How Eramet Extracts Lithium: The Full Process Guide

When you hear the word “lithium,” you probably think of batteries and electric cars. Yet, behind every sleek smartphone or zero‑emission vehicle lies a complex chain of mining, chemistry, and engineering. Eramet, a French mining group, has built a reputation for tackling that chain with a distinctive extraction method. Below, we walk through each stage of Eramet’s lithium‑extraction process, highlighting where the chemistry gets interesting and where the industry’s sustainability challenges appear.

From Rock to Resource: The Starting Material

Eramet’s primary feedstock is spodumene—a lithium‑rich mineral found mainly in Australia’s Greenbushes deposit and in several African projects. Spodumene comes to the plant as pale‑gray ore fragments, often mixed with quartz, feldspar, and trace metals. The first task is to crush and grind these rocks into a fine powder, a step that maximizes surface area for the chemistry that follows.

• Crushing: Heavy‑duty jaw crushers reduce ore to roughly 2‑3 cm pieces.
• Grinding: Ball mills then pulverize the material to particles under 200 µm.
• Classification: Cyclones separate fine particles from oversize chunks, sending the former to the next stage.

Thermal Conversion – Turning Spodumene “Red”

Raw spodumene is not readily soluble in acid. Eramet solves this by heating the powdered ore to about 1 050 °C in a rotary kiln. This high‑temperature treatment converts the mineral from its α‑phase (hard, low‑solubility) to the β‑phase, which looks reddish and dissolves much more easily.

Why the heat matters:

• It breaks down the crystal lattice, exposing lithium ions.
• It drives off moisture and some volatile impurities, simplifying later purification.
• It creates a more predictable material for the acid leach, improving yield consistency.

Acid Leaching – Pulling Lithium Into Solution

After cooling, the “red” spodumene is mixed with a concentrated sulfuric acid solution. The reaction—often run in stainless‑steel autoclaves at 150‑180 °C—produces lithium sulfate, along with silica, alumina, and a host of other dissolved salts.

Key parameters that Eramet monitors closely:

• Acid concentration: Typically 30‑35 % H₂SO₄, balancing reaction speed and equipment corrosion.
• Solid‑to‑liquid ratio: Around 1:3 by weight, ensuring enough acid contacts each particle.
• Reaction time: 2‑4 hours, enough for lithium to migrate into the liquid phase without over‑reacting other minerals.

Managing By‑Products

The leach liquor also contains calcium, magnesium, and iron salts. Eramet employs selective precipitation—adding lime or sodium carbonate—to immobilize these contaminants, leaving lithium sulfate in solution. This step not only improves purity but also generates solid waste that can be further processed or stabilized for disposal.

Purification and Crystallization

Once the unwanted ions are removed, the lithium‑rich solution undergoes a series of purification stages:

• Ion exchange: Specialized resins capture trace heavy metals.
• Solvent extraction: Organic solvents preferentially bind residual aluminum.
• Temperature control: Cooling the solution to 20‑25 °C encourages lithium sulfate to crystallize.

Crystals are then filtered, washed, and dried, yielding a high‑purity lithium sulfate product ready for the next conversion.

Conversion to Battery‑Grade Lithium Compounds

Battery manufacturers typically need lithium carbonate (Li₂CO₃) or lithium hydroxide (LiOH). Eramet performs a straightforward chemical conversion:

• Lithium sulfate + sodium carbonate → lithium carbonate + sodium sulfate
• Lithium carbonate + calcium hydroxide → lithium hydroxide + calcium carbonate

Both reactions occur in stirred reactors at moderate temperatures (80‑120 °C). The resulting solids are filtered, washed, and milled to particle sizes that match battery specifications.

Environmental Safeguards and Circularity

Eramet’s process, while efficient, is not without environmental footprints. The company mitigates impact in several ways:

• Energy recovery: Waste heat from the kiln feeds back into the leaching stage, cutting fuel consumption.
• Acid recycling: Spent sulfuric acid is regenerated via thermal decomposition, reducing fresh acid demand.
• Tailings management: Solid residues are compacted and stored in lined ponds, with ongoing monitoring for leachate.

In addition, research pilots are exploring direct lithium extraction from brines—a complementary route that could lower water use in arid mining regions.

Where the Industry Is Headed

The demand for lithium is set to outpace supply for the foreseeable future. Eramet’s sulfuric‑acid leach route offers a proven, scalable solution, especially for hard‑rock deposits. However, the sector is watching emerging technologies—such as electro‑chemical leaching and bio‑leaching—that promise lower carbon intensity.

For now, Eramet’s method remains a cornerstone of the global supply chain, delivering the lithium that powers everything from smartphones to solar‑storage farms. Understanding each step demystifies the journey from a simple rock to the sleek devices we rely on daily.