JPH01242708A - Fluidized-bed reducing equipment for iron ore - Google Patents

Abstract

PURPOSE:To appropriately secure the fluidity in a reducing furnace and to efficiently reduce iron ore by supplying iron ore into the exhaust pipe ot the furnace, sizing the ore by a classifying and preheating cyclone and a solid-gas separation cyclone, and supplying the sized ore into the furnace. CONSTITUTION:The iron ore in a hopper 6 is supplied by a feeder 7a into the exhaust pipe 5 of the fluidized-bed reducing furnace 1, and transported to the classifying and preheating cyclone 2 by the reducing gas discharged from the furnace 1 while being preheated and dried. The coarse iron ore is classified and collected by the cyclone 2, and discharged from a discharger 7c. The iron ore classified to a specified grain size is entrained by the reducing gas, transported to the solid-gas separation cyclone 3, and separated from the reducing gas. The sized iron ore heat-exchanged with the reducing gas, dried, and preheated is sent downward through a transport pipe 8, and supplied to the furnace 1 by a feeder 7b. By this method, good fluidity can be secured in the furnace 1, and the ore is efficiently reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an iron ore reduction apparatus for reducing iron ore for use in a smelting reduction method, a blast furnace method, etc. in a fluidized bed reduction furnace.

[Prior Art] In order to reduce iron ore to produce hot metal, methods such as using a blast furnace and melting iron ore reduced in a shaft furnace in an electric furnace have been adopted.

As an alternative to such conventional hot metal production techniques, the smelting reduction method is attracting attention. The smelting reduction furnace used in this method was developed for the purpose of producing molten metal of iron-based alloys using smaller-scale equipment without being restricted by the raw materials used.

The present applicant previously proposed one of such melt reduction methods in Japanese Patent Application Laid-open No. Sho (IT-64807).

In this type of smelting reduction method, it is clear from the development process that it expands the range of usable raw materials, improves reduction efficiency, promotes the smelting reaction in the smelting reduction furnace, and reduces CO9H2 generated in the smelting reduction furnace. There is a problem in how to effectively utilize the rich reducing gas.

Therefore, from this perspective, the inventors of the present invention have proposed
In the specification of No. 1-288599, one of the particle circulation type iron ore fluidized bed reduction apparatuses was proposed.

FIG. 3 shows the flow.

That is, an external particle circulation device is attached to the fluidized bed reduction furnace, and a cyclone 1 is installed at the outlet provided at the upper part of the fluidized bed reduction furnace 11.
4 is connected to capture the fine particles that are scattered along with the reducing gas 12.

A hopper 15 is connected to the lower part of the cyclone 14 to temporarily store the captured particles, and a predetermined amount of the trapped particles is temporarily stored in the hopper 15 and returned to the fluidized bed reduction furnace 1 by a circulation cutting device IB.

On the other hand, there are a plurality of gas outlets 1 in the fluidized bed reduction furnace 11.
7.18 is formed. This gas outlet 17, 1
A bubbling fluidized bed 19 is formed in the middle of the particle 8, and a circulation outlet of the external particle circulation device is provided within this bubbling fluidized bed 19.

Further, a packed bed 20 is formed at the bottom of the fluidized bed reduction furnace 11, and a bottom blowing nozzle 21 is provided in the packed bed 20.

In the figure, 22 is a cut-off valve for charging the raw material 13 such as fine ore or coal stone into the fluidized bed reduction furnace 11, 23, 24, and 25 are flow control valves for adjusting the amount of reducing gas blown out, and 26 27 is a cut-out valve for fine-grained reduced ore, and 27 is a cut-out valve for fine-grained reduced ore.

Next, raw materials 13 such as fine ore and limestone are charged into the fluidized bed reduction furnace 11 from the cutting valve, and the reducing gas 12 is supplied to the flow rate control valves 23 and 2.
When the gas is blown from the gas outlet 17, 18, 21 through the gas outlet 17, 18, and 25, the air flow from all the gas blowing nozzles is added to the uppermost gas blowing nozzle 17, and the final velocity of the fine raw material particles increases. The velocity is higher than the UL, and the fine raw material particles are scattered above the fluidized bed reduction furnace while reacting with the reducing gas.

The other coarse-grained raw material has a terminal velocity Ut compared to the fine-grained raw material.
Because the gas is large, it does not scatter at the gas outlet 17, and the bubbling fluidized bed 1 located between the two gas outlets 17 and 18
The particles are further air-sieved in step 9, and the coarse particles descend to the packed bed 20 at the bottom of the furnace.

