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US 6,517,790 B1Granted
Converting fluorgyp to calcium sulfate
AssigneeAlcoa Inc.
InventorDennis J. Eisele
Life of this patent
Estimating the term…
Abstract
Fluorgyp is converted to calcium sulfate by reacting sulfuric acid in the fluorgyp with calcium carbonate having a small particle size. The resulting product is useful as a set retarding agent for cement.
Claims13
A process for converting fluorogypsum to calcium sulfate useful as a set retarding agent for cement, comprising
- (a) providing powdered fluorogypsum comprising calcium sulfate contaminated with sulfuric acid, and
- (b) reacting said sulfuric acid in the fluorgypsum with calcium carbonate thereby neutralizing at least most of said sulfuric acid, the resulting product comprising calcium sulfate.
A process for making calcium sulfate, comprising
- a) providing calcium sulfate contaminated with about 0.1-4 wt % sulfuric acid,
- b) reacting said sulfuric acid with calcium carbonate having an average particle size of about 15 microns or less, thereby to form a product comprising calcium sulfate and water,
- c) removing said water from the product.
Dependencies are inferred from the claim text.