JPH0463216A - Smelting reduction device - Google Patents

Abstract

PURPOSE:To improve the efficiency of production by connecting the bottom of the wind box of a prereduction furnace and the upper part of a smelting reduction furnace by a pipeline and providing an opening adjusting damper on the exhaust gas pipe of the prereduction furnace. CONSTITUTION:The smelting reduction device for metals is provided with the smelting reduction furnace 2 and the fluidized bed type prereduction furnace 1 into which the gas generated in the smelting reduction furnace is introduced as a reducing gas from the lower wind box 16 and which brings the gas into contact with metal oxide ore and discharges the gas from the exhaust gas pipe 4 in the upper part. The bottom of the wind box 1b of the prereduction furnace 1 and the upper part of the smelting reduction furnace 2 are, thereupon, connected by the pipeline 3 in common use as the passage for the metal oxide ore from the former to the latter and the passage for the gas from the latter to the former. An opening degree adjusting damper 5 is provided on the exhaust gas pipe 14 of the prereduction furnace 1. The charging temp. of the prereduced iron to the smelting reduction furnace is increased in this way and the thermal efficiency is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a preliminary reduction furnace that preliminarily reduces metal oxide ore in a solid state, and a smelting reduction furnace that further melts the ore for final reduction. The present invention relates to a melting reduction apparatus comprising: In the detailed explanation section below, iron (iron ore) will be described as an example of the metal (metal oxide ore).

[Prior Art] The smelting reduction ironmaking method is a method of reducing iron ore in a molten state using a smelting reduction furnace to obtain pig iron.

Although smelting reduction furnaces have the advantage of rapid reaction and the ability to flexibly adjust production volume, they have a low energy utilization rate, so smelting reduction equipment is often configured by adding a preliminary reduction furnace to the furnace. . The gas generated in the smelting reduction furnace (a high-temperature reducing gas containing Co) is introduced as a reducing gas into the pre-reduction furnace, where the iron ore is preliminarily reduced in a solid state (to pre-reduced iron). After that, it is charged into a smelting reduction furnace. As the pre-reduction furnace, a fluidized bed type is often adopted in which iron ore is reduced while being fluidized by the above-mentioned reducing gas. This is because the fluidized bed method allows granular iron ore to be used as it is as a raw material and can be processed continuously and uniformly.

Conventionally, a smelting reduction furnace and a fluidized bed pre-reduction furnace are connected as shown in FIG. That is, a supply pipe 7 for pre-reduced iron (iron ore) is provided from the fluidized bed chamber 1c of the pre-reduction furnace 1 to the upper part of the smelting-reduction furnace 2 located below, and from the hood 2e of the smelting-reduction furnace 2 to the pre-reduction furnace. The gas duct 9 is continuous up to the wind box (gas introduction chamber) 1b.

The path for the pre-reduced iron from the pre-reduction furnace 1 to the smelting reduction furnace 2 and the path for the reducing gas flowing in the opposite direction are separate pipes. This point is also the same in the device described in Japanese Patent Application Laid-Open No. 1-152225. In addition, in detail, in the middle of the supply pipe 7, there is a powder cutter (for example, a rotary valve) 8a, 8 that has a function of maintaining the pressure difference between the upper and lower sides.
A preliminary reduced iron dispensing means 8 consisting of a buffer tank 8b and a buffer tank 8b must be interposed.

[Problems to be Solved by the Invention] Although the smelting reduction apparatus as shown in FIG. 4 has the advantage of being easy to control the amount of pre-reduced iron supplied to the smelting reduction furnace 2, it has the following disadvantages.

b) There is a considerable pressure difference between the inside of the fluidized bed chamber la of the preliminary reduction furnace 1, where the upper end of the supply pipe 7 is open, and the inside of the smelting reduction furnace 2, where the lower end is open (the latter is higher) So,
The above-mentioned dispensing means 8 is essential in order to send the preliminary reduced iron from the former to the latter.

Providing the means 8 has the disadvantage of increasing the overall height of the melting reduction apparatus, not to mention the cost disadvantage.

