JP6907988B2 - Raw material transfer method and equipment in blast furnace - Google Patents

Description

The present invention relates to a method and equipment for transporting blast furnace raw materials stored in a raw material tank for each type to a blast furnace.

In the raw material transfer equipment of the blast furnace, iron raw materials such as sinter, lump ore, and pellets, and slag-making materials as auxiliary raw materials are separately stored in a plurality of raw material tanks. In addition, the sinter may be stored in different raw material tanks depending on the particle size, such as coarse particles and fine particles. When sending these plurality of types of raw materials to the blast furnace, as shown in FIG. 7, the raw materials discharged from each raw material tank 10 are conveyed to the surge hopper 12 (relay tank) by the belt conveyor 11, and a plurality of types of raw materials are sent. After the raw materials are collectively stored in the surge hopper 12, they are discharged from the surge hopper 12 and transported to the top hopper 14 of the blast furnace by a belt conveyor 13 or the like. In such a raw material transport facility, by storing the raw material in the surge hopper 12, for example, even if a problem occurs in the raw material dispensing mechanism of the raw material tank 10, the raw material stored in the surge hopper 12 is stored in the blast furnace while performing the restoration work. It is possible to reduce the risk that raw materials cannot be transported to the blast furnace.

The hopper, which is usually installed in a raw material transport facility, is characterized in that the raw material in the hopper is discharged first, and the raw material directly above the hopper outlet is discharged first from the lower side to the upper side, and then laterally from directly above the hopper outlet. It is known to exhibit a so-called funnel flow in which raw materials located at distant places are discharged. In this case, the order of the raw materials put into the hopper and the order of the raw materials discharged from the hopper are different. That is, when the raw materials are charged into the hopper, the raw materials charged first are deposited on the bottom layer, and thereafter, the raw materials are laminated upward according to the charging order, and the raw materials charged last are laminated on the uppermost layer. .. On the other hand, when the hopper is discharged, the portion directly above the hopper outlet is discharged first as described above.

Therefore, in the raw material transport facility as shown in FIG. 7, when sintered ore, lump ore, pellets, slag-making material, etc. are stored in each of the plurality of raw material tanks 10, different raw materials are stored from the plurality of raw material tanks 10. Even if they are discharged in order, when these raw materials are charged into the surge hopper 12 and discharged from the surge hopper 12, they are not sent to the furnace top hopper 14 in the order in which they are discharged from the raw material tank 10. Therefore, even if the delivery order from the raw material tank 10 is manipulated in an attempt to intentionally control the order of charging different kinds of raw materials into the furnace top hopper 14, there is a problem that the different raw materials are not charged into the furnace top hopper 14 in that order.

On the other hand, as shown in FIG. 8, if the equipment configuration is such that the raw materials are directly transported from the raw material tank 10 to the furnace top hopper 14 without providing the surge hopper, the raw materials discharged from the plurality of raw material tanks 10 are in that order. Is sent to the furnace top hopper 14. Such a raw material transfer facility has an advantage that it is easy to control the order of charging different kinds of raw materials to the furnace top hopper 14. However, if a problem occurs in the feeding mechanism of the raw material tank 10, there is a problem that the raw material cannot be sent to the blast furnace because the surge hopper does not have a buffer function.

Miwa, "General Theory of Powder Engineering", Nikkan Kogyo Shimbun, 1981, p.125 Okuno et al., "Improvement of all-coke operation by sinter particle size-based charging method", Iron and Steel, The Iron and Steel Institute of Japan, 1983, 69, 14, p.1578-1584 Yamada et al., "Distribution of Charges and Breathability of Large Blast Furnace", Kawasaki Steel Technical Report, Kawasaki Steel Co., Ltd., 1974, vol.6, No.1, p.16-37

As described above, when the raw material is sent from the raw material tank to the blast furnace top hopper via the surge hopper, there is a problem that the raw material cannot be sent to the blast furnace top hopper in the order in which the raw material is discharged from the raw material tank. In addition, when the raw material is sent from the raw material tank to the furnace top hopper of the blast furnace without relaying the surge hopper, if the buffer for storing the raw material is exhausted and a problem occurs in the dispensing mechanism of the raw material tank, the raw material is sent to the blast furnace. There is a problem that it becomes impossible to send.

Therefore, an object of the present invention is to dispense raw materials from the raw material tank when transporting the blast furnace raw materials stored in the raw material tank by type to the blast furnace in an equipment configuration provided with a hopper for temporarily storing the raw materials discharged from the raw material tank. The purpose of the present invention is to provide a method and equipment for transporting raw materials that can be sent to the blast furnace in the same order.

