Highlights

• Malaysian researchers modeled a four-train solvent extraction process to separate praseodymium and neodymium to 99.99% purity from ion-adsorbed clay.
• The process reveals that Pr/Nd separation alone requires 62 equilibrium stages and dominates plant footprint and capital costs.
• The study explains why China controls downstream rare earth markets: the chemically adjacent Pr and Nd have a low separation factor (β ≈ 1.70), requiring massive, capital-intensive facilities that most non-Chinese producers cannot economically replicate.
• High-purity Pr and Nd are essential for NdFeB permanent magnets in electric vehicles, wind turbines, and defense systems.
• This simulation-based design demonstrates that any ex-China rare earth strategy must accept either large-scale infrastructure investment or continued supply dependence.

---

A Malaysian research team led by Norazihan Zulkifli of Universiti Malaysia Kelantan (opens in a new tab), working with collaborators from Universiti Sains Malaysia and Universiti Islam Antarabangsa Malaysia (opens in a new tab), has published a detailed engineering study that confronts one of the most difficult bottlenecks in the rare earth supply chain: separating praseodymium (Pr) from neodymium (Nd) to ultra-high purity. Published in Kompleksnoe Ispolzovanie Mineralnogo Syra = Complex Use of Mineral Resources (Vol. 342, No. 3), the paper presents a four-train, counter-current solvent extraction (SX) flowsheet designed to achieve 4N (99.99%) purity Pr and Nd from ion-adsorbed clay (IAC)–derived chloride liquor sourced from Malaysia’s Jeli deposit. The central conclusion is blunt and instructive: Pr/Nd separation dominates plant footprint, capital intensity, and technical complexity, helping explain why China—having mastered this step at scale—continues to control downstream rare earth markets.

Study Design and Methods

Rather than lab experimentation, the authors used steady-state mass-balance simulations—implemented in Microsoft Excel, a standard tool in hydrometallurgical design—to model an industrial SX circuit. The simulated feed was a pre-treated REE chloride solution, and the extractant was P507, a commercially established phosphonic acid reagent.

The proposed flowsheet is organized into four sequential SX trains:

1. a bulk light/heavy rare earth (LREE/HREE) split, (2–3) intermediate fractionation stages, and
2. The final Pr/Nd separation circuit.

Key design variables included A/B cut points between elements and organic-to-aqueous (O/A) ratios across each cascade.

Key Findings

The simulations identify Pr/Nd separation as the dominant bottleneck. Because the two elements are chemically adjacent, the separation factor (β ≈ 1.70) is low, requiring approximately 62 equilibrium stages to reach 4N purity. By contrast, earlier bulk separations require as few as ~16 stages. The study confirms theoretical minimum stage counts (Nmin) and provides stage-by-stage concentration profiles, offering designers a rare level of practical detail.

Bottom line: the Pr/Nd circuit dictates plant size and cost. This is the dividing line between ore production and magnet-grade materials—and the true source of China’s competitive edge.

Why this Matters Beyond Malaysia

High-purity Pr and Nd are critical inputs for NdFeB permanent magnets, which underpin electric vehicles, wind turbines, robotics, and defense systems. The study shows that non-Chinese resources can be processed to commercial purity, but only through large, highly engineered, and capital-intensive SX plants. This reality explains why many countries with upstream resources remain dependent on China for refined outputs.

Limitations & Open Questions

This is a simulation-based design study, not a pilot-plant demonstration. It assumes stable feed chemistry and idealized stage efficiencies, and it does not fully quantify operating costs, reagent losses, waste management, or environmental permitting challenges. IAC resources also raise well-known sustainability concerns. Still, the methodology reflects real industry practice, and the conclusions are technically credible.

REEx Takeaway

This paper does not promise a shortcut. It explains why no shortcut exists. China’s advantage lies not in geology but in process engineering at scale, particularly for Pr/Nd separation. Any serious ex-China strategy must plan for dozens of stages, large footprints, and significant capital—or accept continued dependence.

Citation: Zulkifli, N., Shoparwe, N., Yusoff, A.H., Abdullah, A.Z., & Ahmad, M.N. (2026). Flowsheet Design and Modelling for High Purity Praseodymium and Neodymium by Solvent Extraction. Complex Use of Mineral Resources, 342(3), 111–122. https://doi.org/10.31643/2027/6445.35 (opens in a new tab)