JPWO2020166347A1 - Raw material charging method and blast furnace operation method for bellless blast furnace - Google Patents

Abstract

Provided are a method for charging a raw material of a bellless blast furnace capable of charging a raw material at a predetermined position in a furnace without impairing productivity, and a method for operating a blast furnace using the method for charging the raw material.
This is a method of charging raw materials for a bellless blast furnace in which the distribution chute is swiveled to charge iron source raw materials and carbonaceous materials into the blast furnace. It has a repulsive plate, and the turning speed of the distribution chute is faster than 10 rpm.

Description

The present invention relates to a raw material charging method for a bellless blast furnace for the purpose of reducing the reducing agent ratio of the blast furnace and a blast furnace operating method using the raw material charging method.

In blast furnace operation, in general, coke and iron source raw materials are alternately charged as charges from the upper part of the blast furnace. Coke is used as a reducing agent and fuel. The iron source raw material is an iron-containing oxide such as sinter, pellets, and lump ore. In the following description, these iron source raw materials are collectively referred to as "ore". In the blast furnace, coke layers and ore layers are alternately formed to form a raw material deposition layer. Hot air is blown from the tuyere at the bottom of the blast furnace, and at the same time, auxiliary fuel such as pulverized coal and tar is blown into it.

In order to maintain stable operation of the blast furnace, it is necessary to ensure good air permeability of the raw material sedimentary layer against the gas flowing from the lower part of the furnace to the upper part of the furnace and to stabilize the gas flow in the furnace. Stabilization of the gas flow in the furnace is achieved by ensuring a stable central gas flow and furnace wall gas flow. The air permeability of the raw material sedimentary layer is greatly affected mainly by the properties, particle size and charge of coke and ore. Further, it is greatly influenced by the method of charging the charged material from the top of the furnace, that is, the distribution state of the charged material charged in the furnace. In the following description, this charge distribution status will be referred to as "charge distribution".

Conventionally, control of the mass ratio distribution of the coke layer and the ore layer in the radial direction of the blast furnace has been most often used for controlling the distribution of the charged material. In the following description, the mass ratio of the coke layer and the ore layer is described as "[Ore / Cake]". Blast furnaces are classified into bellless blast furnaces and bell blast furnaces according to the type of raw material charging equipment. In either case of the bellless blast furnace or the bell blast furnace, it is effective to reduce the value of [Ore / Cake] in the center of the furnace in order to obtain a particularly stable gas flow.

In recent years, operations with a high pig iron ratio, a high pulverized coal ratio, and a low fuel ratio have been carried out. In such an operation, the operating conditions are such that the amount of ore is large relative to the amount of coke charged. In the following description, such operating conditions will be referred to as "high O / C conditions". In the blast furnace operation under the “high O / C condition”, the ratio of the ore layer having a large aeration resistance in the raw material sedimentary layer becomes high, so that the pressure loss at the upper part of the furnace increases. As a result, a stairwell is generated, and the contents are not stably lowered, and shelving or slipping are likely to occur. Due to such a phenomenon, the stable operation of the blast furnace is greatly hindered, and the productivity is significantly reduced. Therefore, in order to realize stable operation under high O / C conditions, it is necessary to control (Ore / Cake) more precisely.

In Patent Document 1, when the distance from the furnace center in the furnace radius direction is r (m) and the furnace inner radius at the furnace mouth is Rt (m), the furnace inner region in the furnace radial direction is defined as the furnace center. From the side, r / Rt ≦ 0.20: 1st region, 0.20 <r / Rt ≦ 0.80: 2nd region, 0.80 <r / Rt: 3rd region, and [Lo / (Lc + Lo) )] (However, a method of controlling Lo: ore layer thickness, Lc: coke layer thickness) so as to have a charging distribution satisfying the following conditions (a) to (d) is disclosed.
(A) Mean value of the first region: less than 0.5 (b) Mean value of the second region: 0.6 or more and less than 0.9 (c) Mean value of the third region: 0.4 or more and less than 0.8 (D) Mean value of the first region <Mean value of the third region <Mean value of the second region In this method, while ensuring the air permeability in the blast furnace in the first and third regions, the [2 region [ By increasing Lo / (Lc + Lo)], the reduction efficiency of the entire blast furnace is increased.

