JP2022090344A - Method for manufacturing sintered ore - Google Patents

Abstract

To provide a new and improved method for manufacturing a sintered ore which predicts both cold strength and reducibility of a sintered ore by a single measurement method, and can manufacture a sintered ore excellent in both the cold strength and the reducibility using the result.MEANS FOR SOLVING THE PROBLEM: A method for manufacturing a sintered ore includes: a step of manufacturing a sintered ore; a step of measuring a surface recess volume of the manufactured sintered ore; and a step of adjusting at least one or more of an amount of an aggregation material to be blended, an amount of a limestone to be blended, and a production rate of a sintered ore so that the measured surface recess volume is within a range of 1,000 to 1,300 μm3/μm2.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a sinter.

The method for producing sinter is as follows. First, a raw material for sinter, which is a raw material for sinter, is blended in a predetermined ratio to prepare a blended raw material, and then granulated together with water. Here, the raw material for sintering is composed of a main raw material, miscellaneous raw materials, auxiliary raw materials necessary for the sintering reaction and component adjustment, carbonaceous materials (solid fuel, coagulant) which are heat sources, and return ore. .. The main raw material is iron ore for sintering such as powder ore and fine powder ore. The miscellaneous raw materials are iron-containing recycled raw materials such as iron-making dust, steel-making dust, and scales. Auxiliary raw materials are, for example, limestone, dolomite, converter slag, serpentinite, silica stone and peridotite. The charcoal material is, for example, coke powder and anthracite.

Then, the granulated material of the compounding raw material is charged into the sintering pallet (strand) of the sintering machine in a layered manner. Then, the solid fuel in the raw material packed bed is ignited from the surface of the raw material packed bed, and suction ventilation is performed in the thickness direction from the top to the bottom of the raw material packed bed. As a result, the combustion zone of the packed bed of the raw material is sequentially shifted to the lower layer side, and the sintering reaction (that is, firing of the compounded raw material) is allowed to proceed. The sinter cake in the sinter pallet after firing is crushed and sized so as to have a predetermined particle size suitable for sinter for a blast furnace. By the above steps, sinter is produced.

The sinter is porous, and its porosity strongly affects the cold strength and reducibility of the sinter. Therefore, various methods for measuring the porosity of the sinter (the porosity including the porosity inside the sinter) have been proposed.

Specifically, as a method for measuring the porosity of the sinter, the mercury method (JIS_M8716), the water method (JIS_K2151), the paraffin method, the plasticin method (iron and steel, 68 (1982), 2215.), The PAC method. (Iron and steel, 93 (1997), 109.) and the like. Since mercury was avoided due to environmental problems, fine pores have been measured by the water method, and coarse pores have been measured by the PAC method.

Japanese Unexamined Patent Publication No. 2018-31735

As mentioned above, the porosity of the sinter strongly affects the cold strength and reducibility of the sinter. More specifically, it is believed that the cold strength of the sinter is dominated by the porosity of the relatively coarse pores, and the reducibility of the sinter is dominated by the porosity of the relatively fine pores. .. The pore diameter (diameter) at this boundary is 0.1 to 0.5 mm. That is, it is said that a pore structure containing many pores of 0.1 mm or less and having few pores of 0.5 mm or more is a preferable pore structure that achieves both cold strength and reducibility of the sinter.

By the way, in order to evaluate the cold strength and reducibility of the sintered ore in a short period of time, the porosity of coarse pores and the porosity of fine pores are measured at the same time (that is, the porosity of a wide range of pores is measured. (Measure) is preferable. However, with the above-mentioned measuring method, the porosity of coarse pores and the porosity of fine pores could not be measured at the same time.

By the way, the surface recess volume is known as a parameter for evaluating the shape of the sinter. Examples of the method for measuring the volume of the surface recess include a method using X-ray CT (iron and steel, 71 (1985), S873) and a method assuming the use of a laser range finder (Patent Document 1). However, these documents do not present any correlation between the volume of the surface recesses of the sinter and the cold strength and reducibility of the sinter.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to predict both the cold strength and the reducibility of the sinter by a single measuring method. It is an object of the present invention to provide a new and improved method for producing a sinter which can produce a sinter having excellent cold strength and reducibility by using the result.

