Method for estimating strength of coke after reaction of blended coal, method for producing coke of blended coal, method for operating a coke oven, and method for controlling blending ratio of single coal

Abstract

A method for quickly estimating the post-reaction strength of blended coal coke is provided. A method for estimating the post-reaction strength (CSR) of a blended coal coke, comprising: 2 A method for estimating the post-reaction strength of a coal blended coke, comprising the steps of: measuring the TG reaction rate of a single coal coke, estimating the TG reaction rate of a coal blended coke from a weighted average of the TG reaction rates of the single coal cokes measured, where the TG reaction rate is the rate of weight loss when the coke is held in an atmosphere in a specified temperature range for a specified time; estimating a reaction rate (CRI) of the coal blended coke from the TG reaction rate of the coal blended coke estimated in the step; and estimating a post-reaction strength (CSR) of the coal blended coke from the reaction rate (CRI) of the coal blended coke estimated in the step and a strength (DI) of the coal blended coke.

Description

[Technical field]

[0001] The present invention relates to a method for quickly estimating the post-reaction strength of blended coal coke. [Background technology]

[0002] Conventionally, in addition to iron ore and other raw materials for iron production, coke is charged as an auxiliary raw material into a blast furnace. In order to produce coke of a desired quality, multiple types of coal with different qualities are mixed to adjust the quality of the blended coal, which is then crushed and carbonized in a coke oven. Each type (brand) of coal before mixing is called single coal.

[0003] Since the quality of coke has a significant impact on the operation of a blast furnace, it is necessary to produce a stable, high-quality coke. In particular, since coke plays a role in ensuring ventilation inside the blast furnace, it is important to produce high-strength coke in order to suppress the generation of fines that impede ventilation inside the furnace. Coke receives different impacts depending on the part inside the blast furnace. Therefore, coke strength (Drum Index: DI) and coke strength after CO2 reaction (Coke Strength after CO2 Reaction: CSR) are used as management indicators of coke strength.

[0004] In particular, the coke reacted strength (CSR) is used as a strength index that expresses the deterioration of coke due to hot reaction with CO2 in a blast furnace. The measurement method of CSR is specified in ISO18894 and is defined as follows. 200g of coke adjusted to a particle size of 20±1mm is reacted at 1100℃ for 2 hours while flowing 100% CO2 gas at 5L / min. The reacted coke is then rotated 600 times in an I-type drum testing machine, and the mass yield of the coke sieved onto a 9.56mm sieve is defined as the CSR. The weight loss rate of the coke before and after the reaction at 1100℃ for 2 hours is specified as the coke reactivity index (CRI) in ISO18894.

[0005] Due to the characteristics of the measurement method, the coke strength after reaction (CSR) can be estimated from the coke strength before reaction (DI) and the coke reaction ratio (CRI). CSR has a particularly strong correlation with CRI, so in order to estimate the CSR of a coke blend, it is important to estimate the coke reaction ratio (CRI).

[0006] Patent Document 1 proposes a method for estimating the strength of blended coal coke after hot reaction by correcting the weighted average value based on the blending ratio of CSR of single coal with the coal blending effects, which are the overlap of coal softening and melting regions measured by the Giesler Plastometer method, the total average reflectance, and the maximum fluidity.

[0007] Moreover, Patent Document 2 proposes a method for estimating the reactivity of blended coal coke by weighting and averaging the reactivity of the single coal coke with the blending ratio of the single coal and correcting the result with the specific volume.

[0008] In Patent Documents 3 and 4, the CRI of a blended coal coke calculated by the weighted average of the CRI of single coal coke and the DI, which is the cold surface fracture strength, are calculated. 150 6, a method for estimating the CSR of blended coal coke has been proposed. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Unexamined Patent Publication No. 63-199286 [Patent Document 2] Japanese Patent Application Publication No. 9-263766 [Patent Document 3] JP 2005-232350 A [Patent Document 4] JP 2013-1895 A Summary of the Invention [Problem to be solved by the invention]

[0010] Most of the above-mentioned methods for estimating the CSR of blended coal coke are based on measuring the CSR and CRI of single coal coke. However, measuring CSR and CRI takes a long time. Therefore, in order to estimate the CSR of blended coal coke, it is necessary to create single coal coke for each incoming coal brand and measure its CSR and CRI, which is time-consuming. In addition, the CRI includes the influence of the residual volatile matter (VM) of the coke, which can cause variation in the measurement results.

