KR20000038827A - Flow-type pre-reduction apparatus of powder iron ore and pre-reducing method with the same - Google Patents

Abstract

PURPOSE: A pre-reducing method of powder iron ore is provided to improve reduction and gas-using rate by pre-reducing powder iron ore depending on particle size and to minimize the amount of dispersed powder iron ore. CONSTITUTION: Corpuscular iron ore is dispersed together with exhaust gas, and middle/large iron ore is introduced into a first gas feed pipe(126) from a first flow layer path(110). After that, the middle/large iron ore is reduced primarily as forming a vapor flow layer with reduction gas passing a first gas dispersing plate(112). The middle/large iron ore is charged into the intermediate portion of a second flow layer path(120) and reduced secondarily. The corpuscular iron ore is dispersed together with exhaust gas from the second flow layer path. The corpuscular iron ore is separates from gas in first and second cyclones(114,124) and charged into a third flow layer path(130). The corpuscular iron ore is secondarily reduced, separated from gas and circulates in the third path. The reduction iron of the second/third paths is finally discharged through second and third discharge pipes(121,131) respectively.

Description

Fluidized bed preliminary reduction device for iron ore and preliminary reduction method using the same

The present invention relates to a fluidized bed type preliminary reduction device for reducing a wider particle size distribution in a flow state and a preliminary reduction method using the same, and more particularly, to classify and reduce the iron ore having a wide particle size distribution according to particle size. The present invention relates to a fluidized bed preliminary reduction apparatus for iron ore and a preliminary reduction method using the same.

In the current molten iron production process, the blast furnace process is the mainstream. Recently, shaft-type molten reduction steel processing using pellets and lump ore has been commercialized to produce molten iron, but both processes have the limitation of using only the raw material. have.

In the blast furnace process, molten iron is produced using sintered ore processed by mixing coal coke, powdered iron ore and by-products. As a result, the increase in facility investment costs for pretreatment of raw materials and raw materials and pollution caused during pretreatment are seriously emerging, and environmental regulations are being strengthened accordingly. On the other hand, in the shaft-type molten iron reduction process is used to make the fine iron ore as a raw material pellets or to produce molten iron using a lump ore of limited particle size.

As such, in the blast furnace process or shaft-type molten reduction steelmaking process, powdered iron ore cannot be directly used and needs to be preliminarily processed. Therefore, it is possible to produce molten iron by directly using ferrous ore, which has abundant reserves and low cost, without undergoing pretreatment. The fluidized-bed molten reduced steelmaking process is drawing attention as the next-generation steelmaking process to replace the existing blast furnace process, and active research is being conducted mainly in the advanced steel producing countries.

The molten iron reduction process is generally divided into a preliminary reduction process and a final reduction process. In the preliminary reduction step, the raw ore is reduced to solid state in a reduction furnace, and in the final reduction step, the reduced reduction iron is charged into the melting furnace. To produce molten iron. The preliminary reduction process is generally classified into moving bed type and fluidized bed type according to the raw material ore's particle size.In the case of ferrite ore with small particle size and wide particle size distribution, the fluidized bed type which reduces raw material ore while flowing from reducing furnace to reducing gas is breathable. It is known to be efficient in terms of gas utilization.

An example of a charterer manufacturing apparatus may be those disclosed in Korean Patent No. 117065 (1997).

The molten iron manufacturing apparatus, as shown in Figure 1, to form a fluidized bed in the form of a fluidized bed in the form of a fluidized bed so as to stably flow the iron ore having a wide particle size distribution, the iron ore is a bubble fluidized bed to improve the reduction rate and gas utilization The first fluidized bed 10 to be dried / preheated in the state, the first cyclone 40 for collecting the fine iron ore contained in the exhaust gas of the first fluidized bed, and the preheated iron ore dried in the first fluidized bed The second fluidized bed furnace 20 for reducing, the second cyclone 50 for collecting the fine iron ore contained in the flue gas of the second fluidized bed furnace, and the final reduced powdered iron ore preliminarily reduced in the second fluidized bed furnace The molten iron is prepared by melting and reducing the reduced iron finally reduced in the furnace 30, the third cyclone 60 for collecting the fine iron ore contained in the exhaust gas of the third fluidized bed furnace, and the third fluidized bed furnace 30. And the the melter-gasifier 80 as the major component.