By the way, as a means for charging raw materials from the top of the furnace, a bellless charging device provided with a distribution chute is widely used. Since this bellless charging device can adjust the drop position and the accumulated amount of the raw material in the radial direction of the furnace by changing the tilt angle and the number of turns of the distribution chute, [Ore / Cake] can be controlled by this. The tilt angle of the distribution chute is an angle formed by the vertical direction and the angle at which the raw material flows on the chute surface of the distribution chute.

In order to deposit the raw material at a predetermined position in the furnace, it is effective to reduce the deposition width of the raw material charged in the furnace. Patent Document 2 discloses a method of reducing the deposit width of the deposit by setting the linear velocity V at the tip of the distribution chute to a predetermined value or less determined from the properties of the raw material to be charged.

JP-A-2018-193579 Japanese Unexamined Patent Publication No. 2003-328018

In recent operations under high O / C conditions, it is not sufficient to simply reduce [Ore / Cake] in the central portion to form an inverted V-shaped fusion zone shape to stabilize ventilation. It is necessary to reduce [Ore / Cake] in the furnace wall to ensure ventilation, and to increase [Ore / Cake] in the middle to improve the reduction efficiency of the entire furnace. For this purpose, it is necessary to stably and surely deposit the raw material from the top of the furnace at a predetermined position in the furnace via the distribution chute.

In order to deposit the raw material at a predetermined position in the furnace, it is necessary not only to reduce the deposition width of the raw material as disclosed in Patent Document 2, but also to suppress the collapse of the raw material deposited at the predetermined position. Therefore, it is necessary to optimize the turning speed of the distribution chute at the time of charging the raw material while reducing the deposit width and suppressing the collapse of the raw material deposited at the predetermined position.

The reduction in the tip speed of the distribution chute disclosed in Patent Document 2 leads to an extension of the charging time, which may hinder productivity. The present invention solves the above-mentioned problems, and provides a raw material charging method for a bellless blast furnace capable of charging raw materials at a predetermined position in a furnace without impairing productivity, and a blast furnace operating method using the raw material charging method. The purpose is to provide.

The features of the present invention for solving such a problem are as follows.
[1] A method of charging raw materials for a bellless blast furnace in which an iron source raw material and a charcoal material are charged into a blast furnace by turning a distribution chute. A method for charging raw materials for a bellless blast furnace, which has a repulsion plate that inclines downward from the transport direction and has a turning speed of the distribution chute faster than 10.0 rpm.
[2] The method for charging raw materials for a bellless blast furnace according to [1], wherein the turning speed of the distribution chute is 12.0 rpm or more.
[3] The tilt angle of the distribution chute is set with respect to the distance d from the turning center of the distribution chute to the raw material deposition level in the furnace at the start of charging the raw material, the furnace mouth radius Ro, and the angle α determined by the following equation (1). The method for charging raw materials for a bellless blast furnace according to [2], which comprises 1.36α or more.
tanα = Ro / d ... (1)
[4] The method for charging raw materials for a bellless blast furnace according to [1], wherein the turning speed of the distribution chute is 14.0 rpm or more.
[5] The tilt angle of the distribution chute is set with respect to the distance d from the turning center of the distribution chute to the raw material deposition level in the furnace at the start of charging the raw material, the furnace mouth radius Ro, and the angle α determined by the following equation (1). The method for charging raw materials for a bellless blast furnace according to [4], which comprises 1.41α or more.
tanα = Ro / d ... (1)
[6] A blast furnace operating method in which an iron source raw material and a charcoal material are charged into the blast furnace by the method for charging a raw material for a bellless blast furnace according to any one of [1] to [5].

