Smelting method for directly recycling 120-ton converter dry dedusting coarse particles to converter

Abstract

The invention discloses a smelting method for directly recycling 120-ton converter dry dedusting coarse particles to a converter. The method comprises the following steps: after slag splashing of steel on a converter is finished, shaking the converter to 90-120 degrees for slag spreading operation, and simultaneously reducing the air speed of a primary dust removal fan of the converter to be below 700 revolutions per minute; the converter is shaken to the temperature of 45-55 DEG C, 15-25 tons of waste steel is added, after the waste steel is added, the converter is shaken to the zero position, and 500-1000 kg of converter dry dedusting coarse particles are added; the wind speed of the dust removal fan is increased to gt; the rotation speed is 1400 r / min; shaking the converter to the tapping surface to-20 DEG C to-40 DEG C, and spreading out the dry dedusting coarse particles of the converter again; and the converter is shaken to 40-50 DEG C, 105-115 tons of molten iron is added, and after iron adding is completed, the converter is shaken to the zero position, and then blowing is started. The method effectively solves the technical problem of foam splashing in the earlier stage of converter smelting caused by direct recycling of the converter dry dedusting coarse particles, can meet the steel grade process requirements, can reduce cost, improve efficiency, save energy, reduce consumption and reduce waste emission, and has good popularization and application values.

Description

Technical Field

[0001] The invention belongs to the technical field of converter smelting, and in particular relates to a smelting method in which coarse particles of a 120-ton converter are directly recycled into the converter by dry-dusting. Background Art

[0002] A large amount of solid waste is generated during the converter steelmaking process, including coarse ash from the converter dry dust removal, which may pose a threat to the environment and may also be transformed into a valuable non-renewable resource. Its comprehensive utilization and disposal have always been a major issue facing steel companies. Turning waste into treasure can not only protect the ecological environment and reduce the problem of stacking sites, but also effectively utilize the useful resources, reduce production costs, create value, and achieve clean production. This has very important practical significance for promoting enterprise upgrading and transformation, achieving the "dual carbon" goal, and improving enterprise efficiency and benefits.

[0003] The current main use status of converter dry dust removal coarse ash is as follows: 1. Hot briquetting method: Heat the coarse ash and fine ash from the dry dust removal of the converter, use its plasticity at high temperature to press it into briquettes through a high-pressure briquetting machine, and then cool it in a nitrogen-sealed state and transport it to the converter to replace scrap steel or ore. This method requires the establishment of new workshops and equipment, as well as the transportation and storage of coarse ash.

[0004] 2. Cold briquetting method: Add some additives to the coarse ash and sludge from dry dust removal, and make converter slag-making agent briquettes through cold solidification process, which are used for converter slag making, improving the dephosphorization effect and dephosphorization rate. This method requires the establishment of new plant and equipment, and also requires the transportation and storage of coarse particles.

[0005] 3. Add sintering mixture, add sintering mixture, sinter and then enter the ironmaking blast furnace for circulation. Although this method does not require additional equipment, it removes coarse particles of harmful impurities, and sintering is difficult to effectively remove these impurities. This makes sintering and stable operation difficult. After entering the blast furnace, it will affect the normal operation of the blast furnace and the life of the furnace lining.

[0006] 4. The slag is directly put into the converter for reuse. This method has the disadvantages of too much slag added in the early stage of converter smelting, slow temperature rise in the early stage, and high TFe content (50%) of coarse particles in the converter dry dust removal. The slag layer is thick in the early stage of converter smelting and low-temperature splashing is serious.

[0007] In view of the problems and shortcomings of the existing technology of coarse particles in dry dust removal of converters, a method of directly recycling coarse particles in dry dust removal of converters into the converter has been developed. This method has good promotion and application value in reducing costs, reducing waste emissions, reducing converter slag consumption, solving the serious splashing problem in the early stage of direct recycling of converters, and improving environmental safety production. Summary of the invention

[0008] The object of the present invention is to provide a smelting method in which coarse particles of dry dust removal from a converter are directly recycled into the converter.

[0009] The object of the present invention is achieved by a smelting method of a 120-ton converter dry dust removal coarse particles directly recycled to the converter, which is achieved by following the steps: 1) The coarse ash recycling system is used to transport the coarse particles of dry dust removal generated by the converter to the converter high-level silo for standby use; 2) After the slag splashing of the steel in the furnace is completed, the converter is shaken to 90°~120° for slag spreading, and the wind speed of the converter primary dust removal fan is reduced to below 700 rpm; 3) Shake the converter to 45°~55°, add 15~25 tons of scrap steel, after adding the scrap steel, shake the converter to the "zero" position, and add 500~1000 kg of coarse particles for dry dust removal of the converter; 4) After the coarsening of particles is completed, the dust removal fan speed is increased to >1400 rpm; 5) The converter is shaken to -20°~-40° toward the steel tapping surface, and the coarse particles of dry dust removal from the converter are spread out again; 6) The converter is tilted to 40°-50°, and 105-115 tons of molten iron is added. After the iron addition is completed, the converter is tilted to the "zero position" and then blowing begins; the blowing includes a slag pouring stage and a slag making stage.

