oxidizing microorganisms were tested. After contact with an industrially utilized organic extractant (LIX 84IC as extractant and Oxform SX12 as solvent), cultures were grown and their substrate utilization monitored. Acidithiobacillus ferrooxidans showed only a slight increase in doubling time without significant latency period. On the contrary, for both Sulfobacillus species studied, S. thermosulfidooxidans and S. thermotolerans, were strongly impacted showing important lag phases before growth could take place. Additionally, the SX reagent showed disruption of cell walls and protein liberation during contact with all the different strains studied.