Effect of glycine on bioleaching of rare earth elements from Western Australian monazite by heterotrophic and autotrophic microorganisms

The conventional hydrometallurgical recovery of rare earth elements (REEs) through highly basic and acidic processes is known to lead to many challenges including the production of toxic waste. An alternative process for bioleaching REEs from three different grades of monazite using heterotrophic (Enterobacter (E.) aerogenes) or autotrophic (Acidithiobacillus (A.) ferrooxidans) microorganisms in the presence of a benign biodegradable lixiviant, glycine (1 g L−1) was studied and evaluated. The combination of E. aerogenes and A. ferrooxidans and glycine decreased REEs bioleaching from monazite as compared to abiotic leaching or bioleaching in the absence of glycine.