(Session 6)Assessment of Bacterial and Fungal Mediated Bioleaching of Alkaline Materials towards Alteration and Solubilisation of Mineral Phases

摘要

Bioleaching is a potential route for the valorisation of alkaline materials (natural and waste),and may serve as a pre-treatment stage to mineral carbonation and/or sorbent synthesisprocesses, due to the increased surface area and altered mineralogy of the solid material andthe generation of an alkaline rich (Ca and Mg) aqueous stream. The bioleaching potential ofseveral bacteria (Bacillus circulans, Bacillus licheniformis, Bacillus mucilaginosus,Sporosarcina ureae) and fungi (Aspergillus niger, Humicola grisea, Penicilliumchrysogenum) towards the solubilisation and alteration of mineral phases contained in purealkaline materials (wollastonite and olivine) and alkaline waste residues (AOD and BOF steelslags, and MSWI boiler fly ash) were assessed. Bioleaching is conducted using one-step andtwo-step methodologies in this work. Positive results with respect to increased solubilisationof alkaline earth metals, and the alteration of basicity, mineralogy and morphology of thesolid materials were obtained. The similarities between fungal and bacterial mediatedbioleaching suggest that biogenic substances such as organic acids and exopolysaccharidescontribute mostly to these effects.