US-12624416-B2 - Rare earth laser-assisted metal production and separation

Abstract

A compound or complex containing a rare earth element is impinged with a pulsed laser that is so controlled as to photochemically reduce and obtain a rare earth metal (REM). A mixture of REM salts can be impinged using laser light tuned to selectively reduce a particular rare earth-containing salt of the mixture to separate out as its respective rare earth metal.

Inventors

• Cajetan Ikenna Nlebedim
• Abhishek SARKAR
• Pranav Shrotriya
• Denis Prodius
• Ho-Won Noh
• Thomas LOGRASSO

Assignees

• IOWA STATE UNIVERSITY RESEARCH FOUNDATION, INC.

Dates

Publication Date

20260512

Application Date

20221214

Claims (19)

1. 1 . A method of producing a rare earth metal, comprising impinging a precursor rare earth element-containing compound material in a sub-atmospheric processing chamber with a pulsed laser light controlled in a manner to reduce at least part of the rare earth element-containing compound material in the chamber to yield a rare earth metal.
2. 2 . The method of claim 1 wherein the precursor rare earth element-containing material comprises a rare earth compound or rare earth complex.
3. 3 . The method of claim 1 wherein the rare earth metal comprises at least one of La, Ce, Pr, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and/or Lu.
4. 4 . The method of claim 2 wherein the precursor rare earth element-containing compound material comprises at least one of an oxide, hydroxide, oxalate, halide or other salts of the rare earth element.
5. 5 . The method of claim 1 wherein the rare earth element-containing compound material is at ambient temperature when impinged with the pulsed laser light.
6. 6 . The method of claim 1 wherein the rare earth element-containing compound material resides as a pressed powder body in the processing chamber having sub-atmospheric pressure during impingement with the pulsed laser light.
7. 7 . The method of claim 1 wherein the pulsed laser light is scanned across the rare earth element-containing material.
8. 8 . The method of claim 1 wherein the pulsed laser light is UV to IR light.
9. 9 . A method of producing a rare earth metal, comprising impinging a mixture of different constituent rare earth element-containing materials in a sub-atmospheric processing chamber with a pulsed laser light whose wavelength is tuned in a manner to selectively reduce at least one of the constituent rare earth element-containing materials of the mixture to yield a selected rare earth metal.
10. 10 . The method of claim 9 wherein the selected rare earth metal comprises at least one of La, Ce, Pr, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and/or Lu.
11. 11 . The method of claim 9 wherein Ce metal is selectively produced.
12. 12 . The method of claim 9 wherein Pr metal is selectively produced.
13. 13 . The method of claim 9 wherein Nd metal is selectively produced.
14. 14 . The method of claim 9 wherein a metal alloy comprising Pr and Nd is selectively produced.
15. 15 . The method of claim 9 wherein La metal is selectively produced.
16. 16 . The method of claim 9 wherein the rare earth element-containing materials of the mixture comprise a rare earth oxide, rare earth hydroxide, rare earth oxalate, rare earth halide and/or other rare earth salts.
17. 17 . The method of claim 9 wherein the mixture of the rare earth element-containing materials resides as a pressed powder body in the processing chamber having the sub-atmospheric pressure during impingement with the pulsed laser light.
18. 18 . The method of claim 9 wherein the pulsed laser light is scanned across the mixture of rare earth element-containing materials.
19. 19 . The method of claim 9 wherein the pulsed laser light is UV to IR light.

Description

This invention was made with government support under Grant No. DE-AC-02-07CH11358 awarded by the U.S. Department of Energy. The government has certain rights in the invention. FIELD OF THE INVENTION The present invention relates to method and apparatus for producing a rare earth metal from a compound or complex containing a rare earth element or from a mixture thereof. BACKGROUND OF THE INVENTION Rare earth elements (REEs) are crucial for our modern society, and the resiliency of their supply chains is essential for the nation's technological advancement, energy security, economic prosperity, and defense. Electric vehicles (EVs) can significantly reduce greenhouse gasses and help achieve the transition to a net-zero economy by 2050. Still, such achievement will depend on substantial advancement in rare earth metal (REM) production technologies. Apart from their many other applications, REMs is a key component of EVs, wherein REMs are needed for the drivetrains. In 2019, 80% of REE-containing compounds consumed in the U.S. were imported. Some domestically sourced REEs are shipped and further processed abroad due to lack of domestic processing facilities. Separation of rare earth elements is an essential step towards their reduction to rare earth metals for practical applications. It is an important purification step, the product of which are typically oxides that are further subjected to reduction processes to obtain the desired metal. The need for separation also arises for recycled rare earth products in which they are typically recovered as mixed salts or oxides which, again, requires subsequent reduction to obtain the desired metals for applications, e.g., permanent magnets development. The industrial separations process involves leaching, followed by a selective extraction. The leaching processes require strong oxidizing/harsh chemicals for dissolution of rare earth concentrates or recycled products which pose a significant environmental impact towards disposal of acidic waste effluents. Also, operating conditions for the different separation processes vary depending on feedstock type, making them economically taxing. For metal production, the commercial methods involve metallothermic and electrolytic reduction of REE salts and oxides. For example, calciothermic methods require REE halides or oxides, followed by thermic reduction using Ca in an inert atmosphere. The need for high-temperature results in an energy-intensive process; fluorination is operationally risky due to the typical need for HF and hydrogen evolution. Moreover, achieving high purity and high yield in the process appear to be mutually exclusive. All these make the process costly. Although NdCl3 has been proposed as a substitute for NdF3, it is limited by high hygroscopicity, hence low yield and high impurities. Also, molten salt electrolytic reduction processes have poor yield and scalability. Moreover, the logistics of both REE separation and metal reduction being performed by different companies with different business focuses and technological capabilities, result in increased costs which subsequently impacts the price of the final product. This is exacerbated by the current state-of-the-art separation and reduction processes being energy intensive, environmentally taxing, requiring substantial amounts of hazardous chemicals and producing significant amounts of solid and liquid wastes. There is a need for an improved method to obtain one or more REMs from compounds, complexes, etc., containing one or more REEs. This need is better addressed if metal reduction is a means for separation. SUMMARY OF THE INVENTION Certain embodiments of the present invention provide a rare earth laser-assisted metal production and separation (RELAMPS) technology by photochemical selective reduction of various REE-containing compounds and complexes as well as others using a pulsed laser wherein such other compounds and complexes include, but are not limited to La, Ce, Pr, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Certain embodiments of the present invention employ a pulsed laser to implement the selective reduction (separation) process at room temperature. The pulsed laser light is impinged and controlled to selectively dissociate molecular bonds in REE oxides, oxalates, halides and other compounds and complexes. Practice of embodiments of the present invention is advantageous in that an infinitesimally small time-period for bond cleaving and energy transport using a picosecond and femtosecond laser prevents loss of energy makes practice of method embodiments very efficient. Consequently, instead of the typically required high temperatures (>800° C.) heretofore employed, practice of method embodiments can achieve separation of REE-containing compounds and complexes by reduction to REMs (rare earth metals) at ambient temperature conditions and excludes the use of harsh chemicals. Moreover, the versatility of laser irradiation of a REE-containing