-
oa Effectiveness Evaluation of Pyrometallurgy and Hydrometallurgy Methods in The Recycling Process of Neodymium-Iron-Boron Permanent Magnet and Rare Earth Metals Recovery: A Review
Circular economy of critical raw materials
- Source: Johnson Matthey Technology Review, Volume 69, Issue 2, Apr 2025, p. 214 - 232
-
- 01 Feb 2024
- 10 May 2024
Abstract
Neodymium-iron-boron is a rare earth element (REE)-based permanent magnet material. Its main magnetic phase is Nd2Fe14B and it has minor phase neodymium-rich or α-iron. The neodymium-iron-boron permanent magnet has a remarkable maximum energy product ((BH)Max) reaching 474 kJ m−3 or nearly 60 mega-gauss-oersteds (MGOe), making neodymium-iron-boron magnets highly suitable for wide use in various technological applications. A commercial neodymium-iron-boron magnet contains 22–32 wt% of REEs such as neodymium, dysprosium, praseodymium and lanthanum. As a result of increasing demand for these materials, the availability of REE from natural resources are decreasing and several REEs such as neodymium, dysprosium and praseodymium are in the critical category. Recycling neodymium-iron-boron magnet waste to recover the REEs is one possible solution to provide raw materials for the permanent magnet industry while minimising electronic device waste. Pyrometallurgical and hydrometallurgical metal extraction processes are commonly used for REE recovery. These two methods are excellent for REE recovery and relatively easy to conduct, allowing pyrometallurgical and hydrometallurgical methods to be adopted on industrial scale to benefit the availability of raw materials for the neodymium-iron-boron magnet industry.