JP7196758B2 - Sintering dust control method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for controlling dust in sintering exhaust gas discharged from a sintering machine.

Sintered ore is used as the main iron source in blast furnace operation. Sintered ore is produced by mixing iron ore and limestone with a carbonaceous material such as fine coke and firing the mixture in a sintering machine. Exhaust gas (sintering exhaust gas) is generated in the sintering reaction because the heat generated by the combustion of the carbonaceous material and the sucked air is used. The sintering exhaust gas must be treated so that the concentration of pollutants such as dust concentration, sulfur oxide (SO _x ) concentration, nitrogen oxide (NO _x ) concentration, and dioxin concentration satisfies the regulatory or observable values stipulated by laws and agreements. After it is done, it is discharged from the chimney or the like.

One of the environmental problems in sintering is dust in sintering exhaust gas. Various dust reduction methods have been proposed in order to suppress the amount of dust emitted.

In Patent Document 1, by adjusting the sintering combustion end point position so that the exhaust gas temperature in the wind box provided at the bottom of the sintering machine of the downward suction type sintering machine is below a predetermined value, A method for reducing the amount of dust is disclosed. Patent Literature 2 discloses an exhaust gas treatment method for suppressing generation of visible smoke by adjusting the dust concentration and sulfur oxide concentration of the exhaust gas to a predetermined value or less.

JP-A-11-50161 JP 2012-115763 A

Prior to the dust reduction method described above, it is necessary to establish a method for confirming an increase or decrease in the dust concentration of the sintering exhaust gas. In order to confirm an increase or decrease in the dust concentration of the sintering exhaust gas, it is necessary to measure the dust concentration of the sintering exhaust gas discharged from the actual sintering machine.

An object of the present invention is to predict changes in the dust concentration of sintering exhaust gas by a sintering test without measuring the dust concentration of the sintering exhaust gas discharged from an actual sintering machine.

In the sintering dust control method of the present invention, fine particles having a diameter of 2.5 μm or less contained in the sintering exhaust gas by a sintering test for the sintering raw material containing the carbonaceous material used in the production of sintered ore Measure the concentration of In addition, the concentration of fine particles having a diameter of 2.5 μm or less contained in the sintering exhaust gas is measured by a sintering test for the sintering raw material containing the evaluation carbonaceous material to be used for the production of the sintered ore. Then, when the fine particle concentration in the sintering test using the evaluation carbon material is lower than the fine particle concentration in the sintering test using the used carbon material, changing from the used carbon material to the evaluation carbon material will improve the actual sintering performance. It is predicted that the dust concentration of the sintering exhaust gas discharged from the sintering machine will decrease.

On the other hand, when the fine particle concentration in the sintering test using the evaluation carbon material is higher than the fine particle concentration in the sintering test using the used carbon material, the change from the used carbon material to the evaluated carbon material causes the dust concentration to increase. can be expected to increase.

When the fine particle concentration in the sintering test using the evaluation carbon material is lower than the fine particle concentration in the sintering test using the carbon material used, it is determined that the carbon material used can be changed to the evaluation carbon material. can be done. In addition, when the fine particle concentration in the sintering test using the evaluation carbon material is equal to or higher than the fine particle concentration in the sintering test using the used carbon material, it is decided not to change the used carbon material to the evaluation carbon material. can be done.

Based on the fine particle concentrations of the carbonaceous materials used and the plurality of types of evaluation carbonaceous materials, it is possible to rank the dust concentrations. Based on this ranking, it is possible to determine whether or not to change the used carbonaceous material to the evaluation carbonaceous material. Specifically, when the lower the dust concentration, the higher the ranking, when the ranking of the evaluation carbon material is higher than the ranking of the used carbon material, it is determined that the used carbon material can be changed to the evaluated carbon material. be able to. Further, when the lower the dust concentration, the higher the ranking, when the ranking of the evaluation carbon material is lower than the ranking of the used carbon material, it can be determined not to change the used carbon material to the evaluated carbon material.

When the dust concentration measured during the operation of the sintering machine is higher than the control value, it is possible to determine whether or not to change the evaluation carbon material from the used carbon material. As the fine particle concentration, an average value of fine particle concentrations measured from the start to the end of the sintering test can be used. Fine particles contained in the sintering exhaust gas have a particle size of 1 μm or less.

According to the present invention, the dust concentration in the sintering exhaust gas when using the actual sintering raw material in the actual machine, and the sintering raw material (alternative It is possible to easily determine the relationship between the dust concentration in the sintering exhaust gas when the sintering raw material) is used in an actual machine and the level relationship with a test device.

4 is a flowchart showing a sintered dust management method according to the first embodiment; 1 is a schematic diagram of a sintering test apparatus; FIG. It is the schematic of the aerosol measurement part in a sintering test apparatus. 6 is a flow chart showing a method of creating a ranking list of carbonaceous materials in the second embodiment. FIG. 4 is a graph showing the relationship between the elapsed time of firing and the fine particle concentration in a sintering test of sintering raw materials containing carbon materials A and I, respectively. FIG. 4 is a diagram showing the particle size distribution of fine particles in sintering exhaust gas in sintering tests of sintering raw materials containing carbon materials A and I, respectively.

