摘要
钕铁硼磁体是重要的稀土功能材料。随着新能源汽车、风力发电、电子信息等行业的快速发展,对钕铁硼磁性材料的需求量逐年增加。我国是世界上最大的钕铁硼生产国,2018年产量达17万t,占世界总产量近90%。钕铁硼在生产过程中会产生约30%的废料。此外,每年也会产生大量因达到使用年限而报废的磁体。这些废料中含有20%~30%的稀土元素,是宝贵的二次资源,对其进行循环再利用,不仅有利于环境保护,同时也有助于促进稀土产业的可持续发展。不同来源的废料成分特点差别较大,因而采用的处理方法也有所差别。目前的研究方向主要有两个:(1)从废料中回收稀土元素;(2)利用废料进行磁体再生制造。其中稀土回收方法主要包括湿法和火法两大类。如何实现稀土再生产品质量与环境友好度、经济性的有机统一,是钕铁硼废料循环利用领域的热点与难点。湿法回收工艺包括盐酸全溶法、盐酸优溶法、硫酸复盐沉淀法等,其共性特点为通过控制p H值,将稀土与其他元素分离;通过多级萃取得到单一稀土化合物,之后采用沉淀剂将稀土转化为盐类,经焙烧后得到单一稀土氧化物。此类方法对原料适应性强,稀土产品纯度高,但流程长、对环境不友好。火法回收工艺包括氧化法、氯化法、液态合金提取法等,其原理是基于稀土元素、其他元素与氧、氯、合金元素结合能力的差异性。此类方法流程短、对环境相对友好,但通常得到的是混合稀土化合物,产品纯度较低,且尚未实现工业化。近年来,国内外发展了诸多回收新方法,如电化学法、离子液体法、水解法等,但均处于起步阶段。其中通过电解法、水解法得到混合稀土化合物,离子液体法具有分离效率好、体系稳定性高等优点,具有一定发展前景。短流程再生制造主要包括氢爆法、掺杂法、热压法等,此类方法流程短、对环境友好,但再生磁体磁能积往往会有一定程度降低,从而限制其进一步应用。如何保证再生磁体的磁性能是未来再生制造发展的重点。本文首先对钕铁硼废料产生的途径及成分特点进行简要介绍,然后综述了各种循环处理方法(湿法、火法、回收新方法、短流程再生制造)的研究现状及问题,并对未来的发展趋势进行了展望,以期为钕铁硼废料的综合利用提供一定参考。
Nd Fe B magnet is one of the important rare earth functional materials.With the rapid development of new energy vehicles,wind power generation,electronic equipment and other industries,the demand for Nd Fe B magnets has been increased year by year.China is the largest producer of Nd Fe B in the world.The annual output is nearly 170000 t,accounting for nearly 90%of world production.About 30%waste is produced during production process.In addition,a large number of magnets are discarded when the service life is reached.These wastes contain 20%—30%rare earth elements,which are valuable secondary resources.Waste recycling is not only conducive to environmental protection,but also contributes to the sustainable development of the rare earth industry.The composition characteristics of various Nd Fe B waste are quite different.Therefore,the treatment methods are also different.There are two research directions:(Ⅰ)recovery of rare earth elements from Nd Fe B waste;(Ⅱ)magnet regeneration manufacturing.The recovery method consists of hydrometallurgy and prometallurgy.How to achieve the organic unity of rare earth regeneration product quality,environmental friendliness and economy has become the hotspot and difficulty.The hydrometallurgy technologies include hydrochloric acid total solution method,hydrochloric acid optimal solution method,sulfate double salt precipitation method,etc.The general characteristics of these technologies are list as follows:the rare earth is separated from other elements by controlling the p H value.Single rare earth compound is obtained by multistage extraction.Then,the rare earth is converted into salt by precipitator,and the single rare earth oxide is obtained after calcination.These methods are highly adaptable to different raw materials,the purity of rare earth products is high.However,the process is long and environmentally unfriendly.The prometallurgy technologies include oxidation method,chlorinate method,liquid alloy extraction method,etc.The principle is based on the ability of rare earth elements and other elements to combine with oxygen,chlorine and alloying elements.These methods are short-process and relatively environmentally friendly,but mixed rare earth compounds are usually obtained.In addition,these methods are not industrialized.In recent years,new recovery methods have been developed at home and abroad,such as electrolysis method,ionic liquid method,hydrolysis method,etc.,but they are still in their infancy.Mixed rare earth compound are obtained by electrolysis and hydrolysis method.Ionic liquid method has the advantages of good separation efficiency and high system stability,showing good prospect.Short-process regenerative manufacturing methods mainly include hydrogen detonation method,doping method,etc.These methods are short-process and relatively environmentally friendly.However,magnetic property usually decrease to a certain extent,which will further limit its application.How to ensure the property of regenerative magnets is the key point of regenerative manufacturing development in the future.This article briefly introduces the sources and characteristics of Nd Fe B waste,then summarizes the research status and problems of various recovery methods(hydrometallurgy,pyrometallurgy,new recycling methods,short-process regeneration manufacturing).The research development tendency is also prospected.The article is expected to provide a reference for the comprehensive utilization of Nd Fe B waste.
作者
李世健
崔振杰
李文韬
王东
王志
LI Shijian;CUI Zhenjie;LI Wentao;WANG Dong;WANG Zhi(Key Laboratory of Green Process and Engineering,Hydrometallurgy Clean Production Technology National Engineering Laboratory,Institute of Process Engineering,Chinese Academy of Science,Beijing 100190,China;Ganjiang Innovation Academy,Chinese Academy of Science,Ganzhou 341119,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2021年第3期3001-3009,共9页
Materials Reports
基金
国家重点研发计划项目(2020YFC1909004)
北京市自然科学基金(2192055)。
关键词
钕铁硼废料
循环利用
湿法
火法
再生制造
稀土资源
NdFeB waste
cycling utilization
hydrometallurgy
pyrometallurgy
regeneration manufacturing
rare earth resources
