JPH0726139B2 - Ore reduction furnace and reduction device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reducing furnace for reducing a metal oxide ore such as iron ore, and a reducing apparatus for using such a reducing furnace as a preliminary reducing furnace in combination with another reducing furnace. In the following, iron (and iron ore) is taken as an example of the metal (and metal oxide ore), and the description will be centered on it.

[0002]

2. Description of the Related Art An iron making method by smelting reduction is a method of obtaining pig iron by reducing iron ore in a molten state using a smelting reduction furnace. The smelting reduction furnace has advantages such as quick reaction and capable of elastically adjusting the production amount, but on the other hand, since the energy utilization rate is low, a smelting reduction system in which a preliminary reduction furnace is used in combination with this is often constructed. The gas generated in the smelting reduction furnace (high-temperature gas containing CO and having a reducing property) is introduced into the preliminary reduction furnace as a reducing gas, where the iron ore is preliminary in a solid state (up to preliminary reduced iron). After being reduced, it is charged into a smelting reduction furnace.

As the preliminary reduction furnace, a fluidized bed type reduction furnace in which iron ore is fluidized and reduced by the above-mentioned reducing gas is often adopted. This is because if the fluidized bed type is used, the iron ore powder and granules can be used as a raw material as it is, and it can be continuously and uniformly processed.

FIG. 3 shows a conventional configuration and connection state of a smelting reduction furnace and a fluidized bed type preliminary reduction furnace. Smelting reduction furnace 6
At 0, iron ore (preliminary reduced iron) is charged into the molten metal 61a through the charging pipe 63, and coal and oxygen (not shown) are also charged. The gas generated in the smelting reduction furnace 60 is guided from the gas introduction pipe (duct) 51 to the lower portion of the preliminary reduction furnace 50, and is sent into the fluidized bed chamber 53 in the upper portion of the furnace through the rectifying nozzle 52a provided in the dispersion plate 52. There, the iron ore is fluidized to form a fluidized bed 53a and preliminary reduction is performed.
Iron ore as a raw material is charged into the furnace 50 (fluidized bed chamber 53) from a charging pipe 59 at the upper part of the preliminary reduction furnace 50,
It is taken out of the same furnace 50 through a discharge pipe 56 that opens into the fluidized bed 53 a, collected in a tank 57, and then sent to a smelting reduction furnace 60 through a charging pipe 63. Japanese Patent Laid-Open No. 1-129916
These points are the same in the technology described in the publication. It should be noted that reference numerals 57a and 57b in FIG. 3 denote valves for cutting out powder particles having a pressure difference holding function between the upper and lower sides.

[0005]

The preliminary reduction furnace and the smelting reduction system as shown in FIG. 3 have room for improvement in the following points.

(A) Since the temperature of the reducing gas introduced into the preliminary reduction furnace 50 must be raised in the gas introduction pipe 51, the heat resistance of the gas passage portion such as the pipe 51 and the dispersion plate 52 is considerable. Need consideration. In order to efficiently reduce iron ore in a solid state, the temperature in the preliminary reduction furnace 50 is set to about 800
The reaction temperature must be kept at ℃, but since iron ore at about room temperature is charged into the furnace 50 as a raw material through the charging pipe 59, the temperature of the introduced gas upstream of the dispersion plate 52 (nozzle 52a) is about 1000 ° C. Temperature is required. At such a temperature, a very special material is required as a refractory material for the introduction pipe 51 and a material for the dispersion plate 52, and iron ore easily attaches / welds to the nozzle 52a, etc. Sometimes you can't raise the rate.

(B) It is necessary to dispose an input facility for raw iron ore at a high position, which increases the facility cost including the steel frame structure (building). That is, a tank (not shown) or the like is provided above the charging pipe 59 in order to charge the raw material iron ore into the upper part of the preliminary reduction furnace via the charging pipe 59.
Iron ore must be carried to that point by a conveyor (same). As shown in FIG. 3, the preliminary reduction furnace 50 is replaced by the smelting reduction furnace 6
When used in combination with 0, the position of the tank etc. becomes particularly high. Further, conveyors and the like are required to have a high capacity (large capacity) in order to handle the entire amount of iron ore.