In order to solve the above problems, according to a certain viewpoint of the present invention, the step of producing the sinter, the step of measuring the surface recess volume of the produced sinter, and the measured surface recess volume are Including a step of adjusting at least one of the amount of the setting material, the amount of limestone, and the production rate of the sinter so that the value is in the range of 1000 to 1300 μm ³ / μm ² . A method for producing a sinter is provided.

Here, in the process of measuring the volume of the surface recess, the sintered ore installed on the installation table is imaged by an image pickup device to acquire an image in which the three-dimensional shape of the sintered ore is drawn, and the image is taken from the image. Obtain the cross-sectional shape of the sintered ore, identify the maximum point from the curve showing the cross-sectional shape of the sintered ore, draw a line connecting these maximum points, and then pass through the maximum point and from the line segment. The surface recess integration area is calculated by drawing a straight line tilted by a predetermined angle θ and integrating the surface recess area surrounded by the straight line and the curve existing at the uppermost part, and the surface recess integration area is set as the sintered ore. The volume of the surface recess may be measured by dividing by the projected area of the installation table projected on the table.

Further, the blending amount of the coagulant may be adjusted by adjusting the amount of the coagulant cut out from the raw material hopper of the coagulant.

Further, the blending amount of limestone may be adjusted by adjusting the amount of limestone cut out from the raw material hopper of limestone.

Further, the production rate of the sinter may be adjusted by performing at least one of the treatment for adjusting the firing negative pressure and the treatment for adjusting the layer thickness.

According to the above viewpoint of the present invention, both the cold strength and the reducibility of the sinter are predicted by a single measurement method (that is, the measurement of the surface recess volume), and the result is used as the cold strength and the cold strength. It is possible to produce a sinter having excellent reducibility.

It is a schematic diagram which shows the outline of the sinter manufacturing apparatus which concerns on this embodiment. It is explanatory drawing which shows the outline of the method of obtaining the surface concave volume. It is a graph which shows the correlation of the surface concave volume, the cold strength and the reducing property.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, each raw material used in this embodiment is an aggregate of a large number of particles. Unless otherwise specified, the raw material name of each raw material shall mean an aggregate of particles constituting the raw material. Further, the numerical limitation range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value. Numerical values that indicate "greater than" or "less than" do not fall within the numerical range.

<1. Examination by the present inventor>
First, the study by the present inventor will be described. As the sinter progresses, the cold strength of the sinter increases and the reducibility decreases. On the other hand, the progress of sintering of the sinter is strongly reflected in the unevenness of the surface. That is, as the sintering progresses, the unevenness decreases. From this, the present inventor considered that the volume of the surface recess, which is an index of the unevenness of the surface of the sinter, has a good correspondence with both the cold strength and the reducibility of the sinter.

Therefore, the present inventor investigated the correspondence between the surface recess volume of various sinters (specific measurement method of the surface recess volume will be described later) and SI (cold strength) and RI (reducability). .. As a result, the present inventor confirmed that both SI and RI are good when the surface recess volume is in the range of 1000 to 1300 μm ³ / μm ² (see Examples). The present invention has been made based on such findings. Hereinafter, a method for producing a sinter according to the present embodiment will be described.

<2. Sintered ore manufacturing equipment>
Next, the configuration of the sinter manufacturing apparatus 1 according to the present embodiment will be described with reference to FIG. The manufacturing apparatus 1 is an apparatus for carrying out the method for producing a sinter according to the present embodiment.

The manufacturing apparatus 1 includes a plurality of raw material hoppers 10, conveyors 20a and 20b, a drum mixer 30, a granulated hopper 40, a drum feeder 50, a chute 60, an ignition furnace 80, a pallet 100, and a measuring apparatus 200. And the control device 300 is provided.

