Method for evaluating coke for improving gas and liquid permeability of dead man in blast furnace and use thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ANSTEEL BEIJING RES INST CO LTD
- Filing Date
- 2024-01-19
- Publication Date
- 2026-06-16
Smart Images
Figure CN117907143B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of ironmaking raw materials and ironmaking, specifically to an evaluation method and application method for coke that improves the air and liquid permeability of the dead charge column in a blast furnace. Background Technology
[0002] The deadweight column is a virtually stationary column of coke located in the center of the blast furnace hearth during ironmaking. Specifically, it's a cone-shaped column of coke located in the hearth center, outside the combustion zone, with its lower part submerged in molten slag and iron and its upper tip protruding into the hearth. Because its consumption and renewal rate are extremely slow, it's called a "deadweight column." The gaps between coke particles in this area are filled with coke powder, molten iron, slag, and unreduced ore. The behavior of the deadweight column directly affects the hearth. If its permeability (air and liquid permeability) deteriorates, it hinders the dripping of molten slag and iron, easily adhering to the coke surface, increasing the deadweight column's volume, affecting blast furnace operation, and leading to abnormal furnace conditions such as suspended material and poor slag discharge. Simultaneously, the deadweight column's own "sinking-floating" reciprocating motion determines the flow of molten iron, further affecting the degree of scouring of the hearth sidewalls. Therefore, the presence and condition of the deadweight column play a decisive role in the lifespan of the hearth. The worse the permeability of the dead material column (air and liquid) and the deeper the dead material column is submerged, the greater the velocity of the molten iron circulation. The molten iron circulation easily causes strong erosion of the hearth carbon bricks. Especially in the elephant foot zone at the bottom of the hearth, the erosion of the molten iron circulation is very severe, forming "elephant foot" erosion.
[0003] The properties and working condition of the dead stockpile are crucial, but the quality of the coke plays a decisive role. Low high-temperature performance of coke severely affects its skeletal function in the blast furnace softening and dripping zones, reducing the overall permeability and liquid permeability of the blast furnace. Currently, there is a lack of suitable performance indicators for characterizing the blast furnace permeability and liquid permeability of coke based on the actual blast furnace environment. Therefore, we propose an evaluation method for coke that improves the permeability and liquid permeability of the blast furnace dead stockpile and its application. Summary of the Invention
[0004] This invention provides an evaluation method and application method for coke that improves the air and liquid permeability of the blast furnace deadweight column. Its main purpose is to address phenomena such as elephant-foot-like abnormal erosion in the blast furnace hearth and molten iron circulation, thereby providing new evaluation indicators and application suggestions for blast furnace coke selection. It also provides technical parameters to guide the selection of blast furnace raw materials and production operations, ensuring the liquid permeability and reducing properties of the blast furnace burden, and improving the reasonable indicators and application effects of coke that improve the air and liquid permeability of the blast furnace deadweight column. This invention obtains coke and iron ore used in blast furnace production, simulates the actual blast furnace environment to treat the coke, and determines the method for measuring the air and liquid permeability indicators of the coke by the water absorption rate of the treated coke. After assessing the compatibility of the air and liquid permeability indicators of coke already in the furnace and coke not yet in the furnace, a central coke addition method is adopted to improve the air and liquid permeability of the blast furnace deadweight column.
[0005] To achieve the above objectives, the present invention employs the following technical solution:
[0006] A method for evaluating coke with improved permeability and liquid permeability of the blast furnace deadweight column, comprising the following steps:
[0007] Step 1: Sampling: Obtain samples of coke and iron ore currently in use during blast furnace production.
[0008] Step 2: Process the coke in a simulated blast furnace operating environment.
[0009] Step 3: Coke water absorption rate test:
[0010] 1) Weighing and drying: Take the coke after the reaction and put it into a drying oven to dry for 30 min to 4 h at 100 to 200 °C; remove iron, iron oxides and unreduced iron ore from the surface of the coke, weigh each piece of dried coke and record the mass m1 of each piece of coke.
[0011] 2) High-pressure leaching: Place the coke into the container in sequence, record the corresponding sequence, and add water to submerge all the coke; evacuate the container until the vacuum degree reaches below 10 kPa, and maintain this vacuum degree for 20 to 60 minutes.
