Recovery of neodymium, dysprosium, and iron from spent mobile phone camera module magnets through a hydrometallurgical method

Abstract

Neodymium (Nd), dysprosium (Dy), and iron (Fe) were recovered from spent mobile phone camera modules via leaching and a solvent extraction procedure. Nd, Dy, and Fe, together with other minor metal ions in the pretreated spent mobile phone camera modules, were dissolved using an HNO3 solution. The leaching parameters, such as concentration of lixivant, reaction temperature, pulp density, which possibly affect the dissolution efficiency of metal ions, were investigated. From the obtained leachate containing Nd, Dy, Fe, Ni, Co, and B, Nd and Dy, with a small amount of Fe, were extracted using 0.5 mol/L of trioctylphosphine oxide (TOPO). Selective stripping of Nd and Dy from the loaded TOPO was achieved using 3 mol/L hydrochloric acid. After removing Nd and Dy from the leachate, Fe was extracted using 1 mol/L of TOPO followed by stripping with oxalic acid. McCabe-Thiele diagrams for the extraction and stripping of Nd/Dy and Fe were constructed. The results were validated via counter-current simulation experiments using a real leachate solution. Finally, an integrated process for recovery of Nd, Dy, and Fe from the nitric acid leachate of spent mobile phone camera modules was proposed.