Nd-Fe-B: From sludge waste to powders via purification and modified Ca-reduction reaction process
Nd-Fe-B: From sludge waste to powders via purification and modified Ca-reduction reaction process
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DOI：
10.1016/j.jmmm.2021.168606
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发表时间：
2022-02
影响因子：
2.7
通讯作者：
Xu Haibo;Wang Feng;Q. Lu;Qiu Yubing;Weiqiang Liu;Jingwu Chen;X. Yi;M. Yue
中科院分区：
文献类型：
--
作者：
Xu Haibo;Wang Feng;Q. Lu;Qiu Yubing;Weiqiang Liu;Jingwu Chen;X. Yi;M. Yue
采用提纯与改进的Ca还原反应相结合的方法，将油基Nd-Fe-B废渣直接回收利用，制备单相Nd 2Fe 14 B粉末。净化后的钕铁硼B污泥废料中杂质和有机物大大减少，减少了后续还原扩散（RD）过程中的钙消耗，从而降低了成本。通过进一步优化Ca还原扩散参数，特别是CaCl 2与KCl的质量比，使液态CaCl 2与气态KCl沿着为充分均匀的Ca还原反应提供条件，成功制备了分散性好、粒度均匀、取向性好的高性能Nd-Fe-B磁粉。采用质量比为1：1的CaCl 2和KCl混合扩散介质，在3 T磁场下，回收的Nd-Fe-B粉末的室温磁化强度提高到157 emu/g，比原始污泥的磁化强度提高了约28%.回收的磁性粉末中的碳、氢和氧的含量分别从6.8、1.8和5.9重量%显著降低到0.1、0.19和0.56重量%。此外，晶粒尺寸均匀（X50= 3.6 μm）且分布良好，极大地改善了取向性，有利于粘结或烧结Nd-Fe-B基磁体的制备。CaCl 2-KCl混合扩散介质能够导致分散良好、均匀的具有高磁化强度的回收粉末的原因是改善液相反应环境和气态KCl防止团聚和抑制颗粒合并或生长的因素的组合。
The oil-based Nd-Fe-B sludge waste was directly recycled to single-phase Nd2Fe14B powders via the combination of purification and modified Ca-reduction reaction method. The impurities and organics in the purified Nd-Fe-B sludge waste were greatly reduced, reducing calcium consumption in the subsequent reduction and diffusion (RD) process, thereby reducing the cost. By further optimizing the Ca-reduction diffusion parameters, especially the mass ratio of CaCl2and KCl, where the liquid CaCl2, along with the gaseous KCl provide conditions for sufficient and uniform Ca-reduction reaction, high-property Nd-Fe-B magnetic powders with good dispersion, uniform particle sizes, and excellent orientation, were successfully obtained. Using the mixed diffusion medium of CaCl2and KCl with a mass ratio of 1:1, the room-temperature magnetization of the recycled Nd-Fe-B powders was increased to 157 emu/g at 3 T-magnetic field, which was about 28 % higher than that of the original sludge. The contents of carbon, hydrogen, and oxygen in the recycled magnetic powders were significantly reduced from 6.8, 1.8, and 5.9 wt% to 0.1, 0.19, and 0.56 wt%, respectively. In addition, the uniform grain size with X50= 3.6 μm and good distribution greatly improved the orientation, which can be beneficial to the preparation of the bonded or sintered Nd-Fe-B-based magnets. The reasons that CaCl2-KCl mixed diffusion medium can lead to well-dispersed, uniform recycled powder with high magnetization arise from a combination of factors for improving the liquid phase reaction environment and the gaseous KCl to prevent agglomeration and inhibit particles merging or growth.