Preg-robbing verification and prevention in gold chloride-bromide leaching

The current study presents an equation indicating gold loss due to preg-robbing into solids in chloride-bromide media. The equation was verified using a naturally preg-robbing gold concentrate. It was shown that the graphite naturally present in gold ore can be an equally active preg-robbing agent for gold chloride complex as industrially manufactured and commercially available activated carbon. In order to study preg-robbing prevention during gold leaching in chloride-bromide media, carbon blinding, and Cl2-pretreatment were applied. Blinding with ShellSol D70 was shown to improve gold recovery only slightly whereas Cl2-pretreatment was shown to increase gold recovery from 2% to 45% for a naturally preg-robbing gold concentrate.