The plurality of raw material hoppers 10 are filled with different raw materials for sintering, and a predetermined amount of raw materials for sintering is cut out on the conveyor 20a. Here, the raw material for sintering is composed of a main raw material, miscellaneous raw materials, auxiliary raw materials necessary for the sintering reaction and component adjustment, carbonaceous materials (solid fuel, coagulant) which are heat sources, and return ore. .. The main raw material is iron ore for sintering such as powder ore and fine powder ore. The miscellaneous raw materials are iron-containing recycled raw materials such as iron-making dust, steel-making dust, and scales. Auxiliary raw materials are, for example, limestone, dolomite, converter slag, serpentinite, silica stone and peridotite. The charcoal material is, for example, coke powder and anthracite. The raw material hopper 10a cuts out the coagulant. The amount of the coagulant cut out by the raw material hopper 10a may be controlled by the control device 300. Further, the plurality of raw material hoppers 10 also include a raw material hopper 10 for cutting out limestone, and the amount of limestone cut out from the raw material hopper 10 may also be controlled by the control device 300.

The cut out raw material for sintering is blended on the conveyor 20a to be used as a blending raw material, and is supplied to the drum mixer 30. The drum mixer 30 manufactures granulated products of compounded raw materials by granulating the compounded raw materials together with water. The device for granulating the compounded raw material is not limited to the drum mixer 30, and any device that can granulate the compounded raw material may be used.

The produced granulated product is transported to the granulated product hopper 40 by the conveyor 20b. The granulated material stored in the granulated product hopper 40 is cut out by the drum feeder 50 into the chute 60 and falls on the chute 60. After that, the granulated product is packed in a layer on the pallet 100 to form a raw material packed bed 70.

The packed bed 70 is conveyed to the right in the figure by the pallet 100. When the packed bed 70 reaches the ignition furnace 80, the surface of the packed bed 70 is ignited by the ignition furnace 80. After that, suction ventilation is performed in the thickness direction from the top to the bottom of the packed bed 70 (the negative pressure at this time is also referred to as a firing negative pressure). As a result, the combustion zone of the packed bed 70 is sequentially shifted to the lower layer side, and the sintering reaction (that is, firing of the compounded raw material) is allowed to proceed. The sintered cake 90 on the pallet after firing is crushed and sized by the crusher 110 so as to have a predetermined particle size suitable for sinter. By the above steps, sinter (sinter X) is produced.

The measuring device 200 measures the surface concave volume of the sinter. The specific measurement method will be described later. The control device 300 controls (adjusts), for example, the amount of the coagulant cut out from the raw material hopper 10a based on the measured surface concave volume. Details will be described later.

Next, the processing by the measuring device 200 will be described. The measuring device 200 includes an installation table, an image pickup device (composed of an image pickup unit and a lens), and an arithmetic unit as a hardware configuration. A plurality of sinters (for example, 100 sinters, of course, the number of installations is not limited to 100) are installed on the installation table. Here, it is preferable to install the sinter on the installation table so that a plurality of sinters are not piled up (that is, one sinter is installed in each part of the installation table). ..

The image pickup device is installed on the upper side of the installation table, and images the exposed surface (the surface exposed on the image pickup device side) of a plurality of sinters installed on the installation table. As a result, an image taken by capturing the exposed surfaces of a plurality of sinters is acquired.

More specifically, the image pickup device is based on the focusing method (for example, "High-speed three-dimensional shape measurement by the focusing method" by Mitsuru Ishihara, Hiromi Sasaki, Journal of the Society of Precision Engineering Vo.63, No. 1, 1997). The surface shape of the sinter is sequentially measured. As the image pickup device, for example, an image pickup device having a field of view of 4 mm × 4 mm, a resolution in the horizontal direction of 10 μm, and a resolution in the depth direction of 0.4 μm can be used. Here, the focusing method is to identify the three-dimensional position of the surface of the object by detecting the positional relationship between the lens and the object so that the surface of the object is in focus. Since the method of measuring the three-dimensional shape of the object (here, the sinter) by the focusing method is described in the above non-patent document, detailed description thereof is omitted in the present specification. Therefore, in the above-mentioned captured image, the three-dimensional shape of the exposed surface of the plurality of sinters is drawn. The method for obtaining the three-dimensional shape of the exposed surface of the sinter is not limited to this, and for example, X-ray CT may be used.

