A method for reducing cost based on coking blending coal

Abstract

The application discloses a method for reducing cost based on coking coal blending, and the method comprises the following steps: collecting a tuyere coke sample from a blast furnace tuyere, removing a slag-iron mixture, screening the remaining coke, and measuring an average particle size MS0; after the blast furnace uses the adjusted coal blending structure to produce coke for several days, a tuyere coke sample of the blast furnace is collected again, and an average particle size MS1 of the tuyere coke is measured; if MS1-MS0<2mm, that is, the average particle size of the tuyere coke of the blast furnace is similar before and after the adjustment of the coal blending structure, the adjustment is ended; if MS1-MS0>=2mm, the coal blending structure is continuously adjusted until MS1-MS0<2mm. The application optimizes the coal blending structure on the basis of sampling the average particle size of the tuyere coke of the blast furnace, maintains the average particle size of the tuyere coke of the blast furnace stable while reducing the cost of the coal blending, and further ensures that the blast furnace smelting is stably carried out.

Description

Technical Field

[0001] This invention relates to a method for reducing costs based on coking coal blending, and belongs to the technical field of coking coal blending. Background Technology

[0002] Coke is a crucial raw material for blast furnace ironmaking, and its quality significantly impacts technical and economic indicators and the stable operation of the blast furnace. High cold and hot strength, along with a large average particle size, results in good permeability of the blast furnace's internal burden, a rational airflow distribution, and active hearth operation. However, improving coke quality requires the support of high-quality, high-priced coking coal resources, which inevitably increases coking costs. Therefore, how to rationally improve coke quality and reduce coking costs has become a hot topic of discussion in both the coking coal blending and blast furnace ironmaking sectors.

[0003] Existing technologies for reducing coking costs primarily focus on the changing trends of coke's cold and hot strength, average particle size, and other indicators, without considering the changes in the actual degree of coke deterioration within the blast furnace when the coal blending structure undergoes significant changes. Patent application CN110628446A describes a coking method to improve coke particle size. It classifies coking coal into high-rank and low-rank coking coal based on whether the coal rock reflectance R is greater than 1.3%, controls the proportion of each during blending, and pre-crushes coking coal with a Gibbs freeness MF ≤ 100 ddpm to achieve both increased average coke particle size and controlled coking costs. Patent application CN113845932A describes a method for blending lean coking coal from Shanxi province. By adding lean coking coal with a coking CSR of 63.6% (a single type of coal), it increases economic benefits while maintaining high levels of coke's cold and hot strength. While optimizing the coal blending structure to reduce coal blending costs, the two patent applications focused on changes in coke quality, but did not further analyze the deterioration of coke produced by different coal blending structures inside the blast furnace.

[0004] Coke quality has a significant impact on blast furnace ironmaking. Maintaining good coke quality is necessary to ensure good technical and economic indicators for the blast furnace. However, improving coke quality requires the support of high-quality, high-priced coking coal resources. Therefore, coke quality should be scientifically controlled, and should not be higher or lower than a reasonable range. Existing coal blending methods to reduce coking costs and appropriately improve coke quality mainly improve coke quality by adding coking coal pretreatment processes and introducing new coal types. However, these methods do not consider the deterioration of coke in the blast furnace after adjusting the coal blending structure. In this case, if the adjusted coke has excessive quality, the corresponding cost reduction will be significantly reduced, meaning there is still room for cost reduction. If the adjusted coke quality is insufficient, blast furnace production will be affected. Finding a scientific balance point for coke quality has practical economic significance. Summary of the Invention

[0005] To address the aforementioned problems, this invention discloses a method for reducing costs based on coking coal blending. By using the deterioration of coke within the blast furnace as feedback, and scientifically and quantitatively adjusting the coal blending structure, it is possible to maximize cost reduction while controlling coke quality within a reasonable range, avoiding both over- and under-quality. The specific technical solution is as follows:

[0006] A method for reducing costs based on coking coal blending includes the following steps:

[0007] Step 1: Before optimization and adjustment, remove the tuyere coke sample from the blast furnace tuyere, put the tuyere coke sample into a sealed container, and purge it with nitrogen for protection.

[0008] Step 2: After the tuyeres coke sample has cooled to room temperature, use a magnet to remove the slag-iron mixture, sieve the remaining coke, and measure the average particle size MS0.

[0009] Step 3: The coking coal portion of the coke fed into the furnace corresponding to the tuyere coke in Step 2 (i.e., the coke obtained by the coal blending structure through which the coke is refined is added to the blast furnace and reacted before entering the blast furnace tuyere area to become tuyere coke) is classified according to the coking CSR value of the single-type coal small coke oven. CSR≥55% is classified as JM1, and CSR<55% is classified as JM2.

