JP2002266037A - Method for manufacturing sintered ore - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing sintered ore using a downward-suction-type sintering machine by which reduction in the yield of product sintered ore can be prevented without deteriorating the quality of the sintered ore even if high-alumina iron ore is blended in large quantities. SOLUTION: Raw materials are charged in such a way that the alumina content in height direction of a layer of raw materials for sintering is lowered from the upper surface downward. The equivalent average alumina content in the raw mixed materials is regulated so that it is higher by <=0.2% in the upper-layer part between the surface of the raw-material layer and a position at a prescribed depth one-fifth the thickness of the layer under the surface than in the lower-layer part between the bottom and a position at a prescribed height one-half the thickness of the raw-material layer. In the pretreatment of the raw materials: the raw mixed materials of relatively high alumina content and the raw mixed materials of relatively low alumina content are prepared; granulation is carried out so that the above high-alumina raw mixed materials become quasi-particles having particle size smaller than that of the above low-alumina raw mixed materials; and the resultant fine-grained high-alumina quasi-particles are charged on the upper-layer side, and the coarse-grained low-alumina quasi- particles are charged on the lower-layer side. In charging onto a pallet, a particle-size- segregation-forming charging equipment having screening function is used. The granulation is performed in such a way that the average particle size of the fine-grained high-alumina quasi-particles and that of the coarse-grained low-alumina quasi-particles take values within the shaded region of the figure, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for blast furnace operation using iron ore having a high alumina content as a raw material in an iron ore sintering ore production process using a downward suction sintering machine such as a Dwyroid type sintering machine. And a method for producing a sintered ore for obtaining a sintered ore.

[0002]

2. Description of the Related Art The quality of sinter used in a blast furnace as a raw material for steelmaking has a significant effect on the ventilation and liquid permeability in the furnace during the operation of the blast furnace, the reducibility, the stability of the blast furnace operation, and the like. The strength, reducibility, reduction resistance to pulverization, etc. of the concreting are strictly controlled. Further, in order to reduce the production cost of the sinter, the yield and productivity of the sinter are also important management items.

[0003] Fig. 6 shows a general production process of such an iron ore sintered ore used as a raw material for a blast furnace. Various powder ore is piled every brand in powder ore yards, the free CaO auxiliary material, containing SiO ₂ auxiliary materials, blending powder 22 mixed by bedding 21 method dust, and the carbonaceous material or the like at a predetermined ratio, including iron . The raw materials such as the blending powder 22, the plain iron ore 23, the limestone 24, the silica stone 25, the coke breeze 26, and the ore return 27 are mixed in the respective mixing tanks 2.
8, and the blended raw material 38 thus obtained is mixed with the water 30 by a mixer 29, humidified and mixed, granulated into pseudo particles 31, and coke powder 32 is added as appropriate. At 33, the pseudo particles 31 are packaged on the surface. The pseudo particles 34 thus prepared are used as a sintering raw material. The sintering raw material 35 is continuously supplied from the raw material feeder 11 through the chute 36 to the bedding ore 15 on the pallet 16 to a layer thickness of a constant height of about 500 to 700 mm to form a raw material layer in the form of a packed layer. To form The carbon material in the surface material of the raw material bed 37 thus formed is ignited by an ignition furnace, and the coke breeze mixed in the raw material is sequentially burned while sucking air downward from the upper layer of the raw material bed 37, and the combustion zone is formed. While moving from the upper layer to the lower layer, sintering and melting reactions are caused to sinter and agglomerate the sintering raw material. After cooling the fired sintered cake, it is crushed,
The sinter having a size of about 3 to 50 mm is used as a raw material for the blast furnace.

In order to make the quality of the sintered ore obtained in this way favorable and stable, hematite (main component: Fe ₂ O ₃ (hematite)) or magnetite (main component: Fe ₃ O) is conventionally used as a raw material. ₄ (magnetite)) has been used. Then, in order to obtain a sintered ore having a stable quality, it is general to use a blend of iron ores of brands having various properties as described above. However, in recent years,
The production of high quality iron ore is decreasing, and the use of iron ore containing a large amount of alumina is increasing accordingly. For example,
The average value of the Al ₂ O ₃ content of the sintered ore of the entire Japanese steel industry in 1999 was about 1.8 mass%, and the Al ₂ O ₃ content of the sintered ore will gradually increase in the future. It is expected that. However, as the Al ₂ O ₃ content in the sinter increases, the strength and the reduction powdering resistance of the sinter decrease. As a result, the sinter yield and productivity are reduced, and the blast furnace operation is hindered in stability. On the other hand, high-Al ₂ O ₃ iron ore, because it is cheaper than normal iron ore, the future high-Al ₂
Establishing technology for using O ₃ iron ore is one of the most important issues in blast furnace operation.

In the background described above, conventionally, for example, a method of adding a SiO ₂ component to dilute the Al ₂ O ₃ component in iron ore has been adopted. The demand for reduction has led to a reduction in the SiO ₂ content in the sinter. Therefore, the adverse effect of the increase in the Al ₂ O ₃ content on the sinter quality is becoming remarkable. On the other hand, in the current sintering and blast furnace operation, the Al ₂ O ₃ content in the sinter is strictly controlled in order to avoid deterioration of the sinter ore yield, productivity and product strength. That is the current situation.

