Process method for reducing converter blowing overflow slag
By injecting high-pressure nitrogen and optimizing oxygen supply, the problem of slag overflow in converter steelmaking was solved, efficient slag and iron separation was achieved, and the purity of molten steel and production efficiency were improved.
Patent Information
- Application Number
- CN202510294607.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-13
- Publication Date
- 2025-09-19
AI Technical Summary
During the converter steelmaking process, slag overflow frequently occurs in the early stages of blowing, resulting in a lack of metal in the finished molten steel. Multiple slag dumping operations also prolong production time and affect the working environment.
After blowing in the converter for 3-4 minutes, high-pressure nitrogen is injected to destroy the stability of the slag layer, causing the slag layer to break up and disperse, and to form tiny bubbles, reducing the encapsulation of iron beads. Slag-making materials and foam slag inhibitors are used to optimize oxygen supply and promote slag-iron separation.
Effectively reduce slag overflow, improve molten steel purity, avoid slag pouring operations, shorten production time, improve work efficiency, and reduce metal loss.
Smart Images
Figure CN120666138A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of steelmaking converter smelting, and in particular to a process method for reducing converter blowing slag overflow. Background Art
[0002] The converter is an essential piece of equipment for steel production in the iron and steel metallurgical industry. Its primary function is to remove impurities such as carbon, silicon, manganese, phosphorus, and sulfur from molten iron. The converter uses oxygen blowing to oxidize these impurities. The oxidation of silicon and manganese raises the temperature of the molten steel, meeting the requirements for subsequent refining and casting. In the later stages of smelting, users add alloying materials to the converter based on the target steel grade's composition, adjusting the alloying element content to achieve the desired properties. The converter's advantage lies in its short smelting cycle, from charging to tapping in approximately 30 minutes. This allows for rapid conversion of molten iron into steel, improving production efficiency and meeting the demands of large-scale production.
[0003] Among them, slag overflow during converter blowing is a more difficult problem in the steelmaking process. In the early stage of blowing (oxidation period), the FeO content in the slag is high and the FeO fluidity is good. At the same time, the oxygen flow rate is large and the gun position is low in the early stage of blowing, which further stirs the molten pool, causing a large amount of gas to be drawn into the slag, prompting foamy slag to form and overflow quickly. After overflowing, the foamy slag will carry a small amount of metal, resulting in a lack of corresponding metal in the finished molten steel. At the same time, the overflowed slag will spread to the surrounding area of the converter, thereby affecting the working environment near the converter.
[0004] In the existing technology, the slag overflow phenomenon is mostly reduced by human observation. When slag overflow occurs in the converter, the converter is manually rotated to the slag discharge position for slag pouring. The converter is prone to multiple slag overflows, so personnel need to perform multiple slag pouring operations during the converter blowing process, which makes the overall converter smelting process too long and increases the overall production time. Summary of the Invention
[0005] The present invention provides a process method for reducing slag overflow during converter blowing. The process involves introducing high-pressure nitrogen and simultaneously blowing the inside of the converter 3-4 minutes after blowing. The high-pressure nitrogen destroys the converter slag layer, reduces the stability and viscosity of the slag layer, promotes its fragmentation and dispersion, and facilitates subsequent slag and iron separation. Simultaneously, the nitrogen forms a large number of tiny bubbles, which generate a stirring effect during the rising process in the slag, causing CO gas in the slag to overflow, reducing the possibility of iron beads being wrapped, and facilitating the separation and sedimentation of the iron beads from the slag, thereby ensuring the purity of molten steel and preventing slag dumping in the converter during blowing.
[0006] To achieve the above object, the present invention provides a process for reducing slag overflow during converter blowing. The process for reducing slag overflow during converter blowing comprises the following steps: S1. Loading the total charge into the converter: Filling the converter with the total charge, the total charge includes scrap steel and molten iron, the scrap steel accounts for 20% to 30% of the total charge, the molten iron accounts for 70% to 80% of the total charge; S2 blowing stage: lower the top oxygen lance position, high-purity oxygen is sprayed into the converter by the top oxygen lance; S3. Nitrogen purging of slag: 3-4 minutes after the converter is blown, slag splashing is observed at the furnace mouth. The converter is kept upright and the top-blown oxygen lance is lowered to 2000-2500 mm from the molten pool surface. At this time, high-pressure nitrogen is blown into the converter through the top-blown oxygen lance and the tuyere at the bottom of the converter. The pressure of the high-pressure nitrogen is adjusted according to the tonnage of the converter. S4. Optimize oxygen supply: Observe the state of the converter furnace slag, reset the top oxygen lance height to the blowing position, the top oxygen lance is converted from high-pressure nitrogen to high-pressure oxygen, and continue the converter blowing; S5. Add auxiliary materials: The auxiliary materials include slag material and converter foam slag inhibitor, personnel according to the reaction of the molten pool in the converter, respectively, small batches of the slag material and the converter foam slag inhibitor; S6. Blowing is completed: steel and slag are tapped from the converter.
