Sintered ore manufacturing equipment and sintered ore manufacturing method

Abstract

To provide a producing apparatus of a sinter capable of suppressing lowering of a yield of a sinter, by making a difference of a passing air flow in a pallet width direction of a charging layer and a method for producing the sinter.SOLUTION: A producing apparatus of a sinter comprises: a granulator in which a sinter raw material including an iron-containing raw material, a carbon-containing raw material, and a CaO-containing raw material is granulated with a granulator to obtain granulated particles; an endless mobile pallet; a raw material feeding device that charges the granulated particles into the pallet to form a charging layer of a sintered raw material; an ignition furnace that ignites the carbon-containing raw material contained in a surface layer of the charging layer; a sintering machine having a wind box provided below the pallet and sucks air in the charging layer, and sintering the charging layer to form a sintered cake; a crusher in which the sintered cake is crushed into a sintered ore; and a control device that controls the operation of the granulator, the sintering machine, and the crusher, in which the ignition furnace has a plurality of line burners arranged in a pallet width direction, and the controller controls each temperature of the plurality of line burners.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Sintered ore, which is a raw material for blast furnaces, is generally produced using iron-containing raw materials such as iron ore powder, recovered powder in a steelworks, and sintered ore undersize powder, CaO-containing raw materials such as limestone and dolomite, and carbonaceous materials (solid fuel) such as coke fines and anthracite, using a Dwight Lloyd sintering machine (hereinafter referred to as a "sintering machine"), which is an endless traveling sintering machine.

[0003] The sintering raw materials are loaded onto the sinter machine's endless moving pallet, forming a sintering raw material charging layer. The thickness (height) of the sintering raw material is approximately 400 to 800 mm. The carbonaceous material in the sintering layer is then ignited by an ignition furnace installed above the sintering layer. Air is drawn downward through a wind box installed below the pallet, causing the carbonaceous material in the sintering layer to burn one by one. This combustion progresses gradually downward and forward as the pallet moves. The combustion heat generated at this time burns and melts the sintering raw materials, producing a sinter cake. The resulting sinter cake is then crushed in the ore discharge section to become sintered ore.

[0004] In the production of such sintered ore, it is important to suppress uneven sintering and improve the strength and yield of the sintered ore. Patent Document 1 discloses a method for producing sintered ore, in which the height of the top surface of a sintered cake before discharge is measured, the top surface height distribution in the horizontal width direction perpendicular to the pallet traveling direction is determined, and the sintering raw materials are charged so as to reduce the variation in the top surface height distribution. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-182574 Summary of the Invention [Problem to be solved by the invention]

[0006] However, even if the variation in the top surface height distribution is reduced, there is an excess air volume at both ends of the sintering machine's pallet travel direction due to the wall effect, which shortens the time the sintered ore is maintained at a temperature of 1200°C or higher, resulting in a decrease in yield. Furthermore, the excess air volume at the ends of the pallet causes a decrease in the air volume at the center of the pallet travel direction, which results in unsintered areas, further reducing yield.

[0007] The present invention has been made in consideration of these problems, and its object is to provide a sintered ore manufacturing facility and a sintered ore manufacturing method that can reduce the difference in the passing air volume in the width direction of the pallet in the charging bed, thereby suppressing a decrease in the sintered ore yield. [Means for solving the problem]

[0008] The means for solving the above problems are as follows. [1] A sintered ore manufacturing facility comprising: a granulator that granulates sintering raw materials including an iron-containing raw material, a carbon-containing raw material, and a CaO-containing raw material 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 carbon-containing raw material 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 the sintering machine 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 operations of the granulator, sintering machine, and crusher, wherein the ignition furnace has a plurality of line burners lined up in the width direction of the pallet, and the control device controls the temperature of each of the plurality of line burners. [2] The sintered ore manufacturing equipment described in [1], wherein the control device makes the temperature of the line burners at the widthwise ends of the pallet higher than the temperature of the line burners at the widthwise center of the pallet. [3] A method for producing sintered ore, comprising: a granulation step in which sintering raw materials including an iron-containing raw material, a carbon-containing raw material, and a CaO-containing raw material are granulated in a granulator to form granulated particles; a charging bed formation step in which the granulated particles are charged onto an endless moving pallet by a raw material supply device of the sintering machine to form a charging bed of the sintering raw materials; a sintering step in which the carbon-containing raw material 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 carbon-containing raw material is burned by sucking air from the charging bed using a wind box provided below the pallet, thereby forming the charging bed into a sintered cake; and a crushing step in which the sintered cake is crushed to form sintered ore, wherein in the sintering step, ignition is performed in the ignition furnace to change the temperature distribution of the surface layer of the charging bed in the width direction of the pallet. [4] The method for producing sintered ore according to [3], wherein in the sintering step, ignition is performed in the ignition furnace, so that the temperature of the surface layer of the sintering layer at the widthwise end portion of the pallet is higher than the temperature of the surface layer of the sintering layer at the widthwise center portion of the pallet. [Effects of the Invention]