In the method for charging raw materials for a bellless blast furnace according to the present invention, the turning speed of the distribution chute is made faster than 10.0 rpm to charge the ore and the carbonaceous material into the blast furnace. As a result, the deposition angle of the carbonaceous material around the furnace wall can be increased and the deposition width can be reduced without impairing the productivity. As a result, the area of the region where [Ore / Cake] is reduced can be reduced in the furnace wall portion, so that the gas utilization rate of the blast furnace is improved and the operation with a low reducing agent ratio and a low coke ratio is realized.

FIG. 1 is a schematic view showing an outline of the model equipment 10. FIG. 2 is a perspective view and a cross-sectional view showing the tip end portion of the distribution chute 18 including the repulsion plate 22. FIG. 3 is a graph showing the weight distribution obtained by the charging experiment. FIG. 4 is a schematic cross-sectional view of the model equipment 30 used in the coke deposition angle measurement experiment. FIG. 5 is a schematic view showing the state in the furnace when the charging of the raw material is started.

In order to confirm the falling behavior of coke from the distribution chute in a bellless blast furnace, the present inventors used a 1 / 17.8 scale model facility 10 of a blast furnace ^{having an internal volume of 5,005 m 3 and a furnace diameter of 11.2 m.} A coke charging experiment was conducted. FIG. 1 is a schematic view showing an outline of the model equipment 10.

The model equipment 10 includes a furnace top bunker 12, a collecting hopper 16, a distribution chute 18, and a sampling box 24. The furnace top bunker 12 has three hoppers 14 for accommodating coke and ore. At the bottom of each hopper 14, a gate is provided to allow the discharge of the contained raw material. The collecting hopper 16 supplies the raw material discharged from the furnace top bunker 12 to the distribution chute 18. The distribution chute 18 has a chute 20 and a repulsion plate 22. The sampling boxes 24 are provided in four directions radially around a position corresponding to the turning center of the distribution chute 18. Each sampling box 24 has a plurality of accommodating portions 26 divided at intervals of 20 mm from the center side to the outside.

The height at which the sampling box 24 was installed was set so that the opening at the top of the sampling box 24 was at a level of 424 mm vertically downward from the center position of tilting / turning of the distribution chute 18. Since the furnace diameter of the model equipment 10 is 630 mm, this level difference corresponds to 0.67 times the furnace diameter.

FIG. 2 is a perspective view and a cross-sectional view showing the tip end portion of the distribution chute 18 including the repulsion plate 22. FIG. 2A is a perspective view, and FIG. 2B is a cross-sectional view. Assuming that the transport direction of the distribution chute 18 is the direction of the arrow 21 in FIG. 2B, the repulsion plate 22 is provided at the tip of the distribution chute 18 so as to be inclined downward from the transport direction.

The repulsion plate 22 is provided so that the horizontal distance (L in FIG. 2B) from the tip of the chute 20 to the repulsion plate 22 is 70 mm when the transport direction of the chute 20 is parallel to the horizontal. ing. The inclination angle of the repulsion plate 22 (θ in FIG. 2B) is 23 ° with respect to the horizontal direction. When changing the angle of the repulsion plate 22, the length of the repulsion plate 22 was adjusted so as not to change the horizontal distance from the chute 20 to the repulsion plate 22.

The coke charging experiment using the model equipment 10 was carried out according to the following procedure. First, 3 kg of coke having a particle size of 2.0 mm to 2.8 mm was charged into the furnace top bunker 12. The gate opening of the furnace top bunker 12 was adjusted so that 3 kg of coke could be cut out in 17 seconds. Next, the gate was opened, the coke was cut out from the furnace top bunker 12 into the collecting hopper 16, and the coke was dropped through the distribution chute 18. The coke that fell from the distribution chute 18 was accommodated in the accommodating portion 26 of the sampling box 24. Coke is an example of carbonaceous material.

