A method for low-cost and efficient dephosphorization of bearing steel

Abstract

The application provides a low-cost and high-efficiency dephosphorization method for bearing steel, which comprises the following steps: before molten iron is poured into a converter, a pre-sequenced ladle slag containing refining slag is poured into a ladle; the molten iron containing the refining slag is poured into the converter, and blast furnace sinter or return ore is added; the amount of lime added in the early stage of converter smelting is reduced to 10-14 kg / t; in order to match the adjustment and change of the slag material, the oxygen lance position and the oxygen flow in the early stage of converter smelting are adjusted, and then the smelting enters into the middle stage; in the middle and late stages of smelting, the amount of dolomite added is reduced by 8-11 kg / t, and the oxygen lance position and the oxygen supply amount are adjusted; the final slag control requirements are as follows: basicity R=2.0-3.5, FeO content 2-15%, MgO content 3-15%, and P2O5 content ≤5%; after the converter is tapped, a dephosphorization agent is used for slag washing and dephosphorization in the tapping process after the converter.

Description

Technical Field

[0001] This application belongs to the field of iron and steel smelting technology, and mainly relates to a low-cost and high-efficiency dephosphorization method for bearing steel. Background Technology

[0002] With the development and technological advancements in industries such as national defense, transportation, petroleum, automobiles, aircraft, instrumentation, and machinery, the quality requirements for steel materials are becoming increasingly stringent, particularly regarding the content of impurities such as phosphorus in steel. This is especially true for high-life bearing steel, often referred to as the "king of steels," where the phosphorus content requirements are even more stringent. However, during the smelting process, when the phosphorus content in steel reaches below 0.013%, dephosphorization becomes more difficult, more costly, and less efficient.

[0003] Given the current severe situation in the domestic steel industry, including high production costs, low steel prices, and a significant decline in economic benefits, it is of great significance to achieve efficient and low-cost dephosphorization in the smelting process of bearing steel.

[0004] Chinese Patent CN112029949B discloses a method for treating zinc-containing scrap steel using a converter full three-stage dephosphorization smelting process. The method involves dephosphorizing in a dephosphorization furnace, followed by decarburization of the dephosphorized semi-steel in a decarburization furnace. This smelting method adds a step to the dephosphorization process, reducing smelting efficiency.

[0005] Chinese Patent CN113337662A discloses a method for improving the dephosphorization effect during the dephosphorization period of a converter for high-phosphorus titanium-containing molten iron. This method involves controlling the excessive formation of TiO2 in the slag during the early stage of the dephosphorization process through measures such as slag removal and retention at the end of the previous converter smelting cycle, adding lime and other slag materials in batches, and adjusting the lance position and oxygen supply intensity. This results in a dephosphorization rate exceeding 65% during the dephosphorization period. However, this patent is specifically for treating high-phosphorus titanium-containing molten iron, and the smelting operations are not applicable to the production of bearing steel.

[0006] Chinese Patent CN113621756A: A control method for improving the dephosphorization effect in the early stage of converter steelmaking. This method involves adding a dephosphorizing agent (made from a mixture of fine-particle lime and iron oxide scale) to the furnace along with scrap steel, and adding lime and ore in batches according to the rate of temperature rise in the furnace. This improves the dephosphorization conditions in the early stage of converter blowing and increases the dephosphorization rate. However, this patent only improves the dephosphorization rate in the early stage of converter smelting and does not address dephosphorization throughout the entire smelting process.

[0007] Chinese Patent CN111363889A: A Method for High-Efficiency Phosphorus Removal in a Top-and-Bottom Combined-Blow Converter. This patent discloses a method for high-efficiency phosphorus removal in a top-and-bottom combined-blowing converter: some or all of the final slag from the previous furnace is retained in the furnace for use in the current furnace smelting; lime, lightly calcined dolomite, and ore are added in batches according to the target basicity; the bottom blowing process is controlled in stages, achieving efficient control of phosphorus fixation by the converter dephosphorizing agent. While this patent achieves high-efficiency phosphorus removal during the converter smelting process, it does not address post-furnace dephosphorization measures and is not particularly effective in reducing costs.

[0008] Addressing the challenge of deep dephosphorization of bearing steel, this patent innovatively designs a new dephosphorizing agent and devises new dephosphorization timing and operation methods during the smelting process, achieving efficient and low-cost dephosphorization of bearing steel and providing a new approach for enterprises to reduce costs and increase efficiency. Summary of the Invention

[0009] In order to overcome the shortcomings of the existing technology, the present invention provides a low-cost and high-efficiency dephosphorization method for bearing steel, which achieves high-efficiency dephosphorization not only during the converter smelting process, but also before and after the converter smelting.

