Froth flotoextraction, a new method of metal separation from aqueous solutions

Abstract

A new method of extraction and separation of metals from aqueous solutions, referred to as `froth flotoextraction', is proposed. This method combines two well-known processes: solvent extraction and froth flotation. Extraction is performed by an organic acid extractant at pH values characteristic for each metal, froth is formed by the extract, air bubbles transport the extract phase to the froth and at the same time mix the solution. The method combines high productivity and low cost of flotation with selectivity and low residual metal content of solvent extraction. An equation describing phase separation efficiency is proposed and used for optimization of the process. The method is tested and used in the industrial technology of water recycling in a Russian chemical plant. The final operations of the technology are solvent extraction purification of two froth products containing zinc and copper to produce their sulphates of `chemically pure' grade and flotation decontamination of the recycling water from the residual extractant.