However, in the case of preliminary reduction of the iron ore using the conical three-stage fluidized bed preliminary reduction device as described above, the fine raw iron ore, which is not captured by the first cyclone 40, is scattered by the gas outlet and is scattered. The amount of ore can be high. In particular, considering that most of the differentiation phenomenon during the reduction of iron ore occurs in the early stage of reduction, a large amount of fine iron ore produced by reduction and differentiation during the first reduction and mechanical differentiation by flow is scattered in the first fluidized bed. By overloading, it inhibits the efficient separation of flue gas and iron ore, so that a large amount of fine iron ore can be released and lost together with the flue gas.

Thus, the present inventors conducted studies and experiments to solve the problems that may occur when pre-reduction of iron ore using the conventional fluidized bed pre-reduction device as described above, and proposed the present invention based on the results According to the present invention, a fluidized bed preliminary process of ferrite ore capable of minimizing the amount of fine iron ore that is scattered and lost at the same time as stabilizing fluidity by appropriately reducing the ferrite ore having a wide particle size distribution according to the particle size is improved. It is an object of the present invention to provide a reduction apparatus and a preliminary reduction method using the same.

1 is a schematic diagram schematically showing a fluidized bed reduction furnace of a conventional iron ore

2 is a block diagram of a fluidized bed pre-reduction device of the iron ore according to the present invention

Explanation of symbols on the main parts of the drawings

100 ... loading hopper 101 ... 1st loading

110.111 first fluidized bed road 1st ...

112 First gas dispersion plate 114 First cyclone

115 the first circulation pipe 120 the second fluidized bed

121 ... 2nd exhaust pipe 124 ... 2nd cyclone

125.2nd circulating pipe 130 ... 3rd fluidized bed furnace

131 ... 3rd discharge pipe 134 ... 3rd cyclone

135 The Third Circulation Tube

The present invention is a fluidized bed pre-reduction device of the iron ore to reduce the iron ore using a fluidized bed,

A first fluidized bed which receives a wider particle size distribution from the charging hopper and scatters the fine ore in the iron ore and the primary / allele is reduced by the bubble fluidized bed;

A second fluidized bed furnace for secondaryly reducing the primary reduced iron of medium / allele ore discharged from the first fluidized bed by the bubble fluidized bed;

A first cyclone for collecting particulate ore scattered from the first fluidized bed furnace;

A second cyclone to collect particulate ore scattered from the second fluidized bed furnace;

A third fluidized bed furnace receiving secondary particulates collected in the first cyclone and the second cyclone and performing secondary reduction by a bubble fluidized bed; And

The present invention relates to a fluidized bed preliminary reduction device for iron ore comprising a third cyclone for collecting and circulating ultrafine ore contained in the exhaust gas to the third fluidized bed.

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

An example of a fluidized bed preliminary reduction apparatus of ferrous ore according to the present invention is shown in FIG.

As shown in Figure 2, the fluidized bed preliminary reduction device of the iron ore according to the present invention is supplied from the charging hopper 100 is a wide particle size distribution of iron ore scattered fine ore in the iron ore and medium / allele ore A first fluidized bed furnace 110 which is primarily reduced by the bubble fluidized bed;

A second fluidized bed furnace (120) for secondaryly reducing the primary reduced iron of medium / allele ore discharged from the first fluidized bed (110) by the bubble fluidized bed;

A first cyclone (114) for collecting particulate ore scattered from the first fluidized bed (110);

A second cyclone 124 collecting particulate ore scattered from the second fluidized bed furnace 120;

A third fluidized bed furnace 130 which receives the particulate ore collected from the first cyclone 114 and the second cyclone 124 and reduces the secondary flow by the bubble fluidized bed 130; And

It comprises a third cyclone 134 to collect the ultra-fine ore contained in the exhaust gas of the third fluidized bed 130 and circulates to the third fluidized bed (130).

The first fluidized bed 110 has a cylindrical structure, and a first gas supply pipe 126 for supplying a reducing gas into a reduction furnace is connected to a bottom thereof, and a first gas distribution plate 112 is provided in a lower portion thereof. Is mounted.

In addition, the first side of the first fluidized bed 110 is connected to the charging hopper 100, the first charging pipe 101 for supplying the ferrous iron ore from the charging hopper 100 into the fluidized bed and the primary reduced / The first discharge pipe 111 for discharging the opposing ore to the second fluidized bed furnace 120 is connected.

