JP5696814B2 - Raw material charging method for bell-less blast furnace - Google Patents

Description

  The present invention relates to a raw material charging method into a bell-less blast furnace capable of controlling the gas flow in the vicinity of the furnace wall without significantly increasing the reducing material ratio of the blast furnace.

  The bell-less blast furnace is a blast furnace in which a bell-less charging apparatus having a turning chute as a raw material charging apparatus is provided at the top of the furnace.

  FIG. 1 is a diagram schematically illustrating an apparatus configuration at the top of a bell-less blast furnace and a raw material deposition state in the blast furnace. As shown in FIG. 1, in a bell-less blast furnace, iron ore, sintered ore, lump ore, pellets, scrap, reduced iron, etc. (hereinafter collectively referred to as “ore”) and reducing material coke ( Ore and coke are collectively referred to as “raw material”) and are alternately layered in the furnace of the blast furnace 2 by the swivel chute 1 and auxiliary fuel such as pulverized coal is fed into the furnace along with hot air from the tuyeres at the bottom of the furnace Infuse. The charged raw material (charged material), which is the raw material charged in the blast furnace, is heated and reduced by the rising high temperature gas and coke in the charged material while gradually descending the furnace from the top of the furnace. Melts into pig iron and is discharged from the tap hole in the side wall of the furnace bottom.

  In the bell-less blast furnace, the charge distribution operation is performed by turning the turning chute 1 while charging the coke and ore into the furnace, and the coke and ore in the direction of the furnace mouth radius 4 at the raw material stock level 3. This is done by controlling the drop position. Here, tilting means changing the angle formed by the central axis 1a of the turning chute and the central axis 2a in the vertical direction of the blast furnace during turning. Usually, the turning chute is arranged on the furnace wall side at the start of charging, and is then operated so as to tilt gradually toward the furnace center side.

  In a blast furnace, a series of charging operations for forming a coke layer and an ore layer (mainly ore but may include small and medium-sized coke) is referred to as charging. Conventionally, one charge of raw material is charged by continuously charging one batch of coke and one batch of ore from the furnace wall side to the center side while tilting the swivel chute. It was.

  For stable operation of the blast furnace, it is important to stabilize the lowering of the charge and the gas flow in the furnace to maintain good air permeability. Therefore, the distribution of the mass ratio (hereinafter referred to as “O / C”) of the ore and coke in the radial direction of the furnace of the raw material deposited in the furnace and the particle size distribution are controlled along with the operation of the blowing conditions from the tuyere. Operation is performed. Since the average particle size of the coke charged in the furnace is larger than that of the ore, the O / C distribution and the particle size distribution of the ore and coke in the furnace radial direction are controlled (that is, the distribution of the charge is manipulated). Thus, the gas flow distribution from the lower part of the furnace to the upper part of the furnace can be controlled.

  In order to ensure a stable gas flow, it is preferable to keep the O / C at the center low (that is, increase the coke ratio). Moreover, in order to improve the reaction efficiency of the whole furnace, the furnace wall from the furnace middle part (the part between the area near the center and the area near the furnace wall in the furnace) that accounts for a large proportion of the cross-sectional area of the furnace port It is preferable to maintain the O / C at the high side.

  In order to make it easy to obtain such an O / C distribution, the coke and the ore are divided and charged, respectively. FIG. 1 shows a deposition state 5 of one charge of raw material in which coke and ore are divided into two batches and a total of four batches are charged.

  A first batch of coke (hereinafter referred to as “first charging batch”) 5a is charged from the furnace wall portion to the middle portion, and the thickness of the first charging batch 5a is greater in the vicinity of the center of the furnace. The second batch of coke (hereinafter referred to as “second charging batch”) 5b is charged so as to increase. On the first and second charging batches 5a and 5b, a first batch of ore (hereinafter referred to as "third charging batch") 5c is charged from the furnace wall to the middle of the furnace. On the wall side, a second batch of ore (hereinafter referred to as “fourth charging batch”) 5d is charged. Depending on the relationship between the thickness of the coke layer composed of the first and second charging batches 5a and 5b and the thickness of the ore layer consisting of the third and fourth charging batches 5c and 5d, the O / C at the center of the furnace is The gas flow is stably secured by being kept at a low level, and the O / C from the furnace middle part to the furnace wall side is kept at a high level, thereby improving the reaction efficiency of the whole furnace.

