JPH01263206A - Method for charging raw material into blast furnace - Google Patents

Abstract

PURPOSE:To reduce the cost of manufacture of pig iron by dividing plural kinds of raw materials having different compsns. and grain sizes into plural units and by charging a mixture of fine sintered ore having a specified grain size with other raw materials every time when specified units are charged. CONSTITUTION:Plural kinds of raw materials having different compsns. and diameters, e.g., coke, sintered ore, raw ore and pellets are divided into plural units and these units are successively charged into a blast furnace. At this time, a mixture of fine sintered ore having 2-10mm diameter with raw ore and pellets is charged every time 2-10 units are charged. The cost of manufacture of pig iron can be reduced.

Description

[Detailed Description of the Invention] [Industrial Field of Application] Regarding the method of charging raw materials in a blast furnace, more specifically, it concerns the method of charging raw materials in a blast furnace. 4 is divided into multiple batches and charged into the blast furnace as one unit, so-called particle size separation, I.
This relates to a PI charging method.

[Conventional technology]

In recent years, from the perspective of lowering pig iron costs, there has been an increase in the use of fine-grained raw materials in blast furnaces, but this is simply a matter of reducing the lower limit of particle size by reducing the mesh of the raw #4 sieve in front of the furnace. In this case, the gas ventilation resistance within the furnace increases, which may lead to unstable blast furnace operation.

Therefore, when increasing the amount of fine-grained raw materials used, the particle size distribution in the blast furnace radial direction is controlled more than ever before, thereby maintaining the radial gas flow distribution in an appropriate shape and increasing the flow rate inside the blast furnace. It became necessary to suppress the increase in ventilation resistance. As one method, the ``granularity separate *'l 'A person method'' has been proposed.

In this method, for example, as shown in Japanese Patent Application Laid-Open No. 55-28308, the charging raw material is divided into a plurality of particle size ranges having a predetermined particle size and charged into a furnace. The conventional dividing charging method according to particle size will be explained based on FIG.

The raw material to be charged into the blast furnace consists of a plurality of units (m units), of which m-1 units are in charging mode A and the remaining one unit is in charging mode B. However, one cycle of charging is represented by (m-1)A4-B.

In charging mode A, the raw materials of coke, raw ore, pellets, and normal sintered ore are divided into four parts and charged into the blast furnace without containing fine sintered ore. Charging mode B is a mode that includes fine-grained sintered ore, and by charging only the fine-grained sintered ore at once in the final charging divided into four parts, the fine-grained and coarse-grained 1;9
This suppresses the decrease in porosity due to porosity.

[Problem to be solved by the invention]

However, such a conventional charging method according to particle size has the following unresolved problems.

That is, in the conventional method, in order to suppress the non-uniform distribution of fine particles in the circumferential direction of the blast furnace, the last two
If the charging amount of fine sintered ore is equal to the total charging amount of raw ore, pellets and normal sintered ore in the last charging of charging mode B, fine sintered ore is A phenomenon occurs in which the blast furnace layer covers the entire top of the blast furnace layer. As a result, the gas inevitably encounters a layer of fine particles, so an increase in ventilation resistance is unavoidable.

In addition, when the amount of fine grain sintered ore put into the blast furnace is reduced in the final charging divided into four parts in charging mode B, the distribution of fine grains in the blast furnace [J direction AJ direction is uneven]. There are concerns that this will happen. Non-uniform distribution of fine particles, even if only to a small extent, can cause ill! The large air abrasion resistance causes a deviation in the gas flow distribution in the circumferential direction, making blast furnace operation unstable.

The object of the present invention is to provide a method for dividing charging according to particle size, which solves these problems.

[Means to solve the problem]

The raw material charging method in a blast furnace according to the present invention includes coke,
Are the compositions and particle sizes of sintered ore, raw ore, pellets, etc. different? When dividing several kinds of raw materials into multiple parts and charging them into the blast furnace as one unit, the charging is divided into multiple parts at a rate of once for every 2 to 10 units charged. In one charging, fine sintered ore having a grain size of 2 to 10 mm is mixed with raw ore and pellets and then charged.

[For production]

In order to solve the problems with the conventional split charging method according to particle size, the present invention firstly charges fine sintered ore instead of charging fine sintered ore separately. A method was adopted in which coke was mixed with pellets and raw ore, which were slightly larger in particle size than coke but smaller in particle size than coke. Second and first, the charging mode in the raw material charging method of the present invention is shown.

The raw material to be charged into the blast furnace consists of a plurality of units (m unit), of which the m-14 peak is charging mode A, which is the same as the conventional method. However, in charging in charging mode B, fine sintered ore is charged together with raw ore and pellets, which is different from the conventional method.

According to this, it is possible to make the amount of charging each time almost equal in the last two charging times in charging mode B,
Non-uniform distribution of fine particles in the circumferential direction of the blast furnace can be suppressed. In other words, when fine-grained sintered ore is charged together with raw ore and pellets, classification occurs on the slope of the blast furnace layer m due to differences in particle size. Unevenly distributed in limited areas near walls. As a result, the gas can pass through avoiding the fine grain portions, and the increase in ventilation resistance will not be noticeable.

When charging the fine sintered ore together with the raw ore and pellets, the appropriate weight ratio was, for example, 2+1.9 L and 5, respectively.

In Fig. 2, charging modes A and B consist of four charging times, but the number of charging times in each mode is not particularly limited.
Further, the charging order is not particularly limited, and the order of fine sintered ore in charging mode B is not limited to the final number. The number of times of charging, the raw materials to be charged, and the order of charging in the charging modes 1'A and 1'H are appropriately determined based on the unloading conditions of the blast furnace such as slip and blow-through.

