Zinc recovery during refractory ore biooxidation by an indigenous consortium

MARCHEVSKY N; URBIETA, MARIA SOFIA; BERNARDELLI C.,; MAS, MIGUEL; DONATI, EDGARDO

INTERNATIONAL JOURNAL OF MINERAL PROCESSING

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 p. 30 - 37

0301-7516

Two enrichment cultures (one iron oxidizing and one sulfur oxidizing) obtained froman acid mine drainage were physiologically and molecularly characterized; the first of them showed 99% 16S rRNA gene sequence similarity with Leptospirillum ferrooxidans, while the sulfur oxidizing species was highly related to Acidithiobacillus ferrooxidans and Acidithiobacillus ferrivorans sequences although, unlike them, the species in the enrichment culture does not seem to be able to oxidize iron. The consortium constituted by both enrichment cultures achieved a successful biooxidation of Hualilan ore allowing the increase of gold recovery up to 96.4% in the best culture condition (low pulp density in 1 K medium). At the same time, this condition showed an effective zinc bioleaching (up to 86%) although the recovery was much higher in cultures with initially supplemented iron; kinetics studies suggested that the bioleaching rate in 1 K medium at low pulp densities is controlled by diffusion through a layer mainly constituted by jarosite (rather than sulfur)whichwas detected in X-ray diffractiondiagrams. The recovery of zinc as a subproduct of the pretreatment to optimize gold recovery would also allowthe decrease of the metallic charge of the leachates from the biooxidation tanks which is an environmental advantage.