Document Type

Honors Thesis

Publication Date

Summer 8-7-2026

Abstract

Samarium cobalt (SmCo) based magnets are among the strongest permanent magnets second only to neodymium iron boron (NdFeB) based magnets. While SmCo-based magnets have lower remanence and coercivity than NdFeB-based magnets at room temperature, SmCo-based magnets retain these properties better at higher temperatures. As a result, SmCo-based magnets find use in a variety of devices operating at elevated temperatures including traveling wave tubes for satellite communications, electrical generators, and control surface actuators for aviation system. With increasing geopolitical tension over the sourcing of Sm and Co, there is a renewed interest in recycling end-of-life SmCo-based magnets. This work explores a new recycling process for recovering Sm, Co, and other elements from SmCo-based magnets.

In this process, SmCo-based magnets are selectively oxidized by heating in a controlled atmosphere. The more reactive elements in the magnets like Sm and Fe are oxidized while the less reactive elements like Co and Cu remain as metal. Electrorefining is then used to recover Co and Cu from the selectively oxidized magnets, leaving the oxides, primarily SmFeO3 and Sm2O3, behind. Sm2O3 is recovered from SmFeO3 by selectively reducing the SmFeO3 with C which produces a mixture of Sm2O3 and Fe. This Sm2O3 may then be converted to Sm metal using a suitable reducing agent.

The first chapter of this work investigates the kinetics and microstructure evolution in SmCo-based magnets undergoing selective oxidation. The second chapter examines the selective carbothermic reduction of SmFeO3 and factors influencing separation of the resulting Sm2O3/Fe mixture. The final chapter explores Si as a novel reducing agent for producing Sm metal from Sm2O3. These investigations evaluated the viability of the individual steps and determined factors key to the success of the overall recycling process.

Together the reactions investigated in this dissertation make up an innovative and sustainable process for recycling end-of-life SmCo magnets. Such processes are crucial to ensure continued access to Sm, Co, and other critical materials.

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