(Definition of fine particles)
The fine particles described in the present embodiment are fine particles in the sintering exhaust gas measured by an aerosol measuring unit described later, and are particles called PM2.5 having a diameter of 2.5 μm or less. As will be described later, the fine particles derived from the carbonaceous material targeted by the present invention were actually 1 μm or less, and thus the particles may have a diameter of 1 μm or less.

(First embodiment)
A sintered dust management method according to the first embodiment will be described with reference to FIG. FIG. 1 is a flowchart showing a sintered dust management method according to the first embodiment. The carbonaceous material described below is the carbonaceous material used for sintering (carbonaceous material for sintering).

<S1: Measurement step>
In the measurement step S1, a sintering raw material (hereinafter referred to as a used sintering raw material) containing a carbonaceous material (hereinafter referred to as a used carbonaceous material) used for producing sintered ore in an actual machine (sintering machine) is measured. A sintering test is performed (S11), and the concentration of fine particles (hereinafter referred to as fine particle concentration) A1 contained in the sintering exhaust gas is measured (S12). In addition, a sintering test is performed using a sintering raw material (hereinafter referred to as an evaluation sintering raw material) containing a carbonaceous material (hereinafter referred to as an evaluation carbonaceous material) that is scheduled to be used in the production of sintered ore in an actual machine ( S13), the fine particle concentration A2 of the sintering exhaust gas is measured (S14). In the sintering tests (S11, S13), a sintering test apparatus, which will be described later, is used under the same test conditions.

Here, with respect to the carbonaceous material used and the carbonaceous material to be evaluated, it is preferable to adjust the blending amount of other carbonaceous materials so that the amount of fixed carbon is equal to the blending amount of the reference carbonaceous material. It is preferable to unify the distribution as well. On the other hand, the fine particle concentrations A1 and A2 may be the fine particle concentrations of the sintering exhaust gas not diluted with air or the like, or the fine particle concentrations of the sintering exhaust gas diluted with air. Further, when the sintering exhaust gas is diluted with air or the like, the dilution ratio can be appropriately determined. However, when measuring the fine particle concentrations A1 and A2, the conditions for diluting the sintering exhaust gas are the same.

The evaluated carbonaceous material is different from the used carbonaceous material. The evaluation sintering raw material is obtained by changing the used carbonaceous material contained in the used sintering raw material to the evaluation carbonaceous material. In other words, raw materials (iron ore, auxiliary raw materials and return ore) other than the evaluated carbonaceous materials included in the evaluated sintering raw materials include raw materials other than the used carbonaceous materials (iron ore, auxiliary raw materials and return ores) ) is used. Here, with respect to the used sintering raw material and the evaluation sintering raw material, the types and compounding amounts (% by mass) of the raw materials other than the carbonaceous material were not changed.

<S2: Prediction step>
In the prediction step S2, based on the fine particle concentrations A1 and A2 measured in the measurement step S1, the dust concentration T1 of the sintering exhaust gas when the sintering raw material used is used in the actual machine, and the carbon material used is changed to the evaluation carbon material. Predict the relationship between the dust concentration T2 of the sintering exhaust gas and the dust concentration T2 when the evaluated sintering raw material is used in an actual machine. The sintering exhaust gas contains fine particles derived from the carbon material, and the concentration of the fine particles affects the dust concentration of the sintering exhaust gas. Therefore, by comparing the fine particle concentrations A1 and A2 as will be described later, it is possible to grasp the level relationship between the dust concentrations T1 and T2.

Specifically, if the fine particle concentration A2 is lower than the fine particle concentration A1 (Yes in S21), by changing the carbon material used to the evaluation carbon material, the dust concentration T2 in the case of using the evaluation sintering raw material in the actual machine is , is predicted to be lower than the dust concentration T1 when the used sintering raw material is used in an actual machine (S22). On the other hand, if the fine particle concentration A2 is equal to or higher than the fine particle concentration A1 (No in S21), by changing the carbon material used to the evaluation carbon material, the dust concentration T2 when the evaluation sintering raw material is used in the actual machine It is predicted that the dust concentration will be equal to or higher than T1 when the coalescing material is used in an actual machine (S23).

<S3: Carbon Material Judgment Step>
In the carbon material determination step S3, it is determined whether or not the used carbon material can be changed to the evaluation carbon material based on the prediction result in the prediction step S2.

Specifically, in the prediction step S2, when it is predicted that the dust concentration T2 will be lower than the dust concentration T1, that is, when the fine particle concentration A2 is lower than the fine particle concentration A1, the used carbon material is changed to the evaluation carbon material. It is determined that it is possible (S31). On the other hand, when the dust concentration T2 is predicted to be equal to or higher than the dust concentration T1, that is, when the fine particle concentration A2 is equal to or higher than the fine particle concentration A1, it is determined not to change the used carbon material to the evaluation carbon material (S32). . In this case, the used carbonaceous material will continue to be used.

