CN118703737A - A method for producing ultra-pure bearing steel at low cost and high efficiency - Google Patents

Abstract

The invention provides a method for producing ultra-pure bearing steel with low cost and high efficiency, which comprises the following steps: blast furnace smelting, KR or particle Mg desulfurization station desulfurization, top-bottom combined blown converter smelting, LF refining furnace smelting, RH refining furnace smelting and continuous casting; in the smelting process of the top-bottom combined blown converter, waste magnesium refractory materials are crushed into magnesium refractory material particles which are used as converter smelting slag-making raw materials, novel refined slag is added to adsorb inclusion at the end point of converter tapping, and the chemical components of the magnesium refractory material particles are as follows: mgO, C, caO, al ₂O₃、SiO₂, TFe; the novel refining slag comprises the following chemical components: caO and SiO ₂、MgO、Al₂O₃, wherein CaO/Al ₂O₃ is 1.7-2.5, R is 3.0-4.5. By providing new measures for optimizing and improving converter, refining and continuous casting smelting processes, the ultra-pure bearing steel is produced with low cost and high efficiency.

Description

A method for producing ultra-pure bearing steel at low cost and high efficiency

Technical Field

The invention relates to the technical field of steel smelting, and in particular to a method for producing ultra-pure bearing steel at low cost and high efficiency.

Background Art

In the steel industry, bearing steel is recognized as the "king of steel". Due to its harsh service conditions, bearing steel is one of the special steels with the greatest difficulty in production, the most stringent product quality requirements, and the most inspection items. Due to the difficulty in production and the many technical requirements, the production equipment conditions and technical difficulty are relatively high. In particular, the fatigue life of bearing steel mainly depends on the purity of the steel, and the control of inclusions in the bearing steel smelting process is extremely strict. However, in the face of the current severe steel situation in the steel industry, such as high production costs, low steel prices, and a sharp decline in the economic benefits of the steel industry, how to achieve efficient, low-cost, and ultra-pure production in the bearing steel smelting process is of great significance.

This patent, based on the inclusion control characteristics of ultra-pure bearing steel, provides a new way for enterprises to reduce costs and increase efficiency while ensuring the ultra-purity of steel, through new technical measures such as converter raw materials, refined slag design optimization, and process optimization reduction.

Chinese patent CN202311195006.4: discloses a production method of low-titanium bearing steel, which adopts BOF+LF+VD+CC smelting technology, converter end point C≥0.15%, slide plate slag blocking, alloy addition during steel tapping, low-basicity slag ≥3kg/ton steel after furnace addition; LF makes low-basicity slag, no deoxidation operation during smelting, slag removal operation after sampling Ti≤0.0008%, ensure clean slag removal; after slag removal, aluminum wire is fed for deoxidation to ensure Al: 0.040~0.060% of molten steel, lime and low-titanium synthetic slag are added to make high-basicity white slag for deoxidation and S removal, and finished product Ti≤0.0015% bearing steel is successfully developed. This patented technology only improves the process for controlling the low Ti content of bearing steel, and does not involve cost reduction and purity control.

Chinese Patent CN202311158806.9: Provides a method for manufacturing high-homogeneity and high-purity die-cast carburized bearing steel for railways, which includes in sequence: electric furnace smelting, LF refining, RH vacuum degassing, die casting, high-temperature diffusion of ingots, ingot rolling and billet rolling steps; the preparation method of the invention effectively reduces the oxygen content, titanium content, and sulfur content of the steel, reduces the inclusion content, refines the size of microscopic non-metallic inclusions, and the macroscopic inclusion defect is 0. It solves the problem of insufficient purity and density of vacuum degassed die-cast bearing steel in the prior art. This patent provides the key points of the full-process production operation, and adopts die casting production, which is essentially different from the production process of this patent, and does not involve cost reduction issues.

Chinese patent CN202311024814.4: Provides a production process based on magnesium treatment to improve the castability of bearing steel. This patent can control inclusions to MgO through magnesium treatment, and the proportion of MgO inclusions with a size less than 2 microns is controlled to be more than 90%, and the number density of MgO inclusions is less than 260/ ^100mm2 . MgO inclusions do not sinter at the pouring temperature (1470-1495℃), which can greatly increase the number of continuous casting furnaces and the qualified rate of water immersion flaw detection. This patented technology is aimed at increasing the number of continuous casting furnaces. By adopting Mg treatment, the purpose of improving quality is achieved, but it does not involve cost reduction and purity control.