Therefore, in the sinter ore production process, the following method has been proposed as a method for preventing a decrease in the yield of product sinter which occurs when a large amount of high alumina iron ore is blended, without lowering the quality. A proposal has been made.

[0007] For example, Japanese Patent Application Laid-Open No. 5-31254 discloses that a fluoride, barium compound or boron compound is mixed with a sintering raw material packed layer (referred to as a "raw material bed").
A method of adding and adding an appropriate amount to the portion 3 or the lower layer portion 2/3 (hereinafter referred to as "prior art 1") is disclosed.

Japanese Unexamined Patent Publication No. Hei 6-330192 discloses that a material containing metallic iron, for example, reduced iron powder, granulated pig iron, Dalai powder, or scrap iron is placed 200 m from the surface of the raw material bed.
A method of mixing and adding an appropriate amount below m (hereinafter referred to as “prior art 2”) is disclosed.

Japanese Patent Application Laid-Open No. 7-278684 describes that Fe
A method of blending and adding an appropriate amount of a magnetite ore or scale containing an appropriate amount of the O component to a region layer 200 mm or more below the surface of the raw material bed and 200 mm or more above the bottom layer (hereinafter referred to as “prior art 3”). ) Is disclosed.

Japanese Unexamined Patent Publication (Kokai) No. 6-271950 discloses that, for a high alumina iron ore having a predetermined crystal morphology, a large amount of limestone or quicklime is present around the iron ore so that A method of preferentially reacting an Al ₂ O ₃ component with a CaO component (hereinafter referred to as “prior art 4”) is disclosed.

In each of the above-mentioned prior arts, the fluidity of the melt generated during the sintering process of the sintering raw material is optimized, and a vent hole is formed in the raw material bed.
The aim is to improve the quality of the sinter. However, in Prior Art 1 to Prior Art 4, in any method, a raw material feeder (FIG. 6, reference numeral 11)
) Must be provided at two places, which results in the formation of discontinuous portions in the raw material bed with respect to the particle size and composition of the sintering raw material. As a result, there is a problem that the gas flow in the raw material bed becomes unstable and sintering becomes unstable.

[0012]

The prior arts 1 to 4 include:
There are problems as described above, and it cannot be said that this is a sufficient solution. Further, the principle of solving the problems of the inventions in the prior arts 1 to 4 is that, by optimizing the fluidity of the melt in the firing process from the intermediate layer to the lower region layer of the raw material bed, the vent hole is formed in the raw material bed. By forming the sinter, the quality of the sinter is improved to suppress a decrease in yield.

On the other hand, the inventors of the present invention have studied the prevention of a decrease in the yield of the product sinter when the high alumina iron ore is blended in a large amount in the sinter production process, by reducing the quality of the product sinter. The problems to be solved required to achieve without lowering are set as follows. That is, the main causes of the reduction in the yield and the quality of the product sintered ore when a large amount of high alumina iron ore is blended are as follows.

When the melt formed from the quasi-particles of the sintering raw material solidifies during sintering, the secondary hematite phase is crystallized, and Al ₂ O ₃ dissolved in this secondary hematite phase forms the secondary hematite phase. An internal strain is generated in the crystal, and this becomes a starting point of physical destruction of the melt solidification phase. In such a behavior phenomenon at the time of solidification of the melt, when the content of Al ₂ O ₃ in the pseudo particles of the sintering raw material increases, the amount of solid solution of Al ₂ O _{3 in} the secondary hematite phase increases. Due to the internal strain, the strength of the sintered ore decreases, and its resistance to reduction powdering deteriorates. Therefore, even when a large amount of iron ore having a high Al ₂ O ₃ content is used, the diffusion of the Al ₂ O ₃ component is suppressed and the solid solution amount of the Al ₂ O ₃ component in the secondary hematite phase is reduced. It is an object of the present invention to create a method capable of suppressing an increase in the number of fracture starting points formed in the solidification phase by suppressing the above.

Thus, an object of the present invention is to provide a method for producing a sintered ore for improving the sintering yield and productivity without reducing the quality of the product sintered ore by solving the above-mentioned problems. To provide.

[0016]

Means for Solving the Problems The inventors of the present invention have conducted tests and studies from the above viewpoints, and have obtained the following findings.

In the sinter ore production process using the downward suction type sintering machine, the present inventors have studied the temperature distribution in the raw material bed formed by the combustion zone moving from the upper part to the lower part in the raw material bed and the time lapse. By utilizing the characteristic of the change behavior of the temperature distribution, the diffusion of the Al ₂ O ₃ component can be suppressed as much as possible even when the Al ₂ O ₃ content in the pseudo particles of the sintering raw material is increased. Discovered that it was possible to reduce the amount of Al ₂ O ₃ dissolved in secondary hematite generated during solidification of the melt, and thus it was possible to suppress the destruction of the solidified phase. did. An outline of the process will be described.

