Influence of organic acids on pentlandite bioleaching by Acidithiobacillus ferrooxidans LR

Area of Science:

• * Biotechnology and Geomicrobiology
• * Hydrometallurgy and Bio-hydrometallurgy

Background:

• * Bioleaching utilizes chemolithoautotrophic microorganisms for metal solubilization from low-grade ores.
• * Organic acids can enhance bioleaching by providing protons and chelating metals.
• * Pentlandite ores are a significant source of nickel and cobalt.

Purpose of the Study:

• * To investigate the synergistic effects of various organic acids with Acidithiobacillus ferrooxidans in pentlandite bioleaching.
• * To evaluate the impact of organic acids on nickel (Ni) and cobalt (Co) extraction efficiency.
• * To identify optimal conditions for enhanced metal recovery from sulfide ores.

Main Methods:

• * Bioleaching experiments were conducted using pentlandite ore and Acidithiobacillus ferrooxidans.
• * Five organic acids (acetic, ascorbic, citric, lactic, oxalic) were tested individually and in combination.
• * A simplex-centroid experimental design was employed to analyze interactions between organic acids.

Main Results:

• * Oxalic acid addition improved Ni extraction by 45.6% after 15 days.
• * Co extraction yields were generally low, with citric acid showing 2.8% extraction.
• * Citric acid demonstrated a statistically significant synergistic effect on pentlandite bioleaching in the presence of A. ferrooxidans.

Conclusions:

• * A novel synergistic bioleaching system involving organic acids and A. ferrooxidans was developed.
• * Citric acid shows promise for enhancing Ni and Co extraction from pentlandite ores.
• * Further research can optimize this system for industrial application in metal recovery.