[0012] 3) Weigh and calculate: Release the air from the container, take out all the coke soaked in the container in order, weigh them one by one, and record the mass m2 of each coke in this state (make sure there are no obvious water droplets on the surface when weighing).
[0013] The water absorption rate a (air permeability and liquid permeability index of coke) of all cokes is calculated using m1 and m2, and the corresponding average value A is obtained.
[0014]
[0015] Step 4: Adaptation and testing of air permeability and liquid permeability indices for coke not yet fed into the furnace:
[0016] 1) Replace the coke and iron ore currently in use in the blast furnace production operation with the coke and iron ore to be used in the blast furnace, and then repeat steps two and three to measure the average water absorption rate B (the air permeability and liquid permeability index of the coke to be used).
[0017] 2) If B > A, the coke to be replaced is initially determined; if B ≤ A, it is considered that the average water absorption rate B (the air permeability and liquid permeability index of coke) of the coke to be used is not as good as the coke currently in use in blast furnace production and operation; continue to replace and repeat the operations of steps two and three until B > A.
[0018] 3) Mix the coke currently in use during blast furnace production with the coke to be replaced as initially determined in step 4-2) at a mass ratio of 1:(2-4). At the same time, replace the iron ore currently in use during blast furnace production with the iron ore to be used in blast furnace production. Then repeat the operation of step 2.
[0019] 4) Repeat step 3 to measure the water absorption rate C (air permeability and liquid permeability index of coke) of the mixed coke; if C > A, then the coke initially determined in step 4-3) is the coke to be replaced; if C ≤ A, then it is considered that the air permeability and liquid permeability performance index of the coke initially determined to be replaced is not as good as the coke currently used in the blast furnace production operation, and the operation of step 4-1)-4) is repeated until C > A.
[0020] The coke treatment method in step two above, which simulates the blast furnace operating environment, includes:
[0021] 1) Sample pretreatment:
[0022] Unrepresentative coke samples (such as foamy coke and furnace head coke) are removed, and coke samples with a particle size range of 10–25 mm are obtained through crushing, sieving, and shaping.
[0023] Iron ore raw materials are screened to obtain iron ore samples with a particle size of 10-25 mm, and then mixed and reduced.
[0024] Iron ore raw materials include pellets, sinters, natural lumps, and other iron-containing materials.
[0025] 2) Sample weighing and placement:
[0026] The iron ore sample and the coke sample were weighed at a mass ratio of (8-1):(1-2) (the ratio was based on the actual operation of the blast furnace and the amount of coke and ore added). The total mass of the iron ore and coke was between 200 and 1000 g.
[0027] The weighed coke and iron ore samples are placed in a graphite crucible, with the coke at the bottom and the iron ore at the top. The bottom of the graphite crucible is perforated so that the molten iron can drip down and separate from the coke.
[0028] After the iron ore has been placed, a layer of coke is laid on top to ensure that the pressure devices do not come into direct contact with the iron ore when applying pressure from above.
[0029] 3) Simulated blast furnace environment treatment:
[0030] a) Start heating the crucible containing the material and apply a pressure load of 0.01 to 1 MPa, with an optimal load of 0.1 MPa.
[0031] b) Heating to T0 = 180–220 °C under a nitrogen atmosphere at a rate of 5–20 °C / min.
[0032] c) Continue heating to T1 under a nitrogen atmosphere, where T0 < T1 ≤ 500℃, with a heating rate of 10–20℃ / min. Within this range, coke will not react with iron ore and carbon dioxide or water vapor, so a nitrogen atmosphere is used.
[0033] d) In a mixed atmosphere of 40%–60% N2, 10%–30% CO2, 20%–40% CO, and 0–10% H2O, the temperature is increased from T1 to T2 at a rate of 5–20 °C / min, and 1000 °C ≤ T2 ≤ 1200 °C.
[0034] e) Hold the product at temperature T2 for a duration that is proportional to the heating rate in step d).
[0035] f) In a mixed atmosphere of 40%–60% N2, 0–20% CO2, 30%–50% CO, and 0–10% H2O, at a heating rate of 5–20 °C / min, with a temperature range of 1200 °C < T3 ≤ 1350 °C (the volume ratio of CO2 is lower than that in step d), and the volume ratio of CO is higher than that in step d).
