Gold Recycling Through Oxidative Dissolution

Application ID: 102051

Recovery of precious metals in recycling of electronics, or extraction from ore, is usually performed through leaching of the metal into an aqueous phase. Precious metals require the use of an oxidant, and often, a complexant. In the case of gold, the cyanide anion (CN-) forms a soluble complex with gold(I) (i.e. Au(CN)-2), that is so stable that molecular oxygen becomes a viable oxidant. The process is known as gold cyanidation, and it has—unsurprisingly—been studied extensively for the past century. The model studies the oxidative dissolution of this noble metal in an air saturated cyanide solution. The system encompasses three phases: a gaseous phase (air), an aqueous phase, and a solid gold phase. We assume that the system is homogeneous on a macroscopic scale, e.g. fine particulate matter dispersed in water, which is continuously agitated by a stream of air bubbles.

This model example illustrates applications of this type that would nominally be built using the following products: