Lithium Bioleaching from Lepidolite Using the Yeast Rhodotorula Rubra

Abstract

In this present work lithium recovery from lepidolite (3.79% Li 2 O) by bioleaching was investigated. Lithium due to its electrochemical reactivity and also other unique properties has attracted much attention for their application in many industrial fields such as batteries, ceramics and glass production, greases, pharmaceuticals and polymers and other uses. The tremendous growth in lithium demand for lithium batteries used in hybrid and electromobiles has raised great concern about the future availability of lithium. In nature lithium is present in a variety of aluminosilicates and continental brines. One of the principal lithium minerals in the world is lepidolite. Its destruction and consequent lithium is a high capital and energy intensive process therefore it is necessary to seek an efficient, economic technique to handle this ore. Biohydrometallurgical approaches with low energy and cost requirement are coming into perspective. Some species of bacteria, fungi and yeasts contribute to weathering processes and mineralization of metal containing materials. The most active leaching fungi such as Penicillium simplicissimum and Aspergillus nige produce great amounts of organic acids which play an important role as leaching agents in metal dissolution. However, there is a lack of studies on metal bioleaching from solid substrates using the yeast Rhodotorula rubra. In nature R. rubra may be found in silicates near lithium mining deposits. It is a slime producer and by means of macromolecules such as polysaccharides or polypeptides present in the capsule and wall can enhance silicate weathering processes. The main aim of this research work was to investigate lithium extraction from lepidolite using the yeast R. rubra and also the influence on nutrients on metabolic and leaching activity of the yeast. During the bioleaching of lepidolite using R. rubra Li extracted and accumulated in the biomass was 412.6 μg/g and 181.2 μg/g in nutrient and salt-limited medium, respectively. In leach liquor, lithium concentration was 25 μg/l and 89 μg/l in nutrient and salt-limited medium, respectively.