A method for rapid slagging of lf refining

Abstract

The present application belongs to converter steelmaking technical field, provide a kind of LF refining quick slag melting method, the present application is injected with pre-melting agent along with molten steel in the process of converter tapping, the composition of pre-melting agent is according to mass percentage respectively: calcium oxide 60-70%, lithium oxide 4-7%, silicon dioxide 3-6%, calcium fluoride 5-10%, magnesium oxide 4-8%, di-aluminum oxide 10-15%, by adding the above pre-melting agent in the process of tapping, while improving the basicity of slag, effectively reduce the melting point of slag, promote the rapid melting of slag, shorten the LF refining station furnace slag melting time, and inhibit the occurrence of phosphorus, reduce the LF refining smelting time, provide good guarantee for rolling quality.The application of the present application can provide a reliable smelting method for improving production efficiency for operators, which can effectively reduce production cost, while ensuring the purity of molten steel.

Description

Technical Field

[0001] This invention belongs to the field of converter steelmaking technology, and particularly relates to a rapid slag melting method for LF refining. Background Technology

[0002] With the continuous development of steel enterprises, the market demands increasingly higher levels of steel cleanliness, especially minimizing harmful elements such as phosphorus and inclusions. In the steelmaking process, the slag entering the ladle from the converter contains a large amount of phosphorus, a harmful element. If left untreated, this can lead to high phosphorus levels in the molten steel, forcing re-evaluation or scrapping. Effective phosphorus removal can be achieved by either skimming the slag, which is time-consuming, labor-intensive, and requires re-slag formation, increasing costs; or by increasing the slag's basicity and oxidizing properties, which increases its viscosity and melting point, leading to increased deoxidation and alloying dosages. Furthermore, highly oxidizing slag can increase the oxygen content of the molten steel, thus reducing its cleanliness. Therefore, for high-quality steel, the goal is to minimize phosphorus levels in the molten steel after tapping from the converter, reduce costs as much as possible, and avoid a decrease in steel cleanliness.

[0003] Chinese patent document CN101058838A (CN200710099032.1) discloses a method for pre-refining molten steel during the tapping process. In this method, aluminum and refining flux are added to the molten steel in the ladle. The strong stirring effect created by the molten steel "rushing" into the ladle during tapping desulfurizes, deoxidizes, and transforms and removes inclusions, achieving good desulfurization, deoxidation, and inclusion control. However, the pre-flux used in this patent has a calcium oxide content of 85-95% and a calcium fluoride content of 5-15%. The excessively high calcium oxide content results in a prolonged slag formation time for refining, which is detrimental to the continuous control of inclusions. Furthermore, the aforementioned pre-refining process cannot guarantee effective control of phosphorus content. Summary of the Invention

[0004] To address the above problems, this invention provides a rapid slag refining method for LF (Leakage Refining). Based on existing conditions, a pre-melting agent is added during the steel tapping process. The composition of the pre-melting agent not only ensures the fluidity and basicity of the slag but also reduces phosphorus return in the molten steel, ensuring the cleanliness of the molten steel and thus providing raw material assurance for the quality of rolled products.

[0005] The technical problem to be solved by this invention is achieved by the following technical solution: a rapid slag refining method for LF, comprising the following steps:

[0006] S1. Pre-melting agent is added during the tapping process of the converter along with the molten steel flow;

[0007] The components of the pre-melting flux, in terms of mass percentage, are: calcium oxide 60-70%, lithium oxide 4-7%, silicon dioxide 3-6%, calcium fluoride 5-10%, magnesium oxide 4-8%, and aluminum oxide 10-15%.

[0008] When two-thirds of the total volume of molten steel has flowed out, add 500-800 kg of pre-melting agent along with the molten steel. When adding the agent, control the addition speed to be 30-50 kg / s.

[0009] S2. When slag is detected in the converter, close the converter tapping port;

[0010] S3. Send the ladle to LF refining, measure the oxygen content of the molten steel, and then open the bottom blowing argon valve. Turn the argon gas to 800-1200L / min and stir for 30-60 seconds. Under the stirring of the gas, ensure that the molten steel churns to a height of 20-50cm. During the stirring process, add 10-50kg of aluminum granules to the slag. After stirring is complete, add 50-150kg of lime and turn on the power to adjust the slag and temperature.

