Method for improving submerged arc heating effect of LF furnace through hot slag circulation

Abstract

The invention relates to the technical field of LF (Ladle Furnace) refining, in particular to a method for improving the submerged arc heating effect of an LF furnace through hot slag circulation, which comprises the following steps of: after molten steel in a steel ladle is poured, closing a water gap of the steel ladle, retaining residual hot slag in the steel ladle, hoisting the steel ladle away from a large ladle turret of a continuous casting machine by using a crown block; the residual hot slag in the steel ladle is poured into the steel ladle after converter tapping, the circulating hot slag floats on the surface of the molten steel due to the fact that the density is lower than that of the molten steel, the molten steel containing the hot slag is hoisted from a converter argon blowing station to an LF furnace refining station for refining treatment, an LF furnace lower electrode normally conducts refining heating and molten steel component adjustment, and the molten steel is cooled to the room temperature; after refining is completed, the steel ladle is hoisted to a continuous casting machine for pouring, after molten steel pouring is completed, hot slag in the steel ladle is recycled again, the slag former adding amount is reduced, the refining time is shortened, inclusions in the molten steel can be reduced, the purity of the molten steel can be improved, and efficient refining is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of LF refining, and in particular to a method for improving the submerged arc heating effect of an LF furnace through hot slag circulation. Background Art

[0002] LF refining is one of the main methods of off-furnace refining. It was successfully developed in Japan in the early 1970s and is currently the most widely used off-furnace refining equipment. It is also an indispensable step in the smelting of high-quality steel. It has strong refining capabilities and is suitable for the production of ultra-low sulfur and ultra-low oxygen steels. It has both arc heating functions, high thermal efficiency, a large temperature rise range, and high temperature control accuracy within ±5°C. It also has stirring and alloying functions, which facilitates narrow composition control. The submerged arc in the LF furnace refining process plays a vital role in LF refining desulfurization. The submerged arc operation has the advantages of stabilizing the arc, improving heating efficiency, protecting the furnace lining, reducing the consumption of electrode materials and furnace lining refractory materials, and effectively preventing molten steel oxidation and nitrogen absorption. It also increases the slag interfacial area and improves the kinetic conditions for deoxidation and desulfurization.

[0003] To achieve smooth steelmaking production, stable control of tundish superheat, and efficient steelmaking, most steel mills currently utilize a converter-LF refining-continuous casting process. This utilizes the LF furnace's rapid and precise temperature rise to achieve both intermediate transitions and stable control. However, during production, poor arc submergence often leads to graphite electrode breakage and a significant reduction in the life of refractory materials at the ladle slag line. This, coupled with poor refining temperature rise and low desulfurization rates when the molten iron contains high sulfur, severely impacts the refining cycle. Shortening the refining cycle has become crucial for efficient steelmaking systems.

[0004] In response to the above problems, the inventor team proposed a method for improving the submerged arc heating effect of the LF furnace by circulating hot slag. The foamed submerged arc technology is used to reduce the radiant heat loss of the arc, improve the heating efficiency, and solve the problems of poor submerged arc effect, low power transmission efficiency and low desulfurization rate in the early stage of refining. It aims to shorten the refining cycle and achieve efficient refining. Summary of the Invention

[0005] In order to solve the above-mentioned defects in the prior art, the purpose of the present invention is to provide a method for improving the submerged arc heating effect of the LF furnace by circulating hot slag.

[0006] A method for improving the submerged arc heating effect of an LF furnace by circulating hot slag, comprising the following steps:

[0007] S1. Close the ladle nozzle to retain the hot slag;

[0008] S2. The ladle is lifted off the ladle turret;

[0009] S3, hot slag is poured into the ladle after the converter taps out steel;

[0010] S4, forming a hot slag layer on the surface of the molten steel;

[0011] S5, the ladle is transferred to the LF furnace refining station;

[0012] S6, LF furnace refining;

[0013] S7, continuous casting machine pouring;

[0014] S8. Recycling of hot slag.

[0015] Furthermore, the step S1 closes the ladle nozzle to retain the hot slag, specifically, after the molten steel in the ladle is poured, the ladle nozzle is closed to retain the remaining hot slag in the ladle.

