Process for heat-treating solids

Claim 1

PROCESS OF INDURATING CONSOLIDATED MASSES, SUCH AS BRIQUETS, SPHERES, PELLETS, OR THE LIKE, CONSISTING OF MOIST OXIDIC IRON ORE FINES AND SIMILAR FINELY DIVIDED METALLURGICAL MATERIALS PREPARATORY TO REDUCTION OF THE IRON OXIDES IN A REDUCTION FURNACE SUCH AS A BLAST FURNACE, INVOLVING HEATING SUCH PELLETS TO AN ELEVATED TEMPERATURE AT WHICH INDURATION OF THE PELLETS OCCURS, WHICH COMPRISES ESTABLISHING TWO SUBSTANTIALLY VERTICAL GAS-TRAVERSABLE COLUMNS OF PREVIOUSLY INDURATED PELLETS WHICH COLUMNS ARE RELATIVELY SHALLOW WITH RESPECT TO THEIR CROSS-SECTIONAL AREA, MAINTAINING AT LEAST THE TOP PORTION OF AT LEAST ONE OF SAID COLUMNS, CALLED THE FIRST COLUMN, AT SUBSTANTIALLY INDURATING TEMPERATURE, PERIODICALLY ADDING A LAYER OF RAW MOIST PELLETS TO THE TOP OF THE OTHER COLUMN, CALLED THE SECOND COLUMN, SAID LAYER BEING LIMITED IN VERTICAL HEIGHT SO AS TO AVOID CRUSHING THEREIN, PASSING A CURRENT OF AIR UPWARDLY THROUGH AT LEAST THE UPPER PORTION OF THE FIRST COLUMN WHEREBY TO TRANSFER HEAT FROM HOT PELLETS THEREIN TO THE AIR CURRENT, BURNING A FUEL IN THE SO-PREHEATED AIR, AFTER THE SAME HAS TRAVERSED SAID FIRST COLUMN, IN QUANTITY SUFICIENT TO RAISE THE TEMPERATURE OF THE AIR TO INDURATING TEMPERATURE, PASSING THE SO-HEATED AIR AND PRODUCTS OF SUCH COMBUSTION DOWNWARDLY THROUGH AT LEAST THE UPPER PORTION OF THE SECOND COLUMN, IN THE RATIO OF FROM ABOUT 8 TO ABOUT 15 CUBIC FEET OF THE HEATING GAS PER EACH 1 POUND OF INITIALLY RAW MOIST PELLETS IN SAID LAYER, WHEREBY PROMPTLY TO RAISE THE TEMPERATURE OF THE FRESHLY CHARGED LAYER OF INITIALLY RAW MOIST PELLETS THEREIN BY HEAT TRANSFER FROM THE HEATED GASEOUS CURRENT TO AND THROUGH THE WATER-VAPORIZING TEMPERATURE TO INDURATING TEMPEATURE, EXHAUSTING THE RESULTING COOLED GAS TO ATMOSPHERE, TERMINATING THE PASSAGE OF GAS SERIALLY THROUGH SAID FIRST AND SEOCND COLUMNS BEFORE THE BOTTOM PORTION OF THE SECOND COLUMN HAS BECOME MATERIALLY HEATED, REMOVING A LAYER, OF LIMITED THICKNESS OF INDURATED AND COOLED PELLETS FROM THE BOTTOM OF SAID FIRST COLUMN AND ADDING A LIKE VOLUME OF RAW MOIST PELLETS TO THE TOP OF SAID FIRST COLUMN, PASSING A CURRENTOF AIR UPWARDLY THROUGH AT LEAST THE UPPER PORTION OF SAID SECOND COLUMN, BURNING A FUEL IN THE SO-PREHEATED AIR CURRENT, AFTER THE SAME HAS TRAVERSED SAID SECOND COLUMN, IN QUANTITY SUFFICIENT TO RAISE ITS TEMPERATURE TO INDURATING TEMPERATURE, PASSING THE SO-HEATED CURRENT OF GAS DOWNWARDLY THROUGH AT LEAST THE UPPER PORTION OF SAID FIRST COLUMN, IN THE RATIO OF FROM ABOUT 8 TO ABOUT 15 CUBIC FEET OF THE HEATING GAS PER EACH 1 POUND OF INITIALLY RAW MOIST PELLETS IN THE LAYER SO ADDED, WHEREBY PROMPTLY TO RAISE THE TEMPERATURE OF THE TOP LAYER OF INITIALLY RAW MOIST PELLETS THEREIN BY HEAT TRANSFER FROM SAID HEATED GASEOUS CURRENT TO AND THROUGH THE WATER-VAPORIZING TEMPERATURE AND TO INDURATING TEMPERATURE, EXHAUSTING THE RESULTING COOLED GAS TO ATMOSPHERE, TERMINATING THE PASSAGE OF GAS SERIALLY THROUGH SAID SECOND AND FIRST COLUMNS BEFORE THE BOTTOM PORTION OF SAID FIRST COLUMN HAS BECOME MATERIALLY HEATED, AND REPEATING THE ALTERNATION OF STEPS.