) While passing through the supply pipe 7 (and dispensing means 8),
Heat is radiated from the preliminary reduced iron to the outside of the system (into the atmosphere), so
Accordingly, the thermal efficiency as a melting reduction device is low.

c) Dust (such as iron powder) generated together with the gas from the melting reduction furnace 2 tends to adhere and accumulate on the inner surface of the duct 9. This is partly because the inner surface of the duct 9 is lined with refractory material in order to keep the gas warm and its reducing ability high.

2) To prevent the pre-reduced iron from falling from the fluidized bed chamber 1c through the nozzle of the dispersion plate (gas rectifying plate) la,
It is common sense to introduce a large amount of reducing gas into the preliminary reduction furnace 1, but even in that case, some preliminary reduced iron falls and accumulates in the wind box 1b. They are welded by being exposed to the high temperature reducing gas at the bottom of the wind box 1b for a long time, and become deposits that are extremely difficult to remove.

An object of the present invention is to provide a melting reduction apparatus that eliminates the above-mentioned disadvantages (a) to (2).

[Means for Solving the Problems] In the smelting reduction apparatus according to claim 1 of the present invention, (1) the bottom of the wind box of the preliminary reduction furnace and the upper part of the smelting reduction furnace are connected to the iron ore (preliminary reduced iron) from the former to the latter; The passageway is connected by a pipe that also serves as a passageway for reducing gas from the latter to the former, and an opening adjustment damper is provided on the exhaust gas pipe of the preliminary reduction furnace.

In addition, in the smelting reduction apparatus of claim 2, (1) the bottom of the wind box of the preliminary reduction furnace and the top of the smelting reduction furnace are connected to a passage for iron ore (preliminary reduced iron) from the former to the latter and a passage for reducing gas from the latter to the former; They are connected by a pipe that also serves as a passage, and a gas vent pipe with an opening adjustment damper is connected to the wind box of the preliminary reduction furnace or the upper part of the smelting reduction furnace.

[Function] In the smelting reduction apparatus of this invention, the pre-reduced iron falls into the wind box in the pre-reduction furnace, and the pre-reduced iron is supplied from the bottom of the box to the smelting-reduction furnace through the pipe line (2) above. Reducing gas is led in the opposite direction (from the latter to the former) through the same conduit. In other words, the pre-reduced iron that has fallen into the wind box in the pre-reduction furnace falls by gravity in the direction opposite to the flow of the gas while coming into contact with the reducing gas in the above-mentioned pipe and enters the smelting reduction furnace. . Since the reducing gas from the smelting reduction furnace has a high temperature, the pre-reduced iron continues to be pre-reduced while being heated in this conduit. Further, dust carried by gas from the smelting reduction furnace and attached to the inner surface of the pipe line is removed by the preliminary reduced iron moving downward, and falls into the smelting reduction furnace together with the preliminary reduced iron.

The amount of pre-reduced iron supplied to the smelting reduction furnace is adjusted by appropriately setting the opening degree of the opening adjustment damper of the above (claim 1) or ◎ (claim 2). The pre-reduced iron supplied to the smelting reduction furnace is the one that falls from the fluidized bed chamber to the wind box in the pre-reduction furnace, and the amount of pre-reduced iron that leaves the smelter reduction furnace, passes through the wind box of the pre-reduction furnace and rises. This is because the amount of reducing gas flowing into the fluidized bed chamber can be adjusted. That is, in the case of claim 1, when the opening degree of the damper (2) is increased, the pressure of the gas in the pre-reduction furnace decreases, the volume increases, and the actual flow of gas into the fluidized bed j! (flow velocity) increases, and the amount of falling preliminary reduced iron (that is, the amount of supply) decreases. In the case of claim 2, for example, when the opening degree of the damper (■) is increased, the amount of gas flowing from the gas vent pipe to the outside increases, and the amount of gas flowing into the fluidized bed chamber of the pre-reducing furnace decreases, thereby reducing the amount of pre-reduced iron that falls. (supply amount) increases.

In this way, by adjusting the amount of gas that reaches the fluidized bed chamber of the pre-reduction furnace, the pre-reduced iron is allowed to fall by gravity and is supplied to the smelting reduction furnace. Therefore, the means for discharging the pre-reduced iron to the smelting reduction furnace is specially designed. It's not necessary.

