Lithium Ore Processing Equipment: From Spodumene to Lithium Carbonate Production

Introduction to Lithium Ore Processing

The global transition to clean energy and electric mobility has created unprecedented demand for lithium, a critical component in lithium-ion batteries. Spodumene, a pyroxene mineral containing lithium aluminum inosilicate, represents one of the most important commercial sources of lithium. The transformation of raw spodumene concentrate into battery-grade lithium carbonate involves multiple sophisticated processing stages, each requiring specialized equipment designed for efficiency, precision, and reliability.

This comprehensive technical article explores the complete equipment chain for lithium processing, from initial ore preparation through to final lithium carbonate production, with particular focus on the critical comminution and classification stages where particle size control directly impacts downstream chemical processing efficiency.

Stage 1: Ore Preparation and Primary Crushing

Raw spodumene ore typically arrives at processing facilities with varying moisture content and particle sizes up to several hundred millimeters. The initial preparation stage involves primary crushing to reduce ore to manageable sizes for subsequent processing. Jaw crushers and gyratory crushers are commonly employed for this duty, reducing run-of-mine ore to particles typically under 200mm.

Key considerations at this stage include minimizing fines generation (which can create dust issues and processing inefficiencies) while achieving consistent particle size distribution. Modern crushers feature hydraulic adjustment systems that allow operators to optimize crushing parameters in real-time based on ore characteristics.

Stage 2: Secondary and Tertiary Crushing

Following primary crushing, secondary crushing further reduces particle size to typically below 50mm. Cone crushers are frequently utilized for this application, offering high reduction ratios and producing well-shaped particles. For operations requiring additional size reduction, tertiary crushing with vertical shaft impactors or high-pressure grinding rolls can be implemented to achieve particles as fine as 10-20mm.

The selection of crushing equipment at these stages significantly impacts downstream grinding efficiency. Properly configured crushing circuits can reduce overall energy consumption by minimizing the work index of material entering grinding mills.

Stage 3: Grinding and Classification – The Critical Size Reduction Phase

The grinding circuit represents one of the most energy-intensive and technically challenging stages in lithium processing. Spodumene’s relatively high hardness (6.5-7 on Mohs scale) and specific crystal structure necessitate specialized grinding approaches to achieve optimal liberation while minimizing overgrinding.

Coarse Grinding Applications

For initial size reduction from crushed feed (typically ≤50mm) to intermediate products in the 30-325 mesh range (600-45μm), robust and efficient grinding solutions are essential. The MTW Series Trapezium Mill represents an optimal solution for this application stage, offering several distinct advantages for lithium processing:

• High Throughput Capacity: With processing capabilities ranging from 3-45 tons per hour depending on model selection, the MTW series accommodates both pilot-scale and full production requirements
• Precise Particle Size Control
• Enhanced Wear Protection: Combination wear plates and curved air channel design significantly extend component life when processing abrasive spodumene concentrates
• Energy Efficiency: The conical gear integral transmission system achieves 98% transmission efficiency, reducing operational costs in this energy-intensive processing stage

The working principle involves main motor-driven grinding rollers revolving around the central axis while rotating themselves, generating centrifugal force. The shovel blades throw materials between the grinding ring and rollers, forming a material layer that undergoes compressive crushing. The integrated classification system precisely controls final product particle size distribution, a critical parameter for subsequent concentration stages.

Ultra-Fine Grinding Requirements

Following concentration and before the high-temperature conversion process, spodumene concentrate often requires further size reduction to increase surface area and enhance reaction kinetics. For applications demanding ultra-fine products in the 325-2500 mesh range (45-5μm), specialized equipment is necessary.

The SCM Ultrafine Mill provides an advanced technological solution specifically engineered for these demanding applications:

• Exceptional Fineness Range
• Superior Energy Efficiency: Delivering twice the capacity of jet mills with 30% lower energy consumption, significantly reducing operational costs
• High-Precision Classification: Vertical turbine classifiers ensure sharp particle size cuts without coarse particle contamination
• Enhanced Durability: Specially hardened grinding rollers and rings provide extended service life when processing hard spodumene materials
• Environmental Compliance: Pulse dust collection efficiency exceeds international standards while acoustic insulation maintains noise levels below 75dB

The operational principle involves a main motor driving multiple-layer grinding rings to rotate. Material is dispersed into the grinding track by centrifugal force, undergoes roller compression crushing, and is progressively ground through multiple layers. Final powder collection is accomplished through cyclone collectors and pulse dust removal systems, ensuring high recovery rates and minimal environmental impact.

With models ranging from the SCM800 (0.5-4.5 t/h, 75kW) to the high-capacity SCM1680 (5.0-25 t/h, 315kW), operations can select appropriate capacity matching their production requirements while maintaining consistent product quality across the fineness spectrum.

Stage 4: Concentration – Froth Flotation

Following grinding, spodumene is separated from gangue minerals through froth flotation. This process exploits differences in surface chemistry between spodumene and associated minerals like quartz, feldspar, and mica. Proper particle size distribution achieved in the grinding circuit directly impacts flotation efficiency, with optimal performance typically achieved in the 100-200μm range for coarse flotation and finer sizes for cleaner stages.

