JPS6277412A - Method for blowing powder - Google Patents

Abstract

PURPOSE:To blow different kinds of powders into a blast furnace in a uniformly mixed state by passing pulverized coal and iron oxide or reduced iron through a mixer composed essentially of outer and inner pipes to mix them and by feeding the mixture to a conveying pipe. CONSTITUTION:Iron oxide or reduced iron and pulverized coal are alternately fed to intermediate tanks 3, 4, dropped into blowing tanks 5, 6, passed through conveying pipes 7, 8 and sent to a mixer 9. The iron oxide or reduced iron is introduced into the mixer 9 from the pipe 7 through the inner pipe 14 and the pulverized coal is introduced into the mixer 9 from the pipe 8 through the inflow pipe 19. In the mixer 9, mixing is carried out as if the iron oxide or reduced iron is wrapped in the pulverized coal. The mixture is fed to a conveying pipe 10 from the open end 16 of the outer pipe 15, evenly distributed with a distributor 11 and blown into a blast furnace 13 from a tuyere 12.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention transports pulverized coal and iron oxide or reduced iron cut out from a container in a solid-gas two-phase flow state, and after distribution, transports them into a blast furnace. This invention relates to a method of blowing powder into the air.

[Conventional technology]

As a conventional powder blowing method, for example, JP-A-57-
There are those described in No. 137402, JP-A-57-137403, etc. These technologies cut out pulverized coal and iron oxide or reduced iron from separate blowing tanks,
The content is to mix it in the middle of the piping and blow it into the blast furnace. At this time, the pulverized coal is supplied from the raw material hopper via the intermediate tank to the conveying pipe by the blowing tank, and is blown into the blast furnace through the blowing nozzle provided in the blowing panel. On the other hand, iron oxide or reduced iron is fed to the conveying pipe via a separate raw material hopper, an intermediate tank and a blowing tank and is likewise blown into the blast furnace via a blowing nozzle.

[Problem that the invention seeks to solve]

In such a conventional blowing method, pulverized coal and iron oxide or reduced iron are each cut out independently and mixed in the middle of a conveying pipe, so that the mixed state can be blown into the blast furnace. However, when using the conventional blowing method, there are several problems as described below.

[11i Pulverized coal and iron oxide or reduced iron are mixed in the pipe, but the mixture is not uniform.

(2) Therefore, segregation occurs at the first distributor and the first tuyere blowing section in the conveying pipe. In particular, the mixture of pulverized coal and iron oxide or reduced iron is injected with different mixing degrees at different positions around the conveyor line.

The present invention was devised in view of the problems in the prior art, and its purpose is to inject pulverized coal and iron oxide or reduced iron into a blast furnace tuyere in a uniformly mixed state. .

[Means for solving problems]

The blowing method of the present invention is to charge pulverized coal and iron oxide or reduced iron from separate raw material hoppers to a blowing tank via an intermediate tank, and to charge the pulverized coal and iron oxide or reduced iron into the blowing tank. are separately cut out from the blowing tank and sent via a conveyor pipe to a mixer installed in the vertical pipe section directly below the distributor or in the horizontal pipe section immediately adjacent to the vent section at the bottom of the pipe, and mixed in the mixer. The mixture of pulverized coal and iron oxide or reduced iron is further sent to a distributor via a conveying pipe, distributed by the distributor, and then blown into the blast furnace tuyeres.

The greatest feature of this inventive blowing method is that the pulverized coal and iron oxide or reduced iron, which have been transported separately, are uniformly mixed in a mixer, and can be injected into the lining of the blast furnace without segregation. At the point.

Hereinafter, the features of the present invention will be specifically explained using an example in which pulverized coal and iron oxide or reduced iron are transported in gas and injected into the blast furnace lining. Note that it goes without saying that the blowing method described here can also be applied to other devices that transport arbitrary particulate materials using gas.

FIG. 1 shows a system for injecting pulverized coal and iron oxide or reduced iron into a blast furnace bed.

Iron oxide or reduced iron and pulverized coal stored in raw material hoppers 1 and 2, respectively, are alternately cut into intermediate tanks 3 and 4. Thereafter, the iron oxide or reduced iron and pulverized coal that have fallen into the blowing tanks 5 and 6, respectively, are transferred to the blowing tanks 5 and 6.
and 6 and passed through conveyor pipes 7 and 8 to mixer 9
The material is transported by airflow using a separate transport system until the end of the process. mixer 9
The iron oxide or reduced iron and pulverized coal that have flowed into the pipe are uniformly mixed there and flow into the distribution device 11 through the conveying pipe 10 again. The solid-gas two-phase flow that has flowed into the distributor W11 is evenly distributed to a plurality of discharge ports, airflow-transported to the blast furnace tuyeres 12, and blown into the blast furnace 13.

FIG. 2 illustrates the internal structure of the mixer 9, which is the most important part of this transport system. The main part of the mixer is formed by an inner tube 14 and an outer tube 15. The outer tube 15 is open at one end 16 and is connected to the conveying pipe 1.
Connected to 0. The other end 17 is closed. An inflow opening 1 is located closer to the closed end 17 than the center of the outer tube 15.
8, to which an inflow pipe 19 is connected. This inflow pipe 19 is connected to the conveyance pipe 8 at the other end. Furthermore,
The closed end 17 of the outer tube 15 has an inlet opening 20;
An inner pipe 14 is connected thereto. One end 21 of this inner tube 14 is connected to the conveying tube 7.