(C) The gas generated from the smelting reduction furnace 60 contains dust such as iron powder. When such gas is used as the reducing gas for the preliminary reduction furnace 50, the dust is introduced into the gas introduction pipe 51.
It adheres to the inner surface of the and easily accumulates. This is because the refractory (usually rough surface) is stretched on the inner surface of the introduction pipe 51 as described above, but iron powder or the like tends to be deposited on the refractory because of the high temperature atmosphere. It is also because of it. Further, the same dust is likely to adhere to the rectifying nozzle 52a of the dispersion plate 52. If such a situation progresses, it will be necessary to clean it and the operating rate will decrease.

According to the present invention, the temperature of the reducing gas in the gas introduction pipe can be set lower than before, and the burden on the equipment for the input of the raw ore can be reduced, and a reduction furnace for such reduction is preliminarily reduced. The present invention is to provide a reducing device which is used as a furnace in combination with another reducing furnace, and in which dust is unlikely to adhere to or deposit on a gas introduction pipe or a rectifying nozzle.

[0010]

In the ore reduction furnace according to the present invention (claim 1), the reducing gas is sent from the gas introduction pipe in the lower part of the furnace body to the upper part of the furnace body through the rectifying nozzle. It is a reduction furnace that fluidizes and reduces metal oxide ore, but the inlet of raw material ore is provided in (upstream of) the gas introduction pipe, and the opening size and inner material of the pipe and the shape of the rectifying nozzle and The opening size is set so that the ore is transported from the charging position to the reducing gas on the nozzle. For example, the opening size of the gas inlet pipe is
Considering the type and particle size of the ore charged from the above-mentioned inlet and the amount of reducing gas passing through the pipe, set the gas flow velocity to a small size (thin) so that the gas flow velocity is a sufficient value for air transport of the ore. . As the inner material of the pipe, a material having wear resistance that is less likely to be worn by the ore transported by air flow and moderate heat resistance is selected. Further, the rectifying nozzle is provided with a shape and a size that allow the ore transported from below to pass smoothly and be fed into the upper fluidized bed.

The ore reducing apparatus according to the present invention (claim 2)
Uses the above-mentioned reduction furnace as a preliminary reduction furnace together with another reduction furnace (for example, a smelting reduction furnace), and ore as a raw material is used as a reducing gas to generate gas in another reduction furnace introduced into the preliminary reduction furnace. It is transported to a preliminary reduction furnace and then subjected to preliminary reduction, and the ore is charged into another reduction furnace and finally reduced.

[0012]

In the reducing furnace according to claim 1 of the present invention, the raw material ore charged from the charging port is carried by the reducing gas in the gas introducing pipe in which the size and material are set as described above. , Passes through the rectifying nozzle having the shape and size as described above, and is fed to the upper fluidized bed, where it is fluidized and reduced. With this, there are the following effects.

First, since the raw material ore at room temperature and the reducing gas at high temperature come into contact with each other in the middle of the gas introduction pipe, the ore is preheated to some extent by the time it reaches the inside of the fluidized bed, and the reducing gas is somewhat reduced. To be cooled. Therefore, even if the fluidized bed is kept at the same reaction temperature (for example, about 800 ° C. for iron ore), the gas temperature in the gas introduction pipe until then becomes lower than that of the conventional fluidized bed reduction furnace. And the heat load on the rectifying nozzle is reduced. Since the ore is preheated by the time it reaches the fluidized bed, it also has the effect of shortening the time for which the ore should remain in the fluidized bed.

