JP2679188B2 - Iron bath melt reduction ironmaking method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for improving the yield of coal charged as a fuel in the smelting reduction of iron ore.

[Conventional technology]

In iron smelting reduction using a converter-type smelting reduction furnace, as a method of charging raw materials such as iron ore and coal into the furnace, the raw material is gravity dropped from the upper part of the furnace, a so-called top-down method, and the raw material by a nozzle There is an injection method that blows into the molten metal.

Among them, the infusion method has an advantage that the raw material is directly blown into the molten metal and thus the reaction is performed with good yield, but has the following drawbacks.

The raw material needs to be crushed and the manufacturing cost is high.

Especially for carbonaceous materials, there is a danger of coal dust explosion, and explosion-proof measures are necessary. Therefore, the equipment cost is high.

The raw material supply equipment is easily worn and the equipment cost increases.

On the other hand, the superposition method does not require pretreatment of raw materials,
In terms of equipment, there is no problem like the infusion method.

[Problems to be solved by the invention]

However, in this superposition method, raw materials, particularly fine particles of coal, which is a fuel, are scattered outside the furnace together with the gas discharged from the furnace, so that there is a big problem that the yield of the carbonaceous material is very poor. According to the studies made by the present inventors, the poor yield of coal in the above-mentioned superposition method is due to thermal cracking of coal due to rapid heat rise. Coal is steam coal and has a volatile content of about 30%, but since the temperature inside the smelting reduction furnace is extremely high (1400 ° C or higher), the top-loaded coal rapidly heats up, Along with this, volatile components are rapidly gasified and thermal cracking occurs. Then, some of the fine particles generated by the thermal cracking are discharged outside the furnace together with the exhaust gas.

[Means for solving the problem]

In view of such problems, the present inventors have made repeated studies for the purpose of improving the yield of coal, and as a result, the water content in coal is higher than the conventionally considered range. It has been found that the thermal cracking can be suppressed and the coal unit consumption can be effectively reduced by adjusting the range.

Conventionally, it is generally considered that when the coal charged as carbonaceous material contains water, the latent heat of vaporization increases the basic unit of coal. Therefore, the coal is dried by sun or the like to reduce the water content to 3% or less. It was common sense to use it. On the other hand, in the present invention, the water content of coal is adjusted to a range higher than this and used.

That is, the present invention is an iron bath type smelting reduction ironing method carried out by placing a part or all of coal, which is a carbonaceous material, through a shout at the upper part of a furnace, and using coal containing 4 to 8 wt% of water as the carbonaceous material. Its feature is that it is used.

[Action]

FIG. 1 shows an example of an iron bath smelting reduction operation, in which the stirring gas from the bottom blowing tuyeres (2) and side blowing tuyeres (1) and the top blowing lance ( Oxygen is blown in from 3), and coal, which is a carbonaceous material, is charged from above the furnace together with iron ore.

Such coal scattering in the smelting reduction operation is caused by the rapid temperature rise in the high temperature furnace as described above, and the higher the heating rate, the more thermal cracking of the coal in the upper part of the furnace.

As has been conventionally considered, an increase in water content in coal increases its latent heat of vaporization, which is a factor for increasing the unit consumption of coal. On the other hand, the inventors of the present invention, latent heat of vaporization of water in coal acts to suppress thermal cracking by suppressing the temperature rise of coal, and in that respect, it becomes a factor that reduces the coal basic unit, Then, it was found that, in the range of a certain water content, the coal basic unit becomes the lowest due to the coal basic unit decreasing factor in spite of the above-mentioned coal basic unit increasing factor.

Fig. 2 shows the effect of water content in coal on the basic unit of coal. In the figure, (1) is the amount of increase in the basic unit of coal due to the latent heat of evaporation of water, and (2) is the heat generated by suppressing the temperature rise of coal. This is the amount of decrease in coal intensity due to the suppression of cracking and the decrease in coal scattering. The solid line ((1) + (2)) is the actual coal intensity obtained by offsetting the increase in (1), the decrease in (2), and the decrease in water, and the water content is in the range of 4-8 wt%. Has the lowest coal intensity. The effect is 0 water
Based on%, it will be about -40 Kg / t.

It should be noted that the coal used as the carbonaceous material usually has a particle size selected by a sieve (for example, 8 to 22 mm), but since the sieving equipment is for large-scale processing / industrial production, even if it is sieved Usually, about 10% of particles with a particle size of 8 mm or less are included. And, as in the present invention, the water content is 4 to 8 wt%
When the coal adjusted to the above is used, the fine-grained coal originally contained in the above is also charged into the furnace while still adhering to the coarse-grained surface via the adhered water, and as a result, it is scattered from the furnace mouth. Without reaching, it will reach the slag / metal layer and react. On the other hand, when using sufficiently dried coal, fine particles initially adhere to the surface of the coarse particles, but since there is almost no adhered water, the fine particles will not contact the coarse gas surface during charging. Easily separates from and scatters. As described above, according to the present invention, there is an effect that it is possible to suppress the scattering of the coal itself which is initially contained in the charged coal.

〔Example〕

Using a converter-type smelting reduction furnace (5Ton furnace) as shown in Fig. 1, smelting reduction was carried out using coal with various water contents as carbonaceous materials, and the coal scattering rate and coal basic unit were investigated. .
The results are shown in Table 1 together with the operating conditions.

[Effects of the Invention] According to the present invention described above, it is possible to suppress thermal cracking of coal placed on top and scattering of coal due to this thermal cracking, and in addition, inevitably from the beginning during charging coal. It is also possible to suppress the scattering of fine coal contained in, and by these, it is possible to effectively reduce the coal basic unit in the smelting reduction operation.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of the smelting reduction operation. Second
The figure shows the relationship between the water content of coal used in smelting reduction and the coal basic unit.

Front page continuation (72) Inventor Masahiro Kawakami Marunouchi 1-2-2, Nihon Koube Co., Ltd. (72) Inventor Kenji Takahashi Marunouchi 1-2-2 Nihon Koube Co., Ltd. (72) Inventor Masahiro Muroya 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Kokan Co., Ltd. (56) References JP 62-228413 (JP, A) JP 63-60217 (JP, A) )

Claims (1)

(57) [Claims] 1. An iron bath type smelting reduction ironing method carried out by placing a part or all of coal, which is a carbonaceous material, through a shout at the top of a furnace, and using coal containing 4 to 8 wt% of water as the carbonaceous material. Iron bath smelting reduction iron making method characterized by being used.