In addition, an upper portion of the first fluidized bed passage 110 is connected to the first cyclone 114 through a first exhaust gas discharge pipe 113.

A first circulation pipe 115 is connected to a lower portion of the first cyclone 114 to circulate the particulate ore contained in the exhaust gas of the first fluidized bed 110 to the third fluidized bed 130. A fourth exhaust gas discharge pipe 116 for discharging the exhaust gas separated from the particulate ore is connected to the upper portion.

The second fluidized bed furnace 120 has a cylindrical structure, and a second gas supply pipe 141 for supplying a reducing gas into the reduction furnace is connected to a bottom thereof, and a second gas distribution plate 122 is provided in the lower part thereof. Is mounted.

In addition, the sidewall of the second fluidized bed 120 is connected to the first fluidized bed 110, the primary or secondary ore reduced from the first fluidized bed 110, the second fluidized bed 120 The first discharge pipe 111 for discharging to) and the second discharge pipe 121 for discharging secondary / reduced ore are connected.

In addition, an upper portion of the second fluidized bed passage 110 is connected to the second cyclone 124 through a second exhaust gas discharge pipe 123.

A second circulation pipe 125 for circulating particulate ore contained in exhaust gas of the second fluidized bed 120 to the third fluidized bed 130 is connected to a lower portion of the first cyclone 124. A first gas supply pipe 126 is connected to an upper portion of the exhaust gas separated from the particulate ore to the first fluidized bed 110.

In FIG. 2, the fine ore contained in the flue gas of the second fluidized bed 120 is sequentially supplied to the third fluidized bed 130 through the second circulation pipe 125 and the first circulation pipe 115. The circulation pipe 125 is in communication with the first circulation pipe 115.

The present invention is not limited thereto, and the second circulation pipe 125 may be directly connected to the third fluidized bed passage 130.

The third fluidized bed 130 has an image light narrowing structure formed of an enlarged upper portion 130a, an image light inclined portion 130b, and a reduced lower portion 130c.

A third gas distribution plate 132 is mounted in the reduced lower portion 130c, and a third gas supply pipe 142 for supplying a reducing gas is connected to a bottom portion below the third gas distribution plate 132. have.

In addition, a third discharge pipe 131 for discharging the finely-reduced iron reduced in the third fluidized bed 130 is connected to the side wall of the reduced lower portion 130c on the third gas distribution plate 132.

In addition, the enlarged upper portion 130a of the third fluidized bed 130 is connected to the third cyclone 134 through a third exhaust gas discharge pipe 133.

A third circulation tube 135 is connected to a lower portion of the third cyclone 134 to circulate particulate ore contained in the exhaust gas of the third fluidized bed 130 to the third fluidized bed 130.

In addition, a fifth exhaust gas discharge pipe 136 for discharging the exhaust gas separated from the particulate ore is connected to an upper portion of the third cyclone 134, and the fifth exhaust gas discharge pipe 136 is the fourth exhaust gas discharge pipe 116. It is desirable to communicate with).

Of course, in the present invention, the fifth exhaust gas discharge pipe 136 may not be in communication with the fourth exhaust gas discharge pipe 116.

In addition, one end of the first circulation pipe 115 passes through the enlarged upper portion 130a of the third fluidized bed 130 and is located inside the third fluidized bed 130.

The height of each of the first fluidized bed 110 and the second fluidized bed 110 is preferably 10-15 times its inner diameter, because if the height is less than 10 times the inner diameter of the iron ore in the furnace Because of the poor flow of iron or iron can also be scattered, and if the height is more than 15 times the inner diameter of the fine iron ore can not be efficiently scattered.

On the other hand, the inner diameter of the reduced lower portion 130c of the third fluidized bed 130 maintains the inner diameter of the lower end of the upper light inclined portion 130b, and the inner diameter of the enlarged upper portion 130a is the inner diameter of the upper end of the upper light inclined portion 130b. Keep it.

The inner diameter of the enlarged upper portion 130a is preferably selected in the range of 1.5-2.0 times the reduced lower inner diameter in order to reduce the gas flow rate in the furnace to suppress the scattering of the fine iron ore.

