CN115305307B - Method for rapidly dissolving early-stage slag of converter by double-slag method and application - Google Patents

Method for rapidly dissolving early-stage slag of converter by double-slag method and application Download PDF

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CN115305307B
CN115305307B CN202210976606.3A CN202210976606A CN115305307B CN 115305307 B CN115305307 B CN 115305307B CN 202210976606 A CN202210976606 A CN 202210976606A CN 115305307 B CN115305307 B CN 115305307B
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slag
converter
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equal
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CN115305307A (en
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孙彪
沈昶
王勇
牛金印
解文中
张晓峰
王猛
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Maanshan Iron and Steel Co Ltd
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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
    • C21C5/36—Processes yielding slags of special composition
    • 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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  • Metallurgy (AREA)
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Abstract

The invention provides a method for rapidly dissolving early-stage slag in a converter double-slag method and application thereof, which can greatly improve the melting speed of block-shaped slag making materials, can stably control the alkalinity of the early-stage slag to be 2.5-3.0, and can greatly improve the dephosphorization rate of the early-stage slag from 20-40% to 60-70%; the invention can greatly improve the stability of the end point phosphorus content of the converter and can be stably controlled below 0.005%; meanwhile, the method can reduce the consumption of slag making materials in the decarburization period, reduce the labor intensity and is convenient and simple to operate.

Description

Method for rapidly dissolving early-stage slag of converter by double-slag method and application
Technical Field
The invention belongs to the technical field of converter processes, and particularly relates to a method for rapidly dissolving early-stage slag of a converter by a double-slag method and application of the method.
Background
With the progress of technology, high-quality steel such as automobile steel, low-temperature oil gas pipeline steel, steel for alpine regions, industrial pure iron and other products are increasingly widely applied, and as phosphorus can cause the rise of ductile-brittle transition temperature of the steel, the impact toughness of the steel is reduced to cause cold brittleness, and the welding performance of the steel is deteriorated. Therefore, phosphorus is a harmful element for most steel grades, and strict requirements are imposed on the phosphorus content. Phosphorus in molten iron is derived from iron ore used as an iron-making raw material, and thus one of the main tasks of converter steelmaking is dephosphorization.
The iron and steel enterprises are continuously reinforced in the aspect of cost control, and the use of low-cost high-phosphorus ores causes the too high phosphorus content of molten iron, thereby providing new challenges for steelmaking process control. The converter double slag method is widely used by various large steel plants as an economical and efficient smelting method, but in order to improve the level of stable control of the end point phosphorus content when smelting ultra-low phosphorus steel by using the double slag method, slag forming materials such as massive lime, dolomite and the like are required to be added from the top, and the massive slag forming materials cannot be completely melted in a short time due to shorter earlier blowing time, so that the earlier alkalinity is too low, the dephosphorization rate is not high, and the temperature measurement and sampling are difficult.
The method realizes the rapid deslagging of the slag in the early stage of the double slag method by greatly changing the gun position and the method of bottom blowing lime powder, but can lead to stable operation without using a converter by greatly changing the gun position in the Chinese patent 'a double slag method smelting process' (publication number is CN 109097523A) published in 12 and 28 of 2018; in addition, the process for bottom blowing lime powder needs to reform the existing bottom blowing system, and has high investment cost.
Chinese patent publication No. CN 105624358A (published in 6 months and 1 month) discloses a method for producing low-phosphorus steel by using a single converter and double oxygen guns, wherein the method realizes early stage rapid slag melting by adding a special dephosphorization gun with a powder spraying function, but the technology needs to add a special oxygen gun and increases investment cost; the technology realizes rapid slag melting by a method of spraying powder from a top lance, and increases smelting cost; in addition, the technology cannot realize the function for a part of steel plants with limited plants.
The method for smelting by adopting corundum slag through a double slag method in a converter disclosed in the Chinese patent No. 5 and 31 of 2017 ((publication No. CN 106755714A) mainly adopts bauxite to be added into the converter before dephosphorization slag is poured out to adjust the fluidity of slag, so that the quantity of the dephosphorization slag is ensured to be more than 70%, however, the addition of bauxite inevitably reduces the phosphorus content of the slag, thereby reducing the dephosphorization capability of the slag.
