JPH0733528B2 - Blast furnace operation method - Google Patents

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention charges raw material cost and fuel ratio by charging an inexpensive porous lump iron ore containing a large amount of water of crystallization and adhered powder ores and having a lot of vein ore components into a blast furnace in a lump state. The present invention relates to a method of operating a blast furnace for reducing the amount of electricity.

[0002]

2. Description of the Related Art A blast furnace is operated by charging an iron source such as sinter, iron ore and pellets, and coke, and it has a relatively good reducing property as an iron ore and has a thermal cracking property. Usually, about 5 to 20% of Hamassley ore, Newman ore, etc., which are good iron ore, are used. Also,
Heat cracking ores such as MBR ores, or ores with low heat cracking properties, but with a lot of porous water of crystallization and adhering powder ores (3 mm or less), and low cost lobe river and gore with high vein ore components Porous massive iron ore such as ore has a large amount of pulverization in the shaft part of the blast furnace, and it is feared that it will not be possible to maintain stable operation due to poor ventilation, and this kind of ore is directly charged into the blast furnace. Nothing was done, but it was crushed and used as a sintering raw material. However, in recent years, JP-A-1
As disclosed in Japanese Patent Laid-Open No. 219111, a method has been proposed in which a heat crackable ore is charged in the furnace wall side part and the excellent iron ore is charged in the furnace center part.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
If instead of the heat cracking ore proposed in Japanese Patent No. 111, the porous massive iron ore that has been used as a sintering raw material as described above is charged as it is, even if it is on the side of the blast furnace wall. Even if it can be used, it is less than about 1% of the total iron source charged even if it can be used, and stable operation of the blast furnace becomes impossible. It was a thing. In addition, the charge to be charged in the central part and the charge to be charged in the side of the furnace wall must be separately provided, which is complicated. In order to reduce the raw material cost and the fuel ratio without the above problems, the present invention maintains a stable blast furnace operation even if a large amount of the above-mentioned porous lump iron ore is charged, and at any position in the furnace. The challenge is to make it possible.

[0004]

The present invention has been made to solve the above problems, and is characterized by the first feature thereof.
The means of using a porous lump iron ore having a porosity of 30% or more and a crystallization water of 3% or more as the iron ore to be charged into the blast furnace, the porous lump iron ore having a diameter of 3 mm or less of 1% or less, Sinter ore is charged into the blast furnaces such that they are mixed at least in the blast furnaces. Further, the second means is the first means according to the reduction pulverization index of the sinter and the residence time of the charge in the low temperature reduction zone of the furnace temperature of the blast furnace shaft portion of 500 to 700 ° C. It adjusts the amount of lump iron ore used.

As a method for removing the powdered ore of 3 mm or less to 1% or less, a method of sieving the porous lump iron ore with a vibrating sieving device, and then sprinkling water from above the lump iron ore, and a water tank There are a method of immersing inside, a method of preheating with an exhaust gas from a hot air oven or a coke oven, and applying vibration to perform sieving. Further, it is sufficient that the porous lump iron ore and the sinter are capable of forming a mixed layer at least in the blast furnaces, and as a method thereof, the porous lump iron ore and the sinter are mixed in advance before charging into the blast furnace. However, it is not particularly limited as long as it can be mixed during charging (on the bell, on the charging belt). The residence time of the charge in the low-temperature reduction zone is determined by the correlation with the absolute value of the furnace top hydrogen gas utilization rate, or by the temperature distribution in the furnace in the vertical direction obtained by the sonde apparatus. is there.

[0006]

[Function] The present inventors charge raw material costs by charging inexpensive lobed rivers, gore ores, and other porous and highly crystallized water and highly reducible lump iron ore into the blast furnace in the lump state. Various experiments and studies were conducted on the method of reducing the noise.
In this porous lump iron ore, (1) powdered ore with a particle size of 3 mm or less adheres to the surface, and this adhered powdered ore cannot be removed simply by sieving with a vibrating screen device, and the ratio of the powdered ore is It is as high as 7%. (2) Since it contains 3% or more of water of crystallization, it is easily pulverized when the water of crystallization comes off, and its strength is weak. (3) It is easy to reduce powder. (4) It has properties such as shrinkage and particle size reduction at high temperatures.