In addition, the total height of the third fluidized bed 130 is preferably selected to be in the range of 10-20 times the inner diameter of the reduced bottom in order to secure a sufficient flow space and to suppress the scattering of the fine iron ore, the reduced bottom 130c The height of is preferably selected in the range of 1.0-1.5 times the height of the enlarged upper portion 130a.

On the other hand, the inclination angle of the image light inclined portion 130b is preferably selected in the range of 30-50 degrees from the vertical line.

Hereinafter, a method for producing reduced iron using the fluidized bed preliminary reduction apparatus of the iron ore of the present invention will be described.

Particulate iron ore from the ore-loading hopper 100, which is charged into the first fluidized bed 110 through the first charging pipe 101, is dispersed with the exhaust gas, and the iron ore of the medium / composition is the first. It is first reduced while forming a bubble fluidized bed by the reducing gas flowing into the first gas supply pipe 126 from the fluidized bed 110 and passing through the first gas distribution plate 112.

The iron ore of the primary / allele reduced in the first fluidized bed 110 is discharged through the first discharge pipe 111 to be charged into the fluidized bed stop of the second fluidized bed 120 and to the second gas supply pipe 141. Secondary reduction is performed by forming a bubble fluidized bed by the supplied reducing gas.

Also, in the second fluidized bed furnace 120, as in the first fluidized bed furnace 110, the fine iron ore is scattered together with the exhaust gas.

On the other hand, the fine iron ore scattered from the first fluidized bed 110 and the second fluidized bed 110 is separated from the gas in the first cyclone 114 and the second cyclone 124, respectively, the first circulation pipe The secondary fluid is charged into the third fluidized bed passage 130 through the 115 and the second circulation pipe 125 and is secondaryly reduced while forming a bubble fluidized bed by the reducing gas introduced into the third gas supply pipe 142.

The ultrafine iron ore scattered together with the exhaust gas in the third fluidized bed furnace is separated from the gas in the third cyclone 134 and circulated to the third fluidized bed path 130 through the third circulation pipe 135.

The reduced iron secondary reduced in the second fluidized bed 120 and the third fluidized bed 130 is finally discharged through the second discharge pipe 121 and the third discharge pipe 131, respectively.

Gas flow rates in the first fluidized bed furnace 110 and the second fluidized bed furnace 120 are 1.2-2.5 times the minimum fluidization rate of iron ore staying in the furnace for efficient separation and smooth flow of fine and medium / allele ores. It is preferable to select in the range of.

The flow rate of the gas in the furnace of the third fluidized bed 130 is preferably selected to be in the range of 1.2-2.0 times the minimum fluidization rate of the iron ore staying in the furnace, which is an appropriate flow rate range of the bubble fluidized bed.

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

Example

Reduced iron was prepared under the conditions shown in Tables 4 and 5 by using a powdered ore having a chemical composition and particle size distribution of Tables 2 and 3 as a preliminary reduction device of FIG.

Internal diameter and height of fluidized bed preliminary reactor Fluidized bed size First fluidized bed Inner diameter: 0.5m Height: 5.0m (from the top of the dispersion plate) Second fluidized bed Inner diameter: 0.5m Height: 5.0m (from the top of the dispersion plate) Third fluidized bed Reduced inner diameter: 0.3 m Expanded target inner diameter: 0.6 m Reduced bottom height: 3 m (from the top of the distribution plate)

Chemical Composition of Raw Ore ingredient T.Fe FeO SiO ₂ Al ₂ O ₃ Mn S P moisture wt.% 63.49 0.37 4.32 2.33 0.05 0.007 0.063 5.41

Particle Size Distribution of Raw Ore Particle size (mm) <0.125 0.25-0.125 0.5 ~ 0.25 1 ~ 0.5 3 ~ 1 5 ~ 3 5 to 8 8 to 10 wt.% 14.5 10.0 9.1 9.2 22.2 17.5 10.4 7.1

Reducing gas condition Gas composition CO: 65%, CO ₂ : 5%, H ₂ : 25%, N ₂ : 5% Temperature 750 ~ 850 ℃ pressure 1.5 ~ 2.0 kgf / cm ²

Gas flow rate in fluidized bed Fluidized bed Gas flow rate First fluidized bed Flow rate: 2.5 m / s Second fluidized bed Flow rate: 2.5 m / s Third fluidized bed Lower flow rate: 0.4 m / s Target flow rate: 0.1 m / s

As a result of the production of reduced iron under the above conditions, the ore loading started from the charging hopper into the first fluidized bed furnace, and about 60 minutes later, the reduced iron was discharged through the reduced iron discharge pipe. 88 to 92% of the discharged medium / allele, 86 to 90% of the fine particles discharged from the third fluidized bed 130, it was possible to obtain a uniform reduction rate regardless of the particle size. In addition, the average gas utilization rate was 30-35%, and the gas source unit was 1350-1500 Nm ³ / t-ore. On the other hand, the scattering ratio was very good within 5%.