1. The inner volume of the raw material charging part is 280mmφ
Using a pot-type firing test furnace with a height of 450 mm, the upper layer
And the lower layer_TwoO_ThreeSintered raw material packed bed with different content
Bed), ignite the upper layer surface and fire
The experiment was performed. At this time, the quasi-particle sinter
Al of the whole material_TwoO_ThreeThe average value of the content is calculated as
It is constant at 1.8 mass%, and 25 ma of the whole sintering raw material
ss% is charged to the upper layer of the raw material bed, and the remaining 75mas
s% was charged to the lower layer of the raw material bed. Al on the upper layer side_Two
O_ThreeContent and Al of lower layer side_TwoO_ThreeVarious combinations with content
The test is performed for the case where it is changed.
The sinter ore yield and reduction powdering resistance of the steel were evaluated. The result
The results are shown in FIG. Here, the horizontal axis in FIG.
Conversion Al _TwoO_ThreeIndicates the content.

As is apparent from FIG. 2, by increasing the alumina content in the sintering raw material in the upper layer of the raw material bed and lowering it in the lower layer, both the sinter yield and the reduction powdering resistance are reduced. It can be seen that the degree of improvement increases as the difference in the alumina content between the upper layer portion and the lower layer portion increases. When the alumina content in the upper layer is higher than the alumina content in the lower layer by 0.2 mass% or more, the sinter yield is 9%.
0% or more, and the low-temperature reduction powdering index RDI is 35% or less. The results obtained here show that under relatively low temperature and short time firing conditions in the upper layer of the raw material bed of the pot type firing test furnace, even if the Al ₂ O ₃ component in the sintering raw material becomes higher, This indicates that diffusion into the liquid is suppressed.

2. Next, an actual machine test was performed using a downward suction type sintering machine. Iron ore with relatively high alumina content was granulated into fine pseudo-particles, and iron ore with relatively low alumina content was granulated into coarse pseudo-particles. The weight ratio of high alumina iron ore / low alumina iron ore is 25/75. At that time, Al ₂ O ₃
The average value of the content is 1.8 mass% in terms of the raw material content.
, And the particle size ratio between the high alumina fine particles and the low alumina coarse particles is 0.5, 0.8, 1.
The raw material pseudo-particles of three levels of 0 were prepared. And
For each set raw material, after the fine particles and coarse particles are once mixed, when charging the sintering raw material, a segregation charging wire type screen chute, which is a particle size segregation forming charging device having a sieving function, is used. By charging the sintering raw material after the mixing into a pallet, fine particles were distributed on the upper layer side of the raw material bed and coarse particles were distributed on the lower layer side. However, in the test in which the particle size ratio (pseudo particle size ratio) is 1.0, the particle size distribution in the raw material bed is a particle size distribution limited to a relatively narrow range of the particle size distribution range of the pseudo particles, Moreover, the distribution of the Al ₂ O ₃ content in the raw material bed is not formed.
The sinter yield and reduction powdering resistance in the above three levels of tests were evaluated. The result is shown in FIG.

As apparent from FIG. 3, (a) the raw material bed
High-alumina iron ore fine particles in the upper layer
The low pseudo-alumina ore coarse particles are charged and distributed
(When the particle size ratio is 0.5, 0.8) and (b)
Relatively fine pseudo-particles in the upper part of the bed, and
Although relatively coarse pseudo-particles were charged and distributed, alumina
Regarding the content rate, the same
Compare with the case of one level (when the particle size ratio is 1.0)
In the case of (a), the sinter yield and reduction powdering resistance are better
It can be seen that both are improved. The result obtained here is
Basically important in the operation of the actual machine downward suction type sintering machine
Desirable raw material storage to ensure air permeability in a raw material bed
Even when the raw material particle size distribution in the bed is a precondition,
Relatively low temperature and short time baking in the upper part of the material bed
Under the conditions, Al in the sintering raw material _TwoO_ThreeIngredients get higher
Also indicates that diffusion into the melt is suppressed.
You.

The present invention has been made based on the above findings, actual machine tests, and studies thereof, and the gist is as follows.

According to a first aspect of the present invention, there is provided a method for producing a sintered ore using a downward suction type sintering machine, the method comprising the steps of: Is characterized in that the sintering raw material is charged into a pallet of the lower suction type sintering machine so that the alumina content of the lower sintering material packed layer is lower than the upper surface of the sintering raw material packed layer. Things.

According to a second aspect of the present invention, there is provided a method for producing a sintered ore according to the first aspect of the present invention, wherein a predetermined thickness of the upper portion of the sintering raw material packed layer is 1/5 or less. The average alumina content is adjusted so as to be 0.2 mass% or more higher than the average alumina content in the mixed raw material having a predetermined thickness of 1/2 or less of the lower layer portion of the sintered raw material packed layer. In particular, it has features.

