CN114540568B - Smelting method for improving scrap steel ratio - Google Patents
Smelting method for improving scrap steel ratio Download PDFInfo
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- CN114540568B CN114540568B CN202210441000.XA CN202210441000A CN114540568B CN 114540568 B CN114540568 B CN 114540568B CN 202210441000 A CN202210441000 A CN 202210441000A CN 114540568 B CN114540568 B CN 114540568B
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/30—Regulating or controlling the blowing
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/56—Manufacture of steel by other methods
- C21C5/562—Manufacture of steel by other methods starting from scrap
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/072—Treatment with gases
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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Abstract
The invention discloses a smelting method for improving scrap steel ratio, which belongs to the field of ferrous metallurgy and comprises the following steps: s1, blast furnace molten iron; s2, adding a steel bar pressing block into the ladle; s3, converter charging: keeping the high-heat slag after the slag splashing of the previous furnace for 1.0-2.0 t, and adding 22-30 t of scrap steel into the converter; s4, converter blowing: controlling the oxygen pressure of the oxygen lance to be 0.78-0.86 Mpa; the gun position adopts a low, high and low position mode; s5, alloying in tapping: tapping time is controlled to be 150-350 s, and ladle off-line time is less than or equal to 60 min; soft argon blowing is carried out after the furnace; and S6, after the argon blowing is finished, hoisting the ladle to LF refining treatment or hoisting to a continuous casting machine for casting. The invention overcomes the problems of scrap steel preheating, heating agent addition and the like in the prior art, has safe and convenient operation, ensures that the scrap steel accounts for more than 30 percent, realizes energy conservation and emission reduction, improves the yield of molten steel, and obtains better social benefit and economic benefit.
Description
Technical Field
The invention belongs to the field of ferrous metallurgy, relates to a converter steelmaking process, and particularly relates to a smelting method for improving a scrap ratio by process improvement without preheating scrap steel and adding a heating agent.
Background
Compared with the production of steel by adopting ores and coking coals, the steel making by using the scrap steel can greatly save energy and reduce emission, so that the improvement of the scrap steel ratio in the molten steel smelting can greatly reduce environmental pollution and comprehensive energy consumption. The environmental protection policy of China is tightened increasingly, the output of sinter and blast furnaces is strictly limited, the steel output can be increased and the cost can be reduced by improving the scrap steel ratio under the condition of lacking molten iron, and meanwhile, along with the increase of the steel accumulation and the scrap steel resource of China, the price advantage of the scrap steel is prominent, the scrap steel ratio is improved and the molten steel cost can be reduced.
The bottleneck technique for improving the scrap ratio is the compensation of the heat of the converter system. In the prior art for improving the steel scrap ratio, the physical heat of the steel scrap is improved in a steel scrap preheating mode to improve the steel scrap ratio, for example, in the prior art, a smelting method for improving the steel scrap ratio of a converter is disclosed as CN111254250A, oxygen and coke oven gas are needed to preheat the steel scrap in the converter for 3-5 min, the technology needs to be implemented by additionally arranging equipment such as a coke oven gas conveying pipeline, a preheating oxygen lance and a control system thereof, the preheating oxygen lance is complex in structure, high in using difficulty and high in risk coefficient, meanwhile, the preheating for 3-5 min reduces the working efficiency of the converter, increases the production organization difficulty, and increases the energy consumption and the production cost by preheating the coke oven gas; besides the method, a technology for improving the scrap ratio by adding a heat generating agent such as coke or silicon carbide and the like into a converter to improve the chemical heat of molten iron is adopted, and the technology has the problems of increased energy consumption, increased carbon emission, high iron loss, increased steel making cost and the like.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a smelting method for improving the scrap steel ratio by only improving the process without preheating the scrap steel and adding a heating agent.