Chinese patent CN202310928546.2: discloses a smelting method for controlling the oxygen content of stainless steel bearings. The stainless steel molten iron from the blast furnace is treated in a desulfurization station, and then high carbon is used for converter smelting. The double slag method is then used to control the basicity and oxidizability of the top slag to achieve the purpose of controlling the oxygen content of the bearing steel. This patent technology also does not involve cost reduction and purity control.

Summary of the invention

The present invention realizes a method for producing ultra-pure bearing steel with low cost and high efficiency through innovative measures such as recycling magnesium-calcium refractory waste in a converter, designing a new type of refined slag, and operating without soft blowing.

In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a method for producing ultra-pure bearing steel with low cost and high efficiency, wherein the method process is as follows: blast furnace smelting → KR or granular Mg desulfurization station desulfurization → top and bottom combined blowing converter smelting → LF refining furnace smelting → RH refining furnace smelting → continuous casting; in the process of top and bottom combined blowing converter smelting, the discarded magnesia refractory material is crushed into magnesia refractory granular material as the raw material for converter slag making, and a new type of refined slag is added at the end of the converter tapping to absorb inclusions.

The chemical composition and content of the magnesium refractory granules are as follows:

MgO 64-90%, C6-15%, CaO 0-5%, Al ₂ O ₃ 0-10%, SiO 0-5% ₂ , TFe 0-5%;

The chemical composition and content of the novel refined slag are as follows:

CaO 49-53%, SiO ₂ 10-16%, MgO 0-8%, Al ₂ O ₃ 20-26%, wherein R 3.0-4.5, R represents binary basicity = CaO/SiO ₂ ratio, CaO/Al ₂ O ₃ is 1.7-2.5.

Preferably, the method for top and bottom combined blowing converter smelting is as follows: 2 to 5 minutes after the oxygen lance is opened in the early stage of converter blowing, a certain amount of magnesia refractory granules is added into the converter for slag making operation, and at the same time, the oxygen lance position is increased from 1200 to 1300 mm to 1500 to 1600 mm, and the ignition oxygen blowing flow rate is increased to 7000 to 12000 m ³ /h. After 2 to 6 minutes of blowing, the lance position is controlled at 1300 mm, and the oxygen supply flow rate is 6500 to 9000 m ^{3 /h. In the late stage of converter smelting, a certain amount of magnesia refractory granules is added again, and the lance position is kept at 1600 mm at the initial stage of feeding, and the oxygen flow rate is 10000 m 3} /h. After 2 minutes, the oxygen supply of the oxygen lance is manually increased in a step-by-step manner, and the blowing lance position is adjusted to 1500 mm, and the oxygen supply flow rate is 19000 m ^{3 /} h. /h, and then gradually reduce the oxygen blowing flow rate according to the slag and decarburization conditions; when pouring the furnace in the later stage of smelting, temperature measurement and sampling are carried out while pouring out 10-30% of the slag, the composition of the molten steel at the end of blowing satisfies: P≤0.010%, C≥0.10%, the terminal molten steel temperature is between 1600 and 1650℃, and the double-layer slag blocking of the slide plate and slag blocking cone is used for steel tapping to prevent slag from falling out during steel tapping.

Preferably, the method of adding the new type of refined slag is to open the ladle argon at the beginning of the converter tapping, blow argon in the ladle throughout the tapping process, stir strongly in the early stage, adjust the argon to weak stirring when the tapping reaches 4/5, add a certain amount of the new type of refined slag at the end of the tapping, and turn off the ladle argon after 3 minutes of addition. In the LF refining and smelting process, the power supply adopts the automatic power supply mode, and the deoxidizer is added after 2-5 minutes of power supply. After 8-12 minutes of power supply, the electrode is started, and the refined slag sample is dipped to detect the slag sample composition. In the refining process, the smelting temperature is within the range of 1500-1550℃, and the refined slag composition is kept close to the B area in Figure 1, which can significantly improve the adsorption capacity of the refined slag for inclusions.

