Intensification of Gold Sorption by Anion Exchange Resins

Gold extraction technology based on anion exchange resins with mixed basicity, commonly used in former soviet countries, includes a complicated and expensive process of resin regeneration and gold stripping by thiocarbamide solution. Satisfactory sorption properties of weak base anion exchange resin at pH 6–8 and low cost of metal stripping by sodium hydroxide solution have aroused considerable interest in these resins as perspective means of gold extraction from cyanide pulps on a large scale. However, the possibility of industrial use of weak base anion exchange resins is hindered by their extremely low sorption activity at pH 10.5 and the formation and release of HCN in the pulp at pH 6–8.

The development of weak-based anion exchange resins which permits efficient gold sorption at pH 10.5 has already been described in literature. A special procedure for treating cyanide pulps has been devised in ?Irgiredmet”. It allows a sigificant rise of gold distribution coefficient between anion exchange resins and liquid phase.

Studies including counter-current tests of gold sorption by anion exchange resins of mixed and weak basicity from cyanide solutions and pulps treated accordingly were carried out. It was found that the gold capacity of mixed base resins has risen by 2–3 times, and the resin flowrate and reagent consumption during its regeneration and gold stripping by thiocarbamide solution have decreased proportionally. After special treatment the gold capacity of weak base resins in solutions and pulps is 3–6 times greater than in nontreated solutions and pulps, which indicated that the sorption capacity of resins is used to the full extent. Introduction of special treatment of cyanide pulp into existing technology makes possible an efficient industrial use of commercially available weak base anion exchange resins for gold recovery.