[0011] The technical solution of the present invention also includes: in step S1, no pre-melting agent is added 30 seconds before the end of steel tapping, so as not to affect the accuracy of the slag detection equipment.

[0012] The technical solution of the present invention also includes: in step S3, if the oxygen content of the molten steel is >50ppm, then 30-50kg of aluminum granules are added;

[0013] If the oxygen content in the molten steel is less than 50 ppm and the oxygen content is less than 20 ppm, then add 10-30 kg of aluminum granules.

[0014] If the oxygen content is <20ppm, add 10kg of aluminum granules.

[0015] The technical solution of the present invention also includes: in step S1, the pre-melting agent is pressed into... It is used after being spherical. This is achieved by pressing the pre-melted flux into... The spherical shape makes it easy to add and avoids dust pollution.

[0016] The technical solution of the present invention also includes: in step S1, the pre-melting agent addition point must always be aligned with the pouring point position of the molten steel being poured into the ladle to ensure that the pre-melting agent melts quickly under the impact of the molten steel flow.

[0017] The technical solution of the present invention also includes: if the pre-melting agent does not melt well, that is, agglomerates appear around the impact zone of molten steel, when the diameter of the agglomerates is <30cm, the addition speed of the pre-melting agent is adjusted to 15-25kg / s, and the ladle is adjusted to ensure that the molten steel flow impacts the agglomerate position and promotes its rapid and complete melting.

[0018] When the agglomeration diameter is less than 50 cm and the agglomeration diameter is less than 30 cm, stop adding pre-melting agent, adjust the ladle so that the molten steel flow impacts the agglomeration position, and ensure that the agglomeration is completely melted before adding pre-melting agent at the initial addition rate.

[0019] When the diameter of the agglomeration is less than 50cm, stop adding pre-melting flux, adjust the ladle to ensure that the molten steel flow impacts the agglomeration location, and continue until the steel tapping is completed.

[0020] The inventive concept of this invention: Calcium oxide is an essential material for slag formation, dephosphorization, and desulfurization in metallurgy, and is one of the main components of various slag systems. Generally speaking, the basicity of slag is achieved by adjusting the ratio of calcium oxide to silicon dioxide, i.e., basicity = calcium oxide / silicon dioxide. The suitable basicity range is typically 2.5-8. For aluminum-containing steel, the basicity is usually higher (5-8), while for non-aluminum-containing steel, the basicity is usually lower (2.5-3). For example, if the slag contains 55% calcium oxide and 18% silicon dioxide, the basicity is 3.05. It is evident that the higher the calcium oxide content and the lower the silicon dioxide content, the higher the basicity, and vice versa.

[0021] However, higher slag basicity is not always better; in fact, excessively high basicity is detrimental. Higher basicity results in a more viscous slag, reducing its fluidity and hindering desulfurization, dephosphorization, and inclusion adsorption. Conversely, excessively low basicity leads to a thinner slag, which, while improving fluidity, also impedes desulfurization, dephosphorization, and inclusion adsorption, and negatively impacts the stability of the electric arc during LF refining. Therefore, slag basicity must be controlled within a suitable range, neither too high nor too low. Similarly, controlling slag basicity requires adjusting the content of calcium oxide and silica separately.

[0022] Furthermore, the earlier the slag is refined, the better. Good slag can promote dephosphorization, desulfurization, adsorption of inclusions, and stabilize the electric arc for rapid temperature increase. These factors all contribute to better steel quality and purity, allowing the steel to reach the required temperature more quickly, thus shortening refining time and providing high-quality steel. Therefore, for those skilled in the art, ensuring that LF refining produces steel with high crystallinity and few inclusions in a short time is a constantly pursued goal.

[0023] Generally, when there are no other sources, the amount of silica in the slag (mainly brought in from the converter) is relatively stable. Basicity adjustment is primarily achieved by adjusting the amount of calcium oxide; when the total calcium oxide content is too low, calcium oxide needs to be added. Therefore, setting the calcium oxide content in the pre-melting flux at 60-70%, combined with the calculated addition amount, provides sufficient total calcium oxide for most heats. If insufficient, only a small increase is needed to achieve the appropriate basicity, facilitating LF refining operations.