[0010] Step 4: Adjust the coal blending structure: reduce the proportion of JM2 by a%, with a% ranging from 4% to 6%, increase the proportion of JM1 by (a / 2)%, and increase the proportion of lean coal by (a / 2)%. Since the price difference between lean coal and JM2 is higher than the price difference between JM1 and JM2, this process will reduce the coal blending cost.

[0011] Step 5: After the blast furnace has been producing coke for several days using the adjusted coal blending structure, the coke samples from the blast furnace outlet are collected again, and the average particle size MS1 of the coke from the outlet is measured.

[0012] Step 6: If MS1-MS0 < 2mm, that is, the average particle size of coke at the blast furnace tuyeres is similar before and after the coal blending structure adjustment, then the adjustment is complete. If MS1-MS0 ≥ 2mm, then continue to adjust the coal blending structure according to the methods in Steps 4 and 5 until MS1-MS0 < 2mm.

[0013] Furthermore, in step 1, the tuyere sleeve is removed during the blast furnace shutdown, and the tuyere coke sample is removed from the tuyere.

[0014] Furthermore, in step 1, 10-20 kg of kerosene sample is used.

[0015] Furthermore, in step 1, a stainless steel sealed container is selected.

[0016] Furthermore, in step 2, the single coal and the components of the coal blending structure are obtained by mixing 8-12 types (preferably around 10 types) of single coal to obtain blended coal.

[0017] Furthermore, in step 5, the cycle for recollecting the coke sample from the air outlet is 7 to 10 days.

[0018] Furthermore, the specific process for measuring the average particle size MS0 in step 6 is as follows: the remaining coke is sequentially sieved using 40mm, 30mm, 20mm, and 10mm sieves. The weight of the material on each sieve is: m >40 m 30-40 m 20-30 m 10-20 m <10 Calculate the average particle size: MS0 = (70 × m) >40 +35×m 30-40 +25×m 20-30 +15×m 10-20 +5×m <10 ) / (m >40 +m 30-40 +m 20-30 +m 10-20 +m <10 ).

[0019] Furthermore, in step 6, when 2mm≤MS1-MS0<3mm, the range of a is 4-5%, and when 3mm≤MS1-MS0, the range of a is 5-6%.

[0020] The working principle of this invention is:

[0021] In the process of reducing costs through coking coal blending, this invention focuses on tracking the changes in the deterioration of coke produced inside the blast furnace after changes in the coal blending structure. Although some existing patents can reduce coking costs by adjusting the coal blending structure while meeting coke quality requirements, blast furnace smelting is extremely complex, and the actual deterioration of coke inside the furnace cannot be fully reflected by conventional coke analysis indicators, sometimes with significant discrepancies. In such cases, if coal blending is based on the actual degree of coke deterioration inside the blast furnace to reduce costs, the cost reduction effect will be more significant and less likely to cause abnormal fluctuations in the blast furnace.

[0022] Both the basic and optimized coal blending structures must meet the following requirements: coking coal proportion of 35-55%, fat coal proportion of 15-25%, caking index G of blended coal between 80±2, and maximum cuticle thickness Y of blended coal ≥14.5mm.

[0023] The small coke oven coking process involves in-depth analysis of the indicators of a single type of coal before blending, providing a reference for determining the blending ratio. The single type of coal is placed in an experimental small coke oven to produce coke. Samples are prepared according to requirements and heated to 1100℃ to react with CO2. The proportion of large-particle coke reflects its ability to resist CO2 erosion.

[0024] The beneficial effects of this invention are:

[0025] This invention promotes cost reduction by gradually adjusting the coke deterioration level in the blast furnace based on the dynamic changes before and after the coal blending structure adjustment. It can maximize the reduction of coal blending costs while ensuring that the coke quality meets the production needs of the blast furnace, and avoid the occurrence of quality over- or under-quality. Detailed Implementation

[0026] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0027] The following is a specific embodiment of the present invention in a particular application:

[0028] 1) Before optimization and adjustment, a certain 2000m 3 When the blast furnace is shut down, the tuyere sleeve is removed, 15kg of tuyere coke sample is taken out from the tuyere, put into a stainless steel can, and then filled with nitrogen for protection.

[0029] 2) After the sample cooled to room temperature, the slag-iron mixture was removed with a magnet, and the remaining coke was sieved. The average particle size MS0 was measured to be 20 mm.

[0030] 3) The coking coal portion of the coal blending structure is divided according to the coking coal coking CSR value of a single type of coal in a small coke oven. CSR ≥ 55% is classified as JM1, and CSR < 55% is classified as JM2. In the corresponding coal blending structure for coke used in this blast furnace, JM1 = 25% and JM2 = 21%.

