无机阴离子对低温拜耳法中脱硅产物析出的影响

Effect of inorganic anions on precipitation of desilication products based on low-temperature Bayer process

利用XRD、FT-IR、SEM和PSD等手段系统研究无机阴离子对低温拜耳法过程中脱硅产物(DSPs)的组成、结构以及微观形貌的影响。当溶液中存在氯化物、硫酸盐和碳酸盐时,形成氯化物型方钠石、碳酸盐型方钠石和黝方石,部分铝酸盐离子被阴离子杂质取代。硫酸盐与DSPs的结合能力强于铝酸盐、氯化物和碳酸盐。随着阴离子浓度的增加,DSPs的粒径增大,且DSPs的团聚程度和圆形片层结构的厚度均有所增加。此外,阴离子杂质会促进沸石骨架的溶解和方钠石中四元环的形成,从而促进沸石向方钠石转化。

The effect of inorganic anion impurities in sodium aluminate solution on the composition,structure and micro-morphology of desilication products(DSPs)based on the low-temperature Bayer process was systematically investigated via XRD,FT-IR,SEM and PSD methods.The sodalites with chloride-type,carbonate-type and nosean-type precipitate in the presence of chloride,sulfate and carbonate in solution,and the aluminate ions in DSPs are partly replaced by the incorporation of anion impurities.The binding capability of sulfate to the DSPs cage is stronger than aluminate,chloride and carbonate.The particle size,agglomeration degree and thickness of the circular lamellar structure of DSPs are increased by rising the concentration of anion impurities.The anions enhance the dissolution of the zeolite framework and the formation of tetradentate rings in sodalite,which promotes the transformation of zeolite to sodalite.