Purification of lithium carbonate from sulphate solutions

What is Li₂CO₃

Lithium carbonate is the carbonate salt of lithium Li₂CO₃, one of the most important lithium compounds widely applied in the processing of metal oxides, lithium-ion batteries and ceramics. Lithium carbonate is also used in medicine to treat mood disorders.

In addition, the demand for Li₂CO₃ is rapidly increasing due to the new development and production of electric vehicles in the last years.

What is spodumene

Sources of lithium salt Li₂CO₃ come mainly from lithium minerals. A certain amount of lithium contains more than 100 different minerals, of which spodumene is the main one actively mined for lithium production. Spodumene has a theoretical lithium content of about 8 %.

Lithium ore deposits

Due to its high lithium content, spodumene is considered the most important lithium ore mineral. Spodumene is found in lithium ore deposits such as those found in Australia, Asia, Africa, Brazil and North America.

Lithium extraction from spodumene

The dominant lithium extraction technology from lithium minerals, especially spodumene, is a sulfuric acid process. After the lithium ore is ground and dissolved with sulphuric acid, the roasting to lithium sulphate is followed. The next step is water leaching, followed by mixing with sodium carbonate to obtain lithium carbonate. The maximum recovery of this process is about 95 %.

However, the main drawbacks of spodumene processing by sulphuric acid are generating huge quantities of waste residue and the necessity of high-temperature pretreatment.

Innovated method for lithium carbonate purification using MEGA special electrodialysis

Limited lithium reserves are increasing pressure on lithium ore processors challenging the cost and efficiency of current lithium recovery methods.

MemBrain, the subsidiary of MEGA, researchers have developed a highly selective electrodialysis system to remove impurities from lithium-rich solutions usable for lithium ore / spodumene extraction.

The advanced electrodialysis shows a high ability to selectively extract lithium carbonate of high grade from lithium sulphate with lower costs than other conventional technologies.

How does it work?

We offer higher purity and lower energy processing technology that simplifies processing block flow diagrams, boosts yield, and lowers cost.

Purification of lithium carbonate from sulphate solutions using MEGA patented electrodialysis, which works in the unique configuration of these 2 steps:

1 step – MemBrain patented electrodialysis in special configuration:

Li₂SO₄ + NaHCO₃ → Na₂SO₄ + LiHCO₃

2 step - crystallization:

2 LiHCO₃ (aq) → Li₂CO₃ (s) + CO₂ (g) + H₂O (g)

MEGA ED highlights

Lithium carbonate purity 99.99 % | 2 feeds – 2 products |
Crystallization temperature = 90 – 95 °C | Atmospheric pressure

Benefits of using MEGA special electrodialysis to purify Li₂CO₃ from lithium ore

• Li₂CO₃ purity up to 99.9 % after bicarbonate heating.
• Lithium concentration in the produced LiHCO₃ is up to 4000 mg/l.
• Special configuration ED reduces the complexity of production and waste management.
• High purity commodity Li₂CO₃ product where SO₄^2- < 0.05 % DMB.
• It is possible to separate Li₂CO₃ from Na, K, Rb salts species by precipitation following ED.
• Bicarbonate intermediate purity after ED is over 97.5 % as Li / (Li + S) by mass.
• Electrodialysis lowers the amount of water-salt solutions for handling.
• Electrodialysis is a saving cost for the evaporation steps.
• Production routes using electrodialysis can be switched from carbonate to hydroxide.