JPH04314806A - Device for charging raw material in smelting reduction furnace - Google Patents

Abstract

PURPOSE:To improve charging yield of char produced in a reforming process of exhaust gas from a smelting reduction furnace, into a slag layer and to improve smelting reduction reaction efficiency. CONSTITUTION:This device is the one for charging powdery ore and powdery coal into the smelting reduction furnace and has the peculiarity, in which a charging tube 1 having double structure composed of an inner cylinder 1b for flowing the powdery coal and an outer cylinder 1a for flowing the powdery ore is inserted into the smelting reduction furnace and the tip part of this charging tube 1 is positioned to above the molten slag.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for charging a raw material into a smelting reduction furnace for melting and reducing pre-reduced raw material powder ore using char obtained by reforming exhaust gas.

0002

[Prior Art] Conventionally, as equipment for such smelting reduction, there has been a fluidized bed reduction device for pre-reducing fine ore, and ore which has been pre-reduced to about 30% by this reduction device is charged from above. Iron-making equipment is known that is connected to a furnace for melting and reducing steel.

[0003] In the operation of such a smelting reduction furnace, the first
The first objective is to reduce the amount of powdered ore charged from above that is scattered by the exhaust gas blowing up from below, thereby improving the raw material yield.Secondly, the charged raw material efficiently reaches the molten slag layer in the furnace, increasing the reduction reaction efficiency. It is desirable to improve

FIG. 6 is a diagram showing the operating state of this melting reduction furnace.

As shown in the figure, fine ore and lump coal raw materials charged from the charging hole 21 of the furnace are deposited in a molten slag layer S.
By the oxygen gas 23 from the oxygen lance 22, FeO
A reaction of +C → Fe +CO occurs to form a molten iron layer M.

[0006] Carbon thus functions as an important reducing agent in the smelting reduction furnace and is consumed as the smelting reduction reaction progresses. Therefore, in order to advance the molten iron oxide reduction reaction, it is necessary to supply the pre-reduced ore and the carbon material to the melting furnace at a rate commensurate with the reaction rate, and to coexist them in the slag layer.

[0007] In this smelting reduction method, by charging the pre-reduced ore as the charging ore from above, the amount of scattering can be reduced, and the charging yield can be reduced to 95%.
% or more.

On the other hand, the charged coal is mainly used in the form of lumps with a diameter of 20 mm or more, and a small proportion of pulverized coal with a diameter of 20 mm or less is injected into the slag layer in the form of pulverized coal by a so-called injection method.

[0009] As a further development of this injection method, Japanese Patent Laid-Open No. 62-60806 discloses that CO2 and H2O in the exhaust gas of the furnace generated by powdered coal injection are reformed and reused as preliminary reducing gas. Disclosed in the official gazette. The process for this reuse is shown in FIG.

As shown in the figure, the pulverized coal 25 blown into the exhaust gas G generated in the smelting reduction furnace 24 enters the fluidized bed of the pre-reduction furnace 26 and is mixed with the pre-reduced ore 27 together with the fine ore 27.
8 is circulated to the melting reduction furnace 24, and a portion is scattered and recovered by a high-temperature solid-gas separator 29 such as a hot cyclone. This recovered pulverized coal has the properties of being crushed into fine particles during the gas reforming process, and the volatile matter is removed to form char (carbon material). It will be used as a melt reducing agent.

[0011] As described above, the pulverized coal injection method has the effect of not only simply preventing the scattering of pulverized ore, but also improving the utilization efficiency of pulverized coal in the smelting reduction method.

However, on the other hand, even if this char is injected using a blowing device, the yield of carbon material in the slag layer of the blown char is low, at 30%.
The disadvantage is that it is only a matter of degree.

[0013]

[Problems to be Solved by the Invention] The problem to be solved by the present invention is to improve the charging yield of char produced in the process of reforming the exhaust gas generated with the formation of the iron bath in the above-mentioned smelting reduction into the slag layer. The goal is to find effective means to increase the

[0014]

[Means for Solving the Problems] The present invention is characterized in that a double pipe consisting of an inner cylinder for pulverized coal inflow and an outer cylinder for fine ore inflow is provided, and the tip thereof is positioned above the slag bath in the furnace. This is a raw material charging device for a smelting and reduction furnace, in which the flow of powdered ore blown from the outer cylinder surrounds the flow of blown coal from the inner cylinder, preventing the blown coal from scattering and allowing it to flow into the slag bath. This improves the charging yield.

[0015] The ratio of the inner diameter to the outer diameter of the charging cylinder with a double pipe structure depends on the amount of fine ore and fine coal charged, but it prevents scattering (dispersion) of fine coal and improves melting and reduction. In order to effectively contribute to the reaction, it is preferably in the range of 0.5 to 0.9.

