Raffinate
also known as barren solution · extraction residue
The raffinate is the aqueous phase that leaves an extraction circuit after the extractant has removed the target metal. It still contains the metals that were not extracted, any residual extractant or diluent carried over as entrainment, and the original matrix salts. It is either recycled upstream, treated to recover by-products, or routed to effluent treatment.
Why it matters in practice
Raffinate is where unplanned losses show up. Organic entrainment in raffinate is a direct reagent cost and an environmental load, and a rising metal concentration in raffinate is the first sign that extraction efficiency is falling.
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Related terms
Reference entry GL-RAFFINATE. Definitions on this page describe engineering practice in hydrometallurgical process design; they are not a substitute for test work on your own material.