Sintered ore manufacturing method and sintered ore manufacturing equipment

Abstract

To provide a method for producing sintered ore, which can reduce the unit requirement of coke in the production of sintered ore by specifying a heat index necessary and sufficient for sintering a sintering raw material corresponding to the layer height of a charging layer, and to provide a facility for producing sintered ore.SOLUTION: The method for producing sintered ore includes: a granulation step of granulating a sintering raw material containing an iron-containing raw material, coke, and a CaO-containing raw material by a granulator to form granulated particles; a charging layer forming step of forming a charging layer of the sintering raw material by charging the granulated particles into an endlessly moving pallet by a raw material supply device of a sintering machine; a sintering step of igniting the coke contained in the surface layer of the charging layer in an ignition furnace located downstream of the raw material supply device and burning the coke by sucking air in the charging layer in a wind-box provided below the pallet to make the charging layer a sinter cake; and a crushing step of crushing the sinter cake to form sintered ore. In the charging layer forming step, the charging layer is formed so that a thermal index of an upper layer of the charging layer is in a range of 30K min to 300K min.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for producing sintered ore, which is a raw material for a blast furnace, and to a production facility for sintered ore. [Background technology]

[0002] In recent years, the steel industry has been required to reduce CO2 emissions in order to reduce its environmental impact. Sinter, one of the raw materials for blast furnaces, is produced by adding a few percent of water to iron ore, the main raw material, and auxiliary materials containing CaO such as limestone, auxiliary materials containing SiO2 such as silica, and solid fuel such as coke, and then mixing and granulating the mixture to form pseudo-granules, which are then sintered using the heat from the combustion of the solid fuel. Most of the CO2 emitted in the sintering process is generated when the coke used as solid fuel is burned, so there is a need to reduce the amount of coke used in the sintering process.

[0003] However, reducing the proportion of coke in the sintering raw materials leads to insufficient melting due to a decrease in the amount of heat during sintering, increases the amount of powder generated after crushing the sinter cake, and reduces the product yield in the sintering process. Therefore, reducing the amount of coke too much reduces the product yield in the sintering process and actually increases the coke consumption rate. Here, the coke consumption rate is the amount of coke required to produce 1 ton of sintered ore, and is defined by the following formula. Coke consumption rate (kg / t-sinter) = Coke consumption (kg) / Finished sinter production (t-sinter)

[0004] In addition, during the sintering process, sintering proceeds from the upper layer downward while air is drawn downward from the upper layer of the sintering bed. Therefore, during sintering of the upper layer of the sintering bed, room temperature air is drawn in, and the temperature is lowered by the air, which tends to result in a lower product yield compared to the lower layer. Therefore, to obtain a good product yield, it is necessary to increase the coke content in the upper layer of the sintering bed compared to the lower layer, thereby increasing the temperature in the upper layer during sintering.

[0005] As a method for producing sintered ore in which coke is segregated in the upper layer of the sintering bed, Patent Document 1 discloses a method for producing sintered ore in which the particle size of the solid fuel is adjusted so that particles of 1 to 3 mm account for 50 mass% or more, and the solid fuel content in the surface layer is 1.08 to 1.42 times the solid fuel content in the deeper part. According to Patent Document 1, from the viewpoint of improving product yield, the higher the solid fuel content in the upper layer of the sintering bed, the better, but if the solid fuel content is too high, the sintering rate will decrease. For this reason, it is stated that good productivity can be achieved by setting the solid fuel content in the upper layer of the sintering bed within the above range.

[0006] Furthermore, Patent Document 2 discloses a method for producing sintered ore in which the solid fuel content is 4.0 to 5.5 mass% in the upper layer of the sintering layer and 3.0 to 3.3 mass% in the lower layer of the sintering layer. According to Patent Document 2, increasing the solid fuel content in the upper layer of the sintering layer increases the airflow resistance of the upper layer and reduces the sintering rate, but simultaneously reducing the solid fuel in the lower layer of the sintering layer reduces the airflow resistance in the lower layer of the sintering layer, thereby improving the sintering rate and achieving good productivity. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 5-98358 [Patent Document 2] Patent No. 5811936 [Patent Document 3] Patent No. 6364940 [Patent Document 4] Patent No. 2982128 [Patent Document 5] Japanese Patent Application Publication No. 10-330854 Summary of the Invention [Problem to be solved by the invention]

