How lithium carbonate is made

Brine can sit in open ponds for months or years until the sun has taken most of its water.

stations: 8
things upstream: 19
raw sources: 12
steps from the ground: 5

The short version

Lithium carbonate comes from two places. Salar brine is pumped into sun-baked ponds for months or years, cleaned of contaminants and dosed with sodium carbonate. Spodumene rock is mined, crushed, roasted until reactive and treated with sulfuric acid, giving a lithium sulfate solution that meets the same sodium carbonate. Either way, the solid product is filtered, washed and dried.

Pump up salar brine

Salty groundwater enriched with dissolved lithium sits under high-altitude salt flats in places such as Chile and Argentina. It is pumped to the surface and spread across evaporation ponds.

Goes in
Lithium brine
Evaporate through the ponds

The sun takes most of the water over months or years. Each move to a new pond leaves a stronger solution, and potassium may be pulled from the younger ponds while the lithium builds.
Clean the concentrate

At the recovery plant, filters or ion exchange remove unwanted material. Reagents then drop other salts out of solution, and a second filtering takes those solids away. The details vary with each brine field.
Mine and crush the ore

On the hard-rock route, crews blast and dig spodumene from granitic pegmatites. It is graded and crushed so the plant gets a steady feed, and concentrates for this use hold 75 to 87% spodumene.

Goes in
Spodumene
Roast the concentrate

Spodumene in its natural alpha form barely reacts. Strong heat converts it to the more open beta form, which can trade its lithium for hydrogen in the next step.

about 1,070 °C
React with sulfuric acid

Cooled and mixed with concentrated acid, the roasted mineral gives up its lithium as lithium sulfate. Calcium hydroxide neutralizes the mix, and the waste solids are dewatered and washed. Further neutralizing steps take out iron, aluminum and magnesium.

Goes in
Sulfuric acid
Precipitate with soda ash

Sodium carbonate goes into the purified solution from either route. The product dissolves poorly compared with other lithium salts, so it falls out as a solid. One outline of the spodumene route puts the conversion at 98%.

Goes in
Soda ash
Wash and dry the powder

A rotary vacuum filter washes the crystals, and the solids are dried for sale. Some is later slurried with calcium hydroxide to make lithium hydroxide for battery makers.

Goes in
Water

End of the lineLithium carbonate Next it goes into lithium-ion cell.

Worth repeating

Seawater contains an estimated 230 billion tonnes of lithium, yet only 0.14 to 0.25 parts in every million of it are lithium.
Lithium carbonate colors fireworks red.
A mild carbon dioxide pressure makes it appear ten times more soluble in water.