CN113106190B - Steelmaking method for obtaining high-manganese low-phosphorus molten steel through converter smelting - Google Patents
Steelmaking method for obtaining high-manganese low-phosphorus molten steel through converter smelting Download PDFInfo
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- C21—METALLURGY OF IRON
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Abstract
The invention provides a steelmaking method for obtaining high-manganese low-phosphorus molten steel by converter smelting, which comprises the following steps: after the converter is added with molten iron/semisteel, slagging is carried out, then oxygen blowing by a top-blowing oxygen lance and air supply by bottom blowing are carried out until the carbon content of molten steel and the temperature of the molten steel reach certain valuesStopping oxygen blowing at the target; then, blowing inert gas by using a top-blowing oxygen lance, simultaneously adding a carbonaceous reducing agent, and increasing the gas supply intensity of bottom blowing to 0.08-0.15 m3V (min ton steel); wherein the conditions for blowing the inert gas by the top-blowing oxygen lance are as follows: the gas supply intensity is 2.5-3.5 m3V (min. ton steel), the position of the oxygen lance is 1.5-2 m; the gas for bottom blowing is inert gas; and tapping until the end point molten steel temperature and the end point molten steel carbon content reach certain targets to obtain the high-manganese low-phosphorus molten steel. The steelmaking method can improve the content of residual manganese at the end point of the converter, ensure the dephosphorization effect and reduce the content of total iron in the final slag.
Description
Technical Field
The invention relates to the technical field of metallurgy, in particular to a steelmaking method for obtaining high-manganese low-phosphorus molten steel through converter smelting.
Background
In the steel-making production, manganese is an essential alloying element, and has important effects on improving the quality of steel and the performance of the steel. In fact, the molten iron smelted by the converter contains 0.15-0.40% of manganese, but the manganese in the molten iron enters slag due to oxygen blowing oxidation in the converter smelting process, so that the manganese content of the molten steel at the end point after the converter blowing is finished is very low, and is only 0.04-0.08% on average. For semi-steel smelting, because the manganese is basically oxidized and enters vanadium slag after vanadium extraction, the average manganese content in the obtained semi-steel is only 0.02-0.04%, and therefore, the manganese content in the molten steel at the end point of a semi-steel smelting converter is lower and is only 0.01-0.03% on average.
Aiming at the problems, the manganese content of the end-point molten steel can be improved by a certain technical means. At present, most iron and steel enterprises perform manganese alloying operation on molten steel by adding ferromanganese alloy in the tapping process or refining process. Such as: adding manganese ore to improve the manganese content of end-point molten steel, wherein the patent application with the application number of 201610305864.3 discloses a technology for applying manganese ore direct alloying to converter steelmaking, the converter steelmaking technology adopts a one-time carbon drawing method, the FeO content of final slag is 13-15%, the average smelting period is 12.3min, manganese alloy ore is added into a converter in batches within 4-10 min after the converter steelmaking is started, and the adding amount of the manganese alloy ore in each converter is as follows: 10-14 kg/ton steel, end point carbon content: c is more than or equal to 0.08 percent; the end point temperature is 1650-1680 ℃, and the residual manganese content at the end point is increased by 0.16-0.20%. However, the above process has high requirements for TMn in manganese ore, high carbon content in molten steel at the end point, low temperature, low manganese yield in manganese ore, and poor comprehensive effect of the process.
Practice shows that the necessary thermodynamic conditions of the manganese in the end-point molten steel are improved during high-carbon, high-temperature and low-oxidability tapping.
However, dephosphorization is also one of the main tasks of converter smelting. Low temperature, high oxidizability (low carbon) and large slag amount (high alkalinity) are favorable conditions for dephosphorization. In order to improve the manganese content of the end-point molten steel and reduce the phosphorus content of the molten steel, the thermodynamic conditions are mutually contradictory, and the high-manganese and low-phosphorus steel tapping is difficult to realize simultaneously.
