This project focuses on the study and analysis of the permanent magnet from waste electronic and electrical equipment, and the development of rare-earth recovery technology for permanent magnet. First, the permanent magnet was demagnetized by heating at 400°C for 30 minutes, and crushed into 100 mesh powder. The analysis results of powder composition show that actuator from hard disk and rotor from air conditioner compressor motor are made of neodymium-iron-boron rare-earth permanent magnets. The recovery rate and purity of rare-earth oxide by using rare-earth-sodium sulfate complex salt method is 90.5% and 90.4%, respectively. In order to create better purity, hydrochloric acid leaching with previous iron oxidation method was used in this study. After roasting at 800℃, which is the best temperature according to our study, rare-earth permanent magnet was dissolved in a hydrochloric acid with solid to liquid ratio of 1:4 ~ 1:20 at 60℃. Next, pH value of the solution was adjusted to 3.5 by adding sodium hydroxide, and be heated at 50℃ for 30 minutes. After that, the iron hydroxide in acid solution precipitated, and impurities were also removed. With the addition of anhydrous oxalic acid with solid to liquid ratio of 1:100 controlling at 40°C, rare-earth oxalate was able to be precipitated. By calcining the rare-earth oxalate at 850°C to decompose CO2, it can be formed into rare-earth oxide. The recovery rate of rare-earth by this method is 85.5%, along with purity of 95.7%. This project has completed the dismantling, demagnetization and pre-treatment of permanent magnet from waste electronic and electrical equipment, and completed the procedures of roasting oxidation to form insoluble iron oxide, leaching in hydrochloric acid, precipitation and calcination of oxalic acid, and successfully recovered rare-earth Oxides.

waste electrical and electronic equipment, rare earth recovery, nebidium oxide