Discussion on the Engineering Design of Producing Battery-Grade Lithium Carbonate from Spodumene

Discussion on the Engineering Design of Producing Battery-Grade Lithium Carbonate from Spodumene

I. Process Principles and Flow

1. Conversion Roasting
   Spodumene concentrate (α-type) is roasted in a rotary kiln to convert it into β-type lithium concentrate, which is more reactive with sulfuric acid.
2. Sulfuric Acid Leaching
   The converted lithium concentrate reacts with concentrated sulfuric acid to produce a lithium sulfate solution. The process requires precise control of temperature and acid dosage to ensure efficient lithium leaching.
3. Impurity Removal
• Calcium carbonate slurry is added to the lithium sulfate solution to precipitate calcium and magnesium impurities through a precipitation reaction.
• Further purification is achieved by adding sodium hydroxide to remove magnesium impurities through a causticization reaction.
4. Lithium Carbonate Precipitation
• Sodium carbonate is added to the purified solution to precipitate lithium carbonate.
• The precipitated lithium carbonate is then separated through thickening and centrifugation to remove residual impurities.
5. Carbonation and Thermal Decomposition
• Crude lithium carbonate is reacted with pure water and carbon dioxide to form lithium bicarbonate solution.
• The lithium bicarbonate is then thermally decomposed to produce battery-grade lithium carbonate.

II. Key Points in Engineering Design

1. Equipment Selection
• Roasting Equipment: Efficient rotary kilns should be chosen to ensure high conversion rates of spodumene.
• Leaching Equipment: Corrosion-resistant reactors are required to handle the high temperatures and acidic conditions of sulfuric acid leaching.
2. Impurity Control
• During sulfuric acid leaching and lithium carbonate precipitation, impurity levels must be strictly controlled to ensure that the final product meets battery-grade purity standards.
3. Energy Optimization
• The sulfuric acid process for lithium extraction is energy-intensive. Energy consumption can be reduced by optimizing reaction conditions and recovering waste heat.
4. Environmental Measures
• Waste slag and wastewater generated during the process must be treated to minimize environmental impact.

III. Process Optimization and Research Directions

1. Improving Lithium Recovery Rate
• Optimize roasting temperature and sulfuric acid dosage to enhance lithium leaching efficiency.
• Investigate new leaching agents or additives to improve selective lithium extraction.
2. Reducing Production Costs
• Explore alternative process routes, such as chlorination roasting, to reduce energy consumption and production time.
• Recycle by-products generated during the production process, such as sodium sulfate, to improve economic efficiency.
3. Environmentally Friendly Processes
• Develop green leaching processes to reduce the use of acids and alkalis and minimize environmental impact.

IV. Conclusion