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US 10,392,260 B2Granted
Method of treating phosphate-containing ash from waste-incineration plants by wet-chemical digestion in order to obtain compounds of aluminium, calcium, phosphorus and nitrogen
AssigneeRemondis Aqua GmbH & Co. KG
InventorsJosef Lehmkuhl, Martin Lebek
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Abstract
The invention concerns a method of treating phosphate-containing waste, in particular phosphate-containing ash from waste-incineration plants, by wet-chemical digestion in order to obtain compounds of aluminum, calcium, phosphorus and nitrogen.
Claims20
A method for obtaining precipitates of calcium sulphate (CaSO4) and for production of phosphoric acid from phosphate-containing ashes from waste incineration plants, characterized in that
- a) combining the phosphate-containing ashes with phosphoric acid to cause a reaction,
- b) separating an acid-insoluble portion of the phosphate-containing ashes from the reaction of step a),
- c) adding sulfuric acid to a filtrate or supernatant of step b) and thereby adjusting the pH to <1, to obtain and separate calcium sulphate precipitate and to thereby also obtain purified phosphoric acid as the filtrate or the supernatant of step c),
- d) recycling at least partially the filtrate or supernatant of step c) as the phosphoric acid for use in step a).
1 more element
Dependencies are inferred from the claim text.