# US 2016/0257574 A1 · 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 > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2016/0257574 A1 - Document ID: US20160257574A1 - Status: Published application - Kind: A1 - Application number: 15/034,819 - Filed: 2014-05-20 - Published: 2016-09-08 - Earliest claimed: 2013-11-06 - Assignees: Remondis Aqua GmbH & Co. KG - Applicants: Remondis Aqua GmbH & Co. KG - Inventors: Josef Lehmkuhl; Martin Lebek - Web page: https://patentgrep.com/patent/US20160257574A1 ## CPC - C01F 11/46: Sulfates (dehydration of gypsum {for the production of calcium sulfate cements} C04B11/02) - C01B 25/32: Phosphates of magnesium, calcium, strontium, or barium - C01B 25/322: {Preparation by neutralisation of orthophosphoric acid} - C01B 25/36: Aluminium phosphates - C01F 11/36: Nitrates - C01F 11/38: Preparation with nitric acid or nitrogen oxides - C05B 11/06: using nitric acid (nitrophosphates) - C01F: COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides or polysulfides of magnesium, calcium, strontium, or barium C01B17/42; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia or cyanogen containing nitrogen and non-metals and optionally metals C01B21/082; amides or imides of silicon C01B21/087}; metal {imides or} amides C01B21/092, {C01B21/0923}; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20; {double sulfates of magnesium with sodium or potassium C01D5/12; with other alkali metals C01D15/00, C01D17/00}) - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} - C05B: PHOSPHATIC FERTILISERS ## 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 aluminium, calcium, phosphorus and nitrogen. ## Claims ### Claim 1 A method for obtaining (generating) precipitates selected from the group of calcium nitrate (CaNO3), calcium phosphate (Ca3(PO4)2), calcium sulphate (CaSO4), and aluminium hydroxophosphate (Al(OH)3×AlPO4); from phosphate-containing ashes from waste incineration plants, the method comprising at least the obtaining (generation) of calcium phosphate (Ca3(PO4)2) and calcium nitrate (CaNO3), characterized in that a) the solids (ash) are reacted with nitric acid or phosphoric acid or a mineral acid mixture of these two acids, b) the acid-insoluble portion of the solids is separated, c) calcium phosphate precipitate and calcium nitrate precipitate is obtained and separated by addition of calcium oxide or calcium carbonate to the filtrate or supernatant. ### Claim 2 (depends on 1) Method according to claim 1, additionally comprising the obtaining (generation) of calcium sulphate (CaSO4), characterized in that a) the solids (ash) are reacted with nitric acid or phosphoric acid or a mineral acid mixture of these two acids, b) the acid-insoluble portion of the solids is separated, c) calcium sulphate precipitate is obtained and separated by adding sulfuric acid to the filtrate or supernatant, d) calcium phosphate precipitate and calcium nitrate precipitate is obtained and separated by the addition of calcium oxide or calcium carbonate to the filtrate or supernatant. ### Claim 3 (depends on 1) Method according to claim 1 additionally comprising the obtaining (generation) of aluminium hydroxophosphate (Al(OH)3×AlPO4), characterized in that a) the solids (ash) are reacted with nitric acid or phosphoric acid or a mineral acid mixture of these two acids, b) the acid-insoluble portion of the solids is separated, c) calcium sulphate precipitate is optionally obtained and separated by adding sulphuric acid to the filtrate or supernatant, d) the dissolved aluminium as aluminium hydroxophosphate precipitate is obtained and separated by raising the pH-value, e) calcium phosphate precipitate and calcium nitrate precipitate is obtained and separated by addition of calcium oxide or calcium carbonate to the filtrate or supernatant. ### Claim 4 (depends on 1) Method according to claim 1 comprising the obtaining (generation) of precipitates selected from the group of calcium nitrate (CaNO3), calcium phosphate (Ca3(PO4)2), calcium sulphate (CaSO4), and aluminium hydroxophosphate (Al(OH)3×AlPO4); from phosphate-containing ashes from waste incineration plants, characterized in that a) the solids (ash) are reacted with nitric acid or phosphoric acid or a mineral acid mixture of these two acids, b) the acid-insoluble portion of the solids is separated, preferably with a mechanical filtration and/or dewatering process c) calcium sulphate precipitate is obtained and separated, preferably with a mechanical filtration and/or dewatering process, by addition of sulfuric acid to the filtrate or supernatant