The present disclosure discloses a method for preparing rare earth oxide by recycling ammonia and carbon, comprising the steps of: (1) heating raw materials containing a first rare earth carbonate and a first rare earth oxide with microwave and calcining at 500-1000 C. for 20-120 min to obtain a second rare earth oxide and carbon dioxide; (2) reacting carbon dioxide with a first ammonia water to obtain a precipitant; (3) reacting the precipitant with rare earth chloride to obtain a second rare earth carbonate and ammonium chloride wastewater. In the method, calcination time is short, rare earth recovery rate, utilization rate of ammonia and carbon resources are high. The present disclosure also provides a use of a rare earth oxide in shortening calcination time and/or increasing rare earth yield.

Systems and methods herein provide for Rare Earth Element Extraction and Recycling (REEER). One system extracts and recovers rare earth elements (REEs) from magnet-containing feedstock using a leaching reactor, an oxidizing gas, and a carbonate-based leaching solution. The leaching reactor selectively dissolves non-rare-earth constituents and produce a leachate comprising dissolved species and solid rare earth residues. The system also comprises a solid-liquid separation subsystem to separate solid residues from the leachate, and a precipitation subsystem to precipitate rare earth carbonate solids. The system also comprises a filtration and washing subsystem to recover and purify the rare earth carbonate solids, a regeneration subsystem to react the solution with carbon dioxide to reform the carbonate leaching agent for reuse. A process control system manages the flows among the leaching reactor, precipitation subsystem, regeneration subsystem, such that the system operates in a closed-loop manner with minimal reagent loss and high-purity REE product recovery.

Systems and methods herein provide for Rare Earth Element Extraction and Recycling (REEER). One system extracts and recovers rare earth elements (REEs) from magnet-containing feedstock using a leaching reactor, an oxidizing gas, and a carbonate-based leaching solution. The leaching reactor selectively dissolves non-rare-earth constituents and produce a leachate comprising dissolved species and solid rare earth residues. The system also comprises a solid-liquid separation subsystem to separate solid residues from the leachate, and a precipitation subsystem to precipitate rare earth carbonate solids. The system also comprises a filtration and washing subsystem to recover and purify the rare earth carbonate solids, a regeneration subsystem to react the solution with carbon dioxide to reform the carbonate leaching agent for reuse. A process control system manages the flows among the leaching reactor, precipitation subsystem, regeneration subsystem, such that the system operates in a closed-loop manner with minimal reagent loss and high-purity REE product recovery.

Despite the abundance of scandium, its commercial applications continue to be limited by the absence of reliable, secure, stable and long-term production. The subject-matter disclosed herein provides for a method for extracting Rare Earth Elements (REE), scandium and/or Rare-Earth Oxides (REO) from ore and mineral concentrates, the method comprising: providing Rare Earth Elements (REE) and/or scandium bearing feedstock; a high-pressure caustic (HPC) leaching step, comprising leaching the feedstock in an alkali solution at a first temperature for a target period of time and at a given pressure to produce a leachate slurry; extracting a solid residue from the leachate slurry; leaching of the solid residue in a mineral acid to form a primary leach solution; extracting scandium and/or REE from the primary leach solution; and/or precipitating REE remaining in the raffinate to form a mixed REE-carbonate to thereby facilitate the extraction of REO.

Despite the abundance of scandium, its commercial applications continue to be limited by the absence of reliable, secure, stable and long-term production. The subject-matter disclosed herein provides for a method for extracting Rare Earth Elements (REE), scandium and/or Rare-Earth Oxides (REO) from ore and mineral concentrates, the method comprising: providing Rare Earth Elements (REE) and/or scandium bearing feedstock; a high-pressure caustic (HPC) leaching step, comprising leaching the feedstock in an alkali solution at a first temperature for a target period of time and at a given pressure to produce a leachate slurry; extracting a solid residue from the leachate slurry; leaching of the solid residue in a mineral acid to form a primary leach solution; extracting scandium and/or REE from the primary leach solution; and/or precipitating REE remaining in the raffinate to form a mixed REE-carbonate to thereby facilitate the extraction of REO.