For example, patent application CN104060020 discloses a dephosphorization steelmaking method for increasing the end point manganese content of molten steel in a converter, which achieves the purposes of increasing the end point manganese content of the converter and dephosphorization steelmaking by rapidly tapping at the early stage of smelting (namely adding a proper amount of silicon increasing agent and then adding a proper amount of scrap steel after adding semisteel into a steelmaking converter), keeping slag active at the middle stage of smelting (namely adding a proper amount of manganese ore into the converter when the oxygen blowing progress is 30% -70%), and stirring reduced slag at the later stage of smelting by adopting large amount of argon (namely adding bottom blowing operation before tapping molten steel after oxygen blowing, increasing the bottom blowing argon strength compared with the oxygen blowing process and stirring under the improved bottom blowing argon strength). However, the above process requires the addition of a silicon-adding agent, scrap steel and manganese ore, and requires the addition in a certain order at a specific stage, the operation is complicated, and the raw material cost and the operation cost are high; meanwhile, the manganese content of the obtained molten steel is below 0.10%, the manganese yield of the molten steel is low, the total iron content of the final slag is above 17%, and the manganese extraction and iron extraction effects are poor; in addition, the slag has high oxidizability and seriously erodes the furnace lining. The main reason for the low manganese yield is to ensure the high oxidizability of the slag so as to achieve good dephosphorization effect, so that the low manganese and low phosphorus smelting can be realized only.
Disclosure of Invention
In view of the above, the invention aims to provide a steel-making method for obtaining high-manganese low-phosphorus molten steel by converter smelting. The steelmaking method provided by the invention can improve the content of residual manganese at the end point of the converter, ensure the dephosphorization effect and reduce the content of total iron in the final slag, and is simple to operate and capable of reducing the cost.
The invention provides a steelmaking method for obtaining high-manganese low-phosphorus molten steel by converter smelting, which comprises the following steps:
s1, after molten iron/semisteel is added into the converter, slagging is carried out, then oxygen blowing by a top-blowing oxygen lance and air supply by bottom blowing are carried out until the carbon content of the molten steel is 0.15-0.30% and the temperature of the molten steel reaches 1681-1700 ℃, and oxygen blowing is stopped;
the gas for bottom blowing gas supply is inert gas;
s2, blowing inert gas by using a top-blowing oxygen lance, adding a carbonaceous reducing agent, and increasing the gas supply intensity of bottom blowing to 0.08-0.15 m3V (min ton steel); wherein the conditions for blowing the inert gas by the top-blowing oxygen lance are as follows: the gas supply intensity is 2.5-3.5 m3(min. ton steel), the lance position of the oxygen lance is 1.5-2 m; the gas for bottom blowing is inert gas; and tapping until the temperature of the molten steel reaches 1660-1680 ℃ and the carbon content of the molten steel reaches 0.10% -0.15% at the end point to obtain the high-manganese low-phosphorus molten steel.
Preferably, in the step S1, the oxygen supply intensity of the top-blown oxygen lance is 2.5-3.5 m3/(min. ton steel).
Preferably, in the step S1, the air supply intensity of the bottom blowing air is 0.02-0.06 m3/(min. ton steel).
Preferably, in step S1, the inert gas is nitrogen or argon;
in the step S2, the inert gas is nitrogen or argon.
Preferably, in the step S1, the slagging material added in the slagging process is active lime and high-magnesium lime.
Preferably, the using amount of the active lime is 10-30 kg/t steel; the consumption of the high-magnesium lime is 5-20 kg/t steel.
Preferably, in step S2, the carbonaceous reducing agent is a reducing agent having a fixed carbon content of 90 wt% or more.
Preferably, in step S2, the carbonaceous reducing agent is one or more of anthracite, graphite-like coal and coke;
the particle size of the carbonaceous reducing agent is 5-15 mm;
the dosage of the carbonaceous reducing agent is 0.5-1.5 kg/t steel.
Preferably, in the step S2, the time for blowing the inert gas by the top-blown oxygen lance is 30 to 60 seconds;
in the steps S1 and S2, the carbon content and the temperature of molten steel are monitored by using a lance.
Preferably, in the step S1, after the converter is added with the semi-steel, the slag is formed and the manganese ore is added, and then the top-blown oxygen lance oxygen blowing and the bottom-blown gas supply are performed.
According to the steelmaking method provided by the invention, the step S1 and the step S2 are combined together and used in the same furnace for smelting, the carbon content of the molten steel in the first step is controlled to be 0.15% -0.30%, the temperature of the molten steel is controlled to be 1681-1700 ℃, and the carbon content and the temperature of the molten steel in the second step are controlled, so that the steel can be tapped at the end point of the converter through high manganese and low phosphorus in the molten steel, the problem that only low manganese steel can be tapped in the prior art for ensuring the dephosphorization effect is solved, and the method is simple to operate and high in economical efficiency.