[0016] Furthermore, in step S2, the ladle is lifted off the ladle turret, specifically, the ladle is lifted off the ladle turret of the continuous casting machine by using an overhead crane, and is lifted to the top of the converter argon blowing station to wait.

[0017] Furthermore, in step S3, the hot slag is poured into the ladle after the steel is tapped from the converter. Specifically, the hot slag remaining in the ladle is poured into the ladle after the steel is tapped from the converter.

[0018] Furthermore, in step S4, a hot slag layer is formed on the surface of the molten steel. Specifically, the circulating hot slag floats on the surface of the molten steel to form a hot slag layer on the surface of the molten steel. The thickness of the hot slag layer is 40 to 60 mm, and the height between the hot slag surface and the edge of the ladle is greater than or equal to 200 mm, which meets the requirements of the refining process standards and avoids the molten steel from being overfilled and churning during the refining process, thereby overflowing from the ladle and causing an accident.

[0019] Preferably, step S4 forms a hot slag layer on the surface of the molten steel. Specifically, the circulating hot slag floats on the surface of the molten steel to form a hot slag layer on the surface of the molten steel. The thickness of the hot slag layer is 50 mm, and the height between the hot slag surface and the edge of the ladle is greater than or equal to 200 mm, which meets the requirements of the refining process standards and avoids the molten steel from being overfilled and churning during the refining process, thereby overflowing from the ladle and causing an accident.

[0020] Furthermore, in step S5, the ladle is transferred to the LF furnace refining station. Specifically, an overhead crane is used to lift the molten steel containing hot slag from the converter argon blowing station to the LF furnace refining station for refining treatment, and the temperature of the molten steel is measured before refining.

[0021] Furthermore, the step S6, LF furnace refining, specifically, the LF furnace lower electrode is normally refined and heated and the composition of the molten steel is adjusted.

[0022] Furthermore, the refining temperature is increased and the composition of the molten steel is adjusted. Specifically, a slag-forming agent is added 3-4 minutes after the first lower electrode is heated. The slag-forming agent is lime. The amount of slag-forming agent added corresponds to the amount of molten steel, which is 2.3 kg / ton per ton of steel. The first heating of the lower electrode is completed 6-8 minutes after the lower electrode is heated. The molten steel temperature is measured, the heating rate is calculated, a molten steel racket sample is taken and sent to the laboratory for analysis. The lower electrode is heated for the second time, and a recarburizer is added to adjust the composition. The second time is measured at a heating rate of 5 degrees / minute. According to the first temperature measurement result and the need to adjust the composition of the second lower electrode, the time range required for the lower electrode is calculated. The outlet temperature range after refining is 1555-1565 degrees. The refining is stopped, the molten steel temperature is measured, and a molten steel racket sample is taken for testing.

[0023] S7, continuous casting machine casting, after S6 refining is completed, it is hoisted to the continuous casting machine for casting.

[0024] The molten steel racket sample refers to a molten steel sampler that is a racket sampler, and the molten steel is in the shape of a racket after solidification.

[0025] Furthermore, the hot slag is recycled in step S8, specifically, after the molten steel is poured, the hot slag in the ladle is recycled again.

[0026] The beneficial effects of the present invention are:

[0027] 1. The hot slag has a high temperature and floats on the surface of the molten steel to keep the molten steel warm and isolate the air, thereby increasing the temperature of the molten steel when it enters the LF furnace and reducing air intake. When the electrode is lowered for the first time in the LF furnace, the foamed submerged arc technology can be realized to improve the arc submergence effect, promote the rapid heating of each stage of the LF furnace refining, especially the first electrode lowering stage, which can reduce the electricity cost of refining.

[0028] 2. Rapid heating promotes the rapid formation of white slag, resulting in a good refined slag state. The sampling is highly representative when taking molten steel racket samples, which is beneficial to component analysis and improves the reliability of the results. By improving the submerged arc effect, arc breakdown is avoided, thereby reducing the impact of the arc on the ladle bricks in the ladle slag line area, extending the ladle life, and reducing the cost of refractory materials.