The weight of the coke contained in each accommodating portion 26 of the sampling box 24 was measured, and the weight distribution of the dropped coke in the radial direction was calculated. FIG. 3 is a graph showing the weight distribution obtained by the charging experiment. The horizontal axis of FIG. 3 is the position (mm) in the radial direction from the center, and the vertical axis is the cumulative weight frequency (%). Cumulative weight frequency is defined as the ratio of the weight of coke that reaches the center side from that position to the total weight of coke at a position separated from the center by a predetermined distance.

In the charging experiment, the position where the cumulative weight frequency was 50% was defined as the mainstream drop position, and the radial interval when the cumulative weight frequency was 5% to 95% was defined as the drop width. The tilt angle of the distribution chute 18 was adjusted so that the position of the furnace wall vertically 424 mm vertically below the center of tilting / turning coincided with the cumulative weight frequency of 95%, that is, 315 mm from the center of the furnace.

The charging experiment was conducted by setting the shoot 20 length of the distribution chute 18 to 240 mm and changing the turning speed of the distribution chute 18 to 42.2, 50.6, and 59.1 rpm. Since the model equipment 10 is 1 / 17.8 scale of the actual blast furnace, considering that the Froude number is constant as a condition that the trajectory of the raw material falling from the distribution chute 18 is similar to that of the actual machine, the turning speed 42 in the model equipment 10 .2 rpm corresponds to the turning speed of 10.0 rpm of the actual blast furnace. The turning speed of 50.6 rpm in the model equipment 10 corresponds to the turning speed of 12.0 rpm of the actual blast furnace. The turning speed of 59.1 rpm in the model equipment 10 corresponds to the turning speed of 14.0 rpm of the actual blast furnace. This charging experiment was carried out with and without the repulsion plate 22 attached. The experimental conditions and results are shown in Table 1 below.

表１に示すように、先端に反発板２２を装着した分配シュート１８を用いた場合、旋回速度の上昇に伴ってコークスの落下幅が小さくなった。一方、先端に反発板２２を装着していない分配シュートを用いた場合、旋回速度の上昇に伴ってコークスの落下幅は大きくなった。この結果から、先端に反発板２２を装着した分配シュート１８を用い、分配シュート１８の旋回速度を４２．２ｒｐｍより速くしてコークスを装入することで、コークスの落下幅を小さくできることが確認された。

As shown in Table 1, when the distribution chute 18 having the repulsion plate 22 attached to the tip was used, the falling width of the coke became smaller as the turning speed increased. On the other hand, when a distribution chute without the repulsion plate 22 attached to the tip was used, the fall width of the coke increased as the turning speed increased. From this result, it was confirmed that the falling width of the coke can be reduced by using the distribution chute 18 having the repulsion plate 22 attached to the tip and charging the coke with the turning speed of the distribution chute 18 faster than 42.2 rpm. It was.

Next, a coke deposition angle measurement experiment will be described. FIG. 4 is a schematic cross-sectional view of the model equipment 30 used in the coke deposition angle measurement experiment. The model equipment 30 includes a furnace top bunker 12, a collecting hopper 16, a distribution chute 18, and a model furnace 32 having a furnace diameter of 630 mm. The furnace top bunker 12, the collective hopper 16, and the distribution chute 18 are the same as those used in the model equipment 10. In the deposition angle measurement experiment, first, a deposit surface having an inclination angle of 16 ° was prepared in the model furnace 32. Then, in the same procedure as the charging experiment, coke was dropped onto the deposition surface via the distribution chute 18, and the deposition angle of the coke deposited near the furnace wall was measured. The tilt angle of the distribution chute 18 was adjusted within a range in which the mainstream drop position 424 mm vertically below the center of tilt / turning was 285 to 325 mm from the center of the furnace. The mainstream drop position was measured by conducting a coke charging experiment using the model equipment 10. The results are shown in Tables 2 and 3 below.

