Pregnant leach solution

Example

See it in the plant

1. Charge: 13.18 t of black mass goes into the tank with 17.95 t of sulfuric acid and 1759 kg of hydrogen peroxide, 1.2× the stoichiometric floor.
2. Dissolve: stirred and heated, the metals go into solution (2 LiMO₂ + 3 H₂SO₄ + H₂O₂ → Li₂SO₄ + 2 MSO₄ + 4 H₂O + O₂). 98% of the nickel, 98% of the cobalt, 98% of the manganese, 99% of the lithium dissolves.
3. Filter: what does not dissolve stays on the cloth: 6037 kg of residue, mostly graphite and carbon. The liquid, 6331 kg of leach solution, goes on to purification.
4. Vent: 810 kg of gas leaves the tank, oxygen from the peroxide and vapour, to the scrubber.

Use in Lemonergy

Distinguish recovered material from a qualified product.

This is a reference concept. No executable Lemonergy block has been verified for this term.

Connected concepts

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Filter press

A stack of plates covered with filter cloth and clamped together hydraulically, into which a slurry is pumped: the liquid passes the cloth and the solids stay behind as a cake. Recycling plants use it after leaching, purification and precipitation.

Impurity removal

Removing copper, iron and aluminium from the leach liquor before the valuable metals are separated, typically by cementation and by raising the pH until their hydroxides precipitate. Battery-grade products need impurities in the parts per million.

Leaching

Dissolving the metals in black mass, usually in sulfuric acid with hydrogen peroxide as a reducing agent so cobalt and manganese go into solution as their more soluble lower oxidation state. The leach liquor carries lithium, nickel, cobalt and manganese, plus impurities such as copper and aluminium.

Lixiviant

The liquid used to dissolve metals in leaching. In battery recycling it is usually sulfuric acid, sometimes hydrochloric or an organic acid, and water for some lithium iron phosphate routes.

Solvent extraction

Separating metals in the leach liquor by contacting it with an organic phase carrying an extractant that picks up one metal at a time, controlled by pH: manganese, then cobalt, then nickel, leaving lithium in the water. It is how recyclers reach battery-grade sulfates.

References & further reading

Further reading on this topic

These sources provide broader context; they are not presented as citations for every statement in this entry.

1. Lithium-Ion Battery Recycling

   U.S. Environmental Protection Agency

   Topic background · Battery construction, recycling routes and U.S. waste-management context.

2. Recycling lithium-ion batteries from electric vehicles

   Gavin Harper et al. · Nature · 2019

   Topic background · Reuse, disassembly and mechanical, hydro-, pyro- and direct recycling routes.