A method of controlling oxygen content in a two-high roll cast production of aluminum-containing non-oriented silicon steel

Abstract

This invention belongs to the field of iron and steel smelting technology, and relates to a method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel using twin-roll casting. The chemical composition of the aluminum-containing non-oriented silicon steel, by mass percentage, is: C≤0.0025%, Si: 2.0~2.9%, Mn: 0.45~0.55%, P≤0.03%, S≤0.0025%, Al: 0.65~0.75%, with the remainder being Fe and unavoidable impurities. The process flow adopted in this invention is: KR hot metal pretreatment → converter smelting → LF refining → RH vacuum refining → twin-roll casting. The above-mentioned process and method of this invention solves the problem of excessively high oxygen content in molten steel during the LF process, ensuring that the oxygen content of the molten steel after RH decarburization is controlled within a reasonable range.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel smelting technology, and relates to a method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting. Background Technology

[0002] Non-oriented silicon steel belongs to the ultra-low carbon silicon-ferroalloy steel category. The silicon content of non-oriented silicon steel is typically between 1.5% and 3.0%, or the combined silicon and aluminum content is between 1.8% and 4.0%. The carbon, sulfur, nitrogen, and oxygen content in the steel is minimized to ensure product performance. Non-oriented silicon steel is widely used in electrical equipment such as motors, transformers, and generators. It is an ideal material for manufacturing high-efficiency, high-performance motors and generators, and can also be used to manufacture various transformers, relays, and high-precision instruments.

[0003] Aluminum-containing non-oriented silicon steel adds a certain amount of aluminum to traditional silicon steel, which helps to further reduce the steel's resistivity and increase its magnetic permeability. This allows it to conduct magnetic fields more effectively and reduce core losses. Therefore, aluminum-containing non-oriented silicon steel also has broad application prospects in the field of new energy vehicles.

[0004] The process flow for aluminum-containing non-oriented silicon steel used in twin-roll casting is as follows: KR (Kambara Reactor) hot metal pretreatment - converter smelting - LF (Ladle Furnace) refining - RH (Ruhrstahl & Heraeus) vacuum refining - twin-roll casting. Due to the special nature of the process, after the molten steel is tapped from the converter, it needs to undergo a prolonged energized heating process in the LF refining stage before being hoisted to the RH station for vacuum smelting. High-temperature tapping from the converter reduces the smelting energy consumed by subsequent energized heating, but this also leads to an increase in the oxidizability of the molten steel. Combined with the prolonged energization during the LF refining process, this results in a generally high oxygen content in the molten steel.

[0005] Currently, oxygen content control in silicon steel smelting mainly revolves around converter smelting and RH refining processes. The traditional process is a single RH process, where steel is hoisted from the converter to the RH process for smelting. When the oxygen content of the molten steel at the converter's final stage is too high, a large amount of slag surface deoxidizer is added to the surface of the molten steel during tapping for diffusion deoxidation. On the one hand, the addition of a large amount of slag surface deoxidizer generates a large amount of dust above the ladle, adversely affecting the on-site production environment and the physical and mental health of operators. On the other hand, for twin-roll casting and rolling processes, even with the addition of slag surface deoxidizer after converter tapping, the molten steel still needs to be heated for a long time during transport to the LF process, causing the oxidizing properties of the molten steel to gradually increase again, thus failing to solve the problem of controlling the high oxygen content of the molten steel before the RH process. Furthermore, during RH refining, the molten steel needs sufficient oxygen content to remove carbon to the target value under production conditions and ensure that the oxygen content at the end of decarburization is controlled within a low range.