[0016]

[Function] The powdered raw coal flow, such as char, which has a low specific gravity and is easy to scatter, is charged while being wrapped in the charging powder flow, which has a large specific gravity, so scattering of the powdered coal during the charging process is prevented. . In addition, the mass effect of the charging flow increases the rate at which it reaches the iron bath slag layer.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the structure of a charging tube used in the raw material charging apparatus of the present invention, and FIG. 2 shows its cross-sectional structure. In the figure, a charging cylinder 1 has a double pipe structure with a circular cross section, consisting of an outer cylinder 1a and an inner cylinder 1b, with the outer cylinder 1a used for inflowing powdered ore, and the inner cylinder 1b used for inflowing pulverized coal. The diameter of the lower end of the charging cylinder 1 was narrowed down to a single tube structure consisting of only the outer cylinder 1a. therefore,
The lightweight powdered raw coal that easily scatters as it falls down the center of the cylinder.
The ore is charged into the slag layer S while being enveloped and covered by the falling ore powder on the outer periphery of the charging cylinder 1. In the figure, hatched areas indicate areas where fine ore flows.

FIG. 3 shows a system for charging fine ore and fine coal, and FIG. 4 shows its operating state.

In the figure, powdered ore is sent from a powdered ore hopper 2 through a cutting device 4 to a charging device 6, and powdered coal is sent from a powdered coal hopper 3 to a charging device 6 via a cutting device 5. Here, powdered ore is charged into the outer cylinder 1a of the charging cylinder 1, and powdered coal is charged into the inner cylinder 1b. Then, it falls inside the charging tube 1 and is charged into the melting reduction furnace 7 without scattering. The charged fine ore and powdered coal raw materials form a molten iron layer M in the molten slag layer S by oxygen gas 9 from the oxygen lance 8.

An example of the results of operation using the above-mentioned charging device will be shown below. Table 1 shows the chemical composition of the powdered coal used, Table 2 shows its physical properties (particle size distribution), and Table 3 shows the chemical properties of the preliminary reduction ore.
Table 4 shows the particle size distribution. The charging cylinder 1 used had a ratio of the inner cylinder diameter γ1 to the outer cylinder diameter γ2 of 0.8.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

[0024]

[Table 4]

[0025] Using the above materials, the amount of O2 charged was 18,
000Nm3/H, the amount of ore charged is 40.0t/H, and the amount of powdered coal charged is 24.3t/H, the amount of exhaust gas from the smelting reduction furnace is 64.000Nm3/H, and the amount of hot metal production is 26.0Nm3/H.
．． 4t/H (630t/D), slag production is 11.8
It was t/H.

FIG. 5 shows the yield of carbon material added to the slag layer. Here, A is when the powder is charged alone from above, and B is
C shows the case where the double tube of the above embodiment was used for charging, and C shows the case where the ore powder of the pre-reduced ore was charged.

As is clear from this example, according to the present apparatus, the yield of pulverized coal increased from 30% to 85% in the conventional method.

[0028] In addition, a powdered coal blowing device is no longer required, and productivity is greatly improved as equipment costs and maintenance costs are reduced.

[0029]

[Effects of the Invention] The following effects can be achieved by the present invention.

(1) The yield of powdered coal into the furnace is improved, and the productivity of the furnace is improved.

(2) The equipment cost for charging the raw material into the smelting reduction furnace is reduced.

(3) Equipment that was conventionally installed in the high temperature section is installed above the furnace and is simplified, reducing the frequency of failures and maintenance costs.

(4) The pulverized coal charging ratio is improved, and at the same time, pulverized coal that was conventionally discarded can now be recovered and charged, improving the raw material yield.

(5) The rate of reaching the molten slag layer is increased,
The efficiency of the melt reduction reaction is improved.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a charging cylinder used in the raw material charging device of the present invention.

FIG. 2 is a cross-sectional view of the charging tube shown in FIG. 1;

FIG. 3 is a diagram showing a system example of a charging device for fine ore and fine coal.

FIG. 4 is a diagram showing the operating state of the charging device shown in FIG. 3;

FIG. 5 is a diagram showing the yield of carbon material added to the slag layer.

FIG. 6 is a diagram showing the operating state of the melting reduction furnace.

FIG. 7 is a gas/feedstock flow system flow in a gas reformer.

[Explanation of symbols]

1 Charging tube 1a Outer cylinder 1b Inner cylinder 2　Powder hopper 3. Powdered coal hopper 4 Cutting device 5 Cutting device 6 Charging device 7 Melting reduction furnace 8 Oxygen injection lance 9 Oxygen gas S Molten slag layer M Molten iron layer

Claims (1)

[Claims] [Claim 1] A charging cylinder is provided with a double pipe structure consisting of an inner cylinder for pulverized coal inflow and an outer cylinder for fine ore inflow, and its tip is positioned above the slag bath in the furnace. Raw material charging equipment in a melting reduction furnace.