[0008] The coke segregation amounts disclosed in Patent Documents 1 and 2 are determined with the aim of improving sintering speed and increasing productivity, but are not intended to minimize coke consumption and reduce coke consumption per unit of production. Furthermore, product yield depends on the in-bed temperature during sintering and the time maintained at high temperatures, particularly on the heat index, which is the time integral of the in-bed temperature over a time range indicating temperatures above 1200°C. The higher the coke content in each layer of the sintering bed, the greater the heat generated during sintering and the higher the heat index. However, as mentioned above, the upper layers of the sintering bed are cooled by air more than the lower layers, so the heat index of the upper layers is smaller than that of the lower layers even if the coke content is the same. Therefore, even if the coke segregation amount in each layer of the sintering bed is determined, it may not necessarily fall within the target heat index range depending on the environment in which the sintering machine is installed. The present invention has been made in view of the above-mentioned problems, and its object is to provide a method and equipment for producing sintered ore that can reduce the coke consumption rate in the production of sintered ore by specifying a heat index that is necessary and sufficient for sintering the sintering raw materials in accordance with the bed height of the charging bed, and sintering the sintering raw materials with the heat amount that corresponds to the heat index. [Means for solving the problem]

[0009] The means for solving the above problems are as follows. [1] A method for producing sintered ore, comprising: a granulation step of granulating sintering raw materials containing iron-containing raw materials, coke, and CaO-containing raw materials in a granulator to form granulated particles; a charging bed formation step of charging the granulated particles onto an endless moving pallet using a raw material supply device of the sintering machine to form a charging bed of the sintering raw materials; a sintering step of igniting the coke contained in the surface layer of the charging bed in an ignition furnace provided downstream of the raw material supply device and burning the coke by sucking air from the charging bed using a wind box provided below the pallet to form a sintered cake from the charging bed; and a crushing step of crushing the sintered cake to form sintered ore, wherein in the charging bed formation step, the charging bed is formed so that the heat index of the upper layer of the charging bed is within a range of 30 K·min to 300 K·min. [2] The method for producing sintered ore according to [1], wherein in the sintering bed forming step, the sintering bed is formed so that the thermal index of the lower layer of the sintering bed is within a range of 400 K·min or more and 1000 K·min or less. [3] The method for producing sintered ore described in [1], wherein a correspondence relationship between the coke content in the upper layer and a heat index is determined in advance, and in the sintering layer formation step, the coke content in the upper layer is identified using the correspondence relationship, and the sintering layer is formed so that the coke content in the upper layer becomes the identified coke content. [4] A method for producing sintered ore according to [2], wherein a correspondence relationship between the coke content in the upper layer and the lower layer and a heat index is determined in advance, and in the charging layer formation step, the coke content in the upper layer and the lower layer is identified using the correspondence relationship, and the charging layer is formed so that the coke content in the upper layer and the lower layer becomes the identified coke content. [5] A sinter ore manufacturing facility comprising: a granulator that granulates sintering raw materials including iron-containing raw materials, coke, and CaO-containing raw materials using the granulator to form granulated particles; an endless moving pallet; a raw material supply device that charges the granulated particles onto the pallet to form a charging layer of the sintering raw materials; an ignition furnace that ignites the coke contained in the surface layer of the charging layer; a wind box that is provided below the pallet and sucks air from within the charging layer, and a sintering machine that sinters the charging layer to form a sintered cake; a crusher that crushes the sintered cake to form sintered ore; and a control device that controls the operation of the granulator, sintering machine, and crusher, wherein the control device controls the sintering machine so that the heat index in the upper layer of the charging layer is within the range of 30 K·min to 300 K·min. [6] The sintered ore manufacturing equipment according to [5], wherein the control device controls the sintering machine so that the heat index in the lower layer of the sintering bed is within a range of 400 K·min or more and 1000 K·min or less. [7] The sintered ore manufacturing equipment described in [5], wherein the control device identifies the coke content of the upper layer using a correspondence relationship between the coke content in the upper layer and a heat index, and controls the sintering machine so that the coke content in the upper layer becomes the identified coke content. [8] The sintered ore manufacturing equipment described in [6], wherein the control device identifies the coke content of the upper layer and the lower layer using a correspondence relationship between the coke content in the upper layer and the lower layer and a heat index, and controls the sintering machine so that the coke content in the upper layer and the lower layer becomes the identified coke content. [Effects of the Invention]