As the carbonaceous material contained in the sintering raw material, one kind of carbonaceous material may be used, or a mixture of a plurality of kinds of carbonaceous materials may be used. In general, as the carbonaceous material of the sintering raw material, only coke breeze is used, or a mixture of coke breeze and other carbonaceous materials (anthracite, char) is used.

When changing from using only coke breeze to using a mixture of coke breeze and other carbonaceous materials, comparing the fine particle concentration A1 of coke breeze and the fine particle concentration A2 of the evaluation carbonaceous material (other carbonaceous material), It can be determined that the evaluated carbonaceous material exhibiting a fine particle concentration A2 lower than the fine particle concentration A1 can be used as a substitute for coke breeze. On the other hand, in a mixture of coke fine and other carbonaceous materials (anthracite, char), when trying to change other carbonaceous materials, the fine particle concentration A1 of the used carbonaceous material and the fine particle concentration A2 of the evaluated carbonaceous material are compared, It can be determined that the evaluation carbonaceous material exhibiting a fine particle concentration A2 lower than the concentration A1 can be used as a substitute for the used carbonaceous material. Here, when there are a plurality of evaluation carbonaceous materials showing a fine particle concentration A2 lower than the fine particle concentration A1, any one evaluation carbonaceous material among these evaluation carbonaceous materials can be determined as a substitute for the used carbonaceous material. can.

According to this embodiment, it is possible to predict the high-low relationship of the dust concentrations T1 and T2 in the actual machine only by grasping the high-low relationship of the fine particle concentrations A1 and A2 measured by the sintering test apparatus. Therefore, it is not necessary to measure the dust concentration T2 by using the evaluation sintering raw material in an actual machine, and it is possible to easily predict the level relationship between the dust concentrations T1 and T2. Then, based on the level relationship between the dust concentrations T1 and T2 (that is, the level relationship between the fine particle concentrations A1 and A2), it is possible to determine whether or not to change the used carbon material to the evaluation carbon material.

<Sintering test apparatus used in the measurement step S1>
A sintering test apparatus used in the measurement step S1 will be described with reference to FIGS. 2 and 3. FIG. FIG. 2 is a schematic diagram of a sintering test apparatus. FIG. 3 is a schematic diagram of the aerosol measurement part in the sintering test apparatus.

Referring to FIG. 2 , sintering test apparatus 100 includes sintering pot 1 , suction pipe 3 , blower 5 , exhaust pipe 7 , chimney 9 and aerosol measurement unit 11 . The sintering pot 1 is a cylindrical container for sintering raw materials for sintering, and has an open top end and a fire grate (not shown) at the bottom end. The suction pipe 3 is a pipe for sucking the sintering exhaust gas from the sintering pot 1 during sintering. One end of the suction pipe 3 is connected to the lower end of the sintering pot 1 . A blower 5 is connected to the other end of the suction tube 3 and applies negative pressure to the suction tube 3 . The discharge pipe 7 is a pipe that guides the sintering exhaust gas from the blower 5 to the chimney 9 , and the lower end of the discharge pipe 7 is connected to the blower 5 . The chimney 9 is a cylinder for discharging exhaust gas and is connected to the upper end of the discharge pipe 7 .

The aerosol measurement unit 11 measures the fine particle concentration in the sintering exhaust gas. As shown in FIG. 3, the aerosol measurement unit 11 includes an introduction tube 13, a diluter 15, a sensor 17, an aerosol spectrometer 19, a dryer 21, a filter 23, a flow meter 25, and a suction pump 27.

The introduction pipe 13 is a pipe for sucking the sintering exhaust gas into the aerosol measurement part 11 and is arranged in the flow path of the sintering exhaust gas in the exhaust pipe 7 . The introduction pipe 13 is preferably provided downstream of the blower 5 in the flow path of the sintering exhaust gas. In FIG. 3 the inlet tube 13 is provided within the outlet tube 7 . If the introduction pipe 13 is provided in the suction pipe 3 located upstream of the sintering exhaust gas flow path from the blower 5, the sintering exhaust gas introduced from the introduction pipe 13 is likely to condense due to the moisture generated during sintering. In addition, it becomes difficult to adjust the flow rate of the sintering exhaust gas to be introduced into the aerosol measurement unit 11 due to the negative pressure generated by the blower 5 . Therefore, the introduction pipe 13 is preferably provided downstream of the blower 5 in the flow path of the sintering exhaust gas.

