Process for the production of isometric ferromagnetic gamma-ferric oxide

Claim 1

IN A PROCESS FOR THE PRODUCTION OF ISOMETIC CRYSTALS OF FERROMAGNETIC GAMMA-FERRIC OXIDE WHICH COMPRISES THE OXIDATION BY AIR OF A SUSPENSION OF PRECIPITATED FERROUS HYDROXIDE OBTAINED BY TREATMENT OF A SOLUTION OF FERROUS SALT WITH A BASE, AND SUBSEQUENTLY SEPARATING WASHING AND DRYING THE SAID OXIDEZED PRODUCT THE IMPROVEMENT WHICH COMPRISES PRECIPITATING THE FERROUS HYDROXIDE FROM A SOLUTION CONTAINING A FERROUS SALT HAVING A CONCENTRATION EQUIVALENT TO AN IRON CONTENT BETWEEN ABOUT 1 AND ABOUT 50 GRAMS PER LITER BY ADMIXING THE SAID FERROUS SALT SOLUTION WITH BETWEEN ABOUT 0.5 AND ABOUT 0.9 OF THE AMOUNT STOICHIOMETRICALLY EQUIVALENT TO THE IRON CONTENT OF THE SOLUTION OD A BASE OF THE GROUP CONSISTING OF AMMONIUM, ALKALI-METAL, AND ALKALINE-EARTH-METAL HYDROXIDES AND CARBONATES AT A TEMPERATURE BETWEEN ABOUT 0 AND ABOUT 35* C., AND THEREAFTER PASSING AIR THROUGH THE RESULTING FERROUS HYDROXIDE SUSPENSION AT A RATE BETWEEN ABOUT 1000 AND 50,000 LITERS PER HOUR PER LITER OF SUSPENSION UNTIL THE FERROUS HYDROXIDE IS CONVERTED TO FERRIC HYDROXIDE, AND SUBSEQUENTLY SEPARATING THE PRECIPITATED GRAMMA-FERRIC HYDROXIDE AND DEHYDRATING IT AT A TEMPERATURE BETWEEN ABOUT 200 AND ABOUT 300* C.