[0029] 3. Hot slag is directly recycled, and its composition is consistent with the control requirements of the next refining slag. In the early stage of LF furnace refining, slag-forming agent can be omitted to facilitate rapid temperature rise in the early stage. After the temperature rises in the middle and late stages, slag adjustment can be carried out according to the slag state. At this time, the molten steel temperature is high and the slag-forming agent melts quickly, which has little effect on the electrode temperature rise. The amount of slag-forming agent added can be reduced, the refining time can be shortened, and the inclusions in the molten steel can be reduced to improve the purity of the molten steel. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to specific embodiments. The exemplary embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0031] Example 1

[0032] A method for improving the submerged arc heating effect of an LF furnace by circulating hot slag, comprising the following steps:

[0033] S1. Closing the ladle nozzle to retain the hot slag. Specifically, after pouring the molten steel in the ladle, closing the ladle nozzle to retain the remaining hot slag in the ladle.

[0034] S2. The ladle is lifted off the ladle turret. Specifically, an overhead crane is used to lift the ladle off the ladle turret of the continuous casting machine and transport it to the top of the converter argon blowing station and wait.

[0035] S3. The hot slag is poured into the ladle after the converter has tapped the steel. Specifically, the hot slag remaining in the ladle is poured into the ladle after the converter has tapped the steel.

[0036] S4. A hot slag layer is formed on the surface of the molten steel. Specifically, the circulating hot slag floats on the surface of the molten steel to form a hot slag layer on the surface of the molten steel. The thickness of the hot slag layer is 50 mm, and the height between the hot slag surface and the edge of the ladle is greater than or equal to 200 mm, which meets the requirements of the refining process standards and prevents the molten steel from being overfilled and churning during the refining process, thereby overflowing from the ladle and causing accidents.

[0037] S5. The ladle is transferred to the LF furnace refining station. Specifically, an overhead crane is used to lift the molten steel containing hot slag from the converter argon blowing station to the LF furnace refining station for refining treatment. The temperature of the molten steel is measured before refining.

[0038] S6, LF furnace refining, the LF furnace lower electrode is normally refined and heated and the molten steel is adjusted in composition, and after refining is completed, it is hoisted to the continuous casting machine for casting. The refining and heating and molten steel composition adjustment are specifically as follows: 3 minutes after the first lower electrode is heated, a slag-forming agent is added. The slag-forming agent is lime. The amount of slag-forming agent added corresponds to the amount of molten steel, which is 2.3 kg / ton per ton of steel. The first heating of the lower electrode is completed after 7 minutes, the molten steel temperature is measured, the heating rate is calculated, a molten steel racket sample is taken and sent to the laboratory for analysis, the second lower electrode is heated, and a recarburizer is added to adjust the composition. The second time is measured at a heating rate of 5 degrees / minute. According to the first temperature measurement result and the second lower electrode composition adjustment, the required lower electrode time range is calculated. The outlet temperature range after refining is 1560 degrees, refining is stopped, and a molten steel racket sample is taken for testing. The molten steel racket sample refers to a molten steel sampler that is a racket sampler. The molten steel takes the shape of a racket after solidification.

[0039] S7, continuous casting machine casting, after S6 refining is completed, it is hoisted to the continuous casting machine for casting.

[0040] S8, hot slag recycling, specifically, after the molten steel is poured, the hot slag in the ladle is recycled again.

[0041] Example 2

[0042] A method for improving the submerged arc heating effect of an LF furnace by circulating hot slag, comprising the following steps:

[0043] S1 closes the ladle nozzle to retain the hot slag. Specifically, after the molten steel in the ladle is poured, the ladle nozzle is closed to retain the remaining hot slag in the ladle.

[0044] The S2 ladle is lifted off the ladle turret. Specifically, an overhead crane is used to lift the ladle off the ladle turret of the continuous casting machine and transport it to the top of the converter argon blowing station to wait.

[0045] S3 hot slag is poured into the ladle after the converter has tapped the steel. Specifically, the hot slag remaining in the ladle is poured into the ladle after the converter has tapped the steel.

[0046] S4 forms a hot slag layer on the surface of the molten steel. Specifically, the circulating hot slag floats on the surface of the molten steel to form a hot slag layer on the surface of the molten steel. The thickness of the hot slag layer is 40 mm, and the height between the hot slag surface and the edge of the ladle is greater than or equal to 200 mm, which meets the requirements of the refining process standards and avoids the molten steel from being too full and churning during the refining process, thereby overflowing from the ladle and causing accidents.

