Aluminum Phosphate Ceramics for Waste Storage
AssigneeCH2M Hill, Inc.
InventorsArun Wagh, Martin D. Maloney
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Abstract
The present disclosure describes solid waste forms and methods of processing waste. In one particular implementation, the invention provides a method of processing waste that may be particularly suitable for processing hazardous waste. In this method, a waste component is combined with an aluminum oxide and an acidic phosphate component in a slurry. A molar ratio of aluminum to phosphorus in the slurry is greater than one. Water in the slurry may be evaporated while mixing the slurry at a temperature of about 140-200° C. The mixed slurry may be allowed to cure into a solid waste form. This solid waste form includes an anhydrous aluminum phosphate with at least a residual portion of the waste component bound therein.
Claims54
A method of processing waste, comprising:
- combining a waste component with an aluminum oxide and an acidic phosphate component in a slurry comprising water, wherein the waste component comprises hazardous waste and a molar ratio of aluminum to phosphorous in the slurry is greater than one;
- evaporating water in the slurry while mixing the slurry at a functional temperature of about 140-200° C.;
- and
- allowing the mixed slurry to cure into a solid waste form comprising an anhydrous aluminum phosphate with a residual portion of the waste component bound therein.
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A method of producing a stable waste form, comprising:
- reacting an aluminum oxide with an acidic phosphate component in a first slurry;
- at least partially drying the first slurry at a first temperature to form a phosphate precursor;
- mixing the phosphate precursor and a waste in a second slurry at a second temperature of about 106-175° C. while allowing water in the second slurry to evaporate;
- after at least a majority of the water in the second slurry is evaporated, allowing the mixed second slurry to cure into a solid waste form including a remaining portion of the aluminum oxide distributed in a matrix comprising an anhydrous aluminum phosphate and at least a portion of the waste.
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A method of producing a stable, low-volume waste form from a radioactive material, comprising:
- mixing the radioactive material with an aluminum oxide and an acidic phosphate to form a slurry, a molar ratio of aluminum to phosphorous in the slurry being between about 2 and about 5, and the aluminum oxide comprising hydrous alumina, anhydrous alumina, or aluminum hydroxide;
- heating the slurry to a first temperature that is no greater than about 200° C., but is at least as great as a dissolution temperature of the aluminum oxide with the acidic phosphate;
- while mixing the slurry, evaporating water from the slurry at a second temperature of about 140-175° C. until a substantial majority of the water is evaporated;
- after the water evaporation, allowing the resultant evaporated product to cure as a solid waste form comprising aluminum oxide particles and at least a portion of the radioactive waste in a matrix comprising substantially anhydrous AlPO4.
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A solid waste form comprising:
- a matrix comprising a substantially anhydrous aluminum phosphate and a phosphate of a heavy metal;
- a radioactive material distributed in the matrix;
- and
- aluminum oxide particles distributed in the matrix.
Dependencies are inferred from the claim text.