GB1301502A - - Google Patents

Abstract

1301502 Shaft furnaces K BECKENBACH 10 Dec 1970 [10 Dec 1969] 58790/70 Heading F4B [Also in Division C1] Magnesite, dolomite or other material to be calcined and sintered is fed to the top of a shift furnace, to be calcined in a zone A to which is fed hot gas from combustion chambers 12. The flow of material is restricted by a bridge 14 in a roasting zone B through which no gases flow. The bridge 14 has a recess 20 in its lower edge, Fig. 2, into which combustion chamber 22 delivers a fuel/air mixture which forms a downdraught gas current to sinter the material in zone C, additional fuel or air being supplied to the cavity 16 below the bridge by ducts 24. Exhaust gas from the sintering zone C, together with heated air from the updraught cooling zone D is fed to the upper combustion chambers 12 together with additional fuel and air. The air supplied to the lower combustion chamber 22 is preheated by the exhaust gases. The additional fuel or air for sintering may be fed to the furnace above the lower combustion chambers, and the composition of the gas delivered from the lower combustion chamber and the fuel or air supplied is regulated to give the required sintering temperature without damage to the furnace.