Method for quantitatively predicting coke lumpiness by matching lean coal in coking coal

Abstract

The invention relates to the technical field of metallurgical raw materials and coking coal blending, in particular to a method for quantitatively predicting coke lumpiness by blending lean coal in coking coal, the coke lumpiness is predicted by using a pyrolysis shrinkage coefficient of blended coal after lean coal blending, and the blended coal comprises gas coal, 1 / 3 coking coal, fat coal, coking coal and lean coal. Comprising the following steps: respectively crushing different types of coal samples to be less than 0.2 mm, and mixing to prepare a coal sample of mixed coal; the method comprises the following steps: preparing a coal pen of blended coal according to a bituminous coal Arnu dilatometer test method, measuring a coal sample pyrolysis shrinkage curve of the blended coal by using a coking coal pyrolysis shrinkage tester, and calculating a shrinkage coefficient X; according to the obtained shrinkage coefficient, calculating the average lumpiness of the coke smelted by the mixed coal through a coke lumpiness prediction formula; in the coking process, the lumpiness of the smelted coke is predicted in advance according to the thermal expansion contractibility of the blended coal, and whether the smelted coke meets the requirements of metallurgical coke or not is helped to be judged, so that the trial and error cost and the time cost are effectively reduced, and the coke production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical raw materials and coking coal blending, and in particular to a method for quantitatively predicting coke particle size by blending lean coal into coking coal. Background Art

[0002] With the development and utilization of technologies such as the large-scale blast furnace, the increase in coal injection ratio and hydrogen-rich raw materials, higher requirements are placed on the performance of coke. Especially in the context of extended residence time in the blast furnace and a significant reduction in coke ratio, the size of coke has become an important consideration.

[0003] Larger coke agglomerates improve blast furnace air permeability and coke skeletal function, reducing coke breakage and pulverization, thereby increasing blast furnace utilization and reducing coke ratio. Therefore, controlling and optimizing coke agglomeration has become a critical issue urgently needed in the steel industry. Existing literature has extensively studied the effects of the thermal expansion and contraction properties of individual coking coals on the agglomeration properties of coking coals produced from these coals. Using a modified Oya dilatometer, the shrinkage characteristics of coking coals of varying metamorphicity during pyrolysis were investigated. The results showed that the thermal contraction coefficient significantly influences the agglomeration properties of coke. However, these studies primarily focused on a single coking coal type, and there has been no systematic and in-depth study of the blending of multiple coals widely used in actual production. In actual coking, to reduce costs and improve coke quality, it is often necessary to blend coking coals of varying properties. Due to the varying expansion and contraction properties of different coal types during pyrolysis, the resulting thermal expansion and contraction properties of blended cokes are more complex, making it difficult to directly predict the agglomeration properties of coke produced from blended coals based on the results of studies on individual coal types. Therefore, directly applying the thermal expansion and contraction research results of a single type of coal to the coking process of blended coal will result in large uncertainties and errors. In order to more accurately predict and control the coke size produced by blended coal, it is necessary to establish a direct relationship between the thermal expansion and contraction of blended coal and the coke size.

[0004] Chinese patent publication number CN118967660A discloses a method for detecting the mechanical strength of coke based on image recognition, which includes obtaining an image of a coke sample, calculating and counting the total pixel diameter and total number of the coke sample before and after the test, counting each coke particle in the range of 60-80 mm and greater than 80 mm in the sample before the test, and calculating the average particle size to obtain the average pixel particle size and the number of coke particles in the range of 60-80 mm and greater than 80 mm, calculating the average pixel particle size and the corresponding number of coke particles in the range of 10-20 mm, 20-40 mm, 40-60 mm, 60-80 mm and greater than 80 mm after the test, calculating the proportion of coke pixel area in each particle size range, establishing wear resistance indexes Ar1 to Ar3, establishing anti-crushing indexes Rc1 to Rc2, and establishing a comprehensive mechanical strength index; however, the patent does not consider the influence of thermal expansion and contraction on the size of coke.