For this reason, if the blast furnace is charged as it is, clogging occurs in the shaft portion of the blast furnace due to the above properties, and the air permeability in the furnace deteriorates. As a result, the start of softening and fusing shifts to the upper part of the blast furnace (the upper surface of the fusing zone rises), causing a decrease in the indirect reduction rate of ores and increasing the FeO content of the slag melt dripping to the bottom of the furnace. Since the endothermic reaction amount of No. 1 is increased, the core temperature is lowered, the amount of slag is increased, and further, due to the enlargement of the cohesive zone, the air permeability of the lower part of the blast furnace is deteriorated and it becomes difficult to maintain stable operation. It was not possible to take advantage of the high porosity of the porous lump iron ore, and the fuel ratio had to be increased.

[Chemical 1]

Therefore, the present inventors first investigated and examined the relationship between the powdered ore of the porous lump iron ore and the air permeability in the furnace. As shown in FIG. 2, a charging device 3 is provided in an upper portion of a container 2 lined with a refractory material 1, and a cutting device 4 for continuously discharging a charged lump iron ore is provided in the lower portion thereof. 4, a hot-air pipe 5 for supplying hot air of 1000 ° C. is connected around the upper part of the No. 4 and an exhaust duct 6 is provided on the upper part of the test device to create a thermal condition equivalent to that of the shaft part of the blast furnace. The relationship between the ratio of the powdered ore having a grain size of 3 mm or less charged together with the porous massive iron ore from the device 3 and the pressure loss in the container 2 was investigated.

As a result, as shown in FIG. 1, it was found that the pressure loss in the container 2 drastically decreases when the ratio of the powdered ore becomes 1% or less. This is because the higher the ratio, the more the ore layer in the container 2 is clogged with the ore powder, and the accumulating portion of the ore powder in the container 2 is caused by the upward circulation of the ore powder. Breathability deteriorates. And due to the deterioration of air permeability, a nonuniform flow is generated in the high temperature rising gas, and the porous lump iron ore in this nonuniform flow portion is rapidly heated, so that the crystal water is rapidly vaporized,
It is also presumed that the above-mentioned increase in pressure loss is promoted by accelerating the breakage and pulverization phenomenon caused by the increase in the ore internal pressure and accelerating the ventilation failure.

On the contrary, when the ratio of the powdered ore is 1% or less, the ore layer is less likely to be clogged with the powdered ore, the air permeability in the container 2 is not deteriorated, and the gas flow in the container 2 is reduced. Stabilizes and becomes a piston flow. For this reason, the porous lump iron ore charged in the container 2 is gradually heated as it descends in the container 2, and as a result, vaporization of crystal water gradually occurs, and the amount of crushed powder of the porous lump iron ore is reduced. It is assumed that the air permeability will decrease and the breathability will not deteriorate. Further, in the case where the porous massive iron ore is mixed with the sintered ore and charged into the container 2 to form a layer, as compared with the case where they are separately charged without mixing and different layers are formed. It was found that the breathability was improved by about 50%.

It is considered that this is because the porous lump iron ore contracts in a high temperature region to reduce the particle size. That is, when a single layer of only the porous lump iron ore is formed, when the particle size of the porous lump iron ore shrinks, the layer thickness of the lower layer portion becomes thin due to the load from the upper layer portion and the packing density becomes When the mixed layer of porous lump iron ore and sintered ore is formed as in the present invention, the air permeability is deteriorated due to the rise and the porosity in the layer is decreased. Even if the particle size of the lump iron ore shrinks, the sintered ore hardly shrinks in this temperature range, so it is assumed that the layer thickness hardly changes and the air permeability does not deteriorate.

From this result, after sieving by the vibrating sieving apparatus as described above, water was sprinkled from above the lump iron ore and sieving was performed to give a ratio of powdered ore of 3 mm or less (attached to the surface of the porous lump iron ore. Porous lump iron ore containing less than 1%) was charged into the blast furnace together with sinter as part of the iron source charged into the blast furnace, and the air permeability in the furnace during this time was measured. However, stable blast furnace operation was possible without deterioration of air permeability. Also, paying attention to the porosity of the porous lump iron ore, the relationship between the porosity and the particle size and the heating / reduction reaction efficiency is actually fair 1-2.
No. 7038 gazette proposed reaction simulator in a blast furnace (a furnace core tube in which a porous lump iron ore is filled from the upper part and a reducing gas is conducted from the lower part, and the reducing gas and the porous lump iron ore are countercurrently contacted, A device having a heater surrounding a part of the core tube and movably provided in the reducing gas downstream direction) was used for the investigation.

