Method for the alkaline roasting of an acidic oxide ore

Claim 1

IN THE ALKALINE ROASTING OF AN ACIDIC OXIDE ORE, THE STEP OF ROASTING A MIXTURE OF THE ORE WITH AN ALKALI METAL CARBONATE AND A MATERIAL FOR RE ACTING WITH SAID CARBONATE TO FORM ALKALI METAL HYDROXIDE UNDER THE CONDITIONS OF THE ROAST AT A TEMPERATURE BETWEEN 300* AND BELOW ABOUT 850* C., AND SUPPLYING OXYGEN TO THE ROAST IN A QUANTITY BETWEEN ABOUT FOUR TIMES AND LESS THAN ABOUT TEN TIMES THAT REQUIRED STOICHIOMETRICALLY TO FORM AN ALKALI METAL SALT WITH THE ACIDIC OXIDE UNDER THE CONDITIONS OF THE ROAST, THE QUANTITY OF SAID ALKALI METAL CARBONATE PRESENT IN THE MIXTURE WITH THE ORE BEING SUBSTANTIALLY EQUIVALENT TO THAT REQUIRED STOICHIOMETRICALLY TO COMBINE AS NORMAL ALKALI SALT WITH THE TOTAL CONTENT OF ALL ACIDIC OXIDES PRESENT IN THE ORE, THE MATERIAL BEING SELECTED FROM THE GROUP CONSISTING OF WATER AND ALKALINE EARTH HYDROXIDES, THE QUANTITY OFTHE MATERIAL BEING SUFFICIENT THEORETICALLY TO INDUCE SUBSTANTIALLY COMPLETE CONVERSION OF THE ALKALI METAL CARBONATE PRESENT TO ALKALI METAL HYDROXIDE.