Regeneration of ion-exchange resins used for gold recovery

Abstract

Ion-exchange resins are currently used at gold-plating facilities to collect gold from waste solutions. The gold-containing feed solution is passed through an anion-exchange resin column where gold is adsorbed as Au(CN)2~. The present method of recovering the adsorbed gold is by drying and incineration of the resin. An alternative method involves eluting gold from the resin by use of a concentrated KSCN solution in a mixed solvent of water and DMF, followed by crystallization as potassium gold cyanide. A two-step process for regeneration of ion-exchange resins from which gold has been extracted has been developed. This process involves conversion from the initial thiocyanate form of the resin to the chloride form, followed by conversion to the hydroxide form. The operating temperature range has been determined to be 45-55 °C. Changes in flow rate and eluent concentration show little effect on the rate of thiocyanate elution.

Electrochemically Mediated Recovery and Purification of Gold for Sustainable Mining and Electronic Waste Recycling

“…20 For example, niacin has recently been demonstrated as a promising agent for gold precipitation; 21 however, high chemical consumption, high filtration costs, and narrow compositional ranges limit the applicability of precipitationbased approaches. The adsorption of gold ions from leach solutions with ion-exchange resins has long been demonstrated as a potential alternative to conventional activated carbon, boasting incredible gold uptakes of over 500 mg/g dry adsorbent, 22 but economical and efficient regeneration of ionexchange resins remains a challenging issue due to high chemical consumption and low adsorbent cyclability.…”

A Kinetic Model for Cationic-Exchange-Resin Regeneration

“…A two-step regeneration was developed for this process. The regenerants are concentrated potassium chloride followed by potassium thiocyanate solution (Sapjeta et al, 1987). Ionexchange resins used to remove nitrate from drinking water are regenerated with concentrated sodium chloride (Hoek and Klapwijk, 1989).…”