WO2013172046A1 - Method for loading raw material into blast furnace - Google Patents
Method for loading raw material into blast furnace Download PDFInfo
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- WO2013172046A1 WO2013172046A1 PCT/JP2013/003172 JP2013003172W WO2013172046A1 WO 2013172046 A1 WO2013172046 A1 WO 2013172046A1 JP 2013003172 W JP2013003172 W JP 2013003172W WO 2013172046 A1 WO2013172046 A1 WO 2013172046A1
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- WIPO (PCT)
- Prior art keywords
- raw material
- coke
- blast furnace
- ore
- furnace
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B7/00—Blast furnaces
- C21B7/18—Bell-and-hopper arrangements
- C21B7/20—Bell-and-hopper arrangements with appliances for distributing the burden
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
- C21B5/001—Injecting additional fuel or reducing agents
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
- C21B5/007—Conditions of the cokes or characterised by the cokes used
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
- C21B5/008—Composition or distribution of the charge
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B1/00—Shaft or like vertical or substantially vertical furnaces
- F27B1/10—Details, accessories, or equipment peculiar to furnaces of these types
- F27B1/20—Arrangements of devices for charging
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D3/00—Charging; Discharging; Manipulation of charge
- F27D3/0033—Charging; Discharging; Manipulation of charge charging of particulate material
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D3/00—Charging; Discharging; Manipulation of charge
- F27D3/10—Charging directly from hoppers or shoots
Definitions
- the present invention relates to a raw material charging method for a blast furnace in which the raw material is charged into the furnace with a swirl chute, and in particular, aims to achieve a uniform mixing layer of the ore raw material and coke.
- a blast furnace generally charges raw materials such as sintered ore, pellets, and massive ore and coke in layers from the top of the furnace, and flows combustion gas from the tuyere to obtain pig iron.
- the coke and ore raw material which are the charged raw materials for the blast furnace, descend from the top of the furnace to the lower part of the furnace, and ore reduction and raw material temperature rise occur.
- the ore raw material layer is gradually deformed while filling the gaps between the ore raw materials due to the temperature rise and the load from above, and the lower part of the shaft part of the blast furnace has a very high resistance to gas and almost no gas flows. Form a layer.
- raw material charging into a blast furnace is performed by alternately charging ore raw materials and coke, and in the furnace, ore raw material layers and coke layers are alternately layered. Further, in the lower part of the blast furnace, there is a region called a cohesive zone where an ore raw material layer having a large ventilation resistance softened and fused with ore and a coke slit having a relatively small ventilation resistance derived from coke are mixed.
- the air permeability of this cohesive zone has a great influence on the air permeability of the entire blast furnace, and the productivity in the blast furnace is limited.
- a low coke operation it is considered that the coke slit becomes extremely thin because the amount of coke used is reduced.
- Patent Document 2 proposes that ore and coke are separately stored in a bunker at the top of the furnace, and coke and ore are mixed and charged simultaneously.
- no particular consideration is given to the separation of coke and ore after the raw material is charged into the furnace, and there is concern about the separation of coke and ore due to segregation of coarse and fine particles after raw material charging. .
- Patent Document 3 in order to prevent the instability of the cohesive zone shape in the blast furnace operation and the decrease in the gas utilization rate near the center, and to improve the safe operation and thermal efficiency, the raw material charging method in the blast furnace is In addition, after all ore and all coke are thoroughly mixed, they are charged into the furnace.
- Patent Document 3 although a blast furnace having no coke slit is described, a specific raw material charging method in the blast furnace is not mentioned, and a method for controlling the charge mixture rate is not described. It is unknown.
- Patent Document 4 As a raw material charging method to improve the ventilation resistance without the presence of coke slits, ⁇ A method of operating a blast furnace in which ore raw materials such as sintered ore, pellets, massive ore and blast furnace charging raw materials of coke are charged into the blast furnace with a rotating chute, When charging the blast furnace charging raw material into the blast furnace, a central coke layer was formed in the axial center portion, and the ore raw material and coke were mixed so as not to generate a coke slit outside the central coke layer. A raw material charging method for a blast furnace, wherein a mixed layer is formed. " Proposed.
- Patent Document 4 has significantly improved the air permeability in the blast furnace, enabling stable blast furnace operation.
- the present invention relates to an improvement of the technique described in Patent Document 4 described above, and at the time of forming a mixed layer, it is intended to achieve further uniformization and thereby enable more stable blast furnace operation. It is.
- the inventors have made various studies in order to achieve further uniformity in forming the mixed layer in the blast furnace.
- the present inventors have obtained a novel finding that the homogenization of the mixed layer is greatly improved by increasing the discharge rate of the mixed raw material into the blast furnace.
- the present invention is based on the above findings.
- the gist configuration of the present invention is as follows. 1.
