首页|Reaction mechanism of Ca-reduction diffusion process used for sustainable recycling Nd-Fe-B sludge
Reaction mechanism of Ca-reduction diffusion process used for sustainable recycling Nd-Fe-B sludge
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NSTL
Elsevier
? 2022 Elsevier B.V.The reduction diffusion (RD) process for Nd-Fe-B sludge has been reported as a green and efficient method for synthesizing recycled Nd2Fe14B magnetic powders. In this work, recycled Nd-Fe-B powders with low impurity content and uniform particle size distribution were successfully prepared. M3 T increased to 146.25 emu/g, which was about 17% and 32% higher than the purged and original sludge, respectively. Then, the recycled Nd-Fe-B sintered magnets with properties of Br = 12.14 kG, Hcj = 12.00 kOe, and (BH)m = 35.05 MGOe were successfully prepared by doping with 37.70 wt% Nd4Fe14B powders. Based on experimental studies of calcium thermal reduction of Nd-Fe-B sludge and thermo-kinetic analysis, the reaction mechanism of the RD method for sludge waste recovery was clarified. In the RD process, the oxides in the sludge were selectively reduced by Ca at 600–950 °C and the reduced Nd diffused to the surface of the Fe core, forming the Nd-Fe-B alloy, where the formation process included the nucleation stage, the alloy layer high-speed growth stage, and the completion stage. And the relationship between the alloy layer thickness and time during the high-speed growth period of 1–3 h was more in line with linear law (d = 5.41 t–4.31). The RD reaction conformed to the unreacted shrinking core model, and its reaction rate control step consisted of a one-way diffusion process for the diffusion of Nd into the Fe core.
Reaction mechanismRecycling Nd-Fe-B magnetic sludgeReduction diffusionThermodynamics
Xu H.、Lu Q.、Li Y.、Liu W.、Yue M.、Yi X.、Wang Y.
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Beijing University of Technology Key Lab of Advanced Functional Materials
State Key Laboratory of Rare Earth Permanent Magnetic Materials
NSTL
Elsevier
