Method for characterizing coking performance of coking coal and application in coal blending for coking

Abstract

The application discloses a method for establishing coking performance of coking coal, which comprises the following steps: 1) performing Giesler fluidity determination on target coking coal to obtain a Giesler fluidity curve of the target coking coal; 2) performing integration on the curve, intercepting a curve area between 465 DEG C and a solidification temperature of the target coking coal, and setting the area as F; 3) representing the coking performance of the target coking coal by the F value, the greater the F value, the better the coking performance of the target coking coal, and 31) if F>500 dd, the coking coal is determined as type I coking coal or high-quality coking coal; 32) if F<=500 dd, the coking coal is determined as type II coking coal or medium or poor-quality coking coal. The application further discloses application of the method in coal blending and coking. The Giesler fluidity curve of the coking coal is integrated with respect to temperature, the curve area between 465 DEG C and the solidification temperature of the coking coal is intercepted, the coking performance of the coal sample is evaluated according to the area, and the coal blending and coking are correspondingly performed, so that the high-quality coking coal is reasonably used, and the coal blending cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of coal blending and coking technology, specifically relating to a method for establishing a characterization of the coking properties of coking coal and its application in coal blending and coking. Background Technology

[0002] Coking coal is the foundational coal type supporting coke strength, and its price is higher than other coal types. To control blending costs, coking enterprises are constantly exploring ways to ensure that coke quality meets the minimum blending ratio of high-priced coking coal under normal blast furnace operation conditions. In recent years, many enterprises have begun to blend some low-priced, high-sulfur, lean coking coal with sulfur content of 2.0-3.0% and volatile matter below 26%. Besides its higher sulfur content and lower volatile matter, this type of coal generally has a G value between 70 and 85. According to the general understanding of those skilled in the art, although this type of coking coal has a lower volatile matter, its G value is also low, and its quality is somewhat different from that of high-quality coking coal. There are also some coking coals with relatively high G values, but also relatively high volatile matter. Based on the general understanding in the field, enterprises usually use them uniformly as low-quality coking coal. How to scientifically determine the quality of coking coal and maximize its cost-reduction effect while ensuring stable coke quality has become the goal of coking workers in steel enterprises. Currently, there is a large body of literature evaluating the quality of coking coal. Some of these studies evaluate coking coal or conduct coking blending based on its Gibbs free flow curve. Relevant literature and patent abstracts are listed below: (1) Patent document with application number CN201410623467.1 and invention title "Coal Blending and Coking Method Based on the Flow Region of the Kierkegaard Flowability Curve" discloses a coal blending and coking method based on the width and flow region of the Kierkegaard flowability curve, including the following steps: 1) measuring the Kierkegaard flowability of coking coal to obtain the flowability corresponding to each temperature point between softening and solidification of coking coal; 2) integrating the curve of the part with a flowability value ≥10000 ddpm over time to obtain the f1 value of the flow region of the coking coal with a flowability ≥10000 ddpm; 3) blending coal according to the range of the f1 value. The present invention, based on a large amount of experimental data statistics, takes the flow region above 10000 ddpm as a characterization value for coking coal with a maximum flowability of 30000 ddpm or more, to measure the flow performance of coking coal in the high flow range. It can use the different values ​​of the flow region to unify the coal blending method for coking coal with normal or abnormal morphology, thereby correctly guiding the coal blending production. This literature mainly focuses on coking coal with high fluidity and is not suitable for coking coal with low fluidity.

[0003] (2) A method for coking coal blending based on flow region (CN201410623581.4). This patent document discloses a method for coking coal blending based on flow region, including the following steps: 1) Measuring the Kierkegaard fluidity of coking coal to obtain the fluidity corresponding to each temperature point between softening and solidification of coking coal; 2) Integrating the curve of the part with fluidity ≥1000 ddpm over time to obtain the flow region of the part with fluidity ≥1000 ddpm of the coking coal, and setting this as the f1 value; 3) Blending coal according to the range of the f1 value. Based on a large amount of experimental data statistics, this invention uses the flow region above 1000 ddpm as a characterization value for coking coal with a maximum fluidity between 1000 ddpm and 30000 ddpm to measure the flow performance of coking coal in the high flow range. The size of the flow region value can be used to uniformly blend coking coal with normal or abnormal morphology, thereby correctly guiding coal blending in production and better ensuring the quality of coke. This literature also mainly focuses on coking coal with high fluidity, and is not suitable for coking coal with low fluidity.

