Lithium recovery from lithium-containing micas using sulfur oxidizing microorganisms

Abstract

There is about 60,000 t of lithium mica in the German part of the deposit in the Erzgebirge mountains. Lithium can be recovered by high pressure-high temperature leaching with sulfuric acid and further hydrometallurgical processing. Another idea, developed in the EU-project FAME, was to use sulfur oxidizing microbes to produce sulfuric acid and to extract lithium at moderate temperature and pressure conditions. Experiments were carried out in 2L and 4L batch reactors at 30°C. After microbial transformation of elemental sulfur to sulfuric acid, the milled (<45µm) lithium mica was added at a pulp density of 5%. Up to 26% of lithium was extracted biologically compared to 16% by chemical leaching. The bioleaching solution contained about 1g/L aluminium, 0.8g/L iron and 0.2g/L lithium and could be further processed hydrometallurgically.