KR100376498B1 - Smelting reduction apparatus and method for decreasing a scatter of fines - Google Patents

Abstract

The present invention relates to a melt reduction process for producing molten iron from iron ore using a fluidized-bed reactor and a melter gasifier, such as a FINEX process. The present invention relates to a molten reduction apparatus capable of effectively charging the reduced reducing iron produced / extracted from a reduction furnace into a molten gasifier and a molten reduction method using the apparatus. The present invention for achieving the above object, at least one fluidized bed reduction reactor (20, 30, 40), configured to reduce the charged iron ore while forming a fluidized bed,

A molten gasifier (10) configured to receive molten reducing iron from the fluidized bed final reduction furnace (20) of the fluidized bed reduction furnace to melt-reduce and manufacture molten iron;

The exhaust gas of the molten gas furnace 10 is collected, and the fine ore in the exhaust gas is circulated through the first dust recirculation pipe 52 to the molten gas furnace 10, and the exhaust gas from which the fine ore is removed is the fifth gas pipe 51. It includes a first cyclone (50) for supplying the reducing gas of the fluidized-bed reduction furnace (20, 30, 40) through,

The fluidized bed final reduction path 20 is connected to the molten gasifier 10 in the ore communication relationship through the ore charge tube 12, the other end of the first dust recycle pipe connected to the first cyclone 50 is melted In the melting reduction furnace is composed of a dust blowing device 60 is connected to the gasifier 10 by melting and agglomerated particulate ore,

The fine / small reduced iron in the reduced reducing iron supplied in connection with the first ore charge pipe 12 of the fluidized bed final reduction path 20 in the ore communication relationship is scattered upward by the gas supplied from the lower, and the medium / allele reduced iron Is a fluidized bed charging furnace 80 configured to reduce and form a fluidized bed and charge the molten gasifier,

The second cyclone 90 further collects fine / small particle reduced iron which is connected to the upper portion of the fluidized bed charging path 80 and is discharged to the upper portion, and the fine / small particle reduced iron is supplied to the molten combustion device. ,

The fluidized bed charging path 80 is equipped with an inclined gas distribution plate 82 at a lower portion thereof, and a gas supply pipe for supplying a reducing gas is connected to a bottom of the inclined gas distribution plate 82. The side wall of the flow-type charging passage adjacent to the upper side of the inclined gas distribution plate 82 is connected to the ring-shaped iron charging inlet 85 and of the flow-side charging passage 80 adjacent to the lower side of the inclined gas distribution plate 82. The sidewalls are connected with a reduced-iron iron outlet 83 for supplying medium / allele reduced iron, and the reduced-iron iron outlet 83 is connected with a molten gasifier charging pipe 86 for supplying the reduced-iron iron to a molten gasifier. The upper portion of the second cyclone 90 is connected to the gas outlet 91 for discharging the gas, the lower portion of the fine powder comprising a second dust recirculation tube 92 for discharging fine / small reduction iron is connected Pipe to molten reduction device with low scattering And that as a technical base.

Description

Smelting reduction apparatus and method for decreasing a scatter of fines}

The present invention relates to a melt reduction apparatus for producing molten iron from iron ore having a wide particle size using a fluidized-bed reactor and a melter gasifier, such as a FINEX process. More specifically, the present invention relates to a device for effectively charging the reduced iron produced and discharged in the fluidized bed final reduction furnace in the melt gasifier, and a melt reduction method using the same.

The main method for producing molten iron by reducing iron ore is to use blast furnace. In the raw material of the steelmaking process, iron ore of less than 8mm occupies about 70% or more, therefore, in the blast furnace process, molten iron ore is agglomerated through a sintering process and reduced in the blast furnace to manufacture molten iron. As such, since the blast furnace process undergoes a sintering process, an increase in facility investment cost for pretreatment and pollution problems arising from the pretreatment process are seriously occurring, and thus environmental regulations are being strengthened.