[0010] Dephosphorization in converter smelting requires the production of high-basicity slag (basicity R = 3.0-6.0), necessitating the addition of large amounts of lime to meet smelting demands. The refining slag from bearing steel smelting also has high basicity (basicity R = 4.0-13.0). Effective recycling of this slag can significantly reduce the amount of lime and other slag materials required for converter smelting, thereby lowering smelting costs.

[0011] Therefore, the technical solution adopted in the low-cost and high-efficiency dephosphorization method for bearing steel of the present invention is as follows:

[0012] Before pouring molten iron into the converter, the remaining steel slag from the previous ladle, containing refining slag, is poured into the molten iron ladle. After pouring the molten iron containing the refining slag into the converter, blast furnace sinter or return ore is added. The amount of lime added in the early stage of converter smelting is reduced to 10-14 kg / t. To accommodate the changes in slag material, the oxygen lance position and oxygen flow rate are adjusted as follows during the early stage of converter smelting: during the initial blowing stage, the oxygen lance position is increased from 1300 mm to 1500 mm, and the ignition oxygen flow rate is increased to 7000-12000 m³ / t. 3 After 2-4 minutes, the oxygen lance position is controlled at 1300mm, and the oxygen supply flow rate is 6500-9000m³ / h. 3 At the end of the initial smelting stage, the oxygen lance is raised to 1600mm and held at the "zero position" for 20 seconds before entering the intermediate smelting stage. In the later stages of smelting, the amount of dolomite used in the furnace is reduced by 8-11 kg / t. During the initial decarburization stage, the oxygen lance position is maintained at 1600mm, and the oxygen supply flow rate is 10000 m³ / h. 3 / h, after 1 minute, manually increase the oxygen supply of the oxygen gun in steps, adjust the oxygen gun position to 1500mm, and the oxygen supply flow rate to 19000m³ / h. 3The oxygen flow rate is gradually reduced according to the slag and decarburization status. During the later stage of smelting, when the furnace is turned over, temperature sampling is carried out while 10-30% of the slag is poured out. The final steel composition meets the following requirements: P≤0.010%, C≥0.10%, and the final steel temperature is 1600~1650℃. After the converter tapping is completed, the oxygen lance position is controlled at 1200-1300mm for slag splashing and furnace protection. All the remaining steel slag in the furnace is left in the furnace for the next heat of steel. The final slag control requirements are: basicity R=2.0-3.5, FeO content 2-15%, MgO content 3-15%, P2O5 content ≤5%. After the converter tapping, in order to further reduce the phosphorus content in the steel, a dephosphorizing agent is used for slag washing and dephosphorization during the tapping process after the converter. The composition and ratio of the dephosphorizing agent are: BaCO3 35-55%; CaO 10-20%; CaF2 10-50%; Toner C 2-10%.

[0013] In the early stage of converter blowing, the oxygen lance position was increased from 1300mm to 1500mm, and the oxygen supply was also increased to 7000-12000mg / L. 3 / h, which is conducive to making full use of the low temperature conditions in the early stage of smelting, can quickly slag and provide appropriate FeO content to provide good thermodynamic conditions for efficient dephosphorization in the early stage.

[0014] During the later stages of smelting, the oxygen lance position was maintained at 1600mm during the initial decarburization phase, and the oxygen supply flow rate was 10000m³ / h. 3 / h can effectively prevent the slag from drying out again. Then the gun position is gradually lowered to below 1500mm, so that the slag is in a slightly dry state. The iron oxide balls and slag-forming materials work together to smelt, so as to adjust the state of the slag and dissolve more lime, thus effectively "bypassing" the mid-term splashing.

[0015] The above gun position and oxygen supply operation achieved better blowing effect: the splashing rate during the smelting process was reduced from 21% to 40% to below 12%; the carbon removal rate at the converter endpoint was increased from 72% to 93%, reducing the consumption of deoxidizer and slag, saving 0.42 kg of deoxidizer per ton of steel (equivalent to aluminum granules), and 4.25 kg of lime per ton of steel.

[0016] Preferably, before the molten iron is poured into the converter, a step of measuring the temperature of the molten iron is also included, wherein the temperature of the molten iron is ≥1250℃.

[0017] Preferably, the proportion of molten iron entering the furnace is 60-100%.