Compared with the prior art, the advantages and positive effects of the present invention are that magnesia refractory materials are the main refractory materials used in the steelmaking production process, and their usage accounts for more than 65% of the total refractory materials. In order to make full use of waste magnesia refractory materials, this patent proposes a smelting technology for recycling waste refractory materials in converter smelting. Since the slag-making material dolomite or light-burned dolomite contains a certain amount of MgO, this patent uses waste magnesia refractory materials that meet the requirements to effectively replace dolomite or light-burned dolomite, so that slag can be quickly formed in the early stage of smelting. At the same time, it can also prevent or reduce the erosion of high-temperature slag on the converter lining, which is beneficial to improve the furnace life. The recycling of waste Since magnesium refractory has a higher surplus furnace temperature, it can consume 2 to 4 tons more scrap steel, increase the scrap steel ratio, and reduce production costs. By using waste magnesium refractory instead of dolomite slag-making material, the steelmaking production cost can be reduced by 2 to 4 yuan/ton of steel; after the new refined slag is used in this patent, the slag is fast and has good fluidity during the refining process, and the ability to absorb inclusions is strong, the purity of the steel is significantly improved, and the nodule problem of the continuous casting submerged nozzle is reduced, and the number of continuous casting furnaces is increased; after the optimization and improvement of the converter, LF refining and RH refining, the purity of the bearing steel is greatly improved, and the slag removal and soft blowing operations can be cancelled, shortening the process flow, improving production efficiency, and reducing production costs.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a distribution diagram of the adsorption capacity of the new refined slag system for Al ₂ O ₃ inclusions;

FIG2 is a diagram showing the effect of inclusion removal before process optimization and improvement in Example 1;

FIG3 is a diagram showing the effect of inclusion removal after process optimization and improvement in Example 1;

FIG4 is a diagram showing the effect of inclusion removal before process optimization and improvement in Example 2;

FIG5 is a diagram showing the effect of inclusion removal after process optimization and improvement in Example 2:

FIG6 is a diagram showing the effect of inclusion removal before process optimization and improvement in Example 3:

FIG. 7 is a diagram showing the effect of inclusion removal after process optimization and improvement in Example 3.

Legend:

DETAILED DESCRIPTION

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Example 1

2-3, this embodiment provides a method for producing ultra-clean bearing steel at low cost and high efficiency.

The new smelting process was tested in a steel company's 100-ton converter, 100-ton LF refining, 100-ton RH refining and 35-ton continuous casting tundish to produce 1 furnace of GCr15 bearing steel. The optimized smelting process flow is: blast furnace → KR or granular Mg desulfurization station → top and bottom combined blowing converter → LF refining furnace → RH refining furnace → continuous casting. The detailed process is as follows:

(1) Blast furnace iron meets the requirements for bearing steel smelting: molten iron tapping temperature 1368°C; molten iron sulfur content 0.026%.

(2) The S content of molten iron after treatment in KR or granular Mg desulfurization station is 0.003%.

(3) Before converter smelting, the discarded magnesia refractory is crushed into granular materials with a particle size of about 40 mm and transported to the high-level silo of the converter as a slag-making material instead of dolomite or light-burned dolomite. The composition and content of the discarded magnesia refractory are: MgO 64%, C15%, CaO 1%, _{Al2O3 10} %, _SiO2 5%, TFe 5%.

(4) 3 minutes after the oxygen lance was opened at the beginning of the converter blowing, 450 kg of waste magnesia refractory granules were added into the converter for slagging operation. At the same time, the oxygen lance position was raised from 1250 mm to 1600 mm, and the ignition oxygen flow rate was increased to 9000 m ³ /h. After 3 minutes of blowing, the lance position was controlled at 1300 mm, and the oxygen flow rate was 8000 m ³ /h.

(5) In the later stage of converter smelting, 400 kg of waste magnesium refractory granules were added again. At the initial stage of feeding, the lance position was maintained at 1600 mm, and the oxygen flow rate was 10000 ^m3 /h. After 2 minutes, the oxygen supply of the oxygen lance was manually increased in steps, and the blowing lance position was adjusted to 1500 mm, and the oxygen flow rate was 19000 ^m3 /h. Then, the blowing oxygen flow rate was gradually reduced according to the slag and decarburization conditions.