[Example] FIG. 1 is a schematic cross-sectional view of a melting reduction apparatus as a first example of the present invention. In the figure, reference numeral 1 indicates a fluidized bed preliminary reduction furnace for iron ore, and reference numeral 2 indicates a smelting reduction furnace.

The preliminary reduction furnace 1 includes a dispersion plate 1a in which a large number of nozzles are drilled.
A wind box 1b is formed in the lower part of the furnace body, and a fluidized bed chamber 1c is formed in the upper part. In the fluidized bed chamber 1c,
While granular iron ore is introduced from the input pipe 1d, the wind box 1
Reducing gas (also fluidizing gas) is introduced from b through (the nozzle of) the dispersion plate 1a, and the iron ore is fluidized while being heated and reduced to become pre-reduced iron. An exhaust gas pipe 4 is provided in the upper part of the fluidized bed chamber 1c, and a cyclone 6a for collecting scattered fine particles of pre-reduced iron is interposed therein, and a cut-out valve 6b and a transfer pipe 6c are connected to the exhaust gas pipe 4.
or connected.

The smelting reduction furnace 2 obtains molten pig iron by charging preliminary reduced iron, coal as a reducing agent, oxygen as a combustion agent, etc. into an iron bath (molten iron) 2a. In the figure, reference numeral 2b is a charging pipe for coal and auxiliary raw materials, 2c is a lance for oxygen blowing, and 2d is a blowing pipe into which fine particles of preliminary reduced iron collected by the cyclone 6a are charged together with the iron bath stirring gas. be. During operation, high-temperature reducing gas containing a large amount of CO (-carbon oxide) is generated from the iron bath 2a. This is collected in a closed hood 2e and sent to the preliminary reduction furnace 1 as a reducing gas. ing. Reference numeral 2f is a part of support means that supports the melting reduction furnace 2 in a tiltable manner.

In this device, a conduit 3 serves both as an introduction path for gas from the smelting reduction furnace 2 to the preliminary reduction furnace 1 and as a supply path for preliminary reduced iron from the preliminary reduction furnace 1 to the smelting reduction furnace 2.・2 is connected. Since this pipe line 3 is a passage for reducing gas, it is connected to the hood 2e of the melting reduction furnace 2 and the wind fib of the preliminary reduction furnace l.
It was lined with refractory material to suppress the heat radiation of the gas.

Since the conduit 3 is also a passage for the pre-reduced iron, it should be opened wide at the center of the bottom of the wind box 1b to prevent the pre-reduced iron from accumulating in the wind box 1b, and should be opened sufficiently steeply so that the pre-reduced iron can fall by gravity. It was tilted. In addition, the dispersion plate 1 of the preliminary reduction furnace 1
Regarding a, a straight nozzle with a diameter larger than the particle size of the iron ore is provided so that the preliminary reduced iron in the fluidized bed chamber 1c passes through this and falls into the wind box 1b and the pipe line 3. There is. Such a nozzle is also advantageous in that although iron ore tends to sinter or weld at high temperatures, it is unlikely to be clogged by this.

The amount of pre-reduced iron that passes downward through the distribution plate 1a, that is, the amount that is supplied to the melting reduction furnace 2 via the wind box 1b and pipe line 3, is determined by the flow rate of the gas that passes upward through the distribution plate 1a. In this embodiment, as a means for adjusting the flow rate, a damper 5 whose opening degree can be adjusted is interposed in the exhaust gas pipe 4 from the preliminary reduction furnace 1.

The damper 5 used here has a valve body that is driven to open and close by a remotely controlled actuator (not shown).
The gas pressure inside the preliminary reduction furnace 1 can be changed depending on the opening degree. Therefore, for example, if the opening degree is lowered (closed), the pressure increases and the volume of gas decreases, and the gas flow rate through the dispersion plate 1a decreases, so it is possible to increase the amount of pre-reduced iron that falls. Incidentally, the increase or decrease in the falling amount may be determined, for example, by observing (or automatically detecting) the height of the fluidized bed (bed height) in the fluidized bed chamber 1c in the preliminary reduction furnace 1, and setting it accordingly.