Therefore, the molten reduction method, which can produce molten iron by directly using ferrous ore, which has abundant reserves and low price, without undergoing a preliminary treatment process, is attracting attention as a new steelmaking method, and active research is being conducted mainly in advanced steel producing countries. The molten reduction steelmaking method is generally classified into a preliminary reduction step and a final reduction step. In the preliminary reduction step, the raw ore is reduced to solid state in the reduction furnace, and the final reduction step is carried out by charging the reduced reduced iron into the melting furnace and finally reducing the molten iron. Figure 1 shows the reduced iron ore of less than 8mm in the high-temperature reducing gas stream in the reactor of the multi-stage fluidized bed (20, 30, 40) to produce a fine reduced iron (Fine DRI) with a reduction rate of 80% or more to the melt gasifier (10) An example of the melt reduction apparatus applied to the direct steelmaking method which directly charges and manufactures molten iron | metal is shown.

In the fluidized bed steelmaking process, it is economical to charge the reduced-reduced iron produced / extracted from the fluidized bed final reduction furnace 20 directly into the melt gasifier 10 without omitting an expensive intermediate process such as hot briquetting. It is accepted as advantageous. However, when the charged reducing iron is charged into the molten gasifier 10 through the first ore charging tube of FIG. 1, the US / small particles of the charged reducing iron are scattered directly to the first cyclone 50, thereby reducing the cyclone efficiency. In this case, the dust content is increased in the reducing gas supplied to the fluidized bed final reduction path 20 through the fifth gas pipe 51, resulting in clogging of the nozzle of the gas dispersion plate 23, thereby preventing long-term operation. It is pointed out.

In the present invention, it was devised in the course of research to solve the above problems, the fine iron / small particles of reduced iron produced / discharged in the fluidized bed final reduction furnace separated from the reduced iron of the medium / allele, separated fine / small particles Reduced iron is charged into the molten gasifier through a dust burner to reduce the scattering of fine / small iron reduced iron in the molten gasifier, thereby reducing the burden on the first cyclone and clogging the nozzle of the gas dispersion plate. It is an object of the present invention to provide a melt reduction apparatus and a method capable of solving the phenomenon.

1 is an example of a melt reduction ore of reduced iron ore using a three-stage fluidized bed furnace and a melt gasifier

Figure 2 is a schematic diagram of a molten reduction apparatus further provided with a reduced iron charging device of the present invention

Explanation of symbols on the main parts of the drawings

10 ...... Melting furnace 11 ...... 1st gas pipe

12 ...... First Ore Charge 20 ...... Fluidized Bed Final Reduction Furnace

21 ...... 2nd gas pipe 22 ...... 2nd ore charging pipe

23 ...... First gas dispersion plate 30 ...... Second fluid bed reduction furnace

31 ...... 3rd gas pipe 32 ...... 3rd ore charge pipe

33 ...... 2nd gas dispersion plate 40 ...... 3rd fluidized bed reduction furnace

41 ...... 4th gas pipe 42 ......

50 ... 1st cyclone 51 ... 5th gas pipe

52 ...... 1st dust recirculation pipe 60 ...... dust blowing device

70 ...... Flue gas purifier 80 ...... Fluid bed charging furnace

81 ...... Gas supply port 82 ...... Inclined gas dispersion plate

83 ...... reduced iron outlet 84 ......

85 ............................................................................................................................

90 ... second cyclone 91 ... gas outlet

92 ...... 2nd dust recirculation tube 93 ...... Rotary cutting device

Melt reduction apparatus of the present invention for achieving the above object, at least one fluidized bed reduction reactor configured to reduce the charged iron ore while forming a minimum or bubble fluidized bed,

A molten gasifier (10) configured to receive molten reducing iron from the fluidized bed final reduction furnace (20) of the fluidized bed reduction furnace to melt-reduce and manufacture molten iron;