The arithmetic unit includes a CPU, ROM, RAM, a communication device, and the like. The CPU reads and executes the program recorded in the ROM. The RAM is a work area by the CPU. The communication device communicates with the control device 300. Specifically, the arithmetic unit measures the surface concave volume based on the captured image captured by the imaging device.

Hereinafter, a method for measuring the volume of the surface recess will be described with reference to FIG. 2. Since the detailed method for measuring the volume of the surface recess is described in Patent Document 1, only an outline thereof will be described here. The surface recess volume is the volume of the depression formed by the surface irregularities of the sinter. The arithmetic unit selects any one sinter X from the captured image and obtains a cross-sectional shape (cross-sectional shape parallel to the thickness direction) of the sinter X as shown in FIG. 2 (a). A curve X1 corresponding to the shape of the exposed surface of the sinter X is drawn on this cross-sectional shape. Then, the arithmetic unit identifies the maximum point A of the curve X1 and draws a plurality of line segments L1 connecting the maximum points A to each other as shown in FIG. 2 (b). Then, the arithmetic unit draws a straight line L2 that passes through the maximum point A and is inclined by an angle θ from the line segment L1 in the sinter X direction. Here, the angle θ may be 5 degrees or more and 15 degrees or less according to Patent Document 1 (Japanese Patent Laid-Open No. 2018-317735).

Then, as shown in FIG. 2C, the arithmetic unit leaves only the straight line L2 existing at the uppermost portion on the cross-sectional shape, and deletes the others. Here, none of the other straight line L2, the line segment L1, and the curve X1 exists above the uppermost straight line L2. In other words, the straight line L2 satisfying such a characteristic becomes the uppermost straight line L2.

Next, in the arithmetic unit, as shown in FIG. 2D, the region surrounded by the straight line L2 and the curve X1 at the uppermost portion is defined as the surface recess region X2, and the area of the surface recess region X2 (there are a plurality of surface recess regions X2). In the case, the sum of the areas of these areas) is calculated. Then, the arithmetic unit repeats the above-mentioned processing in the direction perpendicular to the paper surface of FIG. 2, and calculates the area of the surface recess region X2 for different cross-sectional shapes. Then, the arithmetic unit calculates the surface recess integrated area by integrating (that is, integrating) the calculated area of the surface recess region X2. The arithmetic unit measures the total area of the surface recesses of all the sinter installed on the installation table and calculates the total area of these. On the other hand, the arithmetic unit measures the installation table projection area (projected area when the sinter is projected in the direction perpendicular to the installation table) of all the sinter installed on the installation table, and sums them up. .. Then, the arithmetic unit calculates the surface recess volume (μm ³ / μm ² ) to be evaluated by dividing the total surface recess integrated area by the total projected area of the installation table. The arithmetic unit outputs the measured (calculated) surface recess volume to the control device 300.

The control device 300 includes a CPU, ROM, RAM, a communication device, and the like. The CPU reads and executes the program recorded in the ROM. The RAM is a work area by the CPU. The communication device communicates with the measuring device 200. Specifically, the control device 300 contains the amount of the coagulant, the amount of limestone, and the sinter so that the measured surface recess volume is in the range of 1000 to 1300 μm ³ / μm ² . Adjust at least one of the production rates.