[0047] The S5 ladle is transferred to the LF furnace refining station. Specifically, an overhead crane is used to lift the molten steel containing hot slag from the converter argon blowing station to the LF furnace refining station for refining treatment, and the molten steel temperature is measured before refining.

[0048] S6 LF furnace refining: The LF furnace lower electrode undergoes normal refining and heating, and the molten steel is adjusted for composition. After refining is complete, it is hoisted to the continuous casting machine for casting. Specifically, after the first lower electrode heating for 4 minutes, a slag-forming agent is added. The slag-forming agent is lime, and the amount of slag-forming agent added corresponds to the amount of molten steel, which is 2.3 kg / ton of steel. The first heating is completed after 8 minutes. The molten steel temperature is measured, the heating rate is calculated, and a racket sample of the molten steel is taken and sent to the laboratory for analysis. The second lower electrode heating is performed, and a recarburizer is added to adjust the composition. The second heating rate is calculated at 5 degrees / minute. Based on the first temperature measurement results and the composition adjustment required for the second lower electrode, the required time range for the lower electrode is calculated. The outlet temperature range for refining is 1555 degrees. Refining is stopped, and a racket sample of the molten steel is taken for analysis. The racket sample of the molten steel refers to the molten steel sampler using a racket sampler, which takes the shape of a racket after solidification.

[0049] S7, continuous casting machine casting, after S6 refining is completed, it is hoisted to the continuous casting machine for casting.

[0050] S8 hot slag recycling, specifically, after the molten steel is poured, the hot slag in the ladle is recycled again.

[0051] Example 3

[0052] A method for improving the submerged arc heating effect of an LF furnace by circulating hot slag, comprising the following steps:

[0053] S1 closes the ladle nozzle to retain the hot slag. Specifically, after the molten steel in the ladle is poured, the ladle nozzle is closed to retain the remaining hot slag in the ladle.

[0054] The S2 ladle is lifted off the ladle turret. Specifically, an overhead crane is used to lift the ladle off the ladle turret of the continuous casting machine and transport it to the top of the converter argon blowing station to wait.

[0055] S3 hot slag is poured into the ladle after the converter has tapped the steel. Specifically, the hot slag remaining in the ladle is poured into the ladle after the converter has tapped the steel.

[0056] S4 forms a hot slag layer on the surface of the molten steel. Specifically, the circulating hot slag floats on the surface of the molten steel to form a hot slag layer on the surface of the molten steel. The thickness of the hot slag layer is 60 mm, and the height between the hot slag surface and the edge of the ladle is greater than or equal to 200 mm, which meets the requirements of the refining process standards and avoids the molten steel from being too full and churning during the refining process, thereby overflowing from the ladle and causing accidents.

[0057] The S5 ladle is transferred to the LF furnace refining station. Specifically, an overhead crane is used to lift the molten steel containing hot slag from the converter argon blowing station to the LF furnace refining station for refining treatment, and the molten steel temperature is measured before refining.

[0058] In the S6 LF furnace, the lower electrode in the LF furnace undergoes normal refining and heating, and the molten steel is adjusted for composition. After refining is complete, the molten steel is hoisted to the continuous casting machine for casting. Specifically, a slag-forming agent (lime) is added 3 minutes after the first lower electrode heating. The slag-forming agent is lime, and the amount of slag-forming agent added corresponds to the amount of molten steel, equivalent to 2.3 kg / ton of steel. The first heating is completed 6 minutes after the lower electrode heating. The molten steel temperature is measured, the heating rate is calculated, and a racket sample of the molten steel is taken and sent to the laboratory for analysis. The lower electrode is heated a second time, and a recarburizer is added to adjust the composition. The second heating rate is calculated at 5 degrees / minute. The required time range for the lower electrode heating is calculated based on the first temperature measurement and the composition adjustment required for the second lower electrode heating. The outlet temperature range for refining is 1565 degrees. Refining is stopped, and a racket sample of the molten steel is taken for analysis. The racket sample of the molten steel refers to a racket-shaped molten steel sampler, which forms a racket shape after solidification.

[0059] S7, continuous casting machine casting, after S6 refining is completed, it is hoisted to the continuous casting machine for casting.

[0060] S8 hot slag recycling, specifically, after the molten steel is poured, the hot slag in the ladle is recycled again.

