RECOVERY OF CADMIUM AND CYANIDE USING A COMBINATION OF ION-EXCHANGE AND MEMBRANE EXTRACTION

A combination of ion exchange and membrane extraction successfully rec overed cadmium and cyanide from simulated cadmium-cyanide rinsewaters. The ion exchange loading was most effective at cyanide-to-cadmium mol ar ratios of 4:1 or less; when the molar ratio exceeded 4:1, cadmium-c yanide complexes caused a chromatographic displacement of free cyanide from the resin. Cyanide-to-cadmium molar ratios in excess of 4:1 coul d be reduced to 4:1 or less by pumping the solution through a sand fil ter loaded with cadmium oxide. Regeneration of the anionic resin with sulfuric acid restored the full resin capacity and recovered the cadmi um and cyanide in separate solutions.