A method for tapping a converter and a powder injection device for tapping a converter
By injecting a mixture of waste particles from ladle lining removal and coke powder into the converter during the steel tapping process, and controlling the injection amount, the problem of high FeO content in the slag at the converter endpoint is solved by using carbon to replace FeO in the slag, thereby increasing steel output and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANDONG IRON & STEEL CO LTD
- Filing Date
- 2024-08-14
- Publication Date
- 2026-05-15
AI Technical Summary
The high FeO content in the final slag of the converter leads to severe loss of iron elements in the slag, poor slag splashing effect, and increased costs.
During the converter tapping process, the FeO content of the slag at the end point is detected. A mixture of scrap particles from the removal of waste materials and coke powder is injected into the ladle lining. The injection amount is controlled, and carbon is used to replace FeO in the slag to generate Fe and CO2, thereby reducing iron loss and increasing the tapping rate.
It reduced production costs, improved slag splashing effect and furnace operation stability, and increased steel output.
Smart Images
Figure CN118853994B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of metallurgical technology, and more specifically, to a converter tapping method and a powder injection device for converter tapping. Background Technology
[0002] Due to the limitations of smelting low-carbon steel grades and the precision required for final control, the FeO content in the slag at the converter tapping stage is generally high. To reduce the FeO content in the converter slag at the final tapping stage, most steel mills currently employ measures such as high-flow-rate bottom blowing and top blowing nitrogen at the converter tapping stage. However, because of the strong oxidizing atmosphere inside the converter at the final tapping stage, the reduction in FeO in the slag after implementing these measures is minimal, and the FeO content in the slag remains high across multiple heats, leading to significant iron loss from the slag and a substantial impact on cost reduction. Furthermore, the high FeO content in the converter slag at the final tapping stage results in a prolonged slag splashing time after tapping, leading to higher nitrogen consumption and less effective slag splashing.
[0003] In summary, how to effectively solve the problem of high FeO content in the final slag of converters is a problem that needs to be solved by those skilled in the art. Summary of the Invention
[0004] In view of this, the purpose of the present invention is to provide a converter tapping method and a converter tapping powder injection device, which can effectively solve the problem of high FeO content in the slag at the converter end point.
[0005] To achieve the above objectives, the present invention provides the following technical solution:
[0006] A converter tapping method includes:
[0007] The FeO content of the slag was measured at the final stage after carbon removal from the converter.
[0008] When the converter taps out steel, a mixture of scrap particles from the removal of the ladle lining and coke powder is injected into the upper part of the slag inside the converter, and the amount of the mixture injected is controlled.
[0009] The injection amount satisfies the following formula:
[0010] Injection amount = Total slag amount * (Endpoint slag FeO content - Target slag FeO content) * (Fe molecular weight / FeO molecular weight) / Carbon molecular weight / Mass percentage of carbon in the mixture.
[0011] Optionally, the above-mentioned converter tapping method further includes:
[0012] Crushing involves crushing the waste material from the removal of the ladle lining.
[0013] Screening involves screening the crushed material.
[0014] Mix the screened material with a particle size of 5 mm or less with the coke powder, and then crush and screen the remaining part again.
[0015] Optionally, in the above converter tapping method, the ratio of the screened material to the coke powder is (0.9~1.1):(1.1~0.9).
[0016] Optionally, in the above-mentioned converter tapping method, the mixture comprises, by weight fraction: 38-42% carbon, 9-11% magnesium oxide, 28-32% aluminum oxide and 4-6% silicon dioxide, with the balance being impurities, and the sum of the contents of each component is 100%.
[0017] Optionally, in the above-mentioned converter tapping method, the mixture of ladle lining removal scrap particles and coke powder is sprayed into the upper part of the slag inside the converter, specifically including:
[0018] After the first preset time for tapping steel from the converter, a mixture of waste particles from the removal of the ladle lining and coke powder is sprayed into the upper part of the slag inside the converter until the second preset time for tapping steel from the converter, at which point the spraying of the mixture is stopped.
[0019] Optionally, in the above converter tapping method, the first preset time ranges from 8 to 12 seconds; the second preset time ranges from 160 to 200 seconds.
