Comparison of three different bioleaching systems for Li recovery from lepidolite

Area of Science:

• Biotechnology
• Environmental Science
• Materials Science

Background:

• Lithium extraction from lepidolite is crucial for battery production.
• Biological methods offer a sustainable alternative to traditional chemical extraction.
• Different microorganisms exhibit varying efficiencies in metal bioleaching.

Purpose of the Study:

• To evaluate the efficacy of three distinct biological systems for lithium extraction from lepidolite.
• To compare the performance of autotrophic bacteria, heterotrophic fungi, and yeast in lithium bioleaching.
• To investigate the mechanisms and yields of lithium extraction by different microbial consortia.

Main Methods:

• Bioleaching experiments using a bacterial consortium (Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans), Aspergillus niger, and Rhodotorula mucilaginosa.
• Analysis of dissolved lithium concentrations over time.
• X-ray diffraction (XRD) analysis of bioleaching residues.
• Determination of lithium bioaccumulation within microbial biomass.

Main Results:

• The bacterial consortium achieved 11 mg/L lithium dissolution over 336 days, with an 8.8% final yield.
• Fungal and yeast bioleaching were faster (40 days) but less efficient (0.2% and 1.1% yields, respectively).
• Bioaccumulation was significant for R. mucilaginosa (92%) and A. niger (77%), indicating its importance in their extraction mechanisms.

Conclusions:

• Autotrophic bacteria are effective for lithium extraction from lepidolite, albeit with longer processing times.
• Heterotrophic organisms facilitate faster but lower-yield lithium extraction, with bioaccumulation being a key factor.
• A two-step bioleaching approach combining heterotrophic and autotrophic organisms may enhance both kinetics and efficiency.