Disclosure of Invention
The invention aims to provide a method for quickly dissolving early-stage slag in a converter by a double-slag method, which solves the problems of slow slag dissolving, low slag alkalinity and low early-stage dephosphorization rate of the existing block slag making materials after adding by redesigning the adding mode of the block slag making materials.
The invention also aims to provide an application of the converter double slag method early slag rapid slagging method for producing ultra-low phosphorus steel.
The specific technical scheme of the invention is as follows:
a method for quickly melting early-stage slag of a converter by a double-slag method comprises the following steps:
1) The slag remaining amount of the previous converter is controlled to be 50-65% of the total slag mass;
2) Setting the flow rate of slag splashing gas to be 3.6-4.0 Nm 3 When the gun is positioned at the oxygen opening point, the material is openedAdding 65% -75% of the required total amount of block-shaped slag materials into the bin, and continuing to spray slag after the slag materials are added;
3) After slag splashing is finished, after the condition of slag in the furnace is confirmed by the shaking furnace, continuing to mix molten iron and scrap steel, wherein the ratio of the molten iron is controlled between 0.78 and 0.85;
4) After the oxygen lance is put down for converting for 30-45 s, adding the rest 25-35% of block slag making materials, and reducing the lance position to 1.1-1.3 m for converting; the gun position is reduced to 1.0-1.1 m 30-45 s before deslagging; the furnace pouring time is controlled between 5min and 30 s-6 min.
In the step 1), the slag remaining amount is controlled to be 50-65%, and the purpose is to utilize the high-alkalinity slag at the end point of the previous furnace so as to achieve the purposes of rapid slag formation and lime consumption reduction;
in the step 2), adding block-shaped slag making materials to ensure that the slag making materials are uniformly spread on the slag;
in the step 2), the gun position is positioned at an oxygen opening point, and at the moment, 65-75% of the total amount of block-shaped slag making materials are added by opening the feed bin, so that the added slag materials are uniformly dispersed in slag by using high-speed gas jet flow at the oxygen opening point, and the slag can be conveniently and quickly splashed and dried; meanwhile, because the high-alkalinity slag is more beneficial to dephosphorization, if the slag-making material is added during open blowing, the slag-making material is not easy to melt due to short time, and the dephosphorization purpose cannot be achieved; in addition, the final slag contains more (FeO) and (Fe) 2 O 3 ) And (SiO) 2 ) Iso-oxides, where (FeO), (Fe 2 O 3 ) Fe of oxide 2+ 、Fe 3+ The ionic radius is small, the ionic radius is easy to permeate and diffuse into the lime block, and the ionic radius and CaO in the slag material are subjected to chemical reaction to form low-melting-point compound melts such as (CaO. FeO) and (CaO. Fe) 2 O 3 )、(2CaO·Fe 2 O 3 ) Etc., when the slag is splashed, the slag making material is added, so that the CaO in the slag making material has enough time to be mixed with (FeO) and (Fe) in the slag material 2 O 3 ) The reaction ensures that the slagging material is fully melted, and is convenient for rapid slagging in the initial stage of blowing.
