Selective recovery of neodymium from NdFeB wastes by chlorinated roasting and citric acid leaching

Abstract

In this research, the rare earth elements in NdFeB wastes were recovered by combining chlorinated roasting and citric acid leaching. The NdFeB waste was first leached, and the maximum leaching efficiency of Nd reached up to 65.46 % under the conditions with citric acid concentration of 1.0 mol/L, leaching temperature of 90 °C, leaching time of 5 h, and liquid–solid ratio of 50/1 (ml/g). After that the waste was subjected to chlorinated roasting. Ammonium chloride was used as the chlorination reagent with the addition of ammonium chloride at a mass ratio of 3:1, the roasting temperature of 400 °C, and the roasting time of 2 h. The leaching efficiency of Nd after chlorinated roasting was increased to 94.2 % by using citric acid leaching. Nd was finally recovered by oxalic acid precipitation, and the obtained rare earth oxalate was roasted to obtain a rare earth oxide product with a purity of 93.51 %.