Coking coal mixing identification method

Abstract

The invention provides a method for identifying mixed coal of coking coals, which comprises the following steps of: performing thermogravimetric analysis test on the coking coals with different metamorphic degrees to obtain test data; establishing a reference curve according to the test data; carrying out thermogravimetric analysis test on the coking coal to be detected to obtain data to be detected; constructing a differential thermal analysis curve according to the to-be-detected data; and obtaining an identification result through a comparison result of the differential thermal analysis curve and the reference curve. According to the method, data comparison is carried out through thermogravimetric analysis testing, the accuracy of coking coal identification is improved, the traditional identification process is simplified, and the cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of identification and evaluation of coking coal and mixed coal, and in particular to a method for identifying coking coal and mixed coal. Background Art

[0002] Coke is an irreplaceable raw material for blast furnace ironmaking. Coking coal is the raw material for making coke, and the properties of coking coal are important factors affecting the performance of coke. At present, the properties of coking coal are usually evaluated by indicators such as volatile matter content, bonding index, colloidal layer index, Oa expansion, Gibbs fluidity, and vitrinite reflectivity. At present, the identification of mixed coal is mainly achieved by analyzing the vitrinite reflectivity histogram, and the coefficient of variation of the random reflectivity distribution of the vitrinite of the coal is used to determine whether it is a single coal or a blended coal.

[0003] However, the identification of mixed coal by analyzing the vitrinite reflectance histogram requires the use of a dedicated coal petrographic microscope, which is expensive, and the sample used for testing requires a special pulverized coal molding, grinding and polishing process, which is relatively cumbersome. Therefore, it is very necessary to design a method for identifying coking coal mixed coal. Summary of the invention

[0004] The purpose of the present invention is to provide a method for identifying coking coal and mixed coal, to improve the accuracy of coking coal identification by performing data comparison through thermogravimetric analysis test, and to simplify the traditional identification process to reduce costs.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A method for identifying coking coal mixed coal comprises the following steps:

[0007] Conduct thermogravimetric analysis tests on coking coal with different degrees of metamorphism to obtain test data;

[0008] Establish reference curve based on test data;

[0009] Perform thermogravimetric analysis on the coking coal to be tested to obtain the data to be tested;

[0010] Constructing a differential thermal analysis curve according to the data to be detected;

[0011] The identification result is obtained by comparing the differential thermal analysis curve with the reference curve.

[0012] Optionally, coking coal with different degrees of metamorphism includes: first coking coal, second coking coal and third coking coal; the maximum reflectivity ranges of the first coking coal, the second coking coal and the first coking coal are 0.6-0.8, 0.9-1.1 and 1.3-1.5 respectively, and the standard deviation ranges of the first coking coal, the second coking coal and the first coking coal are 0.06-0.09, 0.06-0.1 and 0.1-0.14 respectively.

[0013] Optionally, the expression of the reference curve is: R=aT+b; wherein R is the weight loss rate, T is the temperature, and a and b are both constants.

[0014] Optionally, the identification result is obtained by comparing the differential thermal analysis curve with the reference curve, including:

[0015] The actual fastest pyrolysis rate and the actual fastest temperature are obtained according to the differential thermal analysis curve;

[0016] According to the actual fastest temperature, a reference pyrolysis rate on the reference curve is obtained;

[0017] A judgment formula is constructed based on the actual fastest pyrolysis rate and the reference pyrolysis rate;

[0018] A comparison result is obtained according to the judgment formula, and a recognition result is obtained according to the comparison result.

[0019] Optionally, the judgment formula is expressed as: M = R d / R c ; Among them, M is the comparison result, R d is the actual fastest pyrolysis rate, R c is the reference pyrolysis rate.

[0020] Optionally, a comparison result is obtained according to a judgment formula, and an identification result is obtained according to the comparison result, specifically: if the comparison result is greater than or equal to 1, the identification result is determined to be single coal; if the comparison result is less than 1, the identification result is determined to be mixed coal.

[0021] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: the method for identifying coking coal mixed coal provided by the present invention comprises: performing thermogravimetric analysis test on coking coal with different metamorphic degrees to obtain test data; establishing a reference curve according to the test data; performing thermogravimetric analysis test on the coking coal to be tested to obtain data to be tested; constructing a differential thermal analysis curve according to the data to be tested; and obtaining an identification result by comparing the differential thermal analysis curve with the reference curve. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 The present invention is a flow chart of the method for identifying coking coal mixed coal;

[0024] Figure 2 It is the DTG curve principle diagram of the present invention;

[0025] Figure 3 This is a thermogravimetric (DTG) curve of a standard sample according to an embodiment of the present invention;

[0026] Figure 4 is a reference curve diagram of an embodiment of the present invention;

[0027] Figure 5 This is a DTG curve diagram of the coking coal to be tested according to an embodiment of the present invention;

[0028] Figure 6 This is a relationship diagram between the DTG peak value of the coking coal to be detected and the reference curve in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] like Figure 1 As shown, the present invention provides a method for identifying coking coal mixed coal, comprising the following steps:

[0032] Step 100: Perform thermogravimetric analysis on coking coal with different degrees of metamorphism to obtain test data.

