JPH06271908A - Method for charging raw material in multi-batches into bell-less blast furnace - Google Patents

Abstract

PURPOSE:To attain the improvement of the yield of coke by using small lump coke as the coke to be charged into a blast furnace. CONSTITUTION:After forming an ordinary coke layer in a preceding batch by using a turning chute 16 arranged at the lower part of a bell-less charging device having three furnace top bunkers 10 in parallel, a furnace core coke layer CO is formed at the center part of the furnace, and also, a small lump coke layer CN is formed at the furnace wall part. A bulky ore layer OL and a small lump ore layer OS are formed around the furnace core layer CO, and these five batches constitute one charge. A value of (CO/(CL+CO+CN))X100% is controlled to be in the range of 4-9wt.% so as to activate the center part of the furnace to obtain >=25(kg/t of molten iron) small lump coke charging quantity into the furnace wall part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a raw material multi-batch charging method for a bellless blast furnace for the purpose of using a large amount of small coke.

[0002]

2. Description of the Related Art Generally, in a bellless blast furnace, a swirling chute is used to alternately charge lump coke (hereinafter referred to as coke) and iron ore (hereinafter referred to as ore) such as sintered ore,
This forms a coke layer and an ore layer. As described above, the ores and coke charged alternately from the top of the blast furnace form a layered structure, gradually descending in the furnace, and the high-temperature CO generated by the reaction between the hot air blown from the tuyere and the coke.
After the ore is heated and reduced by the gas to form a softening cohesive zone, the droplets pass between the coke layers and the hot metal is stored at the bottom of the furnace.

In order to carry out such a blast furnace operation stably and efficiently, it is important to properly control the gas flow distribution rising in the furnace. In particular, an ore layer and a coke layer are alternately arranged in the furnace. When stacking the layers, a fixed amount of coke is intensively charged into the core to form a nearly continuous coke layer in the core, and the cohesive zone is reversed by centralizing the gas flow distribution in the blast furnace. It is known to maintain the V-shape and stabilize the furnace condition of the blast furnace.

For example, in Japanese Examined Patent Publication No. 64-9373, the charging of coke in each charge is divided into at least two series over time, and the total amount of coke charged in the charge is 92 to 98.5.
The weight% is charged so as to cover all the ore layer of the previous charge, and in the final charge series, 8 to the total amount of coke of the charge is charged.
By intensively charging 1.5% by weight into the center of the furnace,
The (Ore / Coke) ratio in the center of the furnace is
e) A method of depositing to be substantially smaller than the ratio is disclosed.

In this method, a fixed proportion of coke with respect to the total amount of coke is charged intensively in the center of the furnace, but it is premised that bulk coke is used as coke. That is, a large lump of coke produced in a normal coke oven is crushed by a crusher and adjusted to a particle size range suitable for use in a blast furnace, and these lump cokes are charged into a blast furnace to form a coke layer, and the charging is performed. The air permeability of the material layer is secured. Small coke that does not meet the particle size range was rarely used for blast furnaces.

However, since the lump coke used in the blast furnace requires a large amount of expensive coking coal, it has been attracting attention to use the small lump coke in the blast furnace in order to save the coking coal. For this reason, small coke is used for a blast furnace, and the following method has been proposed in order to effectively use the original ventilation function of coke and to improve the yield of coke production.

(1) When the coke and ore are charged in layers and the blast furnace is operated, ores and small coke (grain size 15
(less than 1 mm), and the mixed ore and coke having a normal particle size are charged in layers to operate the blast furnace (see Japanese Examined Patent Publication No. 52-43169). (2) Medium coke (grain size 15-
(30 mm) is limitedly charged so that it is retained in the furnace wall of the blast furnace (see Iron and Steel, 68 (1982), S698).

(3) In order to reduce the increase in pressure loss in the blast furnace due to the increased use of small grain raw material, the medium coke is separated,
Method of charging this with 1 / n charge (iron and steel, 70 (198
4), S777). (4) A method of mixing small batch coke (grain size 7 to 20 mm) with the first batch of ore and charging it into the blast furnace in order to eliminate defective ventilation in the lower part of the furnace (iron and steel, 70 (1984), S102. reference).

[0009]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention Prior Art (1)-
As in (1) and (4) of (4), when small coke or medium coke is mixed with ores and charged into a blast furnace, there is a problem that it stays in the hearth and impairs liquid permeability. is there. Further, as described in (3) above, there is a problem that even if the medium coke is separated from the normal coke and charged, if the charging position is not changed, the medium coke is likely to be deposited on the core and the air permeability is deteriorated. Furthermore, when the heat flow ratio around the furnace wall is controlled by medium coke as described in (2) above, the medium coke is 40 (kg / t).
・ When the temperature is higher than that of hot metal, the central part of the furnace is deactivated,
Central charging of coke is essential.