表２に示すように、先端に反発板２２を装着した分配シュート１８を用いた場合、旋回速度が同一の条件では、コークスの堆積角が極大となる傾動角度が存在した。主流落下位置が壁面から中心側に離れている場合は、壁面に衝突するコークスの粒子数が少ないため堆積角が小さくなる。主流の落下位置が壁面に近い場合においても、壁面に衝突するコークスの粒子数が多く、壁面からの反発が大きくなってコークスの堆積角が小さくなる。このように、主流落下位置が壁面から離れていても堆積角が小さくなり、主流落下位置が壁面に近づいてもコークスの堆積角が小さくなるので、この間にコークスの堆積角が極大となる傾斜角が存在する。

As shown in Table 2, when the distribution chute 18 having the repulsion plate 22 attached to the tip was used, there was a tilt angle at which the coke deposition angle was maximized under the same turning speed conditions. When the mainstream drop position is far from the wall surface toward the center, the deposition angle becomes small because the number of coke particles colliding with the wall surface is small. Even when the mainstream drop position is close to the wall surface, the number of coke particles colliding with the wall surface is large, the repulsion from the wall surface is large, and the coke deposition angle is small. In this way, the deposition angle is small even if the mainstream fall position is far from the wall surface, and the coke deposition angle is small even if the mainstream fall position is close to the wall surface. Exists.

When the turning speed of the distribution chute 18 became high, the mainstream drop position at the tilt angle at which the deposition angle became maximum changed to the furnace wall side. When the turning speed is increased, a centrifugal force acts on the coke flowing through the distribution chute 18 as compared with the case where the turning speed is low, so that the coke falls farther. As described above, even if the mainstream fall position is the same, the fall width is smaller when the turning speed is higher than when the turning speed is lower, so that the fall width collides with the furnace wall before reaching the sedimentary surface. The number of coke particles is reduced. Therefore, the mainstream drop position at the tilt angle at which the coke deposition angle is maximized changes to the furnace wall side when the turning speed is high than when the turning speed is low.

When the turning speed becomes high, the coke deposition angle increases even when the mainstream drop position is on the furnace center side. This is because the speed of the coke particles in the horizontal direction is also increased by increasing the swirling speed, and even if the mainstream drop position is on the center side of the furnace, the coke particles that collide with the deposition surface move to the side of the furnace wall. It is considered that this increased the coke deposition angle. Comparing the maximum values of the coke deposition angle under the same turning speed for each turning speed, the maximum value of the deposition angle increased as the turning speed increased.

On the other hand, as shown in Table 3, when a distribution chute without the repulsion plate 22 attached to the tip was used, the maximum value of the deposition angle under the same turning speed condition became smaller as the turning speed increased. .. It is considered that this is because the fall width in the radial direction became large due to the increase in the turning speed and the coke was sparsely deposited.

As described above, it was confirmed that when the distribution chute 18 having the repulsion plate 22 attached to the tip thereof is used, the coke deposition angle can be increased by increasing the turning speed of the distribution chute 18. From this result, it is possible to increase the deposition angle of coke near the furnace wall by using the distribution chute 18 with the repulsion plate 22 attached to the tip and charging the coke with the turning speed of the distribution chute 18 faster than 42.2 rpm. Was confirmed.

The reason why the coke deposition angle near the furnace wall increased is that the swirling speed of the distribution chute 18 increased, which reduced the fall width of coke in the radial direction and coke densely deposited in a specific region in the radial direction. In addition, as the falling speed of coke in the turning direction increased, the direction in which the accumulated coke collapsed changed from the furnace center direction to the turning direction as compared with the case where the turning speed was low, and as a result, the coke accumulated. It is thought that this is because the coke is less likely to collapse.

Next, for the purpose of confirming the influence of the shoot length of the distribution chute 18, the same charging experiment was performed by changing the shoot length of the distribution chute 18. The results are shown in Table 4 below. The tilt angle was set under the condition that the coke deposition angle was maximized within the range where the mainstream drop position 424 mm vertically below the center of swivel and tilt was 285 to 325 mm from the center of the furnace.