[0020] Optionally, in the above-mentioned converter tapping method, a powder injection device is used to inject the mixture into the upper part of the slag inside the converter. The powder injection device includes a mixing hopper, a blowing pipe, and a moving mechanism. The mixing hopper is used to mix the waste particles from the removal of the ladle lining with coke powder. The inlet of the blowing pipe is connected to the mixing hopper, and the outlet is located inside the converter to inject the mixture into the slag inside the converter. The moving mechanism is connected to the blowing pipe to drive the blowing pipe to move horizontally during injection.
[0021] Optionally, the above-mentioned converter tapping method further includes:
[0022] Calculate the injection amount corresponding to different endpoint FeO contents of the slag under a certain total slag amount and target slag FeO content, generate and store a model of endpoint slag FeO content and corresponding injection amount;
[0023] When the converter taps steel, the model is read, and the corresponding injection amount is determined based on the current FeO content of the final slag.
[0024] Optionally, the above-mentioned converter tapping method further includes:
[0025] Before the steel is tapped from the converter, a protective gas is injected into the converter.
[0026] To achieve the above objectives, the present invention also provides a powder injection device for converter tapping, used in any of the converter tapping methods described above, the powder injection device comprising:
[0027] The mixing hopper is used to mix the waste particles from the removal of the ladle lining with coke powder.
[0028] A blowpipe, the inlet of which is connected to the mixing hopper, and the outlet of which is located inside the converter to blow the mixture into the slag inside the converter;
[0029] A moving mechanism is connected to the blowpipe to drive the blowpipe to move horizontally.
[0030] The converter tapping method and powder injection device provided by this invention involve injecting a mixture of ladle lining removal waste particles and coke powder into the upper part of the slag inside the converter during tapping. The injection rate of the mixture is controlled by detecting the FeO content of the final slag after carbon removal in the converter. Based on the FeO content of the final slag, the total amount of slag, and the target FeO content of the slag, the corresponding injection rate is calculated. By injecting the mixture of ladle lining removal waste and coke powder during converter tapping, the carbon in the mixture replaces the iron in the slag, reducing the loss of iron elements in the slag. This increases the tapping rate, shortens the slag splashing time, and improves the slag splashing effect, which is beneficial for reducing production costs and improving the stability of the furnace operation. Attached Figure Description
[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0032] Figure 1 This is a schematic flowchart of a converter tapping method according to a specific embodiment of the present invention. Detailed Implementation
[0033] This invention discloses a converter steel tapping method and a powder injection device for converter steel tapping, which reduces the FeO content in the slag at the converter endpoint, shortens the slag splashing time, thereby reducing nitrogen consumption, improving the slag splashing effect, and increasing the steel tapping rate.
[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0035] In one specific embodiment, please refer to Figure 1 The converter tapping method provided by the present invention includes the following steps:
[0036] S1: Detection of FeO content in slag at the endpoint after carbon removal from the converter;
[0037] S2: When tapping steel from the converter, a mixture of scrap particles from the removal of the ladle lining and coke powder is injected into the upper part of the slag inside the converter, and the amount of mixture injected is controlled.
[0038] The injection volume satisfies the following formula:
[0039] Injection amount = Total slag amount * (Endpoint slag FeO content - Target slag FeO content) * (Fe molecular weight / FeO molecular weight) / Carbon molecular weight / Mass percentage of carbon in the mixture.
