The leaching kinetics of chalcopyrite (CuFeS2) in ammonium lodide solutions with iodine

Abstract

The leaching kinetics of chalcopyrite (CuFeS 2 ) in ammonium iodide solutions with iodine has been studied using the rotating disc method. The variables studied include the concentrations of lixiviants, rotation speed, pH of the solution, reaction temperature, and reaction product layer. The leaching rate was found to be independent of the disc rotating speed. The apparent activation energy was measured to be about 50 kJ/mole from 16 ЊC to 35 ЊC, and 30.3 kJ/mole from 35 ЊC to 60 ЊC. The experimental findings were described by an electrochemical reaction-controlled kinetic model: rate ϭ k [NH 3 ] 0.69 [OH Ϫ ] 0.42 [ ] 0.5 .Ϫ I 3

Study of the dissolution of chalcopyrite in solutions of different ammonium salts

“…This suggests that although oxidation of chalcopyrite may occur in situ as suggested by Forward and Mackiw (1955), this surface layer is in fact quite friable and would be easily abraded, hence the formation of smaller sized particles, also confirmed by the increased surface area per gram of the samples. These observations are consistent with findings by Guan and Han (1997), who identified a friable and porous surface product while oxidizing chalcopyrite in ammonia-ammonium iodide solutions. The readily soluble nature of the surface layer observed when washing the electrode layer in acid solutions indicates that this surface layer is not stable.…”

Leaching behaviour of a galvanic sludge in sulphuric acid and ammoniacal media

“…It is known that ammonium carbonate plays an important role in buffering the leaching solution, thus preventing a pH rise to the point where nickel and copper can precipitate as their hydroxides (pH beyond 10). In addition, NH 4 + ions, supplied by the ammonium salt, can favour the occurrence of amine complex reactions by removing OH − ions [7,21]. Therefore, a critical compromise between the ionic strength and pH should be found, in order to enhance the leaching efficiency of ammoniacal media for the valuable metals contained in the sludge.…”

“…After ammonia, sulphuric acid is the main solvent used in the industrial leaching of laterite, the most important nickel ore, and chalcopyrite, the major source of copper [5][6][7][8]. Jha et al [4] made an extensive review concerning several industrial hydrometallurgical processes, including leaching, to recover zinc from industrial wastes.…”

Optimization of dissolution of copper from a Nigerian goldfieldite ore for industrial utilization

“…However, numerous studies have been proposed for developing hydrometallurgical routes for leaching copper sulphide concentrates, at moderate and high reaction temperatures and pressure. Several leaching techniques, such as ammoniacal systems [10,11], acid sulphate systems [12,13], chloride systems [14,15], nitrate systems [16], etc., have been examined. Thus, ammoniacal leaching has been commonly applied for the processing of non-ferrous metals from oxide ores and thereby allows for the maximum dissolution of the metal of interest leaving behind associated impurities including iron.…”