[0018] Preferably, the composition and proportion of the refining slag are: CaO 40-65%; SiO 20-25%; MgO 3-20%; Al2O3 20-55%; P2O 50-2%; FeO + Fe2O3 ≤ 1.5%.

[0019] Preferably, the method for slag washing and dephosphorization using a dephosphorizing agent during the tapping process after the converter is as follows: after tapping the steel from the converter, aluminum alloy, silicon alloy, manganese alloy, chromium alloy and carbon powder are added in sequence, followed by bottom blowing with large argon gas for 1 minute, and then 40-100 kg of dephosphorizing agent is added in small batches of 2-4 times; after tapping, the steel is stirred with large argon gas for 1-3 minutes, and samples are taken to analyze the phosphorus content of the molten steel during the large argon gas period. After the process, the phosphorus content in the steel is stably controlled to ≤0.007%.

[0020] Preferably, if the P content in the steel is not below 0.007% after slag washing, the flow rate of bottom-blown argon gas in the ladle is adjusted to the maximum, the pressure of bottom-blown argon gas is ≥1.0MPa, and 10-20kg of dephosphorizing agent is added to the top slag and strongly stirred for 1-2 minutes.

[0021] Preferably, the dephosphorizing agent is in powder form with a particle size of 0.01-2 mm.

[0022] Preferably, the steel tapping process in the later stages of smelting employs a double-layer slag-blocking system consisting of a sliding plate and a slag-blocking cone to prevent slag from falling during tapping.

[0023] The advantages and positive effects of this invention are as follows:

[0024] In the early stage of converter smelting, the use of residual steel slag from the pre-processing ladle, which includes recycled high-basicity refining slag, reduces the amount of lime added by 50%, lowering the raw material cost of the converter. The added high-basicity refining slag contains FeO+Fe2O3≤1.5%. Adding blast furnace sinter or return ore in the early stage of converter smelting not only meets the initial dephosphorization requirements but also reduces Fe oxidation in the molten steel, reduces iron loss, and increases metal recovery. This achieves low-cost dephosphorization smelting in the early stage of converter smelting, with a dephosphorization rate ≥80%. Because the refining slag contains 3-20% MgO, the amount of dolomite used in the converter smelting process can be reduced, further lowering smelting costs. An innovative dephosphorizing agent for washing slag after the furnace is designed to achieve deep dephosphorization after the converter. Using this method, the final P content in the converter can be stably controlled to ≤0.010%, and the converter smelting cycle can be shortened by 3-6 minutes, achieving the goal of low-cost and high-efficiency dephosphorization. Detailed Implementation

[0025] To better understand the present invention, specific details are provided below with reference to embodiments.

[0026] Example 1

[0027] The low-cost and high-efficiency dephosphorization method for bearing steel described in this embodiment was tested in a 100-ton converter at a steel company, and the process for producing one batch of bearing steel GCr15 is as follows:

[0028] (1) The composition and ratio of the refining slag recycled in the converter are as follows: CaO: 50%; SiO2: 11%; MgO: 4.6%; Al2O3: 28%; P2O5: 0.6%; FeO+Fe2O3: 0.7%. 2.3 tons of the refining slag with the above composition and ratio were poured into the molten iron ladle. The temperature of the molten iron was measured to be 1280℃ before the ladle was hoisted into the furnace, and the proportion of molten iron entering the furnace was 80%.

[0029] (2) After pouring the molten iron containing recycled high-basicity refining slag into the converter, add 2.9 kg / t of blast furnace sinter or return ore. The lime addition during the early stage of converter smelting is 12 kg / t. To accommodate the changes in slag material, the oxygen lance position during the initial blowing stage is increased from 1300 mm to 1500 mm, and the oxygen flow rate during ignition is increased to 9000 m³ / h. 3 / h; after 3 minutes, the gun position is controlled at 1300mm, and the oxygen supply flow rate is 7000m³ / h. 3 / h. At the end of the initial stage, the lance is raised to 1600mm and held at the "zero position" for 20 seconds before entering the intermediate decarburization stage. The dephosphorization rate in the early stage of converter smelting is 83%.

