Use of Phosphate Solubilizing Bacteria to Leach Rare Earth Elements from Monazite-Bearing Ore

Abstract

Abstract:In the present study, the feasibility to use phosphate solubilizing bacteria (PSB) to develop a biological leaching process of rare earth elements (REE) from monazite-bearing ore was determined. To predict the REE leaching capacity of bacteria, the phosphate solubilizing abilities of 10 species of PSB were determined by halo zone formation on Reyes minimal agar media supplemented with bromo cresol green together with a phosphate solubilization test in Reyes minimal liquid media as the screening studies. Calcium phosphate was used as a model mineral phosphate. Among the test PSB strains, Pseudomonas fluorescens, P. putida, P. rhizosphaerae, Mesorhizobium ciceri, Bacillus megaterium, and Acetobacter aceti formed halo zones, with the zone of A. aceti being the widest. In the phosphate solubilization test in liquid media, Azospirillum lipoferum, P. rhizosphaerae, B. megaterium, and A. aceti caused the leaching of 6.4%, 6.9%, 7.5%, and 32.5% of calcium, respectively. When PSB were used to leach REE from monazite-bearing ore, ~5.7 mg/L of cerium (0.13% of leaching efficiency) and ~2.8 mg/L of lanthanum (0.11%) were leached by A. aceti, and Azospirillum brasilense, A. lipoferum, P. rhizosphaerae and M. ciceri leached 0.5-1 mg/L of both cerium and lanthanum (0.005%-0.01%), as measured by concentrations in the leaching liquor. These results indicate that determination of halo zone formation was found as a useful method to select high-capacity bacteria in REE leaching. However, as the leaching efficiency determined in our experiments was low, even in the presence of A. aceti, further studies are now underway to enhance leaching efficiency by selecting other microorganisms based on halo zone formation.

Bio-Reclamation of Strategic and Energy Critical Metals from Secondary Resources

“…After a prolonged time (over 3 days) it slowed down due to the buffering effect of weak acids. Similar trends on pH profile with in-situ production of organic acids in the bioleaching of electronic waste, red mud, cracked catalysts and monazite ores have been observed in earlier studies [28,[33][34][35][36]. Reed et al [36] reported that 60% of the organic acids, mainly gluconic acid, can be produced within the initial 24 h. Using the isolated microbial culture BH1, Acinetobacter calcoaceticus GSN8; BH24, Pseudomonas frederiksbergensis 37; and A1, Talaromyces purpureogenus for producing gluconic acid were however less effective in bioleaching of REE than the bacterium Gluconobacter oxydans.…”

Novel Biotechnological Approaches for the Recovery of Metals from Primary and Secondary Resources

“…For example, Hassanien et al (2014) used heterotrophic microorganisms such as Aspergillus ficuum and Pseudomonas aeruginosa for the bioleaching of REE from Egyptian monazite, reaching high leaching efficiencies of up to 60.6% and 52.6% by A. ficuum and P. aeruginosa, respectively [33]. In a very recent study, Shin et al (2015) investigated the ability of different phosphate-solubilizing bacteria to leach REE from monazite-bearing ores. Although the bioleaching efficiencies were very low (up to 0.13% in case of Ce), the study proved the general suitability of phosphate-solubilising bacteria to degrade highly resistant monazite ores [34].…”

“…In a very recent study, Shin et al (2015) investigated the ability of different phosphate-solubilizing bacteria to leach REE from monazite-bearing ores. Although the bioleaching efficiencies were very low (up to 0.13% in case of Ce), the study proved the general suitability of phosphate-solubilising bacteria to degrade highly resistant monazite ores [34].…”

Experiences and Future Challenges of Bioleaching Research in South Korea

“…Similarly, several scholars are using cutting-edge technology to understand the irrigation and colonization of bio-heaps [110,111]. On the other hand, studies on the bioleaching from polymetallic sources and of rare elements are also part of the scientific discussion [112,113].…”