Process for preparation of titanium dioxide

Claim 1

A PROCESS FOR THE PREPARATION OF TITANIUM DIOXIDE WHICH COMPRISES; (1) REACTING AN ILMENITE ORE WITH SULFURIC ACID, (2) LEACHING THE ACIDULATED ORE TO REMOVE THE DISSOLVED TITANIUM VALUES THEREFROM, (3) REDUCING FERRIC IRON TO FERROUS IRONS, (4) EXTRACTING SAID TITANIUM VALUES FROM THE LEACH LIQUOR WITH AN EXTRACTANT MEMBER SELECTED FROM THE GROUP CONSISTING OF MONO- AND DIALKYL SUBSTITUTED ORTHOPHOSPHORIC ACIDS, EACH ALKYL GROUP OF SAID SUBSTITUTED ACID CONTAINING FROM 4 TO ABOUT 18 CARBONN ATOMS, (5) CONTAINING THE SUBSTANTIALLY IRON FREE EXTRACT WITH AN AQUEOUS SOLUTION TO STRIP THE TITANIUM VALUES THEREFROM, THE SOLUTE OF SAID SOLUTION BEING A MEMBER SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL HYDROXIDE, AMMONIUM HYDROXIDE, AMMONIUM CARBONATE, ALKALI METAL CARBONATE, A MIXTURE OF AMMONIUM HYDROXIDE AND AMMONIUM CARBONATE, HYDROGEN FLUORIDE, AMMONIUM FLUORIDE, AMMONIUM BIFLUORIDE, ALKALI METAL FLUORIDE AND ALKALI METAL BIFLUORIDE, (6) PRECIPITATING AND REMOVING THE TITANIUM VALUES FROM SAID AQUEOUS SOLUTION, (7) CONVERTING SAID TITANIUM VALUES TO THE HYDRATED TITANIUM OXIDE, AND (8) CALCINING THE PRECIPITATED HYDRATED TITANIUM OXIDE THEREBY PRODUCING SUBSTANTIALLY IRON-FREE ANHYDROUS TITANIUM DIOXIDE.