As a result, as shown in FIG. 3, the smaller the iron ore particle size, the better the heating / reduction reaction efficiency.
In particular, if the ore having a porosity of 30% or more is sized to a grain size of 25 mm or less, a heating / reduction reaction efficiency equal to or higher than that of the sintered ore can be obtained. However, when the particle size is 3 mm or less, the heating / reduction reaction efficiency is good, but as described above, it may promote the decrease (clogging) of the porosity of the charging layer, which hinders stable operation of the blast furnace. . Further, it has been found that the heating / reduction reaction efficiency improves as the porosity increases. That is, if the porous massive iron ore having a porosity of 30% or more has a grain size of 3 mm or more, it is possible to operate the blast furnace with fuel equal to or less than that of the sintered ore, and
It was found that the reduction reaction efficiency can be significantly improved and the fuel ratio can be reduced compared to the conventionally used good iron ore (porosity 25% or less).

Further, the sinter ore or iron ore charged into the blast furnace is pulverized mainly during the reduction, and this reduction pulverization takes place at a furnace temperature of 500.
It is most prominent in the low temperature reduction region from to 700 ° C. In order to investigate the residence (falling) time of sinter or iron ore and the pulverization rate of 3 mm or less in this low temperature reduction region, an experiment was conducted using the same blast furnace reaction simulator as described above. The result is shown in FIG. As shown in FIG. 4, it was found that the pulverization rate increases as the reduction powdering index (RDI) value of the sinter increases, and further increases as the residence time increases.

Further, the reduction pulverization of the porous lump iron ore showed a substantially constant high pulverization rate during the residence time of 20 to 90 minutes regardless of the residence time. Further, it has been found that the good iron ore used conventionally is promoted to be pulverized when the residence time is about 80 minutes, and it is difficult to be pulverized at other times. In the actual blast furnace, the charge is 500 to 700
The time to fall (stay) in the low temperature reduction region of C is usually about 30 minutes. However, when the Ore / Coke locally becomes high, the low temperature part spreads and it may take about 2 hours at the longest. is there.

[0016] Thus, by adjusting the amount of the porous lump iron ore charged in accordance with the residence time of the charge in the low temperature reduction region and the reduction powdering index of the sinter, the low temperature in the blast furnace can be controlled. It has been found that it is possible to reduce the amount of reduced pulverization generated in the reduction region and maintain it at or below the upper limit powder ratio (a powder ratio of about 30% of 3 mm or less, which varies depending on the blast furnace) required for stable operation. That is, if the residence time of the charge in the low-temperature reduction region is about 30 minutes as described above, the fine iron ore used conventionally is less reduced and pulverized, and the sinter is also less pulverized. Therefore, a large amount of porous lump iron ore can be charged.

Further, when the low-temperature reduction zone is long and the residence time of the charge in this zone is long and exceeds 80 minutes, the reduction pulverization of the above-mentioned fine ore increases and the sinter ore pulverization also sequentially increases. Therefore, the amount of porous lump iron ore charged is reduced. Furthermore, in any case, if the reduction or pulverization index of the sinter to be charged is low, the reduction or pulverization of the sinter ore is small, so that a larger amount of porous lump iron ore can be used. is there. Upper limit ratio O of this porous lump iron ore
T is LD × (δL0 + δL) + 0S × (δS0 + δS) + 0T × (δT0 + δT) =
It can be calculated by 30-α.

However, LD: proportion of sinter used, 0S: proportion of good iron ore, δL: RDI of sinter, and pulverization rate of sinter determined by residence time of sinter in the low-temperature reduction zone in the furnace. (Percent), δS: Fine iron ore pulverization rate (percentage) determined by the residence time of excellent iron ore in the low-temperature reduction region in the furnace, δT: Porous lump determined by residence time of the iron ore in low-temperature reduction region in the furnace Iron ore pulverization rate (percentage), δL0: Sintered ore carry-in powder rate, δS0: Excellent iron ore carry-in powder rate, δT0: Porous lump iron ore carry-in powder rate, α: Furnace interior It is the ratio of powdering upon entering.

