JPH0637660B2 - Iron ore fluidized bed reduction device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an iron ore reducing apparatus for reducing iron ore in a fluidized bed reducing furnace for use in a smelting reduction method, a blast furnace method and the like.

(Prior Art) In order to reduce iron ore to produce hot metal, a method of using a blast furnace and a method of melting iron ore reduced in a shaft furnace in an electric furnace have been conventionally adopted.

In the method using a blast furnace, a large amount of coke is used as a heat source and a reducing agent, and iron ore, which is an iron source, is usually sintered to improve the air permeability and the reducing property in the furnace, and is used as a sintered ore. It is installed in the blast furnace. From such a thing,
The blast furnace method requires coke oven equipment for dry distillation of strong coking coal and sintering equipment for producing sinter. Therefore, the blast furnace method requires a lot of energy and labor as well as a large amount of equipment cost. Therefore, the blast furnace method has a drawback that the processing cost becomes high. Furthermore, the supply of strong coking coal is unstable because the amount of endowment is small worldwide and the distribution is unevenly distributed locally.

On the other hand, the iron ore reduction method using a shaft furnace requires a pretreatment for pelletizing the iron ore, and has a drawback that it consumes a large amount of a reducing agent, expensive natural gas as a heat source, and the like.

As an alternative to such conventional hot metal production technology, the smelting reduction refining method has been drawing attention. The smelting reduction furnace used in this method was developed for the purpose of producing a molten iron-based alloy by a smaller-scale facility without being restricted by the raw material used.

As an example of the smelting reduction method described above, the present inventor has previously proposed a method constituted by the flow shown in FIG.
Proposed as No. 56.

According to this method, hot metal is manufactured as follows. That is, the iron ore 1 and the limestone 2 are heated in the fluidized bed preheating furnace 3 by the heat generated by the combustion reaction of the coal 4 and the air 5. As a result, limestone 2 (CaCO ₃ ) was converted to quick lime (Ca
O) and supplied to the fluidized bed reduction furnace 6.

In the fluidized bed reduction furnace 6, coal 7 and oxygen or an oxygen-containing gas are blown into the preheated ore and the asbestos in a fluidized state. The coal 7 exchanges heat with the preheated ore in the fluidized bed reduction furnace 6 and is thermally decomposed by partial combustion due to reaction with oxygen. Thereby, the coal 7 generates a reducing gas and
It becomes Char 9.

On the other hand, the gas generated in the smelting reduction furnace 10 or the reducing gas 11 obtained by decarbonating the gas is the fluidized bed reduction furnace 6
After being heated to 700 to 900 ° C. by heat exchange with the fuel gas 12 from the above, it is blown into the fluidized bed reduction furnace 6. The reducing gas 11 blown into the fluidized bed reducing furnace 6 is mixed with the reducing gas generated by the thermal decomposition of the coal 7, and reduces the high temperature powdery iron ore in a fluidized state to generate the reduced ore 13.

The quicklime 14 produced in the fluidized bed preheating furnace 3 is charged into the fluidized bed reduction furnace 6 together with the preheated ore to degas the gas in the fluidized bed reduction furnace 6. Then, the quicklime 14
Is discharged from the fluidized bed reduction furnace 6 together with the reduction ore 13 and the char 9.

Carbon materials such as coal and coke necessary for heat balance in the smelting reduction furnace 10 are externally added to the thus obtained reduced ore 13, char 9 and quick lime 14 and kneaded. Next, the mixture is molded into the briquette 16 by the agglomerating device 15 such as a briquette machine, and then charged into the smelting reduction furnace 10 by the charging device 17.

In the smelting reduction furnace 10, oxygen 1
9 is blown toward the bath, and bottom blown tuyere 2
Oxygen and carbonaceous materials are blown into the bath from 0. Then, the carbonaceous material contained in the briquette 16 and the bottom blown tuyere 2
Charging material that is blown with oxygen from 0, charging device 17
The carbonaceous material such as the coke 21 supplied from the above reacts with the oxygen supplied from the upper blowing lance 18, and generates a large amount of heat in the smelting reduction furnace 10. The generated heat causes the reduction ore 13 in the briquette 16 to melt, and the reduction proceeds to form hot metal.

On the other hand, the gangue in the reduced ore 13 reacts with the carbonaceous material and the quick lime 14 to generate the slag 23. The slag 23 is stored in the smelting reduction furnace 10 and its amount increases as time passes. Therefore, the slag 23 is discharged out of the furnace intermittently or continuously.

(Problems to be Solved by the Invention) In such a smelting reduction method, as is clear from the development process, the range of usable raw materials is expanded, the efficiency of heat recovery is improved, and the smelting reduction furnace is used. How to achieve the promotion of the refining reaction in the future is a future task.

However, the distribution of iron ore in the high-velocity fluidized bed used in the iron ore reduction device becomes leaner as the furnace height increases. That is, as shown in FIG. 3, the porosity indicating the concentration of iron ore decreases exponentially with the height of the furnace.

Therefore, even if the iron ore is reduced in such a state, the reactivity of the iron ore and the reducing gas is poor and the reduction rate gas utilization rate is low, resulting in a large production facility scale.