[0024] Lithium oxide exhibits excellent dephosphorization and desulfurization effects, while the resulting slag has a low melting point, thus facilitating slag formation. Adding 4-7% lithium oxide, which belongs to the same group as calcium oxide, results in a stronger basicity than calcium oxide, and the metal cations are more effective against O. 2- The attraction is small, making the slag O 2- Increased activity promotes the reaction of P2O5 and O in the slag. 2- Combined and converted into PO 3- 4. It exists stably. In addition, lithium oxide can form low-melting-point compounds with calcium oxide, silicon dioxide and calcium silicate, which are much lower than the melting point of 2CaO·SiO2. This reduces the melting point of the slag, increases the basicity of the slag, and avoids the increase in melting point caused by excessive CaO.

[0025] When calculating basicity, lithium oxide needs to be taken into account, i.e.: Basicity = (Calcium oxide + Lithium oxide) / Silicon dioxide. Therefore, it helps to increase basicity. According to the dephosphorization reaction, dephosphorization requires high slag basicity and oxygen potential. After adding lithium oxide, the slag basicity and oxygen potential are increased, the kinetic conditions for dephosphorization are improved, and dephosphorization is promoted.

[0026] Adding lithium oxide increases the basicity of the slag and also promotes the desulfurization of calcium oxide. Sulfur exists in the form of FeS. When there is enough CaO in the slag, sulfur can also be removed. The reaction is as follows: FeS + CaO → CaS + FeO. The generated CaS does not dissolve in the molten steel but forms slag that floats on the surface of the molten steel.

[0027] Silica has a certain fluxing effect; it is an important component of basicity. Typically, the silica in LF refining slag is produced after converter smelting, flowing into the ladle and entering the top slag during tapping. Adding 3-6% here serves the same purpose: to increase the slag's fluxing effect, allowing it to melt more quickly. However, excessive silica should be avoided, as it will significantly reduce the slag's basicity, resulting in a severely thin slag.

[0028] Calcium fluoride can significantly reduce slag viscosity and improve slag fluidity. It is a recognized slag-melting flux in metallurgical enterprises; adding 5-10% here aims to promote the melting of calcium oxide. However, due to its high price and the environmental pollution caused by fluorides, it should not be added in excess. Furthermore, adding too much calcium fluoride can also result in excessively thin slag.

[0029] Magnesium oxide (MgO) has a certain desulfurization capacity and also protects the furnace lining bricks. MgO can help adjust the slag, forming a CaO-MgO-Al2O3 ternary slag system, thereby promoting the desulfurization effect. Simultaneously, MgO has a high melting point, which, when added, can reduce the erosion of the furnace lining bricks by the slag (converters and ladles require refractory materials such as furnace lining bricks inside their steel shells to isolate them from the erosion of high-temperature molten steel and slag). However, excessive MgO can make the slag viscous and difficult to melt; therefore, an addition of 4-8% is recommended.

[0030] Aluminum oxide (ANO) can reduce slag viscosity, promote steel slag reaction, and facilitate desulfurization. Aluminum oxide is an important component of slag. Typically, CaO, SiO2, and Al2O3 can form a ternary slag system, as can CaO, MgO, and Al2O3. These slag systems are characterized by low oxygen potential, low melting point, low viscosity, and easy absorption of inclusions generated during deoxidation. This promotes steel slag reaction, facilitates desulfurization, and provides favorable conditions for other chemical reactions. The 10-15% ratio mentioned here takes into account the characteristics of the ternary slag system and the proportions of each element. Too little ANO is not conducive to forming the optimal slag with the above characteristics, while too much will make the slag too thin, requiring blending and hindering the adsorption of inclusions.

[0031] In this invention, after the pre-melting agent is added, it gradually melts with the stirring of molten steel. Due to its low density, it is typically 2.4-3.0 g / cm³. 3 It is far less than the density of molten steel, which is 7.8 g / cm³. 3 The slag floats to the surface of the molten steel and forms slag. Together with the slag that enters the converter in the later stage of steelmaking, it forms a complex compound. During the transport to the LF refining process, the slag gradually merges and changes, eventually forming slag with LF refining characteristics (good refining slag has a low melting point, suitable viscosity, good fluidity, good adsorption of inclusions, good desulfurization ability, good foaming effect, and good heating and heat preservation effect).

