JPH0811804B2 - Charging method for different materials of bellless blast furnace - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for charging different raw materials into a bellless blast furnace, and more specifically, to a plurality of types having different particle sizes and / or properties. When the iron source and / or the reducing agent are divided and charged at a predetermined position in the blast furnace, the controllability of the distribution of the amount of the deposited raw material in the radial direction and / or the circumferential direction after the charging is improved. The present invention relates to a method for charging different raw materials for the purpose.

(Prior art) In the operation of a blast furnace, the weight ratio of the iron source and the reducing agent (hereinafter abbreviated as "O / C") at the top of the blast furnace, the radial distribution of the particle size, etc. are properly controlled to It is necessary to maintain the radial gas flow distribution and heat flow ratio distribution within a predetermined range to stably reduce or dissolve the ore.

In recent years, it has been aimed to improve the controllability of the gas flow distribution in the radial direction by improving the controllability of the particle size distribution in the radial direction and to lower the pig iron cost by increasing the usage ratio of inexpensive fine-grain raw materials. As a result, a so-called particle size-specific charging method has been developed in which an iron source and / or a reducing agent is classified into coarse particles and fine particles in advance, and these are separately charged into a blast furnace, and is also applied to a bellless blast furnace. Is coming.

Prior to transporting the sintered ore used as an iron source to the top of the blast furnace, Gono, etc. screened it into coarse and fine particles in the ore warehouse and divided it into coarse-grained ore and fine-grained ore. However, it has been reported about the charging method according to the particle size of the sintered ore which is charged into a predetermined position in the blast furnace ("Iron and Steel", Vol. 69, 1983, No. 4, S59).

In their grain size-specific charging method, coarse-grained sinter and pellets are mixed and used in the first charging of ore in two-part charging,
This is deposited from the middle part to the center part in the blast furnace to secure the central gas flow. On the other hand, the fine-grained sintered ore, which has a small diameter and is poor in permeability but has excellent reducibility and heat transfer properties, is divided into two parts. It is used during the second charging of the charging, and is deposited on the furnace wall of the blast furnace to appropriately suppress the furnace wall gas flow and prevent the inactivation of the lower part of the furnace.

The charging method according to the particle size of the conventional bellless blast furnace will be described with reference to FIG. The coarse-grained sintered ore 3 and the fine-grained sintered ore 3'conveyed to the furnace top of the blast furnace 1 by the belt conveyor 2 pass through the upper gate valves 4, 4'and the upper seal valves 5, 5 ', respectively, and once When the coke 7 stored in the bunker 6, 6 ′ and already charged in the blast furnace is unloaded and reaches a predetermined stock level 8, first, the furnace top bunker 6 storing the coarse-grained sintered ore 3 is first stored. The lower gate valve 9 and the lower seal valve 10 on the side are opened, and the coarse-grained sintered ore 3 is charged into the furnace through the distribution chute 11. Then, when the introduction of the coarse-grained sintered ore 3 into the furnace is completed, the lower gate valve 9 and the lower seal valve 10 are closed.

Next, the furnace top bunker 6'that stores the fine-grained sintered ore 3 '
The lower gate valve 9'and the lower seal valve 10 'on the side are opened, and the fine-grained sintered ore 3'is charged into the furnace through the distribution chute 11.

(Problems to be Solved by the Invention) However, in the conventional charging method according to particle size, there is a restriction in the charging method of the fine grain raw material, and the particle size distribution in the radial direction cannot be controlled with high accuracy. It was That is, the charging position in the radial direction of the fine-grain raw material is limited to the furnace wall. The amount of fine grain raw material used is limited. The reason is as follows, and each of them will be described in detail below.

First, the limitation of the charging position of the fine-grain raw material, which is the first problem, will be described.

In the conventional charging method according to grain size, the tilt angle of the distribution chute (θ in FIG. 6: angle formed by the bottom surface of the distribution chute and the furnace shaft of the blast furnace) is gradually decreased from a predetermined angle to feed the raw material into the furnace. It was charged from the wall toward the center of the furnace. Therefore, in most cases, the surface shape of the raw material after charging is 6th.
As shown in the figure, it has a V-shape or an M-shape, and each has a slope. Therefore, when the fine-grained sinter is charged on the coke layer, part of the surface layer of the coke layer near the charging position of the fine-grained sinter is scraped off by the impact energy possessed by the fine-grained sinter. Moving toward the center of the furnace, a mixed layer of fine-grained sintered ore and coke is formed even in the center of the furnace. In addition, the deposition angle of fine-grained sinter is smaller than that of coke, and the fine-grained sinter is loaded at a predetermined radial position in the blast furnace with high accuracy by moving on the slope of the coke layer during charging. It was difficult to enter.