表４に示すように、分配シュートのシュート長を２４０ｍｍから２２０ｍｍに短縮すると、表１に示したシュート長が２４０ｍｍ分配シュートを用いた場合よりもコークスの落下幅が大きくなり、コークスの堆積角は小さくなった。しかしながら、シュート長が２２０ｍｍの分配シュートを用いた場合であっても、分配シュートの旋回速度を５０．６ｒｐｍ以上にすることで、旋回速度を４２．２ｒｐｍとした場合よりもコークスの落下幅は小さくなり、炉壁近傍のコークス堆積角は大きくなった。

As shown in Table 4, when the shoot length of the distribution chute is shortened from 240 mm to 220 mm, the shoot length shown in Table 1 becomes larger than that when the 240 mm distribution chute is used, and the coke deposition angle becomes larger. It became smaller. However, even when a distribution chute with a chute length of 220 mm is used, by setting the swirl speed of the distribution chute to 50.6 rpm or more, the falling width of coke is smaller than when the swivel speed is 42.2 rpm. As a result, the coke deposition angle near the furnace wall increased.

When the shoot length of the distribution chute was extended from 240 mm to 260 mm, the coke drop width was smaller and the coke deposition angle was smaller than when the distribution chute with a chute length of 240 mm was used. Even when a distribution chute with a chute length of 260 mm is used, by setting the swirl speed of the distribution chute to 50.6 rpm or more, the fall width of coke becomes smaller than when the swivel speed is 42.2 rpm, and the furnace wall. The coke deposition angle in the vicinity increased. From this result, the fall width of coke and the deposition angle of coke are slightly affected by the change in the shoot length of the distribution chute, but the fall width of coke is reduced by making the turning speed faster than 42.2 rpm. It was confirmed that the tendency to increase the coke deposition angle does not change.

The raw material charging method for the bellless blast furnace according to the present invention is based on the results of the above-mentioned coke charging experiment. The swirling speeds of the distribution chute 18 in the model equipment 10 and the model equipment 30 are 42.2 rpm, 50.6 rpm, and 59.1 rpm, which correspond to the swirling speeds of the distribution chute in the actual blast furnace of 10.0 rpm, 12.0 rpm, and 14.0 rpm. Therefore, in the raw material charging method of the bellless blast furnace according to the present embodiment, a distribution chute having a repulsion plate inclined downward from the transport direction of the distribution chute is used at the tip, and the turning speed of the distribution chute is made faster than 10.0 rpm. The ore and carbonaceous materials are charged into the blast furnace. As a result, the deposition angle of the carbonaceous material charged into the furnace wall of the blast furnace can be increased and the fall width can be reduced without impairing the productivity. As a result, the area of the area where [Ore / Cake] is reduced can be reduced in the furnace wall of the blast furnace, which improves the gas utilization rate of the blast furnace and realizes low coke ratio operation with low reducing agent ratio in the blast furnace. it can.

The turning speed of the distribution chute is preferably 12.0 rpm or more. As a result, the coke deposition angle of the furnace wall portion can be made larger than when the turning speed is less than 12.0 rpm, and as shown in Examples described later, the reducing agent ratio and the coke ratio in the blast furnace operation can be further reduced.

It is more preferable that the turning speed of the distribution chute is 14.0 rpm or more. As a result, the coke deposition angle of the furnace wall portion can be made larger than when the turning speed is less than 14.0 rpm, and the reducing agent ratio and the coke ratio in the blast furnace operation can be further reduced.

Furthermore, if the distance from the center position of the tilting / turning of the distribution chute to the raw material deposition level in the furnace at the start of raw material charging is shortened, the distance from the chute tip to the deposit surface is reduced, and the coke drop width is further reduced. Become. However, in order for the mainstream drop position to reach the furnace wall, it is necessary to increase the tilt angle. When the tilt angle is increased, when the deposit surface of the raw material is lowered, the fall width of the mainstream drop position toward the furnace wall becomes large. Therefore, it can be said that in the operation of the blast furnace, it is easily affected when the raw material deposition level in the furnace at the start of raw material charging fluctuates. From this point of view, it is preferable that the distance from the center position of the tilting / turning of the distribution chute to the raw material deposition level in the furnace at the start of charging the raw material is 0.60 times or more the radius of the furnace opening. Here, the raw material deposition level in the furnace at the start of charging the raw material is the level of the deposited surface of the raw material in the furnace at the time when the charging of the raw material is started from the distribution chute.