[0036] g) Hold the product at temperature T3 for a period of time that is proportional to the heating rate in step f).
[0037] h) In a mixed atmosphere of 40–60% N2, 0–20% CO2, 30–50% CO, and 0–10% H2O, the temperature is increased from T3 to T4 at a rate of 5–20 °C / min, with a temperature range of 1500 °C ≤ T4 ≤ 1600 °C. (The volume ratio of CO2 is lower than that in step f), and the volume ratio of CO is higher than that in step f).
[0038] i) Keep warm at T4 temperature for 30 to 60 minutes.
[0039] j) Under a nitrogen atmosphere, the furnace is cooled to room temperature from T4.
[0040] k) Remove the unreduced iron ore and the reacted coke.
[0041] The flow rate of the nitrogen atmosphere is 2 to 10 L / min.
[0042] The gas flow rate of the mixed atmosphere in steps d), f), and h) above is 2 to 10 L / min.
[0043] The holding time min in step e) above is 6 * the heating rate in step d).
[0044] The holding time min in step g) above is equal to 2 * the heating rate in step f) + 20.
[0045] A method for evaluating coke that improves the permeability and liquid permeability of the dead charge column in a blast furnace, and a method for using the obtained coke, wherein the coke is added to the blast furnace using a center-adding coke technology.
[0046] Compared with existing technologies, the beneficial effects of this invention are:
[0047] To address current phenomena such as elephant-foot-like abnormal erosion in the blast furnace hearth and iron circulation issues, this invention provides new evaluation indicators and usage recommendations for blast furnace coke selection. It offers technical parameters to guide the selection of blast furnace raw materials and production operations, ensuring the permeability and reducing properties of the blast furnace charge. This helps reduce the operational burden on the ironmaking site, lower the coke ratio, reduce carbon dioxide emissions, increase iron production, and ensure stable blast furnace operation.
[0048] The application of this invention can improve the air and liquid permeability of the blast furnace in the dead charge column, reduce the occurrence of phenomena such as molten iron circulation, reduce the degree of carbon brick erosion, facilitate taphole maintenance, and ensure the long-term stable operation of the blast furnace.
[0049] This invention provides guidance for existing coking coal blending, supports the expansion of coking coal resources, reduces blending costs and improves the profitability of coking enterprises, reduces discrepancies between ironmaking and coking processes regarding coke quality, and avoids the pointless pursuit of excessively high CSR and CRI. Attached Figure Description
[0050] Figure 1 This is a flowchart of the present invention. Detailed Implementation
[0051] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are merely illustrative and are not intended to limit the present invention.
[0052] Example 1:
[0053] Step 1, Sampling: Obtain the coke COKE-1 currently used in blast furnace production and operation; obtain the iron ore raw material currently used in blast furnace production and operation.
[0054] Step 2: Process the coke in a simulated blast furnace operating environment.
[0055] 1) Sample pretreatment:
[0056] Unrepresentative coke samples (such as foamy coke and furnace head coke) are removed, and coke samples with a particle size range of 10–25 mm are obtained through crushing, sieving, and shaping.
[0057] Iron ore raw materials used in blast furnaces are screened to obtain iron ore samples with a particle size of 10-25mm, and then mixed and reduced in size.
[0058] Iron ore raw materials include pellets, sinters, natural lumps, and other iron-containing materials.
[0059] 2) Sample weighing and placement:
[0060] The iron ore sample and the coke sample were weighed at a mass ratio of 8:2, and the total mass of the iron ore and coke was 800.4g.
[0061] The weighed coke and iron ore samples are placed in a graphite crucible, with the coke at the bottom and the iron ore at the top. The bottom of the graphite crucible is perforated so that the molten iron can drip down and separate from the coke.
[0062] After the iron ore has been placed, a layer of coke is laid on top to ensure that the pressure devices do not come into direct contact with the iron ore when applying pressure from above.
[0063] 3) Simulated blast furnace environment treatment:
[0064] a) Start heating the crucible containing the material and apply a pressure load of 0.1 MPa.
[0065] b) Heating to 200°C under a nitrogen atmosphere (gas flow rate of 8 L / min) at a heating rate of 5°C / min.