[0033] Specifically, three types of single coking coal with different metamorphic degrees were selected for thermogravimetric analysis. The first type was coking coal with a lower metamorphic degree, whose vitrinite average maximum reflectance R max The second type is coking coal with medium metamorphism, whose R max The third type is coking coal with a higher degree of metamorphism, whose R max The value of the three coals was between 1.3 and 1.5, and the standard deviation was between 0.10 and 0.14. Then the three coals were used as samples for thermogravimetric analysis.

[0034] The specific process of the thermogravimetric analysis test is as follows: 200 mg of sample is loaded into an alumina crucible and placed in a thermogravimetric analyzer, and then the alumina crucible is heated from room temperature to 600°C at a heating rate of 3°C / min, and 100 ml / min of nitrogen or argon is introduced during the heating process.

[0035] Step 200: Establish a reference curve based on test data.

[0036] Specifically, a thermogravimetric analyzer is used to record the data of the thermogravimetric analysis test process, and a differential thermal analysis (DTG) curve of a typical single type of coal with different degrees of metamorphism is constructed. The temperature T (°C) and the corresponding weight loss rate R (% / min) at which the three types of coking coal lose weight fastest during pyrolysis are found on the thermogravimetric DTG curve, which are recorded as T1, T2, T3 and R1, R2, R3, respectively. A linear function relationship between R and T is established by linear regression to obtain a reference curve. The expression of the reference curve is:

[0037] R = aT + b;

[0038] Where R is the weight loss rate, T is the temperature, and a and b are constants.

[0039] Step 300: Perform a thermogravimetric analysis test on the coking coal to be tested to obtain test data.

[0040] Step 400: construct a differential thermal analysis (DTG) curve according to the data to be detected.

[0041] Step 500: Obtaining an identification result by comparing a differential thermal analysis (DTG) curve with a reference curve.

[0042] Specifically, the actual fastest pyrolysis rate and the corresponding actual fastest temperature with the fastest pyrolysis rate are found on the DTG curve formed by the data to be detected. Then, the reference pyrolysis rate corresponding to the actual fastest temperature is found on the reference curve. Then, a judgment formula is constructed based on the actual fastest pyrolysis rate and the reference pyrolysis rate. Finally, the coking coal is identified based on the comparison results calculated by the judgment formula to obtain an identification result.

[0043] Specifically, the expression of the judgment formula is:

[0044] M=R d / R c ;

[0045] Among them, M is the comparison result, R d is the actual fastest pyrolysis rate, R c is the reference pyrolysis rate.

[0046] It should be noted that the molecular structure of coal with a low degree of metamorphism has long side chains and more functional groups, and the pyrolysis rate is higher at a lower temperature; the molecular structure of coal with a high degree of metamorphism has short side chains and fewer functional groups, and the pyrolysis rate is lower at a higher temperature. Figure 2 As shown in the figure, after coals with different metamorphic degrees are mixed together, the additivity of the pyrolysis curves is better. The pyrolysis DTG curve of the mixed coal can be approximately calculated by adding the curves of the single coals point by point. Since the pyrolysis of coal with a low degree of metamorphism occurs at a lower temperature and a faster rate, the highest point of the DTG curve of the mixed coal will be biased towards the coal with a low degree of metamorphism, and the highest point of its DTG peak will be significantly reduced.

[0047] Furthermore, if the peak value of the DTG curve of the pyrolysis of the coking coal to be tested is significantly lower than the peak value of the reference curve, it means that the coking coal to be tested is a mixture of two coals with different degrees of metamorphism. M represents the degree to which the peak value of the DTG curve of the pyrolysis of the coking coal to be tested deviates from the reference line. If M is greater than or equal to 1, it means that the DTG peak value of the coal to be tested is exactly on the reference curve or above the reference curve, and the coking coal to be tested is single coal; if M is less than 1, it means that the DTG peak value of the coal to be tested is below the reference curve, and the coking coal to be tested is mixed coal. The smaller the M value, the more serious the mixed coal.

[0048] The present invention provides an embodiment, using three single coking coals with different metamorphic degrees as calibration samples, and the coal of calibration sample 1 is selected from the average maximum reflectance R max The standard deviation of the coking coal is 0.76, which is produced from the No. 1 mine of a certain group, and the standard deviation is 0.092. max The standard deviation of the coking coal is 1.07, which is produced from the No. 2 mine of a certain group, and is 0.062. max The standard deviation of the coking coal is 1.45, which is produced from the No. 3 mine of a certain group. The standard deviation is 0.123. The three calibration samples were respectively loaded into alumina crucibles and placed in a thermogravimetric analyzer. The alumina crucible was then heated from room temperature to 600°C at a heating rate of 3°C / min, and 100ml / min of nitrogen or argon was introduced during the heating process. The data recorded by the thermogravimetric analyzer were obtained as follows Figure 3 Thermogravimetric (DTG) curves of three types of coking coal are shown.