FIG. 2 is a schematic diagram showing a second embodiment of the present invention. In this smelting reduction apparatus, the pre-reducing furnace 1 and the smelting-reducing furnace 2
However, two pre-reduction furnaces 1 are connected in parallel to the smelting reduction furnace 2 using a bifurcated pipe line 3. Further, an exhaust gas pipe 4 is connected to each preliminary reduction furnace 1 via an opening adjustment damper 5.

In the apparatus of this embodiment, the amount of preliminary reduced iron supplied to the smelting reduction furnace 2 can be set independently for each preliminary reduction furnace 1. For example, in the past, one pre-reducing furnace 1 supplied a large amount of pre-reduced iron to the smelting reduction furnace 2, while the other pre-reducing furnace 1 reduced its supply amount to almost zero, and over time the degree of reduction (pre-reduced iron) was reduced to zero. It is also possible to increase the return rate.

The subsequent smelting reduction apparatus shown in FIG. 3 is a third embodiment of the present invention, in which a pre-reducing furnace, a smelting-reducing furnace, and a conduit between the two, that is, a dual-purpose passage for pre-reduced iron and reducing gas, are integrated into one furnace body. It was formed in a composite furnace 10.

That is, the illustrated combined furnace 10 having a vertically long cylindrical furnace body
A fluidized bed pre-reduction furnace section 11 was provided in the upper part, and a smelting reduction furnace section 12 was provided in the lower part.

The preliminary reduction furnace section 11 has a fluidized bed chamber 11C on the top and a wind box 11b on the bottom with a dispersion plate 11a in between, and an iron ore input pipe lid and an exhaust gas pipe 14 are provided at the top. be. In addition, regarding the melting reduction furnace section 12, the bottom part is an iron bath holding section 12a, and here is provided a blowing pipe 12c for oxygen and fine powder raw materials, and a tapping hole 12g that can be opened and closed using a mud gun, an air drill, etc. A charging pipe 12b for coal, etc., and a nitrogen gas blowing pipe 12h for temperature adjustment (cooling) of the gas sent to the preliminary reduction furnace section 11 are connected to the side wall. Since both furnace parts 11 and 12 are connected vertically in a straight line, the space directly below the preliminary reduction furnace part 11 is a wind box 11b, and at the same time, the space that falls from the dispersion plate 11a is connected to the smelting reduction furnace part 12. It is also a conduit 13 through which both the preliminary reduced iron leading to the smelting reduction furnace section 12 and the reducing gas generated in the smelting reduction furnace section 12 and heading toward the preliminary reduction furnace section 11 pass.

In such a combined furnace IO, an opening adjustment damper 15 is provided on the exhaust gas pipe 14 of the preliminary reduction furnace section 11, and on the side wall of the wind box 11b, that is, the upper space of the smelting reduction furnace section 12, which is also the pipe line 13. A gas vent pipe 16 having an opening adjustment damper 17 is connected. All of these fall from the pre-reduction furnace section 11 and enter the smelting reduction furnace section 12.
This is a means to adjust the amount of preliminary reduced iron supplied to the That is, the damper 15 is the same as the damper 5 in the embodiment described above.
Similarly, by changing the pressure inside the furnace, the distribution plate 11a
Adjust the amount of pre-reduced iron falling by changing the gas flow rate through. The gas vent pipe 16 and the damper 17 bypass a part of the gas generated in the melting reduction furnace section 12 to the downstream of the exhaust gas pipe 4 without sending it to the preliminary reduction furnace section 11, thereby reducing the amount of gas passing through the distribution plate 11a. It is possible to adjust the flow rate and therefore the falling amount of pre-reduced iron.

