JPH09209018A - Method and apparatus for fluidized bed reduction of ore - Google Patents

Abstract

(57) Abstract: In a fluidized bed reduction method and apparatus for reducing ore or the like, the amount of reducing gas used is reduced, the amount of gas used is reduced, and the equipment capacity of a gas generator and a dust collector is reduced. SOLUTION: Fine powder containing C such as coke is added to ore and the like, and a gas containing oxygen is blown into the fluidized bed. The gas containing oxygen is blown in from a plurality of stages to prevent a rapid rise in fluidized bed temperature. Further, a temperature detector is provided above the nozzle for blowing the gas containing oxygen, and the oxygen flow rate is controlled so that the fluidized bed temperature does not rise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for fluidized reduction of powdery ore by using a reducing gas, in which oxygen is caused to react with fine powder containing C as a main component such as coke powder to generate heat. The present invention relates to a method and apparatus for reducing the amount of reducing gas supplied from the outside by generating the reducing gas.

[0002]

2. Description of the Related Art A method for reducing powdery ore such as iron ore by using a fluidized reduction apparatus is disclosed in Japanese Patent Laid-Open No. 61-64807 and is used for preliminary reduction of the iron ore smelting reduction method, and
A method of reducing and granulating fine ore and using it as reduced iron has been proposed. In the former case, as the reducing gas, the exhaust gas of the melting and reducing furnace heated after removing H ₂ O and CO ₂ is used, and in the latter case, the reducing gas separately prepared by the reducing gas production apparatus is used.

In the fluidized bed reduction method for powdered ores, high temperature H
_2. A high-temperature reducing gas containing CO as a main component is supplied, and the sensible heat of the reducing gas supplies the heat required for heating the ore and the reduction heat. Further, the reducing gas reduces ores and the like to generate H ₂ ,
Some of the CO changes H ₂ O, the CO _2, but reducing the powdery ore is in H ₂ O, the ratio of CO ₂ is limited. As a result, the reducing gas is supplied in an amount that satisfies both the heat supply amount and the gas composition after the reduction, and a large amount of reducing gas is required. The reducing gas is generated by partially burning a gas such as LNG, LPG, or COG, but the reducing gas temperature is
Even if oxygen is used, if the gas containing H ₂ and CO as the main components is 1
The upper limit is about 350 ° C, and for example, when reducing powdery iron ore, the temperature of the fluidized bed is set to about 900 ° C, so the effective heat utilization temperature of the reducing gas is only about 450 ° C, and the heat supply amount becomes a bottleneck. As a result, the amount of reducing gas increases, and although the gas composition has a margin, the reducing gas is supplied for heat supply.

[0004]

DISCLOSURE OF THE INVENTION As described above,
Increasing the amount of reducing gas in order to secure the amount of heat not only leads to an increase in the amount of raw material gas used to generate reducing gas and an increase in the installed capacity of the reducing gas generator, but it also increases the gas flow velocity in the fluidized bed. Since it needs to be kept constant, there are problems that the diameter of the fluidized bed increases and the capacity of the dust collector that separates gas and powdery ore becomes large.

An object of the present invention is to provide a method for significantly reducing the amount of reducing gas used in fluidized reduction of powdered ore or the like.

[0006]

The means of the present invention for solving the above problems are as follows.

(1) In a fluidized bed reduction method using a fluidized bed reduction apparatus for fluidizing and reducing powdery ore and the like using a reducing gas, flow of powdery ore and the like containing fine powder containing C as a main component such as coke A method for reducing a fluidized bed of powdered ore or the like, characterized in that a gas containing oxygen is blown into the fluidized bed of the reducing apparatus.

(2) In a fluidized bed reduction method using a fluidized bed reduction apparatus for fluidizing and reducing powdery ores and the like using a reducing gas, fluidized reduction of powdery ores containing no fine powder containing C as a main component, such as coke. A method for reducing a fluidized bed of powdered ore or the like is characterized in that oxygen is blown into the fluidized bed of the apparatus, and fine powder containing C as a main component such as coke is mixed with the powdered ore or added to the fluidized bed.

(3) In the fluidized bed reduction method according to claim 1 or 2, a plurality of oxygen blowing nozzles are provided in the height direction of the fluidized bed, and oxygen is dispersed and blown in the height direction. This is a fluidized bed reduction method for powdered ores.

