Abstract:
A smelting reduction apparatus which separates exhaust gas, which is exhausted from a melter-gasifier or a fluidized bed reactor, into dusts and reducing gas to supply them to each fluidized bed reactor respectively is disclosed, in which the smelting reduction apparatus includes a three-stage type fluidized bed reactor, a melter-gasifier for manufacturing molten pig iron by finally reducing the fine iron ores of which reaction is finished in a final fluidized bed reactor, and a dust separating device, which performs separation of exhausted gas from the melter-gasifier into dusts and reducing gas, so as to supply the separated reducing gas to a lower part of the final fluidized bed reactor, dusts having a larger particle sizes in the separated dusts to the melter-gasifier again, and fine dusts having a smaller particle sizes in the separated dusts to an upper part of a gas distributor of the final fluidized bed reactor.

Description:
BACKGROUND OF THE INVENTION 
     a) Field of the Invention 
     The present invention relates to smelting reduction process and, more particularly, to a smelting reduction apparatus which separates exhaust gas, which is exhausted from a melter-gasifier or a fluidized bed reactor, into dusts and reducing gas to supply them to a corresponding fluidized bed reactor respectively. 
     (b) Description of the Related Art 
     Generally, a blast furnace has been extensively used to make iron through reducing and melting iron ores. However, the blast furnace involves a drawback that the charging materials should be pre-treated to bear is agglomerated forms such as sintered iron ores and cokes. 
     In order to solve such a problem, a smelting and reduction process has been developed for the direct use of fine iron ores and coal without pretreatment. 
     The smelting reduction process is composed of a preliminary reduction process and a final reduction process. In the preliminary reduction process, the charged fine iron ores are pre-heated and then preliminarily reduced. In the final reduction process, a sponge iron which is reduced in the preliminary reduction process is finally reduced and melted in the presence of high pressure oxygen and coal to thereby form a molten iron. 
     The fluidized bed reduction reactor (hereinafter, referred to “fluidized bed reactor”) is used as an equipment for the preliminary reduction process, and a melter-gasifier is used as an equipment for the final reduction process. 
     The preliminary reduction process is typically divided into a moving bed type and a fluidized bed type according to a contact state between raw iron ores and reducing gas. It is efficient to apply the fluidized bed type preliminary reduction process rather than the moving bed type if the charged iron ore has a small particle size and a wide particle size distribution. 
     Korean Patent No. 117065 discloses an apparatus for such a fluidized bed type preliminary reduction process. According to this patent, a device for uniformly reducing a fine iron ore having a wide particle size distribution in a fluidized bed reactor is proposed. In order to achieve such a uniform reducing of the fine iron ore, the patent provides a three-stage type fluidized reactor which is designed in a conical shape having a wide upper part and a narrow lower part, wherein the iron ore is reduced through three stages of pre-heating, pre-reducing and final preliminary reducing. This patent also proposes a cyclone for collecting fine iron ore, which is discharged, from an upper part of the respective fluidized bed reactors by scattering to supply to a bottom part of the respective fluidized bed reactors. 
     According to this patent designed as above, the fine iron ore having the wide particle size distribution may be efficiently reduced while maintaining stable fluidized state. 
     This patent has, however, a disadvantage that a gas distributor of the fluidized bed reactors may be clogged by dusts dust contained in the reducing gas. That is, a large amount of dusts is included in exhaust gas, which is discharged from the melter-gasifier and supplied to the fluidized bed reactors. If the dusts are supplied to the gas distributor of a final reduction furnace, the dust becomes stuck to nozzles, which are mounted in the gas distributor, and if the sticking phenomenon is accumulated, the gas distributor itself becomes clogged. 
     If the gas distributor is clogged as above, it becomes impossible to maintain a uniform flow of the reducing gas in the fluidized bed reactors, and more severely, operations should be stopped. 
     SUMMARY OF THE INVENTION 
     Therefore, the present invention is derived to resolve the above disadvantages and problems of the related art and has an object to provide a smelting and reduction apparatus which can separate exhaust gas, which is exhausted from a melter-gasifier or a fluidized bed reactor, into dusts and reducing gas to supply them to each fluidized bed reactor respectively. 
     It is another object of the present invention to provide a method for manufacturing molten pig iron by a smelting and reduction process, which can prevent sticking of particles of fine iron ores and clogging of a gas distributor by coating separated dusts on a surface of the particles of the fine iron ores which is flowing in the fluidized bed reactors. 
