Precipitation of Rare Earth Phosphates from Molten Salts: Particle Size Distribution Analysis

Abstract

Particle size distribution of phosphates of 13 rare earth elements formed in NaCl–2CsCl eutectic based melts at 650 oC was determined. Sodium orthophosphate was used as a precipitant. Initial phosphate-to-rare earth molar ratio in the reaction mixture corresponded to 50 and 100 % degree of precipitation. Particles in the powders obtained after aqueous treatment of quenched melts tend to agglomerate and ultrasonic treatment was employed in the particle size measurements. Normally particles of the phosphates have a size of 0.1–100 μm. The position of the maxima in PSD curves depends on the nature of RE element. In addition, precipitation of mixtures of RE elements mimicking their content in spent nuclear fuels was investigated in NaCl–2CsCl (at 650 oC) and NaCl–KCl (at 750 oC) melts.