In the mixer 9 having such a structure, iron oxide or reduced iron flows through the inner pipe 14, and pulverized coal flows through the inlet pipe 19. As a result, the pulverized coal wraps around the iron oxide or reduced iron, and the mixture is mixed into the outer tube.
5 into the conveying pipe IO through the open end 16 of the pipe.

〔Example〕

Next, the effects of the present invention will be specifically explained with reference to Examples.

In this example, pulverized coal and pellet feed were mixed and blown using the blowing device shown in FIG. Then, the degree of mixing at the one tuyere blowing section after the distributor was investigated by measuring the total steel percentage.

That is, pellet feed and pulverized coal, whose total steel frame percentage is known in advance, are each cut out from the blowing tank 22 at a constant cutting speed, flowed into the mixer 24 via the conveying pipe 23, and distributed by the distribution device 25, and then A collector 26 collects the data. After cutting out the powder for a certain period of time, the cutting is stopped, the collected powder is reduced by the collector 26, and a certain amount of sample is taken out. The total percent iron content of the powder mixture taken out was measured using a high frequency inductively coupled plasma emission spectrometer. At this time, the theoretical mixing degree is defined by the following equation.

Blow tanks 22 and 27 each have a diameter of 7.00 mm.
A main body consisting of a cylindrical upper part and a conical lower part with a height of 3800 m and a charging tube of mm 28.29 and a diameter of 1300 Il111 and a diameter of 105.311 Il! l carrying pipe 23.3
0. The mixer 24 is connected to the inner pipe 3 of the inflow pipe 31.
2 and an outflow tube 33 with a diameter of 105.3+ nm. Moreover, the distribution device 25 has a diameter of 472 mm and a height of 1350 mm.
mm, and the number of distribution is 16.

Pellet feed and pulverized coal are each cut out from the blowing tank 22, 27 at a constant speed, and are fed into the conveying pipe 22.
．． 30 and enters the mixer 24. At this time, the pulverized coal flows into the mixer 24 from the inlet pipe 31 and the pellet feed flows from the inner pipe 32. The inflowing pellet feed is mixed with pulverized coal in a state where it is surrounded by pulverized coal,
It flows out into the conveying pipe 34 via the outflow pipe 33. and,
After being distributed by the distribution device 25, it is collected by the collector 26. The collected powder was sampled at four sampling positions around the circumference at 90 degree intervals. Sampling was performed by collecting the collected mixture using the reduction method.

In Figure 4, the radial axis represents the total iron deviation (%);
The circumferential direction shows 16 distribution positions, A and B.

The deviation (%) of the total iron content at each position of C and D is indicated by an X mark.

The total iron content deviation (%) in this case is defined by the following formula.

As is clear from Figure 4, pulverized coal and pellet feed are distributed and blown in a uniformly mixed state without segregation.
The total iron content deviation (%) remains at a maximum of about ±3%.

〔Effect of the invention〕

Conventionally, desiliconization of hot metal has been carried out between blast furnace converters in steel works by methods such as desiliconization in a blast furnace cast bed, desiliconization by injection in a pig iron car, and the like.

On the other hand, the removal of S from the blast furnace tuyere explained in the embodiment of the present invention
The i-method is a Si-removal method that has been attracting attention in recent years due to its prevention of hot metal temperature drop and cost reduction.

By employing the present invention in such a Si removal method, pulverized coal and iron oxide or reduced iron can be mixed uniformly. In addition, since the mixture of pulverized coal and iron oxide or reduced iron flows into the distribution device in a uniformly mixed state, it is evenly distributed in the many tuyere injection parts, and is fed into the blast furnace at the same mixing degree. It becomes possible to inject. Therefore, it becomes possible to operate the blast furnace under stable conditions, and it is possible to promote an excellent Si removal reaction.

[Brief explanation of drawings]

Fig. 1 schematically shows the blowing method according to the present invention, Fig. 2 shows the structure of a mixer used in the method, and Fig. 3 is a schematic diagram of the experimental equipment for the blowing method of the present invention. , FIG. 4 is a diagram showing the deviation relationship of the total iron content % between the tuyeres according to the device. 1.2: Raw material hopper 3, 4: Intermediate tank 5.6.
22, 27: Blowing tank? ,8,10.23i3
0.34: Conveying pipe 9.24: Mixer 11.25: Distribution device

Claims (1)

[Scope of Claims] 1. A combination of pulverized coal and iron oxide or reduced iron that is blown into a blast furnace from a blast tuyere together with pulverized coal to reduce the Si content in the pig iron being tapped. In the powder injection method, pulverized coal and iron oxide or reduced iron are installed in a piping line, one end of which is open and connected to the conveyance outflow piping, and the other end is connected to a closed outer pipe. , formed by an inner tube whose one end fits into an inflow opening provided at the closed proximal end of the outer tube and whose other end is connected to a conveying inflow tube, and an inflow opening at the middle of the outer tube. A powder blowing method characterized by mixing the powder in a mixer having a structure in which an inflow pipe is connected and blowing the powder into a blast furnace.