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US 9,868,647 B2Granted
System and methods for removing impurities from phosphogypsum and manufacturing gypsum binders and products
AssigneesTechnion Research & Development Foundation Limited, Vanderbilt University
InventorsKonstantin Kovler, Boris Dashevsky, David Samuel Kosson, Yonathan Reches
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Abstract
Methods and systems that remove impurities from phosphogypsum (PG), including from radium and heavy metal salts, and produce gypsum binders and products. In one embodiment, PG is reacted with a chloride solution in an acidic environment under mechanical manipulation and/or heat followed by galvanic and/or zeolite absorption removal of impurities.
Claims22
A method of removing impurities from phosphogypsum (PG), the method comprising:
- at a temperature between about 85 to about 150° C., reacting PG with a chloride solution to form a PG sludge, wherein the concentration of the chloride solution is between about 10% to about 50% and wherein metal ions present in the PG crystal matrix move into solution by action of the chloride ions present in the chloride solution;
- dehydrating a resulting sludge for about 5 minutes to about 5 hours at a temperature between about 85 to about 150° C.;
- at a cathode, galvanically removing contaminants having a lower electrode potential than hydrogen from the resulting sludge while maintaining temperature of the reaction slurry;
- filtering the resulting PG sludge to separate a solid fraction containing alpha-hemihydrate gypsum crystals from a liquid waste fraction;
- and neutralizing the alpha-hemihydrate gypsum sulfate crystal solution.
2 more elements
Dependencies are inferred from the claim text.