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How does solvent extraction purify copper-bearing leach solutions?
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copper processing
Molten copper being made into plates.
In hydrometallurgy, solvent extraction is a critical process used to purify and concentrate copper from dilute leach solutions.12
The process functions through the following steps:
- Extraction: A large volume of dilute copper-bearing leach solution is mixed with a smaller volume of a water-immiscible organic solvent, typically diluted in kerosene. The copper ions selectively transfer from the aqueous leach solution into the organic solvent phase.2
- Phase Separation: The two liquids, which do not mix, are separated, effectively isolating the copper from impurities like iron that remain in the original leach solution.12
- Stripping: The copper-loaded organic solvent is then contacted with a stripping solution that has an even higher affinity for the metal. The copper is transferred from the organic solvent into this new, smaller volume of fluid.2
This process transforms a low-grade, dilute solution into a highly concentrated one—often increasing copper content from approximately 2.5 grams per litre to 50 grams per litre—making it suitable for electrowinning or other high-purity recovery methods.12