JP7669986B2 - Sintered ore manufacturing method and sintered ore manufacturing equipment - Google Patents

Description

The present invention relates to a method for producing sintered ore, which is a raw material for blast furnaces, and to a production facility for sintered ore.

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

The sintering raw materials are loaded onto the sintering machine's endless moving pallet, forming a charging layer of sintering raw materials. The thickness (height) of the charging layer is around 400 to 800 mm. The carbonaceous material in the charging layer is then ignited by an ignition furnace installed above the charging layer. The carbonaceous material in the charging layer is burned one after another by drawing air downward through a wind box installed under the pallet. 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 sintered cake. The resulting sintered cake is then crushed in the ore discharge section to become sintered ore.

In the sintering machine described above, it is important to improve the yield of sintered ore. As a technology for improving the strength and yield of sintered ore, Patent Document 1 discloses a sintering machine in which a gaseous fuel supply device is provided downstream of the ignition furnace and gaseous fuel is supplied from the upper side of the charging bed. According to Patent Document 1, the gaseous fuel is supplied into the charging bed by sucking air downward using a wind box, and the gaseous fuel is burned, thereby increasing not only the yield of sintered ore in the upper layer of the charging bed, where sintering is likely to be insufficient due to lack of heat, but also the yield of sintered ore in the middle and lower layers of the charging bed.

JP 2010-107154 A

However, there is a problem that even if the sintering machine disclosed in Patent Document 1 is used, the yield of sintered ore may not be improved. The present invention aims to provide a method for manufacturing sintered ore and a manufacturing facility for sintered ore that can improve the yield of sintered ore by using a gas fuel supply device.

The means for solving the above problems are as follows.
[1] 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 by 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 a 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 by an ignition furnace provided downstream of the raw material supply device, gas fuel is supplied to the charging bed from a gas fuel supply device provided downstream of the ignition furnace, and the air in the charging bed is sucked in a wind box provided below the pallet to burn the carbon-containing raw material and form 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 charging bed formation step, the charging bed is formed so that the dry standard charging density of the charging bed is 1.80 dry-ton/m ³ or less.
[2] The method for producing sintered ore according to [1], further comprising a calculation step of calculating a dry basis charging density of the sintering bed.
[3] When the dry base charging density calculated in the calculation step is higher than 1.80 dry-ton / m ³ , the conditions of the charging bed formation step are changed to lower the charging density of the charging bed to be formed. The method for producing sintered ore described in [2].
[4] When the dry standard charge density calculated in the calculation step is higher than 1.80 dry-ton / m ³ , the conditions of the granulation step are changed to narrow the distribution width of the particle size distribution of the granulated particles to be granulated. [2] or [3] The method for producing sintered ore.
[5] The method for producing sintered ore according to [4], wherein the amount of CaO-containing raw material in the sintering raw material is increased.
[6] A granulator that granulates sintering raw materials including an iron-containing raw material, a carbon-containing raw material, and a CaO-containing raw material to form granulated particles, an endless moving pallet, a raw material supplying 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 gas fuel supplying device that is provided downstream of the ignition furnace and supplies gas fuel to the charging layer, and a wind box that is provided below the pallet and sucks air from the charging layer. 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 operation of the granulator, sintering machine, and crusher, wherein the control device controls the sintering machine so that the dry standard charging density of the charging layer is 1.80 dry-ton/m ³ or less.
[7] The sintered ore manufacturing equipment according to [6], wherein the control device calculates a dry base charging density of the charging bed.
[8] When the calculated dry base charging density is higher than 1.80 dry-ton / m ³ , the control device changes the operating conditions of the sintering machine to reduce the charging density of the charging bed. The sintered ore manufacturing equipment described in [7].
[9] When the calculated dry standard loading density is higher than 1.80 dry-ton / m ³ , the control device changes the granulation conditions of the granulator to narrow the distribution width of the particle size distribution of the granulated particles. The sintered ore manufacturing equipment described in [7] or [8].

By implementing the sintered ore manufacturing method according to the present invention, a charging layer with a charging density of 1.80 dry-ton/m3 or less is formed, and the supply of gaseous fuel by the gaseous fuel supply device can improve the yield of sintered ore.

