Selective recovery of gold from acidic solutions using resins with methylenediphosphonate and carboxymethylphosphonate ligands

The polymeric resins with methylenediphosphonate and carboxy-methylphosphon ate ligands in the ethyl ester form have been synthesized characterized and used in the removal of Au(III) from hydrochloric acid solutions. It has be en found that they are able to adsorb as much as 130-166 mg Au/g of the res in at high concentration of the external solutions. At low concentrations a ffinity of resins towards gold is very good and the obtained distribution c oefficient logarithm is in the range of 4.0-4.4 for the 1 x 10(-4) M Au(III ) in 0.25-6.0 M hydrochloric acid solutions. Other metals chlorocomplexes s uch as Fe(III), Pd(II), Pt(II) and Ag(I) are removed to a lesser extent and the resins do not recognize Cu(II) chlorocomplexes. This allows for the us e of the synthesized resins in the selective removal of Au(III) from the co ncentrated copper solution typically obtained in the processing of the elec tronic scrap. It has been possible to treat more than 1900 bed volumes of s uch solution (1 x 10(-4) M Au(III) and 1 x 10(-2) M Cu(II) in 3M HCl) obtai ning sorption of 70 mg Au(III) on resin 1 with diphosphonate ligands. This resin has been effectively regenerated using 5 wt.% solution of thiourea in 0.5 M HCl.