Production of Phosphate Compounds from Materials Containing Phosphorus and at Least One of Iron and Aluminium
AssigneeEasymining Sweden AB
InventorsYariv COHEN, Patrik ENFÄLT
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Abstract
A method for production of phosphate compounds comprises dissolving of a raw material comprising phosphorus, aluminium and iron, in a mineral acid. Insoluble residues from the dissolving step are separated. Iron hydroxide is added causing precipitation of phosphate compounds. The precipitated phosphate compounds are removed. The phosphate compounds are dissolved by an alkaline solution. Iron hydroxide is filtered out. Lime is added, causing precipitation of calcium phosphate. The precipitated calcium phosphate is separated. The leach solution after the separating of precipitated calcium phosphate is recycled to be used for dissolving phosphate compounds by an alkaline solution.
Claims12
A method for the production of phosphate compounds, comprising the steps of:
- dissolving a raw material comprising sludge ash, comprising phosphorus, aluminium and iron, in a liquid comprising at least mineral acid;
- separating insoluble residues from said dissolving step, thereby forming a primary leach solution;
- adding a base comprising iron hydroxide to said primary leach solution, after said step of separating insoluble residues, causing precipitation of phosphate compounds comprising iron and aluminium from said primary leach solution;
- removing said precipitated phosphate compounds from said primary leach solution;
- dissolving said phosphate compounds by an alkaline solution into a second leach solution;
- filtering iron hydroxide from said second leach solution;
- adding lime into said second leach solution after said step of filtering iron hydroxide, causing precipitation of calcium phosphate;
- separating precipitated calcium phosphate from said leach solution;
- recycling said leach solution after said step of separating precipitated calcium phosphate to be used in said step of dissolving phosphate compounds by an alkaline solution.
A system for production of phosphate compounds, comprising:
- an ash leaching reactor, having an inlet for receiving raw material comprising a sludge ash comprising phosphorus, aluminium and iron and an inlet for dissolving acid comprising mineral acid;
- said ash leaching reactor being arranged for dissolving said raw material in said mineral acid;
- a residue separator connected to an outlet of said ash leaching reactor and arranged for separating insoluble residues from said ash leaching reactor, thereby forming a primary leach solution;
- a base mixing arrangement connected after an outlet from said residue separator and arranged for adding a base comprising at least iron hydroxide to said primary leach solution through an inlet;
- a phosphate separator connected to an outlet of said base mixing arrangement and arranged for removing precipitated phosphate compounds from said primary leach solution through a precipitated phosphate compound outlet;
- said phosphate separator having an outlet through which remaining said primary leach solution exits;
- a dissolution reactor arranged for dissolving said precipitated phosphate compounds in an alkaline solution into a second leach solution;
- a first solid/liquid separator connected to said dissolution reactor and arranged for separating residue from said second leach solution;
- a mixing volume connected to said first solid/liquid separator and arranged for adding lime into said second leach solution causing precipitation of calcium phosphate;
- a second solid/liquid separator connected to said mixing volume and arranged for separating said calcium phosphate precipitated in said mixing volume from said second leach solution;
- and
- a recycling arrangement connected between said mixing volume and said dissolution reactor and arranged for recycling at least a part of said second leach solution after said second solid/liquid separator to be used in said dissolution reactor as at least a part of said alkaline solution.
Dependencies are inferred from the claim text.