[0040] In this application, during the converter tapping process, a mixture of ladle lining removal waste particles and coke powder is injected. Ladle lining removal waste refers to the waste material formed after removing the ladle lining. When conventional ladle linings no longer meet the requirements for ladle use due to erosion or other reasons during steelmaking, the ladle lining needs to be removed and rebuilt. The removed ladle lining waste is usually disposed of directly or can be reprocessed for ladle rebuilding, but this has a certain impact on the quality stability of the ladle lining and the quality of the molten steel. Therefore, the amount added is usually small, meaning that most of the removed ladle lining material is discarded. The main component of coke powder is carbon. Specifically, coke powder from coking dust removal can be used, thus achieving the reuse of coking dust removal coke powder, further reducing costs and improving energy efficiency. The inventors of this application discovered that, due to the high reactivity of carbon, when coke powder is directly injected into the converter during the steelmaking process, the carbon is easily oxidized in the air and cannot react with the slag. This means the coke powder cannot fully react with the slag, resulting in poor injection efficiency. Furthermore, because coke powder is in powder form, it easily solidifies and clumps after being injected into the converter, further affecting its reaction with the slag. Therefore, this application uses granules from the waste material removed from the ladle lining, mixed with the coke powder. This prevents the coke powder from solidifying and clumping, and also prevents it from oxidizing and deteriorating during injection. This ensures that the coke powder is fully injected into the converter and reacts with the slag, and also enables the reuse of the waste material from the ladle lining removal, reducing production costs.
[0041] Specifically, the carbon in the mixture can react with FeO in the slag during the steelmaking process, as shown in the following reaction formula:
[0042] 2FeO + C = 2Fe + CO2
[0043] Compared to the conventional method of reducing FeO content in the final slag by reducing oxides, this application adds the reduction of FeO in the slag during the tapping process to the traditional method. That is, the carbon in the mixture is used to reduce FeO in the slag, so that FeO in the slag is reduced to Fe, thereby increasing the steel output.
[0044] The small amount of Fe2O3 in the slag can also react with the carbon in the mixture, as shown in the following reaction formula:
[0045] 2Fe₂O₃ + 3C = 4Fe + 3CO₂
[0046] It is evident that the carbon in the mixture can reduce FeO in the slag to Fe, and can also reduce Fe2O3 in the slag to Fe, thereby increasing the steel output.
[0047] Since the iron oxide in the slag is mainly FeO, this embodiment uses the FeO content as a reference to calculate the injection amount of the mixture. This satisfies the injection amount requirement while requiring less computation, facilitating automatic control. The specific injection amount of the mixture is calculated using the formula described above. The calculation principle is based on the replacement of iron elements in FeO from FeO in the slag by carbon elements in the mixture. The planned replacement amount of iron elements in the slag is calculated theoretically, and the injection amount is determined by the carbon content and the carbon-iron molecular weight ratio in the mixture. In the formula, the endpoint slag FeO content is the endpoint slag FeO content obtained after carbon removal in the converter. The specific method for determining the endpoint slag FeO content can refer to the relevant determination methods in conventional converter steelmaking processes, which will not be elaborated here. The target slag FeO content is the expected endpoint slag FeO content obtained after carbon removal in the converter steelmaking process, which can be determined by product or process requirements. The molecular weight of Fe can be calculated as 56, the molecular weight of FeO as 72, and the molecular weight of carbon as 12. The mass percentage of carbon in the mixture can be calculated based on the mixture's proportions, or it can be obtained through testing the mixture. The total amount of slag can be determined by process requirements, and its setting principle can be consistent with that in conventional converter steelmaking processes.
[0048] Understandably, for the same process, i.e., the total amount of slag is the same and the target slag FeO content is the same, the correspondence between the FeO content of the slag at different endpoints and the amount of powder injected can be calculated in real time during the tapping process, and the powder injection can be controlled according to the calculated injection amount. Alternatively, it can be calculated in advance and stored, and the corresponding powder injection amount can be read and controlled during the tapping process.
[0049] The converter tapping method and powder injection device provided by this invention involve injecting a mixture of ladle lining removal scrap and coke powder into the upper part of the slag inside the converter during tapping. The injection rate is controlled by detecting the FeO content of the final slag after carbon removal in the converter. Based on the FeO content of the final slag, the total slag volume, and the target FeO content, the corresponding injection rate is calculated. By injecting the mixture of ladle lining removal scrap and coke powder during converter tapping, the carbon in the mixture replaces the iron in the slag, reducing iron loss from the slag. This increases the tapping rate, shortens the slag splashing time, and improves the slag splashing effect, which is beneficial for reducing production costs and improving the stability of the furnace operation.
[0050] In some embodiments, the converter tapping method further includes:
[0051] Crushing involves crushing the waste material from the removal of the ladle lining.