[0006] Therefore, controlling the oxygen content during the silicon steel smelting process, especially the oxygen content before RH refining, is of great significance for the cleanliness of molten steel and the stability of production. Summary of the Invention

[0007] This invention utilizes the LF-RH dual-process based on the characteristics of twin-roll casting. During the prolonged energization of the LF refining process, the oxidizability of the molten steel gradually increases. If this high oxidizability is not controlled in time, a large amount of deoxidation products will be generated in the subsequent RH deoxidation process. If these products do not float sufficiently, they can easily form inclusions that remain in the molten steel, severely affecting the magnetic properties of silicon steel. Therefore, controlling the oxygen content of the molten steel is crucial. There are three main methods of molten steel deoxidation: precipitation deoxidation, diffusion deoxidation, and vacuum deoxidation. Precipitation deoxidation (containing alloys such as silicon, aluminum, and manganese) easily generates a large amount of deoxidation products, affecting the magnetic properties of silicon steel. Vacuum deoxidation mainly utilizes the carbon-oxygen reaction within the molten steel to generate gaseous carbon oxides, which are easily discharged from the molten steel. However, this cannot be achieved in the LF process; the traditional RH single-process for silicon steel primarily uses this method.

[0008] This invention uses a combination of low-nitrogen carbon raiser and graphite electrode to control oxygen. Through diffusion deoxidation, the oxygen content of molten steel can be controlled without contaminating the molten steel, thereby improving the purity of silicon steel smelting.

[0009] Based on the above, the purpose of this invention is to provide a method for controlling the oxygen content of aluminum-containing non-oriented silicon steel in twin-roll casting production. The specific technical solution adopted by this invention is as follows.

[0010] According to one aspect of the present invention, a method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting is provided. The chemical composition of the non-oriented silicon steel, by mass percentage, is: C≤0.0025%, Si: 2.0~2.9%, Mn: 0.45~0.55%, P≤0.03%, S≤0.0025%, Al: 0.65~0.75%, with the remainder being Fe and unavoidable impurities.

[0011] The method includes the following steps in sequence:

[0012] (1) KR molten iron pretreatment process: Through KR molten iron pretreatment, the S content in the molten iron is controlled at 0.0015~0.0020%;

[0013] (2) Converter smelting process: Lime is added in the 1 / 3 stage of tapping. During the tapping process, the bottom blower of the carbon-free steel ladle is kept open. After tapping, the bottom blower of the ladle is not closed until it is hoisted to the LF refining process.

[0014] (3) LF refining process: The ladle is energized and heated. During the heating period, slag is added in batches. The slag includes lime and fluorite. The single energizing time is controlled to be ≤10min and the cumulative energizing time is controlled to be 13~17min. Then, a low-nitrogen carbonizing agent is added to the ladle. The temperature of the molten steel is controlled to be 1700~1750℃. The LF refining process further includes immersing the electrode in the molten steel for secondary oxygen control according to the oxygen content of the molten steel. When the temperature of the molten steel is controlled to be 1700~1750℃ and the oxygen content is ≤600ppm, the LF refining process is judged to be over. Then, a high-alumina slag surface deoxidizer is added to the surface of the ladle and the ladle is hoisted to the RH vacuum refining position for the RH vacuum refining process.

[0015] (4) RH vacuum refining process: The temperature and oxygen of the molten steel are measured and decarburized. After decarburization, aluminum particles are added for deoxidation and alloying. Then, ultra-low titanium, low aluminum ferrosilicon and metallic manganese are added in sequence. After the molten steel is alloyed, the net circulation is controlled to be ≥8min. Then, high aluminum slag surface deoxidizer is added to the surface of the ladle. The ladle is transferred to the tapping position by the ladle car for wire feeding. After wire feeding, the soft stirring time is controlled to be ≥5min.

[0016] (5) Twin roll casting process: The ladle after the RH vacuum refining process is hoisted to the twin roll casting platform for twin roll casting process.

[0017] According to the method of controlling the oxygen content of aluminum-containing non-oriented silicon steel produced by twin-roll casting according to the present invention, preferably, in the converter smelting process, the amount of lime added at the tapping of the converter is controlled to be 1.5~2.0 kg / t.

[0018] According to the method of controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting according to the present invention, preferably, the bottom blowing of the carbon-free steel ladle is controlled at 600~800NL / min in the converter smelting process.

[0019] According to the method of controlling the oxygen content of aluminum-containing non-oriented silicon steel produced by twin-roll casting according to the present invention, preferably, in the LF refining process, the amount of lime added to the slag is controlled to be 3.0~4.0 kg / t, and the amount of fluorite added is 0.4~0.8 kg / t.