The gist of the present invention for solving the above problems is as follows.
[1] A plurality of raw material tanks (1) for storing blast furnace raw materials by type, and a hopper (2) for temporarily storing the raw materials discharged from the plurality of raw material tanks (1) before being transported to the furnace top hopper of the blast furnace. ) Is used to transport raw materials to the blast furnace and charge them into the furnace.
A method for transporting raw materials in a blast furnace, characterized in that the flow of raw materials when discharged from the hopper (2) is mass flow.
[2] In the blast furnace according to the raw material transport method of the above [1], the cone portion inclination angle α (however, the inclination angle of the hopper cone portion from the horizontal plane) of the hopper (2) is α> 62 °. Raw material transportation method.

[3] In the raw material transport method of the above [1] or [2], in order to supply the raw material to one furnace top hopper by relaying the hopper (2), the sintered ore and the lump are sent from different raw material tanks (1). A method for transporting raw materials in a blast furnace, which comprises paying out lump ore prior to sinter when paying out ore.
[4] A plurality of raw material tanks (1) for storing blast furnace raw materials by type, and a hopper (2) for temporarily storing the raw materials discharged from the plurality of raw material tanks (1) before being transported to the furnace top hopper of the blast furnace. ) In the raw material transfer equipment of the blast furnace
A raw material transfer facility in a blast furnace, wherein the hopper (2) has a structure in which the flow of raw materials at the time of being discharged is mass flow.
[5] In the raw material transfer equipment of the above [4], in a blast furnace characterized in that the cone portion inclination angle α (however, the inclination angle of the hopper cone portion from the horizontal plane) of the hopper (2) is α> 62 °. Raw material transfer equipment.

According to the present invention, in the equipment configuration provided with a hopper for temporarily storing the raw materials discharged from the raw material tank, the raw materials were discharged from the raw material tank when the blast furnace raw materials stored in each type in the raw material tank were transported to the blast furnace. It can be sent to the blast furnace in order. For this reason, it becomes easy to control the distribution of charged materials in the blast furnace, and it is possible to suppress the pulverization of raw materials (particularly sinter) by selecting the order of raw material discharge from the raw material tank, which is stable. Blast furnace operation can be performed.

The drawing which shows the blast furnace raw material transfer layout in one Embodiment of this invention method An embodiment of the surge hopper (hopper 2) of FIG. 1 is schematically shown. FIG. 1A is a plan view, and FIG. 1B is a vertical sectional view. The surge hopper used in the examples of the present invention of the examples is schematically shown. FIG. (A) is a plan view, and FIG. (B) is a vertical sectional view. The surge hopper used in the comparative example of the example is schematically shown. FIG. (A) is a plan view, and FIG. (B) is a vertical sectional view. Explanatory drawing which shows raw material delivery condition from raw material tank in Example Explanatory drawing which shows the sampling method of the blast furnace input raw material in an Example Drawing showing blast furnace raw material transfer layout with surge hopper Drawing showing blast furnace raw material transfer layout without surge hopper

The raw material transfer method in the blast furnace of the present invention includes a plurality of raw material tanks 1 for storing blast furnace raw materials by type, and a hopper 2 (generally, a hopper 2) for temporarily storing the raw materials discharged from the plurality of raw material tanks 1 before being transported to the blast furnace. When the raw material is transported to the blast furnace and charged into the furnace by the raw material transport facility equipped with (called a surge hopper), the flow of the raw material when it is discharged from the hopper 2 is mass flow.
Here, the mass flow means that when the raw material is dispensed from the lower part of the hopper, the descending speed of the raw material in the lateral direction in the hopper is almost uniform and there is almost no velocity distribution, and the raw material is dispensed in order from the raw material located on the lower side. It refers to the phenomenon in which the raw material located at the top is discharged at the end. Here, if the descent speed in the horizontal cross section of the hopper deviates within ± 10%, it is considered that it can be practically treated as a mass flow.