The diluter 15 dilutes the sintering exhaust gas introduced from the introduction pipe 13 by a certain amount with air to reduce the fine particle concentration. It is preferable to use the diluter 15 when the fine particle concentration of the sintering exhaust gas exceeds the measurement limit concentration of the aerosol spectrometer 19 . Air supplied to the diluter 15 is supplied from the compressor 15A. While the air is moving from the compressor 15A to the diluter 15, moisture in the air is removed by the dryer 15B to prevent condensation, the pressure of the air is adjusted by the regulator 15C, and the temperature of the air is adjusted by the heater 15D. Further, when the sintering exhaust gas contains a large amount of moisture, the surroundings of the diluter 15 may be heated with a heater to further prevent dew condensation.

The sensor 17 detects fine particles contained in the sintering exhaust gas. The sensor 17 is arranged in a flow path through which sintering exhaust gas containing fine particles flows and in an optical path through which light for detecting fine particles passes. Aerosol spectrometer 19 measures the particulate concentration. Specifically, the aerosol spectrometer 19 irradiates the flow path of the sintering exhaust gas with light, and measures the particle concentration by utilizing the phenomenon that the irradiated light is scattered by the particles. The dryer 21 removes moisture from the sintering exhaust gas that has passed through the sensor 17 . The filter 23 traps fine particles contained in the sintering exhaust gas that has passed through the dryer 21 . A flow meter 25 measures the flow rate of the sintering exhaust gas that has passed through the filter 23 . The suction pump 27 generates a suction force for introducing the sintering exhaust gas from the exhaust pipe 7 into the aerosol measuring section 11 .

Note that the aerosol measuring unit 11 is not limited to the configuration shown in FIG. 3 as long as it can measure the fine particle concentration of the sintering exhaust gas.

A sintering test using a sintering test apparatus is performed, for example, by the following procedure.

A sintering test is performed using each of the used sintering raw material and the evaluation sintering raw material. The sintering test is conducted in the same test method as the known pot sintering test. The aerosol measurement unit 11 measures the fine particle concentration in the sintering exhaust gas generated during the sintering test.

It is preferable to measure the fine particle concentration continuously. As a result, compared to batch processing in which fine particles in the sintering exhaust gas are captured by a filter or the like and then the fine particle concentration is measured, the fine particle capture rate is high, and the fine particle concentration measurement accuracy can be improved. In addition, it is also possible to measure the temporal change in fine particle concentration from the start to the end of sintering.

The fine particle concentration can be represented, for example, by the number of fine particles per unit volume of the sintering exhaust gas (pieces/ml). Since the fine particle concentration fluctuates (changes over time) during sintering, it is preferable to use an average value obtained by averaging a plurality of fine particle concentrations measured from the start to the end of sintering. Note that, instead of being limited to the average value, for example, it is also possible to focus on the fine particle concentration measured at a predetermined timing during firing, or focus on the highest fine particle concentration during firing.

The sintering exhaust gas contains fine particles derived from iron ore and fine particles derived from carbon material. It tends to be smaller, and the maximum particle size is 1 μm or less.

(Second embodiment)
A sintered dust control method according to the second embodiment will be described. In this embodiment, the carbonaceous materials used and the plurality of types of evaluation carbonaceous materials are ranked according to the level of dust concentration in the sintering exhaust gas. FIG. 4 is a flow chart showing a method of creating a ranking list of evaluated carbonaceous materials.

First, a sintering test is performed using the used sintering raw material (S11), and the fine particle concentration A1 of the sintering exhaust gas is measured (S12). Further, a sintering test is performed using a plurality of types of evaluation sintering raw materials containing different evaluation carbonaceous materials (S15), and the fine particle concentration A2 of the sintering exhaust gas is measured for each evaluation sintering raw material (S16). Here, the sintering test is performed using the sintering test apparatus described above. In addition, in a plurality of evaluation sintering raw materials, the types and blending amounts of raw materials (sintered ore, auxiliary raw materials and return ore) other than the evaluation carbonaceous materials are not changed.

Next, based on the measured fine particle concentrations A1 and A2, a ranking list of the used carbonaceous materials and a plurality of evaluation carbonaceous materials is created (S4). The order here is the order related to the dust concentration of the sintering exhaust gas. As described above, the concentration of fine particles derived from the carbon material affects the dust concentration of the sintering exhaust gas, and the higher the fine particle concentration, the higher the dust concentration. Therefore, a ranking table can be created by ranking the particles in descending order of the particle concentrations A1 and A2, or by ranking them in descending order of the particle concentrations A1 and A2. The method of ranking the evaluation carbonaceous materials will be specifically described below.

Assume that the particle concentration of the sintering raw material SM1 is Aa and the particle concentration of the sintering raw material SM2 is Ab as a result of measuring the particle concentration of the two sintering raw materials SM1 and SM2. Here, the sintering raw materials SM1 and SM2 include a combination of a used sintering raw material and an evaluated sintering raw material, and a combination of two evaluated sintering raw materials.