- the blast furnace operation method of charging ore raw materials such as sintered ore, pellets, massive ore and blast furnace charging raw materials of coke into the blast furnace using a rotating chute When a mixed layer is formed in a predetermined region in the blast furnace by charging the mixed raw material and the coke into the blast furnace, the discharge rate of the mixed raw material into the blast furnace is 1.5 t. / S or more,
- the raw material charging method to the blast furnace characterized by the above-mentioned.
- At least two furnace top bunkers disposed at the top of the blast furnace, and a collecting hopper disposed at a discharge port of each furnace top bunker and mixing raw materials discharged from the furnace top bunker to supply the swirl chute
- One or two of the furnace top bunker stores either or both of the ore raw material or the mixed raw material obtained by mixing the ore raw material and the coke, and stores them in one of the remaining furnace top bunkers.
- the coke and the ore raw material and / or mixed raw material are discharged simultaneously from the furnace top bunker, mixed with the collecting hopper, and mixed into the swivel chute.
- the mixed raw material in which the ore raw material and coke are mixed into the blast furnace is charged and the mixed layer is formed in the blast furnace, it is possible to achieve a more uniform mixed layer, so that it is more stable. It becomes possible to carry out the blast furnace operation.
- the ore raw material and coke mixed raw material are stored in the furnace top bunker 12b, only the coke is stored in the furnace top bunker 12a, and only the ore raw material is stored in the furnace top bunker 12c. Yes.
- the coke amount is preferably adjusted to 30% by mass or less of the total coke amount.
- the coke, mixed raw material and ore raw material discharged from the furnace top bunkers 12a to 12c after being adjusted to a predetermined flow rate by the flow rate adjusting gate 13 are collected into the collecting hopper 14. Then, the mixture is fed to the bellless type charging device 15 immediately below, and charged into the blast furnace 10 by the turning chute 16 of the bellless type charging device 15.
- the swirl chute 16 is revolved around the axis of the blast furnace 10 and at the same time is reversely tilted so as to tilt from the axial center of the blast furnace 10 toward the furnace wall. The case of making an input will be described. The case where the central coke layer is formed in the axial center portion of the blast furnace will be described.
- the turning chute 16 is controlled to reversely tilt so as to turn about the central axis of the blast furnace 10 and simultaneously tilt toward the furnace wall side from the axial center side of the furnace center of the blast furnace 10, and is discharged from the top bunker 12.
- Raw material charging is performed by a reverse tilt control method in which the charged blast furnace charging material is charged in the reverse direction from the furnace center side to the furnace wall side.
- the flow rate adjusting gates 13 of the furnace top bunkers 12b and 12c are closed, and the flow rate adjusting gate 13 of only the furnace top bunker 12a is opened. Only the coke stored in the furnace top bunker 12a is supplied to the turning chute 16, and a central coke layer 12d is formed at the axial center as shown in FIG.
- the swiveling chute 16 is gradually tilted in the horizontal direction, and when the formation of the central coke layer 12d is completed, the flow rate adjusting gates 13 of the remaining two furnace top bunkers 12b and 12c are opened at a predetermined ratio,
- the coke discharged from the bunker 12a and the mixed raw material discharged from the top bunker 12b and / or the ore raw material discharged from the top bunker 12c are simultaneously supplied to the collecting hopper 14. For this reason, the coke and the ore raw material are completely mixed by the collecting hopper 14 and then supplied to the swivel chute 16, and as shown in FIG.
- the mixed layer 12e which does not produce a coke slit with a substantially uniform mixing ratio with the raw material is formed.
- the coke amount of the central coke layer 12d and the mixed layer 12e is such that the coke amount of the central coke layer 12d is about 5 to 30% by mass of the total amount of coke charged per charge, while the coke amount of the mixed layer 12e is It is set to about 70 to 95% by mass of the total coke amount.
- the region where the central coke layer is formed is preferably 0 or more and 0.3 or less in the dimensionless radius of the blast furnace where the blast furnace axial center part is 0 and the furnace wall part is 1. The reason for this is that by collecting a part of the coke in the core part of the furnace, the air permeability in the shaft part and thus the air permeability of the entire blast furnace can be effectively improved.
- the amount of coke charged to form the central coke layer is preferably about 5 to 30% by mass of the amount of coke charged per charge. This is because if the amount of coke charged to the shaft center portion is less than 5% by mass, the air permeability around the shaft center portion is not sufficiently improved, while more than 30% by mass of coke is concentrated on the shaft center portion. In this case, not only the amount of coke for use in the mixed layer is reduced, but also the amount of heat removed from the furnace body is increased due to excessive gas flow in the axial center.
- the content is preferably 10 to 20% by mass.
- layers composed of the central coke layer 12d and the mixed layer 12e are sequentially formed in the blast furnace 10 from the lower part to the upper part.