FIG. 1 is a schematic diagram showing a sintered ore production facility in which the sintered ore production method according to the present embodiment can be carried out. FIG. 2 is a schematic cross-sectional view of a sintering test apparatus used in the sintering test. FIG. 3 is a graph showing the relationship between the dry base charging density of the sintered bed and the LNG yield improvement effect. FIG. 4 is a schematic diagram showing the state of granulated particles in the sintering bed. FIG. 5 is a graph showing the relationship between the high temperature holding time of 1200° C. or more and the effect of improving the LNG yield. FIG. 6 is a graph showing the relationship between the dry base charging density and the high temperature holding time at 1200° C. or higher.

Hereinafter, the present invention will be described through an embodiment of the present invention. FIG. 1 is a schematic diagram showing a sintered ore manufacturing facility in which the sintered ore manufacturing method according to this embodiment can be implemented. The sintered ore manufacturing facility 10 includes a granulator 16, a sintering machine 20, a crusher 30, and a control device 40.

The granulator 16 granulates the sintering raw material 12, which contains the iron-containing raw material, the carbon-containing raw material, and the CaO-containing raw material, to produce 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 the sintering machine 20. The iron-containing raw material is, for example, iron ore or dust generated in a steelworks. The carbon-containing raw material is, for example, powdered coke or anthracite. The CaO-containing raw material is, for example, quicklime, limestone, or slag.

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, a gas fuel supply device 25, and a wind box 26. The raw material supply device 21 loads the granulated particles 18 into the pallet 22.

The pallet 22 is an endlessly 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 preset target layer thickness. This process is the charging layer formation step.

The ignition furnace 24 is provided downstream of the raw material supply device 21 and ignites the carbon-containing raw material contained in the surface layer of the charging bed. The gaseous fuel supply device 25 supplies gaseous fuel to the surface side of the charging bed. For example, city gas (LNG) is supplied as the gaseous fuel. The gaseous fuel supplied from the gaseous fuel supply device 25 is not limited to city gas, and any combustible gas selected from blast furnace gas, coke oven gas, blast furnace/coke oven mixed gas, converter gas, natural gas, methane gas, ethane gas, propane gas, shale gas, and mixed gases thereof may be used.

The wind box 26 is provided below the pallet 22 and sucks the air in the charging layer formed in the pallet 22 downward. When the wind box 26 sucks the air in the charging layer downward, the combustion and melting zone in the charging layer moves below the charging layer. In addition, as the air in the charging layer is sucked downward, the gaseous fuel supplied from the gaseous fuel supply device 25 is introduced into the charging layer from the surface layer. As the pallet 22 moves, the combustion and melting zone in the charging layer moves downward, and the sintering raw material 12 in the charging layer is sintered. A sintered cake is obtained by sintering the sintering raw material 12. This process is the sintering step.

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

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

The control unit 41 calculates the dry standard charging density of the charging layer formed in the pallet 22 of the sintering machine 20. The control unit 41 acquires wet standard raw material conveying speed data from the sintering machine 20, and calculates the dry standard raw material conveying speed by subtracting the moisture content of the sintering raw material measured in advance. Furthermore, the control unit 41 calculates the dry standard charging density by dividing the dry standard raw material conveying speed by the machine width of the sintering machine 20, the layer thickness of the charging layer, and the pallet speed. This process is the calculation step. The control unit 41 may display the calculated dry standard charging density.

When the calculated dry standard charging density is higher than 1.80 dry-ton/ ^m3 , the control unit 41 changes the granulation conditions of the granulator 16 and the operating conditions of the sintering machine 20 to lower the charging density of the charging bed so that the dry standard charging density of the charging bed becomes 1.80 dry-ton/m3 or ^less .

When changing the granulation conditions of the granulator 16, the control unit 41 changes the granulation conditions of the granulator 16 so that the distribution width of the particle size distribution of the granulated particles 18 becomes narrower. When the distribution width of the particle size distribution of the granulated particles 18 becomes narrower, the packing density of the granulated particles 18 charged to the pallet 22 becomes lower, and the charging density of the charging bed decreases. The granulation conditions that narrow the distribution width of the particle size distribution of the granulated particles 18 can be obtained by performing granulation experiments in which the rotation speed of the granulator 16, the amount of sintering raw material 12 charged to the granulator 16, the amount of granulation water 14 added, etc. are changed, and the distribution width of the particle size distribution of the granulated particles 18 is confirmed.

