Method for producing phosphoric acid
AssigneePrayon Technologies
InventorsAntoine Hoxha, Dorina Fati
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Abstract
The invention relates to a method for producing phosphoric acid, including: attacking phosphate rock by means of sulfuric acid between 70° and 90° C. with formation of a first calcium sulfate dihydrate crystal slurry, the aqueous acid phase of said slurry having free P2O5 content between 38 and 50 wt % and free SO3 content that is less than 0.5 wt % and greater than 0.05 wt %; converting said first slurry by means of heating at a temperature greater than 90° C., thus giving rise to a second slurry formed of calcium sulfate hemihydrate crystals; and, within the second slurry, separating a produced phosphoric acid, having a free SO3 content that is less than 2%, and a calcium sulfate hemihydrate filter cake.
Claims12
A method for producing phosphoric acid, comprising:
- an attack in an aqueous medium of phosphate rock by means of sulfuric acid at a first temperature comprised between 70 and 90° C., with formation of a first slurry of calcium sulfate dihydrate crystals suspended in an acid aqueous phase, the acid aqueous phase of this slurry having a free P2O5 content comprised between 38 and 50% by weight and a free SO3 content from 0.05 to 0.4% by weight,
- a conversion of this first slurry by heating to a temperature above 90° C., with solubilization of the calcium sulfate dihydrate crystals and recrystallization of the solubilized calcium sulfate giving rise to a second slurry formed of hemihydrate calcium sulfate crystals suspended in an aqueous phase based on phosphoric acid, and
- a separation in the second slurry between a production phosphoric acid, having a free SO3 content of less than 2% and greater than 0.05% by weight, and a P2O5 content from higher than 35% to 45% by weight, and a filtration cake based on calcium sulfate hemihydrate.
Dependencies are inferred from the claim text.