The exhaust gas of the melt gasifier is collected and the fine ore in the exhaust gas is circulated through the first dust recirculation pipe to the melt gasifier, and the exhaust gas from which the fine ore is removed is supplied as a reducing gas to the fluidized-bed reduction furnace through the fifth gas pipe. Contains 1 cyclone,

The fluidized bed final reduction path is connected to the molten gasifier in the ore communication relationship through the ore charge tube, and the other end of the first dust recycle tube connected at one end to the first cyclone is dust collected by dissolving particulate ore in the molten gasifier. In the melt reduction furnace composed of the blower is connected,

The fine / small reduced iron in the reduced reducing iron supplied in connection with the first ore charge pipe of the fluidized bed final reduction reactor is scattered upward by the gas supplied from the lower side, and the middle / allele reduced iron is reduced while forming the fluidized bed. Fluidized-bed charging furnace configured to charge the molten gasifier,

It further comprises a second cyclone to collect the fine / small reduced iron is scattered in connection with the upper portion of the fluidized bed charging furnace to discharge the gas to the top and supply the fine / small reduced iron to the molten combustion device,

The inclined gas distribution plate 82 is mounted at a lower portion of the fluidized bed charging path, and a gas supply pipe for supplying a reducing gas is connected to a bottom portion of the inclined gas distribution plate 82. To the side wall of the flow-type charging path adjacent to the upper side of the gas distribution plate 82 is connected to the distribution iron loading hole and to supply the medium / allele reduced iron to the side wall of the flow-side charging path adjacent to the lower side of the inclined gas distribution plate 82. The reduced-reduced iron outlet for connecting is connected to the molten gas-charging furnace charging pipe for supplying the reduced-reduced iron to the molten gasifier,

The upper portion of the second cyclone is connected to the gas outlet 91 for discharging the gas, the lower portion is configured to include a second dust recirculation pipe for discharging fine / small reduction iron is connected.

In addition, the method for producing molten iron using the melt reduction apparatus of the present invention described above,

In the bottom of the fluidized-bed charging furnace, one type of inert gas, natural gas, or Korex cooling gas is blown at one to three times the minimum fluidization rate of the average particle size of the ring reducing iron, and the ring reducing iron is supplied from the final bed of the fluidized bed. The reduced reducing iron of less than 150㎛ is collected by the second cyclone, and the medium / allele reduced iron larger than 150㎛ is reduced to form a fluidized bed and charged into the melt gasifier,

The fine / small particle reduced iron collected in the second cyclone is supplied to the dust injecting device, and is dissolved and agglomerated to be blown into the melt gasifier.

Hereinafter, the present invention will be described in detail.

In the present invention, the present invention has been completed in view of the fact that stable long-term operation is possible if the fine / small particles of reduced iron are separated from the differentiation iron produced and discharged from the fluidized bed final reduction furnace and blown into the molten gasifier through a dust blowing device. . The present invention, which focuses on these points, will be described with reference to the accompanying drawings, which are divided into a melt reduction apparatus and a method.

[Melting reduction device]

In general, the melt reduction apparatus is a fluidized-bed reduction furnace (20, 30, 40) for preliminarily reducing the iron ore in the flow state as shown in FIG. 1 and a melt gasification furnace (10) for melting molten reduction of the pre-reduced reduced iron (10). Is done. At least one fluidized bed reduction furnace is installed, and most preferably, three fluidized bed reduction furnaces are installed, and the present invention will be described based on this.

The fluidized-bed reduction furnaces 20, 30, and 40 are configured to form a fluidized bed with a reducing gas supplied from the bottom to reduce the iron ore or reduced iron and supply it to the next process, and exhaust gas is discharged to the top. That is, when the ferrous iron ore is supplied from the charging hopper to the third fluidized bed reduction furnace 40, the first reduction is supplied to supply the second fluidized bed reduction furnace 30, and the second fluidized bed is reduced again to the second fluidized bed reduction furnace 30 to finalize the fluidized bed. The reduction furnace 20 is supplied.

