Abstract

The possibility of selective extraction and multiple concentration of copper in the form of ultrafine precipitate from dilute Cu2+-Zn2+ solutions by using a suitable sorbent and an effective mode of its regeneration was demonstrated. The extraction was performed in the dynamic mode in column-type reactors filled with an aminoanionite as a selective complexing sorbent, the regeneration of which was conducted by chemical reduction of Cu2+ in the ionite after its saturation. It was established that saturation-reduction cycles repeated many times result in the accumulation of metallic copper at the surface and in the bulk of the sorbent.

The mechanism of the process includes the formation of complexes of copper and zinc with amino groups of the ionite and the subsequent displacement of Zn2+ ions from the anionite due to its higher affinity to Cu2+ ions followed by the conversion of Cu2+ ions to an unsorbable form (dispersed metallic copper). It was demonstrated that the presence of dispersed copper stimulates the additional sorption of Cu2+ ions via redox conproportionation. This method makes it possible to obtain a degree of concentration of copper ions in three cycles > 300% higher than that attainable in the purely ion-exchange mode (without chemical reduction).