Method for improving coke granularity and application thereof

Abstract

The invention relates to a method for improving the granularity of coke and application thereof, raw materials are subjected to coal blending and coking according to the proportion of 46-59% of coking coal, 9-16% of 1 / 3 coking coal, 15-25% of fat coal, 5-15% of gas coal and 5-8% of lean coal in total 100% to obtain coke, the raw materials comprise gas coal, 1 / 3 coking coal, fat coal, coking coal and lean coal, the lean coal further comprises specific lean coal, and the content of the specific lean coal is 0-14%; the ash composition and vitrinite average reflectivity of the specific lean coal are as follows: MgO is less than 2%, Fe2O3 is less than 3%, CaO is less than 3%, K2O is less than 4%, and Na2O is less than 1%, and is 1.72-1.82%. The content of each raw material Mad is 0.7-1.9 wt.%, the ash content Ad is 7.9-10.5 wt.%, the volatile component Vdaf is 19-37.5 wt.%, the Audible shrinkage degree a is 23-28.5%, the Audible expansion degree b is-2-145%, the thickness Y of a gelatinous layer is 8-24.5 mm, the shrinkage degree X of the gelatinous layer is 5-43.5 mm, and the caking index G is 40-95. According to the method, specific lean coal with relatively low content of MgO, Fe2O3, CaO, K2O and Na2O is added, and the moisture of the mixed coal is adjusted, so that the granularity uniformity of the coke and the air permeability of the blast furnace are improved, and the cold strength and the thermal property of the coke are ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgy and coking coal blending, and particularly relates to a method for improving coke particle size and application thereof. BACKGROUND

[0002] The development and utilization of large-scale blast furnaces, increased coal injection ratio, and hydrogen-rich raw materials have put forward higher requirements for the performance of coke, especially under the background of prolonged residence time in blast furnaces and significantly reduced coke ratio, the block size of coke has become an important consideration factor.

[0003] Larger coke block size helps to improve the permeability of the blast furnace and the skeleton effect of the coke, reduces the crushing and pulverization of the coke, thereby improving the utilization coefficient of the blast furnace and reducing the coke ratio. Therefore, how to control and optimize the block size of the coke has become an important problem to be solved in the steel industry. Existing literature has conducted in-depth research on the influence of thermal expansion and contraction of single coking coal on the block size of the coke made from single coking coal. The shrinkage characteristics of coking coal with different metamorphic degrees in the pyrolysis process are studied by using an improved Oya dilatometer, and the results show that the pyrolysis shrinkage coefficient has a significant influence on the blocking performance of the coke. However, these studies mainly focus on single coking coal, and there is no systematic and in-depth research on the case of multiple coal blending for coking which is widely used in actual production. In actual coking process, in order to reduce the cost and improve the quality of coke, multiple coking coals with different properties are often blended for coking. In this paper, specific lean coal is added to the blended coal, and the water content of the blended coal is adjusted to shorten the coking time, which not only reduces the cost of coal blending but also improves the average particle size of the coke. Under the premise of ensuring the quality of the coke, the production efficiency of the coking plant is improved.

[0004] CN110591748B discloses a coal blending method for controlling and improving coke particle size, specifically, each coal type is blended according to the following mass percentage: high-volatile coal: ≥30-35%, 1 / 3 coking coal 2#: ≤20%, coking coal 1#: ≥20%, coking coal 2#: ≤30%, lean coal: 10-18%. Among them, the high-volatile coal includes gas coal, fat coal and 1 / 3 coking coal 1#, the blended coal prepared from each coal type has a volatile matter Vdafblended coal<28%, a fineness of 70-80%, and a caking index Gblended coalof 80-83, and the amount of high-volatile coking coal is more than 30%, thereby effectively controlling the coke particle size. However, the coke blocking performance is not disclosed in this scheme.

