Leaching of Refractory Gold Telluride Ore using Choline Chloride-Ethylene Glycol

Processing refractory gold telluride ores presents a major challenge in conventional cyanidation because gold occurs as particles locked within sulfides, restricting contact with the lixiviant, and as gold tellurides that are insoluble in cyanide. To address this, alternative lixiviants such as deep eutectic solvents (DES) are being explored as gold ores become increasingly complex. This study investigates the leaching behavior of refractory gold telluride ore using ethaline or choline chloride–ethylene glycol, a type of DES, prepared at a 1:2 molar ratio. Leaching experiments were conducted at varying times (24, 48, and 72 hours), temperatures (30 °C and 55 °C), and particle sizes (37 µm and 74 µm), with a constant lixiviant-to-solid ratio of 1:10, 0.1 M iodine as oxidant, and agitation at 300 RPM. Gold concentration in the leachate was analyzed using Atomic Absorption Spectroscopy (AAS) to determine the percentage of gold dissolution. Results indicate that temperature had minimal effect on gold dissolution, suggesting that leaching can be effectively performed at ambient temperature. However, particle size and leaching time significantly influenced dissolution, with higher gold dissolution observed for smaller particles. Gold dissolution increased over time, reaching a maximum of 57% at 48 hours, followed by a decline, emphasizing the need to optimize leaching duration. Overall, results demonstrate that choline chloride–ethylene glycol is able to leach refractory gold telluride ores and may be an alternative to conventional cyanidation method.