[0061] To verify the effectiveness of the present invention, the inventors conducted a verification test, the excerpt of which is as follows:

[0062] Test example

[0063] The 1# converter, 1# LF, and 1# continuous casting machine produce HRB500E steel. After the 1# continuous casting machine finished pouring heat 25100025 of molten steel (using ladle 1), the 1# ladle nozzle was closed, leaving the hot slag (approximately 1000kg) inside the ladle. The 1# ladle was hoisted by an overhead crane to the top of the argon blowing station of the 1# converter and waited. Meanwhile, tapping heat 25100027 of the 1# converter was complete, and the ladle car transported the molten steel (ladle 2) to the argon blowing station. The overhead crane slowly poured the hot slag from ladle 1 into ladle 2, allowing it to float above the molten steel in ladle 2. The height between the hot slag surface and the ladle rim was 300mm, meeting refining requirements. The #2 ladle was hoisted to the #1 station of the #1 LF furnace using an overhead crane. The ladle car at station #1 was then driven to the refining station for refining. The molten steel temperature was measured at 1524°C before refining. The LF furnace began its first electrode heating operation. Surface appearance indicated minimal ladle slag splashing during the refining process, minimal arc heating noise, and minimal electrode vibration. Three minutes after the first electrode heating, a slagging agent (200 kg of lime) was added. Refining was stopped after six minutes. The molten steel temperature was measured at 1536°C. A racket sample of the molten steel was taken and sent to the laboratory for analysis. The results showed 0.20% carbon, 0.45% silicon, 1.50% manganese, and 0.065% vanadium. The lower electrode was heated for the second time, and 30 kg of recarburizer was added. Refining was stopped after 5 minutes. The molten steel temperature was measured at 1560°C. A racket sample of the molten steel was taken for analysis, revealing 0.23% carbon, 0.44% silicon, 1.52% manganese, and 0.065% vanadium. The second ladle was moved from the refining station to the first station and hoisted by an overhead crane to the first continuous casting machine for pouring. After pouring, the sprue of the second ladle was closed, and the hot slag in the ladle was recycled.

[0064] The first heating rate was 2.0°C / min; the second heating rate was 4.8°C / min.

[0065] The steel sample taken after the first heating is more representative. The actual composition of the sample taken after the second addition of recarburizer is consistent with the calculation result of the first addition of 30kg recarburizer.

[0066] Comparative Example

[0067] The 1# converter, 1# LF, and 1# continuous casting machine produced HRB500E steel. Heat 25100024 of the 1# converter was tapped, and the ladle (#3) filled with molten steel was transferred to the argon blowing station via a ladle car. An overhead crane hoisted the #3 ladle to the #1 station of the 1# LF, and the ladle car was driven to the refining station for refining. The molten steel temperature before refining was 1522°C. The LF furnace began its first electrode heating. Surface phenomena revealed significant ladle slag splashing out of the ladle during refining, loud arc heating noise, and significant electrode vibration. Three minutes after the first electrode heating, a slagging agent (400 kg of lime) was added. Refining was stopped after six minutes. The molten steel temperature was measured at 1527°C. A racket sample of the molten steel was taken and sent to the laboratory for analysis. The results showed 0.19% carbon, 0.47% silicon, 1.48% manganese, and 0.062% vanadium. The second lower electrode heating cycle was followed by a 5-minute refining stop. The molten steel temperature was measured at 1540°C, and a steel sample was taken for analysis. The results showed 0.21% carbon, 0.44% silicon, 1.54% manganese, and 0.064% vanadium. The third lower electrode heating cycle was followed by the addition of 20 kg of recarburizer. Refining was stopped after 5 minutes, and the molten steel temperature was measured at 1560°C. A steel sample was taken for analysis, and the results showed 0.23% carbon, 0.45% silicon, 1.55% manganese, and 0.065% vanadium. Ladle 3 was moved from the refining station to the 1# station and hoisted to the 1# continuous casting machine using an overhead crane for pouring. After pouring, the sprue of ladle 2 was closed, and the hot slag in the ladle was poured into the slag pot.

[0068] The first heating rate was 0.83°C / min, the second heating rate was 2.6°C / min, and the third heating rate was 4.0°C / min.

