Copper removal from cyanide solutions by

Cyanidation is the predominant method for recovering gold and silver from ores, but it presents challenges when other metals, such as copper, dissolve in the process. This work explores the influence of copper on the extraction efficiency of precious metals, particularly when copper concentrations reach up to 1000 mg/L, which complicates process control and increases operational costs. The primary objectives of this study were to assess the interference of copper–cyanide complexes during the titration of free cyanide and to develop a novel method for the effective removal of copper from cyanidation solutions. This method involves acidifying the cyanide solution using sulfuric acid and subsequently filtering out the precipitated copper cyanide complex. A detailed discussion on the thermodynamics of the copper-cyanide system is provided, along with an evaluation of hydrogen cyanide (HCN) evolution at varying pH levels. Results indicate that a significant proportion of cyanide measured during titration corresponds to copper–cyanide complexes, suggesting that approximately 10% of the free cyanide quantified can be attributed to copper interactions in typical cyanide/copper ratios encountered in cyanidation practices. This research offers a promising approach to enhance the efficiency of gold and silver extraction processes.