Further, since the raw material ore can be charged from below the fluidized bed or the rectifying nozzle, the equipment for the charging can be arranged at a low position or the height of the equipment can be lowered. For example, a tank for temporarily storing ore may be located at a low position, and conveyors for transporting ore to that position may be of low height. Even if only a part of the ore is charged from the charging port of the gas introduction pipe, it is advantageous in terms of cost in terms of tank capacity, conveyor capacity, etc., compared to the case where the entire amount of ore is charged from the upper part of the furnace body.

According to the reducing apparatus of claim 2, as the reducing gas in the preliminary reducing furnace (the reducing furnace of claim 1), the gas generated in another reducing furnace, which generally contains dust, is used. Nevertheless, dust does not adhere to or accumulate inside the preliminary reduction furnace (for example, the gas introduction pipe or the rectifying nozzle). This is because the raw ore is transported to the preliminary reduction furnace by being carried on the above gas, and even if there is attached dust, the ore is immediately removed by the ore. Since the ore preliminarily reduced in the preliminary reduction furnace is charged into another reduction furnace through a route different from that of the above gas, it is not difficult to adjust the charging amount. It should be noted that the above-described effect that the heat load of the preliminary reduction furnace can be reduced and the facility for charging the raw material ore can be easily provided is also exhibited in this reduction method.

[0016]

FIG. 1 shows a first embodiment of the present invention.
It is sectional drawing which shows the outline | summary about the reduction | restoration apparatus containing two reduction furnaces, and the whole smelting reduction system by it. In the figure,
Reference numeral 10 indicates a fluidized bed type preliminary reduction furnace for iron ore, and reference numeral 20 indicates a smelting reduction furnace.

The pre-reduction furnace 10 has a gas introducing pipe 11 at the bottom.
And a fluidized bed chamber 13 above the gas rectifying nozzle 12.
Is equipped with. In the fluidized bed chamber 13, the iron ore forms the fluidized bed 13a by the reducing (combined fluidizing) gas sent through the nozzle 12, and is heated and reduced there to become preliminary reduced iron. An exhaust gas pipe 14 is provided in the upper part of the fluidized bed chamber 13, and a cyclone 15 for collecting scattered fine particles of pre-reduced iron is interposed in the upper part of the fluidized-bed chamber 13, and a valve 15a for cutting is provided under the cyclone 15. Are connected. A discharge pipe 16 is connected downward to the fluidized bed chamber 13, and a storage tank 17 for pre-reduced iron is connected to a valve 17 at the tip of the discharge pipe 16.
It is provided with a.17b.

In the smelting reduction furnace 20, molten iron pig iron (a molten iron) 21a in the furnace body 21 is charged with pre-reduced iron as well as coal which is a reducing agent and oxygen which is a combustion agent thereof. Is what you get. In the figure, reference numeral 23 is a charging pipe for preliminary reduced iron from the storage tank 17, and 24 is a blowing pipe for charging the fine preliminary reduced iron collected by the cyclone 15 together with the iron bath stirring gas. Further, reference numeral 25 is a coal and auxiliary raw material charging pipe, and reference numeral 26 is an oxygen blowing lance. During operation, a high-temperature reducing gas containing a large amount of CO (carbon monoxide) is generated from the iron bath 21a, so this is collected at the furnace top 22 and sent to the preliminary reduction furnace 10 as a reducing gas. There is.

A major feature of this system is that (unreduced) iron ore as a raw material is put on the above-mentioned reducing gas which is generated in the smelting reduction furnace 20 and is sent to the preliminary reduction furnace 10 so as to be reserve by so-called air flow transportation. Fluidized bed 13a in reduction furnace 10
It is to carry to. For this purpose, the preliminary reduction furnace 10 is configured as follows.

A) The raw iron ore charging port 19 is provided at an upstream portion of the gas introduction pipe 11 of the preliminary reduction furnace 10, that is, at a position near the smelting reduction furnace 20. In the inlet 19,
A storage tank 18 equipped with valves 18a, 18b for cutting out iron ore was connected via a charging pipe 18c.