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] This invention involves adding a pre-melting agent along with the molten steel during the converter tapping process. The composition of the pre-melting agent, by mass percentage, is as follows: calcium oxide 60-70%, lithium oxide 4-7%, silicon dioxide 3-6%, calcium fluoride 5-10%, magnesium oxide 4-8%, and aluminum oxide 10-15%. By adding the above-mentioned pre-melting agent during the tapping process, the slag basicity is increased, the slag melting point is effectively reduced, the slag melting is promoted, the slag melting time at the LF refining station is shortened, and the occurrence of phosphorus reversion is inhibited. This reduces the LF refining smelting time and provides a good guarantee for the quality of rolled products.

[0034] This invention is simple to operate, easy to execute, and yields good results. The method of this invention can be applied in any steel plant producing similar steel grades (all aluminum-containing steels), and has the advantages of wide application and high promotional value. Detailed Implementation

[0035] The embodiments of the present invention will be described in further detail below with reference to examples. These examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0036] Example 1

[0037] Taking the 120-ton top-and-bottom combined blowing converter of Shandong Iron and Steel Co., Ltd. as an example, the specific implementation of the present invention is described in detail below.

[0038] This invention proposes a rapid slag refining method for LF (Left-Fluid Refining), comprising the following steps:

[0039] S1. After the converter smelting is completed and the steel composition meets the tapping requirements after testing, the converter is rotated, and the molten steel flows out from the tapping port into the ladle. During the tapping process, pre-melting flux is added along with the molten steel flow. The pre-melting flux is added in advance to the silo behind the furnace for later use.

[0040] The pre-melting flux, by weight percentage, consists of: 65% calcium oxide, 6% lithium oxide, 4% silicon dioxide, 8% calcium fluoride, 5% magnesium oxide, and 12% aluminum oxide, and is produced by pressing. Use after shaping into a spherical shape.

[0041] When two-thirds of the molten steel has flowed out, add 500-800 kg of pre-melting agent along with the molten steel. When adding, control the addition speed to 30-50 kg / s. The addition point should always be aligned with the pouring point of the molten steel in the ladle to ensure that the pre-melting agent melts quickly under the impact of the molten steel.

[0042] If the pre-melting flux does not melt well (i.e., agglomerates appear around the molten steel impact zone), when the agglomerate diameter is <30cm, adjust the addition speed to 15-25kg / s, adjust the ladle to ensure that the molten steel flow impacts the agglomerate location, and promote its rapid and complete melting.

[0043] When the agglomeration diameter is less than 50 cm and the agglomeration diameter is less than 30 cm, stop adding pre-melting agent, adjust the ladle so that the molten steel flow impacts the agglomeration position, and ensure that the agglomeration is completely melted before adding pre-melting agent at the initial addition rate.

[0044] When the diameter of the agglomeration is less than 50cm, stop adding pre-melting flux, adjust the ladle to ensure that the molten steel flow impacts the agglomeration location, and continue until the steel tapping is completed.

[0045] In any case, no pre-melting agent should be added 30 seconds before the end of tapping to avoid affecting the accuracy of the slag detection equipment.

[0046] S2. When slag discharge is detected, the control valve should be closed in time, and slag discharge from the tapping port will cease.

[0047] S3. The ladle, filled with molten steel, is transported by overhead crane to the designated LF refining station for further processing. After entering the LF refining station, the oxygen content of the molten steel is measured. The bottom-blowing argon gas valve is then opened, and the argon gas flow rate is increased to 800-1200 L / min (ensuring the molten steel churns to a height of 20-50 cm under gas agitation). The mixture is stirred for 30-60 seconds. During stirring, 10-50 kg of 99% Al granules are added to the slag. (If the oxygen content of the molten steel is >50 ppm, add 30-50 kg of aluminum granules; if the oxygen content is 20 ppm < 50 ppm, add 10-30 kg of aluminum granules; if the oxygen content is <20 ppm, add 10 kg of aluminum granules.) Adding aluminum granules reduces the oxidizing properties of the slag. After stirring, 50-150 kg of lime is added, and the temperature of the slag and molten steel is adjusted by applying electricity.

[0048] Comparative Example 1

[0049] The converter uses a traditional tapping method to produce the same steel grade as in Comparative Example 1. Taking the 120-ton converter at Shandong Iron and Steel Group's section steelmaking plant as an example, the specific operating steps are as follows:

[0050] Step 1) Add the pre-melted slag to the silo behind the furnace for later use.