The coarse particles in the packed bed 20 are reliably reduced by a proper flow rate of reducing gas through the furnace bottom blowing nozzle 21 located at the bottom of the furnace, and the coarse reduced ore is discharged from the cutting valve 27 to proceed to the next process. Sent.

On the other hand, the fine particles are scattered in the fluidized bed reduction furnace 11, captured by the cyclone 14 from the outlet at the top of the furnace, and circulated through the bubbling fluidized bed 19 via the hopper 15 and the circulation cutting device 1B, where they are reduced again.

Then, the fine-grain reduced ore that has obtained the desired reduction is removed from the cutting valve 2.
6 and sent to the next process.

[Problems to be Solved by the Invention] However, when iron ore with a wide particle size distribution is used, it is very difficult to ensure fluidity in a fluidized bed reduction furnace, resulting in problems in operability. In other words, if you prevent fine particles from scattering,
The flow of the elementary particles deteriorates or stops, the reduction reactivity of the coarse particles decreases significantly, and problems of aggregation occur.

On the other hand, if the superficial velocity of the reducing gas in the fluidized bed is increased in order to increase the fluidity of coarse particles in order to promote the reduction reaction, the scattering of fine particles from the fluidized bed increases.

For this reason, a particle circulation method is adopted in which scattered particles are collected by a particle collector such as a cyclone and returned to the fluidized bed by a particle circulation device.

In this case, if the particle size distribution is wide, the amount of particles to be circulated becomes enormous, and the circulation device becomes extremely large, which is not rational.

Further, the reduction rate is greatly influenced by the particle size of the ore, and as the particle size increases, the reduction rate decreases significantly.

For this reason, when reducing iron ore with a wide range of particle sizes, uniform reduction is difficult, and the degree of reduction of fine particles is higher than that of coarse particles, resulting in increased adhesion of the reduced ore to each other and agglomeration of fine particles. , or agglomeration into coarse particles, resulting in poor fluidity.
Furthermore, there was a risk of fluidization stoppage trouble occurring.

Therefore, the iron ore to be supplied to the fluidized bed reduction furnace is subjected to a step of drying and sifting in advance, and the sized iron ore is charged, but this dry sifting requires a large amount of equipment.

[Means for Solving the Problems] The iron ore fluidized bed reduction apparatus of the present invention supplies iron ore from an iron ore supply port provided in the middle of an exhaust pipe of a fluidized bed reduction furnace, and removes exhaust gas from the fluidized bed reduction furnace. The iron ore is preheated and dried during the gaseous conveyance process to weaken the cohesive force of the particles and improve separation and classification. The iron ore was divided into predetermined particle sizes and collected using a solid-gas separation cyclone, and the classification preheating cyclone or solid-gas separation cyclone and the fluidized bed reduction furnace were connected through a transfer pipe, and the iron ore was sized to a predetermined particle size. Feed iron ore to the fluidized bed reduction furnace.

In some cases, a gas supply port is provided near the bottom of the classification preheating cyclone, and the gas blown from the gas supply port generates an upflow within the classification preheating cyclone to adjust the size of the classified particles. .

[Function] The iron ore fluidized bed reduction apparatus of the present invention supplies iron ore to the exhaust pipe of a fluidized bed reduction furnace, classifies it to a predetermined particle size using a classification preheating cyclone and a solid-gas separation cyclone, and then converts it into a fluidized bed. Since it is supplied to the reduction furnace, the fluidity of the fluidized bed reduction furnace can be ensured, allowing efficient reduction.

Some iron ore raw materials contain many coarse particles that inhibit flow. When reducing this iron ore, coarse-grained iron ore that is difficult to maintain fluidity in a fluidized bed reduction furnace is separated, and iron ore adjusted to an appropriate particle size is supplied to the fluidized bed reduction furnace.

Therefore, the superficial velocity of the reducing gas in the fluidized bed reduction furnace can be adjusted to an appropriate fluidization speed, the amount of fine iron ore scattering during the fluidization process is small, good fluidity can be ensured, and solid-gas contact can be achieved. Efficiency is improved and efficient returns can be made.

If there is a large amount of iron ore scattered from the fluidized bed reduction furnace,
It is necessary to circulate and supply the particles to the fluidized bed reduction furnace using a particle circulation device, and in some cases, this particle circulation device becomes very large and becomes unreasonable in terms of equipment cost.

In the present invention, since an appropriate fluidization speed can be ensured, the amount of scattering can be reduced, and the particle circulation device can be downsized or omitted. In addition, since iron ore that has been sized and has a uniform particle size is subjected to fluid reduction, the effect of particle size on the reduction rate is small, the reduction rate distribution is sharp, and the controllability of the reduction rate is improved.