The present invention has been made in consideration of the above-mentioned circumstances, and is a bellless blast furnace capable of ensuring the air permeability and liquid permeability of the central portion of the furnace and increasing the amount of small coke used. It is an object of the present invention to provide a raw material multi-batch charging method.

[0011]

[Means for Solving the Problems] To achieve the above object
The present invention relates to a bell having three top bunkers in parallel.
Using a swiveling chute installed under the less charging device
The normal batch coke from the front wall to the center of the furnace.
Layer (C_L), The normal coke layer (C _L)Up
In addition, a coke was separately charged into the center of the furnace using a turning chute.
Then the core coke layer (C_O) Of the bellless blast furnace forming
In the raw material multi-batch charging method, the normal coke layer is used.
(C_L) Separately and separately charged small coke into the furnace wall
The small coke layer (C_N) Form and pull
The above-mentioned central coke layer (C_O) A swirling chute around
When ore is charged by using to form an ore layer,
Core coke layer (C_O) Form the weight of the coke charge
Amount ratio is the total amount of coke charged per charge (C_L+
C_O+ C_N) Of 4 to 9%.
This is a multi-batch raw material charging method for the Lures blast furnace.

In the above-mentioned method of the present invention, it is preferable to change the amount of coke charged to form the core coke layer (C _O ) according to the furnace bottom temperature and / or the heat flux. The small lump coke charging amount to form small lump coke layer (C _N) in the furnace wall portion may be 25 (kg / t · pig iron) or more.

[0013]

In the present invention, the amount of coke forming the core coke layer (C _O ) is determined by the total amount of coke (C _L + C _O + C).
_By keeping the _N content in the range of 4 to 9%, the (ore / coke) ratio = O / C in the central part of the furnace is kept low, and its air permeability is kept good. If it is less than 4%, there is no control effect of lowering the O / C, and if it exceeds 9%, there is a risk of excessive ventilation in the center of the furnace, raising the temperature of the bottom of the furnace, and melting the bottom brick.
Thus more than 4%, and it is essential to keep the range of 9% or less, thereby usually coke layer (C _L) small lump coke separately and independently charged small lump coke layer on the furnace wall portion of the Enables operation of the blast furnace forming (C _N ).

The structure and operation of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a bellless charging device having three bunker 10 in parallel on the furnace top of the blast furnace of the present invention and the furnace bottom. As shown in the figure, when charging the coke and ore to the bellless blast furnace 14, charging 1 charge to 5
It is divided into batches and charged into the furnace.

That is, after the normal batch coke (lump coke having a normal grain size) was charged from the furnace wall to the center of the furnace to form a normal coke layer ( _CL ), a swirling chute 16 was used. together with BetsuSoIri normal coke furnace center portion to form a core coke layer (C _O), by charging normally coke layer nodules coke oven wall portion (C _L) separately and independently Form a small coke layer (C _N ). The center coke layer (C
Surrounding _O) and mass ore (O _L) nodules ore (O _S) with charging and 5 batches to cover all coke layer (C) is intended to be first charge.

The procedure for charging the multi-batch raw material into the furnace by the swirling chute 16 of the present invention will be described. As shown in FIG. 1, the coke C in the top bunker 10 is swirled before charging the blast furnace 14. The chute 16 is driven by a tilt motor 31 controlled by a tilt position control device 30, and a tilt angle detector 32 is provided.
Depending on the specified position, for example, the tilt angle θ = 53 at the standby position
Turn chute 16 so that tilt angle θ = 52 ° from °
The tip of is tilted to the start start position close to the furnace wall 2 side, and the tilting is once stopped.

Next, the turning control device 33 drives the turning electric motor 34 to start turning the turning chute 16 at a predetermined angular velocity ω = 7.9 rpm, and the flow control gate controller 36 commands the flow control gate 12 to be controlled. Open the opening, bunker on the top of the furnace
Coke C stored in 10 is introduced through a collecting hopper 22 onto a swirling chute 16 installed in the blast furnace 14, and dumped from the tip of the swirling chute 16 to start charging coke into the furnace. To be done.

