Alternative processes for treatment of chalcopyrite —A review

Amongst the alternative processes to treat chalcopyrite, the hydrometallurgical routes without pretreatment and with pretreatment, such as oxidative roasting are considered quite attractive. Investigation of direct leaching processes involving different lixiviants such as sulphuric acid, chloride, nitric acid, ammoniacal solution and biological systems have been summarised highlighting the major development in the recent past. The problem associated with the iron dissolution in these processes calls for adequate purification and control methodology before recovery of the metal by electrowinning. Sulphation roasting is one of the important pretreatment techniques that may be adopted to recover copper from the sulphides. The iron control problem can be obviated to a great extent by choosing conditions for the sulphation roasting to produce water soluble copper sulphate and converting iron to its insoluble oxides. Another aspect of the sulphation roasting process is its suitability for smaller, pocket and complex deposits with less air pollution due to fixation of sulphur with metal. This review summarises the work carried out on oxidative roasting of chalcopyrite and related constituents such as copper sulphide and iron sulphide. Factors which have a bearing on the process, such as kinetics and mechanism of reactions and roasting in presence of additives using different oxidants are summarised Research on thermal analysis and the use of the fluidised bed reactor are also described.