[0005] Chinese patent publication number CN110591748B discloses a coal blending method for controlling and improving coke particle size. The method comprises the following coal blending percentages by mass: high-volatile coal: ≥30-35%, 1 / 3 coking coal #2: ≤20%, coking coal #1: ≥20%, coking coal #2: ≤30%, and lean coal: 10-18%. The high-volatile coal includes gas coal, fat coal, and 1 / 3 coking coal #1. The blended coal has a volatile matter (Vdaf) value of <28%, a fineness of 70-80%, and a caking index (G) of 80-83. This coal blending method can effectively control the coke particle size on the basis of achieving a high-volatile coking coal usage of more than 30%, wherein the average coke particle size is 50-55mm, and the particle size of 40-80mm is ≥65%, and the particle size ≤25mm is less than 5%, meeting the production needs of large blast furnaces above 3000m3; however, the patent does not make a prediction on the coke particle size of the blended coal.

[0006] Chinese patent publication number CN104484495B discloses a method for predicting coke particle size, comprising the following steps: 1) calculating the proportion P high of coal with a solid-soft temperature interval of less than 80°C and a volatile content greater than 34%, and the proportion P low of coal with a volatile content less than 20% in the blended coal; 2) measuring the Kiel fluidity of the blended coal to obtain the solid-soft temperature interval ΔT and the Kiel plastic flow area S of the blended coal; 3) setting D = A + B*ΔT + C*lgS + E*P high + F*P low, where D represents the predicted value of the average coke particle size, and A, B, C, E, and F are constants; 4) substituting five sets of coal blending data into a formula to calculate the values ​​of constants A, B, C, E, and F; 5) formulating a coal blending plan, measuring the Kiel fluidity of the blended coal to obtain ΔT and S, and then calculating the D value according to the formula; however, the patent does not consider the influence of the pyrolysis shrinkage coefficient in the blended coal on the agglomeration performance of the coke. Summary of the Invention

[0007] The present application provides a method for quantitatively predicting coke lump size in coking coal mixed with lean coal, which can predict coke lump size in advance according to thermal expansion and contraction of mixed coal in the coking process, help to determine whether it meets the requirements of metallurgical coke, and effectively reduce trial and error cost and time cost, and improve coke production efficiency.

[0008] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0009] A method for quantitatively predicting coke lump size in coking coal mixed with lean coal, which uses the pyrolysis shrinkage coefficient of mixed coal after mixing with lean coal to predict coke lump size, and the mixed coal includes gas coal, 1 / 3 coking coal, fat coal, coking coal and lean coal, and comprises the following steps:

[0010] S1, different types of coal samples are respectively crushed to less than 0.2mm and then mixed to prepare a mixed coal sample;

[0011] S2, prepare a mixed coal pencil according to the test method of the Yoneyama dilatometer, and use a coking coal pyrolysis shrinkage tester to measure the pyrolysis shrinkage curve of the mixed coal sample and calculate the shrinkage coefficient X;

[0012] S3, calculate the average lump size of the coke produced by the mixed coal according to the obtained shrinkage coefficient through a coke lump size prediction formula;

[0013] Y = 71.47-2.54X, (R 2 = 0.959);

[0014] Wherein, Y is the average diameter of coke lump after coking of the mixed coal containing lean coal, mm.

[0015] Further, the gas coal, 1 / 3 coking coal, fat coal, coking coal and lean coal in the mixed coal are recorded as follows in terms of mass percentage: lean coal ratio 5% to 18%, coking coal ratio 46% to 59%, 1 / 3 coking coal ratio 5% to 15%, fat coal ratio 7% to 15%, and gas coal ratio 10% to 18%.

