Extractant
also known as reagent · extraction reagent
The extractant is the functional molecule in the organic phase, typically a few to about thirty volume percent of the organic, dissolved in a diluent. Acidic extractants such as organophosphorus acids and oximes exchange a proton for a metal cation; amine extractants form ion pairs with anionic metal complexes. Each family has its own pH window and selectivity pattern.
Why it matters in practice
Extractant choice fixes the circuit's pH operating point, its stripping chemistry and its selectivity, and therefore the whole flowsheet around it. Because the extractant is also a significant recurring cost, its loading capacity directly determines the organic flow rate and hence the size of every contactor in the circuit.
Where this appears on this site
Equipment referenced in this entry
Related terms
Reference entry GL-EXTRACTANT. Definitions on this page describe engineering practice in hydrometallurgical process design; they are not a substitute for test work on your own material.