- the central coke layer 12d having a low ventilation resistance is formed from the lower portion of the blast furnace toward the upper portion of the blast furnace.
- the mixed layer 12e in which the coke and the ore raw material are mixed is formed around it.
- a furnace core tube 32 is disposed on the inner peripheral surface of a cylindrical furnace body 31, and a cylindrical heating heater 33 is disposed outside the furnace core tube 32.
- a graphite crucible 35 is disposed at the upper end of a cylindrical body 34 made of a refractory inside the furnace core tube 32, and a charging raw material 36 is charged into the crucible 35.
- a load is applied to the charged raw material 36 from above by a load loading device 38 connected via a punch bar 37 so as to be in the same level as the fused layer at the bottom of the blast furnace.
- a drop sampling device 39 is provided below the cylindrical body 34.
- the gas adjusted by the gas mixing device 40 is sent to the crucible 35 through the lower cylindrical body 34, and the gas that has passed through the raw material 36 in the crucible 35 is analyzed by the gas analyzer 41.
- the heating heater 33 is provided with a thermocouple 42 for controlling the heating temperature, and the crucible 35 is 1200 to 1500 by controlling the heater 33 with a control device (not shown) while measuring the temperature with the thermocouple 42. Heat to ° C.
- a mixture of 50 to 100% by mass of sintered ore and 0 to 50% by mass of massive iron ore was used as the ore of the charging raw material 36 charged in the crucible 35.
- FIG. 3 is a graph in which the relationship between the maximum pressure loss ratio and the mixing amount when the mixing amount of coke with respect to the ore is changed in the case where the size of the coke is different.
- the pressure loss was highest when coke was not mixed, whereas the addition of coke significantly reduced the airflow resistance, and this effect increased as the amount of coke increased.
- the reason for this is that mixing the coke suppresses the deformation of the ore and maintains the voids in the vicinity of the mixed coke, which suppresses the phenomenon in which the voids between the particles decrease due to the deformation of the ore and the ventilation resistance increases. It is thought that.
- the lump coke means a particle having a particle size of about 30 to 60 mm
- the small and medium lump coke means a particle having a particle size of about 10 to 30 mm
- ore raw materials usually have a particle size of about 5 to 25 mm.
- the particle size of the ore raw material is preferably 10 to 30 mm and the particle size of the coke is preferably 30 to 55 mm. Further, it is preferable that the particle size ratio (coke particle size / ore material particle size) is about 1.0 to 5.5.
- the inventors investigated the ratio of coke in the mixed layer suitable for reducing pressure loss, that is, improving air permeability (amount of coke / amount of ore raw materials).
- the mass ratio is about 7 to 25%. It turned out to be preferable. More preferably, it is in the range of 10 to 15%. Note that when a suitable ratio of coke in the mixed layer is converted to a ratio to the total amount of coke, it is about 20 to 95%.
- the inventors conducted an evaluation test of the mixing ratio of coke in the ore raw material using a charging model device that becomes 1/18 scale of an actual blast furnace simulating the top of the blast furnace as shown in FIG. It was.
- the raw material particle size is 1/18 times that of the actual blast furnace
- the raw material charging amount is 1/18 times
- the charging chute is The turning speed was 1/18 times.
- FIG. 4 shows the results of examining the change over time in the mixing ratio of coke in the charged raw material when ore and coke are mixed in a bunker or when ore and coke are discharged simultaneously from two bunker.
- the amount of ore and coke was constant, and the target mixing ratio was set to 0.05.
- the mixing rate increases in the early and late stages of discharge, and the mixing ratio decreases from the target value (0.05) in the middle of discharging. .
- the mixing ratio of coke in the ore showed a substantially constant value with respect to the target value. Therefore, it can be seen that co-discharge mixing can control the mixing ratio of coke with higher accuracy than mixing in a bunker.
- the inventors next investigated the change in the mixing ratio when the discharging speed at the time of simultaneous discharging was variously changed.
- the quality of the mixing rate was judged by the difference between the maximum mixing rate and the minimum mixing rate in the furnace radial direction.
- the obtained result is shown in FIG.
- the difference between the maximum mixing rate and the minimum mixing rate decreases as the material discharge rate increases. That is, it can be seen that the ore and coke can be mixed more uniformly by increasing the discharge rate of the raw material.
- the discharge speed to 1.5 t / s or more, the difference between the maximum mixing rate and the minimum mixing rate is greatly reduced, and is substantially constant at 1.8 t / s or more.
- the conventional general raw material discharge rate is about 0.8 to 1.3 t / s, and conventionally, no particular attention has been paid to this discharge rate.
- the reason why the difference between the maximum mixing ratio and the minimum mixing ratio is reduced by increasing the discharge rate of the charged raw material, that is, the uniformity of the mixed layer is not yet clearly clarified.