[0020] According to the method for controlling the oxygen content of aluminum-containing non-oriented silicon steel produced by twin-roll casting according to the present invention, preferably, the amount of low-nitrogen carbon raiser added in the LF refining process is 0.5~1.5 kg / t.

[0021] According to the method of controlling the oxygen content of aluminum-containing non-oriented silicon steel produced by twin-roll casting according to the present invention, preferably, in the LF refining process, when the temperature of the molten steel is controlled at 1700~1720℃ and the oxygen content is controlled at 450~600ppm, the LF refining process is judged to be over, and the insertion depth of the graphite electrode into the molten steel is controlled at 4~10cm and the insertion time is controlled at 5~10min.

[0022] According to the method of controlling the oxygen content of aluminum-containing non-oriented silicon steel produced by twin-roll casting according to the present invention, preferably, in the LF refining process, a high-alumina slag surface deoxidizer is added to the ladle surface at a rate of 0.35~0.75 kg / t.

[0023] According to the method of controlling the oxygen content of aluminum-containing non-oriented silicon steel produced by twin-roll casting according to the present invention, preferably, in the RH vacuum refining process, after RH decarburization, aluminum particles are added to the molten steel and controlled to be 8.0~11.0 kg / t.

[0024] According to the method of controlling the oxygen content of aluminum-containing non-oriented silicon steel produced by twin-roll casting according to the present invention, preferably, after adding aluminum particles in the RH vacuum refining process, the molten steel is further circulated for 3 to 5 minutes.

[0025] According to the method of controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting according to the present invention, preferably, in the RH vacuum refining process, the addition of ultra-low titanium and low aluminum ferrosilicon is controlled at 30.0~42.0 kg / t, and the addition of metallic manganese is controlled at 4.8~5.2 kg / t.

[0026] According to the method of controlling the oxygen content of aluminum-containing non-oriented silicon steel produced by twin-roll casting according to the present invention, preferably, after alloying, the molten steel is further purified and circulated for 8-10 minutes in the RH vacuum refining process.

[0027] According to the method of controlling the oxygen content of aluminum-containing non-oriented silicon steel produced by twin-roll casting according to the present invention, preferably, in the RH vacuum refining process, 0.20~0.35 kg / t of high-alumina slag surface deoxidizer is added to the surface of the ladle.

[0028] According to the method of controlling the oxygen content of aluminum-containing non-oriented silicon steel produced by twin-roll casting according to the present invention, preferably, before the RH vacuum refining process, the oxygen content of molten steel is controlled at 400~600ppm, and the FeO+MnO in the molten steel slag is ≤10%; after the RH vacuum refining process, the oxygen content of RH molten steel is controlled at ≤2ppm, and the FeO+MnO in the molten steel slag is ≤3%.

[0029] The method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting according to the present invention preferably includes the following high-alumina slag surface deoxidizer composition added in the LF refining process and the RH vacuum refining process:

[0030] Aluminum: 40-55%; Calcium oxide: 15-25%; Calcium fluoride: 5-10%; Aluminum oxide: 5-15%; Silicon dioxide ≤5%, the rest are unavoidable impurities.

[0031] Beneficial technical effects

[0032] Compared with the prior art, the technical concept and corresponding technical solution of the present invention can achieve at least the following beneficial technical effects:

[0033] 1. This invention uses a twin-roll casting and rolling process to produce aluminum-containing non-oriented silicon steel. The production process is as follows: KR hot metal pretreatment → converter smelting → LF refining → RH vacuum refining → twin-roll casting and rolling. Compared with the traditional smelting process, the process is changed from RH single-run to LF-RH double-run. The oxidation of the molten steel is controlled according to the special characteristics of the double-run process.