In the step 2), the total amount of the block slag-making materials which are needed to be added in the next furnace front-stage slag-making is calculated according to the final slag alkalinity of the front furnace, the slag-remaining amount, the silicon content of the molten iron of the next furnace, the target alkalinity of the front-stage slag and the like, and is generally between 3.5 and 25kg/t iron;
in the step 2), the blocky slag-forming material comprises 80-90% of metallurgical lime and 10-20% of light burned dolomite by mass percent;
the technical requirements of the metallurgical lime in the step 2) are as follows: caO is more than or equal to 90.0wt percent and SiO 2 Less than or equal to 3 weight percent, the activity degree is more than or equal to 230ml, the caustic soda is less than or equal to 10.0 weight percent, and the content of granularity of 5-50 mm is more than or equal to 90.0 weight percent;
the technical requirements of the light burned dolomite in the step 2) are as follows: caO is more than or equal to 45.0wt%, mgO is more than or equal to 30.0wt%, P is less than or equal to 0.030wt%, caustic soda is less than or equal to 13.0wt%, and the content of granularity of 5-60 mm is more than or equal to 80.0wt%;
step 3) the furnace shaking confirms the condition of the slag in the furnace, wherein the step is to confirm whether the slag splashes dry or not, and the slag splashes dry must be ensured to continue the later operation, such as: adding molten iron, otherwise, safety accidents are easy to occur;
in the step 3), the ratio of molten iron is controlled between 0.78 and 0.85, so that proper temperature is ensured, and the blowing operation is facilitated;
in the step 3), the bottom blowing strength is 0.05-0.10 Nm 3 /(t·min)；
In the step 4), after the oxygen lance is blown for 30-45 seconds, adding the rest 25-35% of slag making materials, ensuring that the slag making materials are added after ignition, and lowering the lance position to 1.1-1.3 m for blowing so as to ensure sufficient stirring and rapid slag melting; when the gun position is reduced to 1.0-1.1 m before pouring for 30-45 s, the gun position is reduced to press slag before pouring in order to prevent serious foaming of the slag after pouring; the furnace pouring time is controlled to be between 5min and 30s and 6min, so that the furnace pouring time is controlled to ensure good slag permeabilization and dephosphorization effect.
In the step 4), the temperature measurement and sampling are carried out by reversing the furnace, and the temperature of the reversing furnace is controlled between 1380 and 1450 ℃; the alkalinity of the slag is controlled between 2.5 and 3.0, and the content of ferric oxide in the slag can be controlled between 16 and 25 percent;
after the step 4) treatment, the total melting of the added slag can be ensured, the dephosphorization rate is more than 60%, and the P content in the molten steel can be controlled between 0.030 and 0.050%;
in the step 4), the deslagging amount is controlled between 50 and 65 percent;
further, after the furnace is reversed, 10-20 kg/t of iron slag former is added, and secondary slag formation and decarburization are carried out subsequently;
further, the final temperature is controlled to be 1590-1610 ℃, the final slag alkalinity is controlled to be 3.5-4.0, and the final P content can be controlled to be below 0.005%.
The invention provides an application of a converter double slag method early stage slag rapid slagging method, which is used for producing ultra-low phosphorus steel, in particular to steel with P content below 0.005%.
The invention provides a method capable of rapidly melting block-shaped slag, which can greatly improve the melting speed of the block-shaped slag, stably control the alkalinity of the earlier-stage slag between 2.5 and 3.0, and greatly improve the dephosphorization rate of the earlier-stage slag from 20 to 40 percent to 60 to 70 percent; the invention can greatly improve the stability of the end point phosphorus content of the converter and can be stably controlled below 0.005%; meanwhile, the method can reduce the consumption of slag making materials in the decarburization period, reduce the labor intensity and is convenient and simple to operate.