[0011] An object of the present invention is to provide a method for quickly estimating the post-reaction strength of blended coal coke. [Means for solving the problem]

[0012] The present invention is directed to a method for quickly and simply estimating the post-reaction strength (CSR) of a blended coal coke by using thermogravimetric analysis. The present invention has the following configuration. [1] A method for estimating post-reaction strength (CSR) of a blended coal coke, comprising: When coke is held in a CO2 atmosphere at a certain temperature range for a certain time by thermogravimetry, the weight loss rate is defined as the TG reaction rate. A step of measuring the TG reaction rate of the single coal coke and estimating the TG reaction rate of the blended coal coke from a weighted average value of the TG reaction rates of the single coal coke measured; A step of estimating a reaction ratio (CRI) of the blended coal coke from the TG reaction ratio of the blended coal coke estimated in the step; and estimating a post-reaction strength (CSR) of the blended coal coke from the reaction ratio (CRI) of the blended coal coke estimated in the above step and the strength (DI) of the blended coal coke. A method for estimating the post-reaction strength of blended coal coke. [2] The method for estimating post-reaction strength of blended coal coke described in [1], wherein the thermogravimetric analysis is performed by heating the blended coal coke to a temperature range of 950°C or higher and 1100°C or lower under an inert gas atmosphere. [3] The method for estimating post-reaction strength of blended coal coke according to [1] or [2], wherein the predetermined time is 10 minutes or more and 120 minutes or less. [4] Estimating a post-reaction strength of a blended coal coke using the method for estimating post-reaction strength of a blended coal coke according to any one of [1] to [3] above, A method for producing a blended coal coke, comprising changing production conditions based on the estimated post-reaction strength of the blended coal coke. [5] Estimating a post-reaction strength of a blended coal coke using the method for estimating post-reaction strength of a blended coal coke according to any one of [1] to [3] above, A method for operating a coke oven, comprising changing operating conditions of the coke oven based on the estimated post-reaction strength of the blended coal coke. [6] Estimating a post-reaction strength of a blended coal coke using the method for estimating post-reaction strength of a blended coal coke according to any one of [1] to [3] above, A method for managing the blending ratio of simple coals, the blending ratio of simple coals being changed based on the estimated post-reaction strength of the blended coal coke. Effect of the Invention

[0013] According to the present invention, the post reaction strength (CSR) of a blended coal coke can be quickly estimated.

[0014] According to the present invention, the weight loss rate (TG reaction rate) of the single coal coke is measured by thermogravimetric analysis, the TG reaction rate of the blended coal coke is calculated from the weighted average value of the TG reaction rates, and the reaction rate (CRI) of the blended coal coke is calculated by converting it to the reaction rate (CRI) of the blended coal coke.The post-reaction strength (CSR) of the blended coal coke is estimated from the reaction rate (CRI) of the blended coal coke and the strength (DI) of the blended coal coke, thereby making it possible to quickly estimate the post-reaction strength of the blended coal coke. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a graph showing the relationship between the weighted average value of the measured TG reaction rate of single coal coke and the measured TG reaction rate of blended coal coke. [Diagram 2]FIG. 2 is a graph showing the relationship between the estimated TG reaction ratio of the blended coal coke and the actually measured reaction ratio (CRI) of the blended coal coke. [Diagram 3] FIG. 3 is a graph showing the relationship between the coke reaction strength (CSR), the coke reaction ratio (CRI), and the coke strength (DI). [Figure 4] FIG. 4 is a graph showing the relationship between the estimated CSR of a coke blend and the actually measured CSR of a coke blend. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described, however, the present invention is not limited to the following embodiment.

[0017] As mentioned above, the CSR of coke is governed by the conversion ratio of coke (CRI) and the strength of coke (DI). Therefore, in order to estimate the CSR of coke from a coal blend, it is necessary to obtain the conversion ratio of coke from the coal blend (CRI) and the strength of the coke from the coal blend (DI).