When the fine particle concentration Aa is lower than the fine particle concentration Ab, the dust concentration Ta of the sintering exhaust gas when using the sintering raw material SM1 in the actual machine is higher than the dust concentration Ta of the sintering exhaust gas when using the sintering raw material SM2 in the actual machine. It can be predicted that it will be lower than the concentration Tb. In this case, for example, the rank of the carbon material contained in the sintering raw material SM1 is set higher than the rank of the carbon material contained in the sintering raw material SM2. In other words, the rank of the carbonaceous material contained in the sintering raw material SM2 is made lower than the rank of the carbonaceous material contained in the sintering raw material SM1. Here, it means that the higher the rank, the lower the dust concentration of the sintering exhaust gas. Note that the higher the dust concentration of the sintering exhaust gas, the higher the rank.

By ranking as described above, it is possible to create a ranking table according to the dust concentration for the carbonaceous materials used and the plurality of types of evaluation carbonaceous materials. Table 1 below shows an example of a ranking table of carbon materials.

In the ranking table shown in Table 1, the higher the ranking, the smaller the number indicating the ranking, and the higher the ranking, the lower the dust concentration of the sintering exhaust gas. Regarding the carbon materials A to J and the coke fine shown in Table 1, any one of the carbon materials is the used carbon material, and the other carbon materials are the evaluation carbon materials. The fine particle concentrations shown in Table 1 above are values measured in Examples described later. In Table 1 above, for example, the fine particle concentration of carbon material D (575 [particles/ml]) is lower than the fine particle concentration of carbon material B (37603 [particles/ml]). It ranks higher than D.

The method of ranking the carbonaceous materials is not limited to the method described above. In the above example (Table 1 above), the 11 types of carbonaceous materials are ranked from 1 to 11 in descending order of fine particle concentration, and the number of ranks is the same as the number of carbonaceous materials. On the other hand, it is possible to predetermine a plurality of concentration ranges for the concentration of fine particles, and rank the concentration ranges for each concentration range. A specific description will be given below.

Table 2 below shows a ranking table (one example) according to the concentration range of fine particle concentration for carbon materials A to J and coke breeze. The carbon materials A to J and coke breeze are the same as the carbon materials A to J and coke breeze shown in Table 1 above.

In Table 2 above, the ranking "R1" is the ranking when the fine particle concentration is less than 10000 [particles/ml], and the ranking "R2" is the ranking when the fine particle concentration is 10000 [particles/ml] or more and 20000 [particles/ml]. ml]. The ranking "R3" is the ranking when the particle concentration is 20000 [particles/ml] or more and less than 30000 [particles/ml], and the ranking "R4" is the ranking when the particle concentration is 30000 [particles/ml] or more and 40000 [particles/ml] or more. It is the rank when it is less than [number/ml]. The rank “R5” is the rank when the fine particle concentration is 40000 [particles/ml] or more. Here, the rank increases in the order of rank R5 to rank R1, meaning that the higher the rank, the lower the dust concentration of the sintering exhaust gas.

When the rankings R1 to R5 are determined as described above, a plurality of different carbonaceous materials may have the same ranking depending on the fine particle concentration. It should be noted that the concentration range of the fine particle concentration that defines each of the orders R1 to R5 is not limited to the concentration range described in Table 2 above, and can be determined as appropriate. Further, when the concentration range of the fine particle concentration is defined by the upper limit value and the lower limit value, the difference between the upper limit value and the lower limit value may be the same or different in all orders. Furthermore, the number of ranks can also be determined as appropriate.

As described above, if a ranking list is prepared for the used carbonaceous materials and multiple types of evaluation carbonaceous materials, this ranking table can be used as a decision index when trying to replace the used carbonaceous materials with the evaluated carbonaceous materials. can. Specifically, by comparing the rank of the used carbonaceous materials with the rank of the evaluated carbonaceous materials, it is possible to determine the evaluated carbonaceous materials that can be used in place of the used carbonaceous materials.

For example, in the ranking table (Table 1 or Table 2 above) in which the lower the dust concentration of the sintering exhaust gas, the higher the ranking, the evaluation carbonaceous materials showing higher ranking than the used carbonaceous materials are used. Determine if it can be used as an alternative. On the other hand, in the ranking table in which the higher the dust concentration of the sintering flue gas, the higher the ranking, it is possible to use the evaluated carbonaceous materials that are ranked lower than the ranking of the used carbonaceous materials as a substitute for the used carbonaceous materials. to decide.

In the ranking table shown in Table 1, for example, when the carbonaceous material used is carbonaceous material C (fine particle concentration A1 is 17981 [particles/ml]), carbonaceous materials D, E, I, and J ranked 1 to 5 Alternatively, it is determined that coke breeze can be used as a substitute for the carbonaceous materials used. Further, in the ranking table shown in Table 2 above, for example, when the carbon material used is carbon material G (particle concentration A1 is 27010 [particles/ml]), ranks R1 and R2 higher than rank R3 of the carbon material used are set. It is judged that the evaluation carbon materials C to E, I, J or coke fine shown can be used as substitutes for the carbon materials used.