In the invention of the present application, "the predetermined thickness of the upper layer portion of the sintering raw material-filled layer is not more than 1/5" means the following contents. That is, any given depth position may be used as long as it is within one-fifth of the thickness of the raw material packed layer from the upper surface of the sintered raw material packed layer to the lower part. Is the area up to the position. And
The “predetermined thickness equal to or less than one-half of the lower layer portion of the sintering raw material packed layer” is defined by the above definition, and is 分 の of the thickness of the sintering raw material packed layer upward from the bottom surface of the sintering raw material packed layer. Within the range of 1 or less, it is an arbitrary constant height position, and refers to a region from the bottom surface of the raw material packed layer to the above constant height position. Also,
The compounding raw material is the main raw material consisting of all iron ore (fine ore) and raw materials containing iron such as mill scale, blast furnace dust and converter dust generated in steel works, etc., and auxiliary raw material as slag-making agent such as fine limestone , Returned ore, and solid fuel such as coke breeze, which is equivalent to the dry weight, and does not include the added moisture for granulation. The water of crystallization in the iron ore is included in the weight of the raw material.

In a third aspect of the present invention, there is provided a method for manufacturing a sintered ore using a downward suction type sintering machine, wherein the alumina content is relatively reduced in a pre-treatment step of a sintering raw material. Prepare a high compounding material and a relatively low compounding material, granulate the compounding material whose alumina content is relatively high into pseudo particles having a smaller particle size than the compounding material whose alumina content is relatively low, The sintering material of the fine-grained high-alumina-content pseudo-particles thus granulated is charged into the upper layer of the sintering-material-packed layer, and the sintering material of the coarse-grained low-alumina-content pseudo-particles is sintered. It is characterized by being charged into the lower layer side of the raw material packed layer and firing.

According to a fourth aspect of the present invention, there is provided a method for producing a sintered ore using a downward suction type sintering machine, wherein the alumina content in the pre-treatment step of the sintering raw material is relatively small. A high compounding material and a relatively low compounding material are prepared, and a compounding material having a relatively high alumina content is prepared.
The alumina content is granulated into pseudo particles having a smaller particle size than the blended raw material, and the sintering raw material thus granulated is charged into a pallet of the lower suction type sintering machine. The present invention is characterized in that a sintering raw material packed layer is formed by using a particle size segregation forming charging device having a separating function.

According to a fifth aspect of the present invention, there is provided a method for producing a sintered ore according to the third or fourth aspect, further comprising the step of: So that the equivalent average alumina content in the blended raw material is 0.2 mass% or more higher than the reduced average alumina content in the blended raw material having a predetermined thickness of one half or less of the lower layer portion of the sintering raw material packed layer. The feature is that an adjustment operation is added.

According to a sixth aspect of the present invention, there is provided a method for producing a sintered ore according to any one of the third, fourth and fifth aspects of the present invention, The average particle size and the average particle size of the coarse low-alumina content pseudo-particles are characterized in that they are granulated so as to have a particle size within a range shown by oblique lines in FIG.

[0030]

Next, the present invention will be described with reference to the drawings.

FIG. 4 shows an example of the flow of a process for producing a sintered ore by mixing the high alumina iron ore of the present invention. In the figure, 1 is iron ore powder, 2 is high alumina iron ore powder, 3 is low alumina iron ore powder, 4 is returned ore, 5 is auxiliary material such as limestone,
6 and 7 are mixers, 61 and 71 are moisture, 8 is coke breeze, and 9 is a drum mixer. In the figure, in a granulation line 1, water 61 is added to a raw material blended with a high alumina iron ore powder 2 and a predetermined raw material, and mixed and mixed by a mixer 6.
It is granulated and granulated into high alumina fine-grain pseudo-particles 17. On the other hand, in the granulation line 2, the water 71 is added to the blended raw material of the low alumina iron ore powder 3 and the predetermined raw material, mixed and granulated by the mixer 7, and granulated into low alumina coarse pseudo particles 18.
The obtained pseudo-particles 17 and 18 were mixed, and coke breeze 8 was added thereto. The coke breeze 8 was packaged on the surface of the mixed pseudo-particles by a drum mixer 9 to prepare mixed pseudo-particles 19. I do.

[0032] the figure, by blending relatively high Al ₂ O ₃ content and high alumina iron ore, a relatively low Al ₂ O ₃ content low alumina ore in separate formulations line, The above-mentioned high alumina iron ore blending line granulates into relatively fine high alumina content pseudo particles, and the above low alumina iron ore blending line granulates into relatively coarse low alumina content pseudo particles. After sintering raw materials are prepared by mixing the obtained sintering raw material pseudo-particles once, a sintering raw material packed layer (raw material bed) is formed using a particle size segregation forming and charging apparatus. Things. As shown in FIG. 4, the relatively fine high alumina content pseudo-particles may be obtained by using only the high alumina content ore, or by using a large amount of the high alumina content ore and a small amount of the low alumina content ore. Ore may be used. On the other hand, the relatively coarse low-alumina-content pseudo-particles may use only the low-alumina-content ore as shown in FIG. Ore and a small amount of high alumina content ore may be used. In addition, it is not always necessary to granulate the fine high-alumina content pseudo-particles and the coarse-particle low-alumina content pseudo-particles in separate lines, or to mix them in separate lines, and the Raw material blending and granulation may be performed on the same line under a schedule, or only raw material blending may be performed on the same line.