[0066] c) In a nitrogen atmosphere (gas flow rate of 8 L / min), the temperature is increased from 200 °C to 500 °C at a rate of 10 °C / min.
[0067] d) In a mixed atmosphere (48% N2, 20% CO2, 30% CO, 2% H2O) at a volume ratio (gas flow rate of 8 L / min), the temperature is increased from 500 °C to 1100 °C at a heating rate of 10 °C / min.
[0068] e) Keep warm at 1100℃ for 60 minutes.
[0069] f) In a mixed atmosphere (48% N2, 15% CO2, 35% CO, 2% H2O) at a volume ratio (gas flow rate of 8 L / min), the temperature is increased from 1100 °C to 1300 °C at a heating rate of 5 °C / min.
[0070] g) Keep warm at 1300℃ for 30 minutes.
[0071] h) In a mixed atmosphere (48% N2, 10% CO2, 40% CO, 2% H2O) at a volume ratio (gas flow rate of 8 L / min), the temperature is increased from 1300℃ to 1600℃ at a heating rate of 5℃ / min.
[0072] i) Hold at 1600℃ for 60 minutes;
[0073] j) Under a nitrogen atmosphere (gas flow rate of 2 L / min), the furnace is cooled from 1600 °C to room temperature.
[0074] k) Remove the unreduced iron ore and the reacted coke.
[0075] Step 3: Coke water absorption rate (air permeability and liquid permeability index of coke) test:
[0076] 1) Weighing and drying: Take the coke after the reaction and put it into a drying oven at 120℃ for 2 hours.
[0077] Remove obvious iron and unreduced iron ore from the surface of the coke, weigh each dried coke individually, and record the mass m1 of each coke.
[0078] 2) High-pressure leaching: Place the coke into the container in sequence and record the corresponding order. Add water to submerge all the coke. Evacuate the container until the vacuum degree reaches below 10 kPa and maintain this vacuum degree for 60 minutes.
[0079] 3) Weigh and calculate: Release the air from the container, take out all the coke soaked in the container in order, weigh them one by one, and record the mass m2 of each coke in this state (make sure there are no obvious water droplets on the surface when weighing).
[0080] The water absorption rate a (air permeability and liquid permeability index of coke) of all cokes was calculated using m1 and m2, and the corresponding average value A was found to be 6.95.
[0081] Step 4: Adaptation and testing of air permeability and liquid permeability indices for coke not yet fed into the furnace:
[0082] 1) Replace the coke and iron ore currently used in the blast furnace operation with the coke COKE-2 and iron ore to be used in the blast furnace. Then repeat steps two and three. The average water absorption rate B (the air and liquid permeability index of coke) of the coke to be used was measured to be 6.14. <A。
[0083] 2) Replace the remaining COKE-3 coke to be used, and repeat the operations in steps two and three. The water absorption rate B of the new coke was measured to be 14.03, which is greater than A.
[0084] 3) Replace the coke currently used in blast furnace production with a mixture of COKE-1 coke currently used in blast furnace production and COKE-3 coke to be used in blast furnace production at a mass ratio of 3:7. Replace the iron ore currently used in blast furnace production with the iron ore to be used in blast furnace production, and then repeat step two.
[0085] 4) Repeat step 3 and the water absorption rate C (air permeability index of coke) of the mixed coke is measured to be 9.52, where C>A. It is considered that the air permeability index of the coke COKE-3 to the dead column is higher than that of the coke COKE-1 currently used in blast furnace production.
[0086] 5) Implement the central coking process by adding COKE-3 coke into the blast furnace. The comparison of the situation of a certain blast furnace before and after the addition is shown in Table 1.
[0087] Table 1 Comparison of the situation of a certain blast furnace before and after addition.
[0088] nature Before center focusing After center focusing Blast furnace coke ratio 422 399 Blast furnace utilization coefficient 2.02 2.19
[0089] Example 2:
[0090] Step 1, Sampling: Obtain the coke COKE-1 currently used in blast furnace production and operation; obtain the iron ore raw material currently used in blast furnace production and operation.
[0091] Step 2: Process the coke in a simulated blast furnace operating environment.
[0092] 1) Sample pretreatment:
[0093] Unrepresentative coke samples (such as foamy coke and furnace head coke) are removed, and coke samples with a particle size range of 10–25 mm are obtained through crushing, sieving, and shaping.