     This and other objects may be achieved by the present invention, which is described in detail hereinafter. 
     According to one aspect of the present invention, a smelting and reduction apparatus includes a three-stage type fluidized reactor, a melter-gasifier for manufacturing molten pig iron by finally reducing fine iron ores of which reaction is finished in a final fluidized reactor, and a dust separating device, which performs separation of exhausted gas from the melter-gasifier into dusts and reducing gas so as to supply the separated reducing gas to a lower part of the final fluidized bed reactor, dusts having a larger particle sizes in the separated dusts to the melter-gasifier again, and fine dusts having a smaller particle sizes in the separated dusts to an upper part of a gas distributor of the final fluidized bed reactor. 
     The three-stage type fluidized bed reactor of the present invention includes a) an or e charging duct mounted on a side of respective fluidized bed reactors for charging fine iron ores, b) a gas supply duct mounted at a lower part of the respective fluidized bed reactors, c) an ore discharge duct mounted on a side wall of the respective fluidized bed reactors for discharging fine iron ores which are charged into the respective fluidized bed reactors and reactions thereof are finished, d) a gas distributor mounted in the respective fluidized bed reactors for uniformly dispersing reducing gas into the respective fluidized bed reactors, and e) a cyclone for separating fine iron ore particles from the reducing gas, which is discharged from the upper parts of the respective fluidized bed reactors, to supply the reducing gas to next reactor or discharge outside and recycle the fine iron ore particles to the lower parts of the respective fluidized bed reactors. 
     In the present invention, each fludized bed reactor is manufactured in a dual-stage cylindrical shape of which a diameter of a lower part is small and a diameter of an upper part is large so that lower and the upper parts are to connected to each other slantingly. In the dual-stage cylindrical fluidized bed reactors, the diameter of the upper cylindrical part is larger than that of the lower cylindrical part by 1.5˜2.0 times, and the inclination of the connection between the upper and lower cylindrical parts is 20˜30° with relation to a central axis of the fluidized bed reactors. A whole height of the fluidized bed reactors is larger than a diameter of the lower cylindrical part by 10˜20 times. 
     In the present invention, the dust separation device is formed of at least two or more cyclones and at least one or more dust storage bins. A first cyclone of the cyclones is connected to the upper part and the lower part of the melter-gasifier and an upper part of a second cyclone. The second cyclone is connected to the lower part of the final fluidized bed reactor and an upper part of the dust storage bin and the dust storage bin is connected to an upper part of the gas distributor of the final fluidized bed reactor. 
     In the dust separation device, the second cyclone and the dust storage bin is connected by a dust supply duct which is mounted with a two-way valve, wherein the dust supply duct branched by the two-way valve is connected to a dust supply duct which connects the first cyclone and the melter-gasifier. 
     The dust storage bin part is formed of three dust storage bins respectively connected to one another via the dust supply ducts. The dust supply duct which is positioned at a lower part of a first dust storage bin is mounted with a nitrogen gas injection device, so that dusts stored in the first dust storage bin can be pneumatically transported to a second dust storage bin with high pressure nitrogen gas. A dust supply duct which is positioned at a lower part of a third dust storage bin is also mounted with a nitrogen gas injection device, so that the dusts stored in the third dust storage bin can be introduced into the final reactor with high pressure nitrogen gas. 
     On the other hand, a dust supply duct connecting the lower part of the third dust storage bin to the nitrogen gas injection device is mounted with a dust introducing feeder for controlling the amount of dust supply to the final reactor. Further, each of the dust supply ducts is mounted with a control valve for controlling a supply of the dusts conveyed to the dust supply ducts. 
     The molten pig iron is manufactured from the fine iron ores by using the smelting reduction apparatus hereinabove. 
     The process for manufacturing the molten pig iron by using the smelting reduction apparatus of the present invention is characterized in that the exhaust is gas discharged from the melter-gasifier is separated into reducing gas and dusts to be supplied to the final fluidized bed reactor. 
     Even though the separated reducing gas is directly supplied to the lower part of the final fluidized bed reactor, the dusts are separated again such that the fine dusts having a smaller particle size is blown into the upper part of the gas distributor of the final fluidized bed reactor by high pressure nitrogen. 
     As the fine dusts are blown into the fluidized bed reactor, the fine dusts are coated on surfaces of the fine iron ores, so that the sticking between the fine iron ores and the gas distributor may be prevented. 