(6) When pouring the furnace in the later stage of smelting, temperature measurement and sampling are carried out while pouring out 15% of the slag. The final molten steel composition of blowing is: P 0.010%, C 0.12%, and the final molten steel temperature is 1630℃. The double-layer slag blocking of slide plate and slag blocking cone is used to prevent slag from falling out of the steel.

(7) When the converter starts to tap steel, the ladle argon is opened. During the tapping process, the ladle is blown with argon. Strong stirring is performed in the early stage (reference pressure 1.5 MPa, each argon tumbling diameter 420 mm). When the tapping is 4/5, the argon is adjusted to weak stirring (reference pressure 0.6 MPa, argon tumbling diameter 250 mm). At the end of the tapping, 1600 kg of new refined slag is added, and the ladle argon is turned off 3 minutes after the addition.

(8) LF refining power supply adopts automatic power supply mode. 50kg of deoxidizer is added 5 minutes after power supply. After 10 minutes of power supply, the electrode is started and the new refined slag sample is dipped. The components of the slag sample are as follows:

Element R CaO SiO ₂ MgO Al ₂ O ₃ CaO/Al ₂ O ₃ content 3.8 50 13 5 twenty two 2.27

(9) The RH vacuum holding time is 28 minutes. After converter smelting, LF refining and RH refining optimization and improvement, the purity of the bearing steel is greatly improved, and the post-furnace slag removal and soft blowing operations are eliminated, shortening the process flow, improving production efficiency, and reducing production costs.

(10) Continuous casting: After casting in the tundish and crystallizer, a 180×240 mm rectangular continuous casting billet is formed for high-speed wire rolling.

Example 2

Referring to Figure 4-5, the new smelting process was tested in a steel company's 120-ton converter, 120-ton LF refining, 120-ton RH refining and 40-ton continuous casting tundish to produce 1 furnace of GCr15 bearing steel. The optimized smelting process flow is: blast furnace → KR or granular Mg desulfurization station → top and bottom combined blowing converter → LF refining furnace → RH refining furnace → continuous casting. The detailed process is as follows:

(1) Blast furnace iron production meets the requirements for bearing steel smelting: molten iron temperature is 1395°C; molten iron sulfur content is 0.025%.

(2) The S content of molten iron after treatment in KR or granular Mg desulfurization station is 0.0035%.

(3) Before converter smelting, the discarded magnesia refractory is crushed into particles with a particle size of about 50 mm and transported to the high-level silo of the converter as a slag-making material instead of dolomite or light-burned dolomite. The composition and content of the discarded magnesia refractory are: MgO 85%, C8%, CaO 2%, _{Al2O3 2} %, _SiO2 2%, TFe 1%.

(4) 2 minutes after the oxygen lance was opened at the beginning of the converter blowing, 600 kg of waste magnesia refractory granules were added into the converter for slagging operation. At the same time, the oxygen lance position was raised from 1300 mm to 1600 mm, and the ignition oxygen flow rate was increased to 12000 ^m3 /h. After 6 minutes of blowing, the lance position was controlled at 1300 mm and the oxygen flow rate was 9000 ^m3 /h.

(5) In the later stage of converter smelting, 500 kg of waste magnesium refractory granules were added again. At the initial stage of feeding, the lance position was maintained at 1600 mm, and the oxygen flow rate was 10000 ^m3 /h. After 2 minutes, the oxygen supply of the oxygen lance was manually increased in steps, and the blowing lance position was adjusted to 1500 mm, and the oxygen flow rate was 19000 ^m3 /h. Then, the blowing oxygen flow rate was gradually reduced according to the slag and decarburization conditions.

(6) When pouring out the furnace in the later stage of smelting, temperature measurement and sampling are carried out while pouring out 30% of the slag. The composition of the molten steel at the end of blowing is: P 0.009%, C 0.15%, and the end temperature of the molten steel is 1650℃. The double-layer slag blocking of the slide plate and the slag blocking cone is used to prevent slag from falling out of the steel.

