高温における Nd2O3–Na2B4O7 擬 2 元系の相関係とネオジム磁石のリサイクルへの応用

Translated title of the contribution: High Temperature Phase Relations of the Nd2O3–Na2B4O7 Pseudo Binary System and Their Application to Recycling of Neodymium Magnets

Hiroki Wada*, Masaya Arai, Kazuhiro Ogawa, Katsunori Yamaguchi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

A high temperature recycling process of neodymium magnets using B2O3 flux has been reported. However, the B2O3 flux shows a poor fluidity of the slag. For this purpose of solving the problem, present work considers the use of Na2B4O7 with lower viscosity than the B2O3 flux. The phase equilibria for the Nd2O3–Na2B4O7 pseudo binary system was investigated in the temperature range from 1460 K to 1780 K. We found that this pseudo–binary system forms the homogeneous melt in the concentration range of from 16 mass%Na2B4O7 to 20 mass%Na2B4O7 and over 55 mass% Na2B4O7 at 1673 K. Based on the determined this diagram, the feasibility study of the recycling process of the neodymium magnets using Na2B4O7 flux was carried out 20 kg and 100 kg high frequency induction furnace. When neodymium magnets and an EV rotor were melted with Na2B4O7 in a carbon crucible, the rare earth elements of Nd, Pr, Dy and Tb in the magnets and rotor were enriched to the Na2B4O7 slag phase and the iron in the magnets and the rotor were contributed to the Fe–C alloy phase. The oxalate precipitation method was used for the recovered Nd2O3–Na2B4O7 slag, more 99mass% purity ratio of RExOy was recovered.

Translated title of the contributionHigh Temperature Phase Relations of the Nd2O3–Na2B4O7 Pseudo Binary System and Their Application to Recycling of Neodymium Magnets
Original languageJapanese
Pages (from-to)359-365
Number of pages7
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume85
Issue number9
DOIs
Publication statusPublished - 2021

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

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