Method for adding damping-down material before long-term damping-down of blast furnace

Abstract

The invention relates to a method for adding damping-down materials before long-term damping-down of a blast furnace. The damping-down materials comprise light-load materials and empty coke. The load of the light-load material can be reduced progressively according to the smooth running condition of the blast furnace before damping down, or the load of the furnace material before damping down is maintained. The adding amount of each batch of empty coke is 1.0-1.5 times of that of the coke batch before damping down. The loaded empty coke is completely composed of dry quenching coke with reasonable indexes. When empty coke is added, the flux dosage is not additionally increased any more. And the first batch of empty coke is loaded at the middle position of the furnace bosh. The second batch of empty coke is loaded in the middle of the furnace bosh, the third batch of empty coke is loaded in the lower part of the furnace body, and the fourth batch of empty coke is loaded in the middle of the furnace body. According to the invention, the addition of empty coke is reduced, the recovery of hearth heat is promoted, and the fuel ratio of the blast furnace is reduced.

Description

Technical Field

[0001] The present application relates to the production technology of blast furnaces in iron and steel metallurgy, and in particular to a method for charging blast furnace materials for long-term blast-out (24-30 hours) periods, belonging to the field of blast furnace ironmaking technology. Background Art

[0002] Blast furnace blast-off charges primarily refer to normal coke and empty coke. Normal coke refers to a batch of coke and ore added to the blast furnace according to a specific distribution matrix; empty coke refers to coke added directly to the blast furnace according to a preset distribution matrix without the addition of ore. The ratio of the mass of ore to the mass of coke in normal coke is defined as the smelting load. Generally, the load of normal coke in the blast-off charge is lower than the load before the blast-off, and is referred to as light-load charge. The method of loading the blast-off charge is a key factor in enabling the blast furnace to be quickly restored after a long blast-off (24-30 hours). The amount of coke added to a traditional blast-off charge depends on the length of the blast-off period. Long-term blast-offs require consideration not only of the appropriate amount of empty coke and light-load charge, but also of their proper placement within the furnace. Generally, during long-term blast-offs, the frontmost empty coke or light-load charge is best placed at the lower furnace waist or upper furnace belly, as this area is generally considered the soft melting zone of the blast furnace and presents the greatest resistance to airflow after restoration.

[0003] Chinese patent publication number CN105950808A discloses a method for adjusting the charge structure of a blast furnace before shutting down during ironmaking. The first section of empty coke is located in the blast furnace hearth, the second section is located above the furnace belly, and the third section is located below the blast furnace shaft. This process is more suitable for shutting down blast furnaces with smaller capacity and requires higher coke consumption. This method and principle for adjusting the charge structure of a light-duty charge are not yet mentioned in the patent.

[0004] Chinese patent publication number CN114807466A discloses a method for adjusting and adding blast furnace charge before a long-term blast furnace shutdown. This method requires adding a mixed layer of scrap steel and coke to the lower furnace section, which places stringent requirements on the blast furnace charge and increases the difficulty of implementing the patent. Furthermore, the patent is specifically designed for situations where the blast furnace shutdown lasts longer than 30 hours.

[0005] In summary, existing methods for adding hollow coke and light-loaded materials to the blast furnace lack specific implementation plans and procedures. Furthermore, the addition of blast furnace materials largely relies on operator experience, and excessive coke is often added for safety reasons. This results in low gas utilization after re-airing and even disrupted airflow, hindering rapid recovery of blast furnace conditions and optimizing performance. Therefore, a new solution is urgently needed to address these technical issues. Summary of the Invention

[0006] The present invention is aimed at the problems existing in the prior art and provides a method for adding blast material before a long-term blast shutdown to solve the technical problem of unsmooth re-blowing caused by unreasonable addition of blast material before a long-term blast shutdown.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows: a method for adding blast material before long-term blast shutdown of a blast furnace, the method comprising the following steps:

[0008] Blast-out charges include light-loaded charge and empty coke. The light-loaded charge can be reduced as appropriate based on the furnace's operating conditions before the blast-out, or maintained at the same charge load as before. Each batch of empty coke should be 1.0-1.5 times the amount of coke before the blast-out. All empty coke charged should consist entirely of dry-quenched coke with reasonable specifications. No additional flux is added when empty coke is added. The first batch of empty coke is charged into the middle of the furnace belly, the second batch into the middle of the furnace waist, the third batch into the lower part of the furnace body, and the fourth batch into the middle of the furnace body.