Flotation equipment includes conditioning tanks where reagents are added to modify surface properties, followed by flotation cells where air bubbles selectively attach to hydrophobic spodumene particles, carrying them to the surface for collection. Modern column flotation cells offer enhanced separation efficiency for fine particles, while mechanical flotation cells handle coarser fractions effectively.

Stage 5: Thermal Treatment – Phase Conversion

Natural α-spodumene is refractory and relatively inert to chemical attack, necessitating thermal treatment to convert it to the more reactive β-spodumene phase. This conversion occurs at temperatures between 1000-1100°C in rotary kilns or fluidized bed reactors. Equipment selection depends on production scale, with rotary kilns dominating large-scale operations due to their robustness and ability to handle varying feed conditions.

Key design considerations include heat recovery systems to improve thermal efficiency, precise temperature control to ensure complete phase conversion without sintering, and materials capable of withstanding the aggressive high-temperature environment.

Stage 6: Acid Digestion and Lithium Extraction

Following thermal activation, β-spodumene undergoes acid digestion, typically using sulfuric acid at elevated temperatures (200-250°C) to convert lithium values to soluble lithium sulfate. Reactor design must accommodate corrosive conditions at high temperatures while providing efficient mixing and heat transfer. Titanium-clad or specialized alloy reactors are commonly employed to withstand these challenging conditions.

The digestion process produces a lithium sulfate solution along with insoluble residues, primarily silica. Solid-liquid separation through filtration or thickening follows, with filter presses or vacuum belt filters typically employed for this duty.

Stage 7: Purification and Lithium Carbonate Precipitation

The lithium sulfate solution undergoes multiple purification steps to remove impurities including calcium, magnesium, iron, and other contaminants that would compromise final product quality. Purification typically involves pH adjustment, precipitation, and filtration stages, with precise control of operating parameters critical to achieving high purity.

Final lithium carbonate precipitation occurs through reaction with sodium carbonate solution, producing technical or battery-grade lithium carbonate depending on purification efficiency. Precipitation reactors must provide controlled mixing and temperature profiles to ensure consistent crystal size distribution, which impacts subsequent filtration, washing, and drying characteristics.

Stage 8: Solid-Liquid Separation and Drying

The precipitated lithium carbonate slurry undergoes dewatering through centrifugation or filtration, followed by drying to achieve the specified moisture content. Centrifugal dryers, fluidized bed dryers, or rotary dryers may be employed depending on production scale and product specifications.

Final product packaging completes the process, with bagging systems designed to prevent contamination and moisture uptake, which can compromise product quality during storage and transportation.

Equipment Selection Considerations for Lithium Processing

Selecting appropriate equipment for lithium processing requires careful consideration of multiple factors:

• Ore Characteristics: Hardness, abrasiveness, moisture content, and mineralogy influence equipment selection throughout the process flowsheet
• Production Scale: Equipment must be appropriately scaled from pilot operations (1-10 tph) to full-scale production facilities (50-500+ tph)
• Energy Efficiency: Grinding and thermal processing stages account for the majority of energy consumption, making efficiency a critical selection criterion
• Operational Flexibility: Equipment should accommodate variations in feed characteristics and production rate requirements
• Environmental Compliance: Dust control, noise emissions, and water management requirements influence equipment selection and ancillary systems
• Life Cycle Costs: Beyond initial capital investment, consideration of maintenance requirements, wear part consumption, and operational efficiency determines total cost of ownership

Future Trends in Lithium Processing Equipment

The evolving lithium industry is driving equipment development in several key areas:

• Digitalization and Automation: Advanced process control systems incorporating machine learning algorithms optimize equipment performance and product quality
• Energy Integration: Equipment designs increasingly focus on heat recovery and energy integration to reduce operating costs and environmental impact
• Modular Design: Pre-fabricated, modular equipment packages reduce installation time and capital costs while improving project execution certainty
• Water Recycling: Equipment designs that minimize freshwater consumption and maximize recycling address water scarcity concerns in many lithium-rich regions
• Direct Lithium Extraction: Emerging technologies may transform conventional processing routes, requiring specialized equipment for adsorption, ion exchange, or membrane separation

Conclusion

The transformation of spodumene ore to high-purity lithium carbonate requires a sophisticated sequence of specialized processing equipment. Each stage presents unique technical challenges, with the grinding and classification phases particularly critical to overall process efficiency and economics. The selection of appropriate grinding technology, such as the MTW Series Trapezium Mill for intermediate grinding and SCM Ultrafine Mill for fine and ultra-fine applications, directly impacts downstream processing performance, energy consumption, and final product quality.

As lithium demand continues to grow, driven by the global energy transition, equipment suppliers are responding with increasingly efficient, reliable, and environmentally responsible solutions. Proper equipment selection, integrated process design, and operational excellence will remain fundamental to establishing competitive lithium production operations capable of meeting the quality and volume requirements of the battery materials market.