[0052] Screening involves screening the crushed material.
[0053] Mix the screened material with a particle size of 5 mm or less with coke powder, and then crush and screen the remaining material again.
[0054] This converter tapping method also includes the pre-preparation of a mixture. Specifically, the waste material from the removal of the ladle lining is first crushed, and then screened. The screened material that meets the requirements is mixed with coke powder. The remaining material is crushed again, screened again, and the screened material that meets the requirements is mixed with coke powder, and this process is repeated. Through screening and filtration, ladle lining removal waste particles with a particle size of less than or equal to 5 mm can be obtained. Mixing this with coke powder can effectively prevent the coke powder from solidifying and agglomerating, and from oxidizing and deteriorating during the injection process, ensuring that the coke powder is injected into the converter and reacts fully with the slag.
[0055] In some embodiments, the mixing ratio of screened material to coke powder is (0.9~1.1):(1.1~0.9), specifically 1:1. Controlling the ratio of screened material to coke powder within the above range can effectively utilize the screened material, allowing the coke powder to adhere to the screened material and between the screened materials, preventing the coke powder from solidifying and agglomerating, and from oxidizing and deteriorating during the injection process. This ensures that the coke powder is injected into the converter and reacts fully with the slag.
[0056] In some embodiments, the mixture comprises, by weight fraction: 38-42% carbon, 9-11% magnesium oxide, 28-32% aluminum oxide, and 4-6% silicon dioxide, with the balance being impurities, and the sum of the contents of each component is 100%. That is, the mixture comprises, by weight fraction: 38-42% C, 9-11% MgO, 28-32% Al₂O₃, 4-6% SiO₂, with the balance being impurities. The carbon in the mixture is mainly used to react with iron oxides in the slag to reduce them to iron. The scrap from the removal of the ladle lining mainly includes magnesium oxide and aluminum oxide. Magnesium oxide can improve the fluidity of the slag and prevent slag crusting, thereby increasing the reaction efficiency between the carbon in the mixture and the slag, thus more effectively increasing the steel output. Alumina plays a role in protecting the furnace. Controlling the composition of the mixture within the above range can improve the reaction efficiency between the mixture and the slag, thereby increasing the steel output.
[0057] In some embodiments, a mixture of ladle lining removal waste particles and coke powder is injected into the upper part of the slag in the converter. Specifically, this includes: after a first preset time of converter tapping, the mixture of ladle lining removal waste particles and coke powder is injected into the upper part of the slag in the converter until a second preset time of converter tapping, at which point the injection of the mixture stops. That is, during converter tapping, the mixture is added after the first preset time of tapping, and the addition of the mixture is stopped before the converter stops tapping. Because the molten steel and slag are unstable at the beginning of the converter tapping process, even if the mixture is added, the reaction efficiency between the slag and the mixture is relatively low. Therefore, the mixture is not added initially, but only after the first preset time, when the state of the molten steel and slag is more stable, to allow the mixture to react fully with the slag. In addition, near the end of tapping, the reaction time between the injected mixture and the slag is relatively short, so the mixture and slag do not react fully before tapping is completed. Therefore, the addition of the mixture should be stopped a certain time before the end of tapping, that is, the injection of the mixture should be stopped at the second preset time of tapping. This can give full play to the role of the mixture, allow it to react fully with the slag, and improve the utilization rate of the mixture.
[0058] In some embodiments, the first preset time ranges from 8 to 12 seconds; the second preset time ranges from 160 to 200 seconds. Specifically, the first preset time is 10 seconds; the second preset time ranges from 180 seconds. That is, 10 seconds after the converter taps steel, a mixture of ladle lining removal scrap particles and coke powder is injected into the upper part of the slag inside the converter until 180 seconds after the converter taps steel, at which point the injection of the mixture stops. If the first preset time is short, the reaction efficiency between the newly added mixture and the slag is low; if the first preset time is long, the reaction time between the mixture and the slag is short. Similarly, if the second preset time is short, the reaction time between the mixture and the slag is short; conversely, if the second preset time is long, the later-added mixture does not have enough time to fully react with the slag before the steel tapping ends. Therefore, setting the first and second preset times as described above can fully utilize the role of the mixture, ensure a thorough reaction with the slag, and improve the utilization rate of the mixture.