     The pressure of the nitrogen for the injection of dust particles is controlled higher than an internal pressure of the final fluidizing bed reactor by 2˜3 times. 
     A velocity of the reducing gas in the respective fluidizing bed reactors is preferably controlled 1.2˜1.5 times of a minimum fluidizing velocity of the fine iron ores residing in the fluidizing bed reactors. 
     If the molten pig iron is manufactured by the process described hereinabove, the sticking between the fine iron ores and the gas distributor may be prevented, thereby effectively preventing operation obstacles of the smelting reduction process. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawing, in which like reference symbols indicate the same or the similar components, wherein: 
     FIG. 1 is a structural view of a smelting reduction apparatus including a three-stage type fluidized bed reactor according to a preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of this invention will be explained with reference to the accompanying drawing. 
     FIG. 1 illustrates a structural view of a smelting reduction apparatus including three-stage type fluidized bed reactors. 
     As shown in FIG. 1, the smelting reduction apparatus includes a three-stage type fluidized bed reactor and a melter-gasifier  40 . 
     The three-stage type fluidized bed reactors include a pre-heating furnace  10 , a pre-reducing furnace  20 , and a final reducing furnace  30 . 
     The pre-heating furnace  10  is mounted with an ore charging duct  1  on a side wall for charging fine iron ores which fall down from a charging bin  5 , a gas supply duct  28  at a lower part for supplying reducing gas which is discharged from the pre-reducing furnace  20 , and a first cyclone  15  at an upper part. The first cyclone  15  collects fine particles of ores which are included in the exhaust gas discharged via a gas discharging duct  13  and re-supplies the fine ore particles to the lower part of the pre-heating furnace  10 . The exhaust gas from which the fine ore particles are removed is released outside via a discharge duct  16 , which is mounted at an upper part of the cyclone  15 . 
     The pre-reducing furnace  20  is mounted with an ore discharging duct  11  on a side wall for supplying the fine iron ores which are preheated in the pre-heating furnace  10 , a gas supply duct  38  at a lower part for supply reducing gas which is discharged from the final reducing furnace  30 , and a second cyclone  25  at an upper part. The second cyclone  25  collects fine particles of ores which are included in the exhaust gas discharged via a gas discharging duct  23  and re-supplies the fine ore particles to a lower part of the pre-reducing furnace  20 . The exhaust gas from which the fine ore particles are removed is supplied to the lower part of the pre-heating furnace  10  via a gas supply duct  28  which is mounted at an upper part of the cyclone  25 . 
     The final reducing furnace  30  is mounted with an ore discharging duct  21  on a side wall for supplying the fine iron ores which are pre-reduced in the pre-reducing furnace  20 , a gas supply duct  58  at a lower part for supply reducing gas which is discharged from the melter-gasifier  40 , and a third cyclone  35  at an upper part. The third cyclone  35  collects fine particles of ores which are included in the exhaust gas discharged via a gas discharging duct  33  and re-supplies the fine ore particles to a lower part of the final reducing furnace  30 . The exhaust gas from which the fine ore particles are removed is supplied to the lower part of the pre-reducing furnace  20  via a gas supply duct  38  which is mounted at an upper part of the cyclone  35 . 
     As for the shape of the respective fluidized bed reactors as described above, the pre-heating furnace  10 , the pre-reducing reactor  20  and the final reducing reactor  30  has a small diameter in the lower parts  10   a ,  20   a , and  30   a , a large diameter in the upper parts  10   b ,  20   b , and  30   b , and the slantingly formed cylindrical connection parts  10   c ,  20   c , and  30   c . Therefore, the whole shape of the respective fluidized bed reactors is formed in the dual-stage cylinder having the narrow lower parts and the wide upper parts. 
     The diameter of the upper parts  10   b ,  20   b  and  30   b  of the respective fluidized bed reactors is formed in the range of 1.5˜2.0 times of the diameter of the lower parts  10   a ,  20   a  and  30   a,  such that the velocity of the gas in the upper parts of the respective fluidized bed reactors is decreased for preventing the fine iron ores from being discharged as they are. 
     The whole height of the respective fluidized bed reactors is preferably formed 10˜20 times of the diameter of the lower parts  10   a ,  20   a  and  30   a . If the respective fluidized bed reactors are formed in the elongated dual-stage cylindrical shape, a space in which the fine iron ores flow is sufficiently assured and the fine iron ores are prevented from being discharged as they are. Further, height of the cylindrical lower parts  10   a ,  20   a  and  30   a  is preferably formed in 1.0˜1.5 times of height of the cylindrical upper parts  10   b ,  20   b  and  30   b , and the inclination of the connecting parts  10   c ,  20   c  and  30   c  is preferably formed inclined by 20˜30° with relation to the central axes of the respective fluidized bed reactors. 
