Crystallization of zeolite Y formation in the process of mother liquor recy
cling (MLR) has been studied. The zeolite crystallization mother liquor com
prises a little sodium silicate as well as minor zeolite, Upon addition of
aluminum sulfate, the silicate existed in the mother liquor reacts to form
finely divided silica-alumina hydrogel (MLHG) which can be utilized later i
n zeolite Y formation. The particle of MLHG is relatively small and Si/Al o
f the gel's framework is a little great. Since amorphous aluminosilicate ge
l passes through two stages of gelation, the pseudoequilibrium between soli
d phase and liquid phase of gel is attained rapidly and the time of zeolite
Y formation is much reduced. In addition, experiments have also showed tha
t the quantities and the properties of zeolite Y added affect the process o
f crystallization heavily. Minor quantities of zeolite in the mother liquor
have detrimental effect on the zeolite Y formation. Based on studies of cr
ystallization from recycling mother liquor, a model of two-phase transforma
tion for zeolite Y formation has been proposed. (C) 1998 Elsevier Science B
.V. All rights reserved.