[0005] CN103194249 A discloses a coking coal blending method for reducing coke particle size, comprising the following steps: 1) determining the gel layer index of the adjusting coal, obtaining the final shrinkage X, observing the gel layer volume curve; blending the adjusting coal with a final shrinkage X>35mm, or blending the adjusting coal with a final shrinkage 35>=X>28mm and a gel layer volume curve in the shape of "Z", and the adjusting coal accounts for 25~40% by weight, the adjusting coal is gas coal and 1 / 3 coking coal, and the gas coal accounts for 0~10% by weight; 2) blending other single coal, so that the sum of gas fat coal and fat coal accounts for 8~15% by weight, coking coal accounts for 32~42% by weight, and lean coal accounts for 5~13% by weight, the technical solution has the problems of limited coal adjusting range and difficult industrial implementation.

[0006] Liu Yang et al. in "Influence of pyrolysis shrinkage characteristics of coking coal on coke lumping performance" discloses that the pyrolysis shrinkage performance of coking coal is a key factor to determine the coke lumping performance, and the pyrolysis shrinkage activation energy is also well associated with the average coke lump size, therefore, the average coke lump size of coking coal with different metamorphic degrees can be effectively predicted by the pyrolysis shrinkage coefficient and shrinkage activation energy.

[0007] At present, the improvement method of coke particle size has the problems of small average diameter of coke, reduced cold strength and thermal properties due to the excessive content of alkali metal in lean ash, and the average coke lump size cannot be predicted by the pyrolysis shrinkage coefficient and shrinkage activation energy, and a method for quantitatively improving coke particle size by blending lean coal in coking coal and its application in predicting coke particle size are proposed. SUMMARY

[0008] To solve the above technical problems, the technical solution adopted by the present application improves the particle size of coke by blending more lean coal in the blending coal and increasing the coking speed. This method can reduce the blending cost by blending more lean coal, reduce the water content of the blending coal, improve the coking speed, improve the coke production efficiency, and provide strong support for the sustainable development of the steel industry.

[0009] According to one aspect of the present application, a method for improving coke particle size is provided, characterized in that the method comprises the following steps: blending raw materials according to the blending ratio to coking, obtaining coke, the raw materials comprising gas coal, 1 / 3 coking coal, fat coal, coking coal and lean coal, the lean coal further comprising specific lean coal, the content of the specific lean coal being 0~14%; The specific lean coal further comprises specific lean coal, and the ash composition and vitrinite average reflectance of the specific lean coal are as follows: MgO<2%, Fe2O3<3%, CaO<3%, K2O<4%, Na2O<1%, and the vitrinite average reflectance is 1.72%~1.82%.

[0010] Further, the air dry basis moisture Mad of each raw material is 0.7-1.9wt.%, the ash content Ad is 7.9-10.5wt.%, the volatile content Vdaf is 19.0-37.5wt.%, the Oya shrinkage a is 23.0-28.5%, the Oya expansion b is -2.0-145%, the gel layer thickness Y is 8.0-24.5mm, the gel layer shrinkage X is 5.0-43.5mm, and the caking index G is 40-95.

[0011] Further, the proportion of the raw materials is as follows: the proportion of coking coal is 46-59%, the proportion of 1 / 3 coking coal is 9-16%, the proportion of fat coal is 15-25%, the proportion of gas coal is 5-15%, and the proportion of lean coal is 5-8%, based on 100%.

[0012] Further, the moisture of the blended coal is 7-9%; The coking conditions are as follows: The coking temperature is 950-1000℃; The coking time is 12-20h.

[0013] Further, the average diameter of the coke is 55-58mm, the crush strength M 40 is 78-81%, the abrasion strength M 10 is 6.5-8.8%, the reactivity index CRI is 23.0-24.5%, and the strength after reaction CSR is 65.0-68.5%.