- the inventors speculate as follows.
- the segregation of the charged raw material is considered to occur because ore having a small particle size is easily affected by the unevenness of the raw material deposition surface when the flow of the charged raw material flows on the stationary raw material deposition surface.
- the charging speed is increased, the kinetic energy of the charging raw material during the movement of the deposition surface is increased, and the ore having a small particle size is suppressed.
- the discharge rate of the raw material is increased, the layer thickness of the charged raw material flow increases.
- the layer thickness of the charged raw material flow is increased, the ratio of particles in contact with the lower surface is relatively decreased, and the influence of unevenness on the lower surface is reduced. From the above, it is presumed that when the charging speed is increased, segregation of the charging raw material is suppressed and the uniformization of the mixed layer is achieved.
- the shaft pressure is closely monitored, and when the blast furnace charging according to the present invention is continuously performed, if an abnormality is detected in the shaft pressure, the raw material charging method is changed to the normal charging method. It is advantageous to switch to a method in which the ore raw material layer and the coke slit are formed separately, and then after switching to the charging method according to the present invention, once the shaft pressure abnormality is resolved, it is advantageous to operate. .
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Abstract
Description
この融着帯の通気性が高炉全体の通気性に大きく影響を及ぼしており、高炉における生産性を律速している。低コークス操業を行う場合、使用されるコークス量が減少することからコークススリットが限りなく薄くなることが考えられる。 Conventionally, raw material charging into a blast furnace is performed by alternately charging ore raw materials and coke, and in the furnace, ore raw material layers and coke layers are alternately layered. Further, in the lower part of the blast furnace, there is a region called a cohesive zone where an ore raw material layer having a large ventilation resistance softened and fused with ore and a coke slit having a relatively small ventilation resistance derived from coke are mixed.
The air permeability of this cohesive zone has a great influence on the air permeability of the entire blast furnace, and the productivity in the blast furnace is limited. When a low coke operation is performed, it is considered that the coke slit becomes extremely thin because the amount of coke used is reduced.
例えば、特許文献1においては、ベルレス高炉において、鉱石ホッパーのうち下流側の鉱石ホッパーにコークスを装入し、コンベア上で鉱石の上にコークスを積層し、炉頂バンカーに装入して、鉱石とコークスとを旋回シュートを介して高炉内に装入するようにしている。
しかしながら、特許文献1においては、炉頂バンカーにおいて鉱石とコークスとを混合させることから、炉頂バンカー内で偏析が生じてしまい、鉄鉱石とコークスとの混合比率を正確に維持することはできないという問題があった。 In order to improve the cohesive zone ventilation resistance, it is known that mixing coke into the ore raw material layer is effective, and many studies have been reported to obtain an appropriate mixing state. .
For example, in
However, in
しかしながら、原料が炉内に装入された後のコークスと鉱石の分離については特に考慮が払われてなく、原料装入後の粗粒と細粒の偏析によるコークスと鉱石の分離が懸念される。
However, no particular consideration is given to the separation of coke and ore after the raw material is charged into the furnace, and there is concern about the separation of coke and ore due to segregation of coarse and fine particles after raw material charging. .
しかしながら、特許文献3に記載された技術では、コークススリットがない高炉については記載されているが、高炉における具体的な原料装入方法については言及されてなく、装入物混合率の制御法が不明である。 Furthermore, in
However, in the technique described in
「焼結鉱、ペレット、塊状鉱石などの鉱石類原料及びコークスの高炉装入原料の高炉内への装入を旋回シュートで行う高炉の操業方法であって、
前記高炉装入原料を前記高炉に装入する際に、軸心部に中心コークス層を形成し、該中心コークス層の外側にコークススリットを生じさせないように前記鉱石類原料及びコークスを混合させた混合層を形成するようにしたことを特徴とする高炉への原料装入方法。」
を提案した。 By the way, the inventors, in Patent Document 4, as a raw material charging method to improve the ventilation resistance without the presence of coke slits,
`` A method of operating a blast furnace in which ore raw materials such as sintered ore, pellets, massive ore and blast furnace charging raw materials of coke are charged into the blast furnace with a rotating chute,
When charging the blast furnace charging raw material into the blast furnace, a central coke layer was formed in the axial center portion, and the ore raw material and coke were mixed so as not to generate a coke slit outside the central coke layer. A raw material charging method for a blast furnace, wherein a mixed layer is formed. "
Proposed.
その結果、混合原料の高炉内への排出速度を上昇させることによって、混合層の均一化が大幅に向上するという新規な知見を得た。
本発明は、上記の知見に立脚するものである。 Now, the inventors have made various studies in order to achieve further uniformity in forming the mixed layer in the blast furnace.
