JPS59170212A - Production of reduced iron briquette - Google Patents

Abstract

PURPOSE:To produce reduced iron briquettes without generation of combustible gas and reoxidation of reduced iron by supplying high temp. sponge-like reduced iron and fine carbonaceous material having respectively specific grain size distributions to a feeder of a compression modling device and molding the materials with forming rolls. CONSTITUTION:Reduced iron like sponge having a high temp. of >=650 deg.C and >=80% 3-30mm. and <=20% -3mm. discharged from a reduction furnace is fed via a container 1 and a storage bin 3 to a compression molding device 2 and is fed forcibly by a screw feeder 4 to forming roll 5. On the other hand, a fine carbonaceous material having 50-90% 0.075-2.0mm. grain size and <=2% moisture content is supplied via a hopper 11 of a carbonaceous material feeder 10, a constant feeder 12, a screw conveyor 13 and a chute 14 to the feeder 4. The reduced iron added with the carbonaceous material is formed by the rolls 5 to a chained reduced iron briquette of the high temp. which is then separated with a separating machine 6. The separated briquettes are dropped into a cooling water tank 8, and are transferred by a vibrating conveyor 7, from which the briquettes are conveyed by a discharging conveyor 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for producing carburized reduced iron briquettes, which are produced by compression molding high-temperature reduced iron to which fine carbon material k'11rs has been added.

Conventionally, hot or cold sponge-like reduced iron is compression molded using a compression molding machine to form briquettes to increase the size of the reduced iron and reduce the specific surface area and porosity of the reduced iron.
It is known to improve transport efficiency, provide chemical stability, and prevent re-oxidation.

For example, Figure 1 shows the high temperature (65
1 shows a known compression molding apparatus for hot reduced iron, which is used for reduced iron at a temperature of −0° C. or higher.

Sponge-like reduced iron hotly discharged from a reduction furnace (not shown) is once charged into a container 1, and then transferred to a compression molding device 2.
sent to. Note that the container 1 is of a closed type, making it possible to keep the reduced iron warm and prevent it from re-fertilizing. The container 1 is directly connected to a storage bin 3 provided on the top of the compression molding apparatus 2, and the reduced iron is charged into the storage bin 3 without being exposed to the atmosphere. Between the storage bin 3 and the forming roll 5, there is a forced feed type feeder 4, for example, a set of screws, and the reduced iron is fed to this feeder 4.
The material is forcibly fed to the forming rolls 5.

A cooling water tank 8 having a separator 6° vibrating conveyor arm is provided at the bottom of the compression molding apparatus 2.The separator 6 separates the high temperature chain-shaped reduced iron briquettes from the five forming rolls. It falls into a cooling water tank 8, is cooled in water and transferred by a vibrating conveyor 7, and is discharged from a water tank 8 furnace at a temperature above room temperature. The discharged reduced iron briquettes are transported by a transport conveyor 9 and stored, for example, in a pile.

And used as a source of molten iron in various UJ steelmaking furnaces.
In order to take advantage of this sensible heat, the product may be charged into a product container (not shown) directly below the forming rolls 5 and transported and supplied to the above-mentioned various steelmaking furnaces.

By the way, when the above-mentioned reduced iron briquettes are melted in various steelmaking furnaces to obtain molten steel of a specified steel type, if the carbon content in the above-mentioned reduced iron briquettes is insufficient, fine particles such as coke powder and carbon black may be used. An inexpensive Karo-char method in which a carbonaceous material is added to the above-mentioned reduced iron and compression molded is proposed in JP-A-53-12-712, which is capable of controlling the amount of coal. Specifically, a carbon material supply device 10 is attached to the feeder 4 of the compression molding apparatus 2 shown in FIG.

Constant feeder 12. screw conveyor 1
', is supplied through the chute 14.

However, JP-A-53-1'2'712 does not describe the particle size of the carbon material used. '-1, In the method of cold compression molding of scrap iron and steel, 7J [IL, 0.0
It is stated that coke powder of 1 fin to 2.8 m should be used.3
It remains as it is.

This defense is based on the manufacturing process of the carburized reduced iron briquettes shown in FIG. 1, especially at a high temperature of 650°C or higher.