The mixed pseudo particles 19 thus prepared are used as a sintering raw material. Raw material feeder 1
1 to a screen type chute 12, which is a particle size segregation formation charging apparatus, and the sintering raw material is dropped and charged on a pallet 16 of a sintering machine by the screen type chute 12,
A sintering raw material packed layer having a layer thickness of about 500 to 700 mm in height,
That is, the raw material bed 20 is formed. The screen-type chute 12 is provided so as to be inclined downward in a direction opposite to the traveling direction of the pallet 16 (the direction in the drawing), and a wire (or rod) parallel to the width direction of the pallet 16 is moved from the upper portion to the lower portion of the pallet 16. It is provided so that the interval becomes wider as it goes. The raw material bed 20 of the sintering raw material 10 is formed by the screen-type chute 12 with the particle size segregation in which fine particles are distributed in the upper layer and coarse particles are distributed in the lower layer. The distribution of the alumina component in the height direction in the raw material bed 20 thus formed is such that the upper layer has a fine-grain pseudo-particle layer having a high alumina content (high alumina raw material layer 13) and the lower layer has a coarse-grain pseudo-particle having a low alumina content. The particle layer (low alumina raw material layer 14) will occupy. However, the raw material bed 20 is formed by laying the bedding ore 15 having a predetermined coarse particle size on the upper surface of the pallet 16 to a predetermined thickness and forming the bed ore 15 thereon.
The air permeability of the raw material bed 20 is ensured. While moving the pallet 16 in the direction of the arrow, the upper surface layer of the raw material bed is ignited in an ignition furnace (not shown), and the inside of the raw material bed 20 is sucked downward, thereby burning the coke dust in the sintering raw material. Then, the sintering raw material of the raw material bed 20 is moved from the upper layer to the lower layer in the combustion zone, and the entire raw material bed 20 is fired.

In the above-mentioned firing process, the upper layer of the raw material bed 20 after the ignition is sintered at a low temperature for a short time by the atmosphere of the atmosphere flowing in from above. Is sintered at a relatively high temperature for a long time. Therefore, even if the high alumina raw material layer 13 is formed in the upper layer, the diffusion of the Al ₂ O ₃ component is suppressed, so that the Al in the secondary hematite accompanying the solidification of the melt is suppressed.
The solid solution amount of the ₂ O ₃ component is suppressed, and the strength of the sintered ore is maintained. On the other hand, in the lower part of the raw material bed, even if sintering is performed at a high temperature for a long time, the low alumina raw material layer 14 is formed.
Alternatively, when the Al ₂ O ₃ content is relatively low, the strength of the sintered ore is improved. As a result, regarding the entire raw material bed, it is possible to improve the yield of the sinter ore and improve its resistance to pulverization and reduction.

In the above-described sinter ore production flow (FIG. 4), if the particle size of the high alumina iron ore powder 2 in the granulation line 1 is small, such as fine powder, the mixer 6
In order to uniformly mix with other ingredients and water, the mixer 6 may be an Erich mixer or a Loedige mixer having a high-speed rotation function of a stirring blade, or a kneading machine having a function similar thereto. It is desirable to perform a kneading process using a processing device.
On the other hand, when the particle size of the low alumina iron ore powder 2 in the granulation line 2 is relatively large, a good granulation effect can be obtained by using a disk pelletizer as the mixer 7.

Next, desirable conditions for the particle size of the pseudo-particles to be prepared using the raw material in which the high alumina iron ore and the low alumina iron ore are blended in the present invention will be described.

In general, in the sintering operation of iron ore using a downward suction sintering machine, the quasi-particle diameter of the sintering raw material forming the raw material bed has conventionally been required to ensure stable operation while ensuring air permeability. Ideally, the lower limit particle size is ideally set to about 1.5 mm. However, in the granulation process in actual operation, it is difficult to eliminate the incorporation of a fine powder having a particle size of less than 1.5 mm. Is not real. On the other hand, the upper limit particle size is desirably about 5 mm.

As described above, in the present invention, the relatively high pseudo-particles having a high alumina content and the relatively low pseudo-particles having a relatively low alumina content are charged and distributed in the upper layer of the raw material bed and in the lower layer, respectively. It is necessary. On the other hand, in the sintering operation of iron ore using a downward suction type sintering machine, as described above, considering the actual state of the relationship between the height position of the raw material bed and the sintering temperature and duration, the upper layer is fine. It is desirable to charge and distribute the granular raw material in the lower layer. Therefore, an advantageous method for forming the content distribution of the Al ₂ O ₃ component in the height direction of the raw material bed to be high in the upper layer and low in the lower layer is to finely mix the mixed raw material having a high alumina content. It is preferable to granulate the raw material having a low alumina content into relatively coarse particles, and charge the mixed pseudo-particles obtained by mixing the both using a particle size segregation charging device (particle size segregation charging). Fine particles are distributed in the upper part of the raw material bed and coarse particles are distributed in the lower part of the raw material bed).

As described above, the upper limit of the particle size of the pseudo particles in the raw material bed is desirably about 5 mm, as described above. The particle size is desirably 5 mm or less.

