II. Bioleaching of a Refractory Ore from the El Zancudo Mine

Abstract

Written by a chemical engineer from the Universidad Nacional de Colombia, Medellín campus, this article presents pre-feasibility metallurgical research on treating refractory gold-silver ores from the El Zancudo mine in Titiribí using non-Krebs-cycle bacterial bioleaching. The author explains that these ores cannot be recovered through conventional cyanidation due to the presence of cyanicide minerals, and describes the direct and indirect mechanisms of bioleaching. The text presents comparative experimental results between treatment methods: cyanidation preceded by bioleaching achieved 72.3% recovery, exceeding conventional methods by more than 35%, and documents findings suggesting potential gold yields far higher than those reported by the company currently holding the mining rights.