Loading patent…
AssigneeGebr. Giulini GmbH
InventorsEgon Cherdron, Hans-Joachim Forster, Istvan Potencsik
Estimating the term…
In the manufacture of phosphoric acid by treatment of phosphate ores with excess phosphoric acid and precipitation of calcium ions as calcium sulfate, the purity and quality of the byproduct calcium sulfate is substantially improved by subjecting the monocalcium phosphate extract of the ore before precipitation of calcium sulfate to one or more preliminary treatments, whereby contaminent ions are substantially and preferentially removed from the extract while the calcium remains substantially in solution. These preliminary treatments may include separation of fluoride by reaction with silicon compounds, separation of radium by reaction with barium compounds in the presence of sulfate ions, and separation of strontium as strontium sulfate.
In the production of phosphoric acid by the digestion of calcium-containing phosphate ore with phosphoric acid thereby producing a mono-calcium phosphate/phosphoric acid solution and the mono-calcium phosphate in said solution is reacted with sulfuric acid with the formation of phosphoric acid and a precipitate of calcium sulfate, the improvement which comprises treating the mono-calcium phosphate-containing solution with at least one soluble barium compound in the presence of sulfate ions to precipitate therefrom contaminant radium ions which would otherwise be precipitated with said calcium sulfate, removing the resulting precipitate while retaining the mono-calcium phosphate in solution and thereafter adding sulfuric acid to the thus-purified solution to produce phosphoric acid and a precipitate of high-purity calcium sulfate.
Dependencies are inferred from the claim text.