Using native microorganisms for zinc recovery from Gualcamayo ore

MARCHEVSKY N.,; BERNADELLI C.; DONATI E.R.

SAN LUIS

Congreso; XXX Reunión Anual de la Sociedad de Biología de Cuyo; 2012

Biomining, the use of micro-organisms to recover precious and base metals from mineral ores and concentrates, has developed into a successful and expanding area of biotechnology. These processes employ microbial consortia that are dominated by acidophilic, autotrophic iron- or sulfur-oxidizing prokaryotes. A native consortium was artificially prepared using microorganisms from different samples taken in an acid mine drainage of La Esperanza Mine (La Carolina, Province of San Luis). This consortium was used in the bioleaching of Gualcamayo ore (Province of San Juan). The experiments were conducted in flasks containing mineral finely ground at a pulp density of 2% (w/v). Basal salt medium at pH 1.8 was used with or without Fe(II) 1 g/L, powder sulphur 0.67% w/v and/or yeast extract 0.02% w/v. Samples were withdrawn at regular intervals for measuring pH and Eh. Fe(II) concentration was measured using ortofenantroline spectrophometric method. Iron and zinc concentrations were determined by atomic absorption spectrophotometry. At 27 days, the culture in basal medium with and without iron achieved a maximum zinc recovery closed to 100% while the sterile controls reached less than 80% in all cases.