B) Regarding the introduction pipe 11, the smelting reduction furnace 2
At 0, the diameter was made small so that the gas flow velocity that enables stable air flow transport of iron ore can be obtained even if the operating conditions fluctuate slightly, and it has excellent wear resistance so that the iron ore transported does not easily wear. Lined refractory. In this example, iron ore having a particle size of 3 mm or less is used as a raw material, and the inner diameter of the introduction pipe 11 is determined so that the gas flow rate is 20 to 30 m / sec. Introductory pipe 1 to nozzle 12
It goes without saying that there was no flow stagnant portion in 1 and the flow path change was moderated by increasing the radius of curvature of the curved portion to facilitate the transportation of iron ore. Introducing a communication pipe (the same) to the outside via a damper (not shown) or the like so that the amount and temperature of gas can be adjusted.
You can also connect to.

C) One-hole nozzle 12 following the introduction pipe 11.
In order to make it easier for iron ore to pass through, the cross-sectional area was gradually reduced from below and expanded again in the upper fluidized bed chamber 13. The inner diameter of the nozzle 12 is set so that the gas flow velocity here is 100 m / sec so as to contribute to the preferable formation of the fluidized bed 13a.
It is set to be before and after.

D) The fluidized bed chamber 13 on the nozzle 12 needs to have a predetermined cross-sectional area in the inner opening so that the iron ore sent from below forms the fluidized bed 13a and stays in the chamber. In this example, the gas flow velocity at the opening is about 3 m / sec.
The cross-sectional area is given as

According to the above a) to d), the iron ore as a raw material undergoes the following processes. That is, it is charged into the introduction pipe 11 from the tank 18 provided at a relatively low position through the charging port 19. The reducing gas coming from the smelting reduction furnace 20 is transported by air flow so that the introduction pipe 11 and the nozzle 1
The fluidized bed chamber 13 while removing the dust adhering to the inner surface of 2 and receiving the thermal and chemical energy of the reducing gas.
Will be sent to. In the same chamber 13, it forms a fluidized bed 13a and stays, and during that time, preliminary reduction is performed. After being discharged and stored from the discharge pipe 16 to the tank 17, it is charged into the smelting reduction furnace 20 through the charging pipe 23. The fine particles scattered on the fluidized bed 13a and flowing out from the exhaust gas pipe are collected by the cyclone 15 and charged into the smelting reduction furnace 20 as described above.
The iron ore (pre-reduced iron) of any of the above
It is melted and reduced in the zero iron bath 21a to become pig iron.

Next, FIG. 2 shows a reducing furnace as a second embodiment of the present invention. The illustrated reduction furnace 30 is also a fluidized bed furnace used for preliminary reduction of iron ore (illustration of the smelting reduction furnace is omitted), and also the charging port 3 provided in the reducing gas introduction pipe 31.
Although iron ore as a raw material is charged from 9A and sent to the fluidized bed chamber 33 from below by air transport of the same gas, it differs from the preliminary reduction furnace 10 in FIG. 1 in the following points.

A) The entire amount of raw iron ore is introduced into the gas introduction pipe 31.
If the iron ore is coarse-grained (for example, having a diameter of 5 mm or more) instead of being sent from
It is directly charged from B into the fluidized bed chamber 33. Therefore, there is an advantage that it is not necessary to finely crush the iron ore to adjust the particle size, and it is easy to handle when the amount of the reducing gas is small.

(B) A dispersion plate 32 is provided between the introduction pipe 31 and the fluidized bed chamber 33, and a plurality of rectifying nozzles 32a are formed therein. However, in order to prevent the iron ore from being caught on the lower surface of the dispersion plate 32, the portion between the nozzles 32a was formed in a downward sharpened shape. Needless to say, the diameter of each nozzle 32a is larger than the maximum diameter of the iron ore sent from the introduction pipe 31.

