OXIDATIVE CAPACITY OF NATIVE STRAINS FROM COPAHUE GEOTHERMAL SYSTEM IN THE PRE TREATMENT OF A GOLD SULFIDE ORE

GIAVENO A.1, CHIACCHIARINI P., CORDERO C., LAVALLE L., AND DONATI E.

BARILOCHE ARGENTINA

Simposio; 18th IBS09 International Biohydrometallurgy Symposium; 2009

CINDEFI-UNLP FI-UNCO

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:none; font-size:12.0pt; mso-bidi-font-size:10.0pt; font-family:"Courier New"; mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman"; mso-ansi-language:ES; mso-fareast-language:ES; layout-grid-mode:line;} em {font-weight:bold; font-style:normal;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> PRESENTACION DE POSTER Several reservoirs of polymetallic ores are located in Neuquén province, Patagonia Argentina. Andacollo is a gold sulfide ore coming from Andacollo area in the northwest of the province in which gold is present as submicroscopic particles contained in a pyrite matrix. Biooxidation is a well known alternative pre treatment procedure which reduces the environmental impact produced by mining activities. The aim of this work was to evaluate the oxidative capacity of native microorganisms and culture collection ones applied to a gold concentrate (68.5 g/t) from Andacollo. Biooxidation tests were carried out in shake flasks (200 rpm, 30º C and 3% w/v pulp density). The inoculums used in the experiments were: a pure culture of A. ferrooxidans DSM 11477, a pure culture of L. ferrooxidans ATCC 29047 and native mixed cultures from a natural font (Las Máquinas, Copahue). Cells were grown in specific media with iron (II) pH 1.8, with and without yeast extract. Cell concentration in solution, pH and Eh; as well as Fe, Cu and Zn were measured. Solid residues were analyzed by SEM and fluorescence microscopy with energy dispersive X-ray spectroscopy and Infrared spectroscopy (IR). Original and biooxidized samples were leached by cyanide for gold recovery. The highest percentages of solubilized iron were reached in the inoculated system (100% mixed native cultures, 63.6% collection cultures) while the dissolution in the sterile control was only 35%. The biooxided solid residues showed a decrease in the intensity of the peaks corresponding to sulphides and an increase in the peaks corresponding to sulphates (jarosite specially). Quartz and inert minerals were also found. The ore samples were leached by cyanide showing a gold recovery of 96.3 % and 45 % for the treated and untreated concentrate respectively.