Detailed Description
The invention provides a method for quickly dissolving early-stage slag of a converter by a double-slag method, which comprises the following steps:
1) The slag remaining amount of the previous converter is controlled to be 50-65% of the total slag mass;
2) Calculating the total addition amount of the block slag making materials required to be added in the next stokehold slag making according to the final slag alkalinity of the stokehold, the slag remaining amount, the silicon content of the molten iron of the next stokehold, the target alkalinity of the stokehold slag and the like, wherein the total addition amount is generally between 3.5 and 25kg/t iron; the block slag-forming material comprises 80-90% of metallurgical lime and 10-20% of light burned dolomite; preparing 65-75% of the addition amount of the required blocky slag-making materials according to the calculation result; setting the flow rate of slag splashing gas to be 3.6-4.0 Nm 3 When the gun is used for slag splashing, stopping when the gun position is positioned at the position where gas is just opened, opening a feed bin to add blocky slag making materials at the moment, ensuring that the slag making materials are evenly spread on slag, and continuing to perform slag splashing operation according to a normal flow after the slag making materials are added;
3) After slag splashing is completed, the furnace is rocked according to the normal flow to confirm the condition of slag in the furnace, and then molten iron is continuously addedThe scrap steel operation is carried out, and the molten iron ratio is controlled to be between 0.78 and 0.85; bottom blowing strength of 0.05-0.010 Nm 3 /(t·min)；
4) When the oxygen lance is used for converting for 30-45 s, adding the rest 25-35% of block slag-making materials, and reducing the lance position to 1.1-1.3 m for converting; when the gun position is reduced to 1.0-1.1 m until 30-45 s before deslagging, the time for deslagging is controlled between 55min and 30 s-6 min; at the moment, the temperature of the furnace is measured and sampled, and the temperature of the furnace is controlled to be 1380-1450 ℃; the alkalinity of the slag is controlled between 2.5 and 3.0, and the content of ferric oxide in the slag can be controlled between 16 and 25 percent; at the moment, the slag charge can be completely melted, the dephosphorization rate is more than 60%, and the P content in the molten steel can be controlled between 0.030 and 0.050 percent; the slag pouring amount is controlled between 50 and 60 percent;
5) Pouring the iron slag former into the furnace, adding 10-20 kg/t of the iron slag former, and performing secondary slag formation and decarburization subsequently;
the final temperature is controlled between 1590 and 1610 ℃, the final slag alkalinity is controlled between 3.5 and 4.0, and the final P content can be controlled below 0.005%.
Several preferred embodiments of the invention are as follows: the technical requirements of the metallurgical lime used in the invention are as follows: caO is more than or equal to 90.0wt percent and SiO 2 Less than or equal to 3 weight percent, the activity degree is more than or equal to 230ml, the caustic soda is less than or equal to 10.0 weight percent, and the content of granularity of 5-50 mm is more than or equal to 90.0 weight percent; the technical requirements of the light burned dolomite are as follows: caO is more than or equal to 45.0wt%, mgO is more than or equal to 30.0wt%, P is less than or equal to 0.030wt%, caustic soda is less than or equal to 13.0wt%, and the content of granularity of 5-60 mm is more than or equal to 80.0wt%.
Example 1
A method for quickly melting early-stage slag of a converter by a double-slag method comprises the following steps:
the method is implemented on a 120-ton top-bottom combined blown converter: the composition of the smelted steel grade is shown in the following table 1, and the balance of Fe and unavoidable impurities which are not shown in the table 1;
table 1 example 1 smelting steel grade composition
The slag remaining amount of the previous converter is 6t (the slag remaining amount controls 50% of the total slag amount)) Target alkalinity is 2.5, the ratio of molten iron is 0.78, the silicon content of molten iron is 0.25%, and the phosphorus content in molten iron is 0.120%. Adding 850kg of lime and 150kg of light burned dolomite according to the calculation requirement; preparing 560kg lime, 140kg light burned dolomite, and setting splash slag N 2 Flow rate 3.85Nm 3 After the slag is splashed, the gun is stopped when the gun position reaches 4.26m (the distance from the steel liquid level, namely the oxygen starting point), a storage bin is opened at the moment, the prepared block slag is added, and after the slag is added, the gun is continuously started to splash slag according to the normal flow.
After slag splashing is completed, the furnace is rocked according to the normal flow to confirm the condition of slag in the furnace, and then the operation of adding molten iron and scrap steel is continued, and the bottom blowing strength is 0.05Nm 3 /(t.min); when the oxygen lance is used for converting for 30s, the rest 300kg of block slag materials are added, the lance position is reduced to 1.1m for converting, when the oxygen lance is used for converting for 5min, the lance position is reduced to 1.05m, and when the oxygen lance is used for converting for 5min for 40s, the oxygen lance is lifted and the oxygen lance is poured into the furnace. The pouring temperature is 1390 ℃, the added slag is observed to be totally melted, the alkalinity of the slag is 2.52, the iron oxide content in the slag is 18.2%, the phosphorus content in the steel is 0.036%, the dephosphorization rate is 70%, and the pouring amount is 55%.
