Method of treating furnace carbon black

Claim 1

A PROCESS FOR THE TREATMENT OF FURNANCE BLACKS WHICH COMPRISES UNIFORMLY HEATING A QUIESCENT, SHALLOW BED OF FURNACE BLACK, AND A THICKNESS NOT EXCEEDING ABOUT 1/4 INCH, TO BLACK-HEAT TEMPERATURE NOT LOWER THAN 650* F. BUT BELOW THE IGNITION TEMPERATURE OF THE PARTICULAR BLACK, NO PORTION OF THE BED OF BLACK BEING PERMITTED TO EXCEED A BLACK-HEAT TEMPERATURE, WHILE PASSING AIR OVER, AND IN CONTACT WITH, THE TREATMENT UNTIL THE SURFACE BLACK, AND CONTINUING THE TREATMENT UNTIL THE SURFACE AREA OF THE FURNACE BLACK PARTICLES HAS BEEN COMPLETELY OXIDIZED AS INDICATED BY THE MINIMUM PH CHARACTERISTIC WITHIN THE RANGE OF 2,5 TO 3.5, CONTINUING THE TREATMENT UNTIL AT LEAST 5%, BUT NOT IN EXCESS OF 75%, OF THE BLACK BY WEIGHT HAS BEEN CONSUMED WITHOUT IGNITION THEN SUBJECTING THE RESULTANT BLACK TO DEACTIVATION BY HEATING IN A NON-OXIDIZED ATMOSPHERE AT A TEMPERATURE WITHIN THE RANGE OF 1,800* TO 2,000* F. UNTIL A SUBSTANTIAL PROPORTION OF THE OXYGEN ABSORBED ON THE SURFACE OF THE CARBON DURING THE PRELIMINARY TREATMENT HAS BEEN DRIVEN OFF AND COOLING THE BLACK OUT OF CONTACT WITH FREE OXYGEN.