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US 8,016,960 B2Granted
Methods of and systems for adding a high viscosity gypsum additive to a post-mixer aqueous dispersion of calcined gypsum
AssigneeUnited States Gypsum Company
InventorsJames R. Wittbold, W. David Song
Life of this patent
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Abstract
Provided are methods and systems for introducing a wet gypsum accelerator or other high viscosity production additive to an aqueous dispersion of calcined gypsum in a discharge apparatus downstream of a stucco mixer in which the dispersion was prepared. These methods and systems are useful in the production of various gypsum products such as board including wallboard and ceiling tiles.
Claims31
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.
5 more elements
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 2500 to about 5500 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 aminotri (methylene-phosphonic acid), aminotri (methylene-phosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, 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.
5 more elements
Dependencies are inferred from the claim text.