Therefore, the above-mentioned Gono, etc. intended to deposit the fine-grained sinter at the charging position by using the fine-grained sinter at the second (last) time of the ore division charging instead of the first time. did. That is, coarse grained ore is used for the first time of the ore division charging, and the tilt angle schedule of the distribution chute is controlled so that the surface shape after the coarse grained ore charging is not M-shaped. That is, a recess was formed between the furnace wall and the coarse-grained sintered ore layer. Then, the schedule of the tilt angle of the distribution chute was controlled by using the fine-grained sintered ore at the second time of the divided charging of the ore, and the fine-grained sintered ore was charged into the depression.

Therefore, the mixed layer formation of the ore and the coke at the time of charging the ore is formed at the time of charging the coarse-grained sintered ore used for the first charging, and the fine-grained sintered ore is not involved. In addition, since the recesses in which the fine-grained sintered ore is charged are formed by coarse-grained sintered ore instead of coke, the layer deformation resistance when charging the fine-grained sintered ore is large, and the fine-grained sintered ore is It will be deposited at the charging position.

In this way, if the charging position of the fine-grained sintered ore is limited to the furnace wall portion, it is possible to charge the particles by sufficient grain size even with the conventional method,
Forming the aforementioned recesses at other radial positions
It is difficult due to the restriction of the charging time of coarse-grained sintered ore. That is, in the conventional charging method by particle size, since the tilt angle of the distribution chute is gradually decreased from a predetermined angle, the raw material after charging forms a slope, and in order to suppress the influence of this slope, fine particles are added. The charging position of the sinter was limited to the furnace wall.

 The second problem is the restriction on the amount of fine grain raw material used.

As described above, in the conventional charging method according to the grain size, coarse grained ore is charged on the slope of the coke layer, and fine grains are formed in the recess formed between the coarse grained ore layer and the blast furnace wall. It was charged with grain sinter. Therefore, the amount of fine-grained sinter corresponding to the volume of the depression becomes the upper limit of the amount of fine-grained sinter used, and if the amount of fine-grained sinter is increased beyond that, the amount of fine-grained sinter becomes larger. The part cannot be deposited in the recess, and it moves from the middle part of the furnace toward the center of the furnace, and it is difficult to control the deposition distribution of the fine-grained sintered ore in the radial direction with high accuracy.

It is also possible to control the schedule of the tilt angle of the distribution chute at the time of charging coarse-grained sintered ore in order to increase the volume of the depression, but this method inevitably causes O / C in the radial direction. Undesirable due to varying distribution.

As described above, in the conventional charging method according to particle size,
The tilt angle of the distribution chute is gradually reduced from a predetermined angle, and since the surface of the raw material after charging formed a slope, the charging position in the radial direction of the fine-grain raw material is limited to the furnace wall portion, and There was a limit to the amount of fine grain raw material used.

Similar problems have occurred not only in the grain size but also in the charging method of raw materials having different properties, such as when charging differently basic sinters at different positions in the furnace radial direction. .

The present invention has been made to solve the above-mentioned problems of the conventional method, and the above-mentioned problems of the conventional charging method according to particle size occur because the raw materials charged in the furnace form slopes. In view of the above, it is intended to provide a charging method according to particle size so that the deposition angle of the raw material after entering the furnace interior exceeds 0 degree and does not exceed 20 degrees.

(Means for Solving the Problems) The present invention is a method of dividing and charging a plurality of types of iron sources and / or reducing agents having different particle sizes and / or properties at predetermined positions in a furnace of a bellless blast furnace. In, the tilt angle of the distribution chute is controlled so as to charge the raw material from the center of the furnace toward the furnace wall, and the deposition angle of the raw material surface after charging is 0.
The gist is to control at least one of the tilt angle of the distribution chute, the number of revolutions at each tilt angle, and the opening of the lower gate valve so as not to exceed 20 degrees and more than 20 degrees.