The reason why two means for adjusting the fall amount of preliminary reduced iron are provided as described above is that by simultaneously adjusting the opening of the two dampers 15 and 17, the gas pressure in the furnace and the gas flow rate passing through the dispersion plate 11a can be adjusted separately. The purpose is to make it possible to adjust the falling amount of preliminary reduced iron with a high degree of freedom. For example, when the opening degree of the damper 15 is lowered (squeezed), the gas flow rate decreases and the gas pressure increases, but at the same time, the damper 17
By increasing the opening degree appropriately, the pressure can be returned to its original constant value. This is an advantage because the gas pressure affects the metallurgical reactions inside the furnace. Compared to this example (Fig. 3), even if there is no damper 15, or there is a damper 15, the gas vent pipe 16 and the damper 17
Needless to say, it is possible to adjust the fall amount of the preliminary reduced iron even if there is no such thing.

Although this combined furnace 10 is a fixed (stationary) type furnace and does not have a tilting means, the furnace body can be separated by several flanges (not shown) for convenience such as installing refractories inside. is joined to.

Above, three embodiments have been introduced, and in addition to these, various embodiments of the present invention can be considered, for example, as described below.

a) The fluidized bed pre-reduction furnace may not include a dispersion plate, but instead may have a smaller diameter at the boundary between the wind box and the fluidized bed chamber.

b) Not only equipment for obtaining pig iron using iron ore as raw material, but also ferroalloys from other metal oxide ores, etc.
It can also be applied as a melting reduction device for obtaining etc.

[Effects of the Invention] The melting reduction apparatus of the present invention (claims 1 and 2) has the following effects.

b) It is possible to send pre-reduced iron (iron ore) from the pre-reduction furnace to the smelting reduction furnace without providing any special discharging means.

(1) The pre-reduced iron that has left the pre-reduction furnace continues to be heated and reduced by contacting high-temperature reducing gas in the same conduit to the smelting-reduction furnace, so the temperature at which it is introduced into the smelting-reduction furnace becomes high. Thermal dynamics ↑ or improved. Furthermore, for the same reason, the time the iron ore must stay in the preliminary reduction furnace can be shortened, leading to more efficient production.

c) Dust generated from the smelting reduction furnace adheres and accumulates in the gas passage (pipe line of the present invention) to the preliminary reduction furnace.

2) The pre-reduced iron that falls into the wind box in the pre-reduction furnace reaches the smelting reduction furnace through a pipe and does not accumulate at the bottom of the wind box, so it can be removed even if the operation continues for a long time. There is no need to do this.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a melting reduction apparatus as a first embodiment of the present invention. Also, Figures 2 and 3
The figures are a front view and a sectional view showing second and third embodiments of the present invention, respectively. On the other hand, FIG. 4 is a sectional view of a conventional melt reduction apparatus. l・Preliminary reduction furnace, lb・・wind box, 2・・melting reduction furnace,
3. Pipe line, 4. Exhaust gas pipe, 5. Opening adjustment tamper 1
0. Combined furnace, 11. Preliminary reduction furnace part, 12. Melting reduction furnace part, 14. Exhaust gas pipe, 15. 17. Opening adjustment tamper 16. Gas venting pipe.

Claims (1)

[Claims] 1. A smelting reduction furnace, and a fluidized bed pre-reduction furnace in which the generated gas is introduced as a reducing gas from a lower wind box, brought into contact with metal oxide ore, and then discharged from an upper exhaust gas pipe. (a) The bottom of the wind box of the pre-reduction furnace and the upper part of the smelting reduction furnace are connected to a passage for metal oxide ore from the former to the latter and a passage for the gas from the latter to the former. A smelting reduction apparatus characterized in that it is connected by a pipe line that also serves as a passage, and (b) an opening adjustment damper is provided in the exhaust gas pipe of the preliminary reduction furnace. 2. Melting reduction of metals equipped with a smelting reduction furnace and a fluidized bed pre-reduction furnace in which the generated gas is introduced as a reducing gas from a lower wind box, brought into contact with metal oxide ore, and then discharged from an upper exhaust gas pipe. In the apparatus, (a) a conduit connecting the bottom of the wind box of the preliminary reduction furnace and the top of the smelting reduction furnace, which serves as a passage for metal oxide ore from the former to the latter and a passage for the above gas from the latter to the former; (c) A gas venting pipe having an opening adjustment damper is connected to the wind box of the preliminary reduction furnace or the upper part of the melting reduction furnace.