[0019]

EXAMPLES Examples of the present invention will be described below together with comparative examples. This example has an internal volume of 4000 cubic meters and
Coke 4.25, tuyere front frame temperature 2276 ° C (blast temperature: 1250 ° C, blast moisture: 20 g / N cubic meter, pulverized coal blowing rate: 90 kg / t-pi
After sieving the porous lump iron ore and the fine iron ore into the state shown in Table 1 in a blast furnace operating in g) with a vibrating sieving device, the porous lump iron ore was sprinkled to remove the porous lump iron ore The fine ore having a size of 3 mm or less attached to the surface was removed, and the good iron ore was directly charged into the blast furnace. The situation is shown in Table 2 together with the conventional example (using the good iron ore) and the comparative example. As can be seen from Table 2, in Examples 1 to 5 of the present invention, the fuel ratio was able to be reduced and the furnace conditions were good as compared with the conventional example (charged with excellent iron ore only). Example 1 is a case where a porous lump iron ore (gore iron ore) is used instead of a part of the excellent iron ore of the conventional example.

Since Example 2 has a longer residence time of the charge in the low temperature reduction region than Example 1, Example 1
Under the conditions of charging iron source, the powder ratio in the furnace increased significantly (1
9% to 30.3%: the value calculated by the above formula) and exceeds the upper limit pulverization rate required for stable operation of the blast furnace. For this reason, the sinter having a low RDI is switched to, and the ratio of the porous lump iron ore (lobe river iron ore) used is decreased, the ratio of the fine iron ore used is increased, and the pulverization rate is set to about 25%. It prevented the situation from worsening. In Example 3, since a sinter having a lower RDI than that in Example 1 was used, the powder ratio was lower (19 to 18%) under the charged iron source conditions of Example 1 as compared with Example 1, and thus was excellent. This is a case where all of the iron ore is changed to a porous lump iron ore (gore iron ore) to make the powder ratio to the same level.

Example 4 is a case where the residence time of the charge in the low temperature reduction region is longer than that in Example 3, and in this case as well, in the charged iron source condition of Example 3, in the furnace. Since the powder ratio greatly increases and the powder ratio becomes 30% or more, the ratio of the porous lump iron ore (gore iron ore) is decreased and the usage ratio of the porous lump iron ore (gore iron ore) is reduced, and the excellent ratio is obtained. Iron ore was used, and the powder ratio was set to about 27%. Example 5 is a case where a porous lump iron ore (gore iron ore) is used instead of the pellet.

In Comparative Example 1, the ratio of the powdered ore adhering to the porous lump iron ore (lobe river iron ore) was as high as 3%. In this case, clogging occurred and the furnace condition deteriorated, The fuel ratio has also reached a high level. Furthermore, in Comparative Example 2, the particle size of the porous lump iron ore (gore ore) is from 15 mm to 30 mm.
In this case, the furnace condition is good, and the fuel ratio can be reduced as compared with the conventional example, but the heating / reduction reaction efficiency is lower than in Examples 1 to 5, and the fuel ratio is reduced. The ratio is slightly higher.

[0023]

[Effect] As described above, according to the present invention, an inexpensive porous massive iron ore that is porous and has a large amount of crystal water and surface-adhered powdered ore and a large amount of vein ore component can be obtained without crushing it into a sintered ore. A large amount of blast furnace can be charged into the blast furnace and used.
Raw material costs can be reduced. In addition, by utilizing the characteristics of being porous, we aim to improve heating and reduction efficiency,
The fuel ratio can be reduced. Furthermore, RD of sintered ore
I, it is possible to maintain stable blast furnace operation by adjusting the amount of the above-mentioned porous lump iron ore used in accordance with the residence time in the low-temperature reduction region of the charge and controlling it appropriately. Therefore, the effect in this field is enormous.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the ratio of the powdered ore of 3 mm or less attached to the surface of the porous lump iron ore and the pressure loss in the charge.

FIG. 2 is a side sectional view of a test apparatus for investigating the ratio of fine ore and pressure loss

FIG. 3 is a diagram showing the relationship between the particle size of porous lump iron ore and the efficiency of heating / reduction reaction.

FIG. 4 is a diagram showing the relationship between the residence time in the low temperature range and the pulverization rate of the blast furnace charge.

[Table 1]

[Table 2]

Claims (2)

[Claims] 1. A porosity of 3 as an iron ore charged into a blast furnace.
When using a porous lump iron ore having 0% or more and 3% or more of water of crystallization, the porous lump iron ore having a diameter of 3 mm or less and 1% or less is mixed with at least a blast furnace. A method of operating a blast furnace, which comprises charging the blast furnace into the blast furnace so that it is in a state. 2. The amount of the lump iron ore used is adjusted according to the reduction pulverization index of the sinter ore and the residence time of the charge in the low temperature reduction zone of the furnace temperature of the blast furnace shaft portion of 500 to 700 ° C. The method of operating a blast furnace according to claim 1, wherein