[0007] Furthermore, in step S2, the top-blowing oxygen lance is 900 to 1700 mm away from the liquid surface of the molten pool in the converter.
[0008] Furthermore, in step S2, the oxygen supply is optimized, and the oxygen supply includes oxygen pressure and oxygen flow rate. The oxygen pressure is between 0.8 and 1.2 MPa, and the oxygen flow rate is between 23,000 and 25,000 Nm³ / h.
[0009] Furthermore, when the converter tonnage is less than 300 tons, the nitrogen pressure is controlled at 1.0-1.2 MPa; when the converter tonnage is above 300 tons, the nitrogen pressure is controlled at 1.2-1.5 MPa.
[0010] Furthermore, in step S5, auxiliary materials are added in batches to prevent the molten steel in the converter from splashing onto the top-blowing oxygen lance.
[0011] Compared with the prior art, according to an embodiment of the present invention, a process method for reducing slag overflow during converter blowing is provided. After 3-4 minutes of converter blowing, the staff observes the slag droplets in the converter. When the slag droplets splash and overflow, the height of the top-blown oxygen lance is lowered, and high-pressure nitrogen is simultaneously injected into the converter through the top-blown oxygen and the tuyere at the bottom of the converter. The high-pressure nitrogen destroys the slag layer, reduces the stability and viscosity of the slag layer, promotes its crushing and dispersion, and is beneficial to the subsequent slag and iron separation. At the same time, the nitrogen forms a large number of tiny bubbles, which produce a stirring effect during the rising process in the slag, causing the CO gas in the slag to overflow, making the slag composition uniform, reducing the slag-iron interfacial tension, reducing the possibility of iron balls being wrapped, and helping the iron balls to separate and settle from the slag. The nitrogen changes the surface properties of the slag, thereby reducing the surface tension, making the slag droplets of the slag easier to aggregate and grow, accelerating the separation of slag and iron, allowing the iron element to remain in the molten steel, improving the purity of the molten steel, avoiding the return of the molten steel, and reducing the cost of further adding raw materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 The figure is a schematic diagram of the steps of a process for reducing slag overflow during converter blowing according to the present invention. DETAILED DESCRIPTION
[0013] In order to provide a further understanding of the purpose, structure, features, and functions of the present invention, the present invention is described in detail below with reference to the embodiments.
[0014] like Figure 1 As shown, according to the present invention, a process method for reducing converter blowing slag overflow is provided, and the process method for reducing converter blowing slag overflow includes the following steps: S1. Loading the total charge into the converter: Filling the converter with the total charge, the total charge includes scrap steel and molten iron, the scrap steel accounts for 20% to 30% of the total charge, the molten iron accounts for 70% to 80% of the total charge; S2 blowing stage: lower the top oxygen lance position, high-purity oxygen is sprayed into the converter from the top oxygen lance; S3. Nitrogen slag purging: 3-4 minutes after the converter is blown, if slag splashing is observed at the furnace mouth, the converter is kept upright and the top-blown oxygen lance is lowered to 2000-2500 mm from the molten pool level in the converter. At this time, high-pressure nitrogen is blown into the converter through the top-blown oxygen lance and the tuyere at the bottom of the converter. The pressure of the high-pressure nitrogen is adjusted according to the tonnage of the converter; S4. Optimize oxygen supply: personnel observe the reaction in the converter, control the top-blowing oxygen lance to adjust the oxygen flow and pressure, and control the blowing intensity; S5. Add auxiliary materials: The auxiliary materials include slag material and converter foam slag inhibitor, personnel according to the reaction of the molten pool in the converter, respectively, small batches of the slag material and the converter foam slag inhibitor; S6. Blowing is completed: steel and slag are tapped from the converter.