The timing of changing the carbon material used can be determined as appropriate. For example, in the operation of an actual machine, the dust concentration of the sintering exhaust gas is measured, and when the dust concentration (measured value) is higher than the control value, the carbonaceous material used can be changed. Here, the control value is usually a control value that is an operation target from the viewpoint of suppressing the generation of visible smoke, and is set lower than the control value of dust concentration predetermined based on laws and the like.

When determining a carbonaceous material to substitute for the carbonaceous material to be used, for example, changes in the dust concentration (measured value) and the difference between the dust concentration (measured value) and the control value can be considered. When considering changes in the dust concentration (measured value), it may be possible to grasp that the dust concentration (measured value) has temporarily become higher than the control value. In this case, it is preferable to use a carbonaceous material with a higher rank than the used carbonaceous material, but it may be determined that it is not necessary to use a carbonaceous material with a higher rank than the used carbonaceous material. In addition, when considering the difference between the dust concentration (measured value) and the control value, the larger the difference, the higher the ranking of the carbonaceous materials used.

EXAMPLES The present invention will be specifically described below based on examples.

(Example 1)
A sintering test was performed on each of a plurality of sintering raw materials differing only in carbon material, and the fine particle concentration of the sintering exhaust gas was measured. First, sintering raw materials containing carbon materials A to J shown in Table 3 below were prepared. Table 3 below shows the industrial analysis values and elemental analysis values of each carbon material A to J and coke fine.

In Table 3 above, industrial analysis values are the results of analysis based on JIS M8820. The elemental analysis values C, H, and N are the results of analysis based on JIS M8819 using CHN628 manufactured by LECO, and the elemental analysis value Total-S is the result of analysis based on JIS M8814. is.

Table 4 below shows the compounding ratio (% by mass) of each raw material component in the raw material for sintering. The blending ratio (% by mass) of the return ore and the carbon material is the blending ratio (outside number) when the total of the iron ore and the auxiliary raw material is 100% by mass. Regarding the blending ratio (% by mass) of the carbonaceous material shown in Table 4 below, each carbonaceous material was adjusted so that the amount of fixed carbon on a dry basis was equal to the coke fine having a blending ratio of 4.5% by mass. The compounding amounts of A to J were adjusted.

The coke fines and carbonaceous materials A to J were adjusted to the particle size distribution shown in Table 5 below by pulverization and classification. If the particle size distribution of the carbonaceous material is different, it is necessary to change the operating conditions other than the type of carbonaceous material. uniform distribution.

In Table 5 above, "less than 0.25" means the ratio (% by mass) of the carbonaceous material that passed through a sieve with an opening of 0.25 mm to the total amount of each carbonaceous material A to J or coke breeze. means. “0.25 or more and less than 0.5” means that the total amount of each carbon material A to J or coke breeze does not pass through a sieve with an opening of 0.25 mm, but a sieve with an opening of 0.5 mm It means the ratio (% by mass) occupied by passing carbonaceous materials. “0.5 or more and less than 1” means that the total amount of each carbon material A to J or coke breeze does not pass through a sieve with an opening of 0.5 mm, but does not pass through a sieve with an opening of 1 mm. means the ratio (% by mass) occupied by. "1 or more and less than 3" means the ratio of carbon materials that do not pass through a sieve with a mesh size of 1 mm but pass through a sieve with a mesh size of 3 mm to the total amount of each carbon material A to J or coke breeze ( mass %). "3 or more and less than 5" means the ratio of carbon materials that do not pass through a sieve with a mesh size of 3 mm but pass through a sieve with a mesh size of 5 mm to the total amount of each carbon material A to J or coke breeze ( mass %).

Prior to conducting sintering tests, sintering raw materials were prepared as follows. First, about 70 kg of sintering raw material was charged into a drum mixer with a diameter of 1000 mm rotating at 23 rpm and mixed for 1 minute. The final sintered raw material was made by adding 7.5% by weight of water to the total weight of the mixed sintered raw material in a drum mixer and granulating for an additional 4 minutes.

A sintering pot 1 (see FIG. 2) having a diameter of 300 mm and a depth of 600 mm was laid with 1.5 kg of bedding. 65 kg of sintering raw material was charged onto the bedding ore to form a sintering raw material layer in the sintering pot 1 . By operating the blower 5 and sucking air from below the sintering pot 1 with a negative pressure (1530 kPa), an air flow directed downward from above was generated in the sintering raw material layer. After that, the surface of the sintering raw material layer was heated with a gas burner of an ignition device (not shown) for 90 seconds to ignite the sintering raw material layer, and sintering proceeded.

During firing, the aerosol measurement unit 11 was used to sequentially measure the fine particle concentration in the discharge pipe 7 (see FIG. 3). As the aerosol spectrometer 19 of the aerosol measurement unit 11, an aerosol spectrometer (Promo 2000) manufactured by PALAS was used. As the sensor 17, a sensor (2070H) manufactured by PALAS was used.

A specific procedure for measuring the fine particle concentration is as follows.