[0059] In some embodiments, a powder injection device is used to inject a mixture into the upper part of the slag in the converter. The powder injection device includes a mixing hopper, a blowing pipe, and a moving mechanism. The mixing hopper is used to mix the waste particles from the removal of the ladle lining with coke powder. The inlet of the blowing pipe is connected to the mixing hopper, and the outlet is located inside the converter to inject the mixture into the slag. The moving mechanism is connected to the blowing pipe to drive the blowing pipe to move horizontally during injection. The mixing hopper can hold the waste particles from the removal of the ladle lining and coke powder, and can also mix the two. The blowing pipe is used to inject the mixture from the mixing hopper into the converter. Since the slag surface area is large during the converter tapping process, the powder injection device, by setting a moving mechanism, can drive the blowing pipe to move horizontally, and the outlet of the blowing pipe moves horizontally accordingly. This allows the mixture to be uniformly injected into the slag in a horizontal plane, increasing the contact area between the mixture and the slag, thereby increasing the reaction rate and amount of carbon in the mixture with FeO in the slag.
[0060] In some embodiments, the mixing hopper includes a hopper body and a stirring blade disposed within the hopper body. The stirring blade is connected to a drive component, which drives the stirring blade to rotate, thereby agitating the ladle lining removal waste particles and coke powder within the hopper body to ensure uniform mixing. The drive component can specifically be a motor. The bottom of the mixing hopper has an outlet that communicates with the inlet of a blowpipe. The outlet is equipped with a valve, which is opened after the ladle lining removal waste particles and coke powder have been uniformly mixed to deliver the mixture within the hopper body into the blowpipe. The mixing hopper is also equipped with a weighing device for weighing the mixture. The valve is closed when the reduction in the weight of the mixture measured by the weighing device equals the amount of material injected. The outlet of the blowpipe is located above the converter to inject the mixture into the slag within the converter. The blowpipe is connected to a blower to blow the mixture within the blowpipe into the top of the converter. The moving mechanism includes an XY-axis motion platform for moving the blowpipe in a horizontal plane. With the above settings, the amount of mixture injected can be precisely controlled, and the valves, weighing devices, and XY axis motion platforms can be electrically connected to the controller. The controller controls the valves, weighing devices, and XY axis motion platforms to achieve automatic control of the addition of mixture during the steel tapping process.
[0061] In some embodiments, the converter tapping method further includes:
[0062] Calculate the injection amount corresponding to different endpoint FeO contents of slag under a certain total slag amount and target slag FeO content, generate and store the model of endpoint slag FeO content and corresponding injection amount;
[0063] When tapping steel from the converter, the model is read, and the corresponding injection amount is determined based on the current FeO content in the final slag.
[0064] In a converter steelmaking process, if the target slag FeO content and the total slag volume are determined, the injection amount corresponding to each endpoint slag FeO content can be calculated using the injection amount calculation formula. A model is then generated and stored for different injection amounts corresponding to different endpoint slag FeO contents. Subsequently, during converter tapping, this model can be directly read to determine the corresponding injection amount based on the detected current endpoint slag FeO content, and this is used for mixed material injection control. The aforementioned model can specifically be a data table. In other embodiments, the corresponding injection amount can also be calculated in real time based on parameters such as the detected current endpoint slag FeO content, target slag FeO content, and total slag volume. Taking a total slag volume of 7.5t as an example, the model of endpoint slag FeO content and corresponding injection amount is shown in Table 1.