[0030] (3) In the middle and late stages of smelting: the amount of dolomite used in the furnace is reduced by 10.6 kg / t, thus reducing smelting costs; the lance position is maintained at 1600 mm and the oxygen flow rate is 10000 m³ / t during the initial stage of decarburization. 3 / h; After 1 minute, manually increase the oxygen supply of the oxygen lance in steps, adjust the blowing lance position to 1500mm, and the oxygen supply flow rate to 19000m³ / h. 3 The oxygen flow rate was initially set at 1 / h, and then gradually reduced based on the slag and decarburization status. During the later stages of smelting, when the furnace was being turned over, temperature samples were taken while 15% of the slag was being poured out. The final steel composition at the blowing endpoint was: P 0.009%, C 0.11%, and the final steel temperature was 1630℃. A double-layer slag-blocking system, consisting of a sliding plate and a slag-blocking cone, was used for tapping to prevent slag from falling during tapping.

[0031] (4) After the converter tapping is completed, the oxygen lance position is controlled at 1260mm for slag splashing to protect the furnace. All the remaining steel slag in the furnace is left in the furnace for the smelting of the next heat of steel, thereby improving the steel slag recovery rate. Final slag composition: basicity R=2.6, FeO content 10%, MgO content 6%, P2O5 content 2.3%.

[0032] (5) The final P content of the converter is controlled at 0.009%, and the converter smelting cycle can be shortened by 5 minutes, so as to achieve the purpose of low-cost and high-efficiency dephosphorization.

[0033] (6) The composition and formulation of the dephosphorizing agent used in this furnace are as follows: BaCO3 40%; CaO 16%; CaF2 30%; carbon powder C 6%. The dephosphorizing agent is in powder form with a particle size of 0.02-1.8mm.

[0034] (7) After the steel is tapped from the converter, aluminum alloy, silicon alloy, manganese alloy, chromium alloy and carbon powder are added in sequence. After 1 minute of bottom blowing with large argon gas, 60 kg of dephosphorizing agent is added in 3 small batches.

[0035] (8) After tapping, stir with argon gas for 2 minutes. During the argon gas process, take a sample to analyze the phosphorus content of the molten steel. After the process, control the phosphorus content in the steel to 0.006%.

[0036] Example 2

[0037] The low-cost and efficient dephosphorization method for bearing steel described in this embodiment was tested in a 120-ton converter at a steel company, and the process for producing one batch of bearing steel GCr15 is as follows:

[0038] (1) The composition and ratio of the refining slag recycled by the converter are: CaO: 65%; SiO2: 25%; MgO: 3%; Al2O3: 20%; FeO+Fe2O3: 1.5%. 1.8 tons of the refining slag with the above composition and ratio are poured into the molten iron ladle. The temperature of the molten iron is measured to be 1300℃ before the ladle is hoisted into the furnace, and the proportion of molten iron entering the furnace is 100%.

[0039] (2) After pouring the molten iron containing recycled high-basicity refining slag into the converter, add 3.1 kg / t of blast furnace sinter or return ore. The lime addition during the early stage of converter smelting is 14 kg / t. To accommodate the changes in slag material, the oxygen lance position is raised to 1500 mm during the initial blowing stage, and the oxygen flow rate is increased to 12000 m³ / h. 3 / h; after 4 minutes, the gun position is controlled at 1300mm, and the oxygen supply flow rate is 9000m³ / h. 3 / h. At the end of the initial stage, the lance is raised to 1600mm and held at the "zero position" for 20 seconds before entering the intermediate decarburization stage. The dephosphorization rate in the early stage of converter smelting is 84%.

[0040] (3) In the middle and late stages of smelting: the amount of dolomite used in the furnace is reduced by 11 kg / t, reducing smelting costs; the lance position is maintained at 1600 mm and the oxygen flow rate is 10000 m³ / t during the initial stage of decarburization. 3 / h; After 1 minute, manually increase the oxygen supply of the oxygen lance in steps, adjust the blowing lance position to 1500mm, and the oxygen supply flow rate to 19000m³ / h. 3 The oxygen flow rate was initially set at 0.010% per hour, and then gradually reduced based on the slag and decarburization status. During the later stages of smelting, when the furnace was being turned over, temperature samples were taken while 30% of the slag was being removed. The final steel composition at the blowing endpoint was: P 0.010%, C 0.1%, and the final steel temperature was 1650℃. A double-layer slag-blocking system, consisting of a sliding plate and a slag-blocking cone, was used for tapping to prevent slag from falling during tapping.

[0041] (4) After the converter tapping is completed, the oxygen lance position is controlled at 1300mm for slag splashing to protect the furnace. All the remaining steel slag in the furnace is left in the furnace for the smelting of the next heat of steel, thereby improving the steel slag recovery rate. Final slag composition: basicity R=3.5, FeO content 15%, MgO content 3%, P2O5 content 5%.