[0031] 4) Adjust the coal blending structure: reduce the proportion of JM2 by 6%, increase the proportion of JM1 by 3%, increase the proportion of lean coal by 3%, the price difference between lean coal and JM2 is 600 yuan / t, and the price difference between JM1 and JM2 is 300 yuan / t, so this process will reduce the coal blending cost.

[0032] 5) After using coke produced by adjusting the coal blending structure in the blast furnace for 10 days, the average particle size of the coke at the tuyeres was remeasured, MS1 = 21 mm;

[0033] 6) MS1-MS0=1mm<2mm, the average particle size of coke at the blast furnace tuyeres is similar before and after the coal blending structure adjustment, and the adjustment is completed.

[0034] The method of this invention is based on the applicant's research on the deterioration and fluctuation of coke quality in the blast furnace corresponding to different coal blending structures. The findings show that appropriately increasing the proportion of high-quality coking coal, reducing the total proportion of coking coal, and increasing the proportion of lean coal can improve the average particle size of coke while maintaining the basic stability of the cold and hot strength of coke. Using this method, the average particle size of coke entering the blast furnace and the average particle size of coke at the tuyeres can be improved to a certain extent, thereby improving the permeability of the burden and creating space for reducing coal blending costs.

[0035] The technical means disclosed in this invention are not limited to those disclosed above, but also include technical solutions composed of any combination of the above technical features.

[0036] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for reducing costs based on coking coal blending, characterized in that, Includes the following steps: Step 1: Before optimization and adjustment, remove the tuyere coke sample from the blast furnace tuyere, put the tuyere coke sample into a sealed container, and purge it with nitrogen for protection. Step 2: After the tuyeres coke sample has cooled to room temperature, use a magnet to remove the slag-iron mixture, sieve the remaining coke, and measure the average particle size MS0. Step 3: Divide the coking coal portion of the coke fed into the furnace corresponding to the tuyeres coke in Step 2 according to the coking CSR value of the small coke oven of a single type of coal. If CSR≥55%, it is divided into JM1, and if CSR<55%, it is divided into JM2. Step 4: Adjust the coal blending structure: reduce the proportion of JM2 by a%, with a% ranging from 4% to 6%, increase the proportion of JM1 by (a / 2)%, and increase the proportion of lean coal by (a / 2)%. Since the price difference between lean coal and JM2 is higher than the price difference between JM1 and JM2, this process will reduce the coal blending cost. Step 5: After the blast furnace has been producing coke for several days using the adjusted coal blending structure, the coke samples from the blast furnace outlet are collected again, and the average particle size MS1 of the coke from the outlet is measured. Step 6: If MS1-MS0 < 2mm, that is, the average particle size of coke at the blast furnace tuyeres is similar before and after the coal blending structure adjustment, then the adjustment is complete. If MS1-MS0 ≥ 2mm, then continue to adjust the coal blending structure according to the methods in Steps 4 and 5 until MS1-MS0 < 2mm.

2. The method for reducing costs based on coking coal blending according to claim 1, characterized in that, In step 1, the tuyere sleeve is removed during the blast furnace shutdown, and the tuyere coke sample is removed from the tuyere.

3. The method for reducing costs based on coking coal blending according to claim 1, characterized in that, In step 1, 10-20 kg of kerosene sample is used.

4. The method for reducing costs based on coking coal blending according to claim 1, characterized in that, In step 1, a stainless steel sealing container is selected.

5. The method for reducing costs based on coking coal blending according to claim 1, characterized in that, In step 3, the coal blending structure is obtained by mixing 8-12 kinds of single coal to obtain blended coal; The CSR value of coke produced in small coke ovens is obtained by conducting in-depth analysis of the indicators of a single type of coal before blending, providing a reference for determining the blending ratio. A single type of coal is placed in an experimental small coke oven to produce coke. Samples are prepared as required and heated to 1100℃ to react with CO2. The proportion of large-particle coke reflects its ability to resist CO2 erosion.

6. The method for reducing costs based on coking coal blending according to claim 1, characterized in that, In step 5, the period for re-collecting the coke sample from the air outlet is 7 to 10 days.

7. The method for reducing costs based on coking coal blending according to claim 1, characterized in that, The specific process for measuring the average particle size MS0 in step 2 is as follows: The remaining coke is sequentially sieved using 40mm, 30mm, 20mm, and 10mm sieves. The weight of the sieved material for each sieve size is: m >40 m 30-40 m 20-30 m 10-20 m <10 Calculate the average particle size: MS0 = (70 × m) >40 +35×m 30-40 +25×m 20-30 +15×m 10-20 +5×m <10 ) / (m >40 +m 30-40 +m 20-30 +m 10-20 +m <10 ).

8. The method for reducing costs based on coking coal blending according to claim 1, characterized in that, In step 6, when 2mm≤MS1-MS0<3mm, the range of a% is 4%-5%, and when 3mm≤MS1-MS0, the range of a% is 5%-6%.