Separated coarse-grained iron ore is supplied to the smelting-reduction furnace through a separate route, but it is more efficient to supply coarse-grained iron ore directly to the smelting-reduction furnace and smelting it down than by solid-gas contact in a fluidized bed reduction furnace. Since it can be reduced, the reduction efficiency and productivity of the melting reduction equipment as a whole are improved.

On the other hand, when iron ore containing a large amount of fine particles that are scattered from the fluidized bed is reduced, the fine iron ore that is scattered during the fluidization process is separated and sized.

Therefore, the superficial velocity of the reducing gas in the fluidized bed reduction furnace can be optimized for fluidization, which means that it is unnecessary to reduce the fluidization speed in order to suppress the scattering of fine iron ore in the fluidized bed reduction furnace. Since appropriate fluidization speed can be ensured,
Operability is improved without deteriorating or stopping the flow of coarse iron ore during the flow process.

In addition, since the fine iron ore that is scattered from the fluidized bed is removed in advance, it is possible to increase the superficial velocity, which means that a large amount of reducing gas can be supplied, improving reduction efficiency and productivity. The circulation device can be downsized or omitted.

When iron ore with a wide particle size distribution in which coarse and fine particles are mixed is subjected to fluid reduction without separation, the reduction rate of fine particles is faster than that of coarse particles, so even though the reduction rate of coarse particles is low, First, the reduction rate of the fine particles becomes high, metal iron is generated on the surface of the fine particles, sticking of the reduced ore occurs, deterioration of fluidity, and troubles such as flow stoppage occur.

For this reason, if iron ore with a wide particle size distribution in which coarse particles and fine particles are mixed is subjected to fluid reduction without separation, the average reduction rate must be lowered, but with the present invention, uniform reduction is possible. , the controllability of the reduction rate is improved, and reduction can be achieved to a high reduction rate.

If fine iron ore, which is easily scattered during the fluidized bed process, is reduced in a fluidized bed reduction furnace, a very large particle circulation device is required, which causes problems in reduction efficiency, production, etc.

Therefore, considering that it is better to directly supply the separated fine iron ore to the smelting reduction furnace and smelting and reducing the fine iron ore, since the particles are fine, the reduction reactivity in the smelting reduction furnace is better. It is expected that the reduction efficiency and productivity of the melting reduction equipment as a whole will be improved.

In addition, the iron ore is dried by the exhaust gas of the fluidized bed reduction furnace at 700 to 950°C, while being classified and sized using a classification preheating cyclone and a solid-gas separation cyclone, so that the fine particles that have become pseudo-particles due to moisture are dried. This makes separation easier and improves classification and particle size regulation.

Furthermore, since the iron ore is transported, classified, and preheated by exchanging heat with exhaust gas during the solid-gas separation process, the thermal efficiency of the smelting reduction equipment is improved.

When it is desired to change the particle size distribution of iron ore supplied to the fluidized bed reduction furnace due to the operational status of the fluidized bed reduction furnace, changes in the iron ore raw material, etc., the gas injected from the gas supply port installed near the bottom of the classification preheating cyclone can be changed. This produces an upflow in the classification preheating cyclone and adjusts the classification particle size of the iron ore.

The particle collection limit size is determined by the shape and dimensions of the classification preheating cyclone, but if an upflow occurs within the classification preheating cyclone, the particle collection efficiency of the classification preheating cyclone will deteriorate.
The collection limit particle size becomes larger.

The present invention utilizes this phenomenon to generate upflow within the classification preheating cyclone to adjust the classified particle size of iron ore. This method makes it possible to select the classification particle size, and it is possible to carry out effective classification taking into account the particle size structure, density, etc. of the raw ore.

[Example] The present invention will be explained in detail using an example apparatus shown in FIGS. 1 and 2.

FIG. 1 is a block diagram of a fluidized bed reduction apparatus for fluidized reduction of iron ore containing many coarse particles that inhibit fluidization.

The iron ore stored in the hopper 6 is supplied to the exhaust pipe 5 of the fluidized bed reduction furnace 1 by the cutting device 7a.

The iron ore is transported to the classification preheating cyclone 2 while being preheated and dried by the reducing gas exhausted from the fluidized bed reduction furnace 1.

The coarse grained iron ore is classified and collected by the classification preheating cyclone 2. The iron ore that has been classified and sized to a predetermined particle size in the classification preheating cyclone 2 is entrained by the reducing gas and transported to the solid-gas separation cyclone 3, where it is separated and collected from the reducing gas.

During the transportation, classification, and solid-gas separation process, iron ore is dried and preheated by exchanging heat with reducing gas. Solid-gas separation cyclone 3
The sized iron ore collected in the granulated iron ore flows down the transfer pipe 8 and is supplied to the fluidized bed reduction furnace 1 by the cutting device 7b.