First, the sintering exhaust gas in the discharge pipe 7 was taken into the aerosol measurement unit 11 by sucking with the suction pump 27 . Further, the air for dilution heated to 110° C. and dried through a compressor 15A, a dryer 15B, a regulator 15C and a heater 15D was sent to a diluter 15 (DI-1000 manufactured by DEKATI). After mixing the sintering exhaust gas and the air for dilution in the diluter 15, the mixed gas is led to the sensor 17, and the fine particles floating on the optical path are detected by the sensor 17, and the particle size and the fine particle concentration [pieces/ ml] was measured. Further, the diluter 15 was kept at 120° C. by a mantle heater installed outside the diluter 15 .

The mixing ratio of the sintering exhaust gas and the dilution air was set to 1:7 in volume ratio (sintering exhaust gas: dilution air, dilution ratio 8 times). The fine particle concentration (measured value) shown below is the fine particle concentration of the sintering exhaust gas diluted 8 times with dilution air, and is the average value of the fine particle concentrations measured from the start to the end of sintering. . The flow rate of the sintering exhaust gas led to the sensor 17 was set to 5 [l/min] according to the specifications of the sensor 17 .

Table 6 below shows the fine particle concentration (average value) of each carbon material A to J and coke breeze, the volatile content of each carbon material A to J and coke breeze, and the sintering exhaust gas sampled from the same position as the introduction pipe 13. , the results of measuring the dust concentration based on the method for measuring dust concentration in exhaust gas (JIS Z8808) are shown.

As can be seen from Table 6 above, no correlation was observed between fine particle concentration (average value), volatile matter and dust concentration. In particular, carbonaceous materials (char) F to J all showed substantially the same volatile content, but there was a large difference in the concentration of fine particles. Among the carbonaceous materials (char) F to J, the carbonaceous materials F, G, and H, which have a relatively high fine particle concentration, were not sufficiently dry-distilled during the production of the char. It is presumed that some components with higher volatile content than the analysis value, which is the average value, remained.

According to Table 6 above, it is difficult to grasp the dust concentration of the sintering exhaust gas even if attention is focused on the volatile matter or dust concentration of the carbon materials A to J and the coke fine. A direct causal relationship between the fine particle concentration and the dust concentration in the sintering exhaust gas is recognized, so focusing on the fine particle concentration makes it easier to grasp the dust concentration in the sintering exhaust gas.

On the other hand, for carbon materials A and I having the same volatile content, the fine particle concentration of the sintering exhaust gas (8-fold dilution) was continuously measured from the start to the end of firing. This measurement result is shown in FIG. In FIG. 5, the horizontal axis indicates the elapsed time [sec] of baking, and the vertical axis indicates the fine particle concentration [particles/ml].

As shown in FIG. 5, the concentration of fine particles was detected at the start of the sintering pot test (start of sintering), and the concentration of fine particles increased as the sintering progressed. Further, the fine particle concentration was no longer detected after the firing was completed. This tendency was the same for the carbon materials A and I, although there was a difference in the absolute value of the fine particle concentration. Therefore, when comparing the fine particle concentrations of two carbonaceous materials as described above, the average value of the fine particle concentrations from the start to the end of firing can be used as the fine particle concentration.

On the other hand, for carbon materials A and I, the particle size distribution shown in FIG. 6 was obtained based on the particle size of the fine particles measured by the sensor 17. In FIG. 6, the horizontal axis indicates the particle size [μm], and the vertical axis indicates the number of particles [pieces] of the fine particles. As can be seen from FIG. 6, most of the fine particles contained in the sintering exhaust gas had a particle size (diameter) of 1 μm or less.

(Example 2)
Based on the measurement results of the fine particle concentrations of the carbon materials A to J and the coke fine in Example 1 (Table 1 above), it was determined whether or not the carbon material contained in the sintered carbon material used could be changed. Four examples are described below.

<Example 1>
In the case where only coke breeze is used as the carbonaceous material, it was planned to replace 50% by mass of this coke breeze with carbonaceous material D (anthracite). According to Table 6 above, the fine particle concentration of carbon material D (575 [particles/ml]) is lower than the fine particle concentration of coke breeze (1132 [particles/ml]). Therefore, it is predicted that the dust concentration in the sintering exhaust gas when half of the coke breeze is changed to the carbon material D is lower than the dust concentration in the sintering exhaust gas when only coke breeze is used. Therefore, it was determined that half of the coke breeze could be changed to carbonaceous material D.

<Example 2>
In the case where coke fine and carbon material E (anthracite) are blended and used as the carbon material to be used at a rate of 50% by mass each, it was planned to change the carbon material E to carbon material C (anthracite). According to Table 6 above, the fine particle concentration of carbon material C (17981 [particles/ml]) is higher than the fine particle concentration of carbon material E (466 [particles/ml]). Therefore, it is predicted that the dust concentration of the sintering exhaust gas when the carbon material E is changed to the carbon material C will be higher than the dust concentration of the sintering exhaust gas when the carbon material E is used. Therefore, it was determined that the carbon material E could not be changed to the carbon material C.