[0016] Further, the coking coal pyrolysis shrinkage tester comprises a displacement sensor, an electric furnace, an expansion tube, a heating wire, a thermocouple and a temperature control and data acquisition device, the electric furnace is a shaft furnace, the expansion tube and the thermocouple are arranged in the hearth of the shaft furnace, the heating wire is arranged on the outer wall of the expansion tube, and the detection end of the thermocouple is inserted into the center position of the sample in the expansion tube;

[0017] The expansion tube comprises a sample tube, a sealing plug and a pressure rod, the bottom of the sample tube is closed, the upper part of the sample tube is provided with the sealing plug, the pressure rod is inserted into the sample tube through the central hole of the sealing plug and is arranged at the upper part of the coal sample, the pressure rod can slide up and down, the bottom of the pressure rod is provided with an exhaust hole, the displacement sensor is connected with the pressure rod to display the high displacement change of the coal sample in the pyrolysis and semi-coke shrinkage stages, the displacement sensor and the thermocouple signal line are connected to the input end of the temperature control and data acquisition device, and the power line of the heating wire is connected to the output end of the temperature control.

[0018] Further, the test conditions of the coking coal pyrolysis shrinkage tester are as follows: the final test temperature is 800-950 DEG C, the temperature rising process during the test is as follows: room temperature to 250-350 DEG C, the temperature rising rate is 5 DEG C per minute -1 -7 DEG C per minute -1 ; 350-950 DEG C, the temperature rising rate is 2 DEG C per minute -1 -3 DEG C per minute -1 ; the final test temperature to room temperature, and the power is turned off for natural cooling.

[0019] Compared with the prior art, the beneficial effects of the present application are as follows:

[0020] 1) The lean coal is added to the mixed coal to help improve the bulk density of the coked coke, but the amount of lean coal added has no quantitative relationship with the average bulk density of the coke, the lean coal is added to the mixed coal based on the industrial coal blending ratio, and thus the relationship between the shrinkage coefficient X of the mixed coal after adding the lean coal and the average diameter Y of the coke block is established, and the coking experiment is carried out in an industrial coke oven, so that the present application is closer to the actual situation.

[0021] 2) In the aspect of establishing the relationship between the shrinkage coefficient and the coke bulk density, the prior art usually uses different metamorphic degree coals to obtain the shrinkage coefficient and the coke bulk density data, and the present application obtains the shrinkage coefficient and the coke bulk density data by using the lean coal, and thus the fitting degree of the relationship established is higher.

[0022] 3) The relationship between the shrinkage coefficient and the coke bulk density established by the present application has higher accuracy and precision, can predict the coke bulk density of the mixed coal with the lean coal, improves the coking production efficiency of the coal blending and coking enterprise, and provides strong support for the sustainable development of the steel industry. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a coking coal pyrolysis expansion and shrinkage schematic diagram.

[0024] Figure 2 It is a coking coal pyrolysis shrinkage tester structural schematic diagram.

[0025] Figure 3 It is an expansion tube structural schematic diagram.

[0026] Figure: 1, displacement sensor; 2, electric furnace; 3, expansion tube; 4, sample; 5, heating wire; 6, thermocouple; 7, temperature control and data acquisition device; 8, pressure rod; 9, blocking center hole; 10, blocking; 11, sample tube; 12, exhaust hole. DETAILED DESCRIPTION

[0027] The specific embodiments of the present application will be further described below in conjunction with the accompanying drawings:

[0028] See Figure 2 , the structural schematic diagram of the present application. The present application is a method for quantitatively predicting coke lump size in coking coal with lean coal, which uses the shrinkage coefficient of the blended coal after blending with lean coal to predict the coke lump size. The blended coal includes gas coal, 1 / 3 coking coal, fat coal, coking coal and lean coal, and includes the following steps:

[0029] S1, different types of coal samples are respectively crushed to less than 0.2mm, and then mixed together according to a certain proportion to make a blended coal sample. The mass percentage of gas coal, 1 / 3 coking coal, fat coal, coking coal and lean coal in the blended coal is as follows: lean coal ratio 5% to 18%, coking coal ratio 46% to 59%, 1 / 3 coking coal ratio 5% to 15%, fat coal ratio 7% to 15%, and gas coal ratio 10% to 18%.

