Method of producing calcium sulfate alpha-hemihydrate
AssigneeNational Gypsum Properties, LLC
InventorsGopalakrishnan Sethuraman, Claudette Brown, Ronald S. Finkelstein
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Abstract
A method of producing calcium sulfate α-hemihydrate, including the steps of exposing a mixture including a calcium sulfate form selected from the group consisting of calcium sulfate dihydrate, calcium sulfate β-hemihydrate, water-soluble calcium sulfate anhydrite, and mixtures thereof, water, and a crystallization catalyst, to microwave radiation to produce calcium sulfate α-hemihydrate; and separating at least a portion of the calcium sulfate α-hemihydrate to provide a solid comprising calcium sulfate α-hemihydrate and a remainder, is disclosed.
Claims30
A method of producing calcium sulfate α-hemihydrate, comprising the steps of:
- (a) exposing a mixture comprising a calcium sulfate form selected from the group consisting of calcium sulfate dihydrate, calcium sulfate β-hemihydrate, water-soluble calcium sulfate anhydrite, and mixtures thereof, water, and a crystallization catalyst, to microwave radiation to produce calcium sulfate α-hemihydrate;
- and
- (b) separating at least a portion of said calcium sulfate α-hemihydrate from the product of step (a) to provide a solid comprising calcium sulfate α-hemihydrate and a remainder.
The method of claim 23, wherein said drying step is performed by exposure to microwave radiation.
A method of producing calcium sulfate α-hemihydrate, comprising the steps of:
- (a) exposing a mixture comprising a calcium sulfate form selected from the group consisting of calcium sulfate dihydrate, calcium sulfate β-hemihydrate, water-soluble calcium sulfate anhydrite, and mixtures thereof, water, and a crystallization catalyst, to microwave radiation to produce calcium sulfate α-hemihydrate;
- and
- (b) isolating calcium sulfate α-hemihydrate from the product of step (a).
A method of producing calcium sulfate α-hemihydrate, comprising the steps of:
- forming a mixture comprising calcium sulfate dihydrate, water, and calcium chloride, wherein said calcium chloride is present at a concentration of about 2.5 molar to about 3.5 molar;
- exposing said mixture to microwave radiation to produce calcium sulfate α-hemihydrate;
- filtering at least a portion of said calcium sulfate α-hemihydrate;
- and
- washing said filtered calcium sulfate α-hemihydrate with acetone or ethanol.
Dependencies are inferred from the claim text.