超重力强化金属铋提取废旧钕铁硼中稀土元素

钕铁硼是应用最广泛的永磁材料，每年会产生大量达到使用年限的废旧钕铁硼。这些废料中含有20%~30%稀土元素，是宝贵的二次资源。文中以金属铋为提取剂，通过火法熔炼回收废旧钕铁硼中的稀土元素，并利用高温超重力技术将过量的铋分离，用于循环使用。考察了熔炼过程中铋废质量比对稀土提取效率的影响，以及超重力离心过程中温度和重力系数对铋的回收率的影响。结果表明，在铋废质量比大于1∶1时，铋相与铁相分层效果较好，废旧钕铁硼中的稀土元素几乎全部进入铋相中；在较优分离条件:T=500 ℃、G=1 000下，稀土回收率达99.8%，铋的回收率达72.7%。该工艺的成功开发为废旧钕铁硼中稀土元素回收利用开辟了一条新途径。 

Extraction of rare earth elements from spent NdFeB magnets by supergravity-enhanced bismuth

Since NdFeB is the most widely used permanent magnet material, a large amount of spent NdFeB magnets will reach its service life every year. These wastes contain 20%~30% rare earth elements, which are valuable secondary resources. In this paper, bismuth(Bi) metal was used as extractant to recover the rare earth elements in spent NdFeB magnets by fire melting, to seperate the excess Bi by high-temperature supergravity technology, for recycling. The influence of Bi waste mass ratio on rare earth extraction efficiency in melting process, and the impact of temperature and gravity coefficient on Bi recovery rate in supergravity centrifugation process were investigated. The results show that when Bi waste mass ratio is over 1:1, the separation of Bi phase from iron phase is good, and almost all rare earth elements in spent NdFeB magnets entered Bi phase. At a better separation condition, i.e., T=500 ℃ and G=1 000, the recovery rate of rare earth elements reaches 99.6% and that of Bi 74.7%. The successful development of this process has opened up a new way for recycling rare earth elements in spent NdFeB magnets.