Recovery of gold and silver from slag from the "La Herradura" unit; effect of zinc during leaching in the thiosulfate-ammonia-Cu(II) (TACu) system

• DOI: https://doi.org/10.22533/at.ed.317572517073

• Palavras-chave: Au-Ag smelting slag, TACu(II),

• Keywords: Au-Ag smelting slag, TACu(II),

• Abstract:

  The gold and silver contained in the smelting slag from the La Herradura unit, in concentrations of 168 g Au/ton and 437 g Ag/ton, are present in a metallic state, mainly as Au-Ag (75%) and Au-Ag-Cu (22%) with spherical or rounded shapes, of the type that causes fusion and solidification. Most of these are associated with zinc silicate particles, mainly as inclusions (12 microns), followed by simple bonds at the edges of the zinc silicate particles.
  The results of gold dissolution rates in slag in the Thiosulfate-Ammonia-Cu(II) (TACu) system, based on solution analysis via atomic absorption, indicate that these are higher than those obtained in cyanide. The presence of zinc ions (100, 200, and 400 ppm), in accordance with their hard-soft nature, increases the dissolution rate. However, it should be emphasized that the size of metal inclusions and the composition of the slag are factors to be considered in the chemistry of a leaching system, which is characterized by its complexity and stability.