[0018] First, a method for estimating the reaction ratio (CRI) of a blended coal coke will be described. In this embodiment, the reaction ratio (CRI) of a blended coal coke is estimated by the following steps. First, a step of measuring the weight loss rate (TG reaction ratio of the blended coal coke) of the simple coal coke when held in a CO2 atmosphere at a predetermined temperature range for a predetermined time by thermogravimetric analysis is carried out. Next, a step of estimating the TG reaction ratio of the blended coal coke from the weighted average value of the TG reaction ratio of the simple coal coke measured in the above step is carried out. After that, a step of estimating the reaction ratio (CRI) of the blended coal coke from the TG reaction ratio of the blended coal coke estimated in the above step is carried out. Each step will be described below.

[0019] [Process for measuring the weight loss rate of plain coal coke (TG reaction rate of plain coal coke)] In this process, thermogravimetry (TG) is used. By using TG, it is possible to measure the change in weight over time (weight loss rate) due to the reaction of carbon in the coke with CO2 in a high-temperature 100% CO2 atmosphere. In addition, since the weight loss of the coke due to this reaction is linear, it is possible to estimate the reaction ratio (CRI) of the blended coal coke, which will be described later, even if the reaction time (measurement time) is short. In this specification, the weight loss rate when coke is held in a CO2 atmosphere at a predetermined temperature range for a predetermined time by TG is also referred to as the TG reaction rate.

[0020] In this step, the weight loss rate of the mono-charcoal coke (TG reaction rate of mono-charcoal coke) when it is held in a CO2 atmosphere at a predetermined temperature range for a predetermined time is measured by TG. The TG measurement is performed using a TG device. The mono-charcoal coke to be used as the sample for the TG measurement may be obtained by carbonizing mono-charcoal. For example, it may be mono-charcoal coke prepared by carbonizing in a can-burning test, or it may be mono-charcoal coke prepared by carbonizing a small sample obtained by reduction under certain conditions. The method of collecting the sample for TG measurement is not particularly limited. Since the amount of sample is limited due to the specifications of the TG device, it is preferable to sample so that a representative property part of the mono-charcoal coke can be obtained in order to improve the measurement accuracy. For example, it is preferable to sample according to "Coals and cokes - Sampling and sample preparation method" shown in JIS M 8811:2000.

[0021] The amount of sample to be used for TG measurement may be adjusted to the capacity and size of the TG device. In addition, the particle size of the sample to be used for TG measurement is preferably determined so that a certain number of particles can be obtained in order to obtain the representativeness of the sample. From this viewpoint, the particle size of the simple coal coke used as the sample is preferably 850 μm or less. The particle size can be adjusted by crushing the simple coal coke. In addition, the specific surface area of ​​the sample affects the reaction with CO2, and in particular, the amount of fine powder contained in the sample has a large effect on the specific surface area of ​​the sample, so it is preferable to remove fine powder with a particle size of less than 200 μm. From the above viewpoints, the particle size of the sample is preferably 200 μm or more and 850 μm or less. The particle size of the sample to be used for TG measurement can be adjusted by sieving the crushed simple coal coke with a sieve with a predetermined mesh size.

[0022] Next, the TG measurement conditions will be described. The TG measurement is performed as follows. A sample is set in the TG apparatus and heated to a predetermined temperature range under an inert gas atmosphere such as nitrogen. Then, the sample is held in a CO2 atmosphere for a predetermined time. That is, after heating to a predetermined temperature range under an inert gas atmosphere, the gas supplied to the TG apparatus is switched to CO2 gas, and the sample is held in a CO2 atmosphere for a predetermined time to perform the TG measurement. The heating rate at this time may be adjusted to the capacity of the TG apparatus. Since a faster heating rate leads to a shorter measurement time, a faster heating rate is preferable. From this viewpoint, the heating rate is preferably 20°C / min or more. In addition, the upper limit of the heating rate is not particularly limited, but the heating rate is set to a rate at which the temperature control capacity of the apparatus is insufficient during the heating process and the predetermined temperature range is not exceeded. As an example, the heating rate can be set to 150°C / min or less. It is preferable that the CO2 gas supply amount is sufficient so that the supply of CO2 gas does not limit the reaction rate during the reaction. The amount of CO2 gas supplied that does not limit the reaction rate varies depending on the amount of sample and the size of the TG device, so it is preferable to check the amount of gas required for the TG device to be used in advance. For example, for a general TG device that uses a sample of about several tens of mg as the measurement sample, the amount of CO2 gas supplied is preferably 500 mL / min or more.

