CA2402679C — Process for manufacture of zeolites and zeolite mixtures having enhanced cation exchange properties, products produced thereby, and detergent compositions formulated therewith

USPTO Abstract

A zeolite A or an A/X mixture having an LCC > 70 g liquid/100g zeolite (hydrated) and a cold water CER > 200 mg CaCO3/gram anhydrous zeolite (hydrated). The zeolite product may have a crystal size of 0.1-0.7 microns, a bulk density o f 0.19-0.37 g/ml, and a median particle size of 1-5 microns. A process for making zeolite A or A/X mixtures is also claimed, including mixing a sodium silicate solution, a sodium aluminate solution, and an amorphous aluminosilicate initiator gel in a mixing vessel to create an aluminosilicate synthesis gel, and crystallizing the aluminosilicate synthesis gel to form zeolite crystals. The sodium aluminate solution may be added gradually to at least the sodium silicate solution at a rate of about 1-5% of the total batch alumina per minute, and/or a percentage of the total batch alumina may be added as alumina trihydrate (ATH) powder. The amount of total batch alumina added as an undissolved source of soluble alumina and the presence or absence of initiat or or "seed" gel determines whether the resulting zeolite product is an A/X mixture or only zeolite A. A process to augment the yield of a synthesis mixture is also claimed, comprising providing undissolved alumina in substantial excess of stoichiomeric requirements in a primary crystallization step, yielding a slurry of crystalline zeolite A in an alumina-enriched mother liquor, and then adding soluble silicate to initiate a second stage of very rapid crystallization. Detergents containing zeolites of this invention are claimed.