Crystalline zeolite powder of type A (VI)

A process of preparing a crystalline zeolite powder of Type A with the composition:

• 1.0.+-.0.2M.sub.2/n O:Al.sub.2 O.sub.3 :1,85.+-.0.5SiO.sub.2.yH.sub.2 O
• where M is a metal cation, n is its valence and y has a value up to 6 with 50 weight % of the particles not over 5.9.mu. and with a particle spectrum:
• ______________________________________ Fraction (.mu.) Portion (weight %) ______________________________________ <3 15 to 25 <5 35 to 55 <10 80 to 94 <15 96 to 100 ______________________________________
• comprising hydrothermally crystallizing a SiO.sub.2, Al.sub.2 O.sub.3, M.sub.2 O and water containing alkali aluminate, water, alkali silicate synthesis mixture where M is sodium, said process including the steps of providing water in a container, simultaneously feeding into the water at a temperature of 30.degree. to 100.degree. C. an aqueous sodium aluminate liquor containing 100 to 200 grams/l of Na.sub.2 O and 50 to 150 grams/l of Al.sub.2 O.sub.3 and sodium silicate solution containing 50 to 150 grams of Na.sub.2 O/l and 200 and 450 grams of SiO.sub.2 /l, wherein the proportion of the water in the container to the aqueous sodium aluminate liquor is 2 to 4:1 by volume, diluting with water to obtain a gel containing synthesis premixture having the composition SiO.sub.2 /Al.sub.2 O.sub.3 =2 to 50:1, Na.sub.2 O/SiO.sub.2 =0.2 to 20:1 and H.sub.2 O/Na.sub.2 O=4 to 300:1 adding further sodium aluminate liquor of the same composition and water having a temperature of 10.degree. to 100.degree. C. with stirring and wherein the proportion of sodium aluminate liquor to the water is 6 to 10:1 by volume and allowing the thus obtained synthesis mixture to crystallize at a temperature within between 20.degree. and 175.degree. C. in at least 15 minutes.