Plasma heated furnace for iron ore pellet induration

Abstract

In the present pelletizing apparatus, the induration of iron ore concentrate pellets is achieved in a tunnel furnace heated by plasma torches, wherein the generation of CO2 by the conventional iron ore pelletizing processes is reduced by using electricity powered plasma torches instead of burning natural gas, heavy oil or pulverized coal in burners, thereby reducing considerably industrial pollution of the atmosphere.

1 . A pelletizing apparatus, comprising a firing chamber, a traveling grate for sequentially transporting ore pellets in drying, firing and cooling zones, and at least one plasma torch for providing a heat required for indurating the ore pellets in the firing chamber. 
     
     
         2 . The pelletizing apparatus according to  claim 1 , wherein means are provided for conveying air heated by the plasma torch to the drying zone for drying green pellets located upstream of the firing zone. 
     
     
         3 . The pelletizing apparatus according to  claim 1 , wherein means are provided for introducing air recuperated from the pellet cooling zone in at least one chamber, where it is mixed with the extremely hot air from the plasma torch, prior to entering the pellet firing chamber. 
     
     
         4 . The pelletizing apparatus according to  claim 1 , wherein there are provided two plasma torches. 
     
     
         5 . A pelletizing method, wherein ore pellets are fed sequentially through drying, firing and cooling zones, and wherein heat required for the process is provided by at least one plasma torch. 
     
     
         6 . The pelletizing method according to  claim 5 , wherein the ore pellets are transported by a traveling grate through the drying, firing and cooling zones. 
     
     
         7 . The pelletizing method according to  claim 5 , wherein recuperated air from the cooling zone is introduced in at least one chamber, where it is mixed with the extremely hot air from the plasma torch, prior to entering the pellet firing chamber. 
     
     
         8 . The pelletizing method according to  claim 5 , wherein air heated by the plasma torch is used in the drying zone for drying green pellets located upstream of the firing zone. 
     
     
         9 . A firing device in a pelletizing apparatus, comprising a firing chamber for ore pellets being transported through the pelletizing apparatus, and at least one plasma torch for providing a heat required for indurating the ore pellets in the firing chamber. 
     
     
         10 . The firing device according to  claim 9 , wherein at least one conduit is provided to convey hot air from a cooling zone of the pelletizing apparatus to the plasma torch, where the hot air from a cooling zone is mixed with very hot air heated by the plasma torch, a resulting hot air mixture being directed to the firing chamber. 
     
     
         11 . The firing device according to  claim 9 , wherein there are provided two plasma torches, each being fed via conduits with hot air from the cooling zone. 
     
     
         12 . The firing device according to  claim 11 , wherein a common main conduit is provided for conveying hot air from the cooling zone to the at least one conduit associated with each plasma torch. 
     
     
         13 . A plasma torch for use in a firing device of an iron ore pelletizing apparatus, comprising at least two electrodes, namely one cathode and one anode, an electric arc being sustained between the two electrodes, a vortex ring for injecting compressed gas, such as air, between the two electrodes and for spinning the gas at high speed, an electrical insulator placed between the two electrodes, a jet of hot plasma gas exiting the torch for use in heating air before it reaches a firing chamber of the firing device. 
     
     
         14 . The plasma torch according to  claim 13 , wherein multiple anodes and vortexes are used to increase arc length and volume of hot gas. 
     
     
         15 . The plasma torch according to  claim 13 , wherein internal parts of the torch are mounted inside a water cooled shell for keeping the electrodes cool relative to the hot process environment. 
     
     
         16 . The pelletizing apparatus according to  claim 2 , wherein means are provided for introducing air recuperated from the pellet cooling zone in at least one chamber, where it is mixed with the extremely hot air from the plasma torch, prior to entering the pellet firing chamber. 
     
     
         17 . The pelletizing apparatus according to  claim 2 , wherein there are provided two plasma torches. 
     
     
         18 . The pelletizing apparatus according to  claim 3 , wherein there are provided two plasma torches. 
     
     
         19 . The pelletizing method according to  claim 6 , wherein recuperated air from the cooling zone is introduced in at least one chamber, where it is mixed with the extremely hot air from the plasma torch, prior to entering the pellet firing chamber. 
     
     
         20 . The firing device according to  claim 10 , wherein there are provided two plasma torches, each being fed via conduits with hot air from the cooling zone.