Preparation of brown oxide of iron

Claim 1

THE PROCESS OF MANUFACTURING BROWN OXIDE OF IRON PIGMENTS, WHICH COMPRISES FORMING A SLURRY OF RED HYDROUS FERRIC OXIDE NUCLEI BY TREATING AN AQUEOUS SLURRY OF FERROUS SALT WITH AN EXCESS OF ALKALI UNDER OXIDIZING CONDITIONS TO FORM A SLURRY OF COLLOIDAL PARTICLES OF HYDROUS FERRIC OXIDE NUCLEI, ADDING A FERROUS SALT TO THE RESULTANT SLURRY TO REACT WITH THE UNREACTED ALKALI WHILE SUBJECTING THE RESULTANT REACTION MIXTURE TO OXIDATION, THEREAFTER ADDING METALLIC IRON SCRAP TO THE RESULTANT SLURRY WHILE SUBJECTING IT TO OXIDIZING CONDITIONS UNTIL A SLURRY OF RED HYDROUS FERRIC OXIDE OF DESIRED PARTICLE SIZE AND SHADE IS OBTAINED, AND PRECIPITATING ON THE RED HYDROUS FERRIC OXIDE PARTICLES OF SAID SLURRY FROM 5% TO 30% BY WEIGHT, BASED ON THE WEIGHT OF THE PIGMENTS, OF FERROUS OXIDE PRODUCED BY REACTING A FERROUS SALT WITH SMALL EXCESS OF ALKALI IN THE PRESENCE OF SAID SLURRY AND IN THE ABSENCE OF OXIDIZING AGENT, THUS PRODUCING THE DESIRED BROWN OXIDE OF IRON PIGMENTS.