And after the furnace is reversed, secondary slagging and decarburization are completed, the adding amount of slag making materials is 1500kg, the final temperature is 1595 ℃, the final slag alkalinity is 3.6, and the final phosphorus content is 0.005%.
Example 2
A method for quickly melting early-stage slag of a converter by a double-slag method comprises the following steps:
the method is implemented on a 120-ton top-bottom combined blown converter: the balance of Fe and unavoidable impurities, which are not shown in the following tables 2 and 2, are the smelting steel ingredients;
table 2 example 2 smelting steel grade composition
The slag remaining amount of the previous converter is 6.5t (the slag remaining amount controls 54 percent of the total slag amount), the target alkalinity is 2.8, the molten iron ratio is 0.81, the silicon content of molten iron is 0.45 percent, and the phosphorus content in the molten iron is 0.115 percent. Adding 2000kg of lime and 400kg of light burned dolomite according to the calculation requirement; 1400kg lime, 280kg light burned dolomite and splash slag N are prepared 2 Flow rate 3.85Nm 3 After the slag is splashed, the gun is stopped when the gun position reaches 4.26m (the distance from the steel liquid level, namely the oxygen starting point), a storage bin is opened at the moment, the prepared block slag is added, and after the slag is added, the gun is continuously started to splash slag according to the normal flow.
After slag splashing is completed, the furnace is rocked according to the normal flow to confirm the condition of slag in the furnace, and then the operation of adding molten iron and scrap steel is continued, and the bottom blowing strength is 0.08Nm 3 /(t.min); when the oxygen lance is used for converting for 35s, the rest 720kg of slag-making materials are added, the lance position is reduced to 1.3m for converting, when the oxygen lance is used for converting for 5min20s, the lance position is reduced to 1.10m, and when the oxygen lance is used for converting for 5min55s, the oxygen lance is lifted and the oxygen lance is poured into the furnace. The temperature of the furnace is 1410 ℃ and the slag is totally melted, the alkalinity of the slag is controlled at 2.79, the iron oxide content in the slag is 20%, the phosphorus content in the steel is 0.040%, and the dephosphorization rate is 65.2%. The slag pouring amount is 56%.
And after the furnace is reversed, secondary slagging and decarburization are completed, the addition amount of the slagging agent is 1800kg, the final temperature is 1605 ℃, the final slag alkalinity is 3.9, and the final phosphorus content is 0.004%.
Example 3
A method for quickly melting early-stage slag of a converter by a double-slag method comprises the following steps:
the method is implemented on a 120-ton top-bottom combined blown converter: the composition of the smelted steel grade is shown in the following table 3, and the balance which is not shown in the table 3 is Fe and unavoidable impurities;
table 3 example 3 smelting steel grade composition
The slag remaining amount of the previous converter is 6.8t (the slag remaining amount controls 57 percent of the total slag amount), the target alkalinity is 3.0, the molten iron is 0.82 ratio, the silicon content of the molten iron is 0.55 percent, and the phosphorus content of the molten iron is 0.135 percent. Adding lime 2600kg and light burned dolomite 550kg according to the calculation requirement; 1820kg lime and 385kg light burned dolomite are prepared, and splash slag N is set 2 Flow rate 3.85Nm 3 After the slag splashing is carried out, the gun is started to splash slag, the gun position is stopped when reaching 4.26m (the distance from the steel liquid level, namely the oxygen starting point), at the moment, a storage bin is opened to add prepared block slag materials, and after the slag materials are added, the gun is continuously started according to the positive directionAnd performing slag splashing operation in a normal flow.
After slag splashing is completed, the furnace is rocked according to the normal flow to confirm the condition of slag in the furnace, and then the operation of adding molten iron and scrap steel is continued, and the bottom blowing strength is 0.06Nm 3 /(t.min); adding 945kg of slag charge when the oxygen lance is put down for converting for 38s, reducing the lance position to 1.25m for converting, reducing the lance position to 1.10m when the oxygen lance is put down for 18s, and lifting the lance and pouring the slag charge when the oxygen lance is put down for 56 s. The temperature of the furnace is 1400 ℃, the slag charge is completely melted, the alkalinity of the slag is controlled at 2.95, the iron oxide content in the slag is 21%, the phosphorus content in the steel is 0.045%, and the dephosphorization rate is 66.7%. The slag pouring amount is 59%.
