Decomposition of Rare Earth Containing Ores by Alkaline Hydrothermal Process

摘要

Xenotime, monazite and ion exchange ores were reacted with NaOH solution in the micro-autoclave under high temperature and pressure to produce a mixture of rare earth hydroxides. The decomposition reaction of phosphate ores such as xenotime and monazite required higher temperature and NaOH concentration than those for the decomposition of carbonatite in. bastnaesite. The recovery of phosphate from the ores was limited by the solubility of Na_2PO_3 in the NaOH solution. The recovery of yittrium was decreased with the increase in the reaction temperature because the equilibrium phase changed from Y(OH)_3 to YOOH above 61 OK, which was determined by the experiment.