As a result, the present inventors have obtained a novel finding that the homogenization of the mixed layer is greatly improved by increasing the discharge rate of the mixed raw material into the blast furnace.
The present invention is based on the above findings.
1.焼結鉱、ペレット、塊状鉱石などの鉱石類原料及びコークスの高炉装入原料を、旋回シュートを用いて高炉内へ装入する高炉操業方法において、
前記鉱石類原料と前記コークスとを混合した混合原料として高炉内へ装入することにより、高炉内の所定領域に混合層を形成するに際し、前記混合原料の高炉内への排出速度を1.5t/s以上とすることを特徴とする高炉への原料装入方法。 That is, the gist configuration of the present invention is as follows.
1. In the blast furnace operation method of charging ore raw materials such as sintered ore, pellets, massive ore and blast furnace charging raw materials of coke into the blast furnace using a rotating chute,
When a mixed layer is formed in a predetermined region in the blast furnace by charging the mixed raw material and the coke into the blast furnace, the discharge rate of the mixed raw material into the blast furnace is 1.5 t. / S or more, The raw material charging method to the blast furnace characterized by the above-mentioned.
前記炉頂バンカーの1つまたは2つに、前記鉱石類原料若しくは前記鉱石類原料と前記コークスとを混合させた混合原料のいずれかまたは両者をそれぞれ貯留し、残りの炉頂バンカーの1つに前記コークスを貯留して、前記混合層を形成する際に、前記炉頂バンカーから同時に、前記コークスと前記鉱石類原料及び/又は混合原料を排出し、前記集合ホッパーで混合して前記旋回シュートに供給する
ことを特徴とする前記1に記載の高炉への原料装入方法。 2. At least two furnace top bunkers disposed at the top of the blast furnace, and a collecting hopper disposed at a discharge port of each furnace top bunker and mixing raw materials discharged from the furnace top bunker to supply the swirl chute With
One or two of the furnace top bunker stores either or both of the ore raw material or the mixed raw material obtained by mixing the ore raw material and the coke, and stores them in one of the remaining furnace top bunkers. When the coke is stored and the mixed layer is formed, the coke and the ore raw material and / or mixed raw material are discharged simultaneously from the furnace top bunker, mixed with the collecting hopper, and mixed into the swivel chute. 2. The raw material charging method to the blast furnace as described in 1 above, wherein the raw material is supplied.
図1に基づき、特許文献4に従って鉱石類原料及びコークスを高炉内に装入する具体的な装入要領を説明する。
なお、この例で、炉頂バンカー12bには鉱石類原料及びコークスの混合原料が、また炉頂バンカー12aにはコークスのみが、さらに炉頂バンカー12cには鉱石類原料のみが、それぞれ貯留されている。
ここに、炉頂バンカー12bに貯留される混合原料において、コークス量は全コークス量の30質量%以下に調整することが好ましい。というのは、混合されるコークス量が全コークス量の30質量%以下であれば、炉頂バンカー12bに貯留された時点で、コークスと鉱石類原料とで大きな偏析を生じることがなく、旋回シュート16によって形成される鉱石類原料とコークスとの混合層の混合率を略均一にすることができるからである。
これに対して、コークス量が全コークス量の30質量%を超えると、比重差及び粒子径差による偏析が起こりやすくなり、炉頂バンカー12bに貯留された時点でコークスと鉱石類原料との偏析が大きくなり、局所的に鉱石類原料のみやコークスのみが存在する領域が発生してしまう。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
A specific charging procedure for charging the ore material and coke into the blast furnace will be described with reference to FIG.
In this example, the ore raw material and coke mixed raw material are stored in the
Here, in the mixed raw material stored in the
On the other hand, when the amount of coke exceeds 30% by mass of the total amount of coke, segregation due to difference in specific gravity and particle size is likely to occur, and segregation between coke and ore raw material when stored in the furnace
ここで、旋回シュート16は、高炉10の軸心を中心に旋回すると同時に高炉10の軸心部から炉壁側へ向かって傾動するように逆傾動制御される、いわゆる逆傾動制御方式で原料装入を行う場合について説明する。
また、高炉の軸心部に中心コークス層を形成する場合について説明する。 In order to charge the raw material from the furnace bunker, the coke, mixed raw material and ore raw material discharged from the
Here, the
The case where the central coke layer is formed in the axial center portion of the blast furnace will be described.