[0009] After the blast furnace is charged, the following conditions must be met: slag binary basicity R2 ≤ 1.10; [Si] in hot metal: 0.30%-0.50%; [S] in hot metal: 0.020%-0.045%; [Si] in the hot metal before the blast furnace is charged: 0.50%-0.70%; physical heat ≥ 1510°C; and furnace top temperature ≥ 120°C.

[0010] Among them, in the bosh area, light-load materials are added first according to the volume of the bosh area. The light-load materials fill half of the bosh volume and then a batch of empty coke is added. Then light-load materials are added and finally a batch of empty coke is added to fill the bosh area.

[0011] Among them, in the furnace waist area, half of the volume of the furnace waist is loaded with light-load materials first, then a batch of empty coke is loaded, and finally the furnace waist is filled with light-load materials.

[0012] The furnace body is divided into three equal sections by height, starting from the upper edge of the furnace waist and ending at the lower edge of the furnace throat. These sections are referred to as the lower furnace body, the middle furnace body, and the upper furnace body, depending on their elevation. First, half the volume of the lower furnace body is loaded with light-loaded charge, followed by a batch of empty coke. Light-loaded charge is then added, and the lower furnace body is filled to capacity.

[0013] Among them, half of the volume of light-load material is first loaded into the furnace body, followed by adding a batch of empty coke, and then continuing to load light-load material until the furnace body is full. Only light-load material is loaded into the furnace body until the throat material line. The preset position of the throat material line is the same as that of normal smelting before the blast furnace is shut down.

[0014] Compared with the prior art, the present invention has the following advantages: 1. In the present invention, if there is no equipment damage such as water leakage before the blast-out charge is loaded, the blast-out charge load is the same as the charge load before the blast-out, and no additional coke is added. This can achieve the rational use of coke and promote the rapid re-airing of the blast furnace; 2. The present invention does not add additional empty coke below the furnace bosh. Since the area below the furnace bosh is originally below the soft melting zone, there is a large amount of coke. Adding empty coke will cause the heat generated in the lower area of the blast furnace to be carried away by the gas, and due to the lack of ore, the output of molten slag iron decreases, resulting in the failure of heat to be transferred to the furnace hearth through the dripping of molten slag iron. Therefore, the present invention not only reduces the addition of empty coke, but also promotes the recovery of heat in the furnace hearth, thereby reducing the fuel ratio of the blast furnace. 3. In the present invention, when the furnace condition is in a smooth flow before the wind-out, the wind-out material load is the same as the furnace charge load before the wind-out. If the furnace condition is not in a smooth flow, the ore-coke ratio can be lowered in advance to make the furnace condition smooth. The load of the light-load material does not change during the wind-out process, which reduces the air flow turbulence caused by the load change of the light-load material during the wind-out process, reduces the fluctuation of the blast furnace gas utilization rate, and reduces the heat loss of the blast furnace. 4. The present invention does not add extra empty coke below the furnace bosh, which avoids the accumulation of a large amount of coke in the furnace, reduces the circulation resistance of the molten iron in the furnace, increases the kinetic energy of the molten iron and increases the activity of the furnace, is conducive to the uniform distribution of heat in the furnace, and can also prevent the iron mouth from being too large and the iron mouth from being too deep, which is conducive to the rapid opening of the first furnace iron mouth after the re-airing, and improves the blast furnace's ability to receive air volume. Promote the rapid re-airing of the blast furnace. DETAILED DESCRIPTION

[0015] In order to deepen the understanding of the present invention, the present invention is described in detail below with reference to the embodiments.

[0016] Example 1: A method for adding blast furnace blast-out material before a long-term blast-out, the method comprising the following steps: the blast-out material comprises light-load material and empty coke, the light-load material load can be reduced as appropriate according to the smooth operation of the blast furnace before the blast-out, or the charge load before the blast-out can be maintained. The amount of each batch of empty coke added is between 1.0-1.5 times the amount of coke batch before the blast-out, and the empty coke loaded is entirely composed of dry-quenched coke with reasonable indicators, and no additional flux amount is added when adding the empty coke. The first batch of empty coke is loaded into the middle of the furnace belly, the second batch of empty coke is loaded into the middle of the furnace waist, the third batch of empty coke is loaded into the lower part of the furnace body, and the fourth batch of empty coke is loaded into the middle of the furnace body.

[0017] After the blast furnace is charged, the following conditions must be met: slag binary basicity R2 ≤ 1.10; [Si] in hot metal: 0.30%-0.50%; [S] in hot metal: 0.020%-0.045%; [Si] in the hot metal before the blast furnace is charged: 0.50%-0.70%; physical heat ≥ 1510°C; and furnace top temperature ≥ 120°C.

