Embodiments of the present disclosure generally relate to the recovery and extraction of rare earth elements. More specifically, embodiments of the disclosure relate to methods for separating rare earth elements from coal, coal by-product(s), and/or coal-derived product(s). In an embodiment, a method of removing rare earth elements from a coal-derived product is provided. The method generally includes introducing supercritical CO.sub.2 to the coal ash to form a first mixture, introducing a first acid to the first mixture to form a second mixture, and removing a first composition from the second mixture, the first composition comprising the one or more rare earth elements.

Embodiments of the present disclosure generally relate to the recovery and extraction of rare earth elements. More specifically, embodiments of the disclosure relate to methods for separating rare earth elements from coal, coal by-product(s), and/or coal-derived product(s). In an embodiment, a method of removing rare earth elements from a coal-derived product is provided. The method generally includes introducing supercritical CO.sub.2 to the coal ash to form a first mixture, introducing a first acid to the first mixture to form a second mixture, and removing a first composition from the second mixture, the first composition comprising the one or more rare earth elements.

A method of recovering a rare earth metal can include incubating a bacterial consortium in the presence of a rare earth metal source comprising a rare earth metal and iron. The bacterial consortium can include an acid secreting bacterium, a heavy metal resistant bacterium, an iron-sequestering molecule secreting bacterium, and a rare earth metal sequestering bacterium. The method can further include: producing an acid using the acid secreting bacterium; leaching iron and the rare earth metal from the rare earth metal source using the acid; protecting the bacterial consortium from metal using the heavy metal resistant bacterium; sequestering iron using the iron-sequestering molecule secreting bacterium; and sequestering the rare earth metal using the rare earth metal sequestering bacterium

A method of recovering a rare earth metal can include incubating a bacterial consortium in the presence of a rare earth metal source comprising a rare earth metal and iron. The bacterial consortium can include an acid secreting bacterium, a heavy metal resistant bacterium, an iron-sequestering molecule secreting bacterium, and a rare earth metal sequestering bacterium. The method can further include: producing an acid using the acid secreting bacterium; leaching iron and the rare earth metal from the rare earth metal source using the acid; protecting the bacterial consortium from metal using the heavy metal resistant bacterium; sequestering iron using the iron-sequestering molecule secreting bacterium; and sequestering the rare earth metal using the rare earth metal sequestering bacterium

Mixed rare earth carbonate may be prepared by mixing a rare earth sulfate solution with a precipitating agent comprising a first sodium carbonate (Na.sub.2CO.sub.3) solution, to form a first mixture, and generating a higher sulfate rare earth carbonate wet cake from the first mixture. The higher sulfate rare earth carbonate wet cake can be mixed with a second sodium carbonate (Na.sub.2CO.sub.3) solution to form a second mixture, and a lower sulfate rare earth carbonate can be generated from the second mixture.

Mixed rare earth carbonate may be prepared by mixing a rare earth sulfate solution with a precipitating agent comprising a first sodium carbonate (Na.sub.2CO.sub.3) solution, to form a first mixture, and generating a higher sulfate rare earth carbonate wet cake from the first mixture. The higher sulfate rare earth carbonate wet cake can be mixed with a second sodium carbonate (Na.sub.2CO.sub.3) solution to form a second mixture, and a lower sulfate rare earth carbonate can be generated from the second mixture.

Provided herein are methods recovering rare earth elements (REEs) from a solution containing one or more REEs. These methods can comprise contacting an aqueous solution comprising one or more rare earth elements (REEs) with a solid sequestration media (e.g., a stabilized flue gas desulfurization (sFGD) material, or a sludge by-product from a water treatment process) to provide a REE-containing solid feedstock; and contacting the solid feedstock with an extraction solution to generate a rare earth element (REE) solution.

Provided herein are methods recovering rare earth elements (REEs) from a solution containing one or more REEs. These methods can comprise contacting an aqueous solution comprising one or more rare earth elements (REEs) with a solid sequestration media (e.g., a stabilized flue gas desulfurization (sFGD) material, or a sludge by-product from a water treatment process) to provide a REE-containing solid feedstock; and contacting the solid feedstock with an extraction solution to generate a rare earth element (REE) solution.

Mixed rare earth carbonate may be prepared by mixing a rare earth sulfate solution with a precipitating agent comprising a first sodium carbonate (Na.sub.2CO.sub.3) solution, to form a first mixture, and generating a higher sulfate rare earth carbonate wet cake from the first mixture. The higher sulfate rare earth carbonate wet cake can be mixed with a second sodium carbonate (Na.sub.2CO.sub.3) solution to form a second mixture, and a lower sulfate rare earth carbonate can be generated from the second mixture.

Mixed rare earth carbonate may be prepared by mixing a rare earth sulfate solution with a precipitating agent comprising a first sodium carbonate (Na.sub.2CO.sub.3) solution, to form a first mixture, and generating a higher sulfate rare earth carbonate wet cake from the first mixture. The higher sulfate rare earth carbonate wet cake can be mixed with a second sodium carbonate (Na.sub.2CO.sub.3) solution to form a second mixture, and a lower sulfate rare earth carbonate can be generated from the second mixture.