JPH01247522A - Apparatus for recovering reduced iron powder in iron ore pre-reducing apparatus - Google Patents

Abstract

PURPOSE:To improve the recovery ratio of reduced iron powder and the yield of reducing ore by recovering reduced iron powder contained in exhaust gas from a fluidized bed pre-reducing furnace with a cyclone and a filtration device using ceramic filter at the rear step of the cyclone. CONSTITUTION:In smelting reduction apparatus, the cyclone 10 is set at outlet side of the exhaust gas of the fluidized bed prereducing furnace 6 to catch relatively large particle in the reduced iron powder contained in the exhaust gas. Successively, small particle in the reduced iron powder is caught and recovered with the filtration device 11 using ceramic filter and arranging at the rear step of the cyclone 10. A heat exchanger 12 is set between the filtration device 11 and a dispersing tower 13, and sensible heat in the exhaust gas from the filtration device 11 is recovered. The filtration device 11 has main constructions composing of a can body 31, ceramic porous body 32 fitted in the can body 31, introducing pipe 33 for introducing the exhaust gas from the cyclone 10 and an exhaust pipe 34 for exhausting the exhaust gas after filtrating.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for recovering reduced iron powder generated during the fluid reduction process of powdery granular iron ore.

[Conventional technology]

In recent years, smelting reduction equipment has been attracting attention as equipment for reducing iron ore to produce hot metal. This melting reduction equipment is
It was developed with the aim of producing molten iron-based alloys using smaller-scale equipment without being restricted by the raw materials used.

As one such melting reduction equipment, the present inventors have
Previously, we proposed a facility constructed with the flow shown in Figure 5 in Japanese Patent Application No. 71562/1983.

In this facility, hot metal is produced in the following manner. That is, iron manufacturing raw materials such as granular iron ore 19 and limestone 2 are charged from hoppers 1a and 2a into an exhaust gas flue 21 extending from a fluidized bed preheating furnace 5, and sent to a cyclone 23 via a pipe 22. During this conveyance process, the exhaust gas flue 21
After being heated while exchanging heat with the exhaust gas sent from the cyclone 23, it is separated from the exhaust gas and sent to the fluidized bed preheating furnace 5
will be put into the

Coal 3 is charged into the fluidized bed preheating furnace 5 via a hopper 3a, and combustion air 4 is fed from the hearth. This air 4 causes fluidized combustion of the introduced coal 3, and maintains the temperature of the fluidized bed in the fluidized bed preheating furnace 5 in the range of 600 to 1000°C. In such an atmosphere, the input raw materials such as iron ore 11 and limestone 2 are preheated and roasted.

The preheated mixture of iron ore, lime, etc. discharged from the fluidized bed preheating furnace 5 is charged into the fluidized bed prereduction furnace 6. In addition, in the same figure, the reference numeral 24 is a 2 μm machita feeder.

A high-temperature reducing gas 8 of about 1000° C. discharged from the melting reduction furnace 7 is blown into the fluidized bed pre-reduction furnace 6 through the lower part of the furnace. By this reducing gas 8, raw materials such as iron ore sent from the fluidized bed preheating furnace 5 are floated and fluidized in the fluidized bed preheating furnace 6, and the carbon contained in the reducing gas 8 is
It is pre-reduced by O, H2, etc.

Here, in order to recover the reduced iron powder scattered outside from the fluidized bed preliminary reduction furnace 6 and return it to the fluidized bed preliminary reduction furnace 6, a particle circulation device 25 is provided in the upper part of the fluidized bed preliminary reduction furnace 6. There is. As this particle circulation device 25, for example, as shown in the figure, a multi-stage cyclone 25a is used.
A combination of the hopper 25b and the hopper 25b is used. Note that numerals 25c, 25d, and 25e in the figure indicate new ivy feeders. Final stage fluidized bed pre-reduction furnace 6
The reduced iron powder recovered by the particle circulation device 25 attached to the sintering device 2 is sent to the melting reduction furnace 7 via the conveyance path 26.

The reduced ore cut out from the lower part of the fluidized bed of the fluidized bed pre-reduction furnace 6 is fed into the smelting reduction furnace 7 via the conveyance path 27.

In this melting reduction furnace 7, oxygen 9 is blown toward the iron bath 20 from a top blowing lance (not shown), and oxygen 9 and carbonaceous material are blown into the iron bath 20 from a bottom blowing tuyere (not shown). . The reduced ore charged into the smelting reduction furnace 7 is melted in the smelting reduction furnace 7, and the reduction progresses to become hot metal.