<Example 3>
In the case where coke fine and carbon material J (char) are blended and used as the carbon material to be used at 50% by mass each, it was planned to change the carbon material J to carbon material F (char). According to Table 6 above, the fine particle concentration of carbon material F (41037 [particles/ml]) is higher than the fine particle concentration of carbon material J (1867 [particles/ml]). Therefore, it is predicted that the dust concentration in the sintering exhaust gas when the carbon material J is changed to the carbon material F is higher than the dust concentration in the sintering exhaust gas when the carbon material J is used. Therefore, it was determined that the carbon material J could not be changed to the carbon material F.

<Example 4>
In the case where coke fine and carbon material A (anthracite) are blended and used as the carbon material to be used at a rate of 50% by mass each, it was planned to change the carbon material A to carbon material G (char). According to Table 6 above, the fine particle concentration of carbon material G (27010 [particles/ml]) is lower than the fine particle concentration of carbon material A (34819 [particles/ml]). Therefore, it is predicted that the dust concentration of the sintering exhaust gas when the carbon material A is changed to the carbon material G is lower than the dust concentration of the sintering exhaust gas when the carbon material A is used. Therefore, it was determined that the carbon material A can be changed to the carbon material G.

In Examples 1 to 4 described above, it is determined whether or not the carbonaceous material can be changed by comparing the fine particle concentrations of the carbonaceous materials, but the present invention is not limited to this. That is, as described in the second embodiment, a ranking list of evaluation carbonaceous materials (Table 1 or Table 2 above) is created, and based on this ranking table, it is determined whether or not the carbonaceous material can be changed. can do.

1: sintering pot, 3: suction pipe, 5: blower 5, 7: discharge pipe, 9: chimney,
11: aerosol measurement unit, 13: introduction tube, 15: diluter, 17: sensor,
19: aerosol spectrometer, 21: dryer, 23: filter 25: flow meter, 27: suction pump

Claims (10)

Measure the concentration of fine particles having a diameter of 2.5 μm or less contained in the sintering exhaust gas by a sintering test for the sintering raw material containing the carbonaceous material used in the production of sintered ore,
Measure the concentration of fine particles having a diameter of 2.5 μm or less contained in the sintering exhaust gas by a sintering test for the sintering raw material containing the evaluation carbonaceous material scheduled to be used for the production of sintered ore,
When the fine particle concentration in the sintering test using the evaluation carbon material is lower than the fine particle concentration in the sintering test using the used carbon material, changing the used carbon material to the evaluation carbon material reduces the A sintering dust management method characterized by predicting that the dust concentration of sintering exhaust gas discharged from a sintering machine will decrease. When the fine particle concentration in the sintering test using the evaluation carbon material is higher than the fine particle concentration in the sintering test using the used carbon material, the change from the used carbon material to the evaluated carbon material causes the 2. The sintering dust management method according to claim 1, wherein an increase in dust concentration is predicted. When the fine particle concentration in the sintering test using the evaluation carbon material is lower than the fine particle concentration in the sintering test using the used carbon material, the used carbon material can be changed to the evaluation carbon material. 3. The sintering dust management method according to claim 1 or 2, wherein the determination is made. When the fine particle concentration in the sintering test using the evaluation carbon material is equal to or higher than the fine particle concentration in the sintering test using the used carbon material, it is determined not to change the used carbon material to the evaluation carbon material. The sintered dust control method according to claim 2, characterized in that: Based on the fine particle concentrations of the carbonaceous materials used and the plurality of types of the carbonaceous materials to be evaluated, rank the levels of the dust concentrations,
3. The method for managing sintered dust according to claim 1, wherein whether or not to change the used carbonaceous material to the evaluation carbonaceous material is determined based on the ranking. When the lower the dust concentration, the higher the ranking,
6. The firing method according to claim 5, wherein when the ranking of the evaluated carbonaceous material is higher than the ranking of the used carbonaceous material, it is determined that the used carbonaceous material can be changed to the evaluated carbonaceous material. Soot control method. When the lower the dust concentration, the higher the ranking,
6. The sintered dust according to claim 5, wherein when the ranking of the evaluated carbonaceous material is lower than the ranking of the used carbonaceous material, it is determined not to change the used carbonaceous material to the evaluated carbonaceous material. Management method. 8. Any one of claims 3 to 7, wherein when the dust concentration measured during operation of the sintering machine is higher than a control value, it is determined whether or not to change the evaluation carbonaceous material from the used carbonaceous material. 1. A sintered dust management method according to one. The sintered dust according to any one of claims 1 to 8, wherein the fine particle concentration is an average value of fine particle concentrations measured from the start to the end of the sintering test. Management method. The sintered dust control method according to any one of claims 1 to 9, wherein the fine particles have a diameter of 1 µm or less.

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