Novel Extraction Process for Gold Recovery from Thiosulfate Solution Using Phosphonium Ionic Liquids

Abstract

A novel and sustainable technology to recover gold from thiosulfate medium using ionic liquids, i.e., Cyphos IL 101 (Cy IL 101) and Cyphos IL 102 (Cy IL 102) diluted in toluene, has been developed. Gold was extracted into the ionic liquid phase as [{P66614 +}3{Au­(S2O3)2 3–}] and stripped using NaCl solution. The recyclability of ionic liquids has shown promising recirculation of the solvents for the extraction of gold from thiosulfate medium. Gold was quantitatively extracted from 0.2 mol/L sodium thiosulfate initially containing 10 mg/L gold at pH = 9.0 with 1.25 mmol/L ionic liquid (Cy IL 101 or Cy IL 102) in one stage at A/O = 2, whereas total gold stripping with 1.5 mol/L NaCl also needed one stage at A/O = 1. Using a high A/O ratio in the extraction stage (A/O = 10) and low (A/O = 1/10) in the stripping stage confirmed the economic and environmental viability of the process. The results revealed that Cy IL 101 presents slightly better behavior toward gold recovery than Cy IL 102 and is a viable and promising alternative to recover gold from the thiosulfate medium on a pilot scale. The overall study confirmed the suitability of the developed scheme for industrial application to provide economic and environmental benefits.

Ionic Liquids as Components of Systems for Metal Extraction

“…Cyphos 101 in toluene is an efficient extractant for gold(III) from thiosulfate solutions, with an extraction efficiency of 99% [31]; undiluted Cyphos 101 provides quantitative recovery of platinum(IV) and palladium(II) from a leaching acidic solution of waste catalytic converters [32].…”

Efficient Gold Recovery from Cyanide Solution Using Magnetic Activated Carbon

“…The loading capacity depends on the specific surface area and pore structure of the activated carbon; however, adsorption rate is dependent upon the particle size and specific surface area of the activated carbon, mixing efficiency, and pulp density . Gold adsorption rates in CIP and CIL operations are usually very low, and the gold loading capacity in CIP and CIL operations is far below the equibrilim capacity of the activated carbon. , In order to effectively separate the loaded activated carbon from the slurry by screening, the activated carbon used in the operations has to be coarse particles (diameter = 1.0–3.0 mm), and the adsorption rate of the activated carbon decreases significantly with the increase of the particle size because the mean pore length increases. , Thus, the adsorption rate of activated carbon used in the current mining process is mainly limited by the particle size, even though, there is still much gold left and fine carbon particles that cannot be recovered. , …”

“…13,17 Thus, the adsorption rate of activated carbon used in the current mining process is mainly limited by the particle size, even though, there is still much gold left and fine carbon particles that cannot be recovered. 18,19 There have been some developments on activated carbon for aurocyanide recovery in the past decade. Poinern et al 15 investigated the use of macadamia nut based granular activated carbon for aurocyanide adsorption, and discovered that the gold loading capacity of this activated carbon is comparable to the commercial coconut-shell-based activated carbon.…”

Microfluidic Fabrication of Micropolymer Inclusion Beads for the Recovery of Gold from Electronic Scrap

“…Kejun et al extracted Au­(I) from thiosulfate solutions with trioctylmethylammonium chloride, which is the main component of Aliquat 336, dissolved in a mixture of n -octane and 1-hexanol . Mahandra et al reported on the use of ionic liquids such as Cyphos IL 101 and Cyphos IL 102 for the sustainable recovery of Au­(I) from thiosulfate solutions . Mowafy and Mohamed extracted Au­(III) from hydrochloric acid solutions with long-chain monoamides in aromatic and aliphatic diluents.…”

“…1 Mahandra et al reported on the use of ionic liquids such as Cyphos IL 101 and Cyphos IL 102 for the sustainable recovery of Au(I) from thiosulfate solutions. 2 Mowafy and Mohamed 3 extracted Au(III) from hydrochloric acid solutions with long-chain monoamides in aromatic and aliphatic diluents. Oshima et al reported on the successful extraction of Au(III) from hydrochloric acid solutions using aromatic ethers 4 and ketone compounds, 5 while Salvadóet al 6 demonstrated the suitability of tri-isobutyl phosphine sulfide in toluene.…”