FIG. 1 shows a blast furnace raw material transfer layout according to an embodiment of the present invention, in which raw materials discharged from a plurality of raw material tanks 1 are transported to a hopper 2 (surge hopper) by a belt conveyor 3 and a plurality of types are shown. After the raw materials of the above are collectively stored in the hopper 2, they are discharged from the hopper 2 and transported to the top hopper 4 of the blast furnace by a belt conveyor 5. However, in the present invention, the discharge of the raw materials from the hopper 2 is mass-flowed. Is to be.
When the raw materials discharged from the plurality of raw material tanks 1 are charged into the hopper 2, the raw materials charged first are deposited in the lowest layer, and then they are laminated upward according to the charging order, and finally. The input raw material is laminated on the uppermost layer. Therefore, if the raw material discharge from the hopper 2 is made into a mass flow, this order is maintained even when each raw material is charged into the hopper 2 and discharged from the hopper 2 in the order in which the raw materials are discharged from the plurality of raw material tanks 1. As a result, the raw materials are sent to the blast furnace (furnace top hopper 4) in the order in which they were discharged from the raw material tank 1. Therefore, it becomes easy to control the order of charging different kinds of raw materials to the top hopper 4 of the blast furnace. Further, due to the existence of the hopper 2 (surge hopper), even if a problem occurs in the raw material dispensing mechanism of the raw material tank 1, the raw material stored in the hopper 2 can be sent to the blast furnace while performing the restoration work. It is possible to reduce the risk of being unable to supply raw materials to.

Non-Patent Document 1 shows the following equation (1) as a condition that the flow of powder in the hopper is mass flow.
Cone tilt angle α> 45 ° + φr / 2… (1)
Here, α is the inclination angle of the cone portion from the horizontal plane, and φr is the angle of repose of the powder.
Further, Non-Patent Document 2 indicates that the angle of repose of a sintered ore having a particle size range of 5 to 18 mm used in a blast furnace is 34 °, and raw materials are discharged (dispensed) from the hopper 2 from these. ) Is used as the mass flow, and the cone portion inclination angle α> 62 ° of the hopper 2 is derived. Here, the angle of repose of the cone portion is set based on the angle of repose of the sinter. Generally, the sinter accounts for 70% or more of the blast furnace iron raw material, and this characteristic causes the flow of the blast furnace iron raw material in the hopper. This is because it has a great influence on sex.
That is, in order to make the raw material discharge (payout) from the hopper 2 a mass flow, it is preferable that the cone portion inclination angle α (however, the inclination angle of the hopper cone portion from the horizontal plane) is α> 62 °. On the other hand, if the inclination angle of the cone portion becomes excessive, it is necessary to increase the height of the hopper when trying to secure the same volume, which increases the construction cost. From this point of view, it is considered that the upper limit of the cone inclination angle α is about 70 °.
FIG. 2 schematically shows an embodiment of a hopper 2 having such a cone portion inclination angle α, FIG. 2A is a plan view, and FIG. 2B is a vertical sectional view.

If the order in which dissimilar raw materials are charged into the top hopper 4 of the blast furnace can be controlled, for example, a charging method capable of reducing pulverization in the raw material transport process as shown below becomes possible.
Non-Patent Document 3 shows the particle size of the raw material after being discharged from the ore storage tank (raw material tank) and the particle size of the raw material in the blast furnace. In the case of ore, the particle size is lower in the blast furnace than after the mine tank was discharged. This is because the particles are broken by the drop impact when they are put into the surge hopper and when they are put into the furnace top hopper after being cut out from the storage tank, and the particle size is reduced. This phenomenon is particularly remarkable in the sintered ore. Is. It is desirable to suppress the decrease in the particle size of the raw material because it becomes a factor that hinders stable operation by increasing the ventilation resistance in the blast furnace. In order to suppress this particle size reduction phenomenon, the drop impact at the time of charging the hopper may be reduced, and as a means thereof, a raw material having a small particle size reduction due to the drop impact such as lump ore is charged into the hopper in advance. If the sinter is put on top, (i) the height of the fall in the hopper will be reduced, and (ii) the cushioning effect of the lump ore deposited earlier will be obtained, resulting in a decrease in particle size due to the drop impact. Can be expected to be suppressed.

Therefore, in the method of the present invention, when the raw material is supplied to one furnace top hopper 4 via the hopper 2, if the lump ore is discharged from the raw material tank 1 prior to the sinter, the hopper 2 (surge hopper) Not only that, since the lump ore and the sintered ore are charged into the furnace top hopper 4 in this order, in each hopper, the sintered ore is charged onto the lump ore that was first charged into the hopper and deposited at the bottom of the hopper. This means that (i) the drop height when the hopper is put in is reduced, and (ii) the cushioning effect of the lump ore deposited earlier is obtained, so that pulverization due to the drop impact is suppressed. If a conventional funnel flow type surge hopper is used to dispense from such a raw material tank, the sintered ore is charged onto the lump ore when the surge hopper is charged, but when it is discharged from the surge hopper. By mixing the lump ore and the sinter, a part of the sinter is put into the furnace top hopper in advance along with the lump ore, which has the effect of reducing the drop impact of the sinter. It becomes smaller.

