Bioleaching of Major, Rare Earth, and Radioactive Elements from Red Mud by using Indigenous Chemoheterotrophic Bacterium Acetobacter sp.

Abstract

The aim was to study the bioleaching performance of chemoheterotrophic bacterium involved in leaching of major, rare earth, and radioactive elements from red mud (RM), and to explore the underlying mechanism. An acid-producing bacterium, identified as Acetobacter sp., was isolated from RM impoundment and used in the bioleaching experiments under one-step, two-step and spent medium process at up to 10% pulp density. The results showed that the leaching ratios of Al, Lu, Y, Sc, and Th were 55%, 53%, 61%, 52%, and 53% respectively under one-step process at 2% pulp density. Under both one- and two-step processes at 2% pulp density, the radioactivity of bioleached RM can meet the relevant regulation in China. The total amount of organic acids excreted by Acetobacter sp. increased with an increase of RM pulp density. After bioleaching, contents of hematite and gibbsite decreased but perovskite increased in RM. Micromorphology analysis indicated that the cells of Acetobacter sp. adhered to RM particles and formed large-size aggregates, and a new crystal of weddellite emerged. In view of the shorter lag phase and smaller biomass comparing to fungi even under direct contact with RM, bacterium Acetobacter sp. is supposed to apply to in situ heap or dump bioleaching of RM.

Study of Microbial Cultures for the Bioleaching of Scandium from Alumina Industry By-Products

“…Bioleaching is a technology considered as 'a green technology', with operational flexibility and low energy requirements [18]. Bioleaching can be performed by chemoautotrophic and chemoheterotrophic microorganisms; however, due to the highly alkaline environment of BR, chemoheterotrophics are more suitable for BR, as they have a higher tolerance to heavy metals and a faster growth and adaptation in a wide range of pHs [21,22]. Furthermore, chemoheterotrophic microorganisms can use metabolites, such as proteins and amino acids, in BR to form complexes with toxic metal ions [23].…”

Comparison of Three Approaches for Bioleaching of Rare Earth Elements from Bauxite

“…One study has considered bioreductive dissolution for leaching REE from monazite [30], leaching up to 8% La with A. thiooxidans. The red mud tailings from the processing of bauxite have been a target for the bioleaching of REE, focusing on organic acid bioleaching with heterotrophic bacteria and fungi [23,[31][32][33], and one recent study demonstrates the ability of microalgae to accumulate REE (plus Y and Sc) in quantities of up to 54.5 mg•kg −1 of dry biomass from red mud [34]. To date, unprocessed bauxite has not been targeted for REE bioleaching.…”

A State of the Art on Red Mud as a Substitutional Cementitious Material

“…The disposal of large quantities of red mud is very difficult and it leads to land, air and water pollution [11]. Because it has high alkaline nature and it contains many hazardous substances like metals and radioactive elements [12][13][14]. In the alumina production, one ton of alumina produces 1-1.5 tonnes of red mud [15].…”

“…The bauxite ore and refining process can influence the amount of red mud comes as a wastage. Many studies are done to use red mud in several industrial products such as ceramic tiles, brick manufacturing, cement production, land reclamation and others [10][11][12][13][14][15]. Also, red mud used in the treatment of waste water and exhaust gas as an adsorbent [15][16][17][18][19][20].…”