[0004] The common feature of the above patent documents (1) and (2) is that they use the area of ​​the Gibbs freeness curve above a certain instantaneous freeness value as a characterizing value to evaluate the quality of coking coal and guide coal blending.

[0005] (3) A method for blending coal to replace coking coal (CN201010583605.X). This patent document discloses a method for blending coal to replace coking coal, including the following steps: obtaining the caking index, expansion degree, maximum Gibbs flowability, volatile matter, and coking microstructure composition of the coking coal used; determining a first-type substitute coal of medium to low metamorphism with a caking index similar to that of the coking coal used, and with an expansion degree, maximum Gibbs flowability, and volatile matter greater than that of the coking coal used; calculating the substitution ratio of the first-type substitute coal; determining a second-type substitute coal with a coking microstructure composition similar to that of the coking coal used; calculating the substitution ratio of the second-type substitute coal; and substituting the coking coal used according to the combination of the first-type substitute coal and its substitution ratio, and the second-type substitute coal and its substitution ratio. This method can solve the problem of the substitutability of coking coal in coking coal blending, save high-quality coking coal resources, and promote the sustainable development of the coking industry. This document only uses Gibbs flowability as one of the indicators, combining it with other indicators for coal blending. Similarly, this literature only applies to coking coal with high fluidity.

[0006] (4) A method for blending coal for coking using the Gibbs free flow index (CN201010585453.7). This patent document relates to a method for blending coal for coking, and in particular to a method for blending coal for coking using the Gibbs free flow index. It mainly addresses the technical problems of large workload and long experimental cycle in the application of multi-index coal blending, which involves multiple independent variables. The process includes the following steps: First, blending coal according to the following mass percentages: 1 / 3 coking coal 10-15%, gas coal 22-30%, fat coal 20-25%, coking coal 30-38%, and lean coal 0-5%; Second, controlling the quality of the blended coal to achieve an ash content of 9-10%, sulfur content of 0.8-0.9%, a maximum fluidity logarithm of 2.2-3.0, and a Kierkegaard maximum fluidity temperature of 437℃-442℃; Third, crushing the blended coal; Fourth, coking, feeding the crushed blended coal into a coke oven, controlling the coke cake center temperature at 1000±50℃, and the coking time at 19±2 hours; Fifth, cooling after coking and conducting coke quality testing. This literature indirectly controls the proportion of each individual coal type by controlling the maximum fluidity of the blended coal and the Kierkegaard maximum fluidity temperature of 437℃-442℃, thereby controlling the quality of the coke.

[0007] (5) A method for coking coal blending with coking coal (CN201210114006.2). This patent document discloses a method for coking coal blending with coking coal, including the step of blending various single coking coals. The single coking coals include coking coal 1#, gas coking coal, coking coal, and 1 / 3 coking coal. The dry ash-free volatile matter Vdaf of coking coal 1# is <28%, Y value is >25mm, and maximum Gibbs freeness MF is <10000ddpm. The maximum Gibbs freeness MF of gas coking coal is ≥60000ddpm, the Oya expansion b value is ≥220%, the caking index G value of the blended coal is 79-83, the maximum Gibbs freeness is 400-2000ddpm, and the Oya expansion b value is <10%. The coking coal blending method of this invention can make reasonable use of coking coal resources and reduce blending costs. Under conditions without graded crushing, coal moisture conditioning, briquetting, or compaction coking processes, the CSR of coke produced in coke ovens of 6 meters or more is greater than 63%. The method in the literature is only applicable to bituminous coal or gas-bite coal with high fluidity.

[0008] (6) A coal blending method for preparing high-activity and high-strength coke (CN201010515591.8). This patent document discloses a coal blending method for preparing high-activity and high-strength coke, including the step of blending coking coals participating in the blending. By weight percentage, the coking coals participating in the blending include 20-70% Xinjiang strong caking coal, and the remainder is one or more combinations of coking coal, lean coal, fat coal, gas coal, and 1 / 3 coking coal. After blending, the following conditions are met: air-dried moisture 1.0-1.7%, dry ash 8-12%, dry volatile matter 22-26%, sulfur <0.6%, caking index 82-100, maximum Gibbs freeness 1.9-3.0, average vitrinite reflectance 1.1-1.4%, and the dry ash content of CaO 10-15%, Fe2O3 9-15%, and MgO 3-5%. This invention effectively utilizes a highly caking coal, leveraging its advantages of strong caking properties, low ash, low sulfur, and low cost and availability to produce high-activity, high-strength coke for blast furnace use at low cost. This literature also indirectly controls the proportion of each individual coal type by controlling the maximum fluidity of the blended coal in combination with other indicators, thereby controlling the quality of the coke.

