M. Allameh, M.R. Hosseini, E. Azimi, Development of a sustainable alternative for the ammoniacal cyanidation of copper-gold ores through a biological approach, Journal of Sustainable Metallurgy (2020) 6: 796–808.

Due to the problems arising from the presence of copper in the gold cyanidation process, including high cyanide consumption and occupation of the activated carbon surface, biological ammoniacal cyanidation was implemented as a resolution. Bacillus megaterium was implemented to produce cyanide and ammonia in nutrient broth and vinasse media. Maximum cyanide concentrations of 29.8 and 47.5 mg/L were produced using 3 g/L glycine in the mentioned media, respectively. Afterward, the Box-Behnken experiment design method was implemented to optimize ammonia biogenesis in vinasse culture, where 1974 mg/L ammonia was synthesized at 13.56 g/L calcium chloride, 7.2 g/L urea, and pH = 7.9. Three different strategies, namely: (1) bio-cyanidation, (2) bio-ammoniacal cyanidation, and (3) bio-ammonia pretreatment/bio-cyanidation, were employed to recover gold and …