[0010] The beneficial effects of the present invention are as follows: 1) The method of the present invention effectively solves the technical problem of foam splashing in the early stage of converter smelting caused by direct recycling of coarse particles removed by dry dust in the converter; 2) The method of the present invention can effectively utilize the free CaO and MgO in the upper furnace slag, remove a certain amount of P and 60% of Si, which is beneficial to reducing the slag amount and P removal load in the subsequent slag making process.

[0011] 3) The method of the present invention can recycle TFe (FeO, Fe2O3, MFe), MnO, CaO, MgO and the like in the coarse particles of dry dust removal of the converter; the coarse particles of dry dust removal of the converter are used as flux to promote the formation of initial slag of the converter, improve the slag-forming conditions of the converter, and increase the P removal rate of the converter.

[0012] 4) The smelting method of the present invention can not only meet the process requirements of steel grades, but also reduce costs, increase efficiency, save energy and reduce consumption, and reduce waste emissions, and has good promotion and application value. DETAILED DESCRIPTION

[0013] The present invention is further described below in conjunction with the embodiments, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention belong to the protection scope of the present invention.

[0014] The present invention provides a smelting method for directly recycling coarse particles of a 120-ton converter by dry dust removal to the converter, which is achieved by the following steps: 1) The coarse ash recycling system is used to transport the coarse particles of dry dust removal generated by the converter to the converter high-level silo for standby use; 2) After the slag splashing of the steel in the furnace is completed, the converter is shaken to 90°~120° for slag spreading, and the wind speed of the converter primary dust removal fan is reduced to below 700 rpm; 3) Shake the converter to 45°~55°, add 15~25 tons of scrap steel, after adding the scrap steel, shake the converter to the "zero" position, and add 500~1000 kg of coarse particles for dry dust removal of the converter; 4) After the coarsening of particles is completed, the dust removal fan speed is increased to >1400 rpm; 5) The converter is shaken to -20°~-40° toward the steel tapping surface, and the coarse particles of dry dust removal from the converter are spread out again; 6) The converter is tilted to 40°-50°, and 105-115 tons of molten iron is added. After the iron addition is completed, the converter is tilted to the "zero position" and then blowing begins; the blowing includes a slag pouring stage and a slag making stage.

[0015] In step 6), the blowing and slag pouring stage method is as follows: a. The oxygen gun automatically lowers to 2500mm and starts oxygen blowing automatically. The ignition flow rate is set to 380~430Nm 3 / min, the ignition gun position is set to 2000~2200mm; b. After ignition is normal, the oxygen gun position is set to 1800-2000mm, and the oxygen flow rate is set to 260-300Nm 3 / min, maintain this flow rate for 30-40s; if the oxygen pressure is less than 0.6MP for 20s, adjust the oxygen flow rate to 330-350Nm 3 / min, when the instantaneous oxygen pressure is >0.6MP, the oxygen flow rate is set to 260~300Nm 3 / min; c. Gradually increase the oxygen flow rate to 410-450 Nm 3 / min, oxygen supply reaches 700~1200Nm 3 , blowing is terminated, the furnace is emptied and the slag is poured out, 40-60% of the slag is poured out, and the furnace is shaken to the "zero" position.

[0016] In step 6), the blowing and slagging stage method is as follows: The converter is moved to the "zero" position, and the smelting is started. The oxygen lance automatically lowers to 2500mm and oxygen blowing is automatically started. The ignition flow rate is set to 380-430Nm 3 / min, the ignition gun position is set to 1600-2000mm, after successful ignition, the oxygen flow rate is adjusted to 410-450Nm3 / min, the gun position is adjusted to 1000-1400mm, and active lime and light-burned dolomite are added to make slag. The slag basicity is calculated as 1.5-2.5.

[0017] The mass ratio of active lime to light-burned dolomite is 0.8:1.2.

[0018] The first batch of slag is added at 60-80% of the total slag amount; after the initial slag is formed, the gun position and flow rate can be fine-tuned according to the slagging situation; when the initial slag is basically fully melted, add the remaining slag-making material.

[0019] During the smelting process, temperature regulating materials can be added in batches or at times to purify the steel particles at a high level according to the temperature.

[0020] When smelting is close to the end, the gun position is gradually lowered to 800-900mm, and the oxygen flow rate is 430-450Nm 3 / min control, end pressure time>30S.

