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Abstract

The mineralogical characterization of gold-bearing ores from the La Esperanza mine has been

conducted by studying thin sections, using petrographic microscope, and WDS and EDS chemical analyses. A total of thirty-two samples were collected directly from the La Esperanza mine and twenty samples were selected for the thin section preparation. From these analyses, 553 grains of electrum and native silver were identified, and a detailed description of these grains (assemblage, size and occurrence of each grain) was used to design a metallurgical processes to recover gold and silver from the La Esperanza ores. Fire assays revealed gold and silver contents of 219 g/t and 2702 g/t, respectively. Physicochemical characteristics such as: mineral pulp, absence of soluble salts and acid pH, indicated favorable conditions for cyanide leaching bottle. The metallurgical characterization showed a low leachability grade because the percentage of gold and silver recuperation was lower than 65%, and the size of most grains ranged between 180 m and 106m (80-140 meshes Tyler). The grain size selected for the cyanide leaching bottle test was 270 meshes Tyler (-53 μm). The statistical design analyses of the cyanide leaching bottle test revealed a recovery grade of 82,47% with a cyanide concentration of 2g/l after 12 hours, with areliability of 95%