The invention is realized in such a way that a smelting method for improving the ratio of scrap steel is characterized by comprising the following steps:
s1, blast furnace molten iron: the molten iron is used as a main raw material for converter steelmaking, physical heat and chemical heat are provided for converter smelting, the tapping temperature is more than or equal to 1500 ℃, and the molten iron comprises the following components: 4.0% or more, Si: 0.40 to 0.60%, Mn: 0.30-0.60%, P: 0.130% or less, S: less than or equal to 0.035%;
s2, adding a steel bar pressing block into the ladle: adding a steel bar pressing block into the ladle before adding molten iron; the size of the steel bar pressing block is required to be less than or equal to 1800mm in length, less than or equal to 800mm in width and thickness, and the diameter of the steel bar is required to be 6-30 mm; controlling the adding amount of the steel bar pressing block to be 10-15 t, standing for 10-12 min after the steel bar pressing block is added, and then adding molten iron, wherein the adding amount of the molten iron is 80-85 t; after the molten iron is added into the ladle, the standing time is more than or equal to 10min, the added steel bar pressing block is ensured to be completely molten, and the temperature of the molten iron is ensured to be more than or equal to 1250 ℃;
s3, converter charging: keeping high-heat slag with the temperature of 1300 ℃ or higher after slag splashing from the previous furnace for 1.0-2.0 t, adding 22-30 t of scrap steel into the converter by using a scrap steel hopper, wherein the single piece of scrap steel is not more than 1t, the adding amount of slag steel in the scrap steel is not more than 5% of the amount of the scrap steel, adding 0-3 t of pig iron according to the conditions of molten iron and the scrap steel to improve the chemical heat of the molten steel, adding the molten iron into the converter, and blowing;
s4, converter blowing: controlling the oxygen pressure of an oxygen lance for converter blowing to be 0.78-0.86 Mpa; activating a molten pool, ensuring that scrap steel is completely melted in the blowing process, adopting a low-position mode, a high-position mode and a low-position mode for a gun position, controlling the low position to be 1650-1900 mm by an oxygen gun position at the early stage, and quickly heating; the middle oxygen lance position control high position is 1900 mm-2200 mm, and the later oxygen lance position control low position is 1400 mm-1550 mm; adding stamping excess scrap steel with the diameter less than or equal to 60mm and the thickness of 4-10 mm through an overhead bunker in the blowing process, wherein the stamping excess scrap steel is required to have a smooth surface without hanging thorns; adding 0.8-2.4 t of stamping excess scrap steel, and strictly adding the scrap steel after oxygen supply and blowing for 600 s; the smelting end point target C is more than or equal to 0.06 percent, and the temperature is more than or equal to 1580 ℃;
s5, alloying in tapping: tapping time is controlled to be 150-350 s, and steel ladle off-line time is less than or equal to 60 min; adding the steel bar heads and/or stamping excess scrap steel and scrap steel along with the alloy again in the tapping process, wherein the total addition amount is 0.3-1 t, slag is strictly forbidden in the tapping process, and the thickness of a slag layer is required to be less than or equal to 30 mm; soft argon blowing is carried out after the furnace, the liquid level is required to slightly surge, the molten steel is not exposed, and the argon blowing time is more than or equal to 5 min;
and S6, after argon blowing is finished, hoisting the ladle to an LF furnace for refining treatment or hoisting to a continuous casting machine for casting.
Preferably, the tapping temperature in the step S1 is greater than or equal to 1550 ℃, and the steel bar heads and/or the stamping excess scrap steel are added into the torpedo ladle for 4-7 t in the tapping process.
Preferably, in the step S6, in the process of hoisting the steel ladle to an LF furnace for refining treatment, 0.5-2 t of stamping remainder scrap steel is added into the steel ladle, and then the temperature of molten steel is increased in an electric heating mode.
The invention has the beneficial effects that: by adopting the technical scheme, waste steel preheating facilities are not added, the increase of equipment investment and energy consumption is avoided, and the increase of carbon emission and cost caused by adding heating agents such as coke, silicon carbide and the like into the converter is avoided. The smelting process for improving the scrap steel ratio is feasible, overcomes the problems of scrap steel preheating, heating agent addition and the like in the prior art, and is safe and convenient to operate. By adopting the process, the scrap steel proportion can reach more than 30 percent, the high scrap steel proportion molten steel smelting is realized only through process change without adopting scrap steel preheating and adding a heating agent, meanwhile, the energy conservation and emission reduction in the molten steel smelting process are realized, the molten steel yield is improved, and better social benefit and economic benefit are obtained.