As described above, the desirable range of the pseudo-particle diameter of the high alumina content of fine particles and the pseudo-particle diameter of the low alumina content of the coarse particles in the present invention is preferably within the range indicated by the hatched portion in FIG. Understand.

The effect of the distribution state in which the content of the Al ₂ O ₃ component in the raw material bed in the present invention decreases from the upper layer toward the lower layer on the sinter yield and the resistance to reduction powdering will be evaluated. Therefore, the following test was performed using the pot-type firing test furnace described in FIG. Specify the two regions in the material bed height direction of the pot calcining test furnace, the average Al ₂ O ₃ content and its two high and low average Al ₂ O ₃ content of the iron ore in the upper and lower two regions The relationship between the difference in sinter ore and the sinter yield and resistance to reduction powdering was tested. At this time, the iron ore Al of the whole pseudo-particle sintering raw material of the raw material bed
The average value of the ₂ O ₃ content was kept constant at 1.8 mass%.
As a result, the converted average alumina content in the blended raw material in the pseudo-particles having a predetermined thickness of 1/5 or less of the upper layer portion of the raw material bed (the average Al ₂ O ₃ content in the predetermined thickness at the blended raw material stage was calculated as The same applies to the following), but the average Al ₂ in the blended raw material in the pseudo-particles having a predetermined thickness of one half or less of the lower layer portion of the raw material bed.
By adjusting the content of O ₃ to be 0.2 mass% or more higher than the O ₃ content, it is possible to obtain a result in which the sintered ore yield is approximately 90% or more and the low-temperature reduction powdering index RDI is approximately 40% or less. did it. Accordingly, the relationship between the average Al ₂ O ₃ content in the mixed raw material in the pseudo particles having a predetermined thickness of 1/5 or less of the upper layer portion of the raw material bed and a predetermined thickness of 1/2 or less of the lower layer portion is shown in FIG. It is desirable to adjust within the range shown by the oblique line in FIG.

[0042]

The present invention will be described in more detail with reference to examples.

[Test 1] A pretreatment was performed using the sintering compound raw materials shown in Table 1 by a flow according to the flow for implementing the method for producing a sintered ore of the present invention shown in FIG. In the pre-treatment of the raw material, a large amount of iron ore (A ore) having a relatively high alumina content is blended into granulated fine particles, and iron ore (B ore B) having a relatively low alumina content is mixed. And C ore) were granulated into coarse pseudo particles. The average Al ₂ O ₃ content in all the raw materials for sintering was 1.80 m.
ass%. The prepared quasi-particle sintering raw material 10 is charged on the bed ore 15 of the pallet 16 using a particle size segregation forming charging device (screen type chute 12), and the raw material bed 20 having a height of 600 mm is formed. Formed. Fine-grained raw material was distributed in the upper part of the raw material bed 20 and coarse-grained raw material was distributed in the lower part, and a sinter production test operation was performed using a downward suction type sintering machine (Examples 1 and 2). ).

[0044]

[Table 1]

Example 1: An average pseudo particle diameter of 3.2 mm and an average Al ₂ O ₃ content of 2.7 mass as calculated in the compounding raw material.
%, The fine-grained high alumina raw material is 25% by weight,
The average pseudo particle diameter is 4.3 mm and the average A in the compounding raw material
75% by weight of a coarse low-alumina raw material having an l ₂ O ₃ content of 1.5 mass% was mixed with a drum mixer,
Pallet 1 while segregating particle size with screen chute
6 to form a raw material bed 20. as a result,
The average alumina content in the range from the upper surface of the raw material layer to the upper layer side 1/5 height (however, this is "average alumina content in terms of the blended raw material". The same applies to the following Examples and Comparative Examples). 2.08 mass%, the average alumina content in the range from the bottom surface of the raw material layer to the lower half height is 1.6.
5% by mass, the difference between the two was 0.43% by mass, and the upper layer side was higher.

Example 2 The average pseudo-particle diameter is 3.2 mm and the average Al ₂ O ₃ content in the raw materials is 2.6 mass.
%, The fine-grained high alumina raw material is 35% by weight,
The average pseudo particle diameter is 4.3 mm and the average A in the compounding raw material
A coarse-grained low-alumina raw material having a l ₂ O ₃ content of 1.4 mass% and a weight ratio of 65% were mixed with a drum mixer,
Pallet 1 while segregating particle size with screen chute
6 to form a raw material bed 20. as a result,
The average alumina content in the range from the upper surface of the raw material layer to the upper 1/5 height is 1.88 mass%, and the average alumina content in the range from the lower surface of the raw material layer to the lower 1/2 height is 1.73 mass%. And the difference between them is 0.15mas
The upper layer side was higher at s%.

As a comparative example, the iron ore having a relatively high alumina content used in Examples 1 and 2 was used according to the conventional general sinter production flow shown in FIG. A sinter production test operation was performed using the stone 2 and the iron ore 3 having a relatively low alumina content. However, when the sintering raw material 35 was charged, the same screen type chute 12 as in Examples 1 and 2 was used, and the fine particles were segregated in the upper layer and the coarse particles were distributed in the lower layer.