[0094] Iron ore raw materials used in blast furnaces are screened to obtain iron ore samples with a particle size of 10-25mm, and then mixed and reduced in size.
[0095] Iron ore raw materials include pellets, sinters, natural lumps, and other iron-containing materials.
[0096] 2) Sample weighing and placement:
[0097] The iron ore sample and the coke sample were weighed at a mass ratio of 8:2, and the total mass of the iron ore and coke was 802.5g.
[0098] The weighed coke and iron ore samples are placed in a graphite crucible, with the coke at the bottom and the iron ore at the top. The bottom of the graphite crucible is perforated so that the molten iron can drip down and separate from the coke.
[0099] After the iron ore has been placed, a layer of coke is laid on top to ensure that the pressure devices do not come into direct contact with the iron ore when applying pressure from above.
[0100] 3) Simulated blast furnace environment treatment:
[0101] a) Start heating the crucible containing the materials and apply a pressure load of 0.1 MPa.
[0102] b) Heating to 200°C under a nitrogen atmosphere (gas flow rate of 8 L / min) at a heating rate of 5°C / min.
[0103] c) In a nitrogen atmosphere (gas flow rate of 8 L / min), the temperature is increased from 200 °C to 500 °C at a rate of 10 °C / min.
[0104] d) In a mixed atmosphere (48% N2, 20% CO2, 30% CO, 2% H2O) at a volume ratio (gas flow rate of 8 L / min), the temperature is increased from 500 °C to 1100 °C at a heating rate of 10 °C / min.
[0105] e) Keep warm at 1100℃ for 60 minutes.
[0106] f) In a mixed atmosphere (48% N2, 15% CO2, 35% CO, 2% H2O) at a volume ratio (gas flow rate of 8 L / min), the temperature is increased from 1100 °C to 1300 °C at a heating rate of 5 °C / min.
[0107] g) Keep warm at 1300℃ for 30 minutes.
[0108] h) In a mixed atmosphere (48% N2, 10% CO2, 40% CO, 2% H2O) at a volume ratio (gas flow rate of 8 L / min), the temperature is increased from 1300℃ to 1600℃ at a heating rate of 5℃ / min.
[0109] i) Hold at 1600℃ for 60 minutes;
[0110] j) Under a nitrogen atmosphere (gas flow rate of 2 L / min), the furnace is cooled from 1600 °C to room temperature.
[0111] k) Remove the unreduced iron ore and the reacted coke.
[0112] Step 3: Coke water absorption rate (air permeability and liquid permeability index of coke) test
[0113] 1) Weighing and drying: Take the coke after the reaction and put it into a drying oven at 120℃ for 2 hours.
[0114] Remove obvious iron and unreduced iron ore from the surface of the coke, weigh each dried coke individually, and record the mass m1 of each coke.
[0115] 2) High-pressure leaching: Place the coke into the container in sequence and record the corresponding order. Add water to submerge all the coke. Evacuate the container until the vacuum degree reaches below 10 kPa and maintain this vacuum degree for 60 minutes.
[0116] 3) Weigh and calculate: Release the air from the container, take out all the coke soaked in the container in order, weigh them one by one, and record the mass m2 of each coke in this state (make sure there are no obvious water droplets on the surface when weighing).
[0117] The water absorption rate a (air permeability and liquid permeability index of coke) of all cokes was calculated using m1 and m2, and the corresponding average value A was found to be 2.23.
[0118] Step 4: Adaptation and testing of air permeability and liquid permeability indices for coke not yet fed into the furnace:
[0119] 1) Replace the coke and iron ore currently in use in the blast furnace production operation with the coke COKE-2 and iron ore to be used in the blast furnace. Then repeat steps two and three. The average water absorption rate B (the air permeability and liquid permeability index of coke) of the coke to be used is measured to be 8.52, where B>A. Therefore, it is preliminarily determined that coke COKE-2 is the coke to be replaced.
[0120] 2) Replace the coke currently used in blast furnace production with a mixture of the coke COKE-1 currently used in blast furnace production and the coke COKE-2 to be used in blast furnace production at a mass ratio of 3:7. Replace the iron ore currently used in blast furnace production with the iron ore to be used in blast furnace production, and then repeat step two.
