Iowa State University Research Foundation Inc.

The United States of America as Represented by the United States

David T Peterson

Frederick A Schmidt

John T Wheelock

Lawrence L Jones

Lanny P Lincoln

Rare earth-transition metal (e.g., iron) scrap (e.g., Nd-Fe-B scrap) is flux (slag) remelted to reduce tramp non-metallic impurities, such as oxygen and nitrogen, and metallic impurities, such as Li, Na, Al, etc., picked up by the scrap from previous fabrication operations. The tramp impurities are reduced to concentrations acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets. The scrap is electroslag or inductoslag melted using a prefused, rare earth fluoride-bearing flux of CaF.sub.2, CaCl.sub.2 or mixtures thereof or the slag resulting from practice of the thermite reduction process to make a rare earth-iron alloy.

Method for treating rare earth-transition metal scrap

Rare earth-transition metal (e.g. iron) scrap (e.g. Nd-Fe-B scrap) is melted to reduce the levels of tramp oxygen and nitrogen impurities therein. The tramp impurities are reduced in the melt by virtue of the reaction of the tramp impurities and the rare earth to form dross on the melt. The purified melt is separated from the dross for reuse. The oxygen and nitrogen of the melt are reduced to levels acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets.

Rare earth-transition metal scrap treatment method

A particulate mixture of Fe.sub.2 O.sub.3 and RE.sub.2 O.sub.3, where RE is a rare earth element, is reacted with an excess of HF acid to form an insoluble fluoride compound (salt) comprising REF.sub.3 and FeF.sub.3 present in solid solution in the REF.sub.3 crystal lattice. The REF.sub.3 /FeF.sub.3 compound is dried to render it usable as a reactant in the thermite reduction process as well as other processes which require an REF.sub.3 /FeF.sub.3 mixture. The dried REF.sub.3 /FeF.sub.3 compound comprises about 5 weight % to about 40 weight % of FeF.sub.3 and the balance REF.sub.3 to this end.

Rare earth/iron fluoride and methods for making and using same

An improved method for the preparation of high-purity rare earth-iron alloys by the aluminothermic reduction of a mixture of rare earth and iron fluorides.

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Ames, IA, United States of America

David T Peterson