The unreduced coarse iron ore collected by the classification preheating cyclone 2 is discharged. When supplying reduced ore and unreduced coarse iron ore to a smelting reduction furnace, the average reduction rate is adjusted to a predetermined value. Coarse-grained iron ore can be efficiently reduced by scattering from inside the smelting reduction furnace.

FIG. 2 is a configuration diagram of a fluidized bed reduction apparatus in another embodiment in which iron ore containing many fine particles, which is easily scattered during the fluidization process, is subjected to fluid reduction.

The iron ore supplied to the exhaust pipe 5 is passed to the fluidized bed reduction furnace 1 by the classification preheating bucrone 2 to remove fine iron ore that is easily scattered during the fluidization process, and the iron ore is sized to a predetermined particle size. The fine iron ore is accompanied by the reducing gas, and is separated and collected by the solid-gas separation cyclone 3.

The sized iron ore collected by the separation and preheating cyclone 2 is supplied to the fluidized bed reduction furnace 1, and the unreduced fine iron ore collected by the solid-gas separation cyclone 3 is discharged. Reduced iron ore and unreduced fine iron ore are adjusted to a predetermined average reduction rate and supplied to a smelting reduction furnace. Fine-grained iron ore can be efficiently reduced by injecting it into an iron bath or into a slab layer.

In FIGS. 1 and 2, the classified particle size is adjusted to: can. Further, the structure of the fluidized bed reduction furnace 1 is not limited to the circulation type shown in FIG. 3, but may also be of a bubbling fluidized bed, a spouted bed, or the like.

In this embodiment, the classification preheating cyclone has r and It stages, but the classification preheating cyclone can be combined into several stages to improve preheating and classification performance.

[Effect of the invention] The iron ore fluidized bed reduction apparatus of the present invention supplies iron ore raw material to the middle of the exhaust gas flue at the outlet of the fluidized bed reduction furnace, and performs preheating and drying using the sensible heat of the exhaust gas of the fluidized bed reduction furnace. Moreover, by performing classification and sieving, preheating and drying of the iron ore to be supplied to the fluidized bed reduction furnace and particle size adjustment can be carried out efficiently at the same time.

The advantages of adopting this device are listed below.

■ Coarse grained iron ore with poor fluidity and reducibility in the fluidized bed reduction furnace or fine grained iron ore that easily scatters in the furnace and has poor reduction efficiency is separated and removed, improving the reduction performance of the fluidized bed reduction furnace. do.

■It is possible to adopt a method in which particles with a poor reduction efficiency in the fluidized bed reduction furnace are removed and the removed particles are directly fed to the smelting reduction furnace. In this case, it is charged into a melting reduction furnace. reduced ore,
By ensuring the mixed reduction rate of unreduced ore to the required reduction rate, the reduction productivity of the smelting reduction equipment as a whole is improved.

■In the iron ore supply system, the sensible heat of the high-temperature exhaust gas from the fluidized bed reduction furnace is used for preheating and drying, making it possible to dry the iron ore at high temperatures, reducing the size of the drying space and increasing drying efficiency. Classification performance is improved.

■Drying and sifting is performed during the preheating process of iron ore raw materials, so the pre-drying and sifting of raw materials can be used to save equipment.

By employing the apparatus of the present invention, iron ore can be efficiently reduced.

[Brief explanation of the drawing]

1 and 2 are detailed explanatory diagrams of the present invention, and FIG. 3 is an explanatory diagram of a comparative example of a circulation type iron ore fluidized bed reduction apparatus. 1... Fluidized bed reduction furnace 2... Classification preheating cyclone 3... Solid-gas separation cyclone 4... Reducing gas supply system 5... Exhaust pipe 6... Hopper 7a
, 7b, 7c --- Cutting device 8 --- Transfer pipe
9...Reduced ore discharge system IO...Gas supply system Agent Patent attorney Tatsuo Chanoki Figure 1
Figure 2

Claims (1)

[Claims] 1. In equipment for producing reduced ore, an iron ore supply port is provided in the middle of the exhaust pipe of the fluidized bed reduction furnace, a classification preheating cyclone is provided after the iron ore supply port, and the classification preheating cyclone is An iron ore fluidized bed reduction apparatus characterized in that a solid-gas separation cyclone is provided at a subsequent stage, and the classification preheating cyclone or the solid-gas separation cyclone is connected to the fluidized bed reduction furnace through a transfer pipe. 2. The iron ore fluidized bed reduction apparatus according to claim 1, wherein a gas supply port is provided near the bottom of the classification preheating cyclone.