Industrial & Engineering Chemistry Research, Vol.37, No.6, 2093-2098, 1998
Precipitation stripping of yttrium oxalate powders from yttrium-loaded carboxylate solutions with aqueous oxalic acid solutions
Precipitation stripping is a combined process of the stripping and precipitation stages in a conventional solvent extraction process for separation and purification of rare earths. Crystalline yttrium oxalate powders were precipitated by emulsifying yttrium-loaded carboxylate solutions with aqueous oxalic acid solutions at 30 degrees C and atmospheric pressure. The yttrium in the organic solution was completely stripped and. precipitated within the first 5 min of mixing with the aqueous solution. The particle size distributions of the oxalate powders were markedly dependent on processing parameters, such as mixing time, liquid-phase stirring speed, initial organic-phase concentration of yttrium carboxylate, and ionic strength of the aqueous oxalate solution. In addition, the nature of the two solvent extractants, carboxylic acid and phosphoric acid systems, had little effect on the size distribution of yttrium oxalate.