(7) When the converter starts to tap steel, the argon gas in the ladle is turned on. During the tapping process, the ladle is blown with argon. Strong stirring is performed in the early stage (reference pressure 1.3 MPa, and the diameter of each argon roll is 380 mm). When the tapping is 4/5, the argon gas is adjusted to weak stirring (reference pressure 0.4 MPa, and the diameter of the argon roll is 230 mm). At the end of the tapping, 1200 kg of new refined slag is added, and the argon gas in the ladle is turned off 3 minutes after the addition.

(8) LF refining power supply adopts automatic power supply mode. 60kg of deoxidizer is added 4 minutes after power supply. After 12 minutes of power supply, the electrode is started and the new refined slag sample is dipped. The components of the slag sample are as follows:

Element R CaO SiO ₂ MgO Al ₂ O ₃ CaO/Al ₂ O ₃ content 3.5 49 14 6 twenty four 2.04

(9) The RH vacuum holding time is 33 minutes. After converter smelting, LF refining and RH refining optimization and improvement, the purity of the bearing steel is greatly improved, and the post-furnace slag removal and soft blowing operations are eliminated, shortening the process flow, improving production efficiency, and reducing production costs.

(10) Continuous casting: After casting in the tundish and crystallizer, a 180×240 mm rectangular continuous casting billet is formed for high-speed wire rolling.

Example 3

Referring to Figure 6-7, the new smelting process was tested in a steel company's 110-ton converter, 110-ton LF refining, 110-ton RH refining and 38-ton continuous casting tundish to produce 1 furnace of GCr15 bearing steel. The optimized smelting process flow is: blast furnace → KR or granular Mg desulfurization station → top and bottom combined blowing converter → LF refining furnace → RH refining furnace → continuous casting. The detailed process is as follows:

(1) Blast furnace iron meets the requirements for bearing steel smelting: molten iron tapping temperature 1385°C; molten iron sulfur content 0.024%.

(2) The sulfur content of molten iron after treatment in KR or granular Mg desulfurization station is 0.004%.

(3) Before converter smelting, the discarded magnesia refractory is crushed into particles with a particle size of about 10 mm and transported to the high-level silo of the converter as a slag-making material instead of dolomite or light-burned dolomite. The composition and content of the discarded magnesia refractory are: MgO 90%, C6%, CaO 0%, _{Al2O3 4} %, _SiO2 0%, TFe 0%.

(4) 2 minutes after the oxygen lance was opened at the beginning of the converter blowing, 300 kg of waste magnesia refractory granules were added into the converter for slagging operation. At the same time, the oxygen lance position was raised from 1200 mm to 1500 mm, and the ignition oxygen flow rate was increased to 7000 m ³ /h. After 2 minutes of blowing, the lance position was controlled at 1300 mm, and the oxygen flow rate was 6500 m ³ /h.

(5) In the later stage of converter smelting, 300 kg of waste magnesium refractory granules were added again. At the initial stage of feeding, the lance position was maintained at 1600 mm, and the oxygen flow rate was 10,000 m ³ /h. After 2 minutes, the oxygen supply of the oxygen lance was manually increased in steps, and the blowing lance position was adjusted to 1500 mm, and the oxygen flow rate was 19,000 m ³ /h. Then, the blowing oxygen flow rate was gradually reduced according to the slag and decarburization conditions.

(6) When pouring out the furnace in the later stage of smelting, temperature measurement and sampling are carried out while pouring out 20% of the slag. The final molten steel composition of blowing is: P 0.009%, C 0.15%, and the final molten steel temperature is 1650℃. The double-layer slag blocking of the slide plate and the slag blocking cone is used to prevent slag from falling out of the steel.

(7) When the converter starts to tap steel, the argon gas in the ladle is turned on. During the tapping process, the ladle is blown with argon. Strong stirring is performed in the early stage (reference pressure 1.3 MPa, and the diameter of each argon roll is 380 mm). When the tapping is 4/5, the argon gas is adjusted to weak stirring (reference pressure 0.4 MPa, and the diameter of the argon roll is 230 mm). At the end of the tapping, 1800 kg of new refined slag is added, and the argon gas in the ladle is turned off 3 minutes after the addition.