Spongy 3~30ni 80% or more - 3cm or less 20%
When adding carbonaceous material to the above-mentioned reduced iron, it is determined whether there is a safety problem in the particle size of the carbonaceous material, moisture content, or the quality manufacturing process of carburized reduced iron briquettes II.
The present invention is based on the method of compression molding the above-mentioned high-temperature sponge-like reduced iron by adding a carbonaceous material to the method. ■The present invention provides a method for producing reduced iron briquettes that effectively prevents the generation of flammable scum due to the reaction between charcoal water and high-temperature sponge-like reduced iron, the resulting heat generation, and the formation of reduced iron. be.

The gist of the present invention is as follows.

When feeding sponge-like reduced iron to the feeder of a 6-fit type device at pressure 1, the fine carbonaceous material is fed to the feeder from the carbonaceous material feeding device C, and after the above reduced iron VC is added, this reduced iron is A method for producing reduced iron briquettes formed by a forming roll of a compression molding device is carried out at a high temperature of 650° C. or higher, into a spongy reduced iron having a particle size of 0.8 to 30 80% to 20% or less. 0 'i'
5+rtm to 2.0ttun, 50 to 90%, and a method for producing reduced iron briquettes, characterized by adding carbonaceous material having a moisture content of 2% or less.

Hereinafter, the method for producing reduced iron briquettes of the present invention will be explained.

Carbonaceous materials such as coke, carbon black, and graphite have a lower temperature than reduced iron, and when these carbonaceous materials are added to reduced iron in the form of a still-temperature sponge, during compression molding, the carbonaceous materials have a reduced iron separation effect. As a result, the density of reduced iron briquettes is lower than that of briquettes without carbonaceous additives.

The density reduction of reduced iron briquettes can be achieved by cooling the high-temperature reduced iron briquettes in water as shown in Figure 2, then taking them out into the atmosphere at room temperature or higher and cooling them in the atmosphere (the cooling process of the process in Figure 1). This is a major cause of the increase in reprinting in the industry, as well as continuous shooting during the melting process of reduced iron briquettes, and during storage (e.g., shipping by sea, storage in open air).
This causes a significant increase in reoxidation, resulting in a significant waste of reduction energy.

In addition, the decrease in strength of reduced iron briquettes may promote the generation of powder during the melting process of the briquettes in the bath melting process, causing a decrease in yield during the melting process, or may cause the generation of powder during the melting process. The increase in spread dust and the scattered dust impair the economic efficiency of the process of melting refractories, such as the sides of electric furnace lids.

Therefore, the present inventors conducted extensive research on the relationship between the particle size and particle size structure of the rejuvenating material and the density 2 strength of reduced iron briquettes.
The above-mentioned decrease in crystallinity and graininess can be minimized by investigating and reducing the grain size of carbon material by cooling it into reduced iron. 7. Heading 1 B.

In other words, carbonaceous particles with a diameter of 0.0'75 mm or less are fine, and when left in the atmosphere in the presence of moisture, they easily absorb moisture from the atmosphere and become spongy during molding. It exists between reduced irons and suppresses the mutual adhesion effect of these reduced irons. On the other hand, carbonaceous coarse particles with a diameter of 2.01 m or more are coarse, and are not placed evenly on the reduced iron during molding, and are segregated inside the reduced iron briquette, and also adhere to each other during forming. Suppresses the effect and causes a decrease in dog ellipticity 1 strength.

In this way, 0.075mm or less and 2-0 +lI#1
It is clear that the above carbon materials are not suitable for reduced iron briquettes in terms of strength and density.
75+1il11~2・O ratio of pharyngeal grain size and density and strength of reduced iron briquent, 3rd
As shown in Figure 4, C1, O, '75 +Ir
It has been found that when a carbon material of 111-2.0IIIn150-90yo is used, the density difference strength of reduced iron briquettes can be maintained even against mosquitoes. Therefore, in the present invention, the particle size structure of the carbon material is set to 0.075 to 2-0 + nm + 50
It is limited to ~90%.

As is clear from m 3v and FIG.
00'75wn~2. O+++m, 50-90%
By not using carbonaceous materials, the decrease in density can be minimized and the waste of the reduction energy can be minimized.

As is clear from FIG. 4, it is possible to minimize the decrease in strength, thereby minimizing the decrease in the conveyance yield or the economic efficiency of the melting process.

