Method for detecting coke reactivity of coking coal after coking

Abstract

The invention provides a method for detecting the reactivity of coke after coking coal is coked, and belongs to the technical field of reactivity evaluation of metallurgical cokes, and the method comprises the following steps of: performing high-temperature destructive distillation on the coking coal in an inert atmosphere to form coke by utilizing a temperature system of a thermogravimetric analyzer, and reacting the coke in a carbon dioxide atmosphere. The temperature schedule of the whole process firstly simulates high-temperature dry distillation of the coking coal in the coke oven, and then simulates the use temperature of the coke in the blast furnace to carry out gasification reaction. And the coking reactivity of the coking coal can be conveniently detected by utilizing the characteristic that the thermogravimetric analyzer automatically controls the temperature and the atmosphere. The convenience degree of predicting the coke reactivity of the coking coal after coking by using the thermogravimetric analyzer is obviously higher than that of a chemical analysis method in the prior art, and the price of the thermogravimetric analyzer is obviously lower than that of an X-ray fluorescence spectrophotometer. The coke reactivity can be conveniently and accurately predicted through the thermogravimetric analyzer, ash component analysis and ash distribution are prevented from being considered, the test cost is low, and the efficiency is high.

Description

Technical Field

[0001] The invention relates to the technical field of reactivity evaluation of metallurgical coke, and in particular to a method for detecting the reactivity of coke after coking coal is coked. Background Art

[0002] Coke is a solid product after high-temperature dry distillation of coking coal and is an important raw material for blast furnace ironmaking. Coke reactivity is usually evaluated by the reaction characteristics of coke with carbon dioxide. Most countries use the coke reactivity index (CRI) to express this characteristic. my country's national standard test method is GB / T4000-2017. The test method is to place a certain amount of coke sample in a high-temperature reactor, react with carbon dioxide at a temperature of 1100°C for 2 hours, and express the CRI of coke as the percentage of coke mass loss. Coke requires a suitable CRI. Excessive reactivity will aggravate the carbon loss of coke, reduce the post-reaction strength of coke, and affect the smooth progress of blast furnace ironmaking.

[0003] At present, the catalytic index of coking coal is usually used to predict the reactivity of coking coal after coking. The catalytic index of coking coal refers to the quantitative index of the catalytic effect of the ash components in coal on the reactivity of CO2. Different ash components have different catalytic effects on the reactivity of CO2. By assigning different weights to different ash components, the influence of ash components on the reactivity of coke can be reflected. For example, components such as Na2O, K2O, CaO, MgO, and Fe2O3 have a positive catalytic effect on the reaction rate of coke and CO2, while components such as SiO2, Al2O3 and TiO2 have an inhibitory effect. There are two methods for analyzing coal ash components: chemical analysis and instrumental analysis. The chemical analysis method requires simple equipment and accurate results, but has many operation steps and a long time. The instrumental analysis method uses expensive precision instruments to obtain results more quickly, such as X-ray fluorescence spectrometers. The effect of catalytic elements on the reactivity of coke depends not only on the content of catalytic elements, but also on the distribution of catalytic elements. Whether it is a chemical analysis method or an instrumental analysis method, it can only test the content of catalytic elements in coking coal but cannot characterize the distribution of ash. Therefore, there is a deviation in the reactivity of coking coal after it is made into coke using ash composition.

[0004] Yan Hui et al. invented a method for detecting the catalytic effect of coal ash components, using the average maximum reflectivity of the vitrinite group of coal as a reflection of the influence of the coal-forming environment and ash dispersion (CN117969459A). Wang Lixin et al. invented a method and system for predicting the reactivity results of coke for metallurgical blast furnaces, using regression analysis to study the relationship between coke reactivity and its physical and chemical indicators, and solving the problems of hysteresis, low efficiency and low utilization rate of the existing GB / T4000-2017 method (CN117935954A). Qiu Shuxing et al. invented a method for characterizing the reactivity of coke based on the volume of carbon microcrystals, and used X-ray spectra to infer the reactivity of coke (CN117405714A). Wang Yue et al. invented a method for predicting the quality of coke using the reflectivity of coking coal vitrinite, the content of inert components and the bonding index, and the prediction indicators include coke reactivity (CN118351978A). Zhao Yan and others invented a method for evaluating the reactivity of coal and biomass coke using a thermogravimetric analyzer to solve the problem of insufficient evaluation indicators for the combustion and gasification reactivity of coal coke and biomass coke. However, the above methods either use expensive instruments, have high detection costs, or require ash composition analysis and characterization of ash distribution, resulting in low detection efficiency. Therefore, the prior art urgently needs a convenient method to predict the reactivity of metallurgical coke formed by high-temperature carbonization of coking coal. Summary of the invention

