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

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 (450900 W) have been studied. Quantitative (similar to 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 mu m. 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.