[0121] 3) Repeat step 3 and the water absorption rate C (the air permeability and liquid permeability index of coke) of the mixed coke is measured to be 7.65, where C>A. It is considered that the air permeability and liquid permeability performance index of the coke COKE-2 to be used is higher than that of the coke COKE-1 currently used in blast furnace production.
[0122] 4) Implement the central coking process by adding coke COKE-2 into the blast furnace. The comparison of the situation of a certain blast furnace before and after the addition is shown in Table 2.
[0123] Table 2 Comparison of the situation of a certain blast furnace before and after addition.
[0124] nature Before center focusing After center focusing Blast furnace coke ratio 435 410 Blast furnace utilization coefficient 1.92 2.15
[0125] Example 3:
[0126] Step 1, Sampling: Obtain the coke COKE-1 currently used in blast furnace production and operation; obtain the iron ore raw material currently used in blast furnace production and operation.
[0127] Step 2: Process the coke in a simulated blast furnace operating environment.
[0128] 1) Sample pretreatment:
[0129] Unrepresentative coke samples (such as foamy coke and furnace head coke) are removed, and coke samples with a particle size range of 10–25 mm are obtained through crushing, sieving, and shaping.
[0130] Iron ore raw materials used in blast furnaces are screened to obtain iron ore samples with a particle size of 10-25mm, and then mixed and reduced in size.
[0131] Iron ore raw materials include pellets, sinters, natural lumps, and other iron-containing materials.
[0132] 2) Sample weighing and placement:
[0133] The iron ore sample and the coke sample were weighed at a mass ratio of 8:2, and the total mass of the iron ore and coke was 812.3g.
[0134] The weighed coke and iron ore samples are placed in a graphite crucible, with the coke at the bottom and the iron ore at the top. The bottom of the graphite crucible is perforated so that the molten iron can drip down and separate from the coke.
[0135] After the iron ore has been placed, a layer of coke is laid on top to ensure that the pressure devices do not come into direct contact with the iron ore when applying pressure from above.
[0136] 3) Simulated blast furnace environment treatment:
[0137] a) Start heating the crucible containing the material and apply a pressure load of 0.1 MPa.
[0138] b) Heating to 200°C under a nitrogen atmosphere (gas flow rate of 8 L / min) at a heating rate of 5°C / min.
[0139] c) In a nitrogen atmosphere (gas flow rate of 8 L / min), the temperature is increased from 200 °C to 500 °C at a rate of 10 °C / min.
[0140] d) In a mixed atmosphere (48% N2, 20% CO2, 30% CO, 2% H2O) at a volume ratio (gas flow rate of 8 L / min), the temperature is increased from 500 °C to 1100 °C at a heating rate of 10 °C / min.
[0141] e) Keep warm at 1100℃ for 60 minutes.
[0142] f) In a mixed atmosphere (48% N2, 15% CO2, 35% CO, 2% H2O) at a volume ratio (gas flow rate of 8 L / min), the temperature is increased from 1100 °C to 1300 °C at a heating rate of 5 °C / min.
[0143] g) Keep warm at 1300℃ for 30 minutes.
[0144] h) In a mixed atmosphere (48% N2, 10% CO2, 40% CO, 2% H2O) at a volume ratio (gas flow rate of 8 L / min), the temperature is increased from 1300℃ to 1600℃ at a heating rate of 5℃ / min.
[0145] i) Hold at 1600℃ for 60 minutes;
[0146] j) Under a nitrogen atmosphere (gas flow rate of 2 L / min), the furnace is cooled from 1600 °C to room temperature.
[0147] k) Remove the unreduced iron ore and the reacted coke.
[0148] Step 3: Coke water absorption rate (air permeability and liquid permeability index of coke) test:
[0149] 1) Weighing and drying: Take the coke after the reaction and put it into a drying oven at 120℃ for 2 hours.
[0150] Remove obvious iron and unreduced iron ore from the surface of the coke, weigh each dried coke individually, and record the mass m1 of each coke.
[0151] 2) High-pressure leaching: Place the coke into the container in sequence and record the corresponding order. Add water to submerge all the coke. Evacuate the container until the vacuum degree reaches below 10 kPa and maintain this vacuum degree for 60 minutes.