[0009] According to the present invention, the air permeability of the sintering bed in the pallet width direction can be adjusted by controlling the temperature of each of the line burners arranged in the pallet width direction in the ignition furnace. This reduces the difference in the air flow rate in the pallet width direction during sintering of the sintering bed, suppresses uneven sintering, and prevents a decrease in the yield of sintered ore. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing an example of a sintered ore production facility in which the sintered ore production method according to this embodiment can be implemented. [Figure 2] FIG. 2 is a schematic cross-sectional view of the ignition furnace 24 taken along a plane perpendicular to the direction of travel of the pallet 22. As shown in FIG. [Figure 3] FIG. 3 is a graph showing the amount of gas C injected before and after the flow rate of gas C was changed. [Figure 4] FIG. 4 is a graph showing the surface temperature of the sintered bed measured downstream of the ignition furnace 24 before and after changing the flow rate of C gas. [Figure 5] FIG. 5 is a graph showing the difference in oxygen concentration between the end and center portions of the pallet 22 in the width direction. [Figure 6] FIG. 6 is a graph showing the thickness of the residual flame layer before and after changing the gas flow rate of C gas. [Figure 7] FIG. 7 is a graph showing the proportion of particles with a particle size of less than 4 mm, the amount of return ore generated, and the CaO content in the return ore before and after changing the flow rate of gas C. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described below with reference to embodiments. Fig. 1 is a schematic diagram showing an example of a sintered ore production facility in which the 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.

[0012] The granulator 16 granulates the sintering raw material 12, which contains an iron-containing raw material, a carbon-containing raw material, and a 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 carbon-containing raw material is, for example, coke powder or anthracite. The CaO-containing raw material is, for example, quicklime, limestone, or slag.

[0013] 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 cutoff plate 23, an ignition furnace 24, and a wind box 26. The raw material supply device 21 charges the granulated particles 18 into the pallet 22.

[0014] The pallet 22 is an endless movable pallet. When the granulated particles 18 are charged into the pallet 22 from the raw material supply device 21, a charging layer of the sintering raw material 12 is formed inside the pallet 22. The cut-off plate 23 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.

[0015] The ignition furnace 24 has a plurality of line burners arranged in the width direction of the pallet 22. The ignition furnace 24 is provided downstream of the raw material supply device 21, and injects coke oven gas (hereinafter referred to as "C gas") into each of the plurality of line burners, and burns the C gas to ignite the carbon-containing raw materials contained in the surface layer of the charging bed.

[0016] The wind box 26 is installed below the pallet 22 and sucks the air downward from within the sintering bed formed within the pallet 22. When the wind box 26 sucks 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, causing the sintering raw materials 12 in the sintering bed to be sintered. A sintered cake is obtained by sintering the sintering raw materials 12. This process is the sintering step.

[0017] 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.

[0018] The control device 40 is a general-purpose computer such as a workstation or a personal computer, which has a control unit 41 and a memory unit 42. The control unit 41 is, for example, a CPU, 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.

[0019] 2 is a schematic cross-sectional view of the ignition furnace 24 taken along a plane perpendicular to the traveling direction of the pallet 22. The ignition furnace 24 has, for example, five line burners 28a to 28e arranged in the width direction of the pallet 22. C gas carried by a pipe 50 is blown into each of the line burners 28a to 28e. Valves 52a to 52e are provided between the pipe 50 and the line burners 28a to 28e. The control unit 41 adjusts the amount of C gas blown into the line burners 28a to 28e by controlling the apertures of the valves 52a to 52e, thereby controlling the temperature of each of the line burners 28a to 28e.