[0018] Among them, in the bosh area, light-load materials are added first according to the volume of the bosh area. The light-load materials fill half of the bosh volume and then a batch of empty coke is added. Then light-load materials are added and finally a batch of empty coke is added to fill the bosh area.

[0019] Among them, in the furnace waist area, half of the volume of the furnace waist is loaded with light-load materials first, then a batch of empty coke is loaded, and finally the furnace waist is filled with light-load materials.

[0020] The furnace body is divided into three equal sections by height, starting from the upper edge of the furnace waist and ending at the lower edge of the furnace throat. These sections are referred to as the lower furnace body, the middle furnace body, and the upper furnace body, depending on their elevation. First, half the volume of the lower furnace body is loaded with light-loaded charge, followed by a batch of empty coke. Light-loaded charge is then added, and the lower furnace body is filled to capacity.

[0021] Among them, half of the volume of light-load material is first loaded into the furnace body, followed by adding a batch of empty coke, and then continuing to load light-load material until the furnace body is full. Only light-load material is loaded into the furnace body until the throat material line. The preset position of the throat material line is the same as that of normal smelting before the blast furnace is shut down.

[0022] Example 2: A company has a 4070m 3 For blast furnaces, the outage time is 24 hours. The normal batch weight of ore is 106t / batch, and the batch weight of coke is 23.55t / batch.

[0023] A method for charging blast furnace blast material for long-term blast shutdown (24-30 hours) comprises the following steps:

[0024] 1) Smelting cycle refers to the time it takes for the charge to travel from the throat line to the center line of the tuyere. Taking the wind-down start time as the boundary, light load charge is added one smelting cycle in advance. Specifically, 4000m 3 Light-load charging should begin eight hours in advance. Light-load charging maintains a normal charge weight of 106 tons of ore per batch and 23.55 tons of coke per batch, maintaining the same load as before the shutdown. The load can be reduced as appropriate to increase charge permeability, depending on the furnace's operating conditions.

[0025] 2) First, load half of the furnace's bosh volume with lightly loaded material, followed by a batch of empty coke. The mass of the empty coke should be the same as that of a normal coke batch, and the empty coke distribution matrix should be the same as that of a normal coke batch. Then, continue loading the lightly loaded material, and finally, load a batch of empty coke at the top edge of the furnace. The mass of the empty coke should be the same as that of a normal coke batch, and the empty coke distribution matrix should be the same as that of a normal coke batch.

[0026] 3) According to the volume of the furnace waist, first load half of the volume of light-loaded materials, and then add a batch of empty coke. The mass of the empty coke is the same as the normal coke batch weight, and the empty coke distribution matrix is also the same as the normal coke batch. Then continue to load light-loaded materials until the furnace waist area is full. 4) Starting from the upper edge of the furnace waist and ending at the lower edge of the furnace throat, divide the furnace body into three equal parts by height. According to the different elevations, they are respectively called the lower part of the furnace body, the middle part of the furnace body, and the upper part of the furnace body. First load half of the volume of light-loaded materials under the furnace body, and then add a batch of empty coke. The mass of the empty coke is the same as the normal coke batch weight, and the empty coke distribution matrix is also the same as the normal coke batch, and then continue to load light-loaded materials;

[0027] First, half of the volume of the furnace body is loaded with light-load material, and then a batch of empty coke is added. The mass of the empty coke is the same as that of the normal coke batch, and the empty coke distribution matrix is also the same as that of the normal coke batch. Then continue to load light-load material until the furnace body is full.

[0028] Only light load material is loaded into the furnace body until the throat material line, wherein the preset position of the throat material line is the same as that of normal smelting before the blast furnace is shut down.

[0029] After the blast furnace is added, the following conditions must be met: the slag binary basicity R2 ≤ 1.10. The flux dosage is calculated based on the planned basicity. No additional flux is required when adding empty coke. The [Si] content in the molten iron should be controlled at 0.30%-0.50%, and the [S] content in the molten iron should be controlled at 0.020%-0.045%.

[0030] A total of 94.2 tons of additional coke was added to the blast furnace, and full-air smelting was achieved four hours after blast restoration. The fourth furnace's molten iron temperature rose to 1518°C and returned to normal, 12 hours after blast restoration. Overall, the blast furnace blast restoration process was rapid and smooth, demonstrating that the blast furnace blast restoration solution facilitates blast furnace blast restoration.

[0031] The above is a specific introduction of the present invention, and the present invention is summarized below:

[0032] The light-load charge can be reduced or maintained at the same load as the normal charge before the blast furnace shutdown, depending on the furnace's operating conditions. The flux dosage is calculated based on the slag basicity. The slag binary basicity, R2, is ≤ 1.10. The molten iron content (Si) is controlled at 0.30%-0.50%, and the molten iron content (S) is controlled at 0.020%-0.045%.