[0152] 3) Weigh and calculate: Release the air from the container, take out all the coke soaked in the container in order, weigh them one by one, and record the mass m2 of each coke in this state (make sure there are no obvious water droplets on the surface when weighing).
[0153] The water absorption rate a (air permeability and liquid permeability index of coke) of all cokes was calculated using m1 and m2, and the corresponding average value A was found to be 5.89.
[0154] Step 4: Adaptation and testing of air permeability and liquid permeability indices for coke not yet fed into the furnace:
[0155] 1) Replace the coke and iron ore currently in use during the blast furnace production operation with the coke COKE-2 and iron ore that the blast furnace is prepared to use, and then repeat the operations in steps two and three. The measured average water absorption rate B (the air and liquid permeability index of the coke) of the coke prepared for use is 9.16. Since B > A, it is preliminarily determined that coke COKE-2 is the coke to be replaced.
[0156] 2) Replace the coke currently in use during the blast furnace production operation, mix the coke COKE-1 currently in use during the blast furnace production operation and the coke COKE-2 prepared for use in a mass ratio of 3:7, and replace the iron ore currently in use during the blast furnace production operation with the iron ore prepared for blast furnace production. Then repeat the operation in step two.
[0157] 3) Repeat step three, and the measured water absorption rate C (the air and liquid permeability index of the coke) of the mixed coke is 5.50. Since C < A, it is considered that the coke COKE-2 prepared for use does not have a higher air and liquid permeability performance index for the dead stock column than the coke COKE-1 currently in use during the blast furnace production operation.
[0158] 4) Replace the remaining coke COKE-3 prepared for use, and repeat the operations in steps two and three. The measured water absorption rate B of the new coke is 12.67. Since B > A, it is preliminarily determined that coke COKE-3 is the coke to be replaced.
[0159] 5) Replace the coke currently in use during the blast furnace production operation, mix the coke COKE-1 currently in use during the blast furnace production operation and the coke COKE-3 prepared for use in a mass ratio of 3:7, and replace the iron ore currently in use during the blast furnace production operation with the iron ore prepared for blast furnace production. Then repeat the operation in step two.
[0160] 6) Repeat step three, and the measured water absorption rate C (the air and liquid permeability index of the coke) of the mixed coke is 10.14. Since C > A, it is considered that the coke COKE-3 prepared for use has a higher air and liquid permeability performance index for the dead stock column than the coke COKE-1 currently in use during the blast furnace production operation.
[0161] 7) Implement center coke charging and add coke COKE-3 into the blast furnace. The comparison of the situation of a certain blast furnace before and after the addition is shown in Table 3.
[0162] Table 3 Comparison of the situation of a certain blast furnace before and after the addition
[0163] nature Before center focusing After center focusing Blast furnace coke ratio 427 398 Blast furnace utilization coefficient 1.99 2.32 .
Claims
1. A method for evaluating coke with improved air and liquid permeability of the blast furnace deadweight column, characterized in that, The methods and steps include the following: Step 1: Sampling: Obtain samples of coke and iron ore currently in use during blast furnace production and operation; Step 2: Process coke in a simulated blast furnace operating environment; Step 3: Coke water absorption rate test: 1) Weighing and drying: Take the coke after the reaction and put it into a drying oven to dry; weigh each piece of dried coke and record the mass m1 of each piece of coke. 2) High-pressure leaching: Place the coke in a container and add water to submerge all the coke; evacuate the container until the vacuum level reaches below 10 kPa, and maintain this vacuum level for 20 to 60 minutes; 3) Weigh and calculate: Take out all the coke soaked in the container and weigh them one by one, and record the mass m2 of each coke in this state; The water absorption rate 'a' of all cokes is calculated using m1 and m2, and the corresponding average value 'A' is obtained. Step 4: Adaptation and testing of air permeability and liquid permeability indices for coke not yet fed into the furnace: 1) Replace the coke and iron ore currently in use during blast furnace production with the coke and iron ore that the blast furnace is preparing to use. Then repeat steps two and three to measure the average water absorption rate B of the coke to be used. 2) If B > A, the coke to be replaced is initially determined; if B ≤ A, the coke is replaced and steps two and three are repeated until B > A. 3) Mix the coke currently in operation of the blast furnace with the coke to be replaced as initially determined in step 4-2) at a mass ratio of 1:(2-4). At the same time, replace the iron ore currently in operation of the blast furnace with the iron ore to be used in the blast furnace production. Then repeat the operation of step 2. 4) Repeat step 3 to measure the water absorption rate C of the mixed coke; if C > A, then determine the coke initially determined in step 4-3) as the coke to be replaced; if C ≤ A, replace the coke and continue repeating the operation of step 4-1)-4) until C > A.