The structure of the present invention will be described with reference to FIG. The coarse-grain raw material 3 and the fine-grain raw material 3'are conveyed to the furnace top by the belt conveyor 2 and once stored in the furnace-top bunker 6, 6'through the upper gate valves 4, 4'and the upper seal valves 5, 5 '. When the already charged raw material 7 is unloaded and reaches a predetermined stock level 8, first, the lower gate valve 9 on the side of the bunker 6 that stores the coarse-grained raw material 3 is stored.
And the lower seal valve 10 is opened to load the coarse grain raw material 3 into the furnace through the distribution chute 11, and when the coarse grain raw material 3 has been placed inside the furnace, the lower gate valve 9 and the lower seal valve 10 are closed. Manipulate. Next, the lower gate valve 9'and the lower seal valve 10 'on the side of the furnace top bunker 6'which stores the fine-grained raw material 3'are opened, and the fine-grained raw material 3'is introduced into the furnace through the distribution chute 11. Charge. The flow of the above raw materials is the same as the conventional method.

By the way, in the present invention, the following method is adopted in order to prevent the raw material after charging from forming a slope, which is a problem in the above-mentioned conventional charging method according to particle size.

First, the raw material is charged from the center of the furnace toward the furnace wall. For this reason, a schedule is set in which the tilt angle of the distribution chute is sequentially increased from small to large.

The arrow shown in FIG. 1 indicates the movement of the tilt angle of the distribution chute. As described above, if the tilt angle of the distribution chute is not decreased from the large size to the small size in the related art, but is gradually increased from the small size to the large size, the surface shape of the raw material after the furnace interior is easily flattened.

Secondly, since the surface shape of the raw material after charging cannot be made sufficiently flat only by changing the movement direction of the distribution chute tilt angle, the tilt angle of the distribution chute, the number of turns at each tilt angle, and the lower gate valve opening degree. Controlling at least one of the above.

In the present invention, the raw material after charging is "sufficiently flat".
Means that the moving distance of the center of gravity of the raw material after charging is within 30 cm.

The present inventors produced a full-scale model outside the furnace, changed the deposition angle of the coke layer variously, charged the fine-grained sinter on the coke layer, and The distance between the center of gravity and the charging position was measured.

The results are shown in FIG. As is clear from the figure, it was found that the distance between the center of gravity of the fine-grained ore and the charging position can be maintained within 30 cm as long as the coke layer deposition angle does not exceed 20 degrees. Therefore, if the deposition angle of the raw material after charging does not exceed 20 degrees, the surface shape of the raw material can be considered to be sufficiently flat. In order to set the deposition angle of the raw material to 0 degree, it is necessary to limit the tilt angle of the distribution chute and the number of turns in each tilt angle, and to freely control the distribution of the charge according to various purposes of the blast furnace. Is difficult. Therefore, in the present invention, a “sufficiently flat” shape is created by excluding 0 degrees (exceeding 0 degrees) and not exceeding 20 degrees.

Needless to say, the divided charging method according to the present invention can be applied not only to the particle size of the raw material but also to dividing the raw material having different properties and charging the raw material at a predetermined position in the furnace.
Here, the basicity of sinter is mentioned as an example of the property in "raw materials with different properties".

That is, in blast furnace operation, sinter ore with increased basicity is charged into the furnace wall to improve the high-temperature properties of the sinter and form a cohesive zone root stably to stabilize unloading. This is because the Si concentration in the hot metal may be reduced.

Further, in the method of the present invention, the tilt angle of the distribution chute is gradually increased, but this cannot be easily invented by any person skilled in the art.

That is, in the conventional method in which the tilt angle of the distribution chute is gradually decreased, the direction of the moment generated by the distribution chute load and the raw material load on the distribution chute and the tilt direction of the distribution chute are the same. The shaft torque applied to the motor is small, and thus is within the rated torque allowable range of the motor. On the other hand, in the method of the present invention in which the tilt angle of the distribution chute is gradually increased, the direction of the moment generated by the distribution chute load and the load of the raw material on the distribution chute is opposite to the tilt direction of the distribution chute. Therefore, the axial torque applied to the tilt motor is large,
Since it was expected that the rated torque of the motor would be exceeded, the invention such as the present invention in which the tilt angle of the distribution chute was gradually increased was not made.