[0042] (5) The final P content of the converter is controlled at 0.008%, and the converter smelting cycle can be shortened by 6 minutes, so as to achieve the purpose of low-cost and high-efficiency dephosphorization.

[0043] (6) The composition of the new dephosphorizing agent used in this furnace is as follows: BaCO3 35%; CaO 20%; CaF 250%; carbon powder C 2%. The dephosphorizing agent is in powder form with a particle size of 0.03-1.5mm.

[0044] (7) After the steel is tapped from the converter, aluminum alloy, silicon alloy, manganese alloy, chromium alloy and carbon powder are added in sequence. After 1 minute of bottom blowing with large argon gas, 100 kg of dephosphorizing agent is added in 4 small batches.

[0045] (8) After tapping, stir with argon gas for 3 minutes. During the argon gas process, take a sample to analyze the phosphorus content of the molten steel. After the process, control the phosphorus content in the steel to 0.005%.

[0046] Example 3

[0047] The low-cost and efficient dephosphorization method for bearing steel described in this embodiment was tested in a trial run of one heat of GCr15 bearing steel in an 80-ton converter at a steel company. The process is as follows:

[0048] (1) The composition and ratio of the refining slag recycled by the converter are: CaO: 40%; MgO: 20%; Al2O3: 55%; P2O5: 2%; FeO+Fe2O3: 0.6%. Two tons of the above-mentioned refining slag with the above composition and ratio are poured into the molten iron ladle. The temperature of the molten iron is measured to be 1250℃ before the ladle is hoisted into the furnace, and the proportion of molten iron entering the furnace is 60%.

[0049] (2) After pouring the molten iron containing recycled high-basicity refining slag into the converter, add 2.6 kg / t of blast furnace sinter or return ore. The lime addition during the early stage of converter smelting is 10 kg / t. To accommodate the changes in slag material, the oxygen lance position is raised to 1500 mm during the initial blowing stage, and the oxygen flow rate is increased to 7000 m³ / t. 3 / h; after 2 minutes, the gun position is controlled at 1300mm, and the oxygen supply flow rate is 6500m³ / h. 3 / h. At the end of the initial stage, the lance is raised to 1600mm and held at the "zero position" for 20 seconds before entering the intermediate decarburization stage. The dephosphorization rate in the early stage of converter smelting is 82%.

[0050] (3) In the middle and late stages of smelting: the amount of dolomite used in the furnace is reduced by 8 kg / t to lower smelting costs; the lance position is maintained at 1600 mm and the oxygen flow rate is 10000 m³ / t during the initial stage of decarburization. 3 / h; After 1 minute, manually increase the oxygen supply of the oxygen lance in steps, adjust the blowing lance position to 1500mm, and the oxygen supply flow rate to 19000m³ / h. 3 The oxygen flow rate was initially set at 10% per hour, and then gradually reduced based on the slag and decarburization status. During the final stage of smelting, when the furnace was being turned over, temperature samples were taken while 10% of the slag was being removed. The final steel composition was: P 0.010%, C 0.12%, and the final steel temperature was 1600℃. A double-layer slag barrier, consisting of a sliding plate and a slag-blocking cone, was used for tapping to prevent slag from falling during tapping.

[0051] (4) After the converter tapping is completed, the oxygen lance position is controlled at 1200mm for slag splashing to protect the furnace. All the remaining steel slag in the furnace is left in the furnace for the smelting of the next heat of steel, thereby improving the steel slag recovery rate. Final slag composition: basicity R=2.0, FeO content 2%, MgO content 15%, P2O5 content 4%.

[0052] (5) The final P content of the converter is controlled at 0.009%, and the converter smelting cycle can be shortened by 3 minutes, so as to achieve the purpose of low-cost and high-efficiency dephosphorization.

[0053] (6) The composition of the new dephosphorizing agent used in this furnace is as follows: BaCO3 55%; CaO 10%; CaF2 10%; carbon powder C 10%. The dephosphorizing agent is in powder form with a particle size of 0.01-2mm.

[0054] (7) After the steel is tapped from the converter, aluminum alloy, silicon alloy, manganese alloy, chromium alloy and carbon powder are added in sequence. After 1 minute of bottom blowing with large argon gas, 40 kg of dephosphorizing agent is added in two small batches.