     The fine iron ores which are preliminary reduced in the final reducing furnace  30  of the three-stage type fluidized bed reactors as above, are supplied to the upper part of the melter-gasifier  40  which will be described hereinafter via an ore discharging duct  31 . The exhaust gas, which is discharged from the melter-gasifier  40 , is, however, not directly supplied to the final reducing furnace  30  but via the dust separation device, which will be described hereinafter. 
     The dust separation device according to the present invention is mounted between the melter-gasifier  40  and the final reducing furnace  30  and includes two cyclones and three dust storage bins which are disposed in series. 
     Now, the dust separation device will be described in more detail. 
     First, a fourth cyclone  45 , which is a first element of the dust separation device, is connected to the melter-gasifier  40 , through an exhaust gas discharging duct  43  and a first dust supply duct  46 . The fourth cyclone  45  is supplied with high temperature exhaust gas from the melter-gasifier  40  via the exhaust gas discharging duct  43  and primarily separate dusts which are included in the exhaust gas to collect. The dusts collected by the fourth cyclone  45  are supplied to the melter-gasifier  40  via the first dust supply duct  46 . Reducing gas from which the dusts are primarily removed in the fourth cyclone  45  is supplied to a fifth cyclone  50  which will be described hereinafter via an exhaust gas discharging duct  47  which is mounted at an upper part of the fourth cyclone  45 . 
     The fifth cyclone  50  separates and collects dusts of an ultra fine particle shape which are included in the reducing gas which is supplied from the fourth cyclone  45  but not separated by the fourth cyclone  45 . The ultra fine dusts collected by the fifth cyclone  50  are supplied to a first dust storage bin  60  via a second dust supply duct  51  which is connected to a lower part of the fifth cyclone  50 , wherein the second dust supply duct  51  is mounted with a two-way valve  52  so that the dusts collected in the fifth cyclone  50  are partially re-supplied to the melter-gasifier  40  via a third dust supply duct  57  as necessary. The third dust supply duct  57  may be directly connected to the melter-gasifier  40  and is more preferably connected to the first dust supply duct  46 . 
     The fifth cyclone  50  is connected to a reducing gas discharge duct  58  at an upper part to supply the reducing gas from which the dusts are removed to the final reducing furnace  30 . 
     The first dust storage bin  60  is mounted with a first nitrogen injection device N 1  at a lower part for conveying the stored ultra fine dusts to a second dust storage bin  70 . The first dust storage bin  60  is connected to the dust storage bin  70  via a dust conveying duct  61 . 
     The second dust storage bin  70  is connected to a third dust storage bin  80  via a fourth dust supply duct  71 , so that the ultra fine dusts collected in the second dust storage bin  70  are supplied to the third dust storage bin  80  via the fourth dust supply duct  71 . 
     A lower part of the third dust storage bin  80  is connected to an upper part of a gas distributor  32  of the final reducing furnace  30  via a fifth dust supply duct  81 . The fifth dust supply duct  81  is mounted with a dust charging feeder  82  at an upper part for controlling the amount of dusts which are supplied to the final reducing furnace  30 . The dust charging feeder  82  is mounted with a second nitrogen-injection device N 2  at a lower part for introducing the ultra fine dusts to the final reducing furnace  30  with high pressure. Accordingly, the ultra fine dusts which are injected into the upper part of the gas distributor  32  of the final reducing furnace  30  with the high pressure by the second nitrogen-injection device N 2  are coated on surfaces of the fine iron ores in the final reducing furnace  30 . 
     The dust separation device of the present invention as described above, is mounted with control valves  53 ,  63 ,  73 , and  83  on the respective dust supply ducts for stopping the flow of the dusts and gas in case of operating or repairing the device if it is necessary. 
     Now the method for manufacturing the molten pig iron by melting the fine iron ores of a wide particle size distribution by using the smelting reduction apparatus of the present invention will be described in more detail. 