このとき、旋回シュート16が略垂直状態に傾動している初期装入状態では、炉頂バンカー12b及び12cの流量調整ゲート13を閉じ、炉頂バンカー12aのみの流量調整ゲート13を開いて、この炉頂バンカー12aに貯留されているコークスのみを旋回シュート16に供給し、図1に示すように、軸心部に中心コークス層12dを形成する。 Now, the turning
At this time, in the initial charging state where the turning
なお、中心コークス層を形成する領域は、高炉軸心部を0、炉壁部を1とする高炉無次元半径において0以上、0.3以下とすることが望ましい。この理由は、コークスの一部を炉軸心部に集めることによって、軸心部での通気性ひいては高炉全体の通気性を効果的に改善することができるからである。
なお、中心コークス層を形成するために装入されるコークス量は、1チャージ当たりのコークス装入量の5~30質量%程度とするのが好ましい。というのは、軸心部へのコークス装入量が5質量%に満たないと軸心部周辺の通気性の改善が十分でなく、一方30質量%より多いコークスを軸心部に集中させた場合には、混合層に使用するためのコークス量が低下するだけでなく、軸心部をガスが流れすぎてやはり炉体からの抜熱量が増加するからである。好ましくは10~20質量%である。 Here, the coke amount of the
The region where the central coke layer is formed is preferably 0 or more and 0.3 or less in the dimensionless radius of the blast furnace where the blast furnace axial center part is 0 and the furnace wall part is 1. The reason for this is that by collecting a part of the coke in the core part of the furnace, the air permeability in the shaft part and thus the air permeability of the entire blast furnace can be effectively improved.
Note that the amount of coke charged to form the central coke layer is preferably about 5 to 30% by mass of the amount of coke charged per charge. This is because if the amount of coke charged to the shaft center portion is less than 5% by mass, the air permeability around the shaft center portion is not sufficiently improved, while more than 30% by mass of coke is concentrated on the shaft center portion. In this case, not only the amount of coke for use in the mixed layer is reduced, but also the amount of heat removed from the furnace body is increased due to excessive gas flow in the axial center. The content is preferably 10 to 20% by mass.
このように中心コークス層12d及び混合層12eで構成される層を順次積層することにより、高炉10内の軸心部では通気抵抗の小さい中心コークス層12dが高炉下部から高炉上部に向かって形成され、その周囲にコークスと鉱石類原料とが混合された混合層12eが形成されるのである。 Then, layers composed of the
By sequentially laminating the layers composed of the
この実験装置は、円筒状の炉体31の内周面に炉芯管32を配置し、この炉芯管32の外側に円筒状の加熱用ヒーター33を配置する。炉芯管32の内側には耐火物で構成された円筒体34の上端に黒鉛製るつぼ35を配置し、このるつぼ35内に装入原料36が装入されている。この装入原料36には、高炉下部の融着層と同程度の状態となるように、パンチ棒37を介して連結した荷重負荷装置38により上部から荷重を負荷する。円筒体34の下部には、滴下物サンプリング装置39が設けられている。 Therefore, in order to demonstrate the above-mentioned effect, the inventors investigated the change in the ventilation resistance by simulating the raw material reduction and the temperature raising process in the blast furnace using the experimental apparatus shown in FIG.
In this experimental apparatus, a
ここで、るつぼ35内に装入された装入原料36の鉱石としては50~100質量%の焼結鉱と、0~50質量%の塊鉄鉱石を混合したものを用いた。 The gas adjusted by the
Here, as the ore of the charging
図3に示したように、コークスを混合しない場合は圧損が最も高かったのに対し、コークスを添加することによって通気抵抗は著しく低下し、しかもこの効果はコークス量の増加に伴って大きくなることが分かる。この理由は、コークスを混合することによって鉱石の変形が抑制され、また混合コークス近傍の空隙が維持されるため、鉱石の変形により粒子間の空隙が減少して通気抵抗が上昇する現象が抑制されたものと考えられる。
また、同図に示したとおり、塊コークスと小中塊コークスとを用いた場合では、融着層における通気抵抗値が異なり、小中塊コークスを用いた場合には、塊コークスを用いた場合と比較して同じ混合量でも圧力損失が小さくなることが判明した。
ここに、塊コークスとは粒径が30~60mm程度のものを、また小中塊コークスとは粒径が10~30mm程度のものをいう。一方、鉱石類原料は、通常、粒径が5~25mm程度である。
ここに、鉱石類原料やコークスの粒径に起因した炉内通気性の悪化を回避するには、鉱石類原料の粒径は10~30mm、コークスの粒径は30~55mmとすることが好ましく、さらにこれらの粒径比(コークスの粒径/鉱石類原料の粒径)を1.0~5.5程度とすることが好適である。 FIG. 3 is a graph in which the relationship between the maximum pressure loss ratio and the mixing amount when the mixing amount of coke with respect to the ore is changed in the case where the size of the coke is different.
As shown in FIG. 3, the pressure loss was highest when coke was not mixed, whereas the addition of coke significantly reduced the airflow resistance, and this effect increased as the amount of coke increased. I understand. The reason for this is that mixing the coke suppresses the deformation of the ore and maintains the voids in the vicinity of the mixed coke, which suppresses the phenomenon in which the voids between the particles decrease due to the deformation of the ore and the ventilation resistance increases. It is thought that.
