Solvent extraction separation and recovery of copper,nickel and zinc from printed circuit board by Cyanex 272

Abstract

Studies were conducted on the simultaneous and individual extraction of metals (copper, nickel and zinc) from their sulphate solutions using [bis(2, 4, 4-trimethylpentyl) phosphinic acid] (Cyanex 272, HA) as an extractant. Effect of various parameters such as equilibrium pH, extractant concentration, sulphate and acetate ion concentration were investigated. The slope analysis method was used to determine the nature of extracted metal complexes. For the extraction of copper, [Cu(Ac)(HA₂).2HA] species was formed at all acetate and lower sulphate ion concentrations region whereas at higher sulphate and medium acetate ion concentration region, [Cu(HA)₂.HA₂] species was formed. [Zn(HA)₂.HA₂] and [Ni(Ac).(HA₂).2HA] species were formed for the extaction of zinc and nickel. Stripping behaviour of the loaded organic phase at different acidities was also investigated. Separation factor on Zn–Cu, Cu–Ni and Zn–Ni at various nickels from the leach liquor of printed circuit board was conducted and a complete process flow sheet was provided where the recovery was 96·70%Zn, 99·24%Cu and 97·16%Ni.