Fe³⁺-Fe²⁺ Redox Cycle Peculiarity in the Acid Dissolution of Copper-Cobalt Complex Ores

Cobalt, naturally found in association with copper, as it is the case in the copper-cobalt bearing minerals from the African Copperbelt region, as found in the DRC-Zambia chain, has been often considered as a by-product from copper extraction. With Co(III) in the ore, the hydrometallurgical processing of such an ore goes through the use of reducing agents as metabisulfite and sulfur dioxide at a time preceded by a microwave energy pretreatment. The abovementioned processing leads to the inevitable release of sulfur dioxide into the environment with the expected negative impacts. This chapter discusses a polluting reagent free copper-cobalt complex oxide and sulfide ores acid green dissolution process.The use of the polluting reducing agents has been substituted by leveraging on the Fe³⁺-Fe²⁺ in-situ redox cycle. Starting with an overview of conventional dissolution processes, the chapter emphasizes on the sound thermodynamics study of the ‘mineral-mineral’ process to discuss the development of this Co(III) ecofriendly dissolution from complex copper-cobalt ores, before ending with typical examples.