     First, the fine iron ores fallen down from a charging bin  5  are supplied to a side of the pre-heating furnace  10  via an ore charging duct  1 , the iron ores of fine particles which are collected in the first cyclone  15  are supplied to a side of the pre-heating furnace  10  via a first circulation duct  17 , and the high temperature reducing gas which is discharged from the pre-reducing furnace  20  is supplied to a lower part of the pre-heating furnace  10  via the gas supply duct  28 . The fine iron ores and the iron ores of fine particles, which are supplied to the pre-heating furnace  10 , are preheated by the reducing gas in the pre-heating furnace  10 , forming a bubbling fluidized bed. 
     The pre-reducing furnace  20  is supplied with the fine iron ores preheated by the pre-heating furnace  10  via an ore charging duct  11  to a side, as well as the iron ores of fine particles, which are collected in the second cyclone  25 , via a second circulation duct  27  to a side. Further the pre-reducing furnace  20  is supplied with the high temperature reducing gas discharged from the final reducing furnace  30  to its lower part via a gas supply duct  38 . The fine iron ores and the iron ores of fine particles, which are supplied to the pre-reducing furnace  20 , are pre-reduced by the reducing gas in the pre-reducing furnace  20 , forming a bubbling fluidized bed. 
     The final reducing furnace  30  is supplied with the fine iron ores pre-reduced by the pre-reducing furnace  20  via an ore charging duct  21  to a side, as well as the iron ores of fine particles, which are collected in the third cyclone  35 , via a third circulation duct  37  to a side. Further the final reducing furnace  30  is supplied with the high temperature reducing gas discharged from the fourth cyclone  50  to its lower part via a gas supply duct  58 . The fine iron ores and the iron ores of fine particles which are supplied to the final reducing furnace  30  are finally preliminary reduced by the reducing gas in the final reducing furnace  30 , forming a bubbling fluidized bed. 
     As above, fine particle sponge iron, which is sequentially preliminary reduced while passing through the three-stage type fluidized bed reactor, are charged into the upper part of the melter-gasifier  40  via the ore discharge duct  31 . The melter-gasifier  40  is supplied with coal and high pressure oxygen in addition to the sponge iron which is supplied from the final reducing reactor  40  so as to finally reduce the sponge iron and melt, thereby producing the molten pig iron. 
     The melter-gasifier  40  generates a lot of exhaust gas of high temperature in the process of melting the sponge iron. 
     The exhaust gas contains ultra fine dusts which contains a lot of carbon and carbonized gas generated in the process of the burning of the charged coal. The dusts contained carbon and carbonized gas are sequentially separated by the dust separation device of the present invention. Now, the process for separating the exhaust gas will be described in more detail. 
     The exhaust gas, which is discharged from the melter-gasifier  40 , is supplied to the fourth cyclone  45  via the discharge duct  43 . The exhaust gas supplied to the cyclone is separated into dusts in the particle state and carbonized gas in the gas state by a strong centrifugal force, wherein the separated dusts are fallen down to a lower part in the cyclone and the carbonized gas is gathered to an upper part in the cyclone. The separated dusts collected to the lower part are re-supplied to the melter-gasifier  40  via the first dust supply duct  46 , while the separated carbonized gas is discharged to the fifth cyclone  50 , containing the ultra fine dusts which are not separated. 
     The fifth cyclone  50  secondarily collects the ultra fine dusts included in the supplied carbonized gas The carbonized gas from which the ultra fine dusts are separated is supplied to the final reducing furnace  30  to be used as the reducing gas. The ultra fine dusts collected in fifth cyclone  50  are supplied to the melter-gasifier  40  or the first dust storage bin  60 . 
     The dusts discharged to the first dust storage bin  60  are conveyed to the second dust storage bin  70  by the first nitrogen injection device N 1  and continuously supplied to the third dust storage bin  80 . 
     The dusts stored in the third dust storage bin  80  are injected to the upper part of the gas distributor  32  of the final reducing furnace  30  by the second is nitrogen injection device N 2  and coat the fine iron ore particles which are in bubbling fluidization state in the final reducing furnace  30 . 
     At this time, the pressure of the nitrogen supplied by the first and second nitrogen injection devices N 1  and N 2  is higher than the pressure in the furnace by 2˜3 times. The dusts are smoothly conveyed and stabled injected in the final reducing furnace  30  by the high pressure of the nitrogen. 
     An amount of the dusts which are introduced into the final reducing furnace  30  is preferably controlled to be 0.5˜1.0 wt % with relation to an amount of raw iron ores which are charged into the pre-heating furnace  10 . If the amount of the dusts which are introduced into the final reducing furnace  30  is less than 0.5 wt %, sticking prevention effect between the fine iron ores becomes reduced, while if the amount exceeds 1.0 wt %, the gas distributor may be clogged by the ultra fine dusts in next process. 
