Selective Recovery of Ce and La from Coal Ash Leachates by Stepwise pH-Controlled Precipitation

Coal ash represents an abundant secondary resource of rare earth elements (REEs), but their recovery is hindered by low concentrations in leachates and the presence of large amounts of competing matrix elements such as Fe, Al, Ca, and Mg. In this study, a stepwise pH-controlled precipitation approach was applied to real sulfuric acid coal ash leachates for selective recovery of Ce and La. The process combined impurity scrubbing, oxidative precipitation of Ce, and phosphate precipitation of La. Nearly complete recovery was achieved, with >95% of both Ce and La recovered and >99% phase purity. Selectivity analysis further demonstrated strong discrimination of REEs over matrix elements, with Ce showing >400 selectivity over Fe, Al, and Ca, and La showing ~170 over the same ions and ~17 over Ce. These results show the efficiency of the approach under realistic multi-element conditions.