Caracterización de residuos mineros y diseño preliminar de un sistema de acopio controlado en el distrito minero de Zaruma-Portovelo (SE Ecuador)

Abstract

Traditional mining in the Zaruma-Portovelo mining district (Ecuador) causes negative environmental impacts since significant amounts of sulfur-rich wastes (tailings) are generated and are usually released into rivers or surrounding areas. This work is based on the assumption that the geochemical-mineralogical characterization of tailings can be used to minimize the oxidation of sulfides and the acid mine drainages generation. The characterization of 3 tailings from Agapitos, Emicor and San José processing plants (acid, heterogeneous and neutral-alkaline, respectively) was carried out and they were placed in an experimental controlled storage plant covered with a reactive limestone layer to cause the formation of Fe-oxyhy-droxisulphates, which should develop a limiting layer against the waste oxidation. The results after the first rainfall support this hypothesis as Fe and S concentrations increased (20cm) above the Agapitos tailings, favouring the removal of toxic metals in deep sections of the profile. In addition, controlled storage causes, in general, the inertization of waste by sulfides encapsulation processes. The mineralogical data were congruent and new mineral phases (mainly schwertmannite and jarosite) were identified when contact occurs between the alkaline and acids materials.