[0021] The end point temperature of molten steel in converter smelting is controlled at 1640±10℃, the end point C is controlled at 0.06-0.12%, and the end point P / S is controlled at <0.03%. Example 1 This embodiment takes the 120t converter of Kunming Iron and Steel as an example, the smelting furnace number is 24F05777, and the steel grade is HRB400E.

[0022] 1. Use the elevator to transport the coarse particles of dry dust removal produced by the converter to the high-level silo of the converter for standby use; 2. After the slag splashing of the steel in the furnace is over, the converter is shaken to 115 degrees, and the residual slag is spread on the slag pouring surface. All the residual slag is left in the furnace. At the same time, the converter primary dust removal fan is "slowed down" to below 700 rpm; 3. The converter is shaken to 48° and 22 tons of scrap steel is added. After the scrap steel is added, the converter is shaken to the "zero" position and 890 kg of coarse particles for dry dust removal are added to the converter. After the coarse particles are added, the converter primary dust removal fan is started and "speeded up" to > 1400 revolutions; 4. The converter is rotated to -40° toward the steel tapping surface, and then to 50°, and 115 tons of molten iron is added. The molten iron temperature is 1364°C; the molten iron composition: C 4.88%, Si 0.83%, P 0.074%, S 0.027%. After the iron addition is completed, the converter is rotated to the "zero position".

[0023] 7. The first stage of converter smelting (slag pouring stage): Click to start smelting, the oxygen gun automatically lowers to the set gun position (2500mm), automatically starts oxygen blowing, and the ignition flow rate is set to 380Nm 3 / min, the ignition gun position is set to 2000mm; after normal ignition, the oxygen gun position is set to 1800mm, and the oxygen is set to 260Nm 3 / min, oxygen supply pressure 0.57MPa, oxygen supply 25S, oxygen flow rate setting 430Nm 3 / min, the oxygen supply pressure reaches 0.67MPa, and the oxygen flow rate is set to 260Nm 3 / min, keep this flow rate for 40s, oxygen flow rate 430Nm 3 / min, oxygen supply reaches 1020Nm 3 , blowing is terminated, the furnace is shaken to 78° and the slag is poured out. About 60% of the slag is poured out, and the furnace is shaken to the "zero" position.

[0024] 8. The second stage of converter smelting (slag-making stage): The converter is shaken to the "zero" position, and the smelting is started. The oxygen gun automatically lowers to the set gun position (2500mm) and automatically starts oxygen blowing. The ignition flow rate is set to 380Nm 3 / min, the ignition gun position is set to 1600mm, after successful ignition, the oxygen flow rate is adjusted to 430Nm 3 / min, the gun position is adjusted to 1400mm, and slag making is started. The first batch of active lime is added as 2010kg, light-burned dolomite is 1760kg, and oxygen is supplied for 420S. The gun position is adjusted to 1640mm, and 800kg of purified steel particles are added. Oxygen is supplied for 480S. The gun position is adjusted to 1580mm, and 510kg of active lime and 440kg of light-burned dolomite are added. Oxygen is supplied for 560s, and 600kg of purified steel particles are added. Smelting is carried out for 600S. The gun position is adjusted to 1440mm, and smelting is carried out for 630S. The gun position is adjusted to 1180mm, and smelting is carried out to 660S. The gun position is adjusted to 1060mm, and smelting is carried out to 690S. The gun position is adjusted to 796mm, and smelting is carried out to 730S, and the blowing is terminated. The furnace was turned down and temperature was measured and samples were taken. The endpoint temperature was 1650℃, endpoint C: 0.06%, endpoint P: 0.027%, and endpoint S: 0.027%.

[0025] 9. Converter endpoint control: The endpoint temperature is controlled at 1650℃, the endpoint C is controlled in the range of 0.06-0.12%, the endpoint P0.027%, and the endpoint S<0.027%, meeting the endpoint control requirements.

[0026] 10. Steel is tapped from the converter and deoxidized and alloyed according to the key points of steel grade control - argon blowing treatment of molten steel - molten steel is hoisted to continuous casting. The composition of molten steel is: C: 0.022%, Si: 0.46%, Mn: 1.37%, P: 0.030%, S: 0.032%. The process control requirements are met.

[0027] The economic benefits of Kunming Iron and Steel after adopting the smelting method of the present invention are as follows: 1. From January to May 2023, Kunming Iron and Steel produced 186.412 tons of high-P waste, with a high-P waste rate of 0.0168%. From June to December 2023, after the implementation of the direct recycling method of coarse particles from dry dust removal of converters of the present invention, 151.085 tons of high-P waste was produced, with a high-P waste rate of 0.0086%. The high-P waste rate was reduced by 0.0082%. From June to December 2023, 1,754,704.635 tons of steel was produced, which can reduce high-P waste by 143.7 tons. Calculated according to the processing fee of 462.09 yuan / ton, it can create economic benefits: 143.7×462.09=66,402.3 yuan.