And after the furnace is reversed, the secondary slagging and decarburization are completed, the addition amount of the slagging agent is 1900kg, the final temperature is 1610 ℃, the final slag alkalinity is 3.95, and the final phosphorus content is 0.005%.
Example 4
A method for quickly melting early-stage slag of a converter by a double-slag method comprises the following steps:
the method is implemented on a 70-ton top-bottom combined blown converter: the composition of the steel grade is shown in the following table 4, and the balance of Fe and unavoidable impurities which are not shown in the table 4;
table 4 example 4 smelting steel grade composition
The slag remaining amount of the previous converter is 4.2t (the slag remaining amount controls 60 percent of the total slag amount), the target alkalinity is 2.8, the molten iron is 0.82 ratio, the silicon content of the molten iron is 0.45 percent, and the phosphorus content of the molten iron is 0.130 percent. Adding 200kg of lime 1300kg of light burned dolomite according to the calculation requirement; preparing 910kg lime, 140kg light burned dolomite, and setting splash slag N 2 Flow rate 3.73Nm 3 After the slag is splashed, the gun is stopped when the gun position reaches 3.5m (the distance from the steel liquid level, namely the oxygen starting point), a storage bin is opened at the moment, the prepared block slag is added, and after the slag is added, the gun is continuously started to splash slag according to the normal flow.
After slag splashing is completed, the furnace is rocked according to the normal flow to confirm the condition of slag in the furnace, and then the operation of adding molten iron and scrap steel is continued, and the bottom blowing strength is 0.05Nm 3 /(t.min); oxygen gasWhen the gun is used for converting for 32s, the rest 450kg of slag-making materials are added, the gun position is reduced to 1.20m for converting, when the gun position is reduced to 1.10m for converting for 5min10s, and when the gun position is converted for 5min50s, the gun is lifted and the furnace is reversed. The temperature of the furnace is 1405 ℃, the added slag is observed to be totally melted, the alkalinity of the slag is controlled at 2.75, the iron oxide content in the slag is 20%, the phosphorus content in the steel is 0.049%, and the dephosphorization rate is 62.3%. The slag pouring amount is 56%.
And after the furnace is reversed, secondary slagging and decarburization are completed, the adding amount of the slagging agent is 1300kg, the final temperature is 1603 ℃, the final slag alkalinity is 3.90, and the final phosphorus content is 0.005%.
Example 5
A method for quickly melting early-stage slag of a converter by a double-slag method comprises the following steps:
the method is implemented on a 300-ton top-bottom combined blown converter: the composition of the steel grade is shown in the following table 5, and the balance of Fe and unavoidable impurities, which are not shown in the table 5;
table 5 example 5 smelting steel grade composition
The slag remaining amount of the previous converter is 19t (the slag remaining amount controls 63% of the total slag amount), the target alkalinity is 2.5, the molten iron is 0.82 ratio, the silicon content of molten iron is 0.45%, and the phosphorus content of molten iron is 0.120%. Adding 8000kg of lime and 1000kg of light burned dolomite according to the calculation requirement; preparing 5600kg lime, 700kg light burned dolomite, setting splash slag N 2 Flow rate 3.78Nm 3 After the slag is splashed, the gun is stopped when the gun position reaches 4.6m (the distance from the steel liquid level, namely the oxygen starting point), a storage bin is opened at the moment, the prepared block slag is added, and after the slag is added, the gun is continuously started to splash slag according to the normal flow.
