【摘要】 在拜耳法生产氧化铝工业中,为了避免结疤并得到高质量的氧化铝,必须控制铝酸钠溶液中SiO2的含量。本文以氯化镁为原料合成Mg-Al水滑石(Mg6Al2(OH)16CO3.4H2O),并通过XRD,SEM及粒度分析仪对所合成的Mg-Al水滑石进行了表征。并以合成的Mg-Al水滑石为添加剂对铝酸钠溶液中的脱硅进行了研究,分别考察了Mg-Al水滑石的合成温度、脱硅温度、脱硅时间、NaOH浓度、Al2O3浓度、溶液中SiO2的初始浓度,Mg-Al水滑石添加量对脱硅效果的影响,并对Mg-Al水滑石与CaO的脱硅效果进行了比较。实验结果表明用Mg-Al水滑石作为脱硅剂时,可使铝酸钠溶液中脱硅效率达到95%以上,Mg-Al水滑石的脱硅效果优于CaO。同时探讨了Mg-Al水滑石的脱硅机理。更多还原

【Abstract】 Controlling SiO2 contents in sodium aluminate solution in Bayer process is very important.In this paper,Mg-Al hydrotalcite(Mg6Al2(OH)16CO3·4H2O) was prepared by magnesium chloride and characterized by XRD,SEM and Grain size analyzer.Furthermore,the desilication of sodium aluminate solution with synthesized Mg-Al hydrotalcite was studied.The experimental parameters affecting the desilication process,such as synthesis temperature of Mg-Al hydrotalcite,desilication temperature,desilication time,NaOH concentration,Al2O3 concentration,the initial SiO2 concentration,Mg-Al hydrotalcite dosage,and the comparison of desilication effect between Mg-Al hydrotalcite and CaO were investigated in detail.The results displayed that Mg-Al hydrotalcite could remove up to 95% silica from sodium aluminate solution and Mg-Al hydrotalcite had better desilication effect than CaO.The desilication mechanism with Mg-Al hydrotalcite was also discussed in this paper.更多还原