(4) In a fluidized bed reducing apparatus for fluidizing and reducing powdery ore or the like using a reducing gas, a temperature detecting apparatus is provided above a plurality of oxygen blowing nozzles of the fluidized bed reducing apparatus,
A fluidized bed reduction apparatus for powdered ore or the like, characterized in that the oxygen flow rate is controlled via a temperature control apparatus.

In the present invention, when a fluidized reduction apparatus is used, powdered ore and the like contain oxygen such as coke and other fine powders containing C as the main component, and coke and the like which does not contain carbon. By adding a fine powder containing C as a main component and blowing a gas containing oxygen, it is possible to significantly reduce the amount of reducing gas used.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has the same gas discharge temperature when fine powder containing carbon as a main component and powdered iron ore, specifically, dust collected from a blast furnace is reduced using a fluidized bed. It was noted that the amount of reducing gas used increased and the ratio of H ₂ O and CO ₂ in the discharged gas decreased as compared to the case where only powdered iron ore was reduced under the conditions. In the dust collected in the blast furnace, the iron ore and a part of the coke charged in the blast furnace are accompanied by gas,
Since it is separated by a dust collector, it differs from iron ore in that it contains approximately 25% coke powder. As a result of examining this phenomenon, H ₂ O, C produced by reducing powdery ore
O ₂ undergoes the following reaction with C of coke powder to produce H ₂ and CO
It turned out to have been converted to. Furthermore, the following reaction
Since it is an endothermic reaction, it has been found that a large amount of reducing gas is necessary in order to make the gas discharge temperature the same.

C + H ₂ O = H ₂ + CO C + CO ₂ = 2CO Next, when oxygen gas was blown from the nozzle in the middle of the fluidized bed, the gas temperature at the upper part from the oxygen blowing position rose and the reduction rate of iron oxide was high. However, the gas composition remained almost unchanged. In this phenomenon, oxygen first reacts with H ₂ and CO in the reducing gas to form H ₂ O and CO ₂ , but reacts with C in the above reaction to form H ₂ and CO. This reaction is summarized by the following reaction formula. Since it is an exothermic reaction, it can be inferred that the temperature of the fluidized bed rises and the reaction rate of ore becomes faster.

C + O ₂ = 2CO As a result, when oxygen-containing gas is blown into the powdered iron ore in the state where C is present, oxygen is converted to C in the fluidized bed at high temperature.
Reacts with the gas to generate reducing gas and at the same time heats up,
It can be seen that the amount of reducing gas used can be reduced.

However, the oxygen gas blown into the fluidized bed is
There is a risk that the temperature will rise due to the reaction with H ₂ O and CO ₂ in the gas and the ore will be fused to cause blockage, but this can be prevented by dispersing and supplying a gas containing oxygen. . That is, by limiting the amount of gas containing oxygen with respect to the amount of gas and iron ore in the fluidized bed, the temperature rise can be suppressed, and the H ₂ O and CO ₂ gas produced by the reaction immediately becomes C of the coke powder. The temperature decreases due to the above reaction and the endothermic reaction due to the reduction reaction of the iron ore, and thereafter, it can be prevented by blowing the gas containing oxygen again. Further, it is preferable to control the temperature in the fluidized bed by attaching a temperature detector to the upper portion of the nozzle for blowing the gas containing oxygen and controlling the flow rate of the gas containing oxygen via the temperature control device.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a fluidized bed reduction apparatus of the present invention composed of a fluidized bed 1, a reducing gas generator 2, cyclones 3 and 4.

The reducing gas generated in the reducing gas generator 2 is supplied from the lower part of the fluidized bed 1 through the gas introduction pipe 5, and the powdered ore containing C such as coke powder supplied from the ore introduction pipe 6 is flowed. And give back. The gas obtained by reducing the ore is separated in the cyclones 3 and 4, and the ore is separated, cooled and dust-recovered. On the other hand, the ore collected in the cyclones 3 and 4 can be circulated from the powdery ore conduit 7 to the lower part of the fluidized bed 1 in order to increase the reduction rate, and the rest is discharged from the discharge conduit 8. Gas containing oxygen is introduced into the fluidized bed 1 from the oxygen introducing pipes 9A and 9B through a blowing nozzle. Temperature detecting devices 10A and 10B are provided above the blowing nozzles connected to the oxygen introducing pipes 9A and 9B, and temperature controlling devices 11A and 11B are provided.
To control the oxygen flow rate. The temperature control device is used to prevent the powdery ore from fusing due to an increase in temperature due to oxygen combustion, and the plural oxygen introducing pipes 9A and 9B are used because the temperature rises in the first stage. This is because the amount of oxygen blown in is limited because the ore melts. In this embodiment, the oxygen introduction tube 9
A and 9B are shown to be introduced from one location in the circumferential direction of the fluidized bed 1, but it is preferable to install a plurality of them in the circumferential direction to uniformly introduce oxygen. Also, the oxygen introduction tube is 9
Two locations A and 9B are shown, but it will be increased or decreased depending on the amount of oxygen introduced. On the other hand, in the case of a powdered ore containing no C, coke powder or the like is added to the powdered ore in advance, or, although not shown in this example, it is added separately from the powdered ore in the fluidized bed. Can be achieved with. The C-containing material added is preferably a low-volatile material such as coke or anthracite that does not generate a tar component in the fluidized bed.