After slag splashing is completed, the furnace is rocked according to the normal flow to confirm the condition of slag in the furnace, and then the operation of adding molten iron and scrap steel is continued, and the bottom blowing strength is 0.09Nm 3 /(t.min); when the oxygen lance is used for converting for 35s, the rest 2700kg of slag making material is added, the lance position is reduced to 1.30m for converting, when the oxygen lance is used for converting for 5min20s, the lance position is reduced to 1.10m for converting for 5min55s, and when the oxygen lance is used for converting, the oxygen lance is lifted and the oxygen lance is poured into the furnace. The temperature of the furnace is 1415 ℃ and the slag charge is observed to be totally melted,the basicity of the slag is controlled to be 2.80, the iron oxide content in the slag is 19%, the phosphorus content in the steel is 0.047%, and the dephosphorization rate is 60.8%. The slag pouring amount is 58%.
And after the furnace is reversed, secondary slagging and decarburization are completed, the adding amount of the slagging agent is 3500kg, the final slag alkalinity is 3.85, and the final phosphorus content is 0.0045%.
Comparative example 1
A method for quickly melting early-stage slag of a converter by a double-slag method comprises the following steps:
the method is implemented on a 70-ton top-bottom combined blown converter: the composition of the steel grade is shown in the following table 6, and the balance of Fe and unavoidable impurities which are not shown in the table 6;
table 6 comparative example 1 smelting steel grade composition
The slag remaining amount of the previous converter is 4.0t, the target alkalinity is 2.6, the molten iron is 0.81 ratio, the silicon content of the molten iron is 0.48%, and the phosphorus content in the molten iron is 0.120%. Adding 1350kg of lime and 200kg of light burned dolomite according to the calculation requirement; 945kg lime is prepared, 140kg light burned dolomite is prepared, and splash slag N is set 2 Flow rate 3.73Nm 3 After the slag is splashed, the gun is stopped when the gun position reaches 3.5m (the distance from the steel liquid level, namely the oxygen starting point), a storage bin is opened at the moment, the prepared block slag is added, and after the slag is added, the gun is continuously started to splash slag according to the normal flow.
After slag splashing is completed, the furnace is rocked according to the normal flow to confirm the condition of slag in the furnace, and then the operation of adding molten iron and scrap steel is continued, and the bottom blowing strength is 0.02Nm 3 /(t.min); when the oxygen lance is used for converting for 35s, the rest 465kg of slag-making material is added, the lance position is reduced to 1.20m for converting, when the lance position is reduced to 1.10m for converting for 5min20s, and when the lance position is reduced to 5min55s for converting, the lance is lifted and the furnace is reversed. The temperature of the furnace is 1398 ℃, the added slag is observed to be totally melted, the alkalinity of the slag is controlled to be 2.55, the iron oxide content in the slag is 22%, the phosphorus content in the steel is 0.075%, and the dephosphorization rate is 37.5%. The slag pouring amount is 55%.
And after the furnace is reversed, secondary slagging and decarburization are completed, the adding amount of the slagging agent is 2500kg, the final temperature is 1590 ℃, the final slag alkalinity is 4.2, and the final phosphorus content is 0.008%.
The dephosphorization rate at the earlier stage is only 37.5 percent, because the converter age exceeds 10000 furnaces, the bottom blowing ventilation holes are blocked, the bottom blowing strength is very low, and the dephosphorization rate is only 0.02Nm 3 It is impossible to satisfy the plantar blowing strength of 0.05 to 0.10Nm 3 Within the range of/(t.min). In order to ensure that the end point P content can meet the requirement, forced reblowing is to increase the lime consumption by 1200kg.

Claims (9)

1. The method for quickly dissolving the early-stage slag of the double-slag method of the converter is characterized by comprising the following steps of:
1) The slag remaining amount of the previous converter is controlled to be 50-65% of the total slag mass;
2) Setting the flow rate of the slag splashing gas to be 3.6-4.0 Nm 3 When the gun is positioned at an oxygen opening point, a feed bin is opened to add 65% -75% of the total amount of the block-shaped slag materials, and after the slag materials are added, the gun is continuously started to perform slag splashing operation;
3) After slag splashing is completed, after the condition of slag in the furnace is confirmed by the shaking furnace, continuing to mix molten iron and scrap steel, wherein the ratio of the molten iron is controlled to be 0.78-0.85;
4) After the oxygen lance is put down for converting for 30-45 s, adding the rest 25-35% of blocky slag making materials, and reducing the lance position to 1.1-1.3 m for converting; the gun position is reduced to 1.0-1.1 m until 30-45 s before deslagging; the furnace pouring time is controlled to be 5min30 s-6 min.