Drawings
FIG. 1 is a flow chart of a method implementation of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, a smelting method for increasing a scrap ratio includes the following steps: s1, blast furnace molten iron: the molten iron is used as a main raw material for converter steelmaking, physical heat and chemical heat are provided for converter smelting, the tapping temperature is more than or equal to 1500 ℃, and the molten iron comprises the following components: c: 4.0% or more, Si: 0.40-0.60%, Mn: 0.30-0.60%, P: 0.130% or less, S: less than or equal to 0.035%; the control of the components of the molten iron, particularly the Si content, is required to be 0.40-0.60%, and the purpose is to improve the chemical heat of the molten iron on the premise of ensuring the smooth operation of a blast furnace;
s2, adding a steel bar pressing block into the ladle: adding a steel bar pressing block into the ladle before adding molten iron; the dimension and the length of the reinforcing steel bar pressing block are less than or equal to 1800mm, the width and the thickness of the reinforcing steel bar pressing block are less than or equal to 800mm, and the diameter of the reinforcing steel bar is required to be 6-30 mm; the steel bar pressing block is added because the steel bar pressing block has certain framework supporting function and is not dense, the contact area with molten iron is large, and the melting is convenient. If small pieces of scrap steel are adopted, the scrap steel is easy to stick to the ladle bottom and is not suitable for melting; large pieces of scrap steel are adopted, and the scrap steel is not completely melted; light and thin scrap steel is adopted, the loading amount of the scrap steel is small, and the temperature drop is large; the size requirement of the steel bar pressing block is to achieve the purposes of convenient loading of the steel bar pressing block into an iron ladle and rapid melting. Controlling the adding amount of the steel bar pressing block to be 10-15 t, standing for 10-12 min after the steel bar pressing block is added, and then adding molten iron, so that water on the scrap steel is evaporated to prevent the water from being brought into the steel to influence the quality of steel products, and the scrap steel is preliminarily preheated; adding 80-85 t of molten iron, pouring small flows in the molten iron adding process, adding normal flows after a molten pool is stable, increasing the flow velocity of the molten iron in the molten iron adding process under the condition of ensuring safety, and ensuring that the impact of the molten iron on scrap steel is beneficial to melting the scrap steel; after the molten iron is added into the ladle, the standing time is not less than 10min, the added steel bar pressing block is ensured to be completely molten, and the temperature of the molten iron is ensured to be more than or equal to 1250 ℃; the physical heat and the kinetic energy of the molten iron are fully utilized, and the adding amount of the scrap steel is increased under the condition of not increasing scrap steel preheating facilities;
s3, converter charging: keeping high-heat slag with the temperature of 1300 ℃ or higher after the slag is splashed by the previous furnace for 1.0-2.0 t, wherein the purpose of keeping the high-heat slag is to reduce the consumption of slag making materials so as to reduce the heat loss caused by the slag making materials, and the high-heat slag can preheat the waste steel added into the converter so as to accelerate the melting speed of the waste steel and facilitate smelting; 22-30 t of scrap steel is added into the converter by using a scrap steel hopper, the scrap steel is reasonably matched, a single piece of scrap steel is not more than 1t, the addition amount of slag steel in the scrap steel is not more than 5% of the amount of the scrap steel, and 0-3 t of pig iron can be added according to the conditions of molten iron and the scrap steel added into the converter, so that the chemical heat of the molten steel can be adjusted; continuously adding molten iron into the converter for converting;
s4, converter blowing: controlling the oxygen pressure of an oxygen lance for converter blowing to be 0.78-0.86 Mpa, promoting the activity of a molten pool, ensuring the complete melting of scrap steel in the blowing process, adopting a low position mode, a high position mode and a low position mode at the lance position, controlling the low position to be 1650 mm-1900 mm for rapid temperature rise at the early stage, controlling the high position to be 1900 mm-2200 mm at the middle stage, and controlling the low position to be 1400 mm-1550 mm at the later stage; adding stamping excess scrap steel with the diameter less than or equal to 60mm and the thickness of 4-10 mm through an overhead bunker in the blowing process, wherein the stamping excess scrap steel requires a smooth surface without hanging thorns, and the stamping excess scrap steel requires the size to facilitate conveying of the overhead bunker and prevent material blockage in the discharging process; the adding amount of stamping excess scrap steel is 0.8-2.4 t; strictly adding the waste steel after oxygen supply blowing for 600s, wherein the waste steel is in the later stage of blowing, and the added waste steel is prevented from being incompletely melted; the smelting end point target C is more than or equal to 0.06 percent, and the temperature is more than or equal to 1580 ℃;
s5, alloying in tapping: the tapping time is controlled to be 150-350 s, the temperature of molten steel is reduced too much due to too long tapping time, and tapping slag is easily generated due to too short tapping time. The off-line time of the steel ladle is less than or equal to 60 min; adding the steel bar heads and/or stamping excess scrap steel along with the alloy again in the tapping process, wherein the total addition amount is 0.3-1 t; slag is strictly forbidden to be discharged in the tapping process, and the thickness of a slag layer is required to be less than or equal to 30 mm; soft argon blowing is carried out after the furnace, the liquid level is required to slightly surge, the molten steel is not exposed, and the argon blowing time is more than or equal to 5 min;
and S6, after argon blowing is finished, hoisting the ladle to an LF furnace for refining treatment or hoisting to a continuous casting machine for casting.
