Study of the recovery of Ag (I) from a zinc sulfide concentrate in S2O32- -O2 medium
Abstract
This paper presents a study of leaching of Ag (I) with sodium thiosulfate from zinc sulfide concentrate. The variables studied were the effect of temperature (298, 303, 313, 323 and 333 K) and particle size effect (-33, 33, 48, 53, 75, 106 microns) in the S2O32--O2 system. In order to detect the elemental composition and the species present in the concentrate, it was conducted chemical and mineralogical characterization of concentrate through the following techniques: Inductively coupled plasma spectroscopy (ICP), Atomic Absorption Spectroscopy (AAS), X-Ray Diffraction (XRD), Scanning Electron Microscopy-Energy-dispersive X-ray spectroscopy (SEM-EDS) and Polarization Optical Microscopy (POM). We found that the mineralogical phase containing silver is AgAsS2, same that was used to perform the thermodynamic simulation according to pH, using the software HSC Chemistry 5.11 and through the building of an Eh-pH diagram at 298 K. The experimental dissolution of Ag (I) was performed using a concentration of 0.50 M of S2O32-, a partial oxygen pressure of 1 atm and a concentration of sodium hydroxide 0.1 M (pH = 9, Eh = 1.24 volts). The effect of temperature on leaching of the precious metal was examined and a maximum dissolution of 97.42% of Ag (I) in 6 hours at 333 K and a particle size of 75 microns was examined. For the solution at different particle size, the maximum dissolution of silver at room temperature was 93% in 6 hours at a particle diameter of less than 33 microns.
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