Recent Applications of Peroxygen Reagents in Hydrometallurgy

Abstract

The paper reviews development made over the past decade in the application of peroxygnn reagents in hydrometallurgical processes. The reagents are hydrogen peroxide, H₂0₂, Caro’s acid, H_2MS0₅, and calcium peroxide, CaO₂. Their chemical properties and methods for on-site storage or production are outlined.

Most progress has been made in the gold extraction industry, where hydrogen peroxide and calcium peroxide have been used to enhance oxygen availability in the cyanide leaching of gold ores, in both agitated and heap leach systems. Properly controlled, the use of these reagents can lead to increased rates of gold extraction and savings in cyanide consumption. Hydrogen peroxide is also widely applied for the oxidative destruction of cyanide in gold mill effluent solutions and tailings ponds. Caro’s acid can also be used for this purpose, with advantage in certain situations, which arc discussed. Caro’s acid has found industrial application in the leaching of uranium ores in Australia at the Nabarlek mine and this operation is described. Other applications discussed include the separation of cobalt from nickel by oxidative hydrolysis with Caro’s acid and the reclamation and recycle of tungsten using hydrogen peroxide.