[0018]

[Embodiments] Next, embodiments in which the blast furnace dust according to the present invention is fluidized and reduced will be described. Table 1 shows the composition of the blast furnace dust used, and Table 2 shows the composition of the reducing gas. Blast furnace dust is dried at 10.7 t / h and
Using reductive gas 15,700Nm ³ / h of 50 ° C., oxygen was reduced iron oxide and zinc oxide in the dust by blowing 800 Nm ³ / h into the fluidized bed. The fluidized bed exhaust gas temperature was 900 ° C., and the reduction rate of iron oxide was 91%, and that of zinc oxide was 89%. As a comparative example, when the blowing of oxygen was stopped, the fluidized bed exhaust gas temperature became 800 ° C., and the reduction rate of iron oxide was 62% and zinc oxide was only 58%. Next, increase the amount of reducing gas,
When the conditions for obtaining the same iron oxide reduction rate and zinc oxide removal rate were obtained, a reducing gas of 29,500 Nm ³ / h was required. Oxygen is supplied in three stages in the height direction of the fluidized bed, and four nozzles / stage are used, and the oxygen supply amount of each stage is 350, 300, and 150 Nm ³ / h from the bottom, respectively. The temperature of the upper part of the oxygen nozzle was 1000 ° C. or lower, and dust was not fused.

From the above results, by blowing oxygen into the fluidized bed, the reducing gas amount could be reduced by about 50%, and the iron oxide reduction rate could be improved by about 30% with the same reducing gas amount.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

According to the present invention, the amount of reducing gas used can be reduced by adding a gas containing oxygen to a fluidized-reduction layer such as powdered ore containing powder containing C such as coke powder. Can be reduced. As a result, the equipment capacities of the fluidized bed, the reducing gas generator and the dust collecting equipment can be made compact.

[Brief description of drawings]

FIG. 1 is a diagram showing a device configuration of the present invention.

[Explanation of symbols]

 1 fluidized bed 2 reducing gas generator 3 cyclone 4 cyclone 5 gas introduction pipe 6 powdered ore introduction pipe 7 powdered ore conduit 8 discharge conduit 9A oxygen introduction pipe 9B oxygen introduction pipe 10A temperature detection device 10B temperature detection device 11A temperature control device 11B Temperature controller

Claims (4)

[Claims] 1. A fluidized bed reduction method using a fluidized bed reduction apparatus for fluidizing and reducing powdery ore and the like using a reducing gas,
A fluidized bed reduction method for powdered ores or the like, characterized in that a gas containing oxygen is blown into the fluidized bed of a fluidized reduction device for powdered ores containing fine powder containing C as a main component such as coke. 2. A fluidized bed reduction method using a fluidized bed reduction apparatus for fluidized reduction of powdery ores and the like using a reducing gas,
Oxygen is blown into the fluidized bed of the fluidized-bed reduction apparatus for powdered ore containing C as a main component, such as coke, and fine powder containing C as a main component, such as coke, is mixed with powdered ore or added to the fluidized bed. A fluidized bed reduction method for powdered ores and the like characterized by adding. 3. The fluidized bed reducing method according to claim 1, wherein a plurality of oxygen blowing nozzles are provided in the height direction of the fluidized bed, and oxygen is dispersed and blown in the height direction. Fluidized bed reduction method for powdery ores. 4. A fluidized bed reducing apparatus for fluidizing and reducing powdery ore or the like using a reducing gas, wherein a temperature detecting apparatus is provided above a plurality of oxygen blowing nozzles of the fluidized bed reducing apparatus, and oxygen is supplied via a temperature control apparatus. A fluidized bed reduction device for powdered ores, which is characterized by controlling the flow rate.