Details will be described in Examples, but when the volume of the surface recess is 1000 to 1300 μm ³ / μm ² , both the cold strength and the reducibility of the sinter become excellent values. The volume of the surface recesses of the sinter decreases as the sinter progresses. That is, as the sinter progresses, the sinter itself becomes stronger and the surface unevenness decreases. Here, since the surface unevenness is a reaction interface, the smaller the surface unevenness, the smaller the reaction interface, and the lower the reducibility. On the other hand, when the sintering of the sinter has not progressed so much, the sinter itself becomes brittle, but the surface unevenness becomes large. When the volume of the surface recess is 1000 to 1300 μm ³ / μm ² , it can be said that the balance between the surface unevenness (that is, reducibility) and the cold strength is excellent. In this way, it is possible to predict the reducibility and cold strength of the sinter by a single parameter of the volume of the surface recess.

Here, the sintering of the sinter is promoted (more advanced) by increasing the blending amount of the coagulant, increasing the blending amount of limestone, or lowering the production rate (t / m ² / day) of the sinter. The volume of the surface recesses of the sinter is reduced. Incidentally, the production rate may be lowered by lowering the firing negative pressure, or the layer thickness of the raw material packed bed 70 may be increased. By either operation, the amount of air passing through the sintered bed is reduced, and the combustion progress rate is reduced accordingly, so that the production rate can be reduced.

Conversely, a decrease in the amount of coagulant, a decrease in the amount of limestone, or an increase in the production rate of the sinter suppresses the sintering of the sinter (it becomes more difficult to proceed), and the sinter The volume of surface recesses increases.

Therefore, the control device 300 takes no action when the volume of the surface recess is 1000 to 1300 μm ³ / μm ² . When the volume of the surface recess is lower than 1000 μm ³ / μm ² , the sinter progresses too much, and the cold strength of the sinter is sufficient, but the reducibility is insufficient. Therefore, the control device 300 performs at least one of the actions of increasing the volume of the surface recess, that is, the reduction of the blending amount of the coagulant, the reduction of the blending amount of limestone, and the increase of the production rate of the sinter. When the volume of the surface recess is higher than 1300 μm ³ / μm ² , the surface unevenness is large (that is, the reaction interface is large), so that the reducibility is sufficient, but the cold strength is insufficient. Therefore, the control device 300 performs at least one of the actions of reducing the volume of the surface recess, that is, increasing the blending amount of the coagulant, increasing the blending amount of limestone, and lowering the production rate of the sinter.

Table 1 shows an example of the volume change of the surface recess due to each action. The value of each raw material in the table is mass%, but the mass% of return ore and coke (a type of coagulant) is the external number (mass% of the total mass of iron ore, limestone, fresh lime, and peridotite). .. The sinter was produced using the production apparatus 1. When measuring the volume of the surface recess, the angle θ shown in FIG. 2 was set to 10 degrees.

With respect to the condition S, the condition T aims at increasing the compounding amount of the coagulant (increasing the dividend), the condition U aims at increasing the compounding amount of limestone, and the condition V aims at decreasing the production rate. Under any of the conditions, the volume of the surface recess was reduced with respect to the condition S. Under condition V, the production rate of sinter was lowered by lowering the firing negative pressure.

Therefore, the surface recess volume of the sinter is controlled to a value within the range of 1000 to 1300 μm ³ / μm ² by the treatment by the measuring device 200 and the control device 300. As a result, both the cold strength and the reducibility of the sinter become excellent values.

<3. Manufacturing method of sinter>
Next, a method for producing sinter using the above-mentioned sinter production apparatus 1 will be described with reference to FIGS. 1 and 2. The method for producing the sinter is as follows: a first step of producing the sinter, a second step of measuring the surface recess volume of the produced sinter, and the measured surface recess volume is 1000 to 1300 μm ³ . A third step of adjusting at least one of the amount of the setting material, the amount of limestone, and the production rate of the sinter so that the value is within the range of / μm ² is included.

(3-1. First step)
The first step is as follows. First, a predetermined amount of the raw material for sintering is cut out on the conveyor 20a from the plurality of raw material hoppers 10. Here, the raw material hopper 10a cuts out the coagulant. The amount of the coagulant cut out by the raw material hopper 10a may be controlled by the control device 300.