In the fluidized bed final reduction path (20), the reduced reducing iron is formed by reducing the fluidized bed, and then discharged to the first ore charge pipe (12) connected to the molten gasifier and the ore communication relationship to supply the reduced iron to the molten gasifier (10). do.

The melt gasifier 10 melt-reduces the reduced-reduction iron supplied through the first ore charge tube to produce molten iron and discharge the exhaust gas to the upper portion. The exhaust gas of the molten gas furnace 10 is collected in the first cyclone through the first gas pipe 11, the fine / small ore in the exhaust gas is supplied to the dust blowing device 60 through the first dust recirculation pipe (52). The fine or small ore is dissolved and agglomerated and blown in the molten gasifier 10.

In the present invention, the molten reduction apparatus configured as described above, receiving the reduced reducing iron from the fluidized bed final reduction furnace 20, the fine / small reduced iron in the reduced iron is scattered to the upper by the gas supplied from the lower and the medium / allele reduced iron A fluidized bed charging furnace 80 configured to reduce and charge the molten gasifier 10 while forming a fluidized bed;

The second cyclone 90 additionally collects fine / small particle reduced iron which is scattered by being connected to the upper portion of the fluidized bed charging path 80 and discharges the gas to the upper portion, and supplies the small / small particle reduced iron to the fusion combustion apparatus. , There is a feature.

Fluidized-bed charging furnace (80)

In the present invention, the fluidized bed charging path 80 is equipped with an inclined gas distribution plate 82 at the bottom thereof, and a gas supply pipe for supplying a reducing gas is connected to the bottom under the inclined gas distribution plate 82. The side wall of the flow-type charging path adjacent to the upper side of the inclined gas distribution plate 82 is connected to the ring reducing iron charging hole 85 and the flow-side charging path 80 adjacent to the lower side of the inclined gas distribution plate 82. Sidewalls of the iron reducing outlet 83 for supplying medium / allele reduced iron is connected. The reducing iron outlet 83 is connected to the melting gasifier charging pipe 86 for supplying the reducing iron to the molten gas furnace, and the reducing iron charging hole 85 is the first ore site of the fluidized bed final reduction furnace 20. It is connected to the entrance tube 12 in the ore communication relationship and receives a reduced iron.

The inclination angle of the inclined gas distribution plate 82 provided in the fluidized bed charging path 80 is 30 ° or less. When the inclination angle of the inclined gas dispersion plate 82 is greater than 30 °, the gas jet is inclined, so that the fluidized bed shape is not good.

In addition, the branched iron outlet 83 of the fluidized-bed charging furnace 80 may be provided with a screw conveyor 84, so that the branched iron is cut out to be loaded into the melt gasifier 10 by gravity. . The screw-type cutting device 84 can smoothly discharge the medium / opposed branched iron by adjusting the discharge speed by adjusting the rotation speed.

Second cyclone (90)

The second cyclone 90 is connected to an upper portion of the fluidized bed charging path 80 to collect fine / small particle reduced iron scattered from the upper part of the fluidized bed charging path 80 so that a gas outlet 91 is formed thereon. And the lower part of the fine / fine reduced iron is discharged to the second dust recirculation pipe 92 is connected to the lower.

The gas outlet 91 of the second cyclone is connected to the fifth gas pipe 51 of the first cyclone or connected to a second gas pipe for discharging the exhaust gas of the fluidized bed final reduction path 20 to supply gas to the reducing gas. .

In addition, the second dust recycling pipe 92 of the second cyclone may be directly connected to the dust blowing device 60 to the melt gasifier 10, but the dust blowing device through the first dust recycling pipe of the first cyclone At 60, fine / small particle reduced iron can be supplied. The lower portion of the second dust recirculation pipe 92 is preferably equipped with a rotary feeder 93.

[Melt reduction method]

In the present invention, by controlling the operating conditions in the fluidized bed charging furnace in the process of manufacturing molten iron using the melt reduction device described above to collect less than about 100㎛ in the first cyclone to collect the fine / small particles in the melt gasifier While reducing the amount of scattering of reduced iron, it improves the dissolution aggregation efficiency in the dust blowing device to more than 80%.

