Diagnostic pre-treatment procedure for simultaneous cyanide leaching of gold and silver from a refractory gold/silver ore

This study investigates the optimization of simultaneous dissolution of gold and silver from a refractory gold ore through determination of pre-treatment stages. Based on the mineralogical studies (thin layer and polished section) and chemical analysis on the ore sample, a “diagnostic leaching” procedure was designed. Results from diagnostic leaching suggest that the most effective pre-treatment agents for gold and silver are ferric chloride and sulfuric acid media, respectively. Optimum conditions for the simultaneous dissolution of gold and silver were determined using a two factorial design technique. Pre-treatments with sulfuric acid and ferric chloride reagents increased the efficiency of the dissolution of gold from 54.7% to 82% and silver from 37.4% to 81.6%.

Using mineralogical analysis and a diagnostic leaching design procedure, four reagents were used to recover 98.1% Au and 99.8% Ag.Figure optionsDownload as PowerPoint slideHighlights
► Mineralogical analysis and diagnostic leaching were used for characterization.
► Four leaching reagents were used to recover 98.1% Au and 99.8% Ag.
► Two factorial design and ANOVA to optimize simultaneous dissolution of Au and Ag.
► Pre-treatments with ferric chloride and sulfuric acid increased the dissolution.
► Cyanide dissolution efficiency increased: Au, 54.7–82% and Ag, 37.4–81.6%.