[0069] The steel sample taken after the first heating was poorly representative, with distorted chemical composition. The second lower electrode was not adjusted for composition, but the actual composition compared to the first heating showed a 0.02% increase in carbon, a 0.03% decrease in silicon, a 0.06% increase in manganese, and a 0.002% increase in vanadium.

[0070] For comparison, the power supply time is 19 minutes. For every 1 minute increase in power supply time, the electricity cost increases by 1.8 yuan per ton of steel.

[0071] Although the present invention has been described in detail above through general explanations, specific embodiments, and experimental comparisons, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A method for improving the submerged arc heating effect of an LF furnace by circulating hot slag, characterized in that: The steps include: S1. Close the ladle nozzle to retain the hot slag; S2. The ladle is lifted off the ladle turret; S3, hot slag is poured into the ladle after the converter taps out steel; S4, forming a hot slag layer on the surface of the molten steel; S5, the ladle is transferred to the LF furnace refining station; S6, LF furnace refining; S7, continuous casting machine pouring; S8. Recycling of hot slag.

2. The method for improving the submerged arc heating effect of LF furnace by hot slag circulation according to claim 1, characterized in that: The step S1 closes the ladle nozzle to retain the hot slag. Specifically, after the molten steel in the ladle is poured, the ladle nozzle is closed to retain the remaining hot slag in the ladle.

3. The method for improving the submerged arc heating effect of LF furnace by hot slag circulation according to claim 1, characterized in that: The step S2 of lifting the ladle off the ladle turret is specifically to use an overhead crane to lift the ladle off the ladle turret of the continuous casting machine.

4. The method for improving the submerged arc heating effect of LF furnace by hot slag circulation according to claim 1, characterized in that: The step S3 of pouring the hot slag into the ladle after the converter has tapped steel is specifically to pour the remaining hot slag in the ladle into the ladle after the converter has tapped steel.

5. The method for improving the submerged arc heating effect of LF furnace by hot slag circulation according to claim 1, characterized in that: The step S4 forms a hot slag layer on the surface of the molten steel. Specifically, the circulating hot slag floats on the surface of the molten steel to form a hot slag layer on the surface of the molten steel. The layer thickness is 40 to 60 mm.

6. The method for improving the submerged arc heating effect of LF furnace by hot slag circulation according to claim 5, characterized in that: The step S4 forms a hot slag layer on the surface of the molten steel. Specifically, the circulating hot slag floats on the surface of the molten steel to form a hot slag layer on the surface of the molten steel. The layer thickness is 50 mm.

7. The method for improving the submerged arc heating effect of LF furnace by hot slag circulation according to claim 1, characterized in that: The step S5 of transferring the ladle to the LF furnace refining station is specifically to lift the molten steel containing the hot slag from the converter argon blowing station to the LF furnace refining station for refining treatment.

8. The method for improving the submerged arc heating effect of LF furnace by hot slag circulation according to claim 1, characterized in that: The step S6, LF furnace refining, specifically includes refining and heating the lower electrode of the LF furnace and adjusting the composition of the molten steel. After refining, the molten steel is hoisted to the continuous casting machine for casting.

9. The method for improving the submerged arc heating effect of an LF furnace by hot slag circulation according to claim 8, characterized in that: The refining temperature is increased and the composition of the molten steel is adjusted, specifically, a slag-forming agent is added 3-4 minutes after the first lower electrode is heated, the slag-forming agent is lime, and the amount of slag-forming agent added corresponds to the amount of molten steel, which is 2.3kg / ton per ton of steel. The first heating is completed after 6-8 minutes of the lower electrode, the molten steel temperature is measured, the heating rate is calculated, a molten steel racket sample is taken and sent to the laboratory for analysis, the lower electrode is heated for the second time, and a recarburizer is added to adjust the composition. The second time is measured at a heating rate of 5 degrees / minute. According to the first temperature measurement result and the need to adjust the composition of the second lower electrode, the time range for the lower electrode is calculated. The outlet temperature range after refining is 1555-1565 degrees, the refining is stopped, the molten steel temperature is measured, and a molten steel racket sample is taken for analysis.

10. The method for improving the submerged arc heating effect of LF furnace by hot slag circulation according to claim 1, characterized in that: The step S8 of recycling the hot slag is specifically to recycle the hot slag in the ladle after the molten steel is poured.