Highlights

• Solvent extraction (SX) is the dominant industrial method for separating rare earth elements since the 1960s, known for its efficiency and scalability.
• Digital technologies like AI and advanced spectroscopy are expected to enhance SX processes, potentially reducing costs and improving precision.
• European research centers like SOLVOMET are leading innovations in sustainable hydrometallurgical processes for critical metals extraction.

Solvent extraction (SX) remains the gold standard for separating rare earth elements (REEs), and experts predict it will continue to be so for the foreseeable future. These elements—used in everything from magnets in electric vehicles to lasers and medical devices—are found together in nature and must be separated into pure forms before use. While older methods, such as crystallization and ion exchange, were once used, SX has been the leading industrial method since the 1960s due to its efficiency, scalability, and ability to operate continuously.

The topic was recently covered online via Koen Binnemans, (opens in a new tab) Professor of Metallurgical Chemistry, KU Leuven, Head of SOLVOMET Group. (opens in a new tab)

The reason SX is so dominant is its ability to handle large volumes of rare earth mixtures in huge industrial plants. Some facilities run over 1,000 mixer-settler units to separate all the REEs. While the technology is well-established, there is still room for improvement—not by inventing new chemicals, but by making the process more innovative and more efficient.

That’s where digital tools come in. Researchers expect significant gains in the next few years from AI-powered process control, real-time monitoring, and technologies such as spectroscopy (UV-VIS-NIR and XRF). These upgrades could cut both capital and operating costs while making rare earth separation cleaner and more precise, according to Professor Binnemans.

Europe has deep expertise in this area, led by firms like Solvay (opens in a new tab) and CARESTER (opens in a new tab), and backed by top researchers at KU Leuven’s SOLVOMET center (opens in a new tab). In a world where rare earth supply chains are under pressure, solvent extraction remains a proven, “Lindy-effect” technology—trusted because it’s stood the test of time, and built to keep evolving.

What is the SOLVOMET Group?

SOLVOMET is KU Leuven’s Research and Innovation Centre for Circular Hydrometallurgy. We support mining, metallurgical, and recycling companies in the development of more sustainable (circular, low-energy input) hydrometallurgical processes, utilizing state-of-the-art laboratory and mini-pilot scale experimental facilities and modeling capabilities. SOLVOMET’s vision is that metallurgical chemistry expertise enables the development of more efficient, eco-friendly hydrometallurgical and solvometallurgical processes to provide the critical metals needed for the transition to a climate-neutral society.

SOLVOMET’s mission is to support its industry partners in the conceptual and practical development of more sustainable (circular, low-energy input) hydrometallurgical (and solvometallurgical) processes, which are subsequently tested using state-of-the-art lab-scale and mini-pilot-scale experimental facilities.

Source: SIM² KU Leuven / Journal of Sustainable Metallurgy (2023, 2025) and LinkedIn.