Efficient gold-cyanide recovery from activated carbon by electrocoagulation technology

Abstract

Mexico is the 9th largest world gold producer with 1016 tonnes in reserves as of 2024. 41 % losses of gold with an average consumption of 40 g/t, is due to the escape of fine AC particles because they do not have the scope to prevent the loss of particles below 0.40 mm. The recovery of gold in Mexico is becoming more important. Given the low quantities of this metal present in the mineral ore and the difficulty of its extraction due to its encapsulation in its mineralogy, recoveries are low. Adsorption processes with activated carbon (AC) in the mining-metallurgy industry include phases that diminish the particle durability, coupled with its nature as organic matter, which tends to deteriorate and disintegrate in the adsorption systems. In this study, Electrocoagulation (EC) technology is shown as a better option to increase the efficient recovery of gold impregnated in extremely fine AC particles, without the use of chemical reagents in the metallurgical systems, by recovering the fine particles loaded with gold, EC tests were done on a batch pilot scale, on AC particles of 0.106 mm and 0.053 mm, using iron and aluminum electrodes with the best variables determined, they were interpolated at an industrial level. The trend that has been noticed is that smaller particles stick together to generate larger particles that contain aluminum hydroxide species. This means that using EC to recover incredibly fine AC particles is viable. Finally, the EC system with aluminum (Al) and iron (Fe) electrodes shows AC recoveries with gold were greater than 96 % and 88 % respectively. This study is a green technology for the effective recovery of gold, and cyanide in activated carbon thereby in increasing gold productivity in Mexico and the global market.

Keywords

• Electrocoagulation
• Activated carbon
• Gold
• ADR plants