脱硅产物在铝酸钠溶液中常压析出的矿相转变（英文）

Mineral transition of desilication products precipitated in synthetic sodium aluminate solution under atmospheric pressure

研究在95°C下合成过饱和二氧化硅铝酸钠溶液时不同脱硅条件对脱硅产物的生成量、物相组成及其结晶度和显微组织的影响规律。在常压脱硅条件下,脱硅产物由无定型沸石、A型沸石、沸石和方钠石组成;脱硅产物的生成量和结晶度随着初始二氧化硅浓度、分子比和脱硅时间的增加而增加。降低初始二氧化硅浓度和分子比,增加脱硅时间,能够降低A型沸石的含量。沸石和方钠石是稳定的脱硅产物,而A型沸石只在高饱和二氧化硅浓度的铝酸钠溶液中析出。脱硅产物析出后均发生附聚,但不同类型脱硅产物的显微形貌明显不同;脱硅产物中Na_2O与Al_2O_3摩尔比、SiO_2与Al_2O_3摩尔比随着脱硅时间的增加而增大,从而使脱硅产物的晶胞体积增大。常压下过饱和二氧化硅铝酸钠溶液中脱硅产物的析出顺序为:无定型沸石→A型沸石→沸石→方钠石。

The liquor concentration, mineral proportion, crystal parameters and micro morphology of various desilication products（DSPs） precipitated in silica-supersaturated sodium aluminate solution at 95 ℃ under different reaction conditions were systematically researched. The DSPs formed under atmospheric pressure comprise amorphous phase, zeolite A, zeolite and sodalite, and the DSPs concentration and crystallinity increase with the increase of initial silica concentration, initial molar ratio of caustic Na2O to Al2O3（αK） and desilication duration. Decreasing the initial silica concentration, initial αK and increasing the desilication duration can reduce the proportion of zeolite A. The zeolite and sodalite are the stable DSPs, while the precipitation of zeolite A occurs at a high silica-supersaturated state in sodium aluminate solution. The DSPs are precipitated in the form of agglomerates, but the morphologies of various DSPs are quite different. Both the molar ratios of Na2O to Al2O3 and SiO-2 to Al2O3 in DSPs increase with the increasing desilication duration, resulting in the increase of the cell volumes of various DSPs. The precipitation sequence of DSPs under atmospheric pressure is： amorphous phase→zeolite A→zeolite→sodalite.