  Usually, the ore batch is mixed with so-called small and medium-sized coke having a particle size smaller than that of the coke charged in the coke batch. This is because it can be expected that the reaction is promoted by the close arrangement of the ore and the coke, and that the coke plays a role as an aggregate (spacer) when the ore is softened and fused. The particle size of the small and medium-sized coke has a lower limit of about 5 mm, and the upper limit is about 35 to 40 mm although it varies depending on the coke particle size charged in the coke batch.

  By the way, in a blast furnace, zinc-containing compounds may solidify on the inner wall of the upper part of the furnace, and metal iron and slag may solidify on the inner wall from the furnace belly part to the lower part of the furnace to form deposits. If such furnace wall deposits grow excessively, the descending of the charge and the gas flow may become unstable, which may hinder the stable operation of the blast furnace. Furthermore, if the furnace wall deposits fall off irregularly and fall to the bottom of the furnace, the fallen deposits can cause insufficient heat in the furnace and even cause serious operational troubles such as furnace cooling. . For this reason, in order to maintain the stable operation of a blast furnace, it is important to suppress the formation of furnace wall deposits.

  In order to suppress the formation of furnace wall deposits, generally, a charge distribution operation for controlling the O / C on the furnace wall side relatively low is directed. By such control, the gas flow on the furnace wall side is strengthened and the heat level is maintained at a high level, so that the formation of deposits can be suppressed.

However, on the other hand, as the gas flow becomes stronger, the reaction time between the gas rising in the furnace and the charged material becomes shorter, so that a decrease in O / C leads to a decrease in reaction efficiency. In the conventional raw material charging method using a swirl chute, for the purpose of suppressing the formation of furnace wall deposits, when increasing the amount of coke charged to the furnace wall side, only O / C near the furnace wall is used. It is difficult to control independently. This is because not only the vicinity of the furnace wall, but also the O / C over a wide range including the furnace middle part having a large proportion of the sectional area of the furnace port is reduced. For this reason, the reaction efficiency of the entire furnace is reduced, and the latent heat of the gas discharged from the top of the furnace to the outside of the furnace is increased, so that the reducing material ratio is increased to compensate for this, and the pig iron manufacturing cost is reduced. To rise. This is also not preferable from the viewpoint of reducing CO ₂ emissions.

  Therefore, in order to realize operation at a low reducing material ratio while suppressing the formation of furnace wall deposits, a technique for independently controlling O / C only in the vicinity of the furnace wall is necessary. 1 to 3 disclose a method therefor.

  In Patent Document 1, a new ancillary facility is installed by charging a small coke on an ore layer in the range of 500 mm from the furnace wall, preferably as a mixture with fine-grained sintered ore having a particle size of 1 to 5 mm. It is possible to control O / C near the furnace wall without the need. However, it is difficult to stably deposit small coke on a terrace in a range of 500 mm from the furnace wall.

  In Patent Document 2, it is possible to independently control O / C in the vicinity of the furnace wall by charging the raw material with the cylindrical member installed along the outer periphery of the furnace port. However, since the control range is fixed depending on the installation position of the cylindrical member, the degree of freedom in operation is small.

  In Patent Document 3, a raw material charging system different from the normal route and an auxiliary bunker are installed, and the coke is discharged from the auxiliary bunker in accordance with the ore discharge from the normal bunker, so that the O / C in the vicinity of the furnace wall is independent. Control is possible. However, in this method, since it is necessary to control the ore discharge from the bunker and the coke discharge from the auxiliary bunker according to the tilt position of the turning chute, the control becomes complicated.

JP-A-8-239705 JP 2005-314771 A JP 2009-62576 A

Kaoru Nakano, Kohei Sunahara and Takanobu Inada, “Advanced Supporting System for Burden Distribution Control Blast Furnace Ip. 538-543

  As described above, in order to suppress the formation of deposits on the furnace wall, if an attempt is made to increase the amount of coke charged near the furnace wall by a normal charge distribution operation, not only the vicinity of the furnace wall but also the middle part of the furnace is included. Since O / C over a wide range is lowered, it is difficult to achieve both low-reducing material ratio operation. In order to achieve both of these, it is necessary to independently control only the O / C near the furnace wall.

