Review Of Rare-Earths Recovery From Polishing Powder Waste

The demand for rare-earth polishing powder is growing the polishing industry owe to the escalating market demand for electronic products, such as touch-screen mobile phones and liquid-crystal display devices. Unfortunately, after service, large amounts of rare-earth polishing powder waste (REPPW) are generated and continuously discarded. However, the REPPW is a promising rare-earths resource due to it contains 40-90 wt.% of rare-earth oxides. In addition, China dominates the global rare-earths market by supplying more than 90% of the global rare-earth element output. However, with China's export quotas becoming increasingly rigorous, most countries will be confronted with uncertainties in rare-earths supply. Thus, recovery of rare-earths from secondary resources such as the REPPW, has become a hot spot in global research, because it is considered an effective pathway to lighten rare-earths market fluctuations and protect the domestic rare-earths resource. Herein, this review comprehensively explores strategies for recycling the REPPW to recover rare-earths. The challenges, advantages, and disadvantages of the proposed technologies and processes, as well as the process optimization for rare-earths recovery from the REPPW are systematically analyzed. The goal of this review is to inspire future research on the REPPW recycling for realizing processes that enable the clean and commercial recovery of rare-earths.