By the way, in the above-mentioned smelting reduction equipment, there is an improvement for recovering reduced iron powder generated during the reduction process in the fluidized bed pre-reduction furnace 6 and contained in the gas discharged from the fluidized bed pre-reduction furnace 6. A recovery device as shown in FIG. 6 or FIG. 7 is used as a recovery device.

The apparatus shown in FIG. 6 has a cyclone 51 and a bag filter 52 installed in the middle of the gas discharge path of the fluidized bed pre-reduction furnace 6, and the cyclone 51 collects relatively large reduced iron powder, and the bag filter 52 collects a relatively large amount of reduced iron powder. It collects small particles of reduced iron powder. The recovered reduced iron powder is sent to the melting reduction furnace 7, and the exhaust gas is diffused from the diffusion tower 54.

The apparatus shown in FIG. 7 has a cyclone 51 and a wet dust collector 55 installed in the middle of the gas discharge path of the fluidized bed preliminary reduction furnace 6, and collects relatively large reduced iron powder with the cyclone 51.
The wet dust collector 55 collects small particles of reduced iron powder. The reduced iron powder recovered by the cyclone 51 is sent to the smelting reduction furnace 7, and the reduced iron powder recovered by the wet dust collector 55 is separated from water by the thickener 56, dehydrated by the dehydrator 57, and then subjected to fluidized bed preliminary reduction. It is sent to the furnace 6 as a raw material. The exhaust gas is diffused from the diffusion tower 54.

[Problem to be solved by the invention]

However, these reduced iron powder recovery devices still have the following problems. That is, in the apparatus shown in FIG. 6, since the allowable heat-resistant temperature of the bag filter 52 is as low as about 200°C, it is necessary to keep the exhaust gas temperature at the inlet side of the bag filter 52 below about 200°C. As shown in FIG. 6, a heat exchanger 53 is installed between the cyclone 51 and the bag filter 52 to lower the temperature of the exhaust gas before passing it through the bag filter 52. However, when the heat exchanger 53 is installed between the cyclone 51 and the bag filter 52, the exhaust gas still contains a large amount of reduced iron powder, so the iron powder adheres to the inner walls of the heat exchanger tubes. In addition, there is a problem that the heat transfer coefficient is low (and the recovery rate of exhaust gas sensible heat is low.In addition, if the heat exchanger 53 is not installed, the exhaust gas temperature must be lowered by a separate cooling means. bag filter 5
2, but in this case, the sensible heat of the exhaust gas is hardly recovered.

In addition, in the device shown in Figure 7, there is no problem with the heat resistance temperature because it is a wet dust collector, but since the reduced iron powder is recovered together with water, the iron powder comes into contact with water and the atmosphere and oxidizes again, causing iron ore to be removed. Like stone powder, it can only be used as a raw material for the fluidized bed pre-reduction furnace 6. Also, thickener 56. Dehydrator57. Since a molding machine (not shown) and the like are required, the cost of these equipment increases, and there is also the problem that the sensible heat of the exhaust gas cannot be recovered.

Therefore, an object of the present invention is to improve both the recovery rate of reduced iron powder and the recovery rate of exhaust gas sensible heat by recovering reduced iron powder from high-temperature exhaust gas in an iron ore preliminary reduction device.

[Means to solve the problem]

In order to achieve the purpose of the reduced iron powder recovery device of the iron ore pre-reduction device of the present invention, a cyclone is provided on the exhaust gas outlet side of the fluidized bed pre-reduction furnace of the iron ore pre-reduction device in the smelting reduction equipment. It is characterized by a filtration device using a ceramic filter installed downstream of the cyclone.

Here, as the ceramic filter, a tubular porous body made by molding and firing ceramic particles into a tubular shape, or a tubular vA vertebral body made by laminating ceramic fibers in a tubular shape can be used.

[Effect]

In the present invention, relatively large particles of reduced iron powder contained in the exhaust gas from the fluidized bed pre-reduction furnace are collected by a cyclone, and small particles are collected by a filtration device using a ceramic filter. to recover.

The heat resistance temperature of ordinary ceramic compacts or ceramic fibers is higher than 1000°C, while the temperature of the exhaust gas from the fluidized bed pre-reduction furnace is below 1000°C.
In a filtration device using a ceramic filter, the reduced iron powder contained therein can be recovered by allowing the high-temperature exhaust gas to pass through as it is. The entire amount of the recovered reduced iron powder can be supplied to the melting reduction furnace. Further, since the exhaust gas remains at a high temperature after leaving the filter, the heat recovery rate can be increased by recovering sensible heat using a heat exchanger.