[0023] The predetermined temperature range (reaction temperature with CO2) is preferably 950°C or more and 1100°C or less in order to eliminate disturbance influences such as the influence of pore structure, from the viewpoint of focusing on the reactivity of the matrix part of the coke.

[0024] The predetermined time is preferably 10 minutes or more from the viewpoint of reactivity with CO2. Also, from the viewpoint of shortening the measurement time, it is preferably 120 minutes or less. As described above, the predetermined time is a retention time in a CO2 atmosphere in a predetermined temperature range.

[0025] As described above, the weight loss rate of the simple coal coke (TG reaction rate of the simple coal coke) is measured when the simple coal coke is held in a CO2 atmosphere in a predetermined temperature range for a predetermined time.

[0026] [Process for estimating TG reaction rate of blended coal coke] Since the TG reaction rates of each single coal coke measured by TG have additivity, it is possible to estimate the TG reaction rate of a coal blended coke from the blending ratio of each single coal constituting the coal blend and the weighted average of the TG reaction rates of each single coal coke measured. In other words, it is possible to estimate the TG reaction rate of a coal blended coke when held in a CO2 atmosphere at a specified temperature range for a specified time from the measured TG reaction rate of the single coal coke.

[0027] Figure 1 shows the results of plotting the weighted average of the measured TG reaction rates of simple coal coke on the horizontal axis and the measured TG reaction rate of blended coal coke on the vertical axis. As shown in Figure 1, it can be seen that there is a correlation between the weighted average of the measured TG reaction rates of simple coal coke and the measured TG reaction rate of blended coal coke. In other words, it can be seen that the TG reaction rate of the blended coal coke after blending can be estimated based on the TG reaction rate of simple coal coke. In this process, this correlation is used to estimate the TG reaction rate of the blended coal coke from the weighted average of the measured TG reaction rates of simple coal coke.

[0028] [Process to estimate the reactivity index (CRI) of blended coal coke] In this step, the reaction ratio (CRI) of the blended coal coke is estimated from the TG reaction ratio of the blended coal coke estimated in the previous step. Figure 2 shows the relationship between the estimated TG reaction ratio of the blended coal coke and the measured reaction ratio (CRI) of the blended coal coke. As shown in Figure 2, it can be seen that there is a correlation between the estimated TG reaction ratio of the blended coal coke and the measured reaction ratio (CRI) of the blended coal coke. By utilizing this correlation and determining in advance an equation (equation (1) described below) for estimating the reaction ratio (CRI) of the blended coal coke, it is possible to estimate the reaction ratio (CRI) of the blended coal coke from the estimated TG reaction ratio of the blended coal coke.

[0029] Next, a method for estimating the post-reaction strength (CSR) of the coke blend from the estimated CRI and DI of the coke blend will be described. In this embodiment, the DI specified in JIS K 2151:2004 is used as the strength (DI) of the coke blend. 150 15 However, the strength (DI) of the blended coal coke is not limited to this, and for example, a value obtained from a known estimation formula may be used. Figure 3 shows the coke strength after reaction (CSR), the coke reaction ratio (CRI), and the coke strength (DI 150 15 ) is plotted with the horizontal axis representing the coke reaction ratio (CRI) and the vertical axis representing the coke reaction strength (CSR), and the results are shown. From FIG. 3, it can be seen that there is a strong correlation between the coke reaction strength (CSR) and the coke reaction ratio (CRI), and furthermore, the variation in the coke reaction strength (CSR) at the same coke reaction ratio (CRI) is influenced by the coke strength (DI). By utilizing this relationship, it is possible to estimate the coke reaction strength (CSR) from the coke reaction ratio (CRI) and the coke strength (DI). In this embodiment, it is possible to quickly estimate the coke reaction strength (CSR) of the blended coal coke by using the coke reaction ratio (CRI) of the blended coal coke estimated by the above-mentioned method.