Furthermore, the control unit 41 may increase the amount of CaO-containing raw material mixed into the sintering raw material 12. CaO functions as a binder, so it causes ungranulated powder, which is difficult to granulate, to adhere to the granulated particles, reducing the number of fine particles in the particle size distribution. Therefore, when the amount of CaO-containing raw material is increased, the distribution width of the particle size distribution of the granulated particles 18 becomes narrower. Note that in the manufacturing method of sintered ore according to this embodiment, an increase in the amount of CaO-containing raw material is also included in the change of granulation conditions.

When changing the operating conditions of the sintering machine 20, the control unit 41 changes the opening of the charging gate of the raw material supply device 21 and the position of the cutoff plate 23. When changing the opening of the charging gate, the control unit 41 narrows the opening of the charging gate to reduce the amount of granulated particles 18 charged to the pallet 22. By reducing the amount of granulated particles 18 charged, the charging density of the charging bed decreases.

When changing the position of the cutoff plate 23, the control unit 41 raises the position of the cutoff plate 23 to reduce the charging density of the charging bed. The cutoff plate 23 pushes the granulated particles 18 downward to flatten the surface of the charging bed and adjust the thickness of the charging bed to a preset thickness. Therefore, by raising the position of the cutoff plate 23, the amount of granulated particles 18 pushed downward decreases, and the charging density of the charging bed decreases.

Furthermore, if the raw material supply device 21 has a magnetic brake, the control unit 41 may strengthen the magnetic brake to reduce the amount of granulated particles 18 charged to the pallet 22. By reducing the amount of granulated particles 18 charged, the charging density of the charging bed decreases.

In this way, the control unit 41 changes the granulation conditions of the granulator 16 and the operating conditions of the sintering machine 20 to lower the charging density of the charging bed so that the dry standard charging density is 1.80 dry-ton/m3 or ^less . This makes it possible to obtain the effect of improving the yield of sintered ore by supplying gas fuel.

Next, we will explain the sintering test that confirmed the relationship between the dry standard charging density of the charging layer, the yield improvement effect of gas fuel supply, and the high temperature holding time of 1200°C or more. Figure 2 is a cross-sectional schematic diagram of the sintering test equipment used in the sintering test. The sintering test equipment 50 is composed of an ignition hood 51, a sintering pot 52, and a wind box 53. The ignition hood 51 is equipped with an ignition burner 54, which ignites the powdered coke contained in the surface layer of the charging layer 55 formed in the sintering pot 52.

The sintering pot 52 is a cylindrical container with a diameter of 300 mm and a height of 600 mm. Thermocouples 56 are provided in the upper, middle, and lower layers of the sintering pot 52 to measure the temperature at each position, and a grate bar 57 is provided at the bottom end. Granulated particles of sintering raw materials were charged into the sintering pot 52 to form a charging layer 55 with a layer thickness of 600 mm. Granulated particles of sintering raw materials consisting of 89 mass% iron ore, 11 mass% lime, and 4.0 mass% powdered coke were used as the sintering raw materials. A sintering test was conducted in which the charging layer 55 of the sintering raw materials was sintered by sucking with a negative pressure of 10 kPa from the wind box 53 and supplying air containing 0.4 volume% city gas (LNG) from the ignition hood 51 for about 1/3 of the entire sintering time from immediately after the ignition was completed. During the sintering test, the temperatures of the upper, middle, and lower layers of the charging layer 55 were measured using three thermocouples 56. When city gas was supplied, the amount of coke powder equivalent to the calorific value of the city gas was deducted from the sintering raw materials. The yield was calculated by dropping the sintered sample from a height of 2 m four times, sieving the dropped sample through a sieve with 5 mm openings, and dividing the mass of the sample remaining on the sieve by the mass of the sintered sample.

