Rice team unveils “flash Joule + chlorine” one-step route to recycle REE magnets with high purity, low cost

Sep 14, 2025

Highlights

  • Rice University researchers develop a revolutionary one-step process to extract rare earth elements from waste magnets.
  • The process uses ultra-high-temperature flash Joule heating and chlorination.
  • New method cuts energy use by 87%.
  • Reduces greenhouse gas emissions by 84%.
  • Eliminates water and acid usage compared to conventional recycling techniques.
  • Potential to transform rare earth element recycling economics.
  • Simplifies magnet waste processing from multiple steps to a single thermal-reactive step.

Lead author Shichen Xu (Department of Chemistry, Rice University), with senior author James M. Tour, reports a preprint in ChemRxiv (Sept. 2025) introducing flash Joule heating combined with chlorination (FJH-Cl₂) to separate and recover rare earth elements (REEs) from SmCo and NdFeB waste magnets.

Study at a Glance

Xu et al. at Rice University (Departments of Chemistry, Materials Science & NanoEngineering, and Civil & Environmental Engineering) report a ChemRxiv preprint (opens in a new tab) (not peer-reviewed) proposing that brief, ultra-high-temperature flash Joule heating combined with chlorine can leverage Gibbs free-energy and boiling-point differences to volatilize transition-metal chlorides while retaining rare-earth oxychlorides—enabling rapid, selective separation of REEs from magnet waste.

Key Findings

  • Single-step separation: >90% purity and >90% yield for Sm (SmCo) and ≥94% purity with >93% REE recovery for Nd/Pr/Ce residues (NdFeB).
  • Process intensity: Seconds-long reaction at ~1,180–1,910 °C using a commercial arc welder; temperature tightly tunable.
  • LCA/TEA (Sm case): vs. conventional hydrometallurgy, FJH-Cl₂ cuts energy ~87%, GHG ~84%, opex ~54% (up to 69% when remote mining logistics included), and eliminates water and acid use.
  • By-products: CoCl₂ and FeCl₃ streams offer potential value for batteries and water treatment.

Why It Matters for the REE Supply Chain

If validated at scale, FJH-Cl₂ could shrink magnet-recycling flowsheets from dozens of unit ops to one thermal-reactive step, lowering capex/opex and domesticating a critical part of REE supply. Faster, cleaner magnet waste valorization would buffer Nd/Pr/Sm availability, diversify away from single-country refining chokepoints, and create circular feedstock for permanent-magnet manufacturers serving EVs, wind, and defense.

Limitations & What to Watch

  • Preprint status: Findings are not yet peer-reviewed; external replication is essential.
  • Feedstock breadth: Demonstrated on SmCo and NdFeB lab powders; performance across mixed, coated, or oxidized scrap streams (incl. heavy REE-bearing alloys, Dy/Tb) remains to be tested.
  • Scale-up engineering: Thermal uniformity, chlorine handling/recovery, off-gas treatment, and materials compatibility at industrial throughputs must be proven.
  • Economics: TEA/LCA rely on Class-4 estimates with ±30% Monte-Carlo bounds; site-specific energy pricing, chlorine recycle rates, and emissions permitting will move the needle.
  • Product upgrading: Residual REE oxychlorides still require conversion/purification to marketable oxides/metals; downstream quality specs (magnet-grade) must be met.

Conclusion

Xu et al. present a compelling process-intensified route for REE magnet recycling that checks the boxes investors and policymakers care about: speed, selectivity, footprint, and cost. The industrial proof will hinge on third-party replication, safe chlorine-loop design, and steady-state operations at kg→ton scale—yet the early data position FJH-Cl₂ as a credible contender to rewrite Western REE recycling economics.

Citation: Xu S, Sharp J, Deng B, Liu Q, Eddy L, Chen WQ, et al.; Tour JM (corresponding). Sustainable Separation of Rare Earth Elements from Wastes (opens in a new tab). ChemRxiv (preprint), 2025. doi: 10.26434/chemrxiv-2025-pqkj3. (Content not peer-reviewed.)

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By Daniel

Inspired to launch Rare Earth Exchanges in part due to his lifelong passion for geology and mineralogy, and patriotism, to ensure America and free market economies develop their own rare earth and critical mineral supply chains.

1 Comment

  1. Scott

    ReElement (AREC owns 19%) utilizes ligand displacement chromatography to separate & purify REE.
    No chemical solvents needed.
    Just need some resin coated columns & the patented intellectual property in order to do so.

    “ReElement Technologies Produces Greater than 99.9% Pure Separated Germanium
    Successfully achieves high-purity germanium from recycled material and ore-based feedstock through internally developed flow sheet

    Targeting defense and advanced industrial partners requiring 99.9%-99.999% purity, sourced from virgin supply or customer-provided recycled feedstock

    Multi-mineral, multi-feedstock refining platform continues to set global benchmarks for versatility and efficiency”

    ReElement can achieve 99.9% purity from a wide range of feedstocks.
    They currently are producing & are in the process of ramping up production

    Reply

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