氯化钾间歇冷却结晶生长规律及粒度控制实验研究

Experimental research on growth and crystal size control of potassium chloride in batch cooling crystallization

采用聚焦光束反射测量技术(FBRM)考察了氯化钾(KCl)间歇冷却结晶过程中晶体成核和生长规律,重点研究了降温速率对KCl水溶液冷却时产生过饱和度的影响,以及添加晶种的相关条件(如晶种粒径和添加量等因素)与KCl晶体产品粒度的关系。同时,采用直接冷却刺激起晶产生“晶种”,并控制其生长达到控制晶体产品粒度的目的。结果表明,在添加晶种条件下,程序降温过程产生的低过饱和度不易引起爆发成核,且晶种的添加量决定着晶体产品的平均粒度与理想生长模型的偏差。另外,降温速率是冷却刺激起晶产生“晶种”粒径的关键因素。

The crystal nucleation and growth of potassium chloride(KCl) in the batch cooling were investigated by focused beam reflectometry(FBRM).The effects of cooling rate on the supersaturation of KCl aqueous solution during cooling,and the relationship between the relevant conditions of seed addition(such as the seed particle size and the addition dosage) and the particle size of the KCl crystal product were studied.Meanwhile,"seed" was produced by crystallization stimulated by direct cooling and was controlled its growth to achieve the purpose of controlling the crystal product size.Results showed that the low supersaturation generated in the programmed cooling process was not easy to cause explosive nucleation under the condition of adding seed,and the addition dosage of seed determined the deviation of the average particle size of the crystal product from the ideal growth model.In addition,the cooling rate was a key factor in determining the particle size of the“seed” obtained by coolingstimulated crystallization.