中文摘要：

采用化学沉淀法进行盐水精制是氯碱工业的关键过程之一。今采用陶瓷膜脱除盐水中的沉淀物,考察了气升条件下盐水中化学沉淀物（CaCO3、BaSO4、Mg（OH）2）对陶瓷膜过滤过程的影响。结果表明,曝气对三种体系均可显著提高膜的渗透通量,含CaCO3盐水体系的膜通量与含BaSO4体系相当,是含Mg（OH）2体系膜通量的1.5倍;当曝气量大于300 L h 1时,进一步增大曝气量对含CaCO3、BaSO4体系的盐水渗透通量影响不大,但可使含Mg（OH）2体系盐水渗透通量提高50%以上;跨膜压差与通量基本呈线性增大关系,跨膜压差对CaCO3、BaSO4体系通量的影响大于对Mg（OH）2体系的影响;固含量增大,由于体系黏度显著增大,使三种体系的膜通量均呈下降趋势,含Mg（OH）2体系的通量下降最大。对盐水中沉淀物的分析结果表明,方解石相的CaCO3颗粒分散均匀,粒径为16.08μm,表面电势为16.5mV;重晶石相的BaSO4颗粒粒径在2.18μm左右,表面电势为33 mV;而无定形的Mg（OH）2颗粒粒径分布宽,平均粒径1.59μm,表面电势为18 mV。由于粒径与荷电性的双重作用,使得CaCO3、BaSO4体系膜过滤阻力相近,小于Mg（OH）2体系的膜过滤阻力;钙镁离子共沉淀中,随着钙离子量的增大,膜过滤通量增大。

英文摘要：

Brine purification with chemical precipitation is one of the key processes in chlor-alkali industry.In this paper,the influence of the chemical precipitates（CaCO3,BaSO4 and Mg（OH）2） on the filtration process of ceramic membrane with the help of airlift was investigated.The results show that the aeration can significantly enhance the membrane fluxes during the filtrations of these three suspension systems.The filtration flux of CaCO3 or BaSO4 suspension system is more than 1.5 times of that of these Mg（OH）2 system,and when the exposed gas volume is greater than 300 L？h？1,the flux of CaCO3 or BaSO4 suspension system has little change with the further increase of the amount of aeration,but it can increase the flux of Mg（OH）2 system more than 50%.The fluxes of the above three systems basically increase linearly with the increase of the transmembrane pressure.Since the solid content increase will cause the significant increase of the system viscosity,the membrane fluxes of these three systems show a decreasing trend with the solid content increase.The brine sediment analysis results show that the calcite phase of CaCO3 particles uniformly disperse with the particle size of 16.08 μm and the surface potential of ？16.5 mV;the barite phase BaSO4 particle size is about 2.18 μm and the surface potential is ？33 mV;the amorphous Mg（OH）2 particle size distribution is wide with an average particle size of 1.59 μm and surface potential of ？18 mV.Because of the effects of both the size and surface charge of the particles,the membrane filtration resistances of CaCO3 and BaSO4 suspension systems are similar,but they are far different from that of Mg（OH）2 suspension system.It was found that,in the co-precipitation process of the system consisted of calcium and magnesium ions,the membrane filtration flux increases with increasing the portion of calcium ion.