[0034] 2. In the LF refining process, a primary deoxidation method using a low-NOx recarburizer and an electrode auxiliary deoxidation method effectively controls the oxygen content of the molten steel. Primary deoxidation with a low-NOx recarburizer helps reduce the oxidizability of the slag, preventing excessively high slag oxidation during prolonged energization, which is detrimental to sulfur control. Simultaneously, the low-NOx recarburizer entering the molten steel effectively reduces its oxygen content. Furthermore, the addition of the low-NOx recarburizer to the ladle promotes the submerged arc effect of the electrodes, reduces heat radiation to the ladle lining, and extends the ladle's lifespan. Further deoxidation using graphite electrode auxiliary deoxidation further controls the oxygen content of the molten steel. Relying solely on low-NOx recarburizer for deoxidation control can easily lead to over-deoxidation or significant carbon increase in the molten steel, resulting in an imbalance of carbon and oxygen content during the RH refining stage.

[0035] 3. Significantly reduces the amount of deoxidizer used on high-alumina slag surfaces, effectively improving the workshop operating environment and the physical and mental health of operators. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0037] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0038] The following are embodiments of the present invention. The described embodiments are only a part of the embodiments of the present invention. All other embodiments that can be obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0039] The present invention will be further illustrated by the following specific embodiments:

[0040] Example 1

[0041] This embodiment provides a method for producing aluminum-containing non-oriented silicon steel. Its composition, by weight percentage, is: C ≤ 0.0025%, Si: 2.1~2.3%, Mn: 0.45~0.55%, P ≤ 0.03%, S ≤ 0.0025%, Al: 0.65~0.75%, with the remainder being Fe and unavoidable impurities. The production process is as follows: KR hot metal pretreatment → converter smelting → LF refining → RH vacuum refining → twin-roll casting and rolling, using a ladle with a nominal capacity of 130±3t.

[0042] KR Hot Metal Pretreatment: Blast furnace hot metal is sent to the KR hot metal pretreatment process for desulfurization. After desulfurization, the sulfur content of the hot metal is 0.0015%.

[0043] Converter smelting: KR-treated molten iron and silicon steel scrap are added to the converter for smelting, using a double-slag operation. After smelting, prepare for tapping. Before tapping, ensure unobstructed bottom blowing in the carbon-free steel ladle. No alloys are added during tapping. When the molten steel reaches about 1 / 3 of the ladle's capacity, add 200 kg of lime. The bottom blowing in the carbon-free steel ladle is controlled at approximately 750 NL / min. Slag addition is prohibited during tapping. After tapping, maintain bottom blowing in the ladle for 2 minutes while waiting for the overhead crane to be positioned. After positioning, the steel is hoisted to the LF refining process.

[0044] LF refining process: After the molten steel arrives at the station, it is heated by electricity. During the LF heating stage, lime, fluorite, and other slag materials are added in batches, with a cumulative total of 440 kg of lime and 60 kg of fluorite. Low-nitrogen carbon raiser is added in the later stages of LF smelting. After a cumulative 13 minutes of electricity application, when the oxygen content of the molten steel reaches 650 ppm, 80 kg of low-nitrogen carbon raiser is added, and smelting continues.

[0045] The molten steel temperature was measured at 1715℃. The use of low-nitrogen carbon raiser was discontinued. A graphite electrode was inserted 5cm into the molten pool and held for 6 minutes. Finally, electricity was applied for another 0.5 minutes to end the smelting process, and the temperature was measured at 1714℃, with an oxygen concentration of 550ppm. After LF refining, 80kg of high-alumina slag surface deoxidizer was added to the ladle. One minute later, a crane transported the ladle to the RH vacuum refining process.

[0046] RH Vacuum Refining Process: Upon arrival of molten steel, the ladle is immediately lifted to the processing position, and a vacuum is immediately created by pumping. After evacuation for 14-15 minutes, an oxygen level of 380 ppm is determined. After decarburization, 1140 kg of aluminum granules are added to the molten steel. After a 3-minute wait, 4130 kg of ultra-low titanium, low-aluminum ferrosilicon and 660 kg of metallic manganese are added. After alloying, the steel undergoes a net circulation for 8 minutes. Following the net circulation, the vacuum is broken and the oxygen level is determined to 1.5 ppm. 30 kg of high-alumina slag surface deoxidizer is then added to the ladle. After breaking the vacuum, the ladle is transferred to the tapping position and fed with calcium wire. Soft stirring is performed for 7 minutes. After soft stirring, the ladle is hoisted to the twin-roll casting platform for protective casting.

