INFLUENCE OF Cu~(2+) AND Zn~(2+) ON THE DISSOLUTION OF Ag IN S_2O_3~(2-) MEDIUM

摘要

The dissolution of Ag contained in metallurgical tailings was studied by adding ions Cu~(2+) and Zn~(2+) in S_2O_3~(2-) medium. Chemical analysis of mine tailings by cupellation revealed a Ag concentration of 71 g/ton. The XRF and XRD analysis confirmed the preponderance of SiO_2 in the mineral matrix. The experimental dissolution process was conducted in alkaline solution using six concentrations of NaOH and five of S_2O_3~(2-), at different temperatures, also using five concentrations of Cu~(2+) and Zn~(2+) as a catalyst. The results showed similar values for both systems (96.8% and 97.13%). The ion Cu~(2+) and Zn~(2+) increases the dissolution of Ag, and decrease the reaction time of dissolution. Under the conditions used, pH and stirring rate did not affect the dissolution of Ag.