By the way, the moisture in the carbonaceous material easily reacts with the high-temperature spongy reduced iron as described below, causing the generation of hydrogen, methane, etc., and the formation of reduced iron and P+.

H20+C→CO+H2・・・・・・・(1
)2H20+2C→2CO10H4-・-(21H20
+Fe+FeO+)12...(3) Note that (11
, (in formula 21, (1)'C is the stated carbon in the warm spongy reduced iron, the free carbon, and the carbon in the carbonaceous material.

The ambient air around the compression molding equipment is the atmosphere, and water accumulation, carbon oxide, and methane generated within this equipment can be sucked into the surrounding air and cause abnormal combustion or explosions within the equipment. At the same time, the moisture content of the carbonaceous material reacts with the high-temperature sponge-like reduced iron, causing reprinting and resulting in the waste of reduced iron as mentioned above.

Therefore, the present inventors investigated the relationship between the water content in the carbon material, the oxidation property of high-temperature sponge-like reduced iron due to water content, and the gas generated during the reaction using the carburization process shown in Figure 1. However, as shown in Figure 5, the moisture content in the carbonaceous material is significantly different from the 2% condition, and it is found that reducing the moisture content in the carbonaceous material to 2Z or less is effective from the economic and safety standpoints of the carburization process. It became clear.

At Yakode Honkamei, the charcoal material moisture content is 2.7. The following is a quick guide.

Furthermore, from Figures 3 to 5, when the carbon gap 7JLl mass exceeds 3%), the density 2 strength of reduced iron briquettes, the reoxidation during compression molding, and the 16 inverse ratio, the gas generation rate tends to significantly deteriorate and increase. It is clear that the amount of carburization can be kept within 3'X. Furthermore, the results shown in Figure 3-4 are carbon material brand, coke powder, moisture content in carbon material: constant 1O%, cylinder temperature reduced iron particle size specification: '700°C.

3 to 301111n 90% 3+lock 10%, compression cylindrical shape, arrangement Is carburization conditions; Compression molding conditions constant in the process shown in FIG.

The carburizing conditions are those obtained under certain conditions. The results were also the same as those shown in Figures 3 and 4.5 for the carbonaceous materials Kekahon Blasok and graphite V'-.

Example 3 T/H (1) In view of manufacturing capacity, the compression molding apparatus shown in Fig. 1 equipped with a carbonaceous material supply device was heated at 700°C for 3 to 30 seconds.
Carbonized reduced iron briquettes (size 40CC) are produced by adding 71% carbon material to high-temperature sponge-like reduced iron of 90%, -311ag or less and 10%.
．． 0'75n~2.0? It was produced using coke powder with #172% and moisture content of 1.3%.

The results are shown in Figure 1.

Comparative Example Among the implementation conditions in the example, the particle size structure is 0.
0 'i' 5 mm ~ 2.0 +rm Results of manufacturing using coke powder with 20% and 35% moisture 0 Table 1

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of an example of compression molding equipment for reduced iron, Figs. 2 to 5 are explanatory diagrams of the method of the present invention, and Figs. Relationship diagram with “13711111 Flour Original Viability %” in the test method, 2nd
Figure 5 shows the relationship between the density of reduced iron briquettes and reoxidation.
Is the diagram moisture in the charcoal material? 1. Container 2. Compression molding device 3. Storage hinge 4. ... Feeder 5 ... Forming roll 6 ... Separator 7 ... Vibrating conhair 8 ... ... Cooling water width 9 ... ... Conveyor conveyor 10 ... Carbon material supply device 11 ... - Hopper 12 ... - Constant feeder 13 ...
・・・Screw conveyor 14 ・ ・ ・ ・
Request for chute Nippon Steel Corporation

Claims (1)

[Claims] When feeding sponge-like reduced iron to the feeder of a compression molding device, fine carbonaceous material is supplied to the feeder by the carbon material supply device and added to the reduced iron, and then this reduced iron is molded into the compression molding device. In the method for producing reduced iron briquettes formed by rolls, the cylinder temperature is 650°C or higher, and the sponge-like reduced iron of 3 to 30 mJn8o% or more - 30mJn 20% or less is mixed with grains [0, O75 + rui ~ 20jmn,
5. A method for producing reduced iron briquettes, characterized by adding charcoal paulownia with a content of 90% to 90% and a moisture content of 2'A) or less.