2. The evaluation method for improving the air and liquid permeability of the blast furnace deadweight column according to claim 1, characterized in that, The drying temperature in step 3-1) above is 100-200℃, and the drying time is 30 min-4 h.
3. The method for evaluating coke with improved air and liquid permeability of the blast furnace deadweight column according to claim 1, characterized in that, The coke treatment method in step two above, which simulates the blast furnace operating environment, includes: 1) Sample pretreatment: Coke and iron ore samples were obtained by crushing, screening and shaping. 2) Sample weighing and placement: The iron ore sample and the coke sample were weighed at a mass ratio of (8-1):(1-2); The weighed coke and iron ore samples were placed in a graphite crucible, with the coke at the bottom and the iron ore at the top. The bottom of the graphite crucible was perforated so that the molten iron could drip down and separate from the coke. After placing the iron ore, cover it with another layer of coke. 3) Simulated blast furnace environment treatment: a) Start heating the crucible containing the material and apply a pressure load of 0.01 to 1 MPa; b) Heat to T0 = 180-220℃ under a nitrogen atmosphere at a heating rate of 5-20℃ / min; c) Continue heating to T1 under a nitrogen atmosphere, where T0 < T1 ≤ 500℃, and the heating rate is 10–20℃ / min; d) In a mixed atmosphere of 40%–60% N2, 10%–30% CO2, 20%–40% CO, and 0–10% H2O, the temperature is increased from T1 to T2 at a rate of 5–20 °C / min, and 1000 °C ≤ T2 ≤ 1200 °C. e) Hold the temperature at T2 for a period of time that is proportional to the heating rate in step d); f) In a mixed atmosphere of 40%–60% N2, 0–20% CO2, 30%–50% CO, and 0–10% H2O, the temperature is increased from T2 to T3 at a rate of 5–20 °C / min, and 1200 °C < T3 ≤ 1350 °C. g) Hold at temperature T3 for a period of time that is directly proportional to the heating rate in step f); h) In a mixed atmosphere of 40-60% N2, 0-20% CO2, 30-50% CO, and 0-10% H2O, the temperature is increased from T3 to T4 at a rate of 5-20℃ / min, with a temperature of 1500℃≤T4≤1600℃. i) Keep warm at temperature T4 for 30 to 60 minutes; j) Under a nitrogen atmosphere, the furnace is cooled to room temperature from T4.
4. The evaluation method for improving the air and liquid permeability of the blast furnace deadweight column according to claim 3, characterized in that, The particle size of the coke and iron ore samples is 10–25 mm.
5. The method for evaluating coke with improved air and liquid permeability of the blast furnace deadweight column according to claim 3, characterized in that, The total mass of the iron ore sample and the coke sample is between 200 and 1000 g.
6. The method for evaluating coke with improved air and liquid permeability of the blast furnace deadweight column according to claim 3, characterized in that, The flow rate of the nitrogen atmosphere is 2 to 10 L / min.
7. The method for evaluating coke with improved air and liquid permeability of the blast furnace deadweight column according to claim 3, characterized in that, The gas flow rate of the mixed atmosphere in steps d), f), and h) above is 2 to 10 L / min.
8. The method for evaluating coke with improved air and liquid permeability of the blast furnace deadweight column according to claim 3, characterized in that, The holding time min in step e) above is 6 * the heating rate in step d).
9. The method for evaluating coke with improved air and liquid permeability of the blast furnace deadweight column according to claim 3, characterized in that, The holding time min in step g) above is equal to 2 * the heating rate in step f) + 20.
10. The method of using coke obtained by the evaluation method for improving the air and liquid permeability of the blast furnace deadweight column as described in claim 1, characterized in that... The coke is added to the blast furnace using the center coking technology.