At this time, the rotation is controlled by a command from the turning control device 33.
It controls the turning of the turn chute 16 and the tilt position control device.
The tilt angle θ of the turning chute 16 is set by the command from the unit 30.
The range from 52 ° to 26 ° gradually increases from the furnace wall 2 side to the inside of the furnace
The inside of the furnace follows the specified dump pattern while changing to
To turn. In this way the normal coke layer
(C _L) The coke required to form
It is installed in the furnace from the tip of the swirling chute 12 so that it becomes layered.
Let in.

In the upper surface by charging the coke as described above
Ore layer of the previous charge with a hollow center (O _L), (O_S)upon
Coke layer (C_L) Is formed. This cork
Layer (C_L) Is coke from the furnace wall 2 side toward the center of the furnace
Since the gas gradually flows in, the layer thickness in the radial direction of the furnace cross section is almost constant.
It is uniformly formed. Installation of coke C in the rooftop bunker 10
When the flow is completed, the flow rate is adjusted by the command of the flow rate adjustment gate device 36.
Close the adjusting gate 12 and return the turning chute 16 to the standby position.
Immediately and continuously according to the command from the tilt position controller 30.
Centering around the turning chute 16 by a tilting motor 31 controlled by
The charging position, that is, the tilt angle θ becomes 15 degrees or less.
Is tilted. At this time, the tilt angle detector 32
When the fixed position is detected, the tilt position control device 30 tilts the stop command.
The tilt is stopped by applying it to the dynamic motor 31.

Next, the turning electric motor 34 is driven by a command from the turning control device 33 to move the turning chute 16 at a predetermined angular velocity ω = 10.5rp.
Coke drops from the top bunker 10 as the flow adjustment gate 12 is opened to a predetermined opening according to a command from the flow rate adjustment gate control device 36 of the top bunker 10 containing the lump coke C _O while starting the turning at m. And the funnel-shaped collecting hopper 22
The core coke layer, which is guided to the swirl chute 16 via the slab and is locally accumulated in the central part of the reactor by being guided by the swirling chute 16 that is vertically swirling and raised on the coke layer ( _CL ). (C _O ) is formed. The turning direction of the turning chute 16 may be either forward or reverse.

When the core coke layer (C _O ) is formed in this way, the swirling chute 16 is raised to set the inclination angle θ = 52 ° and the tip of the swirling chute 16 is returned to the side closer to the furnace wall portion, so that the swirling chute 16 has a predetermined angular velocity. omega = starts the pivot 7.9Rpm, set a small lump coke C _N a flow rate control gate 12 is opened a predetermined opening by a command flow rate control gate control device 36 of the furnace top bunker 10 containing the small lump coke C _N Introduced onto the turning chute 16 in the blast furnace 14 via the hopper 22, and
Forming small lump coke layer (C _N) 16 the tip of the furnace wall portion by dumping.

[0022] In the normal state of forming a small lump coke layer (C _N) on the center portion to the furnace wall portion while forming the core coke layer (C _O) of the coke layer (C _L), in the furnace top bunker 10 acceptance mass ore (O _L) and nodules ore (O _S) sequentially charged with 2 batches one layer ore layer (O _L), to form a (O _S). Such a raw material charging step is sequentially repeated,
Core coke layer on the furnace central part (C _O) is columnar coke area by stacking formed small lump coke layer furnace wall portion with air permeability is ensured (C _N) and nodules ore layer (O _N) With this, the air permeability on the furnace wall side is appropriately suppressed. In some cases, two batches of one ore layer ( _OL ), (O _L )
Ore layer ( _OL ) in one batch instead of forming _S )
It is also possible to use only 4 batches and 1 charge.

After the two ore batches of ore layers (O _L ) and (O _S ) are formed as described above, the tilting motor 31 is stopped by the command of the turning control device 33, and then the tilting position control device is used.
The tilting motor 31 is driven by the command of 30 and the swing chute 16
Tilt toward the standby position. When the tilt angle detector 32 detects that the tilt angle θ = 53 ° has been returned to the standby position, the tilt motor 31 is instructed by the tilt position controller 30.
To stop the turning chute 16 and finish charging 5 batches and 1 charge. The furnace top sequence controller 37 is
It controls a series of controls including the tilt position control device 33 and the flow rate control device 36 described above.

In the present invention, the core coke layer (C_O)
The weight ratio of the charging amount of the lump coke that forms the
Total charged coke amount (C + C_O+ C_N) 4-9 layers
It is important to adjust the volume% range, and
The weight ratio of the coke charged was buried in the center of the furnace bottom 8.
Temperatures measured by thermometers 6a and 6b, respectively
T ₁, T_OTemperature difference ΔT = T₁-T₀Or the transmission of the hearth 8
Determined based on the heat flux to the hearth obtained by thermal calculation,
This activates the charge in the bottom of the furnace and
Lump coke layer (C_N) Form the small coke charge
It is possible to make 25kg or more per ton of hot metal.
is there.