Comparative Example 1 A sintering raw material having an average pseudo particle diameter of 4.0 mm and an average Al ₂ O ₃ content of 1.80 mass% was charged. In this case, the distribution of the alumina content in the height direction in the raw material bed 20 is as follows.
The average alumina content in the range up to / 5 height is 1.78 m
ass%, the average alumina content in the range from the bottom surface of the raw material layer to the lower half height is 1.82 mass%,
There was almost no difference in the alumina content between the upper layer side and the lower layer side (see Table 1).

Other conditions in the sintering operation were the same in the example and the comparative example. FIG. 5 shows the operation results in Example 1, Example 2, and Comparative Example 1.
In Example 1 and Example 2, the sinter ore yield was improved by 5% and 3%, respectively, as compared with Comparative Example 1, and the reduction dusting resistance was 7%, as compared with Comparative Example 1, in terms of RDI. And 3
%Improved. These results show that, as described in FIG. 2, the alumina content in the sintering raw material is increased in the upper part of the raw material bed and lowered in the lower part, thereby improving the sinter yield and the reduction pulverization resistance. Indicate that both improved.

[Test 2] Examples 3 to 5, which are tests within the scope of the present invention, and Comparative Example 2, which is a test outside the scope of the present invention, were carried out in accordance with Test 1 described above. However, the alumina content of the iron ore and the ore returned was partially different from that in the test 1. Table 2 shows the sintering compound raw material, the granulated pseudo-particle diameter, and the average Al in the compounding raw material in each test.
Shows the ₂ O ₃ content.

[0051]

[Table 2]

That is, the average Al ₂ O ₃ content in all the raw materials for sintering in each test was increased to a constant value of 2.20 mass%, and the fine particles in Examples 3 to 5 were each used. The difference from the condition of Test 1 is that the average Al ₂ O ₃ content of each of the high alumina raw material and the coarse-grain low alumina raw material was increased.

FIG. 5 also shows the operation results in Examples 3 to 5 and Comparative Example 2.

First, Comparative Example 2 is compared with Comparative Example 1. ratio
In Comparative Example 2, the average Al_TwoO_ThreeContent rate
0.4 mass% higher than Comparative Example 1,
Yield is greatly reduced, and reduction powdering resistance is also significantly deteriorated.
Was. However, in Examples 3 to 5, in Example 1
The present invention is applied according to the method in
The fine-grain high-alumina material layer is in the upper layer, and the coarse-grain
Since the lumina material layer was formed,
Both sinter yield and reduction powdering resistance were improved. here,
The test conditions in Example 3 were such that the entire raw material bed was replaced with the mixed raw material.
Average Al _TwoO_ThreeConducted at a content rate of 2.20 mass%
The same was maintained as in Examples 4 and 5. Matters to note
In Example 3 under such conditions,
Average Al in the whole compounding raw material conversion_TwoO_ThreeContent is comparative example
Even if it rises significantly from 1 (average Al_TwoO_ThreeIncreasing content
Value = 0.4 mass%), sinter yield and reduction powdering resistance
Both were maintained at the same level as Comparative Example 1.
It is.

As shown in Table 2, the distribution of the alumina content in the height direction in the raw material bed was adjusted to be higher in the upper layer and lower in the lower layer, so that the sintering under low-temperature and short-time conditions was carried out. The application range of the effect of suppressing the diffusion of the Al ₂ O ₃ component in the raw material into the produced melt during the firing process of the raw material layer is limited to an appropriate range in the upper layer of the raw material bed, and within this range is within an appropriate range. By forming a raw material layer having as high an Al ₂ O ₃ content as possible in the above, the sinter ore yield and the reduction pulverization resistance can both be at a desired level even when an iron ore having a higher Al ₂ O ₃ content is used. It indicates that it can be maintained.

The appropriate conditions for the Al ₂ O ₃ content in the sintering raw material and the distribution region thereof in the raw material bed as described above are determined by the main operating conditions of each downward suction type sintering machine, for example, the production rate Depends on the specific conditions of the operation, such as the temperature distribution in the raw material bed depending on the composition of the suction gas, the amount of carbonaceous material added, the grade and gangue of iron ore, the mixing ratio of so-called high crystal water ore, and the gas flow rate I do. Therefore, it is desirable to determine the above appropriate conditions according to the unique conditions of the operation.

[0057]

According to the present invention, the sintering operation, sinter ore quality and yield can be improved by increasing the alumina component in the sintering raw material in the iron ore sinter production process using the downward suction sintering machine. , It is possible to suppress adverse effects on productivity and the like. As a result, it is possible to increase the amount of inexpensive iron ore containing a large amount of alumina component, thereby contributing to a reduction in the production cost of sinter ore, stabilizing the supply and demand of iron ore raw materials, and further improving the sinter ore progress. This makes it possible to improve the distillation and productivity and the resistance to reduction pulverization. The present invention can provide a method for producing a sintered ore capable of exhibiting such effects,
An industrially useful effect is provided.

