DOE SBIR Phase I Final Technical Report: Ionic Liquids as Advanced Solvents for the Extraction of Rare Earth Elements from Coal Products
The overall goal of this SBIR Phase I project was to demonstrate the feasibility of an ionic liquid (IL) process for the direct extraction of rare earth elements (REEs) from coal and demonstrate the recovery of REEs from the coal-IL solution, in a sustainable and energy efficient manner. Phase I confirmed the feasibility of this approach on both coal and coal by-products, resulting in 92-100% extraction of REEs from coal into IL, resin separation, and recovery of REE solids via developed electrochemical methods. In this Phase I project, we demonstrated the technology and evaluated IL design, REE extraction parameters, and REE recovery methods, which have provided essential chemistry and engineering knowledge needed for our process design and scale-up to a mini-pilot prototype system in Phase II. Below are important Phase I accomplishments: Ionic liquid design. We have successfully demonstrated the extraction of REEs from coal and fly ash into specifically designed ILs in a simple and energy efficient manner. REE extraction and recovery from coal was performed via direct treatment of coal with intelligently designed task-specific ILs. The IL chosen for these processes possesses an ideal combination of excellent solvation ability, nonvolatility, low toxicity, proven recyclability, and availability at the multi-ton scale. Rare earth element extraction. Detailed studies were performed to determine variables which affect dissolution parameters and REE extraction efficiency in order to determine optimal treatment parameters. Parameters which affect dissolution were determined, and an optimal treatment process was developed. We can reproducibly extract 92-100% of REEs from coal into IL in as little as two minutes of treatment. Preliminary studies indicate that our process can also be applied to other sources of coal and ash from different U.S. mines. Rare earth element recovery. REE separation from coal-IL solutions was demonstrated using both commercially available resins and chitin-based sorbents. The resins tested were able to efficiently extract 99% of REEs from solutions of coal-IL and fly ash-IL. It was demonstrated that the REEs could be recovered from the resins into aqueous solutions. An electrochemical method for the recovery of REEs directly from the aqueous eluents from these separation processes has been demonstrated. Major products of this process are the production of individual and mixed REEs. Additional applications include the valorization of co-products from recovered REE-free residues, oil, and solid precipitate. Co-products include valuable metals (e.g., Li, V), carbon materials, and chemicals which will increase the commercialization value of this process. Secondary applications include the use of this process in coal by-product remediation/processing, as this process has been demonstrated with fly ash. We are now ready to scale-up our processes in Phase II from the current 10 mL benchtop scale to a 3 L mini-pilot demonstration unit in order to fine tune the engineering parameters necessary to further design and develop, also during Phase II, a prototype pilot unit (20 L) for a continuous processing system.
- Research Organization:
- Wyonics LLC
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- SC0018561
- OSTI ID:
- 1491460
- Type / Phase:
- SBIR (Phase I)
- Report Number(s):
- DOE-WYONICS-18561
- Country of Publication:
- United States
- Language:
- English
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