[0025]

EXAMPLES Examples of the present invention will be described below. In a bellless blast furnace with an internal volume of 4500 m ^3, the tap ratio was 2.0 t /
As shown in FIG. 1, the swirl chute 16 provided at the bottom of the bellless charging device having three furnace top bunkers under the condition of coke ratio of 500 kg / t at dm ³ is operated by the above-mentioned procedure. while switching the charging of usually coke, usually to form coke layer (C _L) by entering 27.5T / charge instrumentation swirling chute to pivot 12 times. In the concentrated coke charging into the central part of the furnace, the swirling chute was tilted at an angle of θ = 12 degrees to 2
Turned twice and charged 2.5t / charge and charged core coke layer (C
_O ) form.

When charging small coke (grain size 20 to 6 mm), the swirling chute was swung three times toward the furnace wall at an inclination angle θ = 52 degrees, 3.0 t / charge was charged, and the small coke layer (C
_N ) are formed. Furthermore, in the charging of lump ore O _L , in order to form two batches of one ore layer O _L and O _S respectively, the orbiting chute is turned 10 times to charge lump ore 75 t / charge,
Subsequently, the charge of charging one charge was carried out in five batches into the blast furnace on the schedule of turning the swirling chute four times to charge 35 tons of small ore.

In this case, the core coke layer (C _O )
The amount of lump coke that forms the coal is 2.5t per charge
, And the coke SoSoIriryou _{(C + C O + C N} ) = 27.5 +
Since 2.5 + 3.0 = 33.0t, the weight ratio of coke charged centrally in the core is (C _O / C + C _O + C _N ) × 100 =
2.5 / 33.0 = 7.5%, and the small coke usage ratio is 6
It was 0 kg / t.hot metal.

[0028] The hitting the formation of the core coke layer (C _O) according to the coke concentration charging to such furnace center portion, the blast furnace
On buried in the furnace bottom 8 of 14, measures the temperature T _1, T _O, respectively, by a thermometer 6a, 6b of the lower, the temperature difference [Delta] T =
T ₁ -T _O is adjusted in the range 4 to 9% of coke by weight to the furnace center portion to be between about 45 to 55 ° C.. This is because if the temperature difference ΔT is less than 45 °, the furnace bottom temperature T ₁ tends to decrease. In such a case, the weight ratio (C _O / _CL + C _O
Increase + C _N ) × 100 to increase the bottom temperature. On the other hand, if the temperature difference ΔT exceeds 55 ° C, the bottom temperature T ₁ tends to rise too much. Therefore, the weight ratio of coke concentrated charging to the center of the furnace at the present time should be changed to the smaller side. It suppresses an excessive rise.

FIG. 2 shows the charging amount (kg / t.molten pig iron) of the small coke C _{N in} the furnace wall and the charging amount (t / charge) of (normal coke C _L ) + (core coke C _O ). It shows the daily transition of the furnace bottom temperature difference ΔT = (T ₁ −T ₂ ) when V is changed. Although not shown charging amount of lump ore (O _L) and a small lump coke O _S in FIG. 2, the in the usual coke C _L only blast furnace operation to 32t / charge charged initially as shown in FIG. 2 Since the small coke C _N was used for the first few days, the small coke C _L was charged into the furnace wall while keeping the same amount of the small coke C _L.
The operation of gradually increasing _N (kg / t · hot metal) was carried out until the number of days reached close to 20 days. In this case, the small coke charging amount reached the level of 48 (kg / t · hot metal).

The effect of changing the charging amount of the coke amount usually takes 2-3 weeks, so the state of the temperature difference ΔT at the bottom of the furnace was observed, and the charging of the small coke C _N to the furnace wall was observed. The temperature difference ΔT gradually decreases, probably due to the effect of suppressing the gas peripheral flow due to the gradual increase of the input amount, and the temperature difference ΔT becomes 40 ° C or less after the number of days exceeds 20 days The cooling tendency of the part was shown.