The cut out raw material for sintering is blended on the conveyor 20a to be used as a blending raw material, and is supplied to the drum mixer 30. The drum mixer 30 manufactures granulated products of compounded raw materials by granulating the compounded raw materials together with water.

The produced granulated product is transported to the granulated product hopper 40 by the conveyor 20b. The granulated material stored in the granulated product hopper 40 is cut out by the drum feeder 50 into the chute 60 and falls on the chute 60. After that, the granulated product is packed on the pallet 100 on the layer to form a raw material packed bed 70.

The packed bed 70 is conveyed to the right in the figure by the pallet 100. When the packed bed 70 reaches the ignition furnace 80, the surface of the packed bed 70 is ignited by the ignition furnace 80. After that, suction ventilation is performed in the thickness direction from the top to the bottom of the packed bed 70. As a result, the combustion zone of the packed bed 70 is sequentially shifted to the lower layer side, and the sintering reaction is allowed to proceed. The sintered cake 90 on the pallet after firing is crushed and sized by the crusher 110 so as to have a predetermined particle size suitable for sinter. By the above steps, sinter (sinter X) is produced.

(3-2. Second step)
The second step is as follows. First, multiple iron ores are installed on the installation table. Next, the image pickup apparatus images the exposed surface (the surface exposed on the image pickup apparatus side) of the plurality of sinters installed on the installation table. As a result, an image taken by capturing the exposed surfaces of a plurality of sinters is acquired. Here, in the captured image, a three-dimensional shape of the exposed surface of the plurality of sinters is drawn. The details are as described above.

Then, the arithmetic unit measures the surface concave volume based on the captured image captured by the imaging device. The details are as described above, but first, the arithmetic unit selects any one sinter X from the captured image and obtains the cross-sectional shape of the sinter X as shown in FIG. 2 (a). Then, the arithmetic unit identifies the maximum point A of the curve X1 and draws a plurality of line segments L1 connecting the maximum points A to each other as shown in FIG. 2 (b). Then, the arithmetic unit draws a straight line L2 that passes through the maximum point A and is inclined by an angle θ from the line segment L1 in the sinter X direction. Here, the angle θ may be 5 degrees or more and 15 degrees or less according to Patent Document 1 (Japanese Patent Laid-Open No. 2018-317735).

Then, as shown in FIG. 2C, the arithmetic unit leaves only the straight line L2 existing at the uppermost portion on the cross-sectional shape, and deletes the others. Then, as shown in FIG. 2D, the arithmetic unit sets the region surrounded by the straight line L2 and the curve X1 at the uppermost portion as the surface recess region X2, and calculates the area of the surface recess region X2. Then, the arithmetic unit repeats the above-mentioned processing in the direction perpendicular to the paper surface of FIG. 2, and calculates the area of the surface recess region X2 for different cross-sectional shapes. Then, the arithmetic unit calculates the surface recess integrated area by integrating (that is, integrating) the calculated area of the surface recess region X2.

The arithmetic unit measures the total area of the surface recesses of all the sinter installed on the installation table and calculates the total area of these. On the other hand, the arithmetic unit measures the projected area of the sinter installed on the sinter and sums them up. Then, the arithmetic unit calculates the surface recess volume (μm ³ / μm ² ) to be evaluated by dividing the total surface recess integrated area by the total projected area of the installation table. The arithmetic unit outputs the measured (calculated) surface recess volume to the control device 300.

(3-3. Third step)
The third step is as follows. The control device 300 has at least one of the amount of the coagulant, the amount of limestone, and the production rate of the sinter so that the measured surface recess volume is in the range of 1000 to 1300 μm ³ / μm ² . Adjust one or more.

Specifically, the control device 300 takes no action when the volume of the surface recess is 1000 to 1300 μm ³ / μm ² . When the surface recess volume is lower than 1000 μm ³ / μm ² , the control device 300 has an action to increase the surface recess volume, that is, a decrease in the amount of the coagulant, a decrease in the amount of limestone, and the production of sinter. Do at least one of the increased rates. When the surface recess volume is higher than 1300 μm ³ / μm ² , the control device 300 has an action of reducing the surface recess volume, that is, an increase in the amount of the coagulant, an increase in the amount of limestone, and the production of sinter. Do at least one of the reductions in rate.

