Brine to Lithium Carbonate: Evaporation, Polishing and Carbonation

Brine processing is a concentration business: you remove water and unwanted ions until lithium chloride or sulphate is strong enough to precipitate carbonate. Compared with hard-rock routes there is no grinding or leaching, but impurity control is harder because everything in the brine concentrates with the lithium.

Route

Step	Purpose	Equipment	Key parameter
1. Pre-treatment	Remove Mg, Ca, sulphate	Lime/soda softening, IX	Mg < 10 mg/L before concentration
2. Concentration	Raise Li to 15–25 g/L	Solar ponds or MVR/MEE	Recovery > 85%, control NaCl/KCl
3. Boron / residual Ca-Mg	Polishing	Selective IX	B < 5 mg/L
4. Carbonation	Precipitate Li₂CO₃	Reactor with Na₂CO₃ dosing, 80–90 °C	Stoichiometric control, seeding
5. Dewatering and drying	Product	Centrifuge, dryer	< 0.2% moisture

Magnesium is the project killer

Brine with a high Mg/Li ratio consumes large amounts of lime and generates a lot of gypsum sludge. Projects that look attractive on lithium grade fail on reagent cost. Run the softening test on actual brine before committing to a route.

MVR or solar?

Solar ponds are cheap to operate and slow; MVR is capital-intensive and fast, and it needs stable power. For a pilot or a small plant, MVR with a crystallizer gives control and a predictable schedule. For large tonnage in the right climate, ponds still win on opex.

Why pilot data matters here

Brine composition varies between aquifers and between seasons. A pilot that runs the actual brine for several weeks gives you the real magnesium and sulphate behaviour, the evaporator fouling rate, and a carbonate product sample for qualification.

Send the complete brine analysis (Li, Na, K, Mg, Ca, SO₄, B, Cl) and target product grade, and we will size the evaporator and polishing train.