[0065] Table 1. Model of FeO content in final slag versus injection amount (total slag amount: 7.5t)
[0066] Final furnace FeO content Target FeO content in slag Injection volume, kg 9.5% 8% 18.23±3 10.0% 8% 24.31±3 10.5% 8% 30.38±3 11.0% 8% 36.46±3 11.5% 8% 42.53±3 12.0% 8% 48.61±3 12.5% 8% 54.69±3 13.0% 8% 60.76±3 13.5% 8% 66.84±3 14.0% 8% 72.92±3 14.5% 8% 78.99±3 15.0% 8% 85.07±3 15.5% 8% 91.15±3 16.0% 8% 97.22±3
[0067] In some embodiments, the converter tapping method further includes: injecting a protective gas into the converter before tapping. By injecting a protective gas into the converter, oxidation is reduced, thereby lowering the FeO content in the final slag and increasing the tapping rate.
[0068] The following is a comparative description using a specific embodiment and a comparative example.
[0069] Example 1
[0070] The above-mentioned converter tapping method was used to control the tapping of 150t converter steel.
[0071] Heater 1: This heat smelted HRB400E-1 steel with a hot metal charge of 130t, a silicon content of 0.36%, a manganese content of 0.30%, 30t of scrap steel, and 2200kg of slag. During smelting, 2800kg of lime and 1200kg of dolomite were added. There was no slag overflow. After carbon removal from the converter, the final carbon content was 0.10%, and the target slag FeO content was 13%. Other control parameters met the steel grade tapping requirements. Direct tapping was performed. 10 seconds into tapping, a mixture of 60.76kg of ladle lining scrap and coking dust was sprayed into the upper part of the converter slag. During tapping, 2900kg of silicon-manganese alloy and 100kg of carbon raiser were added. The spraying of the mixture was stopped after 180 seconds of tapping. After tapping, the molten steel weighed 157.10t. 2250m³ of nitrogen was used for slag splashing. 3 .
[0072] Comparative Example 1
[0073] The conventional existing methods are used to control the tapping of steel from a 150t converter.
[0074] Heater 1: This heat smelted HRB400E-1 steel. The hot metal charge was 130t, with a silicon content of 0.36% and a manganese content of 0.30%. 30t of scrap steel was added, and 2200kg of slag was left over. During the smelting process, 2800kg of lime and 1200kg of dolomite were added. There was no slag overflow. After carbon removal from the converter, the final carbon content was 0.10%, and the target slag FeO content was 13%. Other control parameters met the steel grade's tapping requirements. The steel was tapped directly. During tapping, 2900kg of silicon-manganese alloy and 100kg of carbon raiser were added. After tapping, the molten steel weighed 156.99t. 3000m³ of nitrogen was used for slag splashing. 3 .
[0075] The examples and comparative examples were compared, and the results are shown in Table 2.
[0076] Table 2 Comparison of Input and Output Costs of Pulverized Materials
[0077] Case Example 1 Comparative Example 1 Coke powder quantity, kg 30.38 0 Coke powder price, yuan / kg 0.8 0 Steel ladle lining scrap amount, kg 30.38 0 Steel ladle lining scrap and processing costs, yuan / kg 0.3 0 Pulse-jet operating cost: yuan / kg 0.05 0 Steel output, t 157.1 156.99 Steel material price, yuan / ton 2800 2800 Total output cost, yuan 439843.54 439572
[0078] Compared with Comparative Example 1, Example 1 increased the cost by 271.54 yuan, but increased the steel output by 110 kg. This shows that the steel output was increased while the cost difference was minimal.
[0079] Based on the converter tapping method provided in the above embodiments, the present invention also provides a powder injection device for converter tapping, which is used in any of the converter tapping methods described in the above embodiments. The powder injection device for converter tapping includes a mixing hopper, a blowing pipe, and a moving mechanism. The mixing hopper is used to mix the ladle lining removal waste particles with coke powder. Specifically, the powder injection device can be installed above the tapping side. The mixing hopper can hold the ladle lining removal waste particles and coke powder, and also mix them. Specifically, the mixing hopper includes a hopper body and stirring blades disposed within the hopper body. The stirring blades can be connected to a driving component such as a motor. The driving component drives the stirring blades to rotate, thereby agitating the ladle lining removal waste particles and coke powder within the hopper body to ensure uniform mixing. The bottom of the mixing hopper has an outlet that communicates with the inlet of the blowing pipe, and the outlet is equipped with a valve. After the ladle lining removal waste particles and coke powder are uniformly mixed, the valve opens, allowing the mixture within the hopper body to enter the blowing pipe. The outlet of the injection pipe is located inside the converter to inject the mixture into the slag. Specifically, the injection pipe can be connected to equipment such as a blower that provides injection gas to blow the mixture into the upper part of the converter. A moving mechanism is connected to the injection pipe to drive its horizontal movement. On the one hand, the moving mechanism drives the injection pipe horizontally; on the other hand, it provides support for the injection pipe.