Since the temperature difference ΔT continued to decrease thereafter, in order to recover the temperature of the bottom of the furnace without reducing the amount of the small coke C _N used, the core coke C _{O was} begun when the number of days reached 40 days. Was gradually increased, and the normal coke C _L was reduced by the increased amount. As a result, the temperature difference ΔT increased and the furnace bottom temperature recovered after the number of days approached 60 days. After that, the temperature difference ΔT became 50 ° C or more, so the charging amount of the core coke C _O ( When the value of (t / charge) was decreased, the temperature difference ΔT again fell below 40 ° C. Therefore, the core coke charging amount (t / charge) was increased to recover the temperature difference ΔT to the 50 ° C level. In this case, the core coke C _O charging amount adjustment range is approximately 1.5 to
It is 3.0 (t / charge), and even if the charging amount of small lump coke C _N is increased to 50 (kg / t / hot metal), the furnace bottom temperature difference ΔT
Could be in the preferred range of 45-55 ° C.

When the weight ratio of the core coke C _O charged is changed based on the heat flux calculated by heat transfer calculation to the hearth bottom of the furnace, the heat flux to the hearth bottom is 2000 kcal / m ^2.
・ Core coke C per charge to be more than h
_The weight ratio of _O charged is the total amount of coke charged (C _L + C _O + C
_N ) in the 4-9% range. The heat flux to the furnace bottom is set to 2000 kcal / m ² · h or more because the heat delay is less than 2000 kcal / m ² · h as shown in FIG. In addition, the roughing time becomes long, and not only the tapping time becomes long but also the tapping becomes extremely unstable. In contrast, the heat flux to the bottom of the furnace is 2000 kcal / m
^This is because when the time is ² · h or more, the slow delay time and the rough discharge time are drastically shortened, and stable tapping from the blast furnace can be achieved.

The raw material charging method for the bellless blast furnace of the present invention is shown in Table 1 in comparison with the result of the conventional method in which 1.5 to 8% / total amount of coke is concentratedly charged in the center of the furnace.

[0034]

[Table 1]

As shown in Table 1, according to the present invention, not only the amount of small coke used can be significantly increased as compared with the conventional method, but also the core heat flux can be improved, and the slow delay time is increased. Can be shortened.

[0036]

As described above, according to the present invention, the core coke layer can maintain good air permeability in the center of the furnace, and can increase the amount of small coke used to improve the coke yield. Is achieved. Further, the temperature of the bottom of the furnace and the heat flux of the core can be maintained satisfactorily, whereby the charge in the center of the furnace is activated and stable blast furnace operation becomes possible.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a furnace top charging device and a furnace bottom of a bellless blast furnace of the present invention.

FIG. 2 shows daily changes in small coke C _N (kg / t · hot metal), normal coke (C _L ) + core coke (C _O ) charge (t / charge) and bottom temperature difference ΔT. It is a diagram.

FIG. 3 is a diagram showing a relationship between core heat flux and filtration delay time.

FIG. 4 is a diagram showing a relationship between core heat flux and roughening time.

[Explanation of symbols]

 6 Thermometer 8 Furnace bottom 10 Top bunker 12 Flow rate control gate 14 Blast furnace 16 Swing chute 22 Collecting hopper 30 Tilt position control device 31 Tilt motor 32 Tilt angle detector 33 Swing position control device 34 Swing motor 35 Swing angle detector 36 Flow rate Adjustment gate controller 37 Furnace top sequence controller

Claims (3)

[Claims] 1. A bed having three roof top bunker in parallel.
Using a swivel chute installed under the Lures charging device
The normal batch coke from the front wall to the center of the furnace.
Layer (C_L), The normal coke layer (C_L)Up
In addition, a coke was separately charged into the center of the furnace using a turning chute.
Then the core coke layer (C_O) Of the bellless blast furnace forming
In the raw material multi-batch charging method, the normal coke layer is used.
(C_L) Separately and separately charged small coke into the furnace wall
The small coke layer (C_N) Form and pull
The above-mentioned central coke layer (C_O) A swirling chute around
When ore is charged by using to form an ore layer,
Core coke layer (C_O) Form the weight of the coke charge
Amount ratio is the total amount of coke charged per charge (C _L+
C_O+ C_N) Of 4 to 9%.
Lures blast furnace raw material multi-batch charging method. 2. The raw material multi-batch apparatus for a bellless blast furnace according to claim 1, wherein the amount of coke charged to form the core coke layer (C _O ) is changed according to the bottom temperature and / or the heat flux. How to enter. 3. A furnace wall portion in a small lump coke layer (C _N) bell-less blast furnace according to claim 1, characterized in that a small lump coke charging amount 25 (kg / t · pig iron) or more to form a Raw material multi-batch charging method.