Production of dead burned magnesia in a shaft kiln

Claim 1

THAT METHOD OF MAKING DEAD BURNED BASIC REFRACTORY GRAIN COMPRISING THE STEPS OF: (1) CONTINUOUSLY PASSING A CHARGE OF BRIQUETTES OF AT LEAST ONE MATERIAL OF THE GROUP CONSISTING OF MAGNESIA, DOLOMITE AND LIME INTO THE UPPER END OF A VERTICLE SHAFT KILN FOR MOVEMENT TO THE LOWER END OF THE KILN; (2) SUPPLYING SUFFICIENT HEAT AT AN INTERMEDIATE ZONE OF THE KILN TO HEAT THE BRIQUETTES IN THAT ZONE TO A DEAD BURNING TEMPERATURE OF AT LEAST ABOUT 3000*F.; (3) PASSING AIR UPWARDLY THROUGH A LOWER PORTION OF THE KILN COUNTERCURRENT TO THE DOWNWARDLY MOVING CHARGE OF BRIQUETTES; (4) CONTROLLING THE AIR FLOW SO THE DOWNWARDLY MOVING BRIQUETTES, FROM THEIR ENTRY TO THE KILN UNTIL THEY REACH A TEMPERATURE OF ABOUT 2000*F. ARE HEATED AT A RATE NOT EXCEEDING ABOUT 200*F. PER MINUTE; (5) SUBSEQUENTLY SUBJECTING THE 2000*F. BRIQUETTES TO DEAD BURNING; AND (6) CONTINUOUSLY WITHDRAWING DEAD BURNED BRIQUETTES FROM THE LOWER END OF THE KILN.