BIOLEACHING OF A POLYMETALLIC SULPHIDE ORE FROM CAPILLITAS (ARGENTINA)

PATRICIA CHIACCHIARINI; CORDERO CINTIA; FERRANDO AILEN; SURIN LUCÍA; GIAVENO ALEJANDRA

Cape Town

Congreso; HYDROMETALLURGY CONFERENCE 2016; 2016

The Southern African Institute of Mining and Metallurgy

The growing demand of metals due to the industrialization of new countries and theemergence of new technologies gives rise to the study and development ofnon-conventional extraction technologies. The search is focused on profitable,efficient and environmental friendly processes, where bioleaching has proven tobe a viable alternative. In particular, the bioleaching with moderately thermophilic acidophiles microorganisms is a robust choice for the exploitation of sulfide mineral deposits whose value cannot be extracted by conventional processes, oris not economically viable. Microorganisms catalyze the dissolution of metals, achieving high selectivity and efficiency related to traditionalhydrometallurgical processes. The purpose of this work was to study the bioleachingof a sulfide ore from Capillitas (Catamarca, Argentina) using definite consortiaof native mesophilic and thermophilic microorganisms conformed by iron and sulfur‐oxidizing ones and heterotrophic microorganisms. The mixed mesophilic consortium contained autotrophic microorganisms identified by their physiological, morphological and molecular characteristics as Leptospirillum ferrooxidans-like and Acidithiobacillus thiooxidans‐like. Particularly, the moderately thermophilic consortium from Copahue-Caviahue geothermal areaincluded L. ferriphilum-like, At. caldus-like and a moderately thermophilic heterotrophic acidophilic strains. The sulfide ore from Capillitas contained marcasite (FeS2), sphalerite (ZnS) and chalcopyrite (CuFeS2) as its major minerals. Bioleaching tests were performed at 30° C and 42°C in shake flasks, at pH 2.0 and 1.6, pulp density of 2% w/v and particle size<74 mm. At 42°C, Zn and Cu solubilization was 80.0 % and 98.3 % respectively (pH2.0), while at 30°C, 59.4% Zn and 72.9% Cu were solubilized (pH 2.0). Extractionsof Zn and Cu in inoculated tests were higher than in uninoculated tests underthe same conditions which highlight the roles of microorganisms in enhancing bioleaching. The moderately thermophilic consortium proved to be more efficient to bioleaching this polymetallic ore from Capillitas than the mesophilic consortium used.