[0005] The object of the present invention is to provide a method for detecting the reactivity of coke after coking coal is coked. The detection method provided by the present invention can conveniently and accurately predict the reactivity of coke, avoid considering ash composition analysis and ash distribution, and has low testing cost and high efficiency.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for detecting the coke reactivity of coking coal after coking, comprising the following steps: after a coking coal sample to be tested is loaded into a crucible, the crucible is placed in a thermogravimetric analyzer, and then the crucible is heated to 1100° C. under the condition of passing an inert gas, and then the crucible is switched to the condition of passing carbon dioxide, and the crucible is kept at 1100° C. for reaction for 18 to 22 minutes; the coking reactivity of the coking coal is calculated by using the data detected by the thermogravimetric analyzer and the following formula 1, so as to predict the coke reactivity index CRI of the coking coal sample to be tested after coking;

[0008] CCR = (m0-m1) × 100 / m0 (Equation 1);

[0009] Wherein, CCR is the coking reactivity of coking coal, m0 is the residual mass of the coking coal sample to be tested when it reaches 1100°C, and m1 is the residual mass of the coking coal sample to be tested after the heat preservation reaction at 1100°C.

[0010] Preferably, the mass of the coking coal sample to be tested is 180-220 mg.

[0011] Preferably, the crucible is made of at least one of alumina, platinum and zirconium oxide.

[0012] Preferably, the inert gas is nitrogen or argon.

[0013] Preferably, the inert gas introduction rate is 80-120 mL / min.

[0014] Preferably, the inert gas introduction rate is 90-110 mL / min.

[0015] Preferably, the heating rate is 1-5°C / min.

[0016] Preferably, the heating rate is 2-4°C / min.

[0017] Preferably, the carbon dioxide introduction rate is 80-120 mL / min.

[0018] Preferably, the carbon dioxide introduction rate is 90-110 mL / min.

[0019] The present invention provides a method for detecting the reactivity of coke after coking of coking coal. The temperature system of a thermogravimetric analyzer is used to firstly cause the coking coal to undergo high-temperature dry distillation in an inert atmosphere to form coke, and then cause the coke to react in a carbon dioxide atmosphere. The temperature system of the entire process firstly imitates the high-temperature dry distillation of coking coal in a coke oven, and then imitates the gasification reaction of coke under the conditions of the use temperature of the coke in a blast furnace. The coking reactivity of coking coal can be conveniently detected by utilizing the convenient automatic control of temperature and atmosphere by the thermogravimetric analyzer. Moreover, the convenience of the present invention in predicting the reactivity of coke after coking of coking coal by using a thermogravimetric analyzer is significantly higher than that of the chemical analysis method in the prior art, and the price of the thermogravimetric analyzer is significantly lower than that of an X-ray fluorescence spectrometer. The present invention can conveniently and accurately predict the reactivity of coke through a thermogravimetric analyzer, avoids considering the analysis of ash composition and the distribution of ash, and has low testing cost and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The pyrolysis and gasification process curves of coking coals 1 to 5 respectively detected by thermogravimetric analysis in Examples 1 to 5 of the present invention;

[0021] Figure 2 The present invention uses the CCR detected in Examples 1 to 5 as the ordinate and the CRI detected in Comparative Examples 1 to 5 as the abscissa to draw a linear regression line graph, wherein the linear regression equation is CCR=1.6×CRI+1.6185, R 2 =0.9724. DETAILED DESCRIPTION

[0022] The present invention provides a method for detecting the coke reactivity of coking coal after coking, comprising the following steps: after a coking coal sample to be tested is loaded into a crucible, the crucible is placed in a thermogravimetric analyzer, and then the crucible is heated to 1100° C. under the condition of passing an inert gas, and then the crucible is switched to the condition of passing carbon dioxide, and the crucible is kept at 1100° C. for reaction for 18 to 22 minutes; the coking reactivity of the coking coal is calculated by using the data detected by the thermogravimetric analyzer and the following formula 1, so as to predict the coke reactivity index CRI of the coking coal sample to be tested after coking;

[0023] CCR = (m0-m1) × 100 / m0 Formula 1;

[0024] Wherein, CCR is the coking reactivity of coking coal, m0 is the residual mass of the coking coal sample to be tested when it reaches 1100°C, and m1 is the residual mass of the coking coal sample to be tested after the heat preservation reaction at 1100°C.

[0025] In the present invention, unless otherwise specified, the raw materials used are conventional commercial products in the art.