FIG. 5 is a schematic view showing the state in the furnace when the charging of the raw material is started. With reference to FIG. 5, the deposition surface level of the raw material in the furnace at the start of charging the raw material will be described.

Although the deposition surface of raw materials is not horizontal in the blast furnace, in blast furnace operation, detection means such as sounding to detect the deposition surface level of raw materials near the furnace wall is used to determine the timing of starting the charging of raw materials. ing. This detection means detects that the deposited surface level has dropped to a certain level, and starts charging a predetermined amount of raw material at the detected timing. As a result, the sedimentary surface level in the furnace is controlled to be within a predetermined range. Therefore, in the present embodiment, the deposited surface level of the raw material in the furnace at the start of charging the raw material is defined as the horizontal plane 40 at the deposited surface level of the raw material near the furnace wall detected by the detection means. Further, in the embodiment described below, the tilt angle of the distribution chute 18 is set to the distance d between the center position 42 of the tilt / turn of the distribution chute and the horizontal plane 40 which is the deposition surface level of the raw material in the furnace at the start of charging the raw material. It is expressed using the furnace mouth radius Ro and the angle α determined by the following equation (1). The tilt angle of the distribution chute in this embodiment is the angle formed by the distribution chute 18 in the direction of transporting the raw material and in the vertically downward direction.
tanα = Ro / d ... (1)

Next, an embodiment will be described. A blast furnace having an internal volume of 5,005 ^{m 3} and a furnace diameter of 11.2 m was used. The ore was cut out from the mine tank and stored in the top hopper, and the coke was cut out from the skeleton tank and stored in another top hopper. Then, the ore and coke were alternately cut into a distribution chute having a repulsion plate, and the ore and coke were deposited in the blast furnace, and the blast furnace was operated.

In Comparative Example 1, the shoot length of the distribution chute having the repulsion plate is 4.2 m, the raw material deposition level in the furnace at the start of raw material charging is 7.55 m vertically below the turning and tilting center of the distribution chute, and the inside of the blast furnace. Ore and coke were deposited in. At this time, the distance d from the center position of the tilt / rotation of the distribution chute to the deposition surface level of the raw material in the furnace at the start of charging the raw material, the furnace opening radius Ro, and the angle α determined by the above (1) are 36.6. It becomes °.

When charging coke, start charging after setting the tilt angle of the chute to 54.5 °, set the turning speed to 10.0 to 14.0 rpm, and gradually reduce the tilt angle until coke is deposited in the center of the furnace. I charged it.

In Invention Examples 1 to 15, the shoot length of the distribution chute having the repulsion plate is 4.2 m, and the raw material deposition level in the furnace at the start of raw material charging is 7.55 m vertically below the center position of the tilting / turning of the distribution chute. Then, ore and coke were deposited in the blast furnace, and the blast furnace was operated.

Also in Invention Examples 1 to 15, the distance d to the center position of the tilting / turning of the distribution chute and the deposition surface level of the raw material in the furnace at the start of charging the raw material, the furnace opening radius Ro, and the angle determined by the above (1). α becomes 36.6 °.

When charging coke, the tilt angle of the distribution chute at the start of charging is gradually reduced as the turning speed increases, and after the start of charging, the tilt angle is gradually reduced until coke is deposited in the center of the furnace. I charged it. The turning speed of the distribution chute was 10.5 to 14.0 rpm. The operating conditions and operating results of this invention example and comparative example are shown in Tables 5 and 6 below. The coke deposition angle at the furnace wall was calculated from the inclination angle from the furnace wall to 1.8 m in the profile data of the charged material after the coke was charged.

