Reactive Extraction

Abstract

Liquid-liquid extraction, leaching (solid extraction), absorption (gas extraction) and extractive distillation have in common the use of a solvent which achieves the separation. According to this, solvent recovery in a continuous solvent circuit is necessary. Usually liquid-liquid extraction operates at ambient or slightly higher temperatures and reextraction may be accomplished by a back wash or thermal strip. The transfer of a dissolved compound (solute) from one phase to another may be enhanced when admixing “salting out” agents or more selectively achieved by using “reacting” compounds dissolved in the solvent phase. The use of liquid ion exchangers, diluted in a solvent, has given rise to new approaches in the field of hydrometallurgy, in the chemical and bio-chemical industry and in environmental applications. An excellent survey of progress in these fields is given in the proceedings of the International Solvent Extraction Conferences [ISEC ′71 –′99].