Fig. 3 is a graph showing the relationship between the dry standard charging density of the charging bed and the LNG yield improvement effect. In Fig. 3, the horizontal axis is the dry standard charging density (dry-ton/m ³ ), and the vertical axis is the LNG yield improvement effect (points). Here, the LNG yield improvement effect is a value obtained by subtracting the yield of sintered ore sintered without supplying city gas from the yield of sintered ore sintered with supplying city gas. For example, when the yield of sintered ore is improved from 80.0 mass% to 81.7 mass% by supplying city gas, the LNG yield improvement effect is 1.7 points.

As shown in FIG. 3, the LNG yield improvement effect decreased as the dry base charging density of the charging bed 55 increased. In particular, when the dry base charging density was about 1.80 dry-ton/m ³ , the LNG yield improvement effect tended to disappear. From this result, it was confirmed that the yield improvement effect by supplying gas fuel decreases when the dry base charging density of the charging bed increases. Also, from FIG. 3, if the dry base charging density is set to 1.70 dry-ton/m ³ or less, the LNG yield improvement effect increases, so it is preferable to set the dry base charging density of the charging bed to 1.70 ry-ton/m ³ or less. Furthermore, if the dry base charging density is set to 1.60 dry-ton/m ³ or less, the LNG yield improvement effect can be maximized, so it is more preferable to set the dry base charging density of the charging bed to 1.60 ry-ton/m ³ or less.

Figure 4 is a schematic diagram showing the state of granulated particles in the charging bed. Figure 4(a) shows the state of granulated particles 18 in a charging bed with a low charging density, and Figure 4(b) shows the state of granulated particles 18 in a charging bed with a high charging density. Unlike solid fuels such as powdered coke, gaseous fuels burn only in the voids that serve as the gas passages. When the charging density of the charging bed is low, as shown in Figure 4(a), the combustion space of the gaseous fuel is wide, and the local flow rate of the gaseous fuel in the combustion space is slow. On the other hand, when the charging density of the charging bed is high, as shown in Figure 4(b), the combustion space of the gaseous fuel is narrow, and the local flow rate of the gaseous fuel in the combustion space is fast.

That is, when the charging density of the charging bed is low, the combustion space of the gaseous fuel is wide and the local flow rate of the gaseous fuel is slow, so the gaseous fuel can be burned sufficiently and the time for the combustion heat to be transferred to the granulated particles 18 can be secured relatively long. As a result, the combustion heat of the gaseous fuel is transferred to the granulated particles 18, and the high temperature holding time of 1200°C or more is extended, which is thought to have produced the effect of improving the yield of sintered ore. On the other hand, when the charging density of the charging bed is high, the combustion space of the gaseous fuel is narrow and the local flow rate of the gaseous fuel is fast, so the gaseous fuel cannot be burned sufficiently and the time for the combustion heat to be transferred to the granulated particles cannot be secured. As a result, the combustion heat of the gaseous fuel cannot be transferred to the granulated particles 18, the high temperature holding time of 1200°C or more is not extended, and it is thought that the effect of improving the yield of sintered ore is difficult to produce.

Figure 5 is a graph showing the relationship between high-temperature holding time at 1200°C or higher and the effect of improving LNG yield. In Figure 5, the horizontal axis is Δ high-temperature holding time at 1200°C or higher (sec), and the vertical axis is the effect of improving LNG yield (points). Here, Δ high-temperature holding time at 1200°C or higher indicates the amount of change in high-temperature holding time at 1200°C or higher, with "50" meaning that the high-temperature holding time at 1200°C or higher has been extended by 50 seconds, and "-50" meaning that the high-temperature holding time at 1200°C or higher has been shortened by 50 seconds.

As shown in Figure 5, the effect of improving LNG yield increased as the high temperature holding time above 1200°C increased. This result confirmed that the yield improvement effect of supplying gaseous fuel increases as the high temperature holding time above 1200°C increases.

Fig. 6 is a graph showing the relationship between the dry base charging density and the high-temperature holding time of 1200°C or more. In Fig. 6, the horizontal axis represents the dry base charging density (dry-ton/m ³ ) and the vertical axis represents the high-temperature holding time of Δ1200°C or more (sec).