比較例１では、原料装入開始時の炉内の原料堆積レベルにおけるコークスの落下幅が大きく、炉壁部のコークス堆積角が２６．１°と小さかったのに対し、発明例１〜１５では炉壁部のコークス堆積角が２６．５°以上になった。この結果、炉壁部において［Ｏｒｅ／Ｃｏｋｅ］を低減させている領域の面積が小さくなり、炉内全体のガス利用率が向上し、発明例１〜１５の還元材比およびコークス比は、比較例１よりも低減した。

In Comparative Example 1, the falling width of coke at the raw material deposition level in the furnace at the start of charging the raw material was large, and the coke deposition angle of the furnace wall was as small as 26.1 °, whereas in Invention Examples 1 to 15, the coke deposition angle was small. The coke deposition angle of the furnace wall became 26.5 ° or more. As a result, the area of the region where [Ore / Cake] is reduced in the furnace wall is reduced, the gas utilization rate in the entire furnace is improved, and the reducing agent ratio and the coke ratio of Invention Examples 1 to 15 are compared. It was reduced compared to Example 1.

In Invention Examples 4 to 15 in which the turning speed of the distribution chute is 12.0 rpm or more, if the turning speed is the same, the tilt angle of the distribution chute is 1.36 α or more rather than the tilt angle of the distribution chute being less than 1.36 α. As a result, the coke deposition angle of the furnace wall increased, and the reducing agent ratio and coke ratio decreased. From this result, it was confirmed that the reducing agent ratio and the coke ratio in the blast furnace operation can be further reduced by setting the turning angle of the distribution chute to 1.36α or more.

Further, in Invention Examples 13 to 15 in which the turning speed of the distribution chute is 14.0 rpm or more, the tilt angle of the distribution chute is 1.41 α or more rather than the tilt angle of the distribution chute is less than 1.41 α. The coke deposition angle of the furnace wall increased, and the reducing agent ratio and coke ratio decreased. From this result, it was confirmed that the reducing agent ratio and the coke ratio in the blast furnace operation can be further reduced by setting the turning angle of the distribution chute to 1.41α or more.

10 Model equipment 12 Furnace top bunker 14 Hopper 16 Collective hopper 18 Distribution chute 20 Chute 21 Arrow 22 Repulsion plate 24 Sampling box 26 Containment section 30 Model equipment 32 Model furnace 40 Horizontal plane 42 Center position

Claims (6)

It is a method of charging raw materials for a bellless blast furnace in which iron source raw materials and charcoal materials are charged into the blast furnace by turning the distribution chute.
The distribution chute has a repulsion plate at the tip of the distribution chute that inclines downward from the transport direction of the distribution chute.
A method for charging raw materials for a bellless blast furnace, wherein the turning speed of the distribution chute is faster than 10.0 rpm. The method for charging raw materials for a bellless blast furnace according to claim 1, wherein the turning speed of the distribution chute is 12.0 rpm or more. The tilt angle of the distribution chute is 1.36α with respect to the distance d from the turning center of the distribution chute to the raw material deposition level in the furnace at the start of charging the raw material, the radius of the furnace mouth Ro, and the angle α determined by the following equation (1). The method for charging raw materials for a bellless blast furnace according to claim 2, as described above.
tanα = Ro / d ... (1) The method for charging raw materials for a bellless blast furnace according to claim 1, wherein the turning speed of the distribution chute is 14.0 rpm or more. The tilt angle of the distribution chute is 1.41α with respect to the distance d from the turning center of the distribution chute to the raw material deposition level in the furnace at the start of charging the raw material, the radius of the furnace mouth Ro, and the angle α determined by the following equation (1). The method for charging raw materials for a bellless blast furnace according to claim 4, as described above.
tanα = Ro / d ... (1) A blast furnace operating method for charging an iron source raw material and a carbonaceous material into the blast furnace by the method for charging raw materials for a bellless blast furnace according to any one of claims 1 to 5.

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