Destruction of Cyanide Complex for Recovery of Gold and Silver from Minerals and Industrial Effluent by Electrocoagulation Technology

Abstract

At present, Zinc-dust cementation for gold and silver recovery is one of the most common contact-reduction processes in the Metallurgical industry. However, this reaction can extremely efficient but sensitive to oxygen and suspended solids, which makes the solution clarification to be required before the recovery of gold and silver. As a result, this technology is less competitive with other process technology. This is the reason that we propose in this study to simultaneously recapture gold and silver from the cyanidation process by electrocoagulation technology and by decreasing the pH to 8, injecting air into the electrolytic cell, and bubbling HCN(gas) in sodium hydroxide solution we can regenerate the sodium cyanide. Electrocoagulation (EC), an emerging technology mainly used for wastewater treatment, was successfully applied for this achievement. This study will introduce the fundamental concepts of the EC method for recovering gold/silver metals from cyanide solutions. In this research X-ray Diffraction, Scanning Electronic Microscope, and A A were used to characterize the solid products formed during the EC process. The results suggest that magnetite particles and amorphous iron oxyhydroxides are present. Finally with use of EC technology, the recovery of gold, silver and cyanide was 97 % in 5 minutes.

Keywords: electrocoagulation, gold, silver, cyanide, basic medium, Recovery, sustainability.