Leaching of pre-oxidated pyrargyrite with Na2S2O5

Abstract

Recently, Mexico has established itself as the largest producer of silver in the world; however, the minerals extracted have a very complex mineralogy. Pyrargyrite presents problems of leaching with cyanide. For this reason, the effect of oxidation with metabisulfite prior to leaching with cyanide is studied. The characterization of the mineral confirmed the presence of a single phase of Ag3 SbS3, identified in the pattern of DRX PDF 00-019-1135. The MEB–EDS analysis shows the elements of pyrargyrite, antimony 22.90, sulfur 17.4, and silver with 59.6%. From analysis by FTIR, the presence of antimony oxides was found and the formation of sulfates. The leaching of silver with cyanide [0.03]M pre-oxidized with metabisulfite [0.105]M and 96 h, reaches a percentage of silver extraction of 25% in 68 h. The increase in the concentration of oxidizing agent at [0.210]M and the leaching time contributes to achieve recoveries of 37%.