[0020] The wall effect causes an excess air volume at both widthwise ends of the pallet 22 of the sintering machine 20, shortening the time for which the sinter ore production temperature of 1200°C or higher is maintained, resulting in a decrease in the yield of sintered ore. For this reason, in the method for producing sintered ore according to this embodiment, the temperatures of the line burners 28a to 28e are controlled to make the temperature of the line burners 28a, 28b, 28d, and 28e at both widthwise ends of the pallet 22 higher than the temperature of the line burner 28c at the widthwise center of the pallet 22. This makes it possible to make the surface temperature of the charging layer at both widthwise ends of the pallet 22 higher than the surface temperature of the charging layer at the widthwise center of the pallet 22.

[0021] By increasing the surface temperature of the sintering layer at both widthwise ends of the pallet 22 to be higher than that at the widthwise center of the pallet 22, the sintering layer at both widthwise ends of the pallet 22 is melted only at the surface of the sintering layer at those positions, and the air permeability of the sintering layer at those positions decreases. As a result, the excess air volume due to the wall effect decreases, and the difference in the air volume passing through the pallet 22 in the widthwise direction during sintering of the sintering layer decreases, thereby suppressing uneven sintering and reducing the yield.

[0022] 3 is a graph showing the amount of C gas injected before and after the flow rate of C gas is changed. The control unit 41 opens the valve 52c less than the other valves 52a, 52b, 52d, and 52e. As a result, as shown in FIG. 3, the amount of C gas injected into the line burners 28a, 28b, 28d, and 28e at both ends of the pallet 22 increases, and the amount of C gas injected into the line burner 28c in the center decreases.

[0023] 4 is a graph showing the surface temperature of the sintering bed measured downstream of the ignition furnace 24 before and after changing the flow rate of C gas. The surface temperature of the sintering bed downstream of the ignition furnace 24 is the surface temperature of the sintering bed measured using a thermograph provided at the downstream end of the ignition furnace 24.

[0024] As shown in FIG. 4, by increasing the amount of C gas injected into the line burners 28a, 28b, 28d, and 28e, the surface temperatures of the sintering bed at both widthwise ends of the pallet 22 (north and south in FIG. 4) increased from 514°C and 510°C to 529°C and 538°C, respectively. Meanwhile, by reducing the amount of C gas injected into the line burner 28c, the surface temperature of the sintering bed at the widthwise center of the pallet 22 decreased from 490°C to 280°C. In this way, by increasing the surface temperature of the sintering bed at both widthwise ends of the pallet 22 and decreasing the surface temperature of the sintering bed at the center, the sintering bed at both widthwise ends became more molten than at the widthwise center of the pallet 22, resulting in a decrease in the permeability of the sintering bed at both widthwise ends. This decrease in permeability reduced the excess airflow due to the wall effect and the difference in the airflow across the width of the pallet 22 during sintering.

[0025] Figure 5 is a graph showing the difference in oxygen concentration between the widthwise ends and the center of pallet 22. The oxygen concentrations shown in Figure 5 were measured by inserting a suction pipe from the side of wind box 26, sampling gas from each position in the widthwise direction of pallet 22 using the suction pipe, and measuring the oxygen concentration of the gas.

[0026] 5, it was confirmed that by changing the amount of gas injected into the line burners 28a to 28e and increasing the temperature of the surface layer of the sintering bed at both ends in the width direction of the pallet 22 compared to the center, the difference in the amount of air passing through in the width direction of the pallet 22 during sintering of the sintering bed is reduced, and the difference in oxygen concentration between the ends in the width direction and the center of the pallet 22 is reduced. Specifically, before changing the amount of gas injected, the difference in oxygen concentration between the ends in the width direction and the center of the pallet 22 was 4.29% by volume, whereas after changing the amount of gas injected, the difference in oxygen concentration between the ends in the width direction and the center of the pallet 22 was reduced to 4.10% by volume.

[0027] FIG. 6 is a graph showing the thickness of the residual flame layer before and after changing the gas flow rate of C gas. FIG. 6(a) shows the thickness of the residual flame layer before changing the flow rate of C gas, and FIG. 6(b) shows the thickness of the residual flame layer after changing the flow rate of C gas. In the ore discharge section of the sintering machine 20, just before the sintered cake falls from the pallet 22, a crack occurs from the surface of the sintered cake to the bottom in the pallet width direction. The sintered cake breaks along this crack and falls, exposing the fractured surface. This fractured surface usually contains a portion of the sintered cake that is still red-hot. This red-hot portion is the residual flame layer, and the thickness of this residual flame layer is the residual flame layer thickness. The height difference of this residual flame layer across the width of the pallet 22 correlates with sintering unevenness. As this height difference increases, the sintering unevenness increases and the sintered ore yield decreases. By reducing the height difference of this residual flame layer across the width of the pallet 22, the sintering unevenness of the sintering raw material is improved and the decrease in sintered ore yield is suppressed.