However, in carrying out the present invention, the required torque of the motor shaft was actually measured when the tilt angle of the distribution chute was gradually increased, and as shown in FIG. 3, it was normally used if the conventional motor capacity was increased by about 20%. It was found that the tilt angle of the distribution chute can be gradually increased within the tilt angle range of the distribution chute.

Therefore, the present invention can be implemented in which the tilt angle of the distribution chute is gradually increased with a small investment.

(Operation) The present invention is a method of dividing and charging a plurality of types of iron sources and / or reducing agents having different particle sizes and / or properties into predetermined positions in a furnace of a bellless blast furnace, and The tilt angle of the distribution chute is controlled to charge the raw material toward the wall, and the deposition angle of the raw material surface after charging is 0.
In order to control at least one of the tilt angle of the distribution chute, the number of turns in each tilt angle, and the opening degree of the lower gate valve so as not to exceed 20 degrees and more than 20 degrees,
When a plurality of types of iron sources and / or reducing agents having different particle diameters and / or properties are divided and charged at a predetermined position in the blast furnace, the raw material in the radial direction and / or the circumferential direction of the raw material after the charging is divided. The controllability of the distribution of the deposited amount is improved.

(Actual Example) In order to confirm the effect of the present invention, a charge distribution test was conducted using a full-scale model manufactured outside the furnace. The iron source and reducing agent for each particle size used in the test are the sinter and coke for each particle size used in the actual furnace. In addition, the charging conditions of the raw materials in the test are the same as those of the actual furnace, except that there is no unloading and no blowing. Further, the deposition distribution of the fine-grain raw material in the radial direction was obtained by installing a sampling bag before charging, pulling up the sampling bag after charging the raw material, and measuring the proportion of the fine-grain raw material in the sampling bag.

The test results are shown in FIG. In the conventional charging of sinter grain size, the tilt angle of the distribution chute was set to (3344556677) for coarse-grained sinter and (1112) for fine-grained sinter. Here, the size and order of the distribution chutes are shown in parentheses, and the smaller the number, the larger the tilt angle of the distribution chutes. The number of turns is 10 for coarse-grained ore, 4 for fine-grained ore, and 14 for total ore. On the other hand, the charging of the sintered ore according to the present invention was carried out for the following two cases. Case 1 is the case where the fine-grained sinter is charged into the furnace wall as in the case of the conventional invention, and Case 2 is the case where the fine-sintered ore is charged into the middle of the furnace by taking advantage of the features of the present invention. The tilt angles of the distribution chute in Case 1 were set to (1099876543) for coarse-grained ore and (22111) for fine-grained ore. In Case 1, the amount of fine-grained ore used was increased by 25% compared to the conventional invention. In addition, the schedule of the tilt angle of the distribution chute of case 2 was set to (1099822111) for coarse-grained ore and (76543) for fine-grained ore. The amount of fine-grained sinter used is 2 compared to the conventional invention
Increased by 5%.

Although the test was not conducted on the full-scale model, there is also a method of charging the sinter in three parts as a method of charging the case 2. That is, after charging the coarse-grained sinter with (10998), the lower gate valve 9 and the lower seal valve 10 were once closed, and immediately the lower gate valve 9'and the lower seal valve 10 'were opened to fine-grained. Sinter ore was charged with (76543), and when the charging was completed, the lower gate valve 9'and the lower seal valve 10 'were closed, and immediately the lower gate valve 9 and the lower seal valve 10 were opened to obtain coarse particles. This is a method of charging sinter with (22111).

FIG. 4 shows the deposition distribution of the fine-grained sintered ore in the radial direction. In FIG. 4, a shows the charging according to the grain size by the conventional method.
Although the fine-grained sinter is charged into the furnace wall, the radial position where it is deposited is wide. On the other hand, in the case 1 in which the fine-grained sintered ore is charged into the furnace wall portion according to the present invention shown in b, the radial direction of the fine-grained sintered ore is increased even though the amount of the fine-grained sintered ore used is increased. The range of the deposition position of is smaller than that of the conventional method. That is, according to the present invention, it is possible to charge a predetermined raw material with high accuracy at a predetermined position in the blast furnace.