[0047] Example 2

[0048] This embodiment provides a method for producing aluminum-containing non-oriented silicon steel. Its composition, by weight percentage, is: C ≤ 0.0025%, Si: 2.4~2.6%, Mn: 0.45~0.55%, P ≤ 0.03%, S ≤ 0.0025%, Al: 0.65~0.75%, with the remainder being Fe and unavoidable impurities. The production process is as follows: KR hot metal pretreatment → converter smelting → LF refining → RH vacuum refining → twin-roll casting and rolling, using a ladle with a nominal capacity of 130±3t.

[0049] KR Hot Metal Pretreatment: Blast furnace hot metal is sent to the KR hot metal pretreatment process for desulfurization. After desulfurization, the sulfur content of the hot metal is 0.0018%.

[0050] Converter smelting: KR-treated molten iron and silicon steel scrap are added to the converter for smelting, using a double-slag operation. After smelting, prepare for tapping. Before tapping, ensure unobstructed bottom blowing in the carbon-free steel ladle. No alloys are added during tapping. When the molten steel reaches about 1 / 3 of the ladle's capacity, add 220 kg of lime. The bottom blowing in the carbon-free steel ladle is controlled at approximately 700 NL / min. Slag addition is prohibited during tapping. After tapping, maintain bottom blowing in the ladle for 2 minutes while waiting for the overhead crane to be positioned. After positioning, the steel is hoisted to the LF refining process.

[0051] LF refining process: After the molten steel arrives at the station, it is heated by electricity. During the LF heating stage, lime, fluorite, and other slag materials are added in batches, with a total of 480 kg of lime and 80 kg of fluorite. Low-nitrogen carbon raiser is added in the later stages of LF smelting. After a total of 15 minutes of electricity application, when the oxygen content of the molten steel reaches 680 ppm, 100 kg of low-nitrogen carbon raiser is added, and smelting continues.

[0052] The molten steel temperature was measured at 1720℃. The use of low-nitrogen carbon raiser was discontinued. A graphite electrode was inserted 6cm into the molten pool and held for 7 minutes. Finally, electricity was applied for another 0.5 minutes to end the smelting process. The temperature was measured at 1715℃, and the oxygen concentration was 560ppm. After LF refining, 90kg of high-alumina slag surface deoxidizer was added to the ladle. One minute later, a crane transported the ladle to the RH vacuum refining process.

[0053] RH Vacuum Refining Process: Upon arrival of molten steel, the ladle is immediately lifted to the processing position, and a vacuum is immediately created by pumping. After evacuation for 14-15 minutes, an oxygen level of 400 ppm is determined. After decarburization, 1200 kg of aluminum granules are added to the molten steel. After a 4-minute wait, 4700 kg of ultra-low titanium, low-aluminum ferrosilicon and 664 kg of metallic manganese are added. After alloying, the steel undergoes a net circulation for 8 minutes. Following this circulation, the vacuum is broken and the oxygen level is determined to 1.5 ppm. 30 kg of high-alumina slag surface deoxidizer is then added to the ladle. After breaking the vacuum, the ladle is transferred to the tapping position and fed with calcium wire. Soft stirring is performed for 7 minutes. After soft stirring, the ladle is hoisted to the twin-roll casting platform for protective casting.

[0054] Example 3

[0055] This embodiment provides a method for producing aluminum-containing non-oriented silicon steel. Its composition, by weight percentage, is: C ≤ 0.0025%, Si: 2.7~2.9%, Mn: 0.45~0.55%, P ≤ 0.03%, S ≤ 0.0025%, Al: 0.65~0.75%, with the remainder being Fe and unavoidable impurities. The production process is as follows: KR hot metal pretreatment → converter smelting → LF refining → RH vacuum refining → twin-roll casting and rolling, using a ladle with a nominal capacity of 130±3t.