[0030] S2, prepare a blended coal pencil according to the test method of the Yanyan dilatometer for bituminous coal, and use a coking coal pyrolysis shrinkage tester to measure the pyrolysis shrinkage curve of the blended coal sample and calculate the shrinkage coefficient X. The shrinkage coefficient X is calculated as follows:

[0031]

[0032] Wherein, L0 is the initial length of the gelatinous body after solidification, mm;

[0033] △L is the change value of the gelatinous body after solidification, mm;

[0034] △T is the unit temperature interval, ℃.

[0035] S3, according to the obtained shrinkage coefficient, calculate the average lump size of the coking coal blended with the blended coal through the coke lump size prediction formula;

[0036] Y = 71.47 - 2.54X, (R 2 = 0.959);

[0037] Wherein, R 2 The closer to 1, the higher the correlation, indicating the correlation between X and Y, Y represents the average diameter of the coke lump after coking of the blended coal containing 5% to 18% lean coal, mm; X represents the shrinkage coefficient of the blended coal, 10 -4 ℃ -1 .

[0038] See Figure 2 , the coking coal pyrolysis shrinkage tester includes displacement sensor 1, electric furnace 2, expansion tube 3, heating wire 5, thermocouple 6 and temperature control and data acquisition device 7, the electric furnace 2 is a well-type furnace, expansion tube 3 and thermocouple 6 are arranged in the well-type furnace hearth of electric furnace 2, heating wire 5 is arranged on the outer wall of expansion tube 3, the head of the thermocouple 6 is placed in the center position of the sample area along the height, and the heating circuit outside the hearth is heated by heating wire 5, so that the sample 4 in the expansion tube 3 is heated along the specified heating rate;

[0039] See Figure 3 , the expansion tube 3 includes sample tube 11, plugging 10 and pressure rod 8, the bottom of the sample tube 11 is closed, the inner diameter of the sample tube 11 is 10 mm, the bottom is closed, the coal sample is loaded in the bottom of the inner tube with a height of 60 mm, the pressure rod 8 is placed on the upper part of the coal sample, the bottom of the pressure rod 8 has an exhaust hole 12, the upper part of the sample tube 11 has plugging 10, the center of the plugging has a hole, the pressure rod 8 passes through the center hole 9 of the plugging and can slide up and down freely, the displacement sensor 1 is connected to the pressure rod 8 to display the vertical displacement change of the coal sample during pyrolysis and semi-coke shrinkage stage, the signal lines of the displacement sensor 1 and the thermocouple 6 are connected to the input end of the temperature control and data acquisition device 7, and the power line of the heating wire 5 is connected to the output end of the temperature control.

[0040] The test conditions of the coking coal pyrolysis shrinkage tester are as follows: Figure 1 The final test temperature is 850 DEG C, and the heating process during the test is as follows: room temperature to 300 DEG C, the heating rate is 7 DEG C·min -1 ; 300-850 DEG C, the heating rate is 2 DEG C·min -1 ; the final test temperature to room temperature, and the power is turned off for natural cooling.

[0041] The operation process of the coking coal pyrolysis shrinkage tester is as follows: the coal sample 4 is loaded into the sample tube 11, the pressure rod 8 is pressed, the plugging 10 is covered, the pressure rod 8 passes through the center hole 9 of the plugging, the expansion tube 3 is placed into the hearth, the displacement sensor 1 is connected, the heating wire 5 is started to heat the electric furnace 2, the vertical displacement change of the sample 4 is recorded by the temperature control and data acquisition device 7 during the heating process of the coal sample, finally, the semi-coke shrinkage coefficient is calculated according to the shrinkage coefficient formula, and the average bulk density of the coking coal of the blending coal is calculated through the coking bulk density prediction formula according to the obtained shrinkage coefficient.

[0042] The following examples are implemented on the premise of the technical scheme of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following examples. The methods used in the following examples are all conventional methods unless otherwise specified.

