Method for preparing rare earth oxide from rare earth polishing powder waste

The invention relates to a method for preparing rare earth oxide from rare earth polishing powder waste. The method is characterized in that the rare earth polishing powder waste is subjected to alkali roasting and washed acidification for decontaminating and is precipitated, filtered, washed and dried to obtain a rare earth oxide finished product. Acidified filtrate is precipitated and filtered for decontaminating and is burnt to obtain the rare earth oxide finished product. The method has the advantages that acids, such as hydrogen fluoride and nitric acid great harm to the environment are not used, the recycling process is pollution-free, the rare earth polishing powder waste is reasonably utilized comprehensively, the rare earth recovery ratio achieves more than 90%, and the rare earth oxide finished product with the purity of more than 95% can be prepared. Alkali and acid wastewater can be recycled after treatment, the rare earth polishing powder waste is utilized comprehensively, and the entire recovery process is environmentally-friendly and pollution-free.