Patent ID: 8016960
Filing Date: 2011-09-13
Classification: B01F,B28B,B28C,C04B

Abstract:
1. A method of introducing a wet gypsum accelerator (WGA) to a post-mixer aqueous dispersion of calcined gypsum, the method comprising: forming an aqueous dispersion of calcined gypsum in a mixer chamber; discharging the aqueous dispersion into a discharge apparatus, wherein the discharge apparatus is operatively connected to the mixer chamber; introducing the WGA into the aqueous dispersion within the discharge apparatus, wherein the WGA has a viscosity of about 2000 centipoises to about 4000 centipoises, wherein the ratio of WGA viscosity to aqueous dispersion viscosity is between about 10:1 to about 2:1, and wherein the WGA comprises: (a) calcium sulfate dihydrate, (b) water, wherein the water is present in an amount of from about 55% to about 65% by weight of said accelerator, (c) an organic phosphonic compound selected from the group consisting of aminotri (methylene-phosphonic acid), aminotri (methylene-phosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, diethylenetriamine penta(methylene phosphonic acid), diethylenetriamine penta(methylene phosphonic acid), hexamethylene diamine tetra(methylene phosphonic acid), hexamethylene diamine tetra(methylene phosphonic acid), a pentasodium salt, trisodium salt, tetrasodium salt, sodium salt, ammonium salt, potassium salt, calcium salt, or magnesium salt of any of the foregoing acids, and combinations thereof, and (d) a phosphate-containing compound selected from the group consisting of tetrapotassium pyrophosphate, sodium acid pyrophosphate, sodium tripolyphosphate, tetrasodium pyrophosphate, sodium potassium tripolyphosphate, sodium hexametaphosphate salt having from 6 to about 27 phosphate units, ammonium polyphosphate, sodium trimetaphosphate, and combinations thereof.