The use of a novel oxime derivative [Phenyl(N-methylaniline)ketooxime] as leach reagent in the Copper(II) hydrometallurgy

Phenyl(N-methylaniline)ketooxime, (HL), has been designed and synthesized at the Chemical Engineering Research Center-UNSA, following the structural pattern of the LIX compounds, with a yield of 85%. The novel oxime derivative (HL) has been characterized through its physical and physicochemical properties such as: melting point (245-248 degreesC), solubility in water (ca. 2.0 g/l), protonation constant (log K-p, 5.7 in methanol), and an absorption maximum (lambda(max)) in the UV visible spectra, at 365 nm, in methanol solution. Results obtained from leach experiments indicate that the novel oxime derivative in alkaline and hypochlorite aqueous solution solubilises copper selectively in the form of a neutral copper(II) complex (CuL2), which remained stable during the experimental period in a pH range between 9 and 11 and redox potential (E-h) range between -0.145 and 0.047 V. The aqueous blue-purple copper(II) complex solution was characterized from its absorption spectra, showing a single peak at lambda(max) = 610 nm. The use of the novel oxime derivative in the leaching process has enabled the copper to concentrate from 0.82% in the ore to ca. 6.0 g/l in the pregnant leaching solution. On the other hand, electrowinning of the leach liquors has enabled the recovery of the copper and the release of the novel oxime derivative as a spent electrolyte, which was reused in a new leach process batch. Finally, by using Phenyl(N-methylaniline)ketooxime for copper hydrometallurgy, it is possible to propose an extraction process, which involves just two stages: leaching and electrowinning, thus requiring lower capital cost and energy consumption. (C) 2004 Elsevier Ltd. All rights reserved.