Ultrasound and Microwave assisted leaching of neodymium from waste magnet using organic solvent

• Published in: Hydrometallurgy 2019-05, Vol.185, p.61-70
• Main Authors: Behera, S.S., Panda, Subhendu K., Mandal, D., Parhi, P.K.
• Format: Article
• Language: English
• Subjects: CH3COOH; Magnet waste; Microwave; Regular leaching; Ultrasound wave
• ISSN: 0304-386X; 1879-1158
• DOI: 10.1016/j.hydromet.2019.02.003

Application of ultrasound and microwave assisted technology on the dissolution of neodymium (Nd) from waste magnet using organic reagent (s) was investigated. Amongst all the organic solvents, acetic acid appears to be effective while yielding higher Nd leaching efficiency. The characteristics pattern of XRD and SEM-EDAX study ascertained the magnet waste phase as Nd-Fe-B. Factors influencing the leaching of Nd such as time (0-5 h), [CH3COOH] (0.1–0.5 M), ultrasound power (0 W–120 W), pulp density(S/L) (1–5%) and microwave power (450-900 W) have been studied. Quantitative (~99.99%) Nd recovery was achieved under optimum ultrasound assisted leaching condition; time: 120 min, ultrasound power: 90 W, [CH3COOH]: 0.4 M and particle size range: 75–106 μm. Almost all Nd dissolution was attained at the suitable MW power of 900 W leading to reduce leaching time by 120 min than the regular mechanical stirring leaching (65.03% Nd resulted in 240 min). The enhancement of Nd leaching was mainly due to unique cavitation action of ultrasoundation and high heating energy produced from microwave to break the solid matrix of waste magnet, leading to diffuse the Nd metal ion into lixivaint phase as ascertained from SEM results of the magnet waste sample before and after ultrasound wave / microwave treatment. [Display omitted] •Ultrasonic/microwave-assisted leaching study for recovery of Nd from magnet waste.•Leaching study of Nd was carried out by adopting various organic green solvents.•Sonication/microwave found be key on yielding high Nd leaching than regular process.•Nd leaching maximized by dil.CH3COOH at mild ultrasonic power (90 W) with 900watt MW.•Proposed process is an environmental-friendly, low cost and highly efficient approach.