〔Example〕

Hereinafter, the features of the present invention will be specifically explained using examples with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a melting reduction facility according to an embodiment of the present invention. In this figure, the same devices as those shown in FIG. 5 are designated with the same reference numerals.

In this embodiment, a cyclone 10 is installed on the exhaust gas outlet side of the fluidized bed preliminary reduction furnace 6, and a filtration device 1 using a ceramic filter is installed on the exhaust gas outlet side of the cyclone 10.
1 is installed. Then, the filtration device 11 and the stripping tower 13
A heat exchanger 12 is installed between them to recover the sensible heat of the exhaust gas from the filtration device 11.

Here, cyclone 10 is cyclone 5 described in FIG.
This cyclone 10 is a device similar to No. 1, and this cyclone 10 collects reduced iron powder having a particle size of about 0.3 mm or more.

The filtration device 11 has a built-in ceramic filter and is a device for recovering small reduced iron powder that could not be recovered by the cyclone 10.

As the ceramic filter used in the filtration device 11,
For example, a tubular porous body (
(hereinafter referred to as a ceramic porous body) can be used. Also, for example, a tubular u! i
A vertebral body (hereinafter referred to as a ceramic fiber body) can also be used.

FIG. 2 is a schematic cross-sectional view showing a structural example of a filter device 11 using a ceramic porous body as a ceramic filter.

The filtration device 11 includes a can body 31 , a ceramic porous body 32 attached to the can body 31 , an introduction pipe 33 for introducing exhaust gas from the cyclone 10 into the can body 31 , and the ceramic porous body 32 The main structure is a discharge pipe 34 for discharging the filtered gas.

The ceramic porous body 32 is made by, for example, forming homogeneous cordierite particles into a tube shape and firing the tube at a high temperature. In this example, the outer diameter is 170 mm.

A porous body consisting of three short tubes each having an inner diameter of 140 mm and a length of 1500 mm connected in the tube axis direction with a connector 35 is supported at the upper part by a supporter 36 and at the lower part by a partition plate 37 to form a can body. Installed in 31. Note that a plurality of ceramic porous bodies 32 can be provided in parallel depending on the size of the can body 31. Furthermore, in this embodiment, the ceramic porous body 32 has a two-layer structure of a base material and a filter material. Then, the inner surface of the ceramic porous body 32 is used as a filter material with a pore diameter of several micrometers, and the outer surface has a pore diameter of 100 to 200 μ! It was used as a base material of n. In the case of this embodiment, the exhaust gas from the cyclone 10 is passed through the ceramic porous body 3 from the lower part of the introduction pipe 33.
2, passes through the filter material and base material of the ceramic porous body 32, and is discharged from the discharge pipe 34. Then, when the gas passes through the filtering material of the ceramic porous body 32, the contained reduced iron powder is filtered out. Here, if gas filtration is performed continuously, the amount of reduced iron powder attached to the inner surface of the ceramic porous body 32 increases with the passage of time. Therefore, at appropriate time intervals, the ceramic porous body 32
backwash. In this backwashing operation, high-pressure nitrogen gas is injected from the gas header 38 into the can body 31 for a short period of time (within 1 second), for example, at intervals of 6 to 20 minutes.

Due to the injection of this backwashing gas, the reduced iron powder adhering to the filter surface falls downward. The fallen reduced iron powder 39 is supplied to the smelting reduction furnace 7 through a conveyance path (not shown).

Note that the filtration device 11 shown in FIG. 2 is of a type that filters gas by passing it from the inside of the tubular ceramic porous body 32 to the outside. It is also possible to filter the gas by passing it from the outside to the inside. In this case, the ceramic porous body 3
The outer surface of the ceramic porous body 32 is used as a filter material, and the inner surface is used as a base material, and the gas introduced from the introduction pipe 33 in FIG. The filtered gas is discharged from an exhaust pipe connected to the upper part of the ceramic porous body 32. In backwashing, nitrogen gas is injected into the ceramic porous body 32 from above the ceramic porous body 32 .

FIG. 3 is a perspective view showing the ceramic fiber body, and FIG. 4 is a perspective view showing the arrangement state of the ceramic fiber body.

As shown in FIG. 3, the ceramic fiber body 41 is a blanket-like body made of laminated ceramic fibers formed into a cylindrical shape using a support frame 42 made of stainless steel, for example. As shown in FIG. 4, an appropriate number of connected long or short ceramic fiber bodies 41 are installed in parallel inside a can body (see FIG. 2) using a support 43 or the like. . Note that 44 in the figure is a backwashing gas pipe.