When the tapping temperature is higher than or equal to 1550 ℃ in the step S1, adding the steel bar heads and/or stamping residual scrap steel into the torpedo ladle for 4-7 t in the tapping process; adding a steel bar head and/or stamping excess scrap steel into the torpedo tank along with the flow of molten iron in the process that the molten iron of the blast furnace flows into the torpedo tank through the iron tapping channel; conveying the blast furnace molten iron to a steelmaking area through a torpedo ladle, and pouring the molten iron into a ladle at a ladle pouring station, wherein 2.5-3 ladles of molten iron can be poured into one torpedo ladle;
in the process of hoisting the steel ladle to an LF furnace for refining treatment, 0.5-2 t of stamping excess scrap steel can be added into the steel ladle, and then the temperature is increased by using an electric heating mode, so that the steel yield is increased. When the steel benefits in the market are good, and the steel yield can be remarkably increased by improving the steel yield, stamping excess scrap steel can be added in the refining process, and the molten steel temperature is improved by an electric heating mode, so that the steel yield and the benefit can be increased. Because the harmful elements such as phosphorus, sulfur and the like in the scrap steel are higher, the adding amount of the scrap steel is not suitable to be too high during refining.
Therefore, the purpose of improving the scrap steel ratio is realized only by process improvement without adopting scrap steel preheating and adding a heating agent. To illustrate the effects, the following examples are given.
Example 1: a smelting method for improving the ratio of scrap steel comprises the following steps:
s1, blast furnace molten iron: tapping temperature: 1520 ℃, molten iron components: c: 4.21%, Si: 0.41%, Mn: 0.42%, P: 0.127%, S: 0.031%;
s2, adding a steel bar pressing block into the ladle: adding a steel bar pressing block into the ladle for 12.2t, and standing for 11.5min after the steel bar pressing block is added; adding 83.6t of molten iron, and keeping the temperature of molten iron at 1378 ℃; adding molten iron into a ladle, and standing for 12min at 1274 ℃;
s3, loading in a converter: adding common steel scrap with the type of heavy steel scrap and medium steel scrap with the slag remaining amount of 1.1t into the furnace, adding 27.4t of pig iron and adding 2t of pig iron;
s4, converter blowing: the control conditions of the converter blowing process are shown in table 1;
table 1 shows the control of the converter blowing process in example 1
End-point composition: 0.07 percent of C, and the end point temperature is 1621 ℃;
s5, alloying of the steel: carrying out off-line on the steel ladle for 44min for normal ladle, tapping for 247s, adding a steel bar head for 0.85t in the tapping process, and carrying out soft blowing for 8 min;
and S6, after argon blowing is finished, hoisting the ladle to a continuous casting machine for pouring.
In the embodiment, 41.65t of scrap steel, 83.6t of molten iron, 2.0t of pig iron and 32.73 percent of scrap steel are added together, so that the high scrap steel ratio smelting is realized.
Example 2: a smelting method for improving the scrap steel ratio comprises the following steps:
s1, blast furnace molten iron: tapping temperature: 1530 ℃, molten iron composition: c: 4.78%, Si: 0.58%, Mn: 0.38%, P: 0.121%, S: 0.025 percent;
s2, adding a steel bar pressing block into the ladle: adding a steel bar pressing block into the ladle for 14.5t, and standing for 11min after the steel bar pressing block is added; adding 80.5t of molten iron, wherein the temperature of the molten iron is 1385 ℃; adding molten iron into the ladle, and standing for 11.5min at 1258 ℃;
s3, loading in a converter: adding common steel scrap with the type of heavy steel scrap and medium steel scrap with the slag amount of 1.8t into the furnace, wherein the adding amount is 29.7t, and no pig iron is added;
s4, converter blowing: the control conditions of the converter blowing process are shown in table 2;
table 2 shows the control of the converter blowing process in example 2
End-point composition: 0.06 percent of C and 1600 percent of end point temperature;
s5, alloying in tapping: carrying out off-line on the steel ladle for a normal ladle within 48min, wherein the tapping time is 305s, and the total amount of the steel bar heads and the stamping excess scrap steel added in the tapping process is 0.55 t; soft blowing time 6.5 min;
and S6, hoisting the ladle to LF for refining treatment after argon blowing is finished.
