Developments and Perspectives of Recycling Techniques for Rare-Earth Polishing Powder Waste

Clean and efficient recycling of rare-earth polishing powder waste (REPPPW), which is a rare earth solid waste with great recycling value due to its high rare-earth content (> 40 wt.%), is important for not only environmental protection but also for the alleviation of stringent quotas of rare-earth native resources. In this paper, the origin and properties of REPPW are briefly introduced. The current recycling techniques are categorized into four kinds, i.e., beneficiation method, impurity chemical removal method, pyro-hydrometallurgical combined method, and acidic separation method, the fundamentals are analyzed, followed by a critical review of the advantages and limitations. Focusing on the challenges of the acidic separation method, which is the current hotspot in this area, the potential directions for future research are discussed. The aim of this work is to provide insight into the current REPPW recycling technologies and inspire future development of clean, efficient, and value-added REPPW recycling techniques.