铝酸钠溶液添加活性晶种分解过程颗粒的演变

Particles evolution during seeded precipitation of sodium aluminate solution by adding active seed

以碳酸氢钠诱导铝酸钠溶液分解制备活性晶种,研究了添加极少量该活性晶种铝酸钠溶液分解过程中的颗粒演变规律。结果表明:随着分解过程的进行,产品粒度先增大而后减小,其拐点对应于铝酸钠溶液过饱和度变化速率由快变慢的转折点。种分初期,产品中拜耳石含量高,并存在数量较多的附聚体,拜耳石为粘结相。种分后期,拜耳石被较高苛性比的铝酸钠溶液溶解,导致附聚体解体而使产品细化。研究结果可为研究铝酸钠溶液添加活性晶种分解过程的粒度控制技术提供借鉴。

The variations of product particles were investigated during the precipitation with extremely low addition of active seed prepared by NaHCO3-induced precipitation of sodium aluminate solution.The results show that,with the proceeding of precipitation,the particle size of the precipitated product first increases and then decreases,and the maximum size of the product appears at the transition point of solution supersaturation variation.In the early period of the precipitation,the precipitate principally contains bayerite and a quantity of agglomerates are formed using bayerite acting as a binder.The bayerite binder is dissolved by sodium aluminate solution with high caustic molar ratio in the late period of precipitation,resulting in the disintegration of agglomerates and thus decreasing the product size.The research results allows to provide guidelines for particle size control in the precipitation process of sodium aluminate solution by adding active seed.