Lithium Carbonate Preparation from Brine

Lithium carbonate (Li₂CO₃) is a core raw material in new energy, pharmaceuticals, and chemicals, widely used in lithium battery cathode materials, pharmaceutical intermediates, glass ceramics, lubricants, and other industries. The advancement of production equipment directly determines product quality, production efficiency, and resource utilization. Tianli specializes in the production of lithium carbonate from brine, having built a complete set of standardized production equipment. We adopt mature and advanced brine lithium extraction technology, covering the entire process from brine pretreatment, purification and impurity removal, concentration and crystallization, to lithium precipitation and refining. Leveraging our comprehensive technological advantages, we provide customers with efficient, low-consumption, environmentally friendly, and intelligent solutions for the production of lithium carbonate from brine, helping them to achieve large-scale, green production and seize the initiative in the development of the new energy industry.

I. Properties of Core Materials

Lithium carbonate is a white monoclinic crystal with the molecular formula Li₂CO₃, relative molecular mass of 73.89, density of 2.11 g/cm³, melting point of 723℃, and boiling point of 1310℃. It is sparingly soluble in water and insoluble in ethanol, and its purity requirement is ≥99.5%. The production process requires strict control over the brine purification precision, reaction temperature, and concentration to ensure product quality and prevent impurities from affecting production efficiency.

II. Core Process Flow Introduction

The mainstream process for lithium extraction from salt lake brine is adsorption + membrane separation combined technology, and the basic process flow includes the following core steps.

1. Lithium extraction by adsorption

After potassium extraction, the old brine (or raw brine) enters an adsorption tower where an aluminum-based adsorbent is used for selective adsorption of lithium ions. This adsorbent is a core patented technology, capable of efficiently capturing lithium ions from brine with a high magnesium-to-lithium ratio, achieving a magnesium-to-lithium separation factor exceeding 1000. After adsorption saturation, the brine is eluted with fresh water to obtain a qualified lithium chloride-rich solution. The adsorption tailings are returned to the mining area and dissolved using solid-liquid conversion technology, achieving resource recycling.

2. Membrane separation and purification

The adsorbed solution sequentially enters the nanofiltration membrane system and the reverse osmosis membrane system for further impurity removal and concentration. The main function of the nanofiltration membrane is to remove divalent and polyvalent ions such as calcium and magnesium from the solution. The single-stage nanofiltration permeate recovery rate can reach 90%, and the magnesium rejection rate can reach 98%. The reverse osmosis membrane further removes water and concentrates the lithium ion concentration, with a permeate recovery rate of over 75%. Some units are also equipped with electrodialysis system for purification.

3. Concentration and evaporation: pure lithium-containing brine is fed into the MVR evaporation and concentration system where water is evaporated under low temperature and negative pressure conditions, concentrating the lithium ion concentration to 10-15 g/L. Waste heat is recovered during the evaporation process and used for brine preheating, achieving energy recycling and avoiding lithium salt decomposition.

4. Lithium precipitation reaction: the concentrated lithium-containing brine is sent to the lithium precipitation reaction tank, and carbonation reagent is added according to the precise ratio. The reaction temperature is controlled at 80-90℃, and the reaction is stirred to generate lithium carbonate precipitate. The reaction equation is 2Li⁺ + Na₂CO₃ → Li₂CO₃↓ + 2Na⁺. The lithium precipitation rate is ≥98%. The slurry after the reaction is sent to the solid-liquid separation equipment.

5. Refining, drying and exhaust gas treatment: the separated crude lithium carbonate is washed with water and recrystallized to remove trace impurities. It is then sent to drying equipment for removing moisture content ≤0.2% and obtain high-purity lithium carbonate finished product. The small amount of saline wastewater generated during the production process is treated and recycled, and the exhaust gas is purified and discharged after reaching the emission standard.

III. Core Technical Advantages

1. Short process and high production efficiency

Direct lithium extraction from raw brine significantly shortens the production cycle, taking only a few hours from brine input to finished product output, while traditional salt field concentration processes typically take several months. Continuous moving bed adsorption technology enables continuous adsorption and desorption operations, achieving an average lithium yield of over 90%, significantly improving production capacity per unit time.

2. High product purity, meeting the needs of high-end applications.

The combined process of adsorption-membrane separation-lithium precipitation can effectively remove impurity ions such as calcium, magnesium, boron, and chloride. Nanofiltration membranes can achieve a rejection rate of over 98% for divalent and multivalent ions, and the impurity content in the product can be controlled at an extremely low level. This enables the stable production of battery-grade lithium carbonate, meeting the stringent purity requirements of raw materials in high-end fields such as power batteries and energy storage.

3. Reduced significantly energy and resource consumption

Comparing with lithium extraction from ore, lithium extraction from salt lake brine eliminates energy-intensive processes such as high-temperature calcination. Membrane separation technology enables water recycling, significantly reducing freshwater consumption. Adsorbed tailings can be returned to the mining area for ore recycling, achieving multiple rounds of brine resource utilization and resulting in high overall resource utilization efficiency.

4. Green and environmentally friendly

The entire process requires no high-temperature or high-pressure reaction, making the production process mild and safe. The adsorbent is reusable, and there are no harmful waste gas emissions. The membrane system achieves closed-loop circulation, resulting in low wastewater discharge. The overall process conforms to the concepts of green chemistry and sustainable development, with an environmental impact far lower than traditional ore-based lithium extraction processes.

5. Strong adaptability to raw materials and high resource utilization rate

This technology is well adaptable to different types of salt lake brines (chloride-type, sulfate-type, and carbonate-type). By selecting adsorbents and membrane modules and adjusting process parameters, it can be optimized and matched for different brine chemical compositions, making it suitable for the development of low-grade and complex lithium resources, and significantly expanding the range of exploitable lithium resources.