Using Chlorine Gas to Recover Rare Earth Metals from End-of-Life Permanent Magnets

We describe a laboratory-scale process for recycling rare earth metals from end-of-life rare-earth/iron/boron alloy permanent magnets using a 2-h chlorine gas treatment at 673 K. This treatment does not require any special preparation of the magnets; they can be used without demagnetization, crushing or milling. Following treatment at 673 K, a clinker powder consisting of rare earth metal chlorides with minimal amounts of other metals is obtained, while hematite and iron oxychloride sublimate. Following literature sources, we suggest that the rare earth metal chlorides in the clinker may be readily reduced to metal, either by electrolysis in relatively low temperature eutectic melts or by metallothermic reduction in mixtures with alkali or alkaline earth metals.

Automated summary

A laboratory-scale process has been developed to recycle rare earth metals from end-of-life rare-earth/iron/boron alloy permanent magnets using a 2-hour chlorine gas treatment at 673 K. The treatment produces a clinker powder consisting of rare earth metal chlorides with minimal amounts of other metals, which can be further reduced to metal through electrolysis or metallothermic reduction.