Metastable Dissolution Regularity of Nd in NaCO Solution and Mechanism.

The carbonate solution-dissolved rare earth showed some metastable chemical characteristics. In this paper, the systematic investigation of metastable dissolution regularity of Nd in NaCO solution was carried out. The results showed that Nd has an instantaneous saturated solubility in NaCO solution. When the amount of the dissolution Nd did not reach the instantaneous saturated solubility, the solution was in a stable-state period. Once the concentration of Nd exceeded the instantaneous saturated solubility, the solution was no longer in the metastable state and generated the neodymium double salt of carbonate precipitates rapidly. The molecular dynamics simulation of the solution in the metastable state was carried out. In high concentration NaCO solution, dissolved Nd had a coordination reaction with the CO . Also, there was a stronger interaction between Na and CO , which caused the effective concentration of free CO which could react with Nd to become lower. Thus, these reasons make the solution exhibit a metastable state. In that metastable period, the dissolved Nd becomes steady and hard to generate the neodymium double salt of carbonate precipitates.