[0049] As shown in Table 1, the fastest temperatures T (°C) and corresponding weight loss rates R (% / min) of the three coking coals were found on the thermogravimetric (DTG) curves, which are T1, T2, T3 and R1, R2, R3 respectively.

[0050] Table 1 DTG curve data table

[0051] T(℃) R(% / min) Standard sample 1 423 0.67 Standard 2 443 0.57 Standard 3 465 0.41

[0052] Thus, the linear relationship between R and T is established by regression, and the following is obtained: Figure 4 The reference curve shown is expressed as: R = -0.0062T + 3.3045.

[0053] Then, two kinds of coking coal to be tested were used as test samples and tested separately. They were also loaded into alumina crucibles and placed in a thermogravimetric analyzer. The alumina crucible was then heated from room temperature to 600°C at a heating rate of 3°C / min, and 100ml / min of nitrogen or argon was introduced during the heating process. The data recorded by the thermogravimetric analyzer were obtained as follows: Figure 5 The DTG curve of the coking coal to be tested is shown in FIG. Figure 6 The relationship between the DTG peak value and the reference curve is shown, and the fastest pyrolysis rate value R of the DTG curve of the coking coal to be tested is found d and the corresponding temperature T d . Find the temperature T on the reference curve d The corresponding rate R c , the degree of mixed coal M is calculated by the judgment formula, and the calculation parameters are shown in Table 2:

[0054] Table 2 Calculation parameters of coking coal to be tested

[0055]

[0056]

[0057] According to the size of the coal mixing degree M, it is judged that the two test samples of coal are mixed coal, which is the same as the identification results of the two test samples of coal according to the method of GB / T397-2022, verifying the correctness of the method of the present invention.

[0058] The beneficial effects of the present invention are as follows:

[0059] 1) Thermogravimetric analysis is used to identify coking coal. General scientific instruments can be used in the testing process, and a dedicated coal rock microscope is not required. The preparation of the test sample is simple, and conventional crushing and reduction are sufficient, which simplifies the cumbersome pulverized coal molding, grinding and polishing process and reduces costs.

[0060] 2) The accuracy of coking coal identification is improved by taking the ratio of the fastest actual pyrolysis rate value to the reference pyrolysis rate of its temperature on the reference curve as the judgment basis.

[0061] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0062] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for identifying coking coal mixed coal, characterized in that: The steps include: Conduct thermogravimetric analysis tests on coking coal with different degrees of metamorphism to obtain test data; Establishing a reference curve according to the test data; Perform the thermogravimetric analysis test on the coking coal to be tested to obtain the data to be tested; Constructing a differential thermal analysis curve according to the data to be detected; The identification result is obtained by comparing the differential thermal analysis curve with the reference curve.

2. The method for identifying coking coal and mixed coal according to claim 1, characterized in that: The coking coals of different metamorphic degrees include: first coking coal, second coking coal and third coking coal; the maximum reflectivity ranges of the first coking coal, the second coking coal and the first coking coal are: 0.6-0.8, 0.9-1.1 and 1.3-1.5 respectively, and the standard deviation ranges of the first coking coal, the second coking coal and the first coking coal are: 0.06-0.09, 0.06-0.1 and 0.1-0.14 respectively.

3. The method for identifying coking coal and mixed coal according to claim 1, characterized in that: The expression of the reference curve is: R=aT+b; wherein R is the weight loss rate, T is the temperature, and a and b are both constants.

4. The method for identifying coking coal and mixed coal according to claim 1, characterized in that: Obtaining an identification result by comparing the differential thermal analysis curve with the reference curve includes: According to the differential thermal analysis curve, the actual fastest pyrolysis rate and the actual fastest temperature are obtained; Obtaining a reference pyrolysis rate on the reference curve according to the actual fastest temperature; Constructing a judgment formula according to the actual fastest pyrolysis rate and the reference pyrolysis rate; The comparison result is obtained according to the judgment formula, and the recognition result is obtained according to the comparison result.

5. The method for identifying coking coal and mixed coal according to claim 4, characterized in that: The expression of the judgment formula is: M = R d / R c ; Wherein, M is the comparison result, R d is the actual fastest pyrolysis rate, R c is the reference pyrolysis rate.

6. The method for identifying coking coal and mixed coal according to claim 4, characterized in that: The comparison result is obtained according to the judgment formula, and the identification result is obtained according to the comparison result, specifically: if the comparison result is greater than or equal to 1, the identification result is determined as a single coal; If the comparison result is less than 1, the identification result is determined to be mixed coal.

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