d) the dissolved aluminium as aluminium hydroxophosphate precipitate is obtained and separated, preferably with a mechanical filtration and/or dewatering process, by raising the pH-value e) the filtrate or supernatant is optionally recycled for use in step a) f) the filtrate or the supernatant is optionally concentrated, preferably by evaporation, or g) calcium phosphate precipitate and calcium nitrate precipitate is optionally obtained and separated, preferably with a mechanical filtration and/or dewatering process, by addition of calcium oxide or calcium carbonate to the filtrate or supernatant. ### Claim 5 (depends on 2) Method according to claim 2 characterized in that the sulfuric acid is added in a dilution from 10 to 98 wt %, preferably 40 to 80 wt %, preferably in a stirred reactor, whereby the sulfuric acid is preferably added in a molar ratio, corresponding to the dissolved calcium concentration of 0.5 Ca to 1.5 SO4 (sulphate), preferably 1.0 Ca to 1.0 SO4 (sulphate). ### Claim 6 (depends on 3) Method according to claim 3 characterized in that the pH-value is adjusted to 2.0 to 3.0, preferably to 2.0 to 2.5, preferably with alkali or alkaline earth hydroxides or oxides, especially with caustic soda, caustic potash, sodium silicate solution, calcium hydroxide or calcium carbonate. ### Claim 7 (depends on 6) Method according to claim 6, characterized in that the phosphate-containing ash is obtained by incineration of phosphate-containing sewage sludges, biodegradable wastes, bio-wastes and/or animal wastes in a waste incineration plant. ### Claim 8 (depends on 1) Method according to claim 1 characterized in that the reaction of the solids is carried out with a mineral acid mixture, wherein said mineral acid mixture is present at a concentration of 5 wt % to 50 wt %, preferably 10 wt % to 30 wt % in aqueous dilution, and, optionally, the phosphate-containing ash is mixed in a reactor with the mineral acid mixture, wherein preferably the proportion of ash is 5 wt % to 50 wt %, preferably 20 wt % to 30 wt %, based on the diluted mineral acid mixture. ### Claim 9 (depends on 8) Method of claim 8, wherein the mineral acid mixture contains at least phosphoric acid (H3PO4) and nitric acid (HNO3), wherein the diluted mineral acid mixture contains preferably 10 wt % to 50 wt % HNO3, and 90 to 50 parts of H3PO4, based on the complete mineral acid content of the aqueous dilution. ### Claim 10 (depends on 2) Method according to claim 2 additionally comprising the obtaining (generation) of aluminium hydroxophosphate (Al(OH)3×AlPO4), characterized in that a) the solids (ash) are reacted with nitric acid or phosphoric acid or a mineral acid mixture of these two acids, b) the acid-insoluble portion of the solids is separated, c) calcium sulphate precipitate is optionally obtained and separated by adding sulphuric acid to the filtrate or supernatant, d) the dissolved aluminium as aluminium hydroxophosphate precipitate is obtained and separated by raising the pH-value, e) calcium phosphate precipitate and calcium nitrate precipitate is obtained and separated by addition of calcium oxide or calcium carbonate to the filtrate or supernatant. ### Claim 11 (depends on 2) Method according to claim 2 comprising the obtaining (generation) of precipitates selected from the group of calcium nitrate (CaNO3), calcium phosphate (Ca3(PO4)2), calcium sulphate (CaSO4), and aluminium hydroxophosphate (Al(OH)3×AlPO4); from phosphate-containing ashes from waste incineration plants, characterized in that a) the solids (ash) are reacted with nitric acid or phosphoric acid or a mineral acid mixture of these two acids, b) the acid-insoluble portion of the solids is separated, preferably with a mechanical filtration and/or dewatering process c) calcium sulphate precipitate is obtained and separated, preferably with a mechanical filtration and/or dewatering process, by addition of sulfuric acid to the filtrate or supernatant d) the dissolved aluminium as aluminium hydroxophosphate precipitate is obtained and separated, preferably with a mechanical filtration and/or dewatering process, by raising the pH-value e) the filtrate or supernatant is optionally recycled for use in step a) f) the filtrate or the supernatant is optionally concentrated, preferably by evaporation, or g) calcium phosphate precipitate and calcium nitrate precipitate is optionally obtained and separated, preferably with a mechanical filtration and/or dewatering process, by addition of calcium oxide or calcium carbonate to the filtrate or supernatant. ### Claim 12 (depends on 3) Method