Oxidation treatment of carbon black

Claim 1

A NOVEL PROCESS FOR OXIDIZING CARBON BLACK WITH A NITROGENOUS OXIDIZING AGENT WHICH COMPRISES PROVIDING FIRST AND SECOND ENCLOSED ZONES IN OPEN COMMUNICATION WITH EACH OTHER, MAINTAINING SAID FIRST ZONE AT TEMPERATURES BETWEEN ABOUT 150*F. AND ABOUT 300*F. AND SAID SECOND ZONE AT TEMPERATURES BETWEEN ABOUT 250*F. AND ABOUT 400*F., CHARGING (A) CARBON BLACK INTO SAID FIRST ZONE HAD CONVEYING SAID BLACK FROM SAID FIRST ZONE INTO SAID SECOND ZONE, (B) A NITROGENOUS OXIDIZING AGENT CHOSEN FROM THE GROUP CONSISTING OF NITRIC ACIDS, NITROGEN OXIDES, AND MIXTURES THEREOF INTO EIGHTER ZONE, AND (C) A FREE OXYGEN-CONTAINING AS INTO THE DOWNSTREAM END OF SAID SECOND ZONE COUNTERCURRENT THE FLOW OF BLACK TO PROVIDE A SUBSTANTIALLY COMPLETE PURGE OF THE ENVIRONMENT ABOUT THE CARBON BLACK OUTLET FROM THE SECOND ZONE, SAID FREE OXYGEN-CONTAINING GAS BEING CHARGED IN AN AMOUNT SUFFICIENT TO PROVIDE AT LEAST A STOICHIOMETRIC SUFFICIENCY OF FREE OXYGEN TO CONVERT SUBSTANTIALLY ALL LOWER NITROGEN OXIDES TO NITROGEN DIOXIDE AND COLLECTING THE RESULTING BLACK PRODUCT AT THE DOWNSTREAM END OF SAID SECOND ZONE PROVIDED THAT THE TEMPERATURE IN THE SECOND ZONE IS HIGH ENOUGH TO CAUSE OXIDATION BY PRODUCTS AND REMAINING OXIDIZING AGENT TO BE DESORBED FROM THE BLACK.