[0028] As shown in Figures 6(a) and 6(b), by changing the amount of C gas injected into the line burners 28a to 28e and increasing the temperature of the surface layer of the sintering bed at both ends in the width direction of the pallet 22 compared to the center, the height difference of the residual flame layer was reduced. Specifically, the height difference of the residual flame layer, which was 160 mm before changing the amount of C gas injected, became 95 mm after changing the amount of C gas injected. From this result, it can be seen that by increasing the temperature of the surface layer of the sintering bed at both ends in the width direction of the pallet 22 compared to the center, the difference in the passing air volume in the width direction of the pallet 22 during sintering the sintering bed is reduced, sintering unevenness is improved, and a decrease in the sinter yield can be suppressed.

[0029] Next, the results of checking the sintered ore yield will be described. Figure 7 is a graph showing the proportion of particles with a particle size of less than 4 mm, the amount of return ore generated, and the CaO content in the return ore before and after changing the amount of C gas injection. Figure 7(a) is a graph showing the mass ratio of sintered cakes with a particle size of less than 4 mm to the total mass of sintered cakes after crushing. Figure 7(b) is a graph showing the amount of return ore generated. Figure 7(c) is a graph showing the CaO content in the return ore.

[0030] As shown in Figure 7(a), by changing the amount of C gas injected into the line burners 28a to 28e and raising the temperature of the surface layer of the sintering bed at both ends in the width direction of the pallet 22 compared to the center, the mass proportion of particles with a particle size of less than 4 mm after crushing was reduced compared to before changing the amount of C gas injected. This result shows that raising the temperature of the surface layer of the sintering bed at both ends in the width direction of the pallet 22 compared to the center improved sintering unevenness and improved the strength of the sintered cake, and it is believed that this improved strength of the sintered cake reduced the mass proportion of particles with a particle size of less than 4 mm after crushing. Note that sintered ore with a particle size of less than 4 mm is sintered ore that was sieved out of the crushed sintered cake using a sieve with 4 mm openings.

[0031] Furthermore, as shown in Figure 7(b), by changing the amount of C gas injected into the line burners 28a to 28e and raising the temperature of the surface layer of the sintering bed at both ends in the width direction of the pallet 22 compared to the center, the amount of return ore generated was reduced. Here, return ore refers to sintered ore with a particle size of less than 5 mm that can be sieved through a 5 mm mesh sieve from the crushed sinter cake, and is reused as a raw material for sintered ore. Therefore, a reduction in the amount of return ore generated means an improvement in the yield of sintered ore, and it was confirmed that the yield of sintered ore can be improved by raising the temperature of the surface layer of the sintering bed at both ends in the width direction of the pallet 22 compared to the center.

[0032] Furthermore, as shown in Figure 7(c), by changing the amount of C gas injected into the line burners 28a to 28e and raising the temperature of the surface layer of the sintering bed at both ends in the width direction of the pallet 22 compared to the center, the CaO content in the return ore was reduced. If the sintering raw materials are unevenly sintered, coke combustion will not progress and the residual CaO in the sintered cake will increase. The reduction in the CaO content in the return ore indicates that the uneven sintering of the sintering raw materials has been improved, coke combustion has progressed, and the residual CaO in the sintered cake has decreased. These results confirm that the uneven sintering of the sintering raw materials can be improved by raising the temperature of the surface layer of the sintering bed at both ends in the width direction of the pallet 22 compared to the center.

[0033] As described above, in the method for producing sintered ore according to this embodiment, the temperature distribution of the surface layer of the sintering bed in the width direction of the pallet 22 is changed by controlling the temperatures of the multiple line burners 28a-28e arranged in the width direction of the pallet 22 and installed in the ignition furnace 24. Specifically, the temperature of the surface layer of the sintering bed in the width direction of the pallet 22 is increased in regions where the permeability of the sintering bed is high, and the temperature of the surface layer of the sintering bed in regions where the permeability of the sintering bed is low is decreased. This allows the surface layer of the sintering bed with high permeability to melt more rapidly than the regions with low permeability, thereby decreasing the permeability of the regions. As a result, the difference in the amount of air passing through the pallet 22 in the width direction during sintering of the sintering bed is reduced, improving uneven sintering of the sintering raw materials and suppressing a decrease in yield.