[0030] In the present invention, the reactivity of each single coal coke used in blending is measured by TG, so that it is possible to predict the post-reaction strength (CSR) of the blended coal coke. Therefore, the post-reaction strength (CSR) of the blended coal coke can be quickly estimated.

[0031] By using the method for estimating the post-reaction strength of a coal blended coke of the present invention, it is possible to adjust the blending ratio of coal (simple coal) while estimating the post-reaction strength (CSR) of the coal blended coke after blending during coke production, and it is possible to produce a coal blended coke with stable CSR quality. In addition, by producing a coal blended coke while estimating the post-reaction strength (CSR) of the coal blended coke, it is possible to reduce the variation in CSR. Therefore, for example, it is possible to design the blending target to the lower limit of CSR than before, expand the range of applicable raw material quality, and reduce the production cost of the coal blended coke.

[0032] The method for producing a coke blended coal of the present invention uses the above-mentioned method for estimating the strength after reaction of a coke blended coal. Specifically, the strength after reaction of a coke blended coal is estimated using the above-mentioned method for estimating the strength after reaction of a coke blended coal, and the production conditions are changed based on the estimated strength after reaction of the coke blended coal. More specifically, the production conditions can be changed so that the estimated strength after reaction of the coke blended coal becomes a target strength. Examples of the production conditions include the blending ratio (blending rate) of coal (simple coal), etc.

[0033] The coke oven operation method of the present invention uses the above-mentioned method for estimating the post-reaction strength of a coal blended coke. Specifically, the post-reaction strength of a coal blended coke is estimated using the above-mentioned method for estimating the post-reaction strength of a coal blended coke, and the operating conditions of the coke oven are changed based on the estimated post-reaction strength of the coal blended coke. More specifically, the operating conditions of the coke oven can be changed so that the estimated post-reaction strength of the coal blended coke becomes a target strength. Examples of the operating conditions include the blending ratio of coal (simple coal).

[0034] The blending ratio control method of the present invention uses the above-mentioned method for estimating the post-reaction strength of a coal blended coke. Specifically, the post-reaction strength of a coal blended coke is estimated using the above-mentioned method for estimating the post-reaction strength of a coal blended coke, and the blending ratio of the coal blended is changed based on the estimated post-reaction strength of the coal blended coke. More specifically, the blending ratio of the coal blended coke can be changed so that the estimated post-reaction strength of the coal blended coke becomes a target strength.

[0035] According to the method for producing a blended coal coke, the method for operating a coke oven, and the method for managing the blending ratio of single coal of the present invention, by using the method for estimating post-reaction strength of a blended coal coke of the present invention described above, it is possible to enjoy the same effects as those described above. EXAMPLES

[0036] The present invention will be described below based on examples, but the present invention is not limited to the following examples.

[0037] For the blended coal coke charged in the actual furnace, the post-reaction strength (CSR) and reaction ratio (CRI) of the blended coal coke were measured according to ISO18894, and the strength (DI) of the blended coal coke was measured according to JIS K 2151:2004. 150 15 ) was measured. The carbonized material (simple coal coke) was sampled after measuring the volatile matter (VM) according to JIS M 8812:2006 for each of the simple coals used. Each of the simple coal cokes sampled was crushed and reduced to 850 μm or less, and then sieved through a 200 μm sieve to adjust the particle size from 850 μm to 200 μm or more.

[0038] For the measurement of the TG reaction rate of the single coal coke, a LINSEIS STA1600 was used as a TG device. The amount of the sample used was 0.5 g, and the temperature was raised to 950°C at 100°C / min under a N2 atmosphere. The temperature was held for 20 min until the atmosphere stabilized. After that, N2 was switched to CO2, the CO2 gas flow rate was set to 1000 mL / min, and the weight loss rate [%] = [(weight before reaction - weight after reaction) / (weight before reaction)] × 100 was measured when the sample was held (reacted) for 60 min under a CO2 atmosphere. The TG reaction rate of the blended coal coke was estimated from the weight loss rate (TG reaction rate) of the obtained single coal coke and the weighted average value of the blending rate of the single coal coke.