[0028] From January to May 2023, 5403.72 tons of coarse particles were removed by dry dust removal in the reversing furnace of Kunming Iron and Steel Plant, with a ton of steel output of 4.87 kg / t. From June to December 2023, after the direct reuse method of coarse particles removed by dry dust removal of the converter of the present invention was implemented, 295.86 tons of coarse particles were removed by dry dust removal in the reversing furnace of the plant, with a ton of steel output of 0.15 kg / t, a reduction of 4.72 kg / t per ton of steel. From June to December 2023, 1,754,704.635 tons of steel was produced, and 8,282.2 tons of coarse particles were reduced by reversing. Calculated based on the reversing fee of 50 yuan / ton, the economic benefit created is: 50×8282.2=414,110 yuan.

[0029] Total economic benefits: 66402.3+414110=480512.3 yuan 2. From June to December 2023, the amount of coarse particles from the dry dust removal of the converter will be reduced by 8,282.2 tons in the factory, which is of great significance to the social benefits such as reducing the pressure of short-circuit in the factory, energy consumption and emissions of road transportation, and dust pollution during the transportation process.

Claims

1. A smelting method in which the coarse particles of dry dust removal from a 120-ton converter are directly recycled into the converter, characterized in that: Follow these steps to achieve this: 1) The coarse ash recycling system is used to transport the coarse particles of dry dust removal generated by the converter to the converter high-level silo for standby use; 2) After the slag splashing of the steel in the furnace is completed, the converter is shaken to 90°~120° for slag spreading, and the wind speed of the converter primary dust removal fan is reduced to below 700 rpm; 3) Shake the converter to 45°~55°, add 15~25 tons of scrap steel, after adding the scrap steel, shake the converter to the "zero" position, and add 500~1000 kg of coarse particles for dry dust removal of the converter; 4) After the coarsening of particles is completed, the dust removal fan speed is increased to >1400 rpm; 5) The converter is shaken to -20°~-40° toward the steel tapping surface, and the coarse particles of dry dust removal from the converter are spread out again; 6) The converter is tilted to 40°-50°, and 105-115 tons of molten iron is added. After the iron addition is completed, the converter is tilted to the "zero position" and then blowing begins; the blowing includes a slag pouring stage and a slag making stage.

2. The smelting method according to claim 1, characterized in that: In step 6), the blowing and slag pouring stage method is as follows: a. The oxygen gun automatically lowers to 2500mm and starts oxygen blowing automatically. The ignition flow rate is set to 380~430Nm 3 / min, the ignition gun position is set to 2000~2200mm; b. After ignition is normal, the oxygen gun position is set to 1800-2000mm, and the oxygen flow rate is set to 260-300Nm 3 / min, keep this flow rate for 30-40s; if the oxygen pressure is less than 0.6MP for 20s, adjust the oxygen flow rate to 330-350Nm 3 / min, when the instantaneous oxygen pressure is >0.6MP, the oxygen flow rate is set to 260~300Nm 3 / min; c. Gradually increase the oxygen flow rate to 410-450 Nm 3 / min, oxygen supply reaches 700~1200Nm 3 , blowing is terminated, the furnace is emptied and the slag is poured out, 40-60% of the slag is poured out, and the furnace is shaken to the "zero" position.

3. The smelting method according to claim 1, characterized in that: In step 6), the blowing and slagging stage method is as follows: The converter is moved to the "zero" position, and the smelting is started. The oxygen lance automatically lowers to 2500mm and oxygen blowing is automatically started. The ignition flow rate is set to 380~430Nm 3 / min, the ignition gun position is set to 1600~2000mm, after successful ignition, the oxygen flow rate is adjusted to 410~450Nm 3 / min, the gun position is adjusted to 1000-1400mm, and active lime and light-burned dolomite are added to make slag.

4. The smelting method according to claim 3, characterized in that: The mass ratio of active lime to light-burned dolomite is 0.8:1.

2.

5. The smelting method according to claim 3, characterized in that: The first batch of slag is added at 60-80% of the total slag amount; after the initial slag is formed, the gun position and flow rate can be fine-tuned according to the slagging situation; when the initial slag is basically fully melted, add the remaining slag-making material.

6. The smelting method according to claim 3, characterized in that: During the smelting process, temperature regulating materials can be added in batches or at times to purify the steel particles at a high level according to the temperature.

7. The smelting method according to claim 3, characterized in that: When smelting is close to the end point, the gun position is gradually lowered to 800-900mm, the oxygen supply flow rate is controlled at 430-450Nm3 / min, and the end pressure time is >30S.

8. The smelting method according to claim 1, characterized in that: The final temperature of molten steel in converter smelting is controlled at 1640±10℃, the final C is controlled at 0.06-0.12%, and the final P / S is controlled at <0.03%.