[0026] In the present invention, the mass of the coking coal sample to be tested is preferably 180-220 mg, more preferably 190-210 mg, and further preferably 200 mg. The present invention controls the mass of the coking coal sample to be tested within the above range to ensure its full reaction, improve the accuracy and precision of the data detected by the thermogravimetric analyzer, and improve the repeatability and accuracy of the detection method.

[0027] In the present invention, the material of the crucible is preferably at least one of alumina, platinum and zirconia.

[0028] In the present invention, the inert gas is preferably nitrogen or argon. In the present invention, the inert gas introduction rate is preferably 80-120 mL / min, more preferably 90-110 mL / min, and further preferably 100 mL / min. The present invention controls the introduction rate of the inert gas within the above range to protect the coal sample from oxidation and take away the pyrolysis gas, to avoid too low an inert gas flow rate failing to smoothly take away the volatile gas of the coal, and to avoid too high an inert gas flow rate affecting heat transfer, causing the system temperature rise accuracy to decrease, and also wasting reaction gas.

[0029] In the present invention, the heating rate of the heating temperature is preferably 1-5°C / min, more preferably 2-4°C / min, and further preferably 3°C / min. The present invention controls the heating rate of the heating temperature within the above range to promote high-temperature dry distillation of coking coal in an inert atmosphere to form coke, fully generate volatile matter, and improve the repeatability and accuracy of the detection method.

[0030] The present invention heats the temperature to 1100° C. and keeps the temperature at 1100° C. for reaction, so as to obtain more accurate detection data using the thermogravimetric analyzer within a shorter reaction time, thereby improving efficiency, avoiding affecting the resolution of experimental detection, and improving the repeatability and accuracy of the detection method.

[0031] In the present invention, the carbon dioxide introduction rate is preferably 80-120 mL / min, more preferably 90-110 mL / min, and further preferably 100 mL / min. The present invention controls the carbon dioxide introduction rate within the above range to ensure that the coal sample reacts fully with the carbon dioxide, to avoid too low a carbon dioxide flow rate from being unable to supply highly reactive coal for reaction; and to avoid too high a carbon dioxide flow rate from affecting heat transfer, causing a decrease in the system insulation effect, and wasting reaction gas.

[0032] In the present invention, the time of the heat preservation reaction is preferably 20 minutes. The present invention controls the temperature and time of heating and stirring within the above range to ensure the reaction degree of the coking coal, improve the degree of differentiation of coals with different reactivities, and improve the repeatability and accuracy of the detection method.

[0033] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. 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.

[0034] In the present invention, coking coal 1 comes from the Donghuantuo mine in Kailuan, coking coal 2 comes from the Lvjiatuo mine in Kailuan, coking coal 3 comes from the Tangshan mine in Kailuan, coking coal 4 comes from the Linxi mine in Kailuan, and coking coal 5 comes from imported coal from Russia.

[0035] Example 1

[0036] A method for detecting the reactivity of coke after coking coal is coked, the steps are as follows:

[0037] 200 mg of coking coal 1 was loaded into an alumina crucible and placed in a thermogravimetric analyzer and heated from room temperature to 1100°C at a heating rate of 3°C / min. 100 mL / min of nitrogen was introduced during the heating process. After reaching 1100°C, the nitrogen was changed to 100 mL / min of carbon dioxide. The temperature was kept at 1100°C for 20 minutes. The coking reactivity of the coking coal was calculated using the data detected by the thermogravimetric analyzer and the following formula 1, which was used to predict the coke reactivity index CRI of the coking coal sample to be tested after coking. The results are shown in Table 1.

[0038] CCR = (m0-m1) × 100 / m0 (Equation 1);

[0039] Wherein, CCR is the coking reactivity of coking coal, m0 is the residual mass of the coking coal sample to be tested when it reaches 1100°C, and m1 is the residual mass of the coking coal sample to be tested after the heat preservation reaction at 1100°C.

[0040] Embodiments 2 to 5

[0041] The coke reactivity of the coking coal after coking was detected according to the method of Example 1. The difference from Example 1 is that Examples 2 to 5 respectively use coking coal 2, coking coal 3, coking coal 4 and coking coal 5 as the coking coal samples to be tested.

[0042] Comparative Examples 1 to 5

[0043] Coking coal 1, coking coal 2, coking coal 3, coking coal 4 and coking coal 5 were respectively made into coke using a 40kg semi-industrial test coke oven. The CRI index of the corresponding coke was tested according to the national standard GB / T 4000-2017. The results are shown in Table 1.