[0009] (7) Evaluation method for coking coal quality with maximum Gibbs freeness ≤ 2000 ddpm (CN201310228678.0). This patent document discloses an evaluation method for coking coal quality with maximum Gibbs freeness MF ≤ 2000 ddpm. It obtains the proportion of coarse-grained mosaic structure X1, the sum of the proportions of fibrous and lamellar structures X2, the maximum Gibbs freeness MF, and the expansion degree b by testing the coking coal, and correlates them to characterize the quality of coking coal. This document involves a large number of technical indicators and is only effective for coking coal with low sulfur content and low freeness.

[0010] (8) Evaluation method for coking coal quality with maximum Gibbs freeness > 2000 ddpm (CN201310228754.8). This patent document discloses an evaluation method for coking coal quality with maximum Gibbs freeness MF > 2000 ddpm. It obtains the proportion of coarse-grained mosaic structure X1, the sum of the proportions of fibrous and lamellar structures X2, the maximum Gibbs freeness MF, and the expansion degree b by testing the coking coal, and correlates them to characterize the quality of coking coal. This document involves a large number of technical indicators and is only effective for coking coal with low sulfur content and high fluidity.

[0011] (9) Evaluation method of coarse coal quality (CN201310228936.5) This patent document discloses an evaluation method of coarse coal quality. By detecting the key indicators of coarse coal quality, the proportion of coarse-grained mosaic structure X, the maximum Gibbs flowability MF and the expansion degree b are obtained, and they are correlated to characterize the quality of coarse coal.

[0012] None of the aforementioned patent documents can adequately evaluate and determine the quality of coking coal with low volatile matter, low, or medium G-value. Summary of the Invention

[0013] The first technical problem to be solved by the present invention is to provide a method for characterizing the coking properties of coking coal, so as to accurately determine the coking properties of coking coal according to the method, and thus rationally blend it to achieve the purpose of reducing the blending of high-priced coal types and / or reducing the cost of coal blending while stabilizing the quality of coke.

[0014] The second technical problem to be solved by the present invention is to rationally blend coking coal according to the above characterization method.

[0015] To solve the first technical problem mentioned above, the technical solution provided by the present invention includes the following steps: (1) The Gibbs flowability of the target coking coal was measured to obtain the Gibbs flowability curve of the target coking coal.

[0016] (2) Integrate the curve and extract the area between 465℃ and the target coking coal solidification temperature, and set the area as F.

[0017] (3) The coking performance of the target coking coal is characterized by the F value. The larger the F value, the better the coking performance of the target coking coal, and: (31) If F > 500dd, the coking coal is determined to be Class I coking coal or high-quality coking coal. This type of coking coal is the basic coal type that supports the strength of coke.

[0018] (32) If F≤500dd, the coking coal is determined to be Class II coking coal or medium-low quality coking coal. The quality of this type of coking coal is poor and it cannot serve as a good coke skeleton to support the strength of the coke.

[0019] Preferably, the coking coal has a volatile matter content of 19-26% and a G value of 70-85.

[0020] Preferably, the sulfur content of the coking coal is 2.0 to 3.0%.

[0021] To solve the second technical problem mentioned above, the present invention adopts the following technical solution: (1) If F > 500dd, the coking coal is determined to be Class I coking coal or high-quality coking coal, and the blending range of this type of coking coal is ≥ 30%.

[0022] (2) If F≤500dd, the coking coal is determined to be Class II coking coal or medium-low quality coking coal, and the blending range of this type of coking coal is ≤15%.

[0023] Through extensive research, the inventors of this invention discovered that the Kierkegaard flowability curve of high-sulfur coking coal possesses unique properties. The Kierkegaard flowability value decreases less rapidly with increasing temperature compared to low-sulfur coking coal, indicating that the activity of the colloid in high-sulfur coking coal is superior to that in low-sulfur coking coal at high temperatures. Further research revealed that regardless of sulfur content, integrating the Kierkegaard flowability curve of coking coal with respect to temperature and extracting the area between 465°C and the coking temperature of the coking coal, if this area (F) > 500dd, indicates that the coking coal possesses superior quality and can effectively support the coke skeleton. Based on these findings, this invention utilizes the Kierkegaard flowability measurement method to assess the coking performance of coking coal during the coking process by evaluating the activity of the colloid in the high-temperature range, and accordingly blends coking coal. In particular, it can further differentiate coking coal with volatile matter content of 19-22% and a G value of 70-86, which is generally considered low- or medium-quality coking coal, thereby achieving the goal of rationally blending high-quality coking coal and reducing blending costs. Attached Figure Description

[0024] Figure 1 This is a graph of the Gibbs flowability of the present invention (the shaded area is the area obtained by integrating the Gibbs flowability with respect to the curing temperature).

