The preparation of fine particles of Nd(III) carbonate from kerosene soluti
on, from which Nd(III) was extracted with versatic acid 10 (VA10) by a prec
ipitation stripping technique using an aqueous NH3-(NH4)(2)CO3 solution as
stripping medium, was studied.
In preliminary experiments, we were unable to recover Simple Nd(III) carbon
ate from Nd(III)-loaded VA10 by CO2 gas bubbling, when water, (NH4)(2)CO3,
NH4HCO3, NaHCO3, or Na2CO3 solution saturated with COP was used as the stri
pping solution.
To obtain simple Nd(III) carbonate, it is necessary to use more than the st
oichiometric amount of NH3 compared to VA10 and about 10 times as much (NH4
)(2)CO3 as Nd(III). The solution mixture of NH3-(NH4)(2)CO3 acts as a pH bu
ffer, an adductor for VA10, and a CO32- ion source. Although it was conclud
ed that the precipitates are Nd-2(CO3)(3). xH(2)O (x is approximately equal
to 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 9
73 K, hexagonal Nd2O3 was formed. Since the stripping solution consisting o
f NH3-(NH4)(2)CO3 was highly alkaline, VA10 was also stripped in the aqueou
s 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 V
A10 in the organic phase. For this purpose, evaporation of NH, by air bubbl
ing was studied. By bubbling air into a stripping solution warmed at 333 K,
almost all the VA10 can be transferred to the organic phase.