  In the methods described in the above-mentioned Patent Documents 2 and 3, since it is necessary to install a new incidental facility in a normal bellless charging device, it is disadvantageous in terms of installation cost and maintenance cost. A charging method that does not require any additional facilities is desirable.

  Further, in the method described in Patent Document 1 described above, the range of 500 mm from the furnace wall is defined as the charging range of the small coke, but the relative size of the small coke in the in-furnace radial direction is determined by the furnace port radius of the blast furnace. The position changes. For example, depending on the volume of the blast furnace and the charging conditions, the width of the raw material flow generally charged through the swivel chute is often 500 mm or more at the stock level, and is on a terrace in the range of 500 mm from the furnace wall. It is difficult to deposit the raw material stably. Since the raw material is small coke and fine-grained sintered ore, if some raw material overflows from the terrace and flows to the center side, it may obstruct the gas flow in the center or cause fluctuations in the gas flow. .

  This invention is made | formed in view of such a condition, and provides the raw material charging method to the bell-less blast furnace which can control O / C only in the vicinity of a furnace wall independently, without requiring new incidental equipment. The purpose is that.

  Usually, in many blast furnaces, in order to strengthen the gas flow in the central part in order to continue stable operation, the O / C on the central side is kept at a low level and from the middle part of the furnace where the cross-sectional area is large. The reduction ratio can be reduced by maintaining the O / C on the furnace wall side at a high level.

  On the other hand, in a situation where the deposits on the furnace wall grow excessively and hinder the stable operation of the blast furnace, as a method for suppressing the formation of deposits or removing the deposits, an O / C near the furnace wall is used. It is effective to reduce. However, as described above, in the normal method of continuously charging the raw material from the furnace wall side toward the center side while tilting the turning chute, only the O / C near the furnace wall can be controlled independently. It is difficult and O / C falls in a wide range including the furnace middle part. Therefore, although the formation of the deposit on the furnace wall is suppressed by strengthening the gas flow on the furnace wall side, the reaction efficiency of the entire furnace is lowered, leading to a significant increase in the reducing material ratio.

  Therefore, if the O / C only in the vicinity of the furnace wall can be controlled and lowered independently without greatly changing the normal O / C distribution in the furnace radial direction from the furnace center to the middle part, formation of furnace wall deposits is possible. , And a significant increase in the reducing material ratio can be suppressed.

  Therefore, the present inventors have made various studies on a raw material charging method for a bell-less blast furnace that can independently reduce O / C in the vicinity of the furnace wall. As a result, the raw material is charged from the chute to form a raw material deposition layer with an apex in the middle of the furnace, and the segregation effect due to the raw material slope from the apex (hereinafter referred to as “deposition apex”) to the furnace wall As a result, the present inventors have found a raw material charging method that can independently control only the O / C in the vicinity of the furnace wall without requiring any additional incidental equipment.

The present invention has been made on the basis of such examination results, and the gist thereof is the following raw material charging method to the bell-less blast furnace.
That is, a raw material charging method into a bell-less blast furnace in which a coke layer and an ore layer are alternately deposited, and the raw material charging from the middle part of the furnace to the furnace wall is performed with coke batch, ore and coke. The mixture batch and the ore batch are charged in this order,
The coke batch is deposited such that the coke surface has a deposition apex in the range of dimensionless furnace mouth radius 0.6 to 0.8, and forms a raw material deposition slope inclined from the deposition apex to the furnace center and the furnace wall. ,
The mixture batch of ore and coke is charged with the charging drop point as the furnace wall side from the top of the coke deposition,
The ore batch is a raw material charging method into a bell-less blast furnace characterized in that the charging and dropping point is charged within a range of a dimensionless furnace port radius of 0.5 to 0.9.
The “dimensionless furnace port radius” is an index representing the position of the raw material charging surface (raw material stock level) with respect to the furnace center, and the distance from the furnace center to the position is divided by the furnace port radius. It is an index standardized by. The furnace center is represented by 0 and the furnace wall is represented by 1.
In addition, the “furnace intermediate part” herein refers to a range of dimensionless furnace port radius of 0.5 to 0.8.

  In the raw material charging method to the bell-less blast furnace of the present invention, the charging amount of the mixture batch of ore and coke is made smaller than that of the ore batch, and the charging drop point of the mixture batch of ore and coke is set. It is desirable to adopt an embodiment in which charging is performed in a range of a dimensionless furnace port radius of 0.9 or less on the furnace wall side with respect to the deposition apex formed by charging the coke batch.