Therefore, in the present invention, by changing the shape of the fluidized bed reduction furnace itself, the internal retention amount of particles in the fluidized bed reduction furnace is increased, and the high-speed fluidization reaction is promoted by ensuring the particle concentration in the furnace height direction. .

(Means for Solving Problems) The iron ore reducing apparatus of the present invention is an apparatus for producing reduced ore used in a smelting reduction method, wherein an external particle circulation device is attached to a fluidized bed reduction furnace, A plurality of enlarging / reducing portions are provided inside the furnace in the height direction.

(Operation) The present invention is configured as described above, and a powder bed ore
A raw material such as coal is charged and reducing gas is blown from a gas blowing nozzle to fluidize raw material particles at high speed. The particles scatter with the reducing gas and flow at high speed in the fluidized bed furnace, but there are multiple enlargement / reduction sections in the height direction of the fluidized bed reduction furnace. The downflow is increased,
Particles collide with each other and particles collide with the wall, wear occurs, and the speed at which particles fly off is braked.

Further, by expanding, the emptying speed of the reducing gas decreases and the scattering speed of the particles decreases, so that the amount of particles staying in the fluidized bed reduction furnace increases, and as shown by the dotted line in FIG. Can be improved.

Further, by forming the reduced portion and the enlarged portion in the fluidized bed reduction furnace 6, the slip speed of the particles and the reducing gas becomes large, and together with the increase in the particle concentration due to the drastic improvement of the porosity in the furnace,
The fast fluidized reduction reaction can be promoted.

(Embodiment) An embodiment of the present invention will be described in detail below with reference to the schematic diagram of the basic configuration shown in FIG.

The contraction part 30 and the expansion part 31 are formed in the furnace height direction of the fluidized bed reduction furnace 6.

The embodiment of FIG. 1 has a configuration in which the middle of the fluidized bed reduction furnace 6 is enlarged, and the embodiment of FIG. 2 has a configuration in which the middle of the fluidized bed reduction furnace 6 is reduced. In this embodiment, the diameters of the reduced portions 30 or the enlarged portions 31 are made equal, but the present invention is not limited to this, and these diameters may be gradually enlarged or reduced. Also, this reduction unit 3
0, the size of the enlarged portion 31 is not particularly limited, but in the embodiment of FIG. 1, the reduced portion 30 has a diameter d, a height h, a diameter D of the enlarged portion 31, and a height H. Then, It is formed in the relationship of h = d / 2 and D = d. The expansion angle is 45 °.

In the structure of the external particle circulation device attached to the fluidized bed reduction furnace, a cyclone 32 is connected to the outlet provided at the upper portion of the fluidized bed reduction furnace 6 to capture fine particles that have been scattered along with the reducing gas 11. .

Then, below the cyclone 32, it is returned to the fluidized-bed reduction furnace 6 via a hopper 33 for temporarily accumulating the trapped particles.

On the other hand, in the furnace of the fluidized bed reduction furnace 6, a gas outlet is formed at an appropriate position and a reducing gas 11 is introduced.

When the reducing gas 11 is introduced into the fluidized bed reduction furnace 6, the iron ore contained in the reducing gas 11 is fluidized at high speed by the reducing gas. The particles scatter with the reducing gas and flow at high speed in the fluidized bed, but the fluidized bed reduction furnace 6 is provided with a contracting section 30 and an expanding section 31. The generation of eddy currents and the reduction of the emptying gas velocity improve the concentration of particles and increase the slip velocity between reducing gas and particles due to this vortex flow, the reactivity of iron ore and reducing gas is good and the reduction rate gas utilization rate is also high. Get higher

The slip velocity is the difference between the empty gas velocity and the particle rising velocity.

This equipment is not limited to the one used for the production of reduced ore for smelting reduction. For example, the reducing gas 11 may be a reducing gas such as a converter gas or a coke oven gas, or an improved reducing gas. It is also possible to reduce the iron ore with and supply it to the blast furnace for use.

(Effects of the Invention) As described above, in the present invention, since the reduced portion and the enlarged portion are formed in the fluidized bed reduction furnace, the internal circulation amount of iron ore in the fluidized bed reduction furnace is improved, Also, in combination with an increase in the slip velocity of the reducing gas 11 and particles in the furnace, it is possible to accelerate the high-speed fluidized reduction reaction, promote the efficiency of reduction, and achieve a high reaction rate and a compact gas reduction equipment by improving the gas utilization rate. It has an excellent effect such as being able to provide.

When used in the blast furnace method, it is possible to improve productivity of the blast furnace and downsize auxiliary equipment such as sintering equipment and coke oven equipment.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the basic constitution of the present invention, FIG. 2 is a front view showing another embodiment of the present invention, and FIG. 3 is a height of a fluidized bed reduction furnace and distribution of iron ore. FIG. 4 is a diagram showing the porosity, and FIG. 4 is an explanatory diagram showing the outline of the smelting reduction method previously proposed by the present inventors. 6 is a fluidized bed reduction furnace, 11 is a reducing gas, 30 is a reduction unit, 3
1 is an enlarged part, 32 is a cyclone, and 33 is a hopper.

Claims (1)

[Claims] 1. An iron ore fluidized bed reduction apparatus, characterized in that in a facility for producing reduced ore, a plurality of enlargement / reduction units are provided in a fluidized bed reduction furnace in a furnace height direction.