Method of heat hardening iron ore pellets containing fuel

Claim 1

A PROCESS FOR PRODUCING AN UNSINTERED MASS OF SEPARATE, INDIVIDUAL, SHOCK-RESISTANT, HEAT-HARDENED, IRON ORE PELLETS FROM GREEN, WATER-BOUND, IRON ORE PELLETS OF A SIZE RANGING SUBSTANTIALLY FROM ONE-QUARTER INCH TO THREEQUATER INCH, SAID PROCESS COMPRISING THE STEPS OF FORMING SAID GREEN WATER-BOUND PELLETS FROM FINELY DIVIDED CARBONACEOUS SOLID FUEL AND CONCENTRATED IRON ORE COMPRISING FINELY DIVIDED PARTICLES OF IRON OXIDE, SAID GREEN PELLETS CONTAINING SAID FUEL IN A QUANTITY TO PROVIDE FIXED CARBON IN THE AMOUNT OF 0.9 TO 2.4 PERCENT OF THE DRY WEIGHT OF SAID ORE; DEPOSITING SAID GREEN PELLETS UPON A MOVING GAS-PERMEABLE SUPPORT TO FORM A GENERALLY HORIZONTAL GAS-PERMEABLE LAYER IN WHICH SUBSTANTIALLY ALL OF SAID GREEN PELLETS RANGE IN SIZE FROM ONE-QUARTER INCH TO THREE-QUARTER INCH; MOVING SAID LAYER GENERALLY HORIZONTALLY THROUGH AN IGNITION CHAMBER WHILE DIRECTING A FLAME TRANSVERSELY INTO SAID LAYER TO ESTABLISH A BURNING ZONE IN WHICH THE CARBON CONTAINED IN THE PELLETS IN THE BURNING ZONE IS IGNITED AND THE PELLETS IN THE BURNING ZONE ARE HEATED TO A TEMPERATURE BETWEEN 2200* F. AND 2450* F.; AND MOVING SAID LAYER GENERALLY HORIZONTALLY OUT OF SAID IGNITION CHAMBER WHILE DIRECTING A FLOW OF AIR TRANSVERSELY THROUGH SAID LAYER TO MAINTAIN SAID BURNING ZONE IN AN OXIDIZING ATMOSPHERE AND TO MOVE SAID BURNING ZONE TRANSVERSELY THROUGH SAID LAYER FOR SUCCESSIVELY HEATING THE REMAINDER OF THE PELLETS IN SAID LAYER TO SAID TEMPERATURE IN SAID OXIDIZING ATMOSPHERE PROVIDED BY SAID AIR AS SAID BURNING ZONE TRANSVERSES SAID LAYER TO CAUSE ADHERENCE OF SAID FINELY DIVIDED PARTICLES IN EACH PELLET THROUGH DIFFUSION AND CRYSTAL GROWTH AND TO CAUSE EACH PELLET TO HARDEN NONFUSED TO ADJACENT PELLETS.