  Moreover, in the raw material charging method to the bell-less blast furnace of this invention, it replaces with the mixture batch of the said ore and coke, and can take embodiment which charges the batch only of coke.

According to the raw material charging method to the bell-less blast furnace of the present invention, the O / C only in the vicinity of the furnace wall can be independently controlled and reduced without requiring any additional incidental equipment. Thereby, the gas flow by the side of a furnace wall can be strengthened, formation of furnace wall deposits can be suppressed or deposits can be removed. In this raw material charging method, since the ratio of reducing material in the blast furnace is not significantly increased, it is possible to suppress a decrease in productivity, an increase in pig iron production cost, and an increase in CO ₂ emissions.

FIG. 1 is a schematic diagram showing an apparatus configuration at the top of a bell-less blast furnace and a raw material deposition state in the blast furnace. 2A and 2B are diagrams showing calculation results of a raw material deposition profile using a simulation model. FIG. 2A is a comparative example, and FIG. 2B is an example of the present invention. FIG. 3 is a diagram showing a calculation result by a simulation model of the O / C distribution in the furnace radial direction. FIG. 4 is a diagram showing a calculation result by a simulation model of the distribution in the furnace of ore and coke in the ore batch by the raw material charging method of the present invention. FIG. 5 is a diagram showing a raw material deposition profile in a model experiment, in which (a) is a comparative example and (b) is an example of the present invention. FIG. 6 is a diagram showing the O / C distribution in the furnace radial direction in the model experiment.

  As described above, the raw material charging method of the present invention is premised on the raw material charging method in which a coke layer and an ore layer are usually deposited alternately in a bell-less blast furnace.

  In the raw material charging method of the present invention, when the coke layer and the ore layer are alternately deposited, the raw material charging from the middle part of the furnace to the furnace wall, the coke batch, the mixture batch of ore and coke, ore batch Insert in order. “About the raw material charging from the middle part of the furnace to the furnace wall” is intended to pay attention to the raw material charging in the furnace inner region excluding the center of the furnace or the middle part of the furnace. For example, the coke is charged as a first charging batch 5a from the furnace wall portion to the middle portion, and then charged as a second charging batch 5b in the vicinity of the center of the furnace, as in the conventional case (see FIG. 1). )be able to.

  First, the coke batch is charged, and when the coke charging is completed, the surface of the coke layer has a deposition apex in the range of dimensionless furnace port radius 0.6 to 0.8, and from the deposition apex to the furnace center and the furnace wall. The coke layer is deposited so as to form an inclined raw material deposition (coke layer) slope. Subsequently, the batch of the mixture is charged such that the charging and dropping point of the mixture batch of ore and coke is set to the furnace wall side from the deposition top of the coke layer.

  When the coke charging is completed, the coke layer surface has a deposition vertex in the range of the predetermined dimensionless furnace port radius, and the coke layer is deposited so as to form a raw material deposition slope inclined from the deposition vertex to the furnace center. Aims to enhance the central gas flow by promoting particle size segregation on the slope and depositing a raw material having a large particle size on the furnace center side. The reason why the slope inclined from the top of the deposition to the furnace wall is formed is to deposit particles having a large particle size in the vicinity of the furnace wall by utilizing the particle size segregation phenomenon on the slope.

  For this reason, it is not preferable to form the deposition vertex on the surface of the coke layer too close to the center. Moreover, it is possible to prevent the raw material of the mixture batch of ore and coke charged after the coke layer formation from flowing into the center side, and to effectively use the particle size segregation on the slope from the top of the deposition to the furnace wall. preferable. From these viewpoints, the deposition peak of the coke layer is formed in a range of dimensionless furnace port radius of 0.6 to 0.8. Usually, a small batch of coke is mixed in a mixture batch of ore and coke. In this case, since the particle size and density are different, ore and coke are separated, and coke having a large particle size and low density with respect to the ore is deposited near the furnace wall. Thereby, O / C of the furnace wall vicinity can be reduced.

  Therefore, the charging position of the mixture batch of ore and coke on the coke slope is important. This charging position is on the furnace wall side with respect to the deposition top of the coke layer. However, if the charging position is too close to the furnace wall, the segregation effect cannot be enjoyed and the O / C in the vicinity of the furnace wall cannot be reduced. A range of 9 or less is desirable.