according to claim 3 comprising the obtaining (generation) of precipitates selected from the group of calcium nitrate (CaNO3), calcium phosphate (Ca3(PO4)2), calcium sulphate (CaSO4), and aluminium hydroxophosphate (Al(OH)3×AlPO4); from phosphate-containing ashes from waste incineration plants, characterized in that a) the solids (ash) are reacted with nitric acid or phosphoric acid or a mineral acid mixture of these two acids, b) the acid-insoluble portion of the solids is separated, preferably with a mechanical filtration and/or dewatering process c) calcium sulphate precipitate is obtained and separated, preferably with a mechanical filtration and/or dewatering process, by addition of sulfuric acid to the filtrate or supernatant d) the dissolved aluminium as aluminium hydroxophosphate precipitate is obtained and separated, preferably with a mechanical filtration and/or dewatering process, by raising the pH-value e) the filtrate or supernatant is optionally recycled for use in step a) f) the filtrate or the supernatant is optionally concentrated, preferably by evaporation, or g) calcium phosphate precipitate and calcium nitrate precipitate is optionally obtained and separated, preferably with a mechanical filtration and/or dewatering process, by addition of calcium oxide or calcium carbonate to the filtrate or supernatant. ### Claim 13 (depends on 3) Method according to claim 3 characterized in that the sulfuric acid is added in a dilution from 10 to 98 wt %, preferably 40 to 80 wt %, preferably in a stirred reactor, whereby the sulfuric acid is preferably added in a molar ratio, corresponding to the dissolved calcium concentration of 0.5 Ca to 1.5 SO4 (sulphate), preferably 1.0 Ca to 1.0 SO4 (sulphate). ### Claim 14 (depends on 4) Method according to claim 4 characterized in that the sulfuric acid is added in a dilution from 10 to 98 wt %, preferably 40 to 80 wt %, preferably in a stirred reactor, whereby the sulfuric acid is preferably added in a molar ratio, corresponding to the dissolved calcium concentration of 0.5 Ca to 1.5 SO4 (sulphate), preferably 1.0 Ca to 1.0 SO4 (sulphate). ### Claim 15 (depends on 4) Method according to claim 4 characterized in that the pH-value is adjusted to 2.0 to 3.0, preferably to 2.0 to 2.5, preferably with alkali or alkaline earth hydroxides or oxides, especially with caustic soda, caustic potash, sodium silicate solution, calcium hydroxide or calcium carbonate. ### Claim 16 (depends on 15) Method according to claim 15, characterized in that the phosphate-containing ash is obtained by incineration of phosphate-containing sewage sludges, biodegradable wastes, bio-wastes and/or animal wastes in a waste incineration plant. ### Claim 17 (depends on 2) Method according to claim 2 characterized in that the reaction of the solids is carried out with a mineral acid mixture, wherein said mineral acid mixture is present at a concentration of 5 wt % to 50 wt %, preferably 10 wt % to 30 wt % in aqueous dilution, and, optionally, the phosphate-containing ash is mixed in a reactor with the mineral acid mixture, wherein preferably the proportion of ash is 5 wt % to 50 wt %, preferably 20 wt % to 30 wt %, based on the diluted mineral acid mixture. ### Claim 18 (depends on 3) Method according to claim 3 characterized in that the reaction of the solids is carried out with a mineral acid mixture, wherein said mineral acid mixture is present at a concentration of 5 wt % to 50 wt %, preferably 10 wt % to 30 wt % in aqueous dilution, and, optionally, the phosphate-containing ash is mixed in a reactor with the mineral acid mixture, wherein preferably the proportion of ash is 5 wt % to 50 wt %, preferably 20 wt % to 30 wt %, based on the diluted mineral acid mixture. ### Claim 19 (depends on 4) Method according to claim 4 characterized in that the reaction of the solids is carried out with a mineral acid mixture, wherein said mineral acid mixture is present at a concentration of 5 wt % to 50 wt %, preferably 10 wt % to 30 wt % in aqueous dilution, and, optionally, the phosphate-containing ash is mixed in a reactor with the mineral acid mixture, wherein preferably the proportion of ash is 5 wt % to 50 wt %, preferably 20 wt % to 30 wt %, based on the diluted mineral acid mixture. ### Claim 20 (depends on 17) Method of claim 17, wherein the mineral acid mixture contains at least phosphoric acid (H3PO4) and nitric acid (HNO3), wherein the diluted mineral acid mixture contains preferably 10 wt % to 50 wt % HNO3, and 90 to 50 parts of H3PO4, based on the complete mineral acid content of the aqueous dilution.