The extraction of lithium from spent batteries, especially lithium-ion batteries (LIBs), is a multi-step process that can involve several chemical and physical techniques to reclaim lithium and other valuable metals. Here’s an overview of the primary steps involved:
1. Battery Collection and Pre-Treatment
• Discharge: Batteries are safely discharged to avoid hazards.
• Dismantling: The batteries are dismantled to separate different components, such as the casing, electrolyte, separator, and active material.
• Crushing and Sieving: Dismantled battery parts are then crushed, and different particle sizes are separated through sieving, preparing them for further processing.
2. Leaching
• Acid Leaching: The crushed materials are treated with acids like sulfuric acid (H₂SO₄) or hydrochloric acid (HCl), often combined with hydrogen peroxide (H₂O₂) as a reducing agent. This step dissolves lithium and other metals (like cobalt, nickel, and manganese) from the electrode material.
• Alkaline Leaching: In some cases, an alkaline solution can be used, though acid leaching is more common for lithium recovery.
3. Separation and Purification
• After leaching, the solution contains lithium ions along with other metal ions. Different methods are used to selectively recover each metal:
• Solvent Extraction: Organic solvents selectively extract metals, allowing for their separation.
• Precipitation: Adjusting the pH or adding chemicals can cause specific metals to precipitate out. For example, lithium can be precipitated as lithium carbonate (Li₂CO₃) or lithium hydroxide (LiOH) using sodium carbonate or other agents.
4. Lithium Recovery
• Precipitation of Lithium Salts: Lithium is precipitated as lithium carbonate or lithium hydroxide, depending on the end-use requirements. These salts can then be further purified, dried, and collected for reuse.
5. Recycling or Disposal of Residuals
• The remaining materials, including metals that were not recovered, solvents, and residues, are either recycled, treated for environmental safety, or disposed of properly.
Advanced and Alternative Methods
Research is ongoing to improve lithium recovery methods and make them more eco-friendly. These include:
• Direct Recycling: Recovering active cathode material without complete chemical breakdown.
• Pyrometallurgical Processes: Using high temperatures to separate metals, though this requires more energy and can release harmful gases.
• Bioleaching: Utilizing microorganisms to leach lithium, an environmentally friendly but less common technique.
Applications of Recovered Lithium
Recovered lithium from spent batteries can be repurposed for new lithium-ion batteries or other industrial uses, contributing to a sustainable battery lifecycle and reducing the need for raw lithium mining.
This approach ensures efficient lithium recovery and minimizes environmental impact by reducing battery waste and dependence on raw lithium sources.
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