Phase equilibrium of the system Ag-Fe-Nd, and Nd extraction from magnet scraps using molten silver

O. Takeda, T. H. Okabe, Y. Umetsu

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

To develop a new recycling process, we examined the direct extraction of neodymium (Nd) metal from Nd-Fe-B magnet scraps using molten silver (Ag) as an extraction medium. Prior to the extraction experiment, the phase equilibrium of the system Ag-Fe-Nd was investigated to estimate the theoretical extraction limit. It was observed that the Fe/Nd2Fe17 mixture equilibrates with the molten Ag-Nd alloy containing 50-52mol% Nd (57-59mass% Nd) at 1363K. The experimental results were in good agreement with the thermodynamic calculation based on literature values. By reacting Nd-Fe-B magnet scraps with molten silver at 1273K, more than 90% of the neodymium in the scrap was extracted, and an Ag-Nd alloy containing 40-50mass% Nd was obtained. The neodymium in the Ag-Nd alloy was separated from silver as Nd2O 3 by oxidizing the obtained alloy in air. Although the wettability of Nd2O3 with molten silver caused some difficulties in the separation of neodymium from silver, molten silver is shown to be an effective medium for neodymium extraction from magnet scrap.

Original languageEnglish
Pages (from-to)305-313
Number of pages9
JournalJournal of Alloys and Compounds
Volume379
Issue number1-2
DOIs
Publication statusPublished - 2004 Oct 6

Keywords

  • Neodymium
  • Phase equilibrium
  • Rare earth magnet scrap
  • Recycling
  • Silver

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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