As shown in Fig. 6, when the dry base charging density was higher than 1.80 dry-ton/ ^m3 , the high temperature holding time of 1200°C or more was hardly extended. On the other hand, it was confirmed that when the dry base charging density was 1.80 dry-ton/ ^m3 or less, the high temperature holding time of 1200°C or more could be extended by supplying gaseous fuel. Since the strength of the sintered cake can be improved if the high temperature holding time of 1200°C or more can be extended, it can be seen that the yield of sintered ore can be improved by setting the dry base charging density of the charging bed to 1.80 dry-ton/ ^m3 or less.

As described above, in the method for producing sintered ore according to this embodiment, the sintering bed is formed so that the dry base charging density of the sintering bed is 1.80 dry-ton/m3 or ^less , and therefore the yield improvement effect of supplying gaseous fuel can be obtained. Furthermore, in the method for producing sintered ore according to this embodiment, the dry base charging density of the sintering bed is calculated. In this way, by calculating the dry base charging density of the sintering bed, it becomes possible to determine whether the yield improvement effect of supplying gaseous fuel can be obtained.

REFERENCE SIGNS LIST 10 Sinter ore manufacturing equipment 12 Sinter raw material 14 Granulation water 16 Granulator 18 Granulated particles 20 Sinter machine 21 Raw material supply device 22 Pallet 23 Cut-off plate 24 Ignition furnace 25 Gaseous fuel supply device 26 Wind box 30 Crusher 32 Sinter ore 40 Control device 41 Control unit 42 Memory unit 50 Sintering test device 51 Ignition hood 52 Sintering pot 53 Wind box 54 Ignition burner 55 Charging bed 56 Thermocouple 57 Grate bar

Claims (9)

A granulation step of granulating a sintering raw material including an iron-containing raw material, a carbon-containing raw material, and a CaO-containing raw material in 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 the sintering machine to form a charging bed of the sintering raw material;
a sintering step of igniting the carbon-containing raw material contained in the surface layer of the charging bed in an ignition furnace provided downstream of the raw material supply device, supplying gaseous fuel to the charging bed from a gaseous fuel supply device provided downstream of the ignition furnace, and burning the carbon-containing raw material by sucking air in the charging bed with a wind box provided below the pallet, thereby making the charging bed into a sintered cake;
A crushing step of crushing the sintered cake into sintered ore;
having
In the sintering bed forming step, the sintering bed is formed so that the dry base charging density of the sintering bed is 1.70 dry-ton/m3 or ^less . The method for producing sintered ore according to claim 1, further comprising a calculation step for calculating the dry standard charging density of the charging layer. When the dry base charge density calculated in the calculation step is higher than 1.70 dry-ton / m ³ ,
The method for producing sintered ore according to claim 2 , further comprising changing conditions of the sintering bed forming step to reduce a charging density of the sintering bed to be formed. When the dry base charge density calculated in the calculation step is higher than 1.70 dry-ton / m ³ ,
The method for producing sintered ore according to claim 2 or 3, further comprising changing conditions in the granulation step to narrow a distribution width of particle size distribution of the granulated particles. The method for producing sintered ore according to claim 4, wherein the amount of CaO-containing raw material in the sintering raw material is increased. a granulator for granulating a sintering raw material including 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 for charging the granulated particles onto the pallet to form a charging layer of the sintering raw material; an ignition furnace for igniting the carbon-containing raw material contained in a surface layer of the charging layer; a gas fuel supplying device provided downstream of the ignition furnace for supplying gas fuel to the charging layer; and a wind box provided below the pallet for sucking air from within the charging layer, and for 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 operation of the granulator, the sinterer, and the crusher;
Equipped with
The control device controls the sintering machine so that the dry standard charging density of the sintering bed is 1.70 dry-ton/m3 or ^less . The sintered ore manufacturing equipment according to claim 6, wherein the control device calculates the dry standard charging density of the charging bed. 8. The sintered ore manufacturing facility according to claim 7, wherein when the calculated dry base charging density is higher than 1.70 dry-ton / m ³ , the control device changes the operating conditions of the sintering machine to reduce the charging density of the charging bed. 9. The sintered ore manufacturing equipment according to claim 7 or 8, wherein when the calculated dry standard charging density is higher than 1.70 dry-ton / m ³ , the control device changes the granulation conditions of the granulator to narrow the distribution width of the particle size distribution of the granulated particles.

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