Therefore, the surface recess volume of the sinter is controlled to a value within the range of 1000 to 1300 μm ³ / μm ² by the treatment by the measuring device 200 and the control device 300. As a result, both the cold strength and the reducibility of the sinter become excellent values. That is, a single measurement method (that is, measurement of the volume of the surface recess) predicts both the cold strength and the reducibility of the sinter, and the results are used to excel both the cold strength and the reducibility. It becomes possible to produce sinter.

Further, the processing by the measuring device 200 (that is, the measurement of the surface recess volume) can be performed faster than each method described in the background technique column (the surface recess volume is output in a short time). Therefore, the processing by the measuring device 200 can be performed online. FIG. 1 shows an aspect of processing performed online. By performing the processing of the measuring device 200 online, it is possible to perform the operation action by the control device 300 without a time lag, and it is expected that the quality will be stabilized. Of course, the processing by the measuring device 200 may be performed offline or on-site (in the same steelworks).

Next, an embodiment of the present embodiment will be described. In this example, the blending amount of the coagulant was changed, and the change in the volume of the surface recess and the accompanying change in the cold strength and reducibility of the sinter were investigated.

<1. Example>
(1-1. Adjustment of compounded raw materials)
Prepare iron ore A to E, limestone, quicklime, peridotite, return ore and coke (a type of coagulant) shown in Table 2 below, and mix them in the blending ratio (mass%) shown in Table 2 below. Raw materials 1 to 3 were used. Here, the compounding ratio of return ore and coke was set to the outer number (mass% of the total mass of iron ore, limestone, quicklime, and peridotite). More specifically, the coke compounding ratio C1 is 4.7 or 5.0% by mass in the outer number, the coke compounding ratio C2 is also 4.4 or 4.7% by mass in the outer number, and the coke compounding ratio C3 is the same. The outside number was 4.5 or 4.8% by mass. That is, since the compounding raw materials 1 to 3 are classified into two types of compounding raw materials having different coke compounding ratios, a total of six types of compounding raw materials are prepared.

(1-2. Outline of sintering experiment equipment)
In this example, a so-called pot test was performed. Table 3 shows an outline of the main sintering experimental equipment used in the pan test.

(1-3. Sintering experiment method)
The pot test (sintering experiment) was performed according to the following procedure. First, the compounding ingredients were mixed with a drum mixer at 25 rpm for 1 minute. Then, 6.8% by mass of water was added to the drum mixer to granulate for 4 minutes. Then, the granulated product was charged from the upper surface of the bedding of the sintering pot to the surface of the sintering pot. Then, the surface of the packed bed of the granulated product was heated by an ignition furnace for 60 [sec] and ignited, and the raw material packed bed was fired at a negative pressure (constant): 11.8 [kPa] in the air box.

The time from the start of ignition to the time when the temperature measured in the air box shows the highest point was regarded as the firing completion time. After the sinter was completed, the sinter cake was taken out from the sinter pan and crushed by dropping the sinter cake from a height of 2 m 5 times to prepare a sinter. The prepared sinter was classified with a sieve having an opening of 5.0 mm. Sintered ore with a particle size larger than 5 mm, specifically, the sinter on the sieve was used as a sintered product.

(1-4. Evaluation of sinter)
Sintered ore products are classified by sieves with a mesh size of 21 mm and 19 mm, and sinters with a particle size larger than 19 mm and 21 mm or less (that is, sinter that remains on a sieve with a mesh size of 19 mm and falls from a mesh size of 21 mm). Got Using these sinters, JIS-RI, which is an index of reducibility, and the volume of surface recesses were evaluated. The surface recess volume was measured using the measuring device 200 described in the above-described embodiment. The angle θ shown in FIG. 2 was set to 10 degrees.

