New biodegradable leaching agents for recovery of rare earth elements (REE) from ion adsorption clay deposit (IAC) in north west Madagascar

IAC’s are the world's main source of heavy rare earth elements. In situ leaching is the most common extraction technology for REE from IAC's but it is responsible for tremendous environmental damages. New biodegradable leaching agents were tested to extract REEs from an IAC from Madagascar. They are culture broths of S. urea, Y. lipolytica, and B. licheniformis. The culture broth of Y. lipolytica, containing tricarboxylic acids, revealed a generally low recovery except for Gd. Pr and Dy were selectively leached by the broth of S. urea. The highest recovery of REE was achieved by the B. licheniformis culture.