Further, c in FIG. 4 shows the result of the charging test according to the present invention of the fine-grained sintered ore into the middle part of the furnace, which could not be achieved by the conventional method. It was confirmed by the present invention that the fine-grain raw material can be charged into the middle part of the furnace with high accuracy.

Next, using a full-scale model, a distribution test was carried out in which 65 tons of basicity 2.0 sinter ore and 65 tons of basicity 1.8 sinter were charged from the middle part to the center part.

The test results are shown in FIG. The schedule of the tilt angle of the distribution chute according to the conventional method is (4556677) for the sinter having the basicity of 1.8, and after the sinter having the basicity of 1.8 is charged according to the above schedule, the sinter of the basicity of 2.0 is charged. Was charged on the schedule of (1112334).

Further, according to the present invention, the basicity of the furnace wall portion can be 2.0 accurately.
The following schedule for the tilt angle of the distribution chute was adopted to charge the sintered ore of First, a sinter having a basicity of 1.8 was charged into the middle part in sequence from the central part on a schedule of (10998765), and then a sinter having a basicity of 2.0 was charged to the furnace wall part on a schedule of (4322111).

Fig. 5 shows the state of radial accumulation of sinter having a basicity of 2.0. In the conventional method shown in a in the figure, the sinter having a basicity of 2.0 was divided and charged into the furnace wall. in spite of,
Deposited over a wide area in the radial direction under the influence of the sedimentary slope formed during the charging of a sinter with a basicity of 1.8.
On the other hand, in the present invention, since the sedimentary slope is not formed during the charging of the basic ore sinter of 1.8, the boundary between the basic ore 2.0 sinter and the basic 1.8 sinter is not defined. It was extremely clear, and it was confirmed that a sintered ore with a basicity of 2.0 could be charged accurately at a predetermined position in the radial direction.

(Effects of the Invention) As described above, the present invention is a method of dividing and charging a plurality of types of iron sources and / or reducing agents having different particle sizes and / or properties at predetermined positions in the furnace of a bellless blast furnace. At
The tilt angle of the distribution chute is controlled so as to charge the raw material from the center of the furnace toward the furnace wall, and the deposition angle on the surface of the raw material after the charging exceeds 0 degrees and does not exceed 20 degrees. Since at least one of the tilt angle of the distribution chute, the number of turns at each tilt angle, and the opening degree of the lower gate valve is controlled, a plurality of types of iron sources and / or reductions having different particle sizes and / or properties When the agent is divided and charged into a predetermined position in the blast furnace, the controllability of the distribution of the deposited amount of the raw material after charging in the radial direction and / or the circumferential direction is improved. Therefore, it has a great effect on the stable operation of the blast furnace.

[Brief description of drawings]

FIG. 1 is an explanatory view of the method of the present invention, FIG. 2 is a relationship diagram between a deposition angle of a coke layer and a moving distance after charging of fine-grained sintered ore, and FIG.
The figure shows the relationship between the tilt angle of the distribution chute and the motor shaft torque. Figure 4 shows the relationship between the distance from the blast furnace center and the fine-grained sinter ratio. Figure 5 shows the distance from the blast furnace center and basicity 2.0. FIG. 6 is an explanatory view of the conventional method, and FIG. 1 is a blast furnace, 3 is a coarse grain raw material, 3'is a fine grain raw material, 9 and 9'is a lower gate valve, and 11 is a distribution chute.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Yoichi Aminaga Yoichi Amanaga, No. 3, Hikari, Kashima-cho, Kashima-cho, Kashima-gun, Ibaraki Sumitomo Metal Industries, Ltd. Kashima Works (56) Reference JP-A-50-74504 (JP, A) JP-A-52-66806 (JP, A) JP-A-56-47506 (JP, A) JP-A-60-208404 (JP, A)

Claims (1)

[Claims] 1. A method of dividing and charging a plurality of types of iron sources and / or reducing agents having different particle sizes and / or properties into a predetermined position in a furnace of a bellless blast furnace, the furnace wall being located at the center of the furnace. The tilt angle of the distribution chute is controlled so as to charge the raw material toward the direction, and the deposition angle of the raw material surface after charging is 0.
Of at least one of the tilting angle of the distribution chute, the number of turns at each tilting angle, and the opening of the lower gate valve so as not to exceed 20 degrees and more than 20 degrees. Raw material charging method.