[0043]

EXAMPLE

[0044] The ratio range of the gas coal, 1 / 3 coking coal, fat coal, coking coal and lean coal in the technical scheme is used for coal blending coking, and the properties of each single coal used for the coal blending coking are shown in table 1, and the specific coal blending scheme is shown in table 2.

[0045] Table 1: industrial analysis, total sulfur, oya expansion degree, gum layer index and bonding index of the coal used for coal blending

[0046]

[0047]

[0048] wherein, * is obtained by difference method.

[0049] Table 2: coal blending scheme of examples 1, 2, 3 and 4

[0050]

[0051] Table 3 shows that, in each example, the average value of coke bulk density predicted by shrinkage coefficient and the relationship Y = 71.47-2.54X, (R 2 = 0.959) is close to the measured value, and the maximum error is 3.04%.

[0052] Table 3: comparison of predicted value and measured value of coke bulk density of different coal blending schemes

[0053]

Claims

1. A method for quantitatively predicting the size of coke by adding lean coal to coking coal, characterized in that: The coke size is predicted using the pyrolysis shrinkage coefficient of the blended coal after blending with lean coal. The blended coal includes gas coal, 1 / 3 coking coal, fat coal, coking coal and lean coal, and includes the following steps: S1. Grind different types of coal samples into smaller pieces than 0.2 mm and mix them to prepare blended coal samples; S2. Prepare a blended coal pen according to the bituminous coal Oya dilatometer test method, measure the pyrolysis shrinkage curve of the blended coal sample using a coking coal pyrolysis shrinkage tester, and calculate the shrinkage coefficient X; S3. Calculate the average coke size of the coke produced by the blended coal using the coke size prediction formula based on the obtained shrinkage coefficient; Y=71.47-2.54X,(R 2 =0.959); Wherein, Y is the average diameter of the coke block after coking of the lean coal in the blended coal, mm.

2. The method for quantitatively predicting the coke size by adding lean coal to coking coal according to claim 1, characterized in that: The gas coal, 1 / 3 coking coal, fat coal, coking coal and lean coal are recorded in the mixed coal in percentage by mass as follows: lean coal ratio 5% to 18%, coking coal ratio 46% to 59%, 1 / 3 coking coal ratio 5% to 15%, fat coal ratio 7% to 15%, and gas coal ratio 10% to 18%.

3. The method for quantitatively predicting the coke size by adding lean coal to coking coal according to claim 1, characterized in that: The coking coal pyrolysis shrinkage measuring instrument includes a displacement sensor, an electric furnace, an expansion tube, a heating wire, a thermocouple, and a temperature control and data acquisition device. The electric furnace is a pit-type furnace. An expansion tube and a thermocouple are arranged in the furnace of the pit-type furnace. A heating wire is arranged on the outer wall of the expansion tube. The detection end of the thermocouple is inserted into the center position of the sample in the expansion tube. The expansion tube includes a sample tube, a plug and a pressure rod. The bottom of the sample tube is closed, and a plug is provided on the upper part of the sample tube. The pressure rod passes through the central hole of the plug and is inserted into the sample tube and is arranged on the upper part of the coal sample. The pressure rod can slide up and down, and an exhaust hole is provided at the bottom of the pressure rod. The displacement sensor is connected to the pressure rod to display the high-direction displacement changes of the coal sample during the pyrolysis and semi-coke shrinkage stages. The displacement sensor and the thermocouple signal line are connected to the input end of the temperature control and data acquisition device, and the power line of the heating wire is connected to the output end of the temperature control.

4. The method for quantitatively predicting the coke size by adding lean coal to coking coal according to claim 1, characterized in that: The test conditions of the coking coal pyrolysis shrinkage tester are as follows: the final test temperature is 800℃~950℃, the temperature rise process is from room temperature to 250℃~350℃, and the heating rate is 5℃·min -1 ~7℃·min -1 ; 350~950℃, heating rate 2℃·min -1 ~3℃·min -1 ; When the final test temperature reaches room temperature, turn off the power and let the temperature cool down naturally.

Images