According to the present invention, one type of gas of inert gas, natural gas, or Korex cooling gas is blown at a lower portion of the fluidized bed charging path 80 at 1 to 3 times the minimum fluidization rate of the average particle size of the ring reducing iron, thereby completing the fluidized bed. The reduced reducing iron of 150 µm or less of the reduced reducing iron supplied from the reduction furnace 20 is collected by the second cyclone, and the heavy / allele reduced iron larger than 150 µm is reduced while forming a fluidized bed and charged into the molten gasifier. In the present invention, the gas flow rate is 1-3 times the minimum fluidization rate of the average particle size of the reduced ring iron, which is required to maintain the minimum fluidized state or the bubble fluidized bed, and 3 times the minimum fluidized rate of the average particle size of the iron atomized iron. If it becomes larger than 2 times, scattering loss occurs and cyclone efficiency falls. When the gas flow rate of the fluidized bed charging furnace is set to 1-3 times the minimum fluidization rate of the average particle size of the ring reducing iron, the flow becomes 150 μm or more, and less than that is collected as a second cyclone as fine / small particle reducing iron.

In addition, in the present invention, the fine / small particle reduced iron collected in the second cyclone is supplied to the dust blowing apparatus and melted and agglomerated into the molten gasifier.

Hereinafter, the present invention will be described in more detail with reference to Examples.

EXAMPLE

A charging / discharging test was performed under the conditions shown in Tables 2 to 3 using a fluidized bed charging apparatus (see FIG. 2) having the same size as in Table 1 below.

Fluidized bed charging furnace Dispersion Bore 0.74m Distribution Plate Tilt Angle 5 ° Charging furnace height (on the surface of the distributor plate) 4 m Inner diameter of outlet 19 cm Inner diameter of the charging slot 12 cm Height (in distribution plate) of outlet 15 cm Height of the charging slot 60 cm Threaded cutting device 0-1800 rpm

Chemical Composition and Particle Size Distribution of Iron Reducing Iron Chemical composition T.Fe: 75.4, Fe: 58.0, FeO: 17.3, SiO ₂ : 6.0 Particle size distribution -0.05mm: 5.4%, 0.05-0.15mm: 7.6%, 0.15-0.5mm: 20.1% 0.5-4.75mm: 55.3%, 4.75-8mm: 11.6%

Gas composition CO: 65%, H ₂ : 25, CO ₂ : 5%, N ₂ : 5% Temperature About 850 ℃ pressure 2.0 kgf / cm ² Velocity at Dispersion Surface 1.6 m / s Reducing Iron Charging / Ejection Rate About 0-1000 kg / hr

In the above experiments, the maximum particle size of the reduced-reduced iron scattered by the second cyclone and collected was 150 µm, and the reduced-reduced iron of 150 µm or more remained in the fluidized-bed charging path to form a bubbled fluidized bed, and within 1 minute after charging, Discharge by the device was possible, and it was also found that the discharge speed was adjusted smoothly by adjusting the rotation speed of the screw-type cutting device.

According to the results obtained from the field operation of the molten gasification furnace equipped with the first cyclone and the dust burner and producing about 2000 tons of molten iron per day, the maximum particle size collected in the first cyclone was 100 μm. The dissolution aggregation efficiency by the melting apparatus is 80% or more, which fully proves the feasibility of the present invention.

As described above, according to the present invention, it is possible to reduce the amount of scattering of fine / small-size reduced iron in the melt gasifier, thereby reducing the burden on the first cyclone, thereby eliminating the nozzle clogging of the gas dispersion plate and enabling stable long-term operation. There is a big advantage to doing this.