[0015] Preferably, the slag-making material is used to adjust the composition and basicity of the slag, so that the slag has good fluidity and oxidizability, and effectively removes impurities such as phosphorus and sulfur.
[0016] Preferably, the converter foam inhibitor is added when splashing just occurs in the converter. The converter foam inhibitor reacts quickly with the slag, reduces the slag viscosity, eliminates FeO in the foamy slag droplets, slows down the CO reaction, and causes the metal droplets in the foamy slag to settle, which can effectively suppress splashing, prevent slag from sticking to the oxygen chamber, and reduce metal loss from overflowing slag.
[0017] Furthermore, in step S2, the top-blown oxygen lance is 900-1700 mm away from the molten pool liquid surface in the converter, so that the oxygen sprayed from the top-blown oxygen lance quickly contacts with carbon, silicon, manganese and other elements in the molten iron and achieves rapid oxidation.
[0018] Furthermore, in step S2, the oxygen supply is optimized, where the oxygen supply includes oxygen pressure and oxygen flow rate, wherein the oxygen pressure is between 0.8 and 1.2 MPa, and the oxygen flow rate is between 23,000 and 25,000 Nm³ / h.
[0019] Furthermore, during the nitrogen purging slag step, when the converter tonnage is less than 300 tons, the nitrogen pressure is controlled at 1.0 to 1.2 MPa; when the converter tonnage is above 300 tons, the nitrogen pressure is controlled at 1.2 to 1.5 MPa. High-pressure nitrogen is injected into the converter slag layer at high speed. The powerful impact force causes local depressions and disturbances in the slag layer, reducing the stability and viscosity of the slag layer, promoting its fragmentation and dispersion, and facilitating subsequent slag-iron separation. Simultaneously, the nitrogen forms a large number of tiny bubbles, which stir the slag as they rise, causing CO gas to escape from the slag, making the slag composition uniform, reducing the interfacial tension between the slag and iron, and minimizing the possibility of iron beads being trapped, thereby facilitating the separation and sedimentation of the iron beads from the slag. Furthermore, the nitrogen changes the surface properties of the slag, thereby reducing surface tension, making it easier for slag droplets to aggregate and grow, and accelerating slag-iron separation.
[0020] Furthermore, in step S5, auxiliary materials are added in batches to prevent the molten steel in the converter from splashing onto the top-blowing oxygen lance.
[0021] Example 1 In this Example 1, the converter tonnage is 100 tons, the total charge is 122 tons, of which scrap steel is 117 tons and molten iron is 5 tons. In the above Example 1, slag overflow is treated by a process method for reducing slag overflow during converter blowing provided by the present invention, wherein, until splashing occurs in the converter, when nitrogen is blown into the slag, the top-blowing oxygen lance is lowered to 2000 mm from the liquid level of the molten pool in the converter, and the nitrogen pressure is controlled at 1.0 MPa. After the blowing is completed, the slag is poured out, and the composition of the poured slag is tested. The test data is as shown in the following table: Converter tonnage (t) Total charge (t) Scrap steel (t) Molten iron (t) Top blowing oxygen lance position (mm) Nitrogen pressure (Mpa) FeO content (%) 100 122 117 5 2000 1.0 13.51 Among them, Fe content accounts for 13.51% of the total slag weight; Comparative Example In this comparative example 1, the converter tonnage is 100 tons, the total charge is 122 tons, of which scrap steel is 117 tons and molten iron is 5 tons. The comparative example 1 adopts the method of multiple dumping in the prior art to reduce converter slag overflow, and finally the poured slag is tested for composition. The test data are as follows: Converter tonnage (t) Total charge (t) Scrap steel (t) Molten iron (t) FeO content (%) 100 122 117 5 17.37 Among them, Fe content accounts for 17.37% of the total slag weight; Example 2 In this embodiment 2, the converter tonnage is 100 tons, the total charge is 122 tons, of which scrap steel is 117 tons and molten iron is 5 tons. In the above embodiment 1, slag overflow is treated by a process method for reducing slag overflow during converter blowing provided by the present invention, wherein, until splashing occurs in the converter, when nitrogen is blown into the slag, the top-blowing oxygen lance is lowered to 2500 mm from the liquid level of the molten pool in the converter, and the nitrogen pressure is controlled at 1.0 MPa. After the blowing is completed, the slag is poured out, and the composition of the poured slag is tested. The test data is as shown in the following table: Converter tonnage (t) Total charge (t) Scrap steel (t) Molten iron (t) Top blowing oxygen lance position (mm) Nitrogen pressure (Mpa) FeO content (%) 100 122 117 5 2500 1.0 13.4 Among them, Fe content accounts for 13.4% of the total slag weight; In the above-mentioned Example 1, Comparative Example and Example 2, the converter tonnage, total charge weight, scrap steel weight and molten iron weight are all fixed values, while the Comparative Example selects the existing technical solution for slag overflow treatment, and Examples 1 and 2 both select the process method for reducing converter blowing slag overflow proposed by the present invention for slag overflow treatment, and the only variable in Example 1 and Example 2 is: the distance between the top-blown oxygen and the liquid surface of the molten pool in the converter during nitrogen injection. By comparing the FeO content in the slag poured out of the above-mentioned Comparative Example, Example 1 and Example 2, it can be concluded that the FeO content in the slag poured out of Example 1 and Example 2 is less than the FeO content in the slag poured out of the Comparative Example; Therefore, the present invention provides a process method for reducing slag overflow during converter blowing, which can effectively suppress slag dripping and slag overflow that occur in the converter during blowing for 3-4 minutes, thereby avoiding metal loss and improving the purity of molten steel.
[0022] At the same time, after the slag layer is sprayed with high-pressure nitrogen, the formation of overflow slag is destroyed, thereby avoiding the slag pouring process during the converter blowing process, saving blowing time and improving overall work efficiency.
[0023] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" orientations or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention.
[0024] The present invention has been described with reference to the above embodiments. However, the above embodiments are merely exemplary embodiments of the present invention. It should be noted that the disclosed embodiments do not limit the scope of the present invention. On the contrary, modifications and improvements that do not depart from the spirit and scope of the present invention are intended to be protected by the present invention.
Claims
1. A process for reducing slag overflow in converter blowing, characterized in that: The process for reducing converter blowing slag overflow comprises the following steps: S1. Loading the total charge into the converter: Filling the converter with the total charge, the total charge comprises scrap steel and molten iron, the scrap steel accounting for 20% to 30% of the total charge, the molten iron accounting for 70% to 80% of the total charge; S2 blowing stage: lower the top oxygen lance position, high-purity oxygen is sprayed into the converter by the top oxygen lance; S3. Nitrogen slag purging: 3-4 minutes after the converter is blown, if slag splashing is observed at the furnace mouth, the converter is kept upright and the top-blown oxygen lance is lowered to 2000-2500 mm from the molten pool level in the converter. At this time, high-pressure nitrogen is blown into the converter through the top-blown oxygen lance and the tuyere at the bottom of the converter. The pressure of the high-pressure nitrogen is adjusted according to the tonnage of the converter; S4 restore oxygen supply: observe the converter furnace slag state, reset the top oxygen lance height to the blowing position, the top oxygen lance is converted from high-pressure nitrogen to high-pressure oxygen, continue converter blowing; S5. Add auxiliary materials: The auxiliary materials include slag material and converter foam slag inhibitor, personnel according to the reaction in the converter, respectively, small batches of the slag material and the converter foam slag inhibitor; S6. Blowing is completed: steel and slag are tapped from the converter.
2. The process for reducing converter blowing slag overflow according to claim 1, characterized in that: In step S2, the top-blowing oxygen lance is 900 to 1700 mm away from the liquid surface of the molten pool in the converter.
3. The process for reducing converter blowing slag overflow according to claim 1, characterized in that: In step S2, the oxygen supply is optimized, and the oxygen supply includes oxygen pressure and oxygen flow rate. The oxygen pressure is 0.8-1.2 MPa, and the oxygen flow rate is 23000-25000 Nm 3 / h.
4. The process for reducing converter blowing slag overflow according to claim 1, characterized in that: In step S3, if the converter tonnage is less than 300 tons, the nitrogen pressure is controlled at 1.0-1.2 MPa; if the converter tonnage is greater than 300 tons, the nitrogen pressure is controlled at 1.2-1.5 MPa.
5. The process for reducing converter blowing slag overflow according to claim 1, characterized in that: In step S5, auxiliary materials are added in batches to prevent the molten steel in the converter from splashing onto the top-blowing oxygen lance.