Selective Recovery of Gold From Acidic Solutions Using Resins With Methylenediphosphonate and Carboxymethylphosphonate Ligands

Abstract

The polymeric resins with methylenediphosphonate and carboxymethylphosphonate ligands in the ethyl ester form have been synthesized, characterized and used in the removal of Au(III) from hydrochloric acid solutions. It has been found that they are able to adsorb as much as 130±166 mg Auag of the resin at high concentration of the external solutions. At low concentrations af®nity of resins towards gold is very good and the obtained distribution coef®cient logarithm is in the range of 4.0±4.4 for the 1610 À 4 M Au(III) in 0.25±6.0 M hydrochloric acid solutions. Other metals chlorocomplexes such 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 use of the synthesized resins in the selective removal of Au(III) from the concentrated copper solution typically obtained in the SOLVENT processing of the electronic scrap. It has been possible to treat more than 1900 bed volumes of such solution (1610 À 4 M Au(III) and 1610 À 2 M Cu(II) in 3 M HCl) obtaining 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.

Recovery of gold from mining solutions using Au(III)-imprinted polymeric resins with pyridine, ethylenediamine and aminothiophosphate functionalities

“…This stage was completed within about 5 min for IIP 4-VP-EGDMA and 40 min for the other two imprinted polymers. The observed faster uptake of Au(III) onto the IIP 4-VP-EGDMA compared to the other two IIPs could be due to its larger surface area and porous structure making the functional groups easily accessible to Au (III) (Trochimczuk 2001), which is in agreement with findings regarding the surface area and pore size discussed earlier (see Table S1). After attaining equilibrium (after 5 and 40 min) in the second step, there was no further increase in the Au(III) uptake owing to the occupation of all adsorption sites by the adsorbate ion.…”

“…The high adsorption selectivity of the IIPs to gold ion compared to base metal ions at this pH can be attributed to several factors. The first factor could be the geometry of the complex anions in which gold (III) forms a square planar complex with the chloride anions (Trochimczuk 2001). The other base metal ions form tetrahedral or octahedral complexes resulting in different interactions with the IIPs.…”

Recent developments in the determination of gold by atomic spectrometry techniques

“…Carbon adsorbents were particularly very useful for recovery of gold from thiourea [30] and thiocyanate [31] solutions obtained in the leaching processes. Resins bearing amnioguanidyl ligands have revealed significant gold sorption from both acidic and alkali solution: 68 and 23 mg/g, respectively [35]. The investigated resins could be used in many cycles of sorption -desorption of AuCl 4 À where acidic thiourea solution at an ambient temperature was applied for gold recovery.…”

Effect of pre-treatment by organic solvent on leaching of copper from waste printed circuit boards (WPCBs)

“…[12]. It has been reported that hydrometallurgical processes are predictable, -easily controllable, environmentally friendly, higher selectivity to metals in comparison with pyrometallurgical methods [13].…”