Sorption of gold and silver on carbon adsorbents from thiocyanate solutions

Sorption recovery of thiocyanate gold and silver complexes on different carbon adsorbents has been studied using model solutions with concentrations 0.08-0.82 mmol/l and 0.16-1.06 mmol/l for gold and silver, respectively. The potassium thiocyanate concentration in these solutions was 0.25 mol/l and the pH of the contacting solution was ∼2. The degree of recovery exceeded 90% for gold and 80% for silver. The separate step-by-step desorption of thiocyanate gold and silver complexes was carried out by varying the initial concentration of thiocarbamide (desorption agent). The degree of recovery of noble metals can be increased up to 95% using basic thiocarbamide solutions (in 0.1-0.2 M NaOH) at the higher temperature of the process (up to 150 °C).