As described above, the present invention can reduce the scattering loss that may occur in the reduction by reducing the load of the cyclone that can appear in the conventional fluidized bed pre-reduction device and can efficiently reduce the iron ore having a wide particle size distribution according to the particle size It works.

Claims (5)

In the fluidized bed pre-reduction device of the iron ore for pre-reduction of iron ore having a wide particle size distribution, A first fluidized bed furnace 110 which receives a wider particle size distribution from the charging hopper 100 and scatters fine ore in the iron ore and primarily reduces the medium / allele by the bubble fluidized bed; A second fluidized bed furnace (120) for secondaryly reducing the primary reduced iron of medium / allele ore discharged from the first fluidized bed (110) by the bubble fluidized bed; A first cyclone (114) for collecting particulate ore scattered from the first fluidized bed (110); A second cyclone 124 for collecting particulate ore scattered from the second fluidized bed furnace 120; A third fluidized bed furnace 130 which receives the particulate ore collected from the first cyclone 114 and the second cyclone 124 and reduces the secondary flow by the bubble fluidized bed 130; And And a third cyclone 134 for collecting the ultrafine ore contained in the exhaust gas of the third fluidized bed 130 and circulating to the third fluidized bed 130. The first fluidized bed 110 has a cylindrical structure, and a first gas distribution plate 112 is mounted in a lower portion of the first fluidized bed furnace 110, and a lower portion of the first fluidized bed furnace 110 is provided to supply exhaust gas of the second fluidized bed furnace 120 used as a reducing gas. The first gas supply pipe 126 for connecting is connected to the side wall of the first charging pipe 101 for supplying the iron ore stored in the raw material loading hopper 100 into the first fluidized bed 110 and the primary / A first discharge pipe 111 for discharging allele ore is connected; An upper portion of the first fluidized bed 110 is connected to the first cyclone 114 through a first exhaust gas discharge pipe 113, and a lower portion of the first fluidized bed 110 is located below the first cyclone 114. A first circulation pipe 115 for circulating the particulate ore contained in the exhaust gas to the third fluidized bed passage 130 is connected, and a fourth exhaust gas discharge pipe 116 for discharging the exhaust gas separated from the particulate ore is connected thereon. Is connected; The second fluidized bed 120 has a cylindrical structure, and a second gas distribution plate 122 is mounted in a lower portion thereof, and a second gas supply pipe 141 for supplying a reducing gas is connected to a bottom thereof. The first discharge pipe 111 is connected to the first fluidized bed 110 on the side wall to discharge the heavy / allele ore, which is primarily reduced from the first fluidized bed 110, to the second fluidized bed furnace 120. And a second discharge pipe 121 for discharging secondary reduced heavy / allele ore; An upper portion of the second fluidized bed 110 is connected to the second cyclone 124 through a second exhaust gas discharge pipe 123, and a lower portion of the second fluidized bed 120 is located below the first cyclone 124. A second circulation pipe 125 for circulating the particulate ore contained in the flue gas to the third fluidized bed furnace 130 is connected, and the exhaust gas separated from the particulate ore is supplied to the first fluidized bed furnace 110 at an upper portion thereof. A first gas supply pipe 126 for connecting is connected; The third fluidized bed 130 has an upper light narrowing structure composed of an enlarged upper portion 130a, an upper light inclined portion 130b, and a reduced lower portion 130c, and a third gas distribution plate (3) in the reduced lower portion 130c. 132 is mounted, and a third gas supply pipe 142 for supplying a reducing gas is connected to a bottom portion below the third gas distribution plate 132, and the upper portion of the third gas distribution plate 132. A third discharge pipe 131 for discharging the finely-reduced iron reduced in the third fluidized bed 130 is connected to the side wall of the reduced lower portion 130c; The enlarged upper portion 130a of the third fluidized bed 130 is connected to the third cyclone 134 through a third exhaust gas discharge pipe 133, and the third fluidized bed is disposed below the third cyclone 134. A third circulation pipe 135 for circulating the particulate ore contained in the exhaust