[0010] According to the present invention, by forming a charging bed so that the thermal index during sintering falls within a predetermined range, it becomes possible to sinter the raw materials with the amount of heat necessary and sufficient for sintering, thereby realizing a reduction in the coke consumption rate in the production of sintered ore. [Brief explanation of the drawings]

[0011] [Figure 1]FIG. 1 is a schematic diagram showing a sintered ore production facility 10 in which the sintered ore production method according to this embodiment can be implemented. [Figure 2] Figure 2 is a graph showing the relationship between the heat index of the upper layer and product yield. [Figure 3] Figure 3 is a graph showing the relationship between the heat index of the lower layer and product yield. [Figure 4] FIG. 4 is a graph showing the product yields and coke consumption rates of the upper and lower layers in Tests 1 to 5. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described below with reference to an embodiment. Fig. 1 is a schematic diagram showing a sintered ore production facility 10 in which a sintered ore production method according to this embodiment can be implemented. The sintered ore production facility 10 includes a granulator 16, a sintering machine 20, a crusher 30, and a control device 40.

[0013] The granulator 16 granulates the sintering raw material 12, which includes the iron-containing raw material, coke powder, and CaO-containing raw material, to form granulated particles 18. When the granulator 16 granulates the granulated particles 18, granulation water 14 is added to the sintering raw material 12. This process is the granulation step. The granulated particles 18 granulated by the granulator 16 are transported to a sintering machine 20. The iron-containing raw material is, for example, iron ore or dust generated in a steel mill. The CaO-containing raw material is, for example, quicklime, limestone, or slag.

[0014] The sintering machine 20 is, for example, a Dwight Lloyd type sintering machine. The sintering machine 20 includes a raw material supply device 21, a pallet 22, a coke content adjusting device 23, a cutoff plate 24, an ignition furnace 25, and a wind box 26. The raw material supply device 21 charges the granulated particles 18 into the pallet 22.

[0015] The pallet 22 is an endless movable pallet. Granulated particles 18 are charged onto the pallet 22 from the raw material supply device 21, and the coke content in the layer is adjusted by the coke content adjusting device 23, so that a charging layer of sinter raw materials 12 is formed within the pallet 22. The cut-off plate 24 flattens the surface of the charging layer and adjusts the thickness of the charging layer to a predetermined target layer thickness. This process is the charging layer formation step.

[0016] In the sintered ore manufacturing method according to this embodiment, the sintering layer is formed so that the thermal index of the upper layer is in the range of 30 K·min to 300 K·min. This allows the upper layer to be sintered with a sufficient amount of heat for sintering, improving the product yield in the upper layer and reducing the coke consumption rate. Here, the upper layer of the sintering layer refers to the region extending 200 mm below the surface of the sintering layer. The thermal index is the time integral of the temperature in the sintering layer during the time period when the temperature in the sintering layer is 1200°C or higher. It is more preferable to form the upper layer of the sintering layer so that the thermal index of the upper layer is in the range of 100 K·min to 200 K·min. This further improves the product yield in the upper layer of the sintering layer and reduces the coke consumption rate.

[0017] A coke content adjusting device 23 is used to keep the heat index of the upper layer of the sintering bed within a predetermined range. The coke content adjusting device 23 is, for example, a blower described in Patent Document 3. The coke content charged in the upper layer of the sintering bed can be controlled by including coke particles in the sintering raw materials that fall onto the pallet 22 and controlling the flow rate of the coke segregation gas that is blown onto the sintering raw materials from the blower.