[0025] Figure 2 The CSR of the coke obtained from the coal blending schemes in Examples 1-14 is based on the A and B content of coking coal.

[0026] Figure 3 The CSR of the coke obtained from the coal blending schemes in Examples 1-14 is based on the C and D content of coking coal. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] The technical solution of the present invention includes the following steps: (1) Select the target coking coal and measure its Gibbs flowability to obtain the Gibbs flowability curve of the target coking coal.

[0029] (2) Integrate the curve and calculate the area F of the Gibbs free flow curve in the portion above 465℃ and below the curing temperature (e.g., Figure 1 As shown in the figure, its quality level is determined based on the magnitude of the F value.

[0030] (3) If F > 500dd, the coking coal is determined to be Class I coking coal or high-quality coking coal, which is the basic coal type supporting coke strength, and the proportion range is ≥30%; if F ≤ 500dd, the coking coal is determined to be Class II coking coal or low-quality coking coal, and the proportion range is ≤15%.

[0031] Example (1) Select coking coal A, coking coal B, coking coal C and coking coal D for Gibbs fluidity determination.

[0032] (2) The obtained Gibbs flow curve was analyzed, and the area of ​​the flow curve between the softening temperature of 465℃ and its curing temperature was calculated. The data are shown in Table 1.

[0033] Table 1. Areas of Gibbs free flowability curves and physical properties of various coking coals above 465℃ (3) According to the method of the present invention, coking coal A and coking coal B are Class I coking coals, and coking coal C and D are Class II coking coals.

[0034] (4) Under the same conditions of quality and proportion of other coal types, conduct a 2kg small coke oven coal blending and coking test according to the following proportion and determine the coke CSR.

[0035] Table 2 Coal blending schemes for Examples 1-14 The thermal properties of the coke produced by each scheme in Examples 1-14 were measured, and the data are shown in [the table below]. Figure 2 , 3 .

[0036] from Figure 2 , Figure 3 As shown in Table 2, when the content of coking coal A and coking coal B, which are classified as Class I coking coal according to the method of the present invention, is less than 30%, the coke CSR decreases significantly. When the content of coking coal C and coking coal D, which are classified as Class II coking coal according to the method of the present invention is less than 15%, the coke CSR decreases, but the decrease is small. When the content exceeds 15%, the CSR decreases significantly. Although the G value and volatile matter of coking coal C are similar to those of coking coal A, the area of ​​its Gibbs freeness curve above 465℃ is 209dd, which is significantly lower than that of coking coal A (674dd). This indicates that the thermal stability of the colloidal body of coking coal C is lower in the high-temperature range. Under the same proportion, the coke strength of coking coal A is significantly higher than that of coking coal C.

Claims

1. A method for establishing a characterization of the coking properties of coking coal, characterized in that, The method includes the following steps: 1) The Gibbs flowability of the target coking coal was measured to obtain the Gibbs flowability curve of the target coking coal; 2) Integrate the curve, extract the area between 465℃ and the target coking coal solidification temperature, and set this area as F; 3) The coking performance of the target coking coal is characterized by the F-value. The higher the F-value, the better the coking performance of the target coking coal, and: 31) If F > 500dd, then the coking coal is determined to be Class I coking coal or high-quality coking coal; 32) If F≤500dd, then the coking coal is determined to be Class II coking coal or medium-to-low quality coking coal.

2. The method for establishing characterization of coking properties of coking coal according to claim 1, characterized in that, The coking coal has a volatile matter content of 19-26% and a G value of 70-85.

3. The method for establishing characterization of coking properties of coking coal according to claim 1 or 2, characterized in that, The sulfur content of the coking coal is 2.0% to 3.0%.

4. The application of the method according to any one of claims 1 to 3 in coal blending and coking, characterized in that: 1) If F > 500dd, then the blending range of this type of coking coal is ≥ 30%; 2) If F≤500dd, then the blending range of this type of coking coal is ≤15%.

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