In addition, as shown in the figure, when using lump coke and small medium coke, the airflow resistance value in the fusion layer is different, and when using small coke, when using lump coke It was found that the pressure loss was small even with the same mixing amount.
Here, the lump coke means a particle having a particle size of about 30 to 60 mm, and the small and medium lump coke means a particle having a particle size of about 10 to 30 mm. On the other hand, ore raw materials usually have a particle size of about 5 to 25 mm.
Here, in order to avoid deterioration of the air permeability in the furnace due to the particle size of the ore raw material and coke, the particle size of the ore raw material is preferably 10 to 30 mm and the particle size of the coke is preferably 30 to 55 mm. Further, it is preferable that the particle size ratio (coke particle size / ore material particle size) is about 1.0 to 5.5.
本模型装置において、原料の落下軌跡および堆積挙動を実炉と一致させるために、原料粒径を実高炉の1/18倍に、原料装入量は1/18倍に、また装入シュートの旋回速度は1/18倍とした。 Therefore, the inventors conducted an evaluation test of the mixing ratio of coke in the ore raw material using a charging model device that becomes 1/18 scale of an actual blast furnace simulating the top of the blast furnace as shown in FIG. It was.
In this model device, in order to make the material's fall trajectory and deposition behavior coincide with the actual furnace, the raw material particle size is 1/18 times that of the actual blast furnace, the raw material charging amount is 1/18 times, and the charging chute is The turning speed was 1/18 times.
図4に示したとおり、バンカー内で鉱石とコークスを混合した場合は、排出の初期および後期で混合率が上昇し、排出中期では混合率は目標値(0.05)よりも減少している。これに対し、2つのバンカーから鉱石とコークスを同時に排出した場合は、鉱石中におけるコークスの混合率は目標値に対してほぼ一定の値を示した。従って、バンカー内混合よりも同時排出混合の方が、コークスの混合率を精度よく制御できることが分かる。 FIG. 4 shows the results of examining the change over time in the mixing ratio of coke in the charged raw material when ore and coke are mixed in a bunker or when ore and coke are discharged simultaneously from two bunker. In either case, the amount of ore and coke was constant, and the target mixing ratio was set to 0.05.
As shown in FIG. 4, when ore and coke are mixed in a bunker, the mixing rate increases in the early and late stages of discharge, and the mixing ratio decreases from the target value (0.05) in the middle of discharging. . On the other hand, when ore and coke were discharged from two bunkers at the same time, the mixing ratio of coke in the ore showed a substantially constant value with respect to the target value. Therefore, it can be seen that co-discharge mixing can control the mixing ratio of coke with higher accuracy than mixing in a bunker.
図5に示したとおり、排出速度が実機換算で0.85t/sのときと比較して、実機換算で1.27t/sのときの方がコークス混合率の最大値と最小値の差異が小さく、より均一に混合されていることが分かる。 Next, the results of investigating the change in the coke mixing ratio over the radial direction of the furnace when the discharge rate was changed to 0.85 t / s and 1.27 t / s (both converted to actual machine) under the simultaneous discharge conditions, As shown in FIG.
As shown in FIG. 5, the difference between the maximum value and the minimum value of the coke mixing ratio is greater when the discharge rate is 1.27 t / s in terms of actual equipment than when the discharge rate is 0.85 t / s in terms of actual equipment. It can be seen that it is smaller and more uniformly mixed.
図6に示したとおり、原料の排出速度が大きくなるに従って最大混合率と最小混合率との差は小さくなっている。すなわち、原料の排出速度が大きくすることによって、鉱石とコークスをより均一に混合できることが分かる。
特に、排出速度を1.5t/s以上とすることによって、最大混合率と最小混合率との差は大幅に低減し、1.8t/s以上でほぼ一定になっている。 Therefore, the inventors next investigated the change in the mixing ratio when the discharging speed at the time of simultaneous discharging was variously changed. The quality of the mixing rate was judged by the difference between the maximum mixing rate and the minimum mixing rate in the furnace radial direction. The obtained result is shown in FIG. In addition, it can be said that it is mixed more uniformly so that this difference is small.
As shown in FIG. 6, the difference between the maximum mixing rate and the minimum mixing rate decreases as the material discharge rate increases. That is, it can be seen that the ore and coke can be mixed more uniformly by increasing the discharge rate of the raw material.
In particular, by setting the discharge speed to 1.5 t / s or more, the difference between the maximum mixing rate and the minimum mixing rate is greatly reduced, and is substantially constant at 1.8 t / s or more.
