GB652138A - Improvements in rotary kilns - Google Patents

Abstract

652,138. Rotary kilns. INTERNATIONAL NICKEL CO. OF CANADA, Ltd. Sept. 30, 1948, No. 25518. Convention date, Jan. 12. [Class 51 (ii)l ] A rotary kiln through which the charge travels in countercurrent to combustion gases is characterized by a combustion chamber within the kiln in which fuel is burned out of contact with the charge material. As shown, the kiln 1 comprises a drying and heating zone Z-1, reduction zone Z-2 and cooling zone Z-3, ore being fed from the container B through the control gate C by screw conveyer 9. A burner 12 delivers into a combustion chamber 14 arranged at the discharge end of the kiln, combustion taking place out of contact with the ore which passes through the ports in the ring 18 to the cooling zone Z-3 formed by the annular water-cooled chamber surrounding the combustion chamber and from which the material is directed to the central discharge aperture 15 by the spiral blading 24. The ends of the kiln are supported by pivoted members 35 urged towards the kiln by springs 23, the discharge end being sealed by housing 21 and provided with sealing' rings 22, 22A and 32, 32A and a resilient packing ring 36 which provides pressure between the rings 32, 32A and also prevents escape of gas between the sealing ring 32A and sleeve 28 of the discharge housing. Combustion gases are prevented from entering the cooling chamber through the ported ring 18 by the introduction of a controlled atmosphere into the chamber at 19. The escape of waste gases to an offtake 7 is controlled by a damper 8 a supplementary air pipe 10 and conveyer 9 extending through the damper which is adjusted to maintain a positive gas pressure in the kiln in order to prevent infiltration of air. Heat transfer chains D and lifters 26 are provided. The sections of the kiln defining the zones Z-1 and Z-2 are lined with insulating brick 2, having an apparent specific gravity between 0.5 and 1.25.