[0018] The coke content adjusting device 23 may also be a pulverized fuel spraying device described in Patent Document 4. By using the pulverized fuel spraying device to spray coke from above, the coke content charged in the upper layer of the charging bed can be controlled. Furthermore, the coke content adjusting device 23 may also be a coke hopper provided in the raw material supply device 21 described in Patent Document 5. By controlling the opening and closing of the opening of the coke hopper, the coke content charged in the upper layer of the charging bed can be controlled. In this way, when additional coke is charged in the sintering machine in addition to the coke contained in the sintering raw material, the amount of coke to be charged in the sintering raw material can be reduced by that amount.

[0019] Furthermore, it is preferable to form the sintering bed so that the thermal index of the lower layer is within the range of 400 K·min to 1000 K·min. This allows the lower layer to be sintered with a sufficient amount of heat for sintering, improving the product yield in the lower layer and reducing the coke consumption rate. The method for setting the thermal index of the lower layer to the range of 400 K·min to 1000 K·min can be carried out in the same manner as for the upper layer. Here, the lower layer of the sintering bed refers to the region from the bottom of the sintering bed to 200 mm above. It is more preferable to form the lower layer of the sintering bed so that the thermal index of the lower layer is within the range of 600 K·min to 800 K·min. This allows the product yield in the lower layer of the sintering bed to be further improved and the coke consumption rate to be further reduced.

[0020] The ignition furnace 25 is provided downstream of the raw material supply device 21 and ignites the coke contained in the surface layer of the sintering bed. The wind box 26 is provided below the pallet 22 and draws the air downward from within the sintering bed formed within the pallet 22. When the wind box 26 draws the air downward from within the sintering bed, the combustion and melting zone within the sintering bed moves downward from the sintering bed. As the pallet 22 moves, the combustion and melting zone within the sintering bed moves downward, and the sintering raw materials 12 in the sintering bed are sintered. A sintered cake is obtained by sintering the sintering raw materials 12. This process is the sintering step.

[0021] The crusher 30 crushes the sintered cake discharged from the sintering machine 20 into crushed sintered cakes. The crushed sintered cakes are cooled and sized to produce sintered ore 32. This process is the crushing step.

[0022] The control device 40 is, for example, a general-purpose computer such as a workstation or a personal computer. The control device 40 has a control unit 41 and a memory unit 42. The control unit 41 is, for example, a CPU or the like, and controls the operations of the granulator 16, the sintering machine 20, and the crusher 30 by executing programs read from the memory unit 42. The memory unit 42 is, for example, an updatable flash memory, a built-in hard disk or a hard disk connected via a data communication terminal, an information recording medium such as a memory card, and a read / write device for the information recording medium. The memory unit 42 stores programs for the control unit 41 to execute each function, data used by the programs, etc.

[0023] The coke contents in the upper and lower layers that can be made within the range of the target heat index can be determined by previously determining a regression equation showing the correspondence relationship between the coke content and the heat index for each of the upper and lower layers of the charging bed through experiments or the like, and then specifying the coke contents using the corresponding relationship. The regression equations showing the correspondence relationship between the coke content and the heat index for the upper and lower layers are determined in advance and stored in the storage unit 42.

[0024] The control unit 41 reads out the regression equation from the storage unit 42 and identifies the coke content in the upper layer of the charging bed using the regression equation. The control unit 41 controls the coke content adjusting device 23 so that the coke content in the upper layer of the charging bed becomes the identified coke content. This allows the heat index in the upper layer of the charging bed to be adjusted within a range of 30 K·min to 300 K·min.

[0025] Furthermore, when the heat index of the lower layer of the charging bed is set to be within the range of 400 K·min to 1000 K·min, the control unit 41 reads out a regression equation indicating the correspondence relationship between the coke content in the lower layer of the charging bed and the heat index from the storage unit 42, and identifies the coke content in the lower layer of the charging bed using the regression equation. The control unit 41 controls the coke content adjusting device 23 so that the coke content in the lower layer of the charging bed becomes the identified coke content. This allows the heat index of the lower layer of the charging bed to be adjusted to be within the range of 400 K·min to 1000 K·min.

