苛碱浓度对种分产品粒度变化规律的影响

氢氧化铝产品粒度存在周期性爆发性细化是我国氧化铝生产中拜耳法部分固有的现象，它严重干扰了拜耳法系统的正常运行.为探明产品粒度周期性细化的机理，在实验室模拟工业条件，结合激光粒度分析仪与扫描电子显微镜，研究了苛碱浓度对种分过程产品粒度周期性细化的影响规律.结果表明：铝酸钠溶液苛碱浓度增加，产品粒度波动的振幅变大，细化时间延长；苛碱浓度降低，产品粒度发生爆发性二次成核时间较早，但细化后粒度恢复为粗颗粒的速度较快.溶液浓度的变化对溶液分解率也有较大影响，降低溶液浓度能提高铝酸钠溶液的分解率.

Effect of caustic sodium concentration on variation rule in particle size of crystal seed precipitation product

The periodic and explosive attenuation of particle size in aluminum hydroxide is an inherent phenomenon for alumina production with Bayer process in our country,which seriously interferes with the normal operation of the Bayer process system.In order to clarify the periodic attenuation mechanism of particle size,the industrial conditions were simulated in laboratory,and the effect of caustic sodium concentration on variation rule in particle size of crystal seed precipition product was studied in combination with laser particle size analyzer and sanning electron microscope.The results show that with increasing the caustic sodium concentration in sodium aluminate solution,the fluctuation amplitude of particle size increases,and the attenuation time prolongs.With decreasing the caustic sodium concentration,the explosive secondary nucleation of particle occurs earlier,but the speed for the particles after attenuation to coarsen is faster.In addition,the variation of solution concentration has great influence on the precipitation rate of the solution,and the precipitation rate of sodium aluminate solution can be enhanced with decreasing the solution concentration.