カルボニル化反応を用いた希土類磁石スクラップからの新規な資源回収プロセスと電波吸収体としての再生(<特集>希土類系物質の精密合成,形態制御および機能物性)

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Iron element was extracted from the rare earth magnets (Nd-Fe-B and Sm-Fe-N type ones) scrap by the carbonylation reaction with a small amount of sulfur as a catalyst. Both scrap hardly reacted with carbon monoxide, and conversion to iron carbonyl complex was about 30-70% evaluated by energy dispersion X-ray analysis. After the disproportionation of their primary intermetallic phase by hydrogenation or thermal decomposition, the extraction rate for Fe element was significantly accelerated to produce Fe(CO)_5 with the higher yield (〜92%) since the high reactive Fe particles against carbonylation was precipitated as the iron-based nanocomposites by the above treatments. Additionally, the simultaneous extraction of Fe(CO)_5 and decomposition of it with naphthalene in the autoclave vessel was carried out, resulting in the formation of Fe_3C/carbon nanowire composites. The resin compact including the resultant Fe_3C/carbon nanowire composites showed the good electromagnetic wave absorption ability in a GHz range.
2007-10-01