Further, the sinter ore product is classified by a sieve with a mesh size of 20 mm and 10 mm, and the sinter having a particle size larger than 10 mm and 20 mm or less (that is, remaining on a sieve with a mesh size of 10 mm and falling from the mesh size of 20 mm). Ore) was obtained. 10 kg of these sinters were obtained and dropped four times from a height of 2 m. The dropped sinter was classified with a 5 mm sieve, and the ratio of the sinter having a particle size larger than 5 mm (that is, remaining on the sieve with a mesh opening of 5 mm) (mass% with respect to 10 kg) was defined as the cold strength.

<2. Comparative example>
(2-1. Adjustment of compounded raw materials)
In Table 2 above, the coke compounding ratio C1 is 4.4 or 5.3 mass% by mass (mass% of the total mass of iron ore, limestone, raw lime, and rock), and the coke compounding ratio C2 is also external. In preparation, a compounding raw material having a 41% or 5.0% by mass coke compounding ratio C3 of 4.2 or 5.1% by mass in the same external number was prepared. That is, since the compounding raw materials 1 to 3 are classified into two types of compounding raw materials having different coke compounding ratios, a total of six types of compounding raw materials are prepared.

(2-2. Treatment of compounded raw materials)
The compounded raw materials were treated in the same manner as in Examples. The results of Examples and Comparative Examples are shown in FIG. The horizontal axis of FIG. 3 shows the surface recess volume (μm ³ / μm ² ), and the vertical axis shows the cold strength (SI, mass%) or reducibility (RI,%). The point P10 shows the correlation between the volume of the surface recess and the cold intensity, and the graph L10 shows an approximate curve (approximate curve by the least squares method) of the point P10. The point P20 shows the correlation between the volume of the surface recess and the reducibility, and the graph L20 shows an approximate curve (approximate curve by the least squares method) of the point P20.

In the examples, the volume of the surface recesses is 1000 to 1300 μm ³ / μm ² , so that the cold strength (SI) and the reducibility (RI) are both high values, whereas in the comparative example, the surface recesses are high. Since the volume was less than 1000 μm ³ / μm ² or more than 1300 μm ³ / μm ² , either the cold strength (SI) or the reducibility (RI) became a low value.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of the art to which the present invention belongs can come up with various modifications or modifications within the scope of the technical ideas described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

Claims (5)

The process of manufacturing sinter and
The process of measuring the surface recess volume of the produced sinter and
At least one of the amount of the coagulant, the amount of limestone, and the production rate of the sinter so that the measured surface concave volume is in the range of 1000 to 1300 μm ³ / μm ² . A method for producing a sinter, which comprises a step of adjusting the sinter. In the step of measuring the surface recess volume,
By imaging the sinter installed on the installation table with an image pickup device, an captured image in which the three-dimensional shape of the sinter is drawn is acquired.
The cross-sectional shape of the sinter is obtained from the captured image, and the maximum point is specified from the curve showing the cross-sectional shape of the sinter.
A line segment connecting these maximum points is drawn, and a straight line that passes through the maximum point and is tilted by a predetermined angle θ is drawn.
The surface recessed area is calculated by integrating the surface concave area surrounded by the straight line and the curved line existing at the uppermost part.
The sintered ore according to claim 1, wherein the surface recess integrated region is divided by the projected area of the sinter projected onto the sinter to measure the volume of the surface recess. Production method. The method for producing a sinter according to claim 1 or 2, wherein the blending amount of the coagulant is adjusted by adjusting the amount of the coagulant cut out from the raw material hopper of the coagulant. The production of the sinter according to any one of claims 1 to 3, wherein the blending amount of the limestone is adjusted by adjusting the amount of the limestone cut out from the raw material hopper of the limestone. Method. Any one of claims 1 to 4, wherein the production rate of the sinter is adjusted by performing at least one of a process for adjusting the firing negative pressure and a process for adjusting the layer thickness. The method for producing a sinter according to a section.

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