In the raw material transfer facility of the blast furnace having the surge hopper shown in FIG. 3 and the conventional surge hopper shown in FIG. 4, the raw materials are discharged from the raw material tank in the order of lump ore and sinter, and baked when they are put into the blast furnace. The powder ratio of the ore was investigated. 3 and 4 schematically show the configuration of the surge hopper, respectively, where FIG. 3A is a plan view and FIG. 4B is a vertical sectional view. Here, the cone portion inclination angle α of the surge hopper of FIG. 3 is 65 °, and the cone portion inclination angle α of the surge hopper of FIG. 4 is 60 °. By experiments using a surge hopper model with a scale of 1/10, it was confirmed that the type shown in FIG. 3 has mass flow characteristics and the type shown in FIG. 4 has funnel flow flow characteristics. Therefore, the case where the surge hopper shown in FIG. 3 is used is an example of the present invention, and the case where the surge hopper shown in FIG. 4 is used is a comparative example.

In the raw material transport facility having each type of surge hopper, as shown in FIG. 5, after dispensing the lump ore 6a corresponding to 30% by mass of the total raw material from the raw material tank 1a, 70% by mass of the total raw material is discharged from the raw material tank 1b. Sintered ore 6b corresponding to the above was dispensed. After these raw materials are put into the furnace top bunker via the surge hopper, when they are charged into the blast furnace, a part of the raw materials is sampled by the sampling device 7 at the position shown in FIG. The -5 mm ratio was investigated. The raw material was discharged from the furnace top hopper over 90 seconds, and during this period, a total of 200 kg of raw material was collected every 10 seconds by a sampling device. This was separated into samples of 1 to 5 mm and 5 mm or more by a sieve, and the sinter in the sample was visually separated from the lump ore to calculate the -5 mm ratio in the total sinter. Here, the drop strength defined by JIS M8711 was 96 for lump ore and 89 for sinter.

The ratio of -5 mm in the sinter was 25% by mass in the comparative example, 20% by mass in the example of the present invention, which was 5% by mass lower than that in the comparative example. This is because, in the comparative example, a part of the lump ore and the sinter are mixed when they are discharged from the surge hopper and the furnace top hopper, so that the effect of reducing the drop impact cannot be sufficiently obtained. In the example of the present invention, since the lump ore and the sinter are discharged from the surge hopper and the furnace top hopper in the order in which they are discharged from the raw material tank, the lump ore resistant to a drop impact precedes the surge hopper and the furnace top hopper. It is probable that due to the addition, the decrease in the particle size of the sinter due to the drop impact at the time of introduction into the hopper could be suppressed.
In addition to the above-mentioned lump ore, as the raw material to be discharged from the raw material tank prior to the sinter in order to suppress the pulverization of the sinter due to the drop impact, for example, pellets, slag-making materials and the like are used as sub-materials. One or more of raw materials, carbon-containing raw materials such as small lump coke and ferro coke, non-calcined lump ore using cement as a binder, metallic raw materials such as scrap, etc., which have higher drop strength than sintered ore. May be good.

1,1a, 1b Raw material tank 2 Hopper 3 Belt conveyor 4 Furnace top hopper 5 Belt conveyor 6a Mass ore 6b Sintered ore 7 Sampling equipment

Claims (2)

A plurality of raw material tanks (1) for storing raw materials for blast furnaces by type, and a hopper for temporarily storing raw materials discharged from the plurality of raw material tanks (1) before being transported to the top hopper of the blast furnace. A surge hopper (2) having a single raw material dispensing port only at the lowermost end of the section, and a belt conveyor (5) that transports the raw material discharged from the surge hopper (2) to the furnace top and puts it into the furnace top hopper. When transporting raw materials to the blast furnace and charging them into the blast furnace,
The cone portion inclination angle α (however, the inclination angle of the hopper cone portion from the horizontal plane) of the surge hopper (2) is α> 62 °, and the flow of the raw material when it is discharged from the surge hopper (2) is mass flow. A method for transporting raw materials in a blast furnace. When sinter and lump ore are discharged from different raw material tanks (1) in order to supply raw materials to one furnace top hopper via the surge hopper (2), the sinter ore precedes the sinter. The method for transporting raw materials in a blast furnace according to claim 1, wherein the raw material is discharged.

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