Preparation of Nd(III) Carbonate by Precipitation Stripping of Nd(III)-Loaded VA10

The preparation of fine particles of Nd(III) carbonate from kerosene solution, from which Nd(III) was extracted with versatic acid 10 (VA10) by a precipitation stripping technique using an aqueous NH3-(NH4) 2CO3 solution as stripping medium, was studied. In preliminary experiments, we were unable to recover simple Nd(III) c arbonate from Nd(III)-loaded VA10 by CO2 gas bubbling, when water, (NH4)2CO3, NH4HCO3, NaHCO3, or Na2CO3 solution saturated with CO2 was used as the stripping solution. To obtain simple Nd(III) carbonate, it is necessary to use more than the stoichiometric amount of NH3 compared to VA10 and about 10 times as much (NH4)2CO3 as Nd(III). The solution mixture of NH3-(NH4) 2CO3 acts as a pH buffer, an adductor for VA10, and a CO ion source. Although it was concluded that the precipitates are Nd2(CO3)3·xH2O (x =4), their X-ray pattern does not coincide with that quoted by JCPDS. By heating these precipitates, cubic Nd2O3 was obtained at 823 K, while, at 973 K, hexagonal Nd2O3 was formed. Since the stripping solution consisting of NH3-(NH4)2CO3 was highly alkaline, VA10 was also stripped in the aqueous phase. To use a closed-circuit system for the precipitation stripping of Nd(III) carbonate from Nd(III)-loaded VA10, it is important to regenerate VA10 in the organic phase. For this purpose, evaporation of NH3 by air bubbling was studied. By bubbling air into a stripping solution warmed at 333 K, almost all the VA10 can be transferred to the organic phase.