In the embodiment, 46.75t of scrap steel, 80.5t of molten iron, 0t of pig iron and 36.74 percent of scrap steel are added together, so that the high scrap steel ratio smelting is realized.
Example 3: a smelting method for improving the ratio of scrap steel comprises the following steps:
s1, blast furnace molten iron: tapping temperature: 1530 ℃, molten iron composition: c: 4.71%, Si: 0.51%, Mn: 0.44%, P: 0.117%, S: 0.026%.
S2, adding a steel bar pressing block into the ladle: adding a steel bar pressing block into the ladle for 14.7t, and standing for 10.5min after the steel bar pressing block is added; adding 82.0t of molten iron, and keeping the temperature of molten iron at 1398 ℃; adding molten iron into a ladle, and standing for 12.5min at 1260 ℃;
s3, loading in a converter: adding common steel scrap with the type of heavy steel scrap and medium steel scrap with the slag remaining amount of 1.5t into the furnace, adding 27.8t of pig iron and 2.2t of pig iron;
s4, converter blowing: the control conditions of the converter blowing process are shown in the table 3;
table 3 shows the control of the converter blowing process in example 3
End-point composition: 0.08 percent of C and the end point temperature of 1614 ℃;
s5, alloying in tapping: carrying out off-line on the steel ladle for 54min for normal ladle, tapping for 195s, adding 0.65t of stamping excess scrap steel, and carrying out soft blowing for 8.5 min;
and S6, after argon blowing is finished, hoisting the ladle to a continuous casting machine for pouring.
In the embodiment, 44.45t of scrap steel, 82.0t of molten iron, 2.2t of pig iron and 34.55 percent of scrap steel are added together, so that the high-scrap-ratio smelting is realized.
Example 4: a smelting method for improving the ratio of scrap steel comprises the following steps:
s1, blast furnace molten iron: tapping temperature: 1560 ℃, molten iron components: c: 4.85%, Si: 0.52%, Mn: 0.36%, P: 0.123%, S: 0.027%; 6.2t of steel bar head waste steel is added into the torpedo tank, and 2.3t of waste steel is added into each furnace.
S2, adding a steel bar pressing block into the ladle: adding 13.7t of steel bar pressing blocks into the ladle, and standing for 10.5min after the steel bar pressing blocks are added; adding 80.3t of molten iron; the temperature of molten iron is 1365 ℃; adding molten iron into the ladle, and standing for 11.5min at 1255 ℃;
s3, converter charging: adding common steel scrap with the type of heavy steel scrap and medium steel scrap with the slag amount of 1.7t into the furnace, wherein the adding amount is 26.9t, and no pig iron is added;
s4, converter blowing: the control conditions of the converter blowing process are shown in Table 4;
table 4 shows the control of the converter blowing process in example 4
End-point composition: 0.06 percent of C and the end point temperature of 1588 ℃;
s5, alloying in tapping: carrying out off-line on the steel ladle for a normal ladle within 43min, tapping for 284s, and adding steel bar head scrap steel for 0.65 t; after soft blowing for 5.5 minutes, hoisting to LF refining treatment;
and S6, hoisting the ladle to LF for refining treatment after argon blowing, adding stamping excess scrap steel for 0.8t in the treatment process, increasing the refining power supply time for 4.5min, and hoisting to continuous casting for casting after treatment.
In the embodiment, 46.75t of scrap steel, 80.3t of molten iron, 0t of pig iron and 37.47% of scrap steel are added together, so that the high scrap steel ratio smelting is realized.
