Oligoamine-functionalised poly(glycidyl methacrylate-ethyleneglycol dimethacrylate) resins as moderate base extractants for gold from cyanide solutions

A series of oligoamines have been attached to poly(glycidyl methacrylate) resins to yield a corresponding group of moderate base resins. Species carrying ethylenediamine, diethylenetriamine, triethylenetetramine, N,N'-bis(3-amino-propyl)ethylenediamine, and 3,3'-aminobispropylamine and phenyl-2-imidazoline are described. These have been examined as extractants for gold from alkaline cyanide solutions, along with a commercially available polystyrene-based resin carrying a 2,5,7-triazabicyclo [4,4,0]dec-5-ene functionality. Feed solutions containing only gold cyanide and also gold in the presence of the base metals Cu, Co and Ni, have been examined. The stripping of metal loaded resins using various concentrations of NaOH has also been investigated. The results of loading and stripping experiments an discussed in the light of the basicity of the various oligoamines, and also in the context of relevant data already available in the literature. Overall, though very effective gold extraction has been demonstrated with high selectivity relative to base metals, efficient stripping is problematical and has been demonstrated in only a few cases. This suggests that gold extraction and stripping does not involve only protonation/deprotonation of the moderate base functions, but extraction probably involves a contribution from gold reduction as well. (C) 2000 Elsevier Science B.V. All rights reserved.