Secondly, in the present invention, the particle size of the fine sintered ore used is 2 to 1.
It is characterized by being limited to a range of 0 inches.

FIG. 3 shows the pressure 1i4 when fine-grained sintered ore is charged with different particle sizes using a small-sized blast furnace model, which is converted into an actual blast furnace.

As shown in M, the horizontal axis shows the minimum grain size (-
1), and the vertical axis shows the force loss (in the packed bed of the blast furnace) 1;
kg/c+J), it can be seen that at the lower limit particle size of 31 or less, the pressure tN loss increases rapidly, and at 2 or less, slagging occurs and operation becomes impossible.

Therefore, the lower limit particle size of fine particles that can be used in a blast furnace is 2-
It is. In addition, the particle size range of sintered ore with normal particle size is 10
~151M, so the limit grain size of fine sintered ore is 1 oin. From the above, in the present invention, the particle size range of the fine sintered ore is limited to 2u to 1Qmm.

Thirdly, the present invention is characterized in that the value of m is limited to 2 to 10 in charging the blast furnace raw material in which m units are one cycle. FIG. 4 shows the relationship between the value of m and the rate of increase in pressure loss when fine-grained sintered ore is charged using a small blast furnace model.

As shown in the figure, the charging interval of fine sintered ore is plotted on the horizontal axis.
Furthermore, if we take the rate of increase in pressure loss on the vertical axis, the charging interval of fine sintered ore that minimizes the rate of increase in pressure loss in the furnace depends on the consumption amount of fine sintered ore in the blast furnace. It can be seen that the charging interval increases as the consumption of fine sintered ore decreases. 1ffi
Usually, the amount of fine sintered ore used in a blast furnace is I 000t/d.
Since a y ~50 t/d a y, it is desirable to limit m, that is, the charging interval of fine sintered ore, to a value of 2 to 10 in order to minimize the increase in pressure tjl loss.

Figure 5 shows that the consumption of fine sintered ore in the blast furnace is 200L/
The radial deposition distribution of fine sintered ore in the case of d a y is shown. In the case of fine-grained sintered ore charging interval m-2, Fig.
), the fine-grained sintered ore enters into the voids of the coarse-grained raw material, so the porosity decreases, and as a result, the rate of increase in pressure ti loss becomes significant. On the other hand, the charging interval of fine-grained sintered ore is large, m = 12
In this case, as shown in FIG. 5(C), the fine sintered ore covers the entire surface layer of the blast furnace, resulting in a large upper U ratio of pressure loss.

When m=5, as shown in FIG. 5(b), the rate of increase in pressure becomes the minimum because fine sintered ore is unevenly distributed near the furnace wall.

Fine-grained sintered ore exhibits the above-mentioned deposition behavior, so the normal use range of fine-grained sintered ore is 100OL/day to 50t/day.
For y, it is desirable to limit the charging interval m of fine sintered ore to a value of 2 to 10.

〔Example〕

A test was conducted to confirm the effects of the present invention on a blast furnace with an internal volume of 5000 r&.

The fine sintered ore used had a particle size of 5 to 8 yen, and the consumption amount in the blast furnace was 400 t/day. On the other hand, the particle size of coke, raw ore, normal sintered ore, beret/ ) is 25
~50 fins, 15-30 cranes, 10 ~15 hawks, and 8-16 intestines. Coke in charging mode A, raw ore,
The charging amounts of sintered ore and pellets are 32t and 18t, respectively.
85L, lot. In addition, charging mode B was completely defeated by charging mode A in terms of the amount of coke, raw ore, and pellets charged.

The charging amount of fine sintered ore in the last charging of charging mode B was +6 t, and the value of m was set to 4.

After operating for about a month under the above charging conditions, the pressure was tM.
The increase in losses is 15%, which is almost the same as the predicted value from model experiments.
Therefore, the operation could be carried out in an extremely efficient manner.

〔Effect of the invention〕

As is clear from the above explanation, the raw material charging method of the present invention is able to suppress the non-uniformity of fine grains in the circumferential direction in the blast furnace, despite using sintered ore with a small particle size. Therefore, it is possible to suppress the gas permeation resistance to a small value, eliminate the bias in the gas flow distribution in the circumferential direction, and stabilize the blast furnace operation. Therefore, according to the raw material charging method of the present invention, inexpensive fine-grained raw materials can be used in the blast furnace without any problems, and the effect of this in reducing ironmaking costs is great for JG.

[Brief explanation of the drawing]

Figures 1 and 2 are schematic diagrams showing the conventional method and the raw material charging method of the present invention, respectively, Figure 3 is a chart showing the relationship between the particle size of fine sintered ore and pressure IN loss in the blast furnace, and Figure 4 5 is a graph showing the relationship between the charging interval of fine-grained sintered ore and the rate of increase in pressure loss in the blast furnace, and FIG. 5 is a partial cross-sectional view showing the radial deposition distribution of fine-grained sintered ore. Charging mode A Charging mode B Charging mode B Figure 3 Lower limit grain size of fine sintered ore (mm) Figure 4 Charging interval of fine sintered ore (m)

Claims (1)

[Claims] 1. When dividing multiple types of raw materials with different compositions and particle sizes such as coke, sintered ore, raw ore, and pellets into multiple units and charging them into the blast furnace as one unit, 2 to 10 units of Fine-grained sintered ore with a grain size of 2 to 10 mm is mixed with raw ore and pellets and charged in one charging divided into multiple parts. Features of raw material charging method in blast furnace.