When using the ceramic porous body 32 or the ceramic fiber body 41 as a filter in the filtration device 11,
Since the ceramic has a heat resistance temperature of 1000° C. or more, the exhaust gas from the cyclone 10 can be passed through the filtration device 11 at a high temperature without being cooled. For this reason, the recovery rate of reduced iron powder is as high as that of conventional bag filters, and it is possible to obtain a filtration device 11 with less dust in the gas finally emitted from the dispersion tower 13.Moreover, the lifespan of the ceramic filter is It is several times to ten times longer than a conventional bag filter, and the running cost of the filtration device 11 is also reduced.Furthermore, after the reduced iron powder is recovered in the filtration device 11, the heat exchanger 12 is used to collect the exhaust gas. Since heat is recovered, there is no clogging of the heat exchanger tubes of the heat exchanger 12, the heat recovery rate is high, and an iron ore pre-reduction device with high overall thermal efficiency can be obtained.

〔Effect of the invention〕

As explained above, in the iron ore pre-reduction apparatus of the present invention, the reduced iron powder contained in the exhaust gas from the fluidized bed pre-reduction furnace is removed by a filtration device using a cyclone and a ceramic filter installed after the cyclone. It is now possible to collect it by Therefore, reduced iron powder can be recovered at a high recovery rate similar to that of the conventional dry dust collection method, and the yield of reduced ore can be increased. When the heat exchanger recovers the sensible heat of the exhaust gas after recovering the reduced iron powder using the filtration device, the heat exchanger tubes do not become clogged and a high heat recovery rate is obtained. The temperature of the emitted gas can be lowered and the amount of dust in the gas can be reduced. In addition, the life of the filtration device is longer than that of conventional dry dust collection methods, and
By recovering the sensible heat of the exhaust gas, an iron ore pre-reduction device with high overall thermal efficiency can be obtained. Additionally, equipment costs can be significantly reduced compared to conventional wet dust collection methods.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a schematic configuration of a melt reduction equipment according to an embodiment of the present invention, Fig. 2 is a schematic sectional view showing an example of the structure of a filtration device using a ceramic porous body, and Fig. 3 is a diagram showing a ceramic fiber body. FIG. 4 is a perspective view showing the arrangement of the ceramic fiber body, FIG. 5 is a diagram showing an example of the configuration of a conventional smelting reduction equipment, and FIGS. 6 and 7 are a diagram showing a conventional method for recovering reduced iron powder. It is a figure showing an example of a device. 1: Iron ore 2: Limestone 3: Coal 1a, 2a, 3a: Hopper 4: Air 5: Fluidized bed preheating furnace 6: Fluidized bed pre-reduction furnace 7: Melting reduction furnace 8: Reducing gas
9: Oxygen 10: Cyclone 11: Filtration device 12: Heat exchanger 13: Stripping tower 20: Iron bath 2
1: Exhaust gas flue 22: Piping 23: Cyclone 24, 25c, 25d, 25e: = +L
-7 Chick feeder 25: Particle circulation device 25a
: Cyclone 25b: Hopper 26, 27: Conveyance route 3
1: Can body 32: Ceramic porous body 33
:Inlet pipe 34:Outlet pipe 35:Connector
36: Support 37: Partition plate 38: Gas header 39: Reduced iron powder 41: Ceramic fiber body 42: Support frame 43: Support 44: Piping 51: Cyclone 52: Bag filter 53: Heat exchanger 54: Emission tower 55: Wet type dust collector 56: Thickener 57 = Dehydrator Patent applicant Nippon Steel Corporation Representative Director
Masu Kobori (and 2 others) Figure 1 Figure 3-1 to Figure 2 ↓ Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1. A cyclone is provided on the exhaust gas outlet side of the fluidized bed pre-reduction furnace of the iron ore pre-reduction device in the smelting reduction equipment, and a filtration device using a ceramic filter is provided downstream of the cyclone. A reduced iron powder recovery device for an iron ore preliminary reduction device, which is characterized by: 2. A reduced iron powder recovery device for an iron ore preliminary reduction device, wherein the ceramic filter according to claim 1 is a tubular porous body obtained by molding ceramic particles into a tubular shape and firing them. 3. A reduced iron powder recovery device for an iron ore preliminary reduction device, wherein the ceramic filter according to claim 1 is a tubular fibrous body in which ceramic fibers are laminated in a tubular shape.