  In the method described in Patent Document 1 described above, a mixture of ore and coke is charged on the ore layer formed earlier, whereas in the raw material charging method of the present invention, it is applied on the coke layer. The mixture of ore and coke is charged, for example, as a second batch. Therefore, in the raw material charging method of the present invention, ore having an average particle size smaller than that of coke tends to stay at the charging and falling point by filling the voids of the coke layer, and coke having an average particle size larger than ore is on the slope. It becomes easy to deposit on the furnace wall side away from the dropping point due to segregation.

  Subsequently, the ore batch is charged. As usual, this ore batch is charged with the charging and dropping point at a dimensionless furnace port radius of 0.5 to 0.9 while tilting the turning chute from the furnace wall side to the center side. Since the charge of the mixture batch of ore and coke deposited on the furnace wall side becomes a barrier to the deposition on the furnace wall side of the ore batch, the O / C near the furnace wall does not increase extremely, Kept low.

  In the raw material charging method of the present invention, the charging amount of the ore and coke mixture batch is made smaller than that of the ore batch, and the charging and dropping point of the ore and coke mixture batch is set after the completion of coke charging. It is desirable to adopt an embodiment in which charging is performed within a range of a dimensionless furnace port radius of 0.9 or less on the furnace wall side from the apex.

  The charging amount of the ore and coke mixture batch is set to be smaller than that of the ore batch so that the raw material charged in the ore and coke mixture batch does not flow from the top of the coke layer into the furnace center. It is to do.

  Charging a mixture batch of ore and coke facilitates the reaction by contacting the ore and coke as grains rather than as a layer (ie, placing the ore and coke close together) This is because the gas flow on the furnace wall side is strengthened by functioning as an aggregate (spacer), and the formation of furnace wall deposits is more effectively suppressed. The above-mentioned effects are the same regardless of whether the coke mixed with the ore in the mixture of ore and coke is a small medium coke or a large coke (particle size coke charged in a normal coke batch). Is obtained.

  In addition, if a mixture of ore and coke is charged, the O / C in the vicinity of the furnace wall can be controlled by adjusting the amount of coke, thus ensuring operational freedom.

  The ore and coke mixture batch charging drop point is closer to the furnace wall than the top of the deposit after completion of coke charging and the dimensionless furnace port radius is 0.9 or less. This is because if the batch interior position of the mixture batch with coke is too close to the furnace wall, the segregation effect on the coke slope cannot be obtained, and ore accumulates with the coke near the furnace wall, increasing O / C. .

  Moreover, in the raw material charging method to the bell-less blast furnace of this invention, it replaces with the mixture batch of the said ore and coke, and can take embodiment which charges the batch only of coke.

  In this case, it is not necessary to consider the separation of ore and coke due to the particle size segregation effect on the sedimentary slope when charging a mixture batch of ore and coke. Moreover, it can be concentrated in the vicinity of the furnace wall. The maintenance of the controllability of O / C in the vicinity of the furnace wall and the securing of the operational freedom based thereon are the same as when charging a batch of ore and coke.

  In addition, since only coke is charged, the effect of promoting the reaction due to the proximity of the ore and coke cannot be expected, but the formation of furnace wall deposits is suppressed or the deposits are removed by strengthening the gas flow on the furnace wall side. Can be expected to have an immediate effect.

As described above, according to the raw material charging method of the present invention, the O / C in the vicinity of the furnace wall is independently controlled and reduced without requiring the installation of new equipment and the maintenance cost associated therewith. be able to. By reducing the O / C in the vicinity of the furnace wall, the gas flow on the furnace wall side can be strengthened to suppress the formation of the furnace wall deposits or to remove the deposits. Further, since it becomes possible to reduce the O / C only in the vicinity of the furnace wall, the reduction ratio of the blast furnace is not significantly increased, the productivity is lowered, the pig iron manufacturing cost is increased, and the CO ₂ emission amount is reduced. Can be suppressed.

  The effect of the raw material charging method of the present invention was verified using the bell-less blast furnace charge distribution simulation model and the bell-less charging model apparatus described in Non-Patent Document 1 above.

