硅对铝酸钠溶液分解过程分解率和粒度分布的影响

Effect of silicon dioxide on the precipitation rate and particle size distribution of seeded precipitation proceeding in sodium aluminate solution

采用离子膜电解铝酸钠溶液研究硅对铝酸钠溶液快速分解过程分解率和粒度分布的影响,并用扫描电镜对自发分解产品的表面形貌进行了表征。结果表明:温度为60℃,SiO2浓度为0.90g/l时,铝酸钠溶液在前2小时分解受硅影响显著;SiO2浓度低于0.60g/l时,硅在前两小时的影响可以忽略。分解6h,含SiO2浓度小于0.9g/l的铝酸钠溶液其分解率都大于50%。硅的存在使平均粒度变细。SiO2浓度大于0.60g/l使氢氧化铝粒度分布成三态分布。SiO2浓度为0.75g/l的铝酸钠溶液析出的粒子粒度分布图中出现三态分布,且经24h成单峰分布。纯铝酸钠溶液自发分解产物表面平滑,而含硅铝酸钠溶液自发产物表面吸附很多小颗粒。

In this paper we have investigated the effect of SiO2 on the precipitation rate and particle size distribution of seeded precipitation proceeding in sodium aluminate solution by ion membrane electrolysis. Using scanning electronic microscope （SEM）, the microstructure of unseeded precipitation of aluminum hydroxide was characterized. The experiments result show that silicon dioxide influenced on precipitation ratio of aluminium - containing at the initial 2h obviously, when the silicon dioxide concentration was 0.90g/l at 60℃ . While the silicon dioxide concentration was under 0.60g/l, the initial influence on precipitation ratio may neglect. After 6h, all precipitation rates of sodium aluminate solutions with silicon dioxide below 0.9g/l were upon 50 percents. Average particle size became fine in the present of silicon. When the silicon dioxide concentration was upon 0.60g/l, three - medal particle size distribution of particle size was observed. After 24h the three - modal distribution of particJe size become one - modal distribution in the precipitation of sodium aluminate solution with 0.75g/1 silicon dioxide. The microstructure of unseeded precipitation of sodium aluminate solution with silicon dioxide comparing with precipitated from pure solution indicate that a great fine particle sizes adsorbed in the surface, this may be sodium aluminum silicate.