[0051] Pre-melted slag is one of the slag-forming materials widely used in metallurgical enterprises. It is usually added to steel ladles to improve the melting point and fluidity of slag. Its effective components, in terms of mass percentage, are: Al2O3: 20-30%, SiO2: 20-30%, MgO: 5-10%, CaO: 7-10%, and calcium fluoride: 20-30%.

[0052] Step 2) After the converter smelting is completed, the composition of the molten steel meets the requirements for tapping.

[0053] Step 3) Rotate the converter to allow molten steel to flow from the tapping port into the ladle.

[0054] Step 4) When the molten steel has flowed out to three-quarters of its total volume, add 500-800 kg of pre-melted slag along with the molten steel. The addition point should always be aligned with the pouring point of the molten steel being poured into the ladle.

[0055] Step 5) When slag discharge is detected, close the control valve in time, and slag will no longer be discharged from the tapping port.

[0056] Step 6) The ladle, filled with molten steel, is hoisted by an overhead crane and transported to the designated LF refining station for further processing.

[0057] Step 7) After the ladle containing molten steel enters the LF refining process, the oxygen content of the molten steel is measured. Then, the bottom-blowing argon valve is opened, and the argon flow rate is increased to 1200-1500 L / min (ensuring the molten steel churns to a height exceeding 50 cm under gas stirring). Stir for 1 minute. During stirring, 50 kg of aluminum granules (99% Al) is added to the slag to reduce its oxidizing properties. Lime (500-600 kg) and fluorite (0-100 kg) are added in three batches to aid slag formation. To lower the slag melting point and improve its fluidity, the pre-melted slag has a low CaO content. Although it melts quickly, its low basicity and thin slag make it unsuitable for arc stabilization and temperature rise, and it cannot effectively adsorb inclusions. Therefore, a large amount of lime must be added to adjust the slag. To promote lime melting, fluorite is added. After stirring, the slag and temperature are adjusted by energizing, which increases the LF refining time.

[0058] Compared to Example 1, the calcium oxide content in Comparative Example 1 is only 7-10%, which is significantly insufficient considering the amount added. The difference in calcium oxide content is substantial, requiring additional addition of 500-600 kg in 2-3 batches. Each addition of calcium oxide necessitates electrolytic slag treatment, with one batch only allowed to be added after the previous one has been slag-treated. This increases the refining and slag-treatment time, delaying slag formation and negatively impacting desulfurization, dephosphorization, inclusion adsorption, and rapid temperature rise. To produce high-quality molten steel, more processing time is required, increasing power consumption and refining time, which adversely affects cost reduction and cycle matching.

[0059] The effects of Example 1 and Comparative Example 1 are compared, and the corresponding results are shown in Table 1:

[0060] Table 1

[0061]

[0062] Generally, the lower the phosphorus content in molten steel, the better. However, under the conditions of steelmaking converters, the dephosphorization rate is typically 85-95% (further increasing the dephosphorization rate would significantly increase the difficulty and cost). This means that when the initial phosphorus content in the molten iron is 0.150%, the final phosphorus content in the converter is usually around 0.015%. After refining, the phosphorus content recovers to around 0.016% (sometimes a large amount of recovered phosphorus leads to excessive phosphorus content and rejection). Many steel grades require the finished product phosphorus content not to exceed 0.015%. Therefore, the goal is to minimize or eliminate phosphorus recovery in the molten steel produced by the converter (phosphorus is a harmful element in steel, causing problems such as phosphorus embrittlement and cracking; the higher the phosphorus content, the more severe the problems). However, after the converter smelting is complete, the phosphorus content in the molten steel gradually increases during the refining process, which is commonly referred to as "phosphorus recovery." Technicians have researched many methods to reduce phosphorus recovery during refining, but good methods have drawbacks (increased cost, increased time, etc.). Based on the data in Table 1, it can be seen that the method of this application significantly reduces the amount of phosphorus reversion in the LF refining stage compared with Comparative Example 1.

