Process for preparing a pyrophosphate-silicate detergent product

Claim 1

A detergent composition prepared by the process of: 1. forming an aqueous slurry comprising a. from about 2 to about 20% on a dry weight basis of an alkali metal silicate having the formula SiO 2 :M 2 O, wherein the SiO 2 :M 2 O weight ratio is from about 2.4:1 to about 4:1, and M is an alkali metal or mixtures thereof; b. from about 9 to about 50% on a dry weight basis of an alkali metal pyrophosphate having the formula M x H y (P 2 O 7 ) and the sum of x + y are integers equal to 4; M is an alkali metal or mixtures thereof; c. from about 0.1 to about 80% on a dry weight basis of a diluent selected from the group consisting of natural and synthetic clays, alkali metal carbonates, bicarbonates, and sesquicarbonates, borates, perborates, sulfates, chlorides, bisulfates, aluminates, and calcium carbonate, and mixtures thereof; d. from about 5 to about 40% on a dry weight basis of an anionic, nonionic, zwitterionic, or ampholytic detergent and mixtures thereof; then, 2. spray drying the slurry of (1) to form an alkaline solid granular detergent composition characterized in that when 1.2 grams of the alkaline solid granular detergent composition are added to one liter of distilled water at 25° C, agitated for one minute to avoid lumping, and filtered through a 142 mm diameter, five micron pore size filter under nitrogen at 6.8 atmospheres pressure, the molar ratio of the filtrate SiO 2 to the total SiO 2 from the silicate in the complete alkaline detergent composition is no more than about 3.3:4, and 3. admixing from about 0 to about 60% on a dry weight basis of the material described in (1)(b) to give a detergent composition combining from about 12% to about 45% by weight M 4 (P 2 O 7 ) wherein M is an alkali metal; wherein the total amount of alkali metal tripolyphosphate present is less than about 20% by weight of the total pyrophosphate present and wherein the total detergent composition contains from about 0.1% to about 4% by weight of a glassy phosphate of the formula (M.sub.2 O).sub.x (P.sub.2 O.sub.5).sub.y wherein y is from about 5 to 50 and the ratio of y:x is from about 1:1 to about 1:1.5 and M is an alkali metal.