gas of the furnace 130 to the third fluidized bed furnace 130 is connected, and is separated from the particulate ore at the upper portion of the third cyclone 134. Fluidized bed pre-reduction device of the iron ore, characterized in that the fifth exhaust gas discharge pipe 136 for discharging the exhaust gas is configured to be connected The method of claim 1, wherein the second circulation pipe 125 is in communication with the first circulation pipe 115, and the fifth exhaust gas discharge pipe 136 is connected to the fourth exhaust gas discharge pipe 116. Fluidized bed pre-reduction device of iron ore characterized in that According to claim 1 or 2, wherein the height of each of the first fluidized bed 110 and the second fluidized bed (120) is 10-15 times its inner diameter, the reduced bottom of the third fluidized bed (130) ( The inner diameter of 130c) maintains the inner diameter of the lower end of the upper light inclined portion 130b, and the inner diameter of the enlarged upper portion 130a maintains the inner diameter of the upper end of the upper light inclined portion 130b, and the inner diameter of the enlarged upper portion 130a. Is 1.5-2.0 times the diameter of the reduced lower part, the total height of the third fluidized bed 130 is 10-20 times the diameter of the reduced lower part, and the height of the reduced lower part 130c is 1.0-1.5 times the height of the enlarged upper part 130a, And the inclination angle of the ordinary light inclined portion 130b is 30-50 ° with respect to the vertical line. The ferrous iron ore of claim 1 was charged with a wide particle size distribution from the ore charging hopper 100 to the first fluidized bed furnace 110 through the first charging pipe 101 using the fluidized bed preliminary reduction device of the iron ore of claim 1. The fine iron ore of the iron ore is scattered together with the exhaust gas, and the iron ore of the medium / elasticity is first reduced while forming a bubble fluidized bed by the reducing gas passing through the first gas distribution plate 112 in the first fluidized bed 110. , The primary ore iron ore reduced in the first fluidized bed 110 is charged into the fluidized bed stop portion of the second fluidized bed 120 through the first discharge pipe 111 and is supplied to the second gas supply pipe 141. Secondary reduction while forming a bubble flow layer by reducing gas, and then discharged through a second discharge pipe 121, Particulate iron ore scattered from the first fluidized bed 110 and the second fluidized bed 110 is separated from the gas in the first cyclone 114 and the second cyclone 124, respectively, and the first circulation pipe 115 is. ) And charged into the third fluidized bed passage 130 through the second circulation pipe 125 to form a bubble fluidized bed by reducing gas introduced into the third gas supply pipe 142, followed by secondary reduction, and then a third discharge pipe ( 131), In addition, the ultrafine iron ore scattered together with the exhaust gas in the third fluidized bed 130 is separated from the gas in the third cyclone 134 to be circulated to the third fluidized bed 130 through the third circulation pipe 135. In the method of preliminary reduction of iron ore. The gas flow rates in the first fluidized bed furnace 110 and the second fluidized bed furnace 120 are 1.2-2.5 times the minimum fluidization rate of the iron ore remaining in the furnace; And Flow rate pre-reduction method of the iron-iron ore, characterized in that the flow rate of the gas in the furnace of the third fluidized bed 130 is 1.2-2.0 times the minimum fluidization rate of the iron ore in the furnace. The height of each of the first fluidized bed furnace 110 and the second fluidized bed furnace 120 is 10-15 times its inner diameter, and the inner diameter of the reduced lower portion 130c of the third fluidized bed furnace 130 is defined. Silver maintains the inner diameter of the lower end of the upper light inclined portion 130b, the inner diameter of the enlarged upper portion 130a maintains the inner diameter of the upper end of the upper light inclined portion 130b, the inner diameter of the enlarged upper portion 130a is a reduced inner diameter Is 1.5-2.0 times, and the total height of the third fluidized bed 130 is 10-20 times the reduced inner diameter, and the height of the reduced lower portion 130c is 1.0-1.5 times the height of the enlarged upper portion 130a, and the upper diameter is Fluidized bed preliminary reduction method of iron ore, characterized in that the inclination angle of the sand portion 130b is 30-50 degrees with respect to the vertical line