[0063] Furthermore, as mentioned earlier, refining has specific smelting time requirements. Within a limited timeframe, the earlier the slag formation and the longer it is maintained, the better. Once good slag is formed, it can desulfurize, prevent phosphorus reversion, and adsorb more inclusions, including Al2O3. During the refining process, argon gas is continuously blown into the bottom of the ladle. Under the stirring effect of the argon gas, inclusions collide and grow into large particles that circulate within the molten steel. If the adsorption effect of the refining slag is poor, Al2O3 will continuously circulate within the molten steel until good slag is formed, at which point it will gradually float to the surface and be captured by the slag. Therefore, given a fixed total amount of Al2O3 in the molten steel, the earlier Al2O3 is removed, the higher the purity of the molten steel, and the less likely the continuous casting nozzle turbulence phenomenon will occur. Conversely, the later Al2O3 is removed, the more Al2O3 remains in the molten steel, resulting in lower steel purity. Since the total refining time is limited, argon gas injection stops when the ladle is transported to continuous casting. Therefore, the Al2O3 remaining in the molten steel is no longer adsorbed by the slag and accumulates at the nozzle during casting, forming turbulence. Specifically, during casting, large Al2O3 inclusions remain at the tundish nozzle and agglomerate, growing into even larger inclusions. Because these inclusions have melting points above 1600℃, they do not easily melt at the casting temperature (1500℃), forming a hard, funnel-shaped nozzle that blocks the original diameter nozzle, reducing the amount of molten steel passing through—a phenomenon known as nozzle turbulence. Turbulence often occurs due to changes in the smelting environment, such as excessively delayed slag formation during refining, resulting in insufficient time for inclusion adsorption. Therefore, since the method of the present invention can significantly advance the slag formation time and maintain it for a longer time, there is more time to promote the floating of inclusions, and the cleanliness of molten steel is greatly improved, as shown in Table 1, and the problem of turbulence will not occur.

[0064] The purpose of adding the pre-melting agent of this invention is to form slag that is close to or directly has the characteristics of LF refining slag. After entering LF refining, it can complete slag formation without the need to add lime or with only a small amount of lime and fluorite, based on the rapid melting of slag, thus reducing the burden of LF refining and reducing the slag formation time. The existing pre-melting slag is different. Its purpose is only to form slag. After entering LF refining, it is necessary to add lime and flux - fluorite to further adjust the slag to meet the refining requirements, which is not conducive to the removal of inclusions.

Claims

1. A rapid slag melting method for LF refining, characterized in that, Includes the following steps: S1. Pre-melting agent is added during the tapping process of the converter along with the molten steel flow; The pre-melting flux is composed of the following components by mass percentage: calcium oxide 60-70%, lithium oxide 4-7%, silicon dioxide 3-6%, calcium fluoride 5-10%, magnesium oxide 4-8%, and aluminum oxide 10-15%. When two-thirds of the total volume of molten steel has flowed out, add 500-800 kg of pre-melting agent along with the molten steel. When adding the agent, control the addition speed to 30-50 kg / s. The point where the pre-melting agent is added should always be aligned with the pouring point of the molten steel in the ladle. Do not add any more pre-melting agent 30 seconds before the end of tapping. If the pre-melting flux forms clumps around the molten steel impact zone, and the clump diameter is <30cm, adjust the pre-melting flux addition rate to 15-25kg / s, adjust the ladle to ensure that the molten steel flow impacts the clump location, and promote its rapid and complete melting. When the agglomeration diameter is less than 50 cm and the agglomeration diameter is less than 30 cm, stop adding pre-melting agent, adjust the ladle so that the molten steel flow impacts the agglomeration position, and ensure that the agglomeration is completely melted before adding pre-melting agent at the initial addition rate. When the diameter of the agglomeration is less than 50cm, stop adding pre-melting flux, adjust the ladle to ensure that the molten steel flow impacts the agglomeration location, and continue until the steel tapping is completed; S2. When slag is detected in the converter, close the converter tapping port; S3. Send the ladle to LF refining, measure the oxygen content of the molten steel, and then open the bottom blowing argon valve. Turn the argon gas to 800-1200L / min and stir for 30-60s. During the stirring process, add 10-50kg of aluminum granules to the slag. After stirring, add 50-150kg of lime and turn on the power to adjust the slag and temperature.

2. The LF refining rapid slag melting method according to claim 1, characterized in that: In step S3, if the oxygen content of the molten steel is >50ppm, then add 30-50kg of aluminum granules; If the oxygen content in the molten steel is less than 50 ppm and the oxygen content is less than 20 ppm, then add 10-30 kg of aluminum granules. If the oxygen content is <20ppm, add 10kg of aluminum granules.

3. The LF refining rapid slag melting method according to claim 1, characterized in that: In step S1, the pre-melted flux is pressed into spherical shapes with a diameter of φ80-120mm before use.

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