The embodiment proves that the smelting process for improving the scrap steel ratio is feasible, the problems of scrap steel preheating, heating agent addition and the like in the prior art are solved, and the operation is safe and convenient. By adopting the process, the proportion of the scrap steel can reach more than 30 percent, the scrap steel is not preheated, a heating agent is not added, the aim of improving the proportion of the scrap steel is realized only through process improvement, energy conservation and emission reduction in the molten steel smelting process are realized, the yield of the molten steel is improved, and better social benefit and economic benefit are obtained.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (3)
1. A smelting method for improving the ratio of scrap steel is characterized by comprising the following steps:
s1, blast furnace molten iron: the molten iron is used as a main raw material for converter steelmaking, physical heat and chemical heat are provided for converter smelting, the tapping temperature is more than or equal to 1500 ℃, and the molten iron comprises the following components: c: 4.0% or more, Si: 0.40-0.60%, Mn: 0.30-0.60%, P: 0.130% or less, S: less than or equal to 0.035%;
s2, adding a steel bar pressing block into the ladle: adding a steel bar pressing block into the ladle before adding molten iron; the size of the steel bar pressing block is required to be less than or equal to 1800mm in length, less than or equal to 800mm in width and thickness, and the diameter of the steel bar is required to be 6-30 mm; controlling the adding amount of the steel bar pressing block to be 10-15 t, standing for 10-12 min after the steel bar pressing block is added, and then adding molten iron, wherein the adding amount of the molten iron is 80-85 t; after the molten iron is added into the ladle, the standing time is more than or equal to 10min, the added steel bar pressing block is ensured to be completely molten, and the temperature of the molten iron is ensured to be more than or equal to 1250 ℃;
s3, converter charging: keeping high-heat slag with the temperature of 1300 ℃ or higher after slag splashing from the previous furnace for 1.0-2.0 t, adding 22-30 t of scrap steel into the converter by using a scrap steel hopper, wherein the single piece of scrap steel is not more than 1t, the adding amount of slag steel in the scrap steel is not more than 5% of the amount of the scrap steel, adding 0-3 t of pig iron according to the conditions of molten iron and the scrap steel to improve the chemical heat of the molten steel, adding the molten iron into the converter, and blowing;
s4, converter blowing: controlling the oxygen pressure of an oxygen lance for converter blowing to be 0.78-0.86 MPa; activating a molten pool, ensuring that scrap steel is completely melted in the blowing process, adopting a low-position mode, a high-position mode and a low-position mode for a gun position, controlling the low position to be 1650-1900 mm by an oxygen gun position at the early stage, and quickly heating; the middle oxygen lance position control high position is 1900 mm-2200 mm, and the later oxygen lance position control low position is 1400 mm-1550 mm; adding stamping excess scrap steel with the diameter less than or equal to 60mm and the thickness of 4-10 mm through an overhead bunker in the blowing process, wherein the stamping excess scrap steel is required to have a smooth surface without hanging thorns; adding 0.8-2.4 t of stamping excess scrap steel, and strictly adding the scrap steel after oxygen supply and blowing for 600 s; the smelting end point target C is more than or equal to 0.06 percent, and the temperature is more than or equal to 1580 ℃;
s5, alloying in tapping: tapping time is controlled to be 150-350 s, and ladle off-line time is less than or equal to 60 min; adding the steel bar head and/or stamping residual scrap steel along with the alloy again in the tapping process, wherein the total adding amount is 0.3-1 t, and strictly forbidding slag discharging in the tapping process, wherein the thickness of a slag layer is required to be less than or equal to 30 mm; soft argon blowing is carried out after the furnace, the liquid level is required to slightly surge, the molten steel is not exposed, and the argon blowing time is more than or equal to 5 min;
s6, hoisting the steel ladle to an LF furnace for refining treatment or hoisting to a continuous casting machine for casting after argon blowing is finished;
the smelting method does not increase a scrap steel preheating facility, and does not add coke and silicon carbide into the converter.
2. The smelting method for increasing the scrap steel ratio according to claim 1, wherein the tapping temperature in the step S1 is 1550 ℃ or higher, and the steel bar head and/or the stamping excess scrap steel are/is added into the torpedo ladle for 4-7 t during the tapping process.
3. The smelting method for increasing the scrap ratio according to claim 1, wherein in the step S6, in the process of hoisting the ladle to an LF furnace for refining treatment, 0.5-2 t of stamping excess scrap steel is added into the ladle, and then the temperature of molten steel is increased by an electric heating mode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210441000.XA CN114540568B (en) | 2022-04-26 | 2022-04-26 | Smelting method for improving scrap steel ratio |
Applications Claiming Priority (1)
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