摘要
0引言氧化钕是稀土行业中商品量最大的产品之一.因此,采用碳酸盐代替目前广泛采用的草酸来沉淀钕和生产氧化钕具有十分重大的经济和社会效益.有关稀土碳酸盐的制备、性质和应用的研究已有一些报道[1～20],作者提出了一套可以实现间歇和连续操作的稀土碳酸盐结晶沉淀方法[7].
The characteristics of pH value variation during aging process of amorphous neodymium carbonate formed by three different feeding manners have been investigated. The promotion action of seeding on the crystallization of neodymium carbonate is discussed. X-ray diffraction pattern and the elemental analysis results show that neodymium carbonate can transfer from amorphous to crystalline normal neodymium carbonate Nd-2(CO3)(3)(.)8H(2)O with lanthanide structure at room temperature. Its crystallization activity zone lies in lower feeding ratio area expressed by nNH(4HCO3)/n(Ndcl3), between 2 similar to 3. The existing of seeds can shorten crystalline time, from more than 15 h without seed to 2 It with seeds under normal feeding manner. And the spontaneity nucleation time can be shortened further when feeding with multi-steps normal manner. However, whether multi-steps normal or synchronously and continuously feeding manner, the precipitate formed can transfer to crystalline neodymium carbonate directly under seeding. At the same time, it is observed that the variation of pH value reduces with the decrease of feeding amount and the shortening of aging period, indicating that with synchronously and continuously feeding manner can not only realize fast crystallization, but also control pH value within a narrow range, which is beneficial for the producing of neodymium carbonate crystal with narrow-distributed particle size and monitoring of its crystallization process.
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
2005年第8期1213-1217,共5页
Chinese Journal of Inorganic Chemistry
基金
国家自然科学基金(No.59764001)
江西省自然科学基金(No.Q97001)资助项目。
关键词
碳酸钕
晶种
结晶
pH值原位测定
neodymium carbonate
seed
crystallization
pH determination in situ