[0026] In the above example, the coke content in the upper and lower layers is adjusted to keep the heat indexes of the upper and lower layers within a predetermined range. However, this is not limiting. For example, the combustibility of the coke may be controlled by adjusting the particle size of the coke charged in the upper and lower layers, thereby keeping the heat indexes of the upper and lower layers within a predetermined range. Furthermore, the moisture content of the sintering raw material charged in each layer may be controlled to control the heat of evaporation of the moisture, thereby keeping the heat indexes of the upper and lower layers within a predetermined range. If the coke content in the upper and lower layers is not adjusted in this way, the sintering machine 20 does not need to have the coke content adjusting device 23.

[0027] Next, we will explain the sintering test that confirmed the relationship between the thermal index of the sintering bed, product yield, and coke consumption rate. A 20 mm thick layer of sintered ore was packed as a bedding layer on the grate in a cylindrical sintering test pot with a diameter of 300 mm and a height of 600 mm. Granulated sintering raw material with an adjusted coke content was then packed on top of this. The amount of added moisture was adjusted so that the moisture content of the granulated material was 7% by mass. The upper layer was the region extending 200 mm below the pot top, and the lower layer was the region extending 380 mm below the pot top to the bedding layer. Granulated sintered material with various coke content was packed into the upper and lower layers, adjusting the thermal index of the upper and lower layers. The blending ratios of the sintering raw material packed into the upper and lower layers in Tests 1 to 5 are shown in Table 1 below.

[0028] [Table 1]

[0029] The sintering raw materials were packed into a cylindrical sintering test pot with the granulated sintering raw material mixture shown in Table 1. Air was drawn in from the bottom of the pot at a suction pressure of 10 kPa, and the surface layer of the sintering raw material was ignited. Thermocouples were inserted into the sintering pot to measure the temperatures at the center of the pot diameter, 100 mm below the top of the pot, and at the center of the pot diameter, 500 mm below the top of the pot, and the thermal indexes of the upper and lower layers were calculated. After sintering was completed, the sinter cake was removed from the cylindrical sintering test pot, divided, and the product yields of the upper and lower layers were evaluated separately. The product yield was evaluated by dropping the upper and lower sinter cakes from a height of 2 m four times, measuring the weight of the sintered cakes that passed through a 5 mm sieve, and then calculating the product yield as the percentage of the weight of the sintered cake that passed through the 5 mm sieve to the weight of the sintered cake before dropping. The evaluation results are shown in Table 2 and Figures 2 and 3.

[0030] [Table 2]

[0031] Figure 2 is a graph showing the relationship between the heat index of the upper layer and product yield. Figure 3 is a graph showing the relationship between the heat index of the lower layer and product yield. In both Figures 2 and 3, the horizontal axis is the heat index (K·min) and the vertical axis is the product yield (mass%).

[0032] As shown in Table 1 and Figure 2, the product yield of the upper layer depends on the thermal index of the upper layer, and to achieve a product yield of 75% by mass or more, the thermal index of the upper layer should be set within the range of 30 K·min to 300 K·min. It is also clear that setting the thermal index of the upper layer within the range of 100 K·min to 200 K·min is more preferable, as it can achieve a product yield of 80% by mass or more.

[0033] Furthermore, as shown in Table 1 and Figure 3, the product yield in the lower layer also depends on the heat index of the lower layer. To achieve a lower layer yield of 85% by mass or more, the heat index of the lower layer must be 400 K·min or higher. On the other hand, the product yield in the lower layer does not exceed 90% by mass, even if the heat index is increased. Therefore, increasing the heat index above 1000 K·min does not lead to further improvement in product yield, but rather increases the coke consumption rate, which is undesirable. Therefore, it is preferable to keep the heat index of the lower layer within the range of 400 K·min to 1000 K·min, and even more preferable to keep it within the range of 600 K·min to 800 K·min.

[0034] Figure 4 is a graph showing the product yield and coke consumption rate for the upper and lower layers in Tests 1 to 5. Tests 1 and 2 are test examples in which the thermal index of the upper layer was in the range of 30 K·min to 300 K·min, and the thermal index of the lower layer was in the range of 400 K·min to 1000 K·min. By keeping the thermal index of the upper and lower layers within the above ranges, the sintering raw materials could be sintered with a thermal index necessary and sufficient for sintering, and it was confirmed that this made it possible to reduce the coke consumption rate to less than 66 kg / ts, thereby confirming that the coke consumption rate in sintered ore production could be reduced.