[0056] KR Hot Metal Pretreatment: Blast furnace hot metal is sent to the KR hot metal pretreatment process for desulfurization. After desulfurization, the sulfur content of the hot metal is 0.0020%.

[0057] Converter smelting: KR-treated molten iron and silicon steel scrap are added to the converter for smelting, using a double-slag operation. After smelting, prepare for tapping. Before tapping, ensure unobstructed bottom blowing in the carbon-free steel ladle. No alloys are added during tapping. When the molten steel reaches about 1 / 3 of the ladle's capacity, add 240 kg of lime. The bottom blowing in the carbon-free steel ladle is controlled at approximately 800 NL / min. Slag addition is prohibited during tapping. After tapping, maintain bottom blowing in the ladle for 2.5 minutes while waiting for the overhead crane to be positioned. After positioning, the steel is hoisted to the LF refining process.

[0058] LF refining process: After the molten steel arrives at the station, it is heated by electricity. During the LF heating stage, lime, fluorite, and other slag materials are added in batches, with a cumulative amount of 500 kg of lime and 90 kg of fluorite. Low-nitrogen carbon raiser is added in the later stages of LF smelting. After a cumulative 17 minutes of electricity application, when the oxygen content of the molten steel reaches 700 ppm, 120 kg of low-nitrogen carbon raiser is added, and smelting continues.

[0059] The molten steel temperature was measured at 1725℃. The use of low-nitrogen carbon raiser was discontinued. A graphite electrode was inserted 9cm into the molten pool and held for 10 minutes. Finally, electricity was applied for another 0.5 minutes to end the smelting process, and the temperature was measured at 1718℃, with an oxygen concentration of 570ppm. After LF refining, 80kg of high-alumina slag surface deoxidizer was added to the ladle. One minute later, a crane transported the ladle to the RH vacuum refining process.

[0060] RH Vacuum Refining Process: Upon arrival of molten steel, the ladle is immediately lifted to the processing position, and the pump is immediately started to create a vacuum. After evacuation for 14-15 minutes, the oxygen content is fixed at 440 ppm. After decarburization, 1250 kg of aluminum granules are added to the molten steel. After waiting for 4 minutes, 5260 kg of ultra-low titanium and low-aluminum ferrosilicon and 650 kg of metallic manganese are added. After alloying, the steel is circulated net for 10 minutes. After net circulation, the vacuum is broken and the oxygen content is fixed at 2 ppm. 40 kg of high-alumina slag surface deoxidizer is added to the ladle. After breaking the vacuum, the ladle is transferred to the tapping position and fed with calcium wire. Soft stirring is performed for 8 minutes. After soft stirring, the ladle is hoisted to the twin-roll casting platform for protective casting.

[0061] The above description is only a specific embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel using twin-roll casting and rolling, wherein the chemical composition of the non-oriented silicon steel, expressed as a percentage by mass, is: C≤0.0025%, Si: 2.0~2.9%, Mn: 0.45~0.55%, P≤0.03%, S≤0.0025%, Al: 0.65~0.75%, The remainder consists of Fe and unavoidable impurities; The method includes the following steps in sequence: (1) KR molten iron pretreatment process: Through KR molten iron pretreatment, the S content in the molten iron is controlled at 0.0015~0.0020%; (2) Converter smelting process: Lime is added in the 1 / 3 stage of tapping. During the tapping process, the bottom blower of the carbon-free steel ladle is kept open. After tapping, the bottom blower of the ladle is not closed until it is hoisted to the LF refining process. (3) LF refining process: The ladle is energized and heated. During the heating period, slag is added in batches. The slag includes lime and fluorite. The single energizing time is controlled to be ≤10min and the cumulative energizing time is controlled to be 13~17min. Then, a low-nitrogen carbonizing agent is added to the ladle. The temperature of the molten steel is controlled to be 1700~1750℃. The LF refining process further includes immersing the electrode in the molten steel for secondary oxygen control according to the oxygen content of the molten steel. When the temperature of the molten steel is controlled to be 1700~1750℃ and the oxygen content is ≤600ppm, the LF refining process is judged to be over. Then, a high-alumina slag surface deoxidizer is added to the surface of the ladle and the ladle is hoisted to the RH vacuum refining position for the RH vacuum refining process. (4) RH vacuum refining process: The temperature and oxygen of the molten steel are measured and decarburized. Aluminum particles are added for deoxidation and alloying. Then, ultra-low titanium, low aluminum ferrosilicon and metallic manganese are added in sequence. The net circulation of the molten steel after alloying is controlled to be ≥8min. Then, high aluminum slag surface deoxidizer is added to the surface of the ladle. The ladle is transferred to the tapping position by the ladle car for wire feeding. The soft stirring time after wire feeding is controlled to be ≥5min. (5) Twin roll casting process: The ladle after the RH vacuum refining process is hoisted to the twin roll casting platform for twin roll casting process.

