钨酸铵-硝酸铵溶液体系结晶制备仲钨酸铵过程中钠/钾的析出行为（英文）

Sodium/Potassium Precipitation Behavior during Evaporative Crystallization of Ammonium Paratungstate from Ammonium Tungstate/Nitrate Solution

研究了在钨酸铵-硝酸铵溶液体系制备仲钨酸铵过程中,硝酸铵添加量、杂钨比、反应温度等因素对钠/钾析出的影响.结果表明,仲钨酸钠/钾比仲钨酸铵更易沉淀,且仲钨酸钾最易沉淀.添加硝酸铵可有效抑制钠/钾沉淀,且抑制作用随硝酸铵浓度增加而增大.随温度升高和钠/钾含量降低,析出物中钠/钾含量降低.在硝酸铵添加量20 g/L、初始钠含量0.100 g/L、初始钾含量0.030 g/L、反应温度95℃的条件下反应,产品中的钠/钾含量能达到国家标准.

The effects of several factors, including the amount of ammonium nitrate added, mass ratio of sodium/potassium to tungsten, and reaction temperature, on the precipitation of sodium/potassium during evaporative crystallization of ammonium paratungstate from ammonium tungstate/ammonium nitrate solution system were investigated. The results showed that sodium/potassium paratungstate was precipitated more readily than ammonium paratungstate（APT）. Further, the precipitation of sodium/potassium can be inhibited by adding ammonium nitrate during the crystallization of ammonium paratungstate from the ammonium tungstate solution. The inhibitory effect of ammonium nitrate on the precipitation of sodium/potassium increases with the increase of ammonium nitrate concentration. The sodium/potassium content in the precipitate decrease with a increases of crystallization temperature and an decrease of sodium/potassium content in the solution. The sodium/potassium content in APT can be less than the recommended limit when concentration of ammonium nitrate is 20 g/L, concentration of initial sodium was 0.100 g/L, initial concentration of potassium was 0.030 g/L, and crystallization temperature was 95 ℃.