[0080] The powder injection device for converter tapping provided by this invention can inject a mixture of granules from the ladle lining removal waste and coke powder into the upper part of the slag in the converter during tapping. By controlling the injection amount of the mixture, carbon in the mixture replaces iron in the slag, reducing the loss of iron in the slag. This increases the tapping rate, shortens the slag splashing time, and improves the slag splashing effect, which is beneficial for reducing production costs and improving the stability of the furnace operation.
[0081] In addition, since the slag surface area is large during the converter tapping process, the powder injection device can drive the injection pipe to move horizontally by setting a moving mechanism. The outlet of the injection pipe moves horizontally accordingly, so that the mixture can be uniformly injected into the slag in the horizontal plane, increasing the contact area between the mixture and the slag, thereby increasing the reaction rate and amount of carbon in the mixture with FeO in the slag.
[0082] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0083] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for tapping steel from a converter, characterized in that, include: The FeO content of the slag was measured at the final stage after carbon removal from the converter. During the tapping process, a mixture of scrap particles from the ladle lining removal and coke powder is injected into the upper part of the slag inside the converter. The carbon in the mixture reacts with the FeO in the slag during the tapping process, and the amount of the mixture injected is controlled. The injection amount satisfies the following formula: Injection rate = Total slag (Endpoint FeO content in slag - Target FeO content in slag) (Fe molecular weight / FeO molecular weight) / carbon molecular weight / mass percentage of carbon in the mixture; The mixture of waste particles from the removal of the ladle lining and coke powder is sprayed into the upper part of the slag inside the converter, specifically including: After the first preset time for tapping steel from the converter, a mixture of steel ladle lining removal waste particles and coke powder is sprayed into the upper part of the slag inside the converter until the second preset time for tapping steel from the converter, at which point the spraying of the mixture is stopped. The mixture comprises, by weight fraction: 38-42% carbon, 9-11% magnesium oxide, 28-32% aluminum oxide and 4-6% silicon dioxide, with the balance being impurities, and the sum of the contents of each component is 100%.
2. The converter tapping method according to claim 1, characterized in that, Also includes: Crushing involves crushing the waste material from the removal of the ladle lining. Screening involves screening the crushed material. Mix the screened material with a particle size of 5 mm or less with the coke powder, and then crush and screen the remaining part again.
3. The converter tapping method according to claim 2, characterized in that, The ratio of the screened material to the coke powder is (0.9~1.1):(1.1~0.9).
4. The converter tapping method according to claim 1, characterized in that, The first preset time ranges from 8 to 12 seconds; the second preset time ranges from 160 to 200 seconds.
5. The converter tapping method according to any one of claims 1-4, characterized in that, A powder injection device is used to inject the mixture into the upper part of the slag inside the converter. The powder injection device includes a mixing hopper, a blowing pipe, and a moving mechanism. The mixing hopper is used to mix the waste particles from the removal of the ladle lining with coke powder. The inlet of the blowing pipe is connected to the mixing hopper, and the outlet is located inside the converter to inject the mixture into the slag inside the converter. The moving mechanism is connected to the blowing pipe to drive the blowing pipe to move horizontally during injection.
6. The converter tapping method according to any one of claims 1-4, characterized in that, Also includes: Calculate the injection amount corresponding to different endpoint FeO contents of the slag under a certain total slag amount and target slag FeO content, generate and store a model of endpoint slag FeO content and corresponding injection amount; When the converter taps steel, the model is read, and the corresponding injection amount is determined based on the current FeO content of the final slag.
7. The converter tapping method according to claim 1, characterized in that, Also includes: Before the steel is tapped from the converter, a protective gas is injected into the converter.