2. The method for rapidly dissolving the primary slag in the double slag process of the converter of claim 1, wherein in the step 2), the block-shaped slag forming material comprises 80-90% of metallurgical lime and 10-20% of light burned dolomite.
3. The method for rapid deslagging of the converter double slag process pre-slag according to claim 2, wherein the metallurgical lime technical requirements in step 2) are as follows: caO is more than or equal to 90.0wt percent and SiO 2 Less than or equal to 3wt%, the activity degree is more than or equal to 230ml, the caustic soda is less than or equal to 10.0wt%, and the content of granularity of 5-50 mm is more than or equal to 90.0wt%; the light burned dolomite technologyThe operation requirements are as follows: caO is more than or equal to 45.0wt%, mgO is more than or equal to 30.0wt%, P is less than or equal to 0.030wt%, caustic soda is less than or equal to 13.0wt%, and the content of granularity of 5-60 mm is more than or equal to 80.0wt%.
4. The method for rapid deslagging of the converter double slag method early slag, as set forth in claim 1, characterized in that in the step 3), the bottom blowing strength is 0.05-0.010Nm 3 /（t·min）。
5. The method for rapidly melting the early-stage slag of the double slag method of the converter according to claim 1, wherein in the step 4), the temperature of the converter is controlled to be 1380-1450 ℃ by temperature measurement and sampling; the alkalinity of the slag is controlled to be 2.5-3.0, and the content of ferric oxide in the slag can be controlled to be 16-25%.
6. The method for rapidly dissolving the primary slag in the double slag method of the converter of claim 1, wherein the dephosphorization rate is more than 60% after the treatment in the step 4), and the P content in the molten steel can be controlled to be 0.030-0.050%.
7. The method for rapidly dissolving the primary slag in the double slag method of the converter of claim 1, wherein in the step 4), the deslagging amount is controlled to be 50-65%.
8. The method for rapidly dissolving the primary slag in the double slag process of the converter of claim 1, wherein the final temperature is controlled to be 1590-1610 ℃, the final slag alkalinity is controlled to be 3.5-4.0, and the final P content is controlled to be below 0.005%.
9. Use of the converter double slag method of the fast slag melting method of the earlier slag according to any one of claims 1-8, characterized in that it is used for the production of ultra-low phosphorus steel.
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JP2005206924A (en) * 2004-01-26 2005-08-04 Kobe Steel Ltd Molten iron refining method
CN109097523A (en) * 2018-08-31 2018-12-28 钢铁研究总院 A kind of double slag process smelting process
CN110117689A (en) * 2019-06-11 2019-08-13 北京科技大学 A method of based on high-silicon molten iron converter double slag process low phosphorus steel by smelting
CN111719032A (en) * 2019-03-21 2020-09-29 本钢板材股份有限公司 Converter less-slag smelting method

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Publication number Priority date Publication date Assignee Title
US6503442B1 (en) * 2001-03-19 2003-01-07 Praxair S.T. Technology, Inc. Metal-zirconia composite coating with resistance to molten metals and high temperature corrosive gases

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Publication number Priority date Publication date Assignee Title
JP2005206924A (en) * 2004-01-26 2005-08-04 Kobe Steel Ltd Molten iron refining method
CN109097523A (en) * 2018-08-31 2018-12-28 钢铁研究总院 A kind of double slag process smelting process
CN111719032A (en) * 2019-03-21 2020-09-29 本钢板材股份有限公司 Converter less-slag smelting method
CN110117689A (en) * 2019-06-11 2019-08-13 北京科技大学 A method of based on high-silicon molten iron converter double slag process low phosphorus steel by smelting

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