title: Extraction of lithium from spodumene by bioleaching.
abstract: The recovery of lithium from spodumene (6.9% Li2O) by bioleaching was investigated. This process was carried out using heterotrophic micro-organisms previously isolated from the mineral. Penicillium purpurogenum, Aspergillus niger and Rhodotorula rubra were assayed separately. Two different media were used for bioleaching; one of them (M2 medium) was highly limited in Mg2+, Fe2+ and K+. The assays were carried out in 500 ml Erlenmeyer flasks with 1 g of ground mineral at 50-80 mesh and 150 ml of leaching medium. Lithium extracted and accumulated in biomass during 30 d of bioleaching with P. purpurogenum was 6.35 mg % dry weight (d.w.) in M1 medium and 10.8 mg % d.w. in M2 medium, while in the leach liquor, Li concentration was 1.06 ppm (M1 medium) and 1.26 ppm (M2 medium). Results of leaching on day 30 with R. rubra were 5.87 mg % d.w. and 16.7 mg % d.w. of lithium accumulated in biomass in M1 medium and M2 medium, respectively. In leach liquor, lithium was 0.5 ppm (M1 medium) and 1.53 ppm (M2 medium). Aspergillus niger was able to accumulate 1.60 mg % d.w. (M1 medium) and 5.1 mg % d.w. of lithium (M2 medium) in biomass. Lithium in leach liquor was 0.37 ppm (M1 medium) and 0.75 ppm (M2 medium). Chemical analysis of the leach liquor showed gluconic and citric acids. It was possible to detect capsular exopolymers in the yeast. These metabolic products seem to be related to leaching but a more important factor for enhancing this process may be microbial adaptation to a low nutrient environment.
authors.affiliation: Cátedra de Química Biológica, Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Argentina.
authors.forename: I
authors.initials: I
authors.lastname: Rezza
authors.forename: E
authors.initials: E
authors.lastname: Salinas
authors.forename: V
authors.initials: V
authors.lastname: Calvente
authors.forename: D
authors.initials: D
authors.lastname: Benuzzi
authors.forename: M I
authors.initials: MI
authors.lastname: Sanz de Tosetti
mesh_terms: D001234:Aspergillus niger / Q000302:isolation & purification / Q000378:metabolism; D018533:Biomass; D001709:Biotechnology; D003470:Culture Media; D008094:Lithium / Q000302:isolation & purification*; D008828:Microbiological Techniques; D008903:Minerals / Q000737:chemistry*; D010407:Penicillium / Q000302:isolation & purification / Q000378:metabolism; D012248:Rhodotorula / Q000302:isolation & purification / Q000378:metabolism; D012988:Soil Microbiology
chemical_list: D003470:Culture Media; D008903:Minerals; C026378:spodumene; D008094:Lithium