[0033] The empty focus is added at the position:

[0034] The amount of empty coke added to each batch is between 1.0 and 1.5 times the amount of coke added before the wind-down period. The empty coke charged is entirely composed of dry-quenched coke with reasonable specifications. No additional flux is added when adding empty coke. The first batch of empty coke is charged into the middle of the furnace belly. The second batch is charged into the middle of the furnace waist. The third batch is charged into the lower part of the furnace body. The fourth batch is charged into the middle of the furnace body.

[0035] Through one or more embodiments of the present invention, the present invention has the following obvious effects or advantages.

[0036] The present invention discloses a method for loading long-term blast-shutdown materials. The blast-shutdown materials include the loading amount and loading position of empty coke and light-loaded materials. When loading the light-loaded materials, the reduction in the load of the normal furnace charge before the blast-shutdown can be determined based on the furnace condition before the blast-shutdown. Dry-quenched coke is added to the empty coke section. No additional empty coke is added to the lower edge of the furnace bosh and the area below it. Only a batch of empty coke is added to the middle and upper soft melting zones of the furnace bosh. A batch of empty coke is added to the lower and middle parts of the furnace body.

[0037] After the blast furnace is charged, the following conditions must be met: slag binary basicity R2 ≤ 1.10, hot metal [Si] controlled at 0.30%-0.50%, hot metal [S] controlled at 0.020%-0.045%. The hot metal [Si] of the previous furnace must be controlled at 0.50%-0.70%, and the physical heat must be ≥ 1510°C. The furnace top temperature must be ≥ 120°C.

[0038] The total amount of additional coke added in the blast-out material is less than the conventional blast-out material amount. The furnace temperature and air volume recover quickly after re-airing. The blast furnace re-airing process is fast and smooth. The blast-out material program can promote the re-airing of the blast furnace.

[0039] It should be noted that the above embodiments are not intended to limit the scope of protection of the present invention, and equivalent changes or substitutions made on the basis of the above technical solutions fall within the scope of protection of the claims of the present invention.

Claims

1. A method for adding blast furnace blast material before long-term blast shutdown, characterized in that: The method comprises the following steps: The wind-shutdown materials include light-load materials and empty coke. The amount of empty coke added in each batch is between 1.0-1.5 times of the coke batch before the wind-shutdown. The loaded empty coke is all composed of dry-quenched coke with reasonable indicators. The first batch of empty coke is loaded into the middle of the furnace belly, the second batch of empty coke is loaded into the middle of the furnace waist, the third batch of empty coke is loaded into the lower part of the furnace body, and the fourth batch of empty coke is loaded into the middle of the furnace body.

2. The method for adding blast furnace blast material before long-term blast shutdown according to claim 1, characterized in that: After the wind-down material is loaded, the following conditions must be met: slag binary basicity R2≤1.10, control [Si] in molten iron: 0.30%-0.50%, [S] in molten iron: 0.020%-0.045%, control [Si] in the molten iron before wind-down: 0.50%-0.70%, physical heat ≥1510℃, furnace top temperature ≥120℃.

3. The method for adding blast furnace blast material before long-term blast shutdown according to claim 1, characterized in that: In the bosh area, light-load materials are added first according to the volume of the bosh area. The light-load materials fill half of the bosh volume, and then a batch of empty coke is added. Then light-load materials are added, and finally a batch of empty coke is added to fill the bosh area.

4. The method for adding blast furnace blast material before long-term blast shutdown according to claim 1, characterized in that: In the furnace waist area, first load half of the furnace waist volume with light-load material, then load a batch of empty coke, and finally fill the furnace waist with light-load material.

5. The method for adding blast furnace blast material before long-term blast shutdown according to claim 1, characterized in that: The furnace body is divided into three equal parts by height from the upper edge of the furnace waist to the lower edge of the furnace throat. According to different elevations, they are respectively called the lower furnace body, the middle furnace body and the upper furnace body. First, half of the volume of light-load material is loaded under the furnace body, and then a batch of empty coke is added, and then light-load material is continued to be loaded until the lower furnace body is full.

6. The method for adding blast furnace blast material before long-term blast shutdown according to claim 1, characterized in that: First, load half of the volume of the furnace body with light-load material, then add a batch of empty coke, and then continue to load light-load material until the furnace body is full. Only light-load material is loaded into the furnace body until the throat material line. The preset position of the throat material line is the same as that of normal smelting before the blast furnace is shut down.