[0044] Table 1 CCR index detected in Examples 1 to 5 and CRI index detected in Comparative Examples 1 to 5

[0045] sample CRI, % CRR,% Coking coal1 39.83 68.7 Coking coal 2 23.85 37.2 Coking coal 3 28.85 50.3 Coking coal 4 24.07 39.6 Coking coal 5 47.72 75.2

[0046] In Examples 1 to 5, the pyrolysis and gasification process curves of coking coals 1 to 5 were respectively detected by thermogravimetric analysis as shown in FIG. Figure 1 shown.

[0047] In order to verify whether CCR can reflect the reactivity of coking coal after coking, the CCR detected in Examples 1 to 5 was used as the ordinate, and the CRI detected in Comparative Examples 1 to 5 was used as the abscissa, and the linear regression equation was obtained as CCR=1.6×CRI+1.6185, where R 2 =0.9724, and the linear regression line is plotted as Figure 2 As shown in Table 1 and Figure 2 It can be seen that the CCR index tested in the embodiment of the present invention has a good correlation with the CRI index of the coke tested in the comparative example, and the CCR index can more fully reflect the reactivity of the coking coal after coking.

[0048] The ash composition of coking coals 1 to 5 was tested by X-ray fluorescence spectrometry. The results are shown in Table 2.

[0049] Table 2 Ash composition test results of coking coals 1 to 5 (wt%)

[0050] Components Coking coal1 Coking coal 2 Coking coal 3 Coking coal 4 Coking coal 5 Silicon dioxide 44.30 45.80 43.02 40.60 47.60 Aluminum oxide 31.78 40.44 37.80 36.94 26.60 Iron (III) oxide 9.81 3.00 4.96 2.96 8.10 Titanium Dioxide 1.74 1.85 1.88 2.00 1.00 Calcium Oxide 3.87 3.15 3.57 6.52 5.20 Magnesium oxide 1.54 0.87 1.02 1.38 1.50 Sulfur trioxide 2.75 2.05 2.90 3.75 5.00 Phosphorus pentoxide 1.23 0.90 1.20 1.06 0.02 Potassium Oxide 0.55 0.33 0.35 0.15 3.90 Sodium oxide 0.25 0.24 0.31 0.52 0.45 Manganese dioxide 0.04 0.00 0.01 0.00 0.09

[0051] The sum of the components in Table 2 is less than 100 wt %, and the remaining unspecified components are oxides of other trace elements.

[0052] As can be seen from Table 2, coking coal 1 has a higher iron oxide content, and coking coal 5 has higher iron oxide and potassium oxide contents. Both components will catalyze the reaction between coke and carbon dioxide. The CCR and CRI indicators of these two coals are relatively high. Coking coal 4 has a higher calcium oxide content, but the CCR and CRI indicators of coking coal 4 are not high. Calcium oxide will also catalyze the reaction between coke and carbon dioxide. Since the distribution of catalytic minerals is not considered, the judgment of the reactivity of coking coal 4 is biased. This shows that the method provided by the present invention is more accurate in predicting the reactivity of coke using the CCR indicator than using ash components.

[0053] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for detecting the reactivity of coke after coking coal is coked, characterized in that: The following steps are involved: The coking coal sample to be tested is placed in a crucible and placed in a thermogravimetric analyzer, and then heated to 1100° C. under the condition of passing inert gas, and then switched to the condition of passing carbon dioxide and kept at 1100° C. for reaction for 18 to 22 minutes; the reactivity of the coking coal after coking is calculated using the data detected by the thermogravimetric analyzer and the following formula 1, which is used to predict the coke reactivity index CRI of the coking coal sample to be tested after coking; CCR = (m0-m1) × 100 / m0 (Equation 1); Wherein, CCR is the coking reactivity of coking coal, m0 is the residual mass of the coking coal sample to be tested when it reaches 1100°C, and m1 is the residual mass of the coking coal sample to be tested after the heat preservation reaction at 1100°C.

2. The detection method according to claim 1, characterized in that: The mass of the coking coal sample to be tested is 180-220 mg.

3. The detection method according to claim 1, characterized in that: The material of the crucible is at least one of alumina, platinum and zirconium oxide.

4. The detection method according to claim 1, characterized in that: The inert gas is nitrogen or argon.

5. The detection method according to claim 1 or 4, characterized in that: The inert gas introduction rate is 80-120 mL / min.

6. The detection method according to claim 5, characterized in that: The inert gas introduction rate is 90-110 mL / min.

7. The detection method according to claim 1, characterized in that: The heating rate of the heating is 1-5°C / min.

8. The detection method according to claim 1, characterized in that: The heating rate of the heating is 2-4°C / min.

9. The detection method according to claim 1, characterized in that: The carbon dioxide introduction rate is 80-120 mL / min.

10. The detection method according to claim 9, characterized in that: The carbon dioxide introduction rate is 90-110 mL / min.

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