[0039] Next, from the correlation between the estimated TG reaction ratio of the coke blend shown in Fig. 2 and the measured reaction ratio (CRI) of the coke blend, the following equation (1) was determined to estimate the reaction ratio (CRI) of the coke blend. CRI of the coke blend (CRI) = a × (TG reaction rate of the coke blend) + b (1) Here, a and b in formula (1) are constants. In this embodiment, a = 0.55 and b = 20. The reactivity ratio (CRI) of the blended coal coke was calculated by substituting the TG reactivity ratio of the blended coal coke estimated above into formula (1).

[0040] Coke reaction strength (CSR) and coke reaction ratio (CRI) according to ISO18894, coke strength (DI, in this example DI 150 15 ) is as shown in Figure 3. From this, the regression equation for estimating the coke post-reaction strength (CSR) was determined as the following equation (2). Coke reacted strength (CSR) = c × (coke reacted ratio (CRI)) + d × (coke DI 150 15 )+e···(2) Here, c, d, and e are constants. In this embodiment, c=-1.4, d=0.91, and e=24. The reaction ratio (CRI) of the blended coal coke calculated by the formula (1) and the strength (DI) of the blended coal coke actually measured are compared with the formula (2).150 15 ) and the actually measured CSR of blended coal coke is shown in Fig. 4. As shown in Fig. 4, the method for estimating the CSR of blended coal coke of the present invention makes it possible to estimate the CSR of blended coal coke based on the TG reaction rate of simple coal coke measured by TG.

Claims

1. A method for estimating a post-reaction strength (CSR) of a blended coal coke, comprising: Thermogravimetric analysis revealed that CO ２ When the weight loss rate when the coke is held in a given temperature range under an atmosphere for a given time is defined as the TG reaction rate, measuring the TG reaction rate of the single coal coke and estimating the TG reaction rate of the blended coal coke from a weighted average value of the TG reaction rates of the single coal coke measured; A step of estimating a reaction ratio (CRI) of the blended coal coke from the TG reaction ratio of the blended coal coke estimated in the above step based on a correlation between the TG reaction ratio and the reaction ratio (CRI) of the blended coal coke that has been previously obtained; and a step of estimating a post-reaction strength (CSR) of the blended coal coke from the reaction ratio (CRI) of the blended coal coke estimated in the step and the strength (DI) of the blended coal coke based on a correlation between the reaction ratio (CRI) of the blended coal coke corresponding to the strength (DI) of the blended coal coke and the post-reaction strength (CSR) of the blended coal coke, which is determined in advance. A method for estimating the post-reaction strength of blended coal coke.

2. The method for estimating post-reaction strength of blended coal coke according to claim 1 , wherein the thermogravimetric analysis involves heating to a temperature range of 950° C. or more and 1100° C. or less under an inert gas atmosphere.

3. The method for estimating post-reaction strength of blended coal coke according to claim 1 , wherein the predetermined time is from 10 minutes to 120 minutes.

4. The method for estimating post-reaction strength of blended coal coke according to claim 2 , wherein the predetermined time is from 10 minutes to 120 minutes.

5. The method for estimating post-reaction strength of a coal blended coke according to any one of claims 1 to 4 is used to estimate the post-reaction strength of the coal blended coke, A method for producing a blended coal coke, comprising changing production conditions based on the estimated post-reaction strength of the blended coal coke.

6. The method for estimating post-reaction strength of a coal blended coke according to any one of claims 1 to 4 is used to estimate the post-reaction strength of the coal blended coke, A method for operating a coke oven, comprising changing operating conditions of the coke oven based on the estimated post-reaction strength of the blended coal coke.

7. The method for estimating post-reaction strength of a coal blended coke according to any one of claims 1 to 4 is used to estimate the post-reaction strength of the coal blended coke, A method for managing the blending ratio of simple coals, the blending ratio of simple coals being changed based on the estimated post-reaction strength of the blended coal coke.

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