C) The upper surface of the dispersion plate 32 is formed into a funnel shape,
A discharge pipe 36 for preliminary reduced iron was connected to the central portion. Coarse-grained iron ore that is not fluidized in the fluidized-bed chamber 33 is temporarily deposited on the dispersion plate 32 to form the moving bed 33b, which comes into contact with the reducing gas, and the intermediate-grained iron ores reduced in the fluidized bed 33a It is discharged from the discharge pipe 36 together with the preliminary reduced iron. Since the cyclone 35 provided in the exhaust gas pipe 34 collects the fine reduced particles of the pre-reduced iron, the reduction furnace 30 can simultaneously charge the iron ore having a wide particle size distribution to perform the pre-reduction.

Although two examples have been introduced above, the present invention can also be implemented as follows.

A) It is also possible to reduce the ore only by the reducing furnace according to the invention (Claim 1) without using it together with other reducing furnaces such as a smelting reducing furnace. In that case, a reducing gas supply source is required separately, but if the composition, temperature, and amount of the gas, ore retention time in the furnace, etc. are set appropriately,
This is because the ore in the solid state can be completely reduced.

B) The reducing furnace and the reducing apparatus of the invention (claims 1 and 2) are not limited to the case where pig iron is obtained from iron ore as a raw material, and ferroalloy or the like is obtained from other metal oxide ores. Also applicable for.

[0032]

The ore reduction furnace according to the present invention (Claim 1) has the following effects.

1) Since the temperature of the reducing gas passing through the gas introduction pipe becomes lower than in the conventional case, the lower part of the furnace such as the pipe and the rectifying nozzle can be easily constructed, and the burden of maintenance such as cleaning is reduced. Naturally, the lower the maintenance frequency, the higher the operating rate.

2) Since the raw ore charging equipment can be arranged at a low position, the equipment cost related thereto can be reduced.

3) Since the diameter of the gas introduction pipe is small, the space occupied by the furnace can be reduced.

4) Since the ore is preheated before it reaches the fluidized bed, the ore retention time in the fluidized bed can be shortened and the production efficiency can be improved.

In addition to the above, the ore reducing apparatus according to the present invention (claim 2) has the following effects.

5) As a reducing gas in the preliminary reducing furnace, the dust contained in the gas is used in the preliminary reducing furnace even though the gas generated in the reducing furnace (which is different from the preliminary reducing furnace) is used. Since it does not easily adhere to or accumulate on the gas introduction pipes and rectifying nozzles, the maintenance burden is also reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention and showing an outline of an ore reduction apparatus having two reduction furnaces including a preliminary reduction furnace, and a smelting reduction system as a whole.

FIG. 2 is a vertical sectional view of a reduction furnace (preliminary reduction furnace) according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing a conventional smelting reduction system.

[Explanation of symbols]

 10/30 Pre-reduction furnace 11/31 Gas inlet pipe 12 / 32a Rectifying nozzle 32 Dispersion plate 13a / 33a Fluidized bed 19 / 39A Input port 20 Melt reduction furnace (another reduction furnace)

Front Page Continuation (72) Inventor Satoshi Tatsuda 3-1-1 Higashikawasaki-cho, Chuo-ku, Kobe-shi, Hyogo Prefecture Kawasaki Heavy Industries, Ltd. Kobe factory

Claims (2)

[Claims] 1. A reduction furnace for ores that fluidizes and reduces metal oxide ore on the nozzle by sending a reducing gas from a gas introduction pipe at the lower part of the furnace to an upper part of the furnace through a rectifying nozzle. In addition, an inlet for ore as a raw material is provided in the gas introduction pipe, and the opening size and inner material of the pipe and the shape and opening size of the rectifying nozzle are reduced from the input position to the nozzle. An ore reduction furnace characterized by being set to transport ore on gas. 2. An ore reduction furnace according to claim 1 is used as a preliminary reduction furnace together with another reduction furnace, and the ore as a raw material is supplied to the preliminary reduction furnace as a reducing gas. An ore reduction device characterized in that it is carried on the generated gas, transported to a preliminary reduction furnace, then subjected to preliminary reduction, and the ore is charged into another reduction furnace for final reduction.