[0055] (8) After tapping, stir with a large amount of argon gas for 1 minute. During the argon gas process, take a sample to analyze the phosphorus content of the molten steel. After the process, control the phosphorus content in the steel to 0.0075%. Adjust the bottom blowing argon gas flow rate of the ladle to the maximum (bottom blowing argon gas pressure ≥ 1.0 MPa). At the same time, add 10-20 kg of dephosphorizing agent to the top slag and stir strongly for 1-2 minutes. After the process, analyze again. The phosphorus content in the steel should be controlled to 0.007%.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for low cost and efficient dephosphorization of bearing steel, characterized in that, The method is: Before the molten iron is poured into the converter, the pre-sequencing ladle slag containing refining slag is poured into the ladle in advance; after the molten iron containing the refining slag is poured into the converter, the sintered ore or return ore of the blast furnace is added, and the amount of lime added in the early stage of the converter smelting is reduced to 10-14 kg / t; in order to match the adjustment and change of the slag material, the oxygen lance position and the oxygen flow in the early stage of the converter smelting are adjusted and changed as follows: the oxygen lance position is raised from the original 1300 mm to 1500 mm in the blowing stage, the ignition oxygen supply flow is increased to 7000-12000 m3 / h, the oxygen lance position is controlled at 1300 mm after 2-4 minutes, the oxygen supply flow is 6500-9000 m3 / h, the oxygen lance is raised to 1600 mm at the end of the early stage of smelting, and is kept in the "zero position" state for 20 seconds, and then enters the middle stage of smelting; in the middle and late stages of smelting, the amount of dolomite added into the furnace is reduced by 8-11 kg / t, the oxygen lance position is kept at 1600 mm in the initial stage of decarburization, the oxygen supply flow is 10000 m3 / h, the oxygen supply amount of the oxygen lance is increased manually in steps after 1 minute, the oxygen lance position is adjusted to 1500 mm, the oxygen supply flow is 19000 m3 / h, and then the oxygen blowing flow is gradually reduced according to the slag and decarburization; the temperature is measured and the sample is taken while 10-30% of the slag is poured out in the late stage of smelting, the composition of the molten steel at the end of blowing meets: P≤0.010%, C≥0.10%, and the temperature of the molten steel at the end of blowing is 1600-1650℃; after the converter tapping is completed, the oxygen lance position is controlled at 1200-1300 mm for slag splashing and converter protection, and the remaining steel slag in the furnace is kept in the furnace for the smelting of the next batch of steel, and the final slag control requirements are: basicity R=2.0-3.5, FeO content 2-15%, MgO content 3-15%, and P2O5 content ≤5%; after the converter tapping, in order to further reduce the phosphorus content in the steel, a dephosphorizing agent is used for slag washing and dephosphorization in the post-converter tapping process, and the composition and ratio of the dephosphorizing agent are: BaCO3 35-55%; CaO 10-20%; CaF2 10-50%; carbon powder C 2-10%; The composition and ratio of the refining slag are: CaO 40-65%; SiO2 0-25%; MgO 3-20%; Al2O3 20-55%; P2O5 0-2%; FeO+Fe2O3 ≤1.5%; The method for using a dephosphorizing agent for slag washing and dephosphorization in the post-converter tapping process is: after the aluminum alloy, silicon alloy, manganese alloy, chromium alloy and carbon powder are added in sequence in the post-converter tapping, 40-100 kg of the dephosphorizing agent is added after 1 minute of large argon bottom blowing, and is added in small batches for 2-4 times; after the tapping is completed, the molten steel is stirred for 1-3 minutes under large argon, the phosphorus content in the molten steel is analyzed during the large argon period, and the phosphorus content in the steel is stably controlled to be ≤0.007% after the end; If the P content in the steel after slag washing does not reach below 0.007%, the bottom argon flow of the ladle is adjusted to the maximum, the bottom argon pressure is ≥1.0 MPa, 10-20 kg of the dephosphorizing agent is added in the top slag, and strong stirring is performed for 1-2 minutes.

2. A process for low cost and efficient dephosphorization of a bearing steel as claimed in claim 1, wherein: Before the molten iron is poured into the converter, a step of measuring the temperature of the molten iron is further included, and the temperature of the molten iron is greater than or equal to 1250 DEG C.

3. A process for low cost and efficient dephosphorization of a bearing steel as claimed in claim 1, wherein: The molten iron accounts for 60-100% of the furnace.

4. The method of low cost and efficient dephosphorization of bearing steel according to claim 1, characterized in that: The dephosphorizing agent is in powder form, and the particle size is 0.01-2 mm.

5. The method of low cost and efficient dephosphorization of bearing steel according to claim 1, characterized in that: In the tapping process in the later stage of smelting, a double-layer slag dam is used to prevent slag from flowing down.