2. The method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting and rolling according to claim 1, characterized in that: In the converter smelting process, the amount of lime added during converter tapping is controlled at 1.5~2.0 kg / t.

3. The method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting and rolling according to claim 1, characterized in that: In the converter smelting process, the bottom blowing of the carbon-free steel ladle is controlled at 600~800NL / min.

4. The method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting and rolling according to claim 1, characterized in that: In the LF refining process, the amount of lime added to the slag is controlled at 3.0~4.0 kg / t, and the amount of fluorite added is 0.4~0.8 kg / t.

5. The method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting and rolling according to claim 1, characterized in that: In the LF refining process, the amount of low-nitrogen carbon raiser added is 0.5~1.5 kg / t.

6. The method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting and rolling according to claim 1, characterized in that: In the LF refining process, when the temperature of the molten steel is controlled at 1700~1720℃ and the oxygen content is controlled at 450~600ppm, the LF refining process is considered to be over. The insertion depth of the graphite electrode into the molten steel is controlled at 4~10cm and the insertion time is controlled at 5~10min.

7. The method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting and rolling according to claim 1, characterized in that: In the LF refining process, the amount of high-alumina slag surface deoxidizer added to the ladle surface during LF tapping is controlled at 0.35~0.75 kg / t.

8. The method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting and rolling according to claim 1, characterized in that: In the RH vacuum refining process, after RH decarburization, aluminum particles are added to the molten steel at a controlled rate of 8.0~11.0 kg / t.

9. The method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting and rolling according to claim 8, characterized in that: In the RH vacuum refining process, after adding aluminum granules, the molten steel is further circulated for 3-5 minutes.

10. The method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting and rolling according to claim 9, characterized in that: In the RH vacuum refining process, the addition of ultra-low titanium and low aluminum ferrosilicon is controlled at 30.0~42.0 kg / t, and the addition of metallic manganese is controlled at 4.8~5.2 kg / t.

11. The method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting and rolling according to claim 10, characterized in that: In the RH vacuum refining process, after alloying, the molten steel is further purified and circulated for 8-10 minutes.

12. The method for controlling the oxygen content in the production of aluminum-containing non-oriented silicon steel by twin-roll casting and rolling according to claim 1, characterized in that: In the RH vacuum refining process, 0.20~0.35 kg / t of high-alumina slag surface deoxidizer is added to the ladle surface.

13. The method for controlling the oxygen content in twin-roll casting and rolling of aluminum-containing non-oriented silicon steel according to any one of claims 1 to 12, characterized in that: Before the RH vacuum refining process, the oxygen content of the molten steel is controlled at 400~600ppm, and the FeO+MnO in the molten steel slag is ≤10%. After the RH vacuum refining process, the oxygen content of RH molten steel is controlled to ≤2ppm, and the FeO+MnO in the molten steel slag is ≤3%.

14. The method for controlling the oxygen content in twin-roll casting and rolling of aluminum-containing non-oriented silicon steel according to any one of claims 1 to 12, characterized in that: The components of the high-alumina slag surface deoxidizer added in the LF refining process and the RH vacuum refining process are as follows: Aluminum: 40-55%; Calcium oxide: 15-25%; Calcium fluoride: 5-10%; Aluminum oxide: 5-15%; Silicon dioxide ≤5%, the rest are unavoidable impurities.