[0034] 1, the sintered ore production equipment 10 is provided with the control device 40, but this is not limiting. The sintered ore production equipment 10 does not need to be provided with the control device 40. In this case, the opening degree of the valve 52c shown in FIG. 2 may be set narrower in advance than the other valves 52a, 52b, 52d, and 52e.

[0035] In the above embodiment, the temperature of the surface layer of the sintering layer at both ends in the width direction of the pallet 22 is made higher than that of the central portion, but the present invention is not limited to this and may be modified so long as the temperature of the surface layer of the sintering layer at at least one end is made higher than that of the central portion. If the temperature of the surface layer of the sintering layer at at least one end is made higher than that of the central portion, the difference in the amount of air passing through in the width direction of the pallet 22 becomes smaller than when the temperatures of the surface layer of the sintering layer in the width direction of the pallet 22 are the same, so that uneven sintering of the sintering raw materials can be improved and a decrease in yield can be suppressed.

[0036] The sinter ore manufacturing equipment 10 may further include a camera for capturing an image of the ember layer in the ore discharge section of the sinter machine 20. The control unit 41 of the control device 40 may acquire image data of the ember layer captured by the camera, and identify areas of the charging layer with high permeability based on the image data. Specifically, the control unit 41 divides the acquired image data into areas in the width direction of the pallet 22, the number of which is equal to the number of line burners, identifies the height of the upper surface of the ember layer in each area, and identifies areas with a low height of the upper surface of the ember layer as having high permeability.

[0037] The control unit 41 increases the opening of the valve connected to the line burner at the position corresponding to the region identified as having high permeability compared to the other valves, and increases the amount of C gas supplied to the line burner compared to the other regions, thereby raising the temperature of the surface layer of the sintering bed. This allows the melting of the surface layer of the sintering bed in the region where the upper surface height of the residual fire layer is low and the permeability is high to proceed, thereby reducing the permeability of the region and reducing the difference in the ventilation air volume in the width direction of the pallet 22 of the sintering bed. As a result, the difference in the upper surface height of the residual fire layer is reduced, improving the firing unevenness of the sintering raw material and suppressing a decrease in the sintered ore yield. [Explanation of symbols]

[0038] 10. Sintered ore manufacturing equipment 12 Sintering raw materials 14 Granulation water 16 Granulator 18 Granulated particles 20 Sintering machine 21 Raw material supply device 22 palettes 23 Cut-off Plate 24 Ignition Furnace 26 Wind Box 28a~28e Line Burner 30 Crusher 32 Sinter 40 Control device 41 Control Unit 42 Storage section 50 Piping 52a~52e valves

Claims

1. a granulator for granulating a sintering raw material containing an iron-containing raw material, a carbon-containing raw material, and a CaO-containing raw material into granulated particles; a sintering machine comprising: an endless movable pallet; a raw material supplying device that charges the granulated particles onto the pallet to form a charging layer of the sintering raw material; an ignition furnace that ignites the carbon-containing raw material contained in a surface layer of the charging layer; and a wind box that is provided below the pallet and sucks air from within the charging layer, and that sinters 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 ignition furnace has a plurality of line burners arranged in a width direction of the pallet, The control device increases the amount of C gas injected by the line burners at the widthwise ends of the pallet, among the plurality of line burners, compared to the amount of C gas injected by the line burners at the widthwise center of the pallet, thereby increasing the temperature of the line burners at the widthwise ends of the plurality of line burners compared to the temperature of the line burners at the widthwise center, thereby causing the melting of the surface layer of the charging layer at the widthwise ends to proceed more rapidly than the surface layer of the charging layer at the widthwise center.

2. a granulation step of granulating a sintering raw material containing an iron-containing raw material, a carbon-containing raw material, 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 carbon-containing raw material 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 carbon-containing raw material 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 In the sintering step, the amount of C gas injected into the widthwise ends of the pallet in the ignition furnace is made larger than the amount of C gas injected into the widthwise center of the pallet, so that the temperature of the widthwise ends in the ignition furnace is made higher than the temperature of the widthwise center, and melting of the surface layer of the charging layer at the widthwise ends is made more advanced than that of the surface layer of the charging layer at the widthwise center.

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