Experimental results show that the smelting method can improve the manganese content of the end-point molten steel to be more than 0.19%, reduce the phosphorus content to be less than 0.007%, and reduce the total iron content of the slag to be less than 17%.
Detailed Description
The invention provides a steelmaking method for obtaining high-manganese low-phosphorus molten steel by converter smelting, which comprises the following steps:
s1, after molten iron/semisteel is added into the converter, slagging is carried out, then oxygen blowing by a top-blowing oxygen lance and air supply by bottom blowing are carried out until the carbon content of the molten steel is 0.15-0.30% and the temperature of the molten steel reaches 1681-1700 ℃, and oxygen blowing is stopped;
the gas for bottom blowing gas is inert gas;
s2, blowing inert gas by using a top-blowing oxygen lance, adding a carbonaceous reducing agent, and increasing the gas supply intensity of bottom blowing to 0.08-0.15 m3V (min ton steel); wherein the conditions for blowing the inert gas by the top-blowing oxygen lance are as follows: the gas supply intensity is 2.5-3.5 m3V (min. ton steel), the position of the oxygen lance is 1.5-2 m; the gas for bottom blowing is inert gas; and tapping until the temperature of the molten steel reaches 1660-1680 ℃ and the carbon content of the molten steel reaches 0.10% -0.15% at the end point to obtain the high-manganese low-phosphorus molten steel.
Regarding step S1:
in the invention, the molten iron is not particularly limited, and is conventional molten iron for steelmaking in the field. After the converter is added with molten iron, the charging and slagging are carried out. In the invention, the slagging materials added in the slagging process are preferably active lime and high-magnesium lime. The active lime is preferably used in an amount of 10-30 kg/t steel; in some embodiments of the invention, the amount is 10kg/t steel, 20kg/t steel, 30kg/t steel. The dosage of the high-magnesium lime is preferably 5-20 kg/t steel; in some embodiments of the invention, the amount is 15kg/t steel, 10kg/t steel, 15kg/t steel.
In the invention, if molten iron is added into the converter (namely the manganese content is more than or equal to 0.2%), only slagging is carried out (no manganese ore is needed to be added), and then the subsequent operations are carried out. If the converter is added with semisteel (namely the manganese content is less than 0.05%), manganese ore is added in the slagging process. In the invention, the addition amount of the manganese ore is preferably 8-20 kg/t steel. The method can realize the purpose of smelting high-manganese and low-phosphorus molten steel by a converter regardless of molten iron smelting or semisteel smelting, only needs to add certain manganese ore during slagging for semisteel smelting, and other steps are the same as those during molten iron smelting.
In the invention, after the steps, oxygen blowing by a top-blowing oxygen lance and air supply by bottom blowing are carried out.
The air supply intensity of oxygen blowing of the top-blown oxygen lance is preferably 2.5-3.5 m3V (min ton steel); in some embodiments of the invention, 2.5m3/(min. ton steel), 3.0m3/(min. ton steel), 3.5m3/(min. ton steel). The optimal lance position of the top-blown oxygen lance is 1.2-2.5 m. In some embodiments of the invention, the lance position is 1.2-1.9m, 1.4-2.2m, 1.6-2.5 m.
The gas for bottom blowing is inert gas. The inert gas is preferably nitrogen or argon, more preferably nitrogen. The air supply intensity of bottom blowing air supply is preferably 0.02-0.06 m3V (min ton steel); in some embodiments of the invention, 0.02m3/(min. ton steel), 0.05m3/(min. ton steel), 0.06m3/(min. ton steel).