Example 1
[Load distribution simulation]
The target blast furnace was a bell-less blast furnace with a furnace capacity of 5,370 m ³ , and one charge was composed of two batches of coke and two batches of ore based on the actual charge of the actual furnace. The charging amount per charge was 20.7 tons in total for the coke batch, and 140.7 tons in total for the ore batch including 4.1 ton (particle size 6 to 50 mm) of coke. One of the two batches of coke corresponds to a coke batch charged from the furnace intermediate part to the furnace wall ("first charge batch 5a" in FIG. 2 described below, hereinafter referred to as this term). . The two batches of ore are a mixture batch of the ore and coke (hereinafter referred to as “third charging batch 5c”) and an ore batch (hereinafter referred to as “fourth charging batch 5d”). is there. In the embodiment of the present invention, the mass ratio of the third charging batch 5c and the fourth charging batch 5d was 10:90.

  FIG. 2 is a diagram illustrating a calculation result of a raw material deposition profile using a simulation model. (A) is a comparative example, when raw material charging is performed by normal operation, (b) is an example of the present invention, and is a case where raw material charging is performed by the method of the present invention. In FIG. 2, one charge (ie, first and second charge batches 5a, 5b of coke, and third and fourth charge batches 5c, 5d of ore; third charge batch 5c contains coke). The raw material deposition profile is shown.

  In the raw material deposition profile of the comparative example shown in FIG. 2 (a), while maintaining the central gas flow stable and improving the reaction efficiency from the furnace middle part to the furnace wall side, the O / C at the center part is kept low. The O / C from the furnace middle part to the furnace wall side is maintained at a high level.

  On the other hand, in the example of the present invention shown in FIG. 2 (b), the coke layer (first charging batch 5a) formed before ore charging has a deposition apex 6 at a dimensionless furnace port radius 0.7. The coke layer was deposited so as to form a raw material slope inclined from the deposition apex to the furnace center and the furnace wall. The raw material of the third charging batch 5c charged after formation of the coke layer is a mixture of ore and coke, and the raw material supplied from the swirl chute is coke from the viewpoint of preventing the raw material of the batch from flowing into the center. The tilt angle of the swivel chute was adjusted so as to be inserted at a dimensionless radius of 0.9 on the furnace wall side of the layer deposition apex. By adopting such a charging method, ore and coke are separated by particle size segregation on the slope of the coke layer from the deposition apex of the middle part of the furnace to the furnace wall, and coke is deposited near the furnace wall.

  Subsequently, the fourth charging batch 5d to be charged has a charging drop point in the range of dimensionless furnace port radius of about 0.6 to 0.8, while tilting the swivel chute from the furnace wall side to the furnace middle part. I entered. The raw material of the third charging batch 5c deposited on the furnace wall side becomes a barrier against the deposition of the raw material of the fourth charging batch 5d on the furnace wall side, so the O / C in the vicinity of the furnace wall is kept low. .

  FIG. 3 is a diagram showing a calculation result by a simulation model of the O / C distribution in the furnace radial direction, and the O / C at the top of the blast furnace by the raw material charging method (comparative example) in the normal operation shown in FIG. FIG. 3 is a diagram comparing the radial distribution of the O / C and the radial distribution of O / C by the raw material charging method of the present invention shown in FIG. 2 (b). From FIG. 3, in the raw material charging method according to the present invention in which the deposition apex position of the coke layer is a dimensionless furnace port radius 0.7, and the raw material charging position of the third charging batch is the dimensionless furnace port radius 0.9. Compared to the raw material charging method in normal operation, the O / C in the vicinity of the furnace wall decreases without significant change from the furnace center to the middle part of the furnace, and the desired O / C distribution state It can be seen that

  FIG. 4 illustrates a raw material charging method of the present invention in which the deposition apex position of the coke layer is a dimensionless furnace port radius 0.7 and the furnace interior charging position of the third charging batch is a dimensionless furnace port radius 0.9. It is a figure which shows the calculation result by the simulation model of the distribution in the furnace of the said ore and coke of the said batch. From this figure, it can be seen that a large amount of coke accumulates near the furnace wall due to particle size segregation on the coke slope.

  As a result of the verification using the above-mentioned Berles blast furnace charge distribution simulation model, the effect of the raw material charging method of the present invention (that is, the O / C in the vicinity of the furnace wall can be independently controlled) was confirmed.