Claims (6)

One or more fluidized-bed reduction reactors 20, 30, 40 configured to reduce charged iron ore while forming a fluidized bed, A molten gasifier (10) configured to receive molten reducing iron from the fluidized bed final reduction furnace (20) of the fluidized bed reduction furnace to melt-reduce and manufacture molten iron; The exhaust gas of the molten gas furnace 10 is collected, and the fine ore in the exhaust gas is circulated through the first dust recirculation pipe 52 to the molten gas furnace 10, and the exhaust gas from which the fine ore is removed is the fifth gas pipe 51. It includes a first cyclone (50) for supplying the reducing gas of the fluidized-bed reduction furnace (20, 30, 40) through, The fluidized bed final reduction path 20 is connected to the molten gasifier 10 in the ore communication relationship through the ore charge tube 12, the other end of the first dust recycle pipe connected to the first cyclone 50 is melted In the melting reduction furnace is composed of a dust blowing device 60 is connected to the gasifier 10 by melting and agglomerated particulate ore, The fine / small reduced iron in the reduced reducing iron supplied in connection with the first ore charge pipe 12 of the fluidized bed final reduction path 20 in the ore communication relationship is scattered upward by the gas supplied from the lower, and the medium / allele reduced iron Is a fluidized bed charging furnace 80 configured to reduce and form a fluidized bed and charge the molten gasifier, The second cyclone 90 further collects fine / small particle reduced iron which is connected to the upper portion of the fluidized bed charging path 80 and is discharged to the upper portion, and the fine / small particle reduced iron is supplied to the molten combustion device. , The fluidized bed charging path 80 is equipped with an inclined gas distribution plate 82 at a lower portion thereof, and a gas supply pipe for supplying a reducing gas is connected to a bottom of the inclined gas distribution plate 82. The side wall of the flow-type charging passage adjacent to the upper side of the inclined gas distribution plate 82 is connected to the ring-shaped iron charging inlet 85 and of the flow-side charging passage 80 adjacent to the lower side of the inclined gas distribution plate 82. The sidewalls are connected with a reduced-iron iron outlet 83 for supplying medium / allele reduced iron, and the reduced-iron iron outlet 83 is connected with a molten gasifier charging pipe 86 for supplying the reduced-iron iron to a molten gasifier. The upper portion of the second cyclone (90) is connected to the gas outlet 91 for discharging the gas, the lower portion of the second dust recirculation pipe 92 for discharging fine / small reduction iron is connected to the made A melting reduction device with less scattering of fine powder. The molten reduction device of claim 1, wherein the inclined gas dispersion plate (82) is installed at an inclination of 30 degrees or less. The screw-type cutting device (84) according to claim 1, wherein the ring-reducing iron outlet (83) of the fluidized-bed charging furnace (80) cuts out the ring-reducing iron to be charged into gravity into the molten gas furnace (10). Melt reduction apparatus is less scattering of fine powder characterized in that it is provided. According to claim 1, wherein the gas outlet 91 of the second cyclone is connected to the fifth gas pipe 51 of the first cyclone or connected to the second gas pipe for discharging the exhaust gas of the fluidized bed final return path (20). A melting reduction device with less scattering of fine powder. The fine dust of claim 1, wherein the second dust recycle tube of the second cyclone is connected to supply fine / small particle reduced iron to the dust blowing device 60 through the first dust recycle tube of the first cyclone. Melt reduction apparatus with low scattering. In the method for producing molten iron using the melt reduction apparatus of claim 1, One type of gas of inert gas, natural gas, or Korex cooling gas is injected into the fluidized bed charging path 80 at a lower level of 1 to 3 times the minimum fluidization rate of the average particle size of the ring reducing iron. The reduced-reducing iron of 150 μm or less of the reduced-reduction iron supplied from) is collected by the second cyclone, and the heavy / allele reduced iron larger than 150 μm is reduced while forming a fluidized bed and charged into a molten gasifier, The fine / small particle reduced iron collected in the second cyclone is supplied to a dust blowing apparatus, melt-aggregated and blown into a melt gasifier, characterized in that the molten reduction method with less scattering of fine powder.