[Brief description of the drawings]

FIG. 1 is a view showing a desirable limit range (range indicated by oblique lines in FIG. 1) between a high-alumina content pseudo-particle diameter of fine particles and a low-alumina content pseudo-particle diameter of coarse particles in the present invention.

FIG. 2 The average Al ₂ O ₃ content of the entire thickness of the raw material bed is kept constant, and the upper layer Al ₂ O ₃ content (average
₂ O ₃ content, if allowed hereinafter the same) and change the underlying Al ₂ O ₃ content in the various levels, is a graph illustrating the effect on ShoyuikofuTome and RDI.

[FIG. 3] The average Al ₂ O ₃ content of the entire raw material bed thickness is kept constant, and iron ore having a relatively high alumina content is granulated into fine pseudo-particles and distributed in the upper layer, and relatively low. 4 is a graph illustrating the effect of the particle size ratio of pseudo-particles on the sinter yield and RDI when iron ore having an alumina content is granulated into coarse pseudo-particles and distributed in the lower layer.

FIG. 4 is a diagram showing an example of a flow of a process of producing a sintered ore by mixing the high alumina iron ore of the present invention.

FIG. 5 is a graph showing an example of the effect of improving sinter ore yield and RDI by implementing the present invention.

FIG. 6 is a flow chart showing a general production process of a conventional iron ore sintered ore.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 iron ore powder 2 high alumina iron ore powder 3 low alumina iron ore powder 4 returned ore 5 auxiliary material 6, 7 mixer 61, 71 moisture 8 powder coke 9 drum mixer 10 sintering raw material 11 raw material feeder 12 screen chute 13 high alumina raw material layer 14 Low alumina raw material layer 15 Bed ore 16 Pallet 17 High alumina fine-grained pseudo-particles 18 Low alumina coarse-grained pseudo-particles 19 Mixed pseudo-particles 20 Raw material bed 21 Bedging 22 Blending powder 23 Simple powdery iron ore 24 Limestone 25 Silica 26 Coke powder 27 Returning ore 28 Compounding tank 29 Mixer 30 Water 31 Pseudo particle 32 Coke powder 33 Drum mixer 34 Pseudo particle 35 Sintering material 36 Shoot 37 Material bed 38, 39, 40 Compounding material

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[Procedure amendment]

[Submission date] March 29, 2001 (2001.3.2)
9)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

[Procedure amendment]

[Submission date] August 31, 2001 (2001.8.3)
1)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Koichi Ichikawa 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. F-term (reference) 4K001 AA10 BA02 CA39 CA41 GA10 GB01

Claims (6)

[Claims] 1. A method for producing a sintered ore using a downward suction type sintering machine, wherein the alumina content in the sintering raw material in the height direction of the sintering raw material packed layer is higher than the sintering raw material packed layer. A method for producing a sintered ore, comprising charging the sintering raw material into a pallet of the downward suction type sintering machine so that the alumina content of the lower layer portion is lower than the surface. 2. The reduced average alumina content in a blended raw material having a predetermined thickness of 1/5 or less of the upper layer portion of the sintering raw material packed layer is as follows:
0.2mass lower than the equivalent average alumina content in the blended raw material having a predetermined thickness of one half or less of the lower layer portion of the sintering raw material packed layer.
The method for producing a sintered ore according to claim 1, wherein the sinter is adjusted so as to be higher than s%. 3. A method for producing a sintered ore using a downward suction type sintering machine, wherein a compounded material having a relatively high alumina content and a compounded material having a relatively low alumina content are prepared in a pretreatment step of the sintering material. The raw material having a relatively high alumina content is granulated into pseudo particles having a smaller particle size than the raw material having a relatively low alumina content. The sintering raw material of the particles is loaded on the upper layer side of the sintering raw material filling layer, and the sintering raw material of the coarse-grained low alumina content pseudo particles is charged on the lower layer side of the sintering raw material packed layer and fired. A method for producing a sintered ore. 4. A method for producing a sintered ore using a downward suction type sintering machine, wherein a compounded material having a relatively high alumina content and a compounded material having a relatively low alumina content are prepared in a pretreatment step of the sintering material. The raw material having a relatively high alumina content is granulated into pseudo particles having a smaller particle size than the raw material having a relatively low alumina content, and the sintered raw material thus granulated is subjected to the downward suction method. When charging the pallet of the sintering machine, characterized by forming a sintering raw material packed layer using a particle size segregation forming charging device having a sieving function,
Sinter production method. 5. The method for producing a sintered ore according to claim 3 or 4, further comprising:
The average alumina content in the mixed raw material having the following predetermined thickness is 0.2 m less than the average alumina content in the mixed raw material having a predetermined thickness of one half or less of the lower layer portion of the sintering raw material packed layer.
A method for producing a sintered ore, characterized by adding an operation of adjusting so as to be higher than ass%. 6. The average particle diameter of the fine-grained high alumina content pseudo-particles and the average particle diameter of the coarse-grained low alumina content pseudo-particles are within the range indicated by the hatched area in FIG. The method for producing a sintered ore according to any one of claims 3, 4, and 5, wherein granulation is performed so as to have a particle diameter.