Prepn. of finely divided crystalline sodium aluminium silicate

摘要

In prepn. of finely divided crystalline Na Al silicates of compsn. (I) 0.9-1.1 Na20:1 Al203:1.8-3.6 Si02 by crystallisation of an aq. suspension of X-ray amorphous Na Al silicate (II) at raised temp., (a) (II) is obtd. by pref. continuous mixing of an aq. Na aluminate soln. with an aq. Na silicate soln. in presence of excess NaOH soln. at raised temp., with the ppte. being led, during the mixing or later, but before crystallisation, through an agitator ball mill suitable for wet grinding, in which the apparent vol. of the balls is more than 50% (75-85%) of the vol. of the mill chamber, with a residence time in the mill of 3-40 (5-15) secs., at 40-80 (50-70) deg.C, and (b) crystallisation is continuous.