装入原料の偏析は、装入原料流れが、静止した原料堆積面を流れる際に、小粒径である鉱石が原料堆積面の凹凸の影響を受け静止しやすいために生じると考えられる。
この点、装入速度が増加すると、堆積面移動時の装入原料がもつ移動エネルギーが増加し、小粒径である鉱石の静止が抑制される。また、原料の排出速度を大きくすると、装入原料流れの層厚が増加する。さらに、装入原料流れの層厚が増加すると、下面と接する粒子の比率は相対的に減少し、下面の凹凸の影響が低減する。
以上から、装入速度が増加すると、装入原料の偏析が抑制され、混合層の均一化が達成されるものと推察される。 Here, the reason why the difference between the maximum mixing ratio and the minimum mixing ratio is reduced by increasing the discharge rate of the charged raw material, that is, the uniformity of the mixed layer is not yet clearly clarified. However, the inventors speculate as follows.
The segregation of the charged raw material is considered to occur because ore having a small particle size is easily affected by the unevenness of the raw material deposition surface when the flow of the charged raw material flows on the stationary raw material deposition surface.
In this regard, when the charging speed is increased, the kinetic energy of the charging raw material during the movement of the deposition surface is increased, and the ore having a small particle size is suppressed. Further, when the discharge rate of the raw material is increased, the layer thickness of the charged raw material flow increases. Furthermore, when the layer thickness of the charged raw material flow is increased, the ratio of particles in contact with the lower surface is relatively decreased, and the influence of unevenness on the lower surface is reduced.
From the above, it is presumed that when the charging speed is increased, segregation of the charging raw material is suppressed and the uniformization of the mixed layer is achieved.
12a~12c 炉頂バンカー
12d 中心コークス層
12e 混合層
13 流量調整ゲート
14 集合ホッパー
15 ベルレス式装入装置
16 旋回シュート
31 円筒状の炉体
32 炉芯管
33 円筒状の加熱用ヒーター
34 円筒体
35 黒鉛製るつぼ
36 装入原料
37 パンチ棒
38 荷重負荷装置
40 混合装置
41 ガス分析装置
42 熱電対 DESCRIPTION OF
Claims (3)
- 焼結鉱、ペレット、塊状鉱石などの鉱石類原料及びコークスの高炉装入原料を、旋回シュートを用いて高炉内へ装入する高炉操業方法において、
前記鉱石類原料と前記コークスとを混合した混合原料として高炉内へ装入することにより、高炉内の所定領域に混合層を形成するに際し、前記混合原料の高炉内への排出速度を1.5t/s以上とすることを特徴とする高炉への原料装入方法。 In the blast furnace operation method of charging ore raw materials such as sintered ore, pellets, massive ore and blast furnace charging raw materials of coke into the blast furnace using a rotating chute,
When a mixed layer is formed in a predetermined region in the blast furnace by charging the mixed raw material and the coke into the blast furnace, the discharge rate of the mixed raw material into the blast furnace is 1.5 t. / S or more, The raw material charging method to the blast furnace characterized by the above-mentioned. - 前記高炉の炉頂に配設した少なくとも2つの炉頂バンカーと、各炉頂バンカーの排出口に配設され当該炉頂バンカーから排出される原料を混合して前記旋回シュートに供給する集合ホッパーとを備え、
前記炉頂バンカーの1つまたは2つに、前記鉱石類原料若しくは前記鉱石類原料と前記コークスとを混合させた混合原料のいずれかまたは両者をそれぞれ貯留し、残りの炉頂バンカーの1つに前記コークスを貯留して、前記混合層を形成する際に、前記炉頂バンカーから同時に、前記コークスと前記鉱石類原料及び/又は混合原料を排出し、前記集合ホッパーで混合して前記旋回シュートに供給する
ことを特徴とする請求項1に記載の高炉への原料装入方法。 At least two furnace top bunkers disposed at the top of the blast furnace, and a collecting hopper disposed at a discharge port of each furnace top bunker and mixing raw materials discharged from the furnace top bunker to supply the swirl chute With
One or two of the furnace top bunker stores either or both of the ore raw material or the mixed raw material obtained by mixing the ore raw material and the coke, and stores them in one of the remaining furnace top bunkers. When the coke is stored and the mixed layer is formed, the coke and the ore raw material and / or mixed raw material are discharged simultaneously from the furnace top bunker, mixed with the collecting hopper, and mixed into the swivel chute. The raw material charging method to the blast furnace according to claim 1, wherein the raw material is supplied. - 前記高炉装入原料を高炉内に装入するに際し、高炉の軸心部に中心コークス層を形成することを特徴とする請求項1または2に記載の高炉への原料装入方法。 3. The raw material charging method for a blast furnace according to claim 1 or 2, wherein a central coke layer is formed in an axial center portion of the blast furnace when the raw material charged in the blast furnace is charged into the blast furnace.
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