     It is preferable to control a velocity of the reducing gas in the pre-heating furnace  10 , the pre-reducing furnace  20  and the final reducing furnace  30  in the range of 1.2˜1.5 time of a minimum fluidizing velocity of the fine iron ores which are staying in the furnaces. By maintaining the velocity of the reducing gas as above, the respective fluidized bed reactors may form a stable bubbling fluidized bed. 
     Now, preferred embodiments are suggested to help the apparent understanding of the present invention. The below embodiments are provided for the sake of clear understanding only and the present invention is not limited thereto. 
     Embodiment 
     The specification and experimental conditions for the smelting reduction apparatus of the preferred embodiment of the present invention is as follows. 
     1) Specification of the fluidized bed reactor (the pre-heating furnace, the pre-reducing furnace, and the final reducing furnace) 
     Radius of the lower cylindrical part: 0.3 m 
     Radius of the upper cylindrical part: 0.6 m 
     Height of the lower cylindrical part from the upper part of the gas distributor: 3 m 
     Height of the upper cylindrical part from lower part of the inclination part: 3 m 
     2) Fine iron ores 
     Particle size of the fine iron ores: under 10 mm 
     Particle size distribution of the fine iron ores: 
     under 0.125 mm: 15.5%, 0.1250 0.25 mm: 10.0%, 
     0.25 0.5 mm: 9.1%, 0.51 0.0 mm 9.2%, 
     1.0 3.0 mm: 22.2% 3.05.8 0.0 mm: 19.5% 
     5.0 8.0 mm:13.7% 8.01 0.0 mm: 0.8% 
     Chemical composition of the fine iron ores 
     T. Fe: 63.49 wt %, FeO: 0.37 wt %, SiO 2 : 4.32 wt %, 
     Al 2 O 3 : 2.33 wt %, Mn: 0.05 wt %, S :0.007 wt %, 
     P: 0.063%, crystal water: 5.41 wt % 
     3) Reducing gas 
     Composition: CO: 65%, H 2 : 25%, CO 2 : 5%, N 2 : 5% 
     Temperature: 750-850 
     Pressure: 2.0-3.0 barg 
     4) Chemical composition of the dusts 
     T. Fe: 25-33 wt %, FeO: 10-15 wt %, SiO 2 : 8-10 wt %, 
     M. Fe: 10-15 wt %, Al 2 O 3 : 2-5 wt %, CaO: 2-5 wt %, 
     MgO: 1-2%, C: 45-55 wt %, S: 1-5 wt %, 
     Several experiments were carried out with the smelting reduction apparatus to examine the reduction of the fine iron ores. 
     The experimental results exhibited that reduced fine iron ores was begun to be discharged via the ore discharging duct  31  from the final reducing furnace  30  after 90 minutes from the beginning of the charging of the fine iron ores from the charging bin  5  into the pre-heating furnace  10 . 
     An average reduction degree of the fine iron ores which are discharged from the final reducing furnace  30  was exhibited 86˜90%, very excellent. An average gas utilization degree was 30-35%, and the gas consumption rate was 1350-1500 Nm 3 /t-ore. Further, a difference of pressure between the upper part and the lower part of the gas distributor of the final reducing furnace  30  was maintained in the range of 20-30 mbar, which was not increased even after a long time. As above, the small difference of pressure between the upper and lower parts of the gas distributor means that the clogging phenomenon of the gas distributor nozzle did not occur. Finally, the particle size distribution of the reduced iron which is preliminary reduced and discharged finally was exhibited uniform, which means that the sticking phenomenon between the fine iron ores did not occur in the respective fluidized bed reactors. 
     As shown from the result of the above embodiment, the smelting reduction apparatus according to the present invention may effectively prevent the clogging phenomenon of the gas distributor nozzle due to the dusts which is apt to occur in the related art fludized bed reactors. 
     Further, the sticking phenomenon between the reduced iron particles which may occur in the process of the reduction of the fine iron ores may be prevented by supplying the dusts containing a lot of carbon into the fluidizing bed reactors to coat the surfaces of the reduced iron. 
     While the present invention has been described in detail with reference to the preferred embodiment, those skilled in the art will appreciate that various modifications and substitutions can be made thereto without departing from the spirit and scope of the present invention as set forth in the appended claims.