Treating calcined gypsum with solubilizing agent
AssigneeUnited States Gypsum Company
InventorLarbi Bounini
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Abstract
A process for producing a healed stucco of low water demand is disclosed in which calcined gypsum is treated with an aqueous solution of a gypsum solubilizing agent, preferably in an impacting blender while grinding the calcined gypsum to increase its surface area. The product can be dried for storage or sent directly to forming gypsum board.
Claims7
A method of treating beta calcium sulfate hemihydrate having an initial high consistency which method comprises treating said hemihydrate with about 1-10 weight % of aqueous medium consisting of water and about 0.01-1 mole per liter of a gypsum solubilizing agent selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, boric acid, chromic acid, sodium chloride, sodium nitrate, sodium nitrite, sodium carbonate, sodium bicarbonate, rochelle salt, potassium chloride, potassium nitrite, ammonium chloride, ammonium nitrate, ammonium carbonate, ammonium phosphate, ammonium oxylate, magnesia, borax, and mixture thereof to achieve an at least about 10% reduction, as compared to treating with water without said solubilizing agent, in dispersed consistency or healing time of the treated hemihydrate.
A method of treating a beta hemihydrate having a high initial consistency with about 21/2-3%, by weight of the hemihydrate, of an about 0.2 molar aqueous solution of sodium hydroxide to achieve a substantial reduction as compared to treating with water without said solubilizing agent in consistency in less than about 1 minute.
Dependencies are inferred from the claim text.