[0035] Test 4 is a test example in which the thermal index of the upper layer was within the range of 30 K·min to 300 K·min, but the thermal index of the lower layer was outside the range of 400 K·min to 1000 K·min. In Test 4, the thermal index of the lower layer was low, and the product yield in the lower layer decreased, but the product yield in the upper layer, which is prone to decrease, could be improved, and it was confirmed that this made it possible to reduce the coke consumption rate in sintered ore production more than in Tests 3 and 5.

[0036] Tests 3 and 5 are test examples in which the thermal index of the upper layer was outside the range of 30 K·min to 300 K·min, and the thermal index of the lower layer was outside the range of 400 K·min to 1000 K·min. In these tests, the product yield of the upper and lower layers could not be improved, and as a result, it was confirmed that in Tests 3 and 5, the coke consumption rate in sintered ore production could not be reduced. [Explanation of symbols]

[0037] 10. Sintered ore manufacturing equipment 12 Sintering raw materials 14 Granulation water 16 Granulator 20 Sintering machine 22 palettes 23 Coke content adjusting device 24 Cut-off Plate 25 Ignition Furnace 26 Wind Box 30 Crusher 40 Control device 41 Control Unit 42 Storage section

Claims

1. a granulation step of granulating a sintering raw material containing an iron-containing raw material, coke, and a CaO-containing raw material using a granulator to form granulated particles; a charging bed forming step of charging the granulated particles onto an endless moving pallet by a raw material supply device of a sintering machine to form a charging bed of the sintering raw material; a sintering step in which the coke contained in the surface layer of the charging bed is ignited in an ignition furnace provided downstream of the raw material supply device, and the coke is burned by sucking air in the charging bed using a wind box provided below the pallet, thereby turning the charging bed into a sintered cake; a crushing step of crushing the sintered cake to form sinter; and a correspondence relationship between the content of coke in the upper layer of the sintering bed and a heat index is obtained; In the sintered ore manufacturing method, in the sintering layer forming step, the coke content in the upper layer is specified using the correspondence relationship so that the thermal index of the upper layer is within a range of 30 K min or more and 300 K min or less, and the sintered ore is formed so that the coke content in the upper layer becomes the specified coke content.

2. 2. The sintering method according to claim 1, wherein the sintering layer is formed so that the thermal index of the lower layer of the sintering layer is in the range of 400 K·min to 1000 K·min in the sintering layer forming step. The method of producing ore.

3. A correspondence relationship between the coke content and the heat index in the upper layer and the lower layer is obtained in advance, 3. The method for producing sintered ore according to claim 2, wherein in the sintering layer forming step, the coke contents in the upper layer and the lower layer are identified using the correspondence relationship, and the sintering layer is formed so that the coke contents in the upper layer and the lower layer become the identified coke contents.

4. a granulator for granulating sinter raw materials including an iron-containing raw material, coke, and a CaO-containing raw material into granulated particles; a sintering machine comprising: an endless movable pallet; a raw material supplying device for charging the granulated particles onto the pallet to form a charging layer of the sintering raw material; an ignition furnace for igniting the coke contained in the surface layer of the charging layer; and a wind box provided below the pallet for sucking air from within the charging layer, the sintering machine sintering the charging layer to form a sintered cake; a crusher for crushing the sintered cake into sintered ore; a control device for controlling the operations of the granulator, sinterer, and crusher; Equipped with The control device uses a correspondence relationship between the coke content in the upper layer of the charging bed and the thermal index to identify a coke content in the upper layer that will result in a thermal index in the upper layer that is within a range of 30 K min or more and 300 K min or less, and controls the sintering machine so that the coke content in the upper layer becomes the identified coke content.

5. The facility for producing sintered ore according to claim 4, wherein the control device controls the sintering machine so that a heat index in the lower layer of the sintering bed is within a range of 400 K·min to 1000 K·min.

6. 6. The sintered ore manufacturing facility according to claim 5, wherein the control device identifies the coke contents of the upper layer and the lower layer using a correspondence relationship between the coke contents in the upper layer and the lower layer and a heat index, and controls the sintering machine so that the coke contents in the upper layer and the lower layer become the identified coke contents.

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