Abstract: Ion-adsorption rare earth ore is a critical strategic resource,yet its dominant ammonium salt precipitation process causes serious ammonia-nitrogen pollution.To achieve green and efficient recovery,this study investigated the use of magnesium oxide as a novel precipitant for the recovery of yttrium,a representative rare earth element,and explored the under lying mechanism.Through systematic experiments,the optimal conditions were determined as follows:magnesium oxide added in slurry form with a dosage ratio of 2.4,a precipitation temperature of 90 ℃,and a reaction time of 4 h.Under these condi tions,a high-quality yttrium hydroxide product was obtained with a precipitation rate of 98.57% and a purity of 79.55%.Char acterization by XRD,SEM,and TG-DTG revealed that the precipitate was amorphous yttrium hydroxide with a rough surface and irregular particles.After calcination at 900 ℃ for 2 h,the precipitate transformed into well-crystallized,high-purity Y2 O3 with a smooth surface and uniform morphology.This research confirms that magnesium oxide as a precipitant can fundamentally eliminate ammonia-nitrogen pollution,providing a solid theoretical foundation and technical support for the green extraction of ion-adsorption rare earth ores and the advancement of in-situ leaching technology.

Key words: 　ion-adsorption rare earth ore,magnesium oxide,precipitation recovery,yttrium,mechanism analysis