Clay-based lithium refers to lithium contained within fine-grained clay minerals such as smectite, hectorite, and illite. Unlike hard-rock lithium ores or brine resources, lithium in clay deposits is adsorbed or structurally bound within layered clay lattices.
These deposits typically form through volcanic ash alteration, sedimentation, and hydrothermal processes over geological time. Clay-based lithium is increasingly regarded as a strategic resource due to its vast global reserves and importance in supporting future battery-grade lithium demand.
Lithium-Bearing Clay Minerals & Occurrence
Common Lithium-Bearing Clays:
• Hectorite – smectite clay with lithium incorporated into its structure
• Montmorillonite & illite – lithium substitutes within layered phyllosilicates
Occurrence:
• Formed through volcanic alteration, weathering, and sedimentation
• Major deposits in Nevada (USA), China, and other volcanic basins
Composition & Physical Characteristics
Lithium-bearing clays are lithium-rich silicates where Li⁺ ions occupy exchangeable or structural positions within layered matrices.
| Component | Typical Range |
|---|---|
| Li₂O | ~0.3 – 0.75% (varies widely) |
| SiO₂ / Al₂O₃ | Primary clay framework |
| Fe₂O₃, MgO, K₂O | Minor constituents |
Physical Traits
| Property | Description |
|---|---|
| Structure | Layered phyllosilicate (2:1 sheet structure) |
| Density | Lower than hard rock ores |
| Mechanical Behavior | Soft, plastic, clay-like |
| Particle Form | Fine-grained, swells or disperses in water |
Traditional mechanical strength properties are not applicable, as behavior is governed by particle size, plasticity, and swelling.
Strengthening & Metallurgical Behavior
Structural Features:
• Layered silicate sheets with interlayer spaces hosting lithium ions and water
Metallurgical Interaction:
• Lithium release depends on chemical accessibility rather than crushing
• Ion exchange: Li⁺ replaced by H⁺ or Fe³⁺ during leaching
• Thermal activation expands interlayers and disrupts bonds
Strengthening behavior is irrelevant; the focus is unlocking lithium from the clay lattice.
Refining & Processing Methods
Calcination + Acid Leaching:
• Roasting at ~500–600 °C to activate clay
• Sulfuric or oxalic acid leaching releases Li⁺
• Recovery can exceed ~90%
Ion-Exchange Leaching:
• Ferric or other salts replace lithium ions
• Reduced acid consumption
Mechanical Activation + Leaching:
• Intensive milling creates defects and exposes lithium sites
• Demonstrated recoveries ~90%+
Emerging Methods:
• Electrodialysis and electrochemical separation
• Lower reagent use and environmental footprint
Industrial Lithium Products from Clays
| Product | Use |
|---|---|
| Lithium chloride (LiCl) | Intermediate chemical |
| Lithium carbonate (Li₂CO₃) | Battery-grade material |
| Lithium hydroxide (LiOH) | EV battery cathodes |
| Technical-grade salts | Ceramics, greases, specialty uses |
Applications
| Category | Uses |
|---|---|
| Energy Storage | EV batteries, grid storage, electronics |
| Industrial | Ceramics, glass, lubricants |
| Specialty | Pharmaceuticals, air treatment |
Advantages of Clay-Based Lithium
✔ Extremely large global resource base
✔ Diversifies lithium supply beyond brines and hard rock
✔ Multiple extraction technology options
✔ Potential for lower environmental impact using advanced methods
✔ Feeds directly into standard lithium chemical supply chains
Challenges & Considerations
⚠ Lower lithium grades than brines or spodumene
⚠ Complex layered chemistry requires activation
⚠ Traditional acid leaching must be carefully managed
⚠ Economics depend on extraction efficiency and scale
Why Choose Clay-Based Lithium
Clay-based lithium is strategically important for the future of the global energy transition. As demand for electric vehicles and energy storage accelerates, clay deposits provide a scalable, geographically diverse lithium source. Continued technological innovation is rapidly improving extraction efficiency and sustainability, positioning clay-based lithium as a critical contributor to long-term supply security.