In the invention, oxygen blowing and bottom blowing are carried out through the top-blowing oxygen lance, and oxygen blowing is stopped until the carbon content of the molten steel is 0.15-0.30% and the temperature of the molten steel reaches 1681-1700 ℃. In the invention, the carbon content of the molten steel and the temperature of the molten steel are monitored by the sublance, and once the target parameters are reached, oxygen blowing operation is executed. The action principle of the sublance is as follows: the thermocouple of the sublance can penetrate through a slag layer and is inserted into the molten steel to a depth of dozens of centimeters, the temperature, the carbon content and the like of the molten steel are detected, the temperature, the carbon content and the like of the molten steel are sent to the intermediate computer in the form of electric signals along the data transmission line, the intermediate computer converts the electric signals into digital signals of the temperature, the carbon content and the like of the molten steel and sends the digital signals to the secondary server, and finally, the molten steel information is presented to field operators. In some embodiments of the invention, the monitoring of the carbon content of the molten steel is targeted at 0.15%, 0.25% or 0.30%. In some embodiments of the invention, the monitored target of the molten steel temperature is 1690 ℃, 1695 ℃, or 1700 ℃. In the invention, the oxygen blowing is stopped after the temperature and the carbon content of the molten steel are monitored to reach the above targets.
The purpose of step S1 is to fully utilize the thermodynamic conditions of high carbon and high temperature to promote the reduction of MnO in the slag into molten steel, thereby increasing the manganese content of the molten steel, but the phosphorus content of the molten steel is relatively high.
Regarding step S2:
in the present invention, after the oxygen blowing is stopped in step S1, the top-blown oxygen lance is used to blow the inert gas, and the carbonaceous reducing agent is added to raise the bottom-blown gas supply strength to 0.08-0.15 m3/(min. ton steel).
The inert gas is preferably nitrogen or argon, more preferably nitrogen. Wherein the conditions for blowing the inert gas by the top-blowing oxygen lance are as follows: the gas supply intensity is 2.5-3.5 m3And/(/ min. ton steel), the lance position of the oxygen lance is 1.5-2 m. In some embodiments of the invention, the intensity of the supplied air is 2.5m3/(min. ton steel), 3.0m3/(min. ton steel), 3.5m3/(min. ton steel). In some embodiments of the invention, the lance position is 1.6-2.0m, 1.5-1.8m, 1.6-1.9 m.
And adding a carbonaceous reducing agent and improving the strength of bottom blowing gas while blowing the gas.
The carbonaceous reducing agent is preferably a reducing agent with a fixed carbon content of more than 90 wt%; more preferably one or more of anthracite, graphite-like and coke. In the invention, the particle size of the carbonaceous reducing agent is preferably 5-15 mm. The dosage of the carbonaceous reducing agent is preferably 0.5-1.5 kg/t steel; in some embodiments of the invention, the amount is 0.5kg/t steel, 1kg/t steel, 1.5kg/t steel.
The lifting bottom blowing air supply intensity is lifted to 0.08-0.15 m3V (min ton steel); in some embodiments of the invention, 0.08m3/(min. ton steel), 0.12m3/(min. ton steel), 0.15m3/(min. ton steel).
According to the invention, the high-manganese low-phosphorus molten steel is directly tapped through the top blowing and bottom blowing treatment until the temperature of the molten steel reaches 1660-1680 ℃ at the end point and the carbon content of the molten steel at the end point is 0.10% -0.15%. In the invention, the carbon content and the temperature of the molten steel are monitored by the sublance, and once the target parameters are reached, tapping is carried out. In some embodiments of the invention, the monitoring target for the end point molten steel carbon content is 0.10%, 0.12%, 0.15%. In some embodiments of the invention, the monitoring target for the end point molten steel temperature is 1670 ℃, 1672 ℃, or 1680 ℃. In the invention, after the temperature and the carbon content of the molten steel are monitored to reach the above targets, bottom blowing is stopped, and the steel is directly tapped.
Wherein the time for the carbon content and the temperature of the molten steel to reach the target end point is 30-60 s, and the inert gas blowing is stopped immediately after the temperature and the carbon content of the molten steel are monitored to reach the target, namely the time for the top inert gas blowing is 30-60 s; the temperature in the furnace can be quickly reduced in the time, and the furnace is strongly stirred, so that the rapid dephosphorization can be realized, and if the degassing and blowing time is too long, manganese is easily oxidized again, thereby influencing the improvement of the manganese content in the end-point molten steel.
According to the invention, after the monitored end point molten steel temperature and carbon content reach the targets, the molten steel is directly tapped without continuing bottom blowing and stirring, so that the purpose of reducing the phosphorus content of the molten steel within a specified time can be realized, and if the bottom blowing and stirring time is prolonged, manganese in the molten steel is oxidized and enters the slag due to the temperature reduction, so that the manganese content of the molten steel is reduced, and therefore, after top blowing is finished and the monitored end