(8) LF refining power supply adopts automatic power supply mode. 40kg of deoxidizer is added 2 minutes after power supply. After 8 minutes of power supply, the electrode is started and the refined slag sample is dipped. The components of the slag sample are as follows:

Element R CaO SiO ₂ MgO Al ₂ O ₃ CaO/Al ₂ O ₃ content 3.06 49 16 4.5 26 1.88

(9) The RH vacuum holding time is 33 minutes. After converter smelting, LF refining and RH refining optimization and improvement, the purity of the bearing steel is greatly improved, and the post-furnace slag removal and soft blowing operations are eliminated, shortening the process flow, improving production efficiency, and reducing production costs.

(10) Continuous casting: After casting in the tundish and crystallizer, a 180×240 mm rectangular continuous casting billet is formed for high-speed wire rolling.

The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims (3)

1. A method for producing ultra-pure bearing steel at low cost and high efficiency, characterized in that the method process is as follows: blast furnace smelting → KR or granular Mg desulfurization station desulfurization → top and bottom combined blowing converter smelting → LF refining furnace smelting → RH refining furnace smelting → continuous casting; in the process of top and bottom combined blowing converter smelting, the discarded magnesia refractory material is crushed into magnesia refractory granules as the raw material for converter slag making, and a new type of refined slag is added at the end of the converter tapping to absorb inclusions, and the chemical composition and content of the magnesia refractory granules are as follows: MgO 64-90%, C6-15%, CaO 0-5%, Al ₂ O ₃ 0-10%, SiO 0-5% ₂ , TFe 0-5%; The chemical composition and content of the novel refined slag are as follows: CaO 49-53%, SiO ₂ 10-16%, MgO 0-8%, Al ₂ O ₃ 20-26%, wherein R 3.0-4.5, R represents binary basicity = CaO/SiO ₂ ratio, CaO/Al ₂ O ₃ is 1.7-2.5. 2. The method for producing ultra-pure bearing steel with low cost and high efficiency according to claim 1 is characterized in that the method for top and bottom combined blowing converter smelting is as follows: 2 to 5 minutes after the oxygen lance is opened in the early stage of converter blowing, a certain amount of magnesium refractory granules is added into the converter for slag making operation, and at the same time, the oxygen lance position is increased from the original 1200 to 1300 mm to 1500 to 1600 mm, and the ignition oxygen blowing flow rate is increased to 7000 to 12000 m ³ /h. After 2 to 6 minutes of blowing, the lance position is controlled at 1300 mm, and the oxygen supply flow rate is 6500 to 9000 m ³ /h; in the late stage of converter smelting, a certain amount of magnesium refractory granules is added again, the lance position is maintained at 1600 mm at the initial stage of feeding, and the oxygen flow rate is 10000 m ^{3 /h. After 2 minutes, the oxygen supply of the oxygen lance is manually increased in a step-by-step manner, and the blowing lance position is adjusted to 1500 mm, and the oxygen supply flow rate is 19000 m 3 /} h. /h, and then gradually reduce the oxygen blowing flow rate according to the slag and decarburization conditions; when pouring the furnace in the later stage of smelting, temperature measurement and sampling are carried out while pouring out 10-30% of the slag, the composition of the molten steel at the end of blowing satisfies: P≤0.010%, C≥0.10%, the terminal molten steel temperature is between 1600 and 1650℃, and the double-layer slag blocking of the slide plate and slag blocking cone is used for steel tapping to prevent slag from falling out during steel tapping. 3. The method for low-cost and high-efficiency production of ultra-clean bearing steel according to claim 1 is characterized in that: the method of adding the new refined slag is to open the ladle argon at the beginning of converter tapping, blow argon into the ladle throughout the tapping process, perform strong stirring in the early stage, adjust the argon to weak stirring when the tapping is 4/5, add a certain amount of the new refined slag at the end of tapping, turn off the ladle argon after 3 minutes of adding, and in the LF refining and smelting process, the power supply adopts the automatic power supply mode, the deoxidizer is added 2-5 minutes after the power supply, the electrode is started 8-12 minutes after the power supply, and the refined slag sample is dipped to detect the slag sample composition.