(Example 2)
[Bellless insertion model experiment]
The effect of the raw material charging method of the present invention was verified using a bell-less charging model device having a scale of 1 / 5.6 of a furnace volume of 5,370 m ³ .

  The particle size of the raw material used in the experiment was approximately 5.6 times the actual furnace size, and the charge amount per charge was the sum of coke batches (first and second charge batches) according to a similar rule. 146 kg, ore batch (3rd and 4th charging batch) was 801 kg in total including 23 kg of coke (particle size 1-10 mm). In the embodiment of the present invention, the mass ratio of the third charging batch and the fourth charging batch was 10:90.

  In the model experiment, when the raw material charging is performed by the method of the present invention, as in the case of Example 1, the deposition apex position of the coke layer is set to a dimensionless furnace port radius of 0.7, and the charging of the third charging batch is performed. The entry position was a dimensionless furnace port radius of 0.9.

  FIG. 5 is a diagram showing a raw material deposition profile in a model experiment. (A) is a comparative example, when raw material charging is performed by normal operation, (b) is an example of the present invention, and is a case where raw material charging is performed by the method of the present invention. The raw material deposition profile in the furnace was continuously measured using a laser distance meter. FIG. 5 shows a one-charge material deposition profile.

  From FIG. 5, both the case where the raw material charging is performed by the normal operation (comparative example) and the case where the raw material charging is performed by the method of the present invention are almost the same as the calculation result by the above-mentioned charge distribution simulation model. It can be seen that this is a raw material deposition profile.

  FIG. 6 is a diagram showing the O / C distribution in the furnace radial direction in the model experiment. The O / C radius at the top of the blast furnace by the raw material charging method (comparative example) in the normal operation shown in FIG. It is the figure which compared directional distribution and radial direction distribution of O / C by the raw material charging method of this invention shown to (b). From FIG. 6, similarly to the calculation result by the simulation model (see FIG. 3), when the raw material charging method is performed by the raw material charging method of the present invention, compared to the raw material charging method in normal operation, It can be seen that the O / C in the vicinity of the furnace wall is lowered without a large change in the O / C in the middle of the furnace from the furnace center.

  As a result of the verification using the above bell-less charging model apparatus, it was confirmed that the effect of the raw material charging method of the present invention (that is, O / C in the vicinity of the furnace wall can be controlled independently).

  According to the raw material charging method to the bell-less blast furnace of the present invention, the O / C only in the vicinity of the furnace wall can be controlled and lowered independently. Moreover, since formation of furnace wall deposits can be prevented without significantly increasing the reducing material ratio of the blast furnace, it is possible to suppress a decrease in productivity, an increase in pig iron manufacturing cost, and the like. Therefore, the present invention can be effectively used when charging the raw material into the bell-less blast furnace.

1: turning chute, 1a: central axis of turning chute,
2: blast furnace, 2a: central axis of blast furnace,
3: Raw material stock level, 4: Furnace port radius,
5: 1 charged raw material, 5a: first charging batch,
5b: second charging batch, 5c: third charging batch,
5d: 4th charging batch,
6: Coke layer deposition apex

Claims (3)

A raw material charging method for a bell-less blast furnace in which a coke layer and an ore layer are alternately deposited,
Regarding raw material charging from the middle part of the furnace to the furnace wall, coke batch, ore and coke mixture batch, ore batch are charged in this order,
In the coke batch, the coke surface has a deposition apex in the range of a dimensionless furnace mouth radius of 0.6 to 0.8, and the coke is formed so as to form a raw material deposition slope inclined from the deposition apex to the furnace center and the furnace wall. Deposit,
The mixture batch of ore and coke is charged with the charging drop point as the furnace wall side from the top of the coke deposition,
A raw material charging method for a bell-less blast furnace, wherein the ore batch is charged with a charging drop point in a range of a dimensionless furnace port radius of 0.5 to 0.9. Reducing the charge of the ore and coke mixture batch to less than the charge of the ore batch;
The charging and dropping point of the mixture batch of ore and coke is charged at the furnace wall side of the deposition apex formed by charging the coke batch, and the dimensionless furnace port radius is 0.9 or less. The method for charging a raw material into a bell-less blast furnace according to claim 1, wherein: The raw material charging method to the bell-less blast furnace according to claim 1 or 2, wherein a batch of only coke is charged instead of the mixture batch of ore and coke.

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