[0014] According to another aspect of the present application, there is provided a method for improving the coke particle size and the application of the method in coke particle size prediction, and the specific prediction steps are as follows: taking the expression of the relationship between the average diameter of coke and the content of specific lean coal as the prediction formula of coke particle size, the formula of the coke particle size prediction is = -0.0203ω 2 +0.425ω+55.8, wherein represents the average diameter of coke particle size, and ω represents the content of specific lean coal, wherein ω is less than 14%.

[0015] Further, the error of the predicted coke particle size is <1.5%.

[0016] Compared with the prior art, the present application has the following beneficial effects: (1) The technical solution disclosed by the present application improves the coking speed by adding specific lean coal with low contents of MgO, Fe2O3, CaO, K2O and Na2O into the existing coking production technology and adjusting the moisture of the blended coal.

[0017] (2) The technical scheme disclosed by the present application can reduce the coal blending cost, improve the uniformity of coke particle size, ensure the coke cold strength and thermal properties, and is beneficial to improving the blast furnace permeability.

[0018] (3) The technical scheme disclosed by the present application can predict the coke particle size, and the prediction accuracy is high, which can directly guide the production. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The coke physical map prepared by example 1 of the present application. DETAILED DESCRIPTION

[0020] The present application will be further described below in combination with specific examples, but the present application is not limited in any way by the examples.

[0021] Unless otherwise specified, the coal used in the present application is purchased.

[0022] The present application provides a method for improving coke particle size in the specific embodiment part, and the method comprises the following steps: blending and coking raw materials in a blending ratio of 46-59% of coking coal, 9-16% of 1 / 3 coking coal, 15-25% of fat coal, 5-15% of gas coal, and 5-8% of lean coal, so as to obtain coke, wherein the total is 100%, the raw materials comprise gas coal, 1 / 3 coking coal, fat coal, coking coal and lean coal, the lean coal further comprises specific lean coal, the content of the specific lean coal is 0-14%, and the ash composition and average reflectivity of vitrinite of the specific lean coal are as follows: MgO < 2%, Fe2O3 < 3%, CaO < 3%, K2O < 4%, Na2O < 1%, SiO2 < 70%, Al2O3 < 20%, TiO2 < 0.5%, and the total of the above-mentioned components is 100%. The average reflectivity of vitrinite is 1.72%-1.82%.

[0023] Based on the above technical scheme, the air-dried basis moisture M ad of each raw material is 0.7-1.9wt.%, the ash content A d is 7.9-10.5wt.%, the volatile matter V daf is 19.0-37.5wt.%, the Oya shrinkage a is 23.0-28.5%, the Oya expansion b is -2.0-145%, the gel layer thickness Y is 8.0-24.5mm, the gel layer shrinkage X is 5.0-43.5mm, and the caking index G is 40-95.

[0024] Based on the above technical scheme, the moisture of the blended coal is 7-9%.

[0025] Based on the above technical scheme, the coking conditions are as follows: The temperature of the coking is 950-1000℃; The time of the coking is 12-20h.

[0026] Based on the above technical scheme, the average diameter of the coke is 55-58mm, the crushing strength M 40 is 78-81%, the abrasion resistance M 10 is 6.5-8.8%, the reactivity index CRI is 23.0-24.5%, and the strength after reaction CSR is 65.0-68.5%.

[0027] The present application also provides a method for improving the coke particle size in the specific implementation manner, and the application of the method in the coke particle size prediction. The specific prediction steps are as follows: taking the expression of the relationship between the average diameter of the coke and the content of the specific lean coal as the prediction formula of the coke particle size, the formula of the coke particle size prediction is = -0.0203ω 2 + 0.425ω + 55.8, wherein the average diameter of the coke particle size represents the average diameter of the coke, and ω represents the content of the specific lean coal, wherein ω is less than 14%.

[0028] Based on the above technical scheme, the error of the predicted coke particle size is less than 1.5%.

[0029] Embodiments The property-related parameters of each single coal used in embodiments 1-5 are shown in Table 1, wherein the ash composition and the average reflectance of the vitrinite group of the specific lean coal are shown in Table 2, and the coal blending scheme is shown in Table 3. The coal blending is coked at 960℃ for 15h to obtain coke, and the average diameter, cold strength and thermal properties of the coke are shown in Table 4. Taking the expression of the relationship between the average diameter of the coke and the content of the specific lean coal in embodiments 1-4 as the prediction formula of the coke particle size, the formula of the coke particle size prediction is = -0.0203ω 2 + 0.425ω + 55.8, wherein the average diameter of the coke particle size represents the average diameter of the coke, and ω represents the content of the specific lean coal, wherein ω is less than 14%, and the specific prediction condition is shown in Table 4. The error of the predicted coke particle size is less than 1.5%. The actual coke obtained in embodiment 1 is shown in Figure 1 .

[0030] Table 1 shows the property-related parameters of the single coal in embodiments 1-5 .

[0031] Table 2 shows the ash composition and the average reflectance of the vitrinite group of the specific lean coal in embodiments 1-5 .

[0032] Table 3 shows the coal blending scheme in embodiments 1-5 .

[0033] Table 4 is the average diameter, cold strength, thermal properties, prediction of coke of examples 1~5 .

[0034] In summary, by the above technical scheme, the coke average diameter 55~59.6mm, the anti-crushing strength M 40 78.7~81.3%, the abrasion resistance M 10 6.0~8.6%, the reactivity index CRI is 22.9~26.9%, the strength CSR after reaction is 64.4~68.4%, the specific lean coal coke is matched with a proper amount, each index is improved, the coke quality is improved, the coal blending cost is reduced, and the average diameter of the coke can be predicted.

[0035] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical scheme of the present application, which is equivalent to equivalent embodiments, and belongs to the scope of the technical scheme.

Claims

1. A method for improving coke particle size, characterized in that: The method comprises the following steps: blending raw materials according to a ratio of 46-59% coking coal, 9-16% of 1 / 3 coking coal, 15-25% of fat coal, 5-15% of gas coal, and 5-8% of lean coal, with the total being 100%, to obtain coke, wherein the raw materials include gas coal, 1 / 3 coking coal, fat coal, coking coal, and lean coal, and the lean coal further includes specific lean coal, and the content of the specific lean coal is 0-14%; The ash composition and average reflectance of the vitrinite of the specific lean coal are as follows: MgO < 2%, Fe2O3 < 3%, CaO < 3%, K2O < 4%, Na2O < 1%, It is 1.72%~1.82%.

2. The method according to claim 1, characterized in that The air-dried basis moisture content Mad of the raw materials is 0.7~1.9wt.%, the ash content Ad is 7.9~10.5wt.%, the volatile matter Vdaf is 19.0~37.5wt.%, the Oya shrinkage a is 23.0~28.5%, the Oya expansion b is -2.0~145%, the gelatin layer thickness Y is 8.0~24.5mm, the gelatin layer shrinkage X is 5.0~43.5mm, and the bonding index G is 40~95.

3. The method according to claim 1, characterized in that The moisture content of the blended coal is 7-9%; The coking conditions are as follows: The coking temperature is 950-1000°C; The coking time is 12 to 20 hours.

4. The method according to claim 1, wherein The average diameter of the coke is 55-58 mm, the crushing strength M 40 78~81%, wear resistance M 10 The reactivity index CRI is 23.0~24.5%, and the post-reaction strength CSR is 65.0~68.5%.

5. An application of the method for improving coke particle size according to any one of claims 1 to 4 in coke particle size prediction, characterized in that: The specific prediction steps are as follows: The relationship between the average diameter of coke and the specific lean coal content is used as the prediction formula for coke particle size. The formula for coke particle size prediction is: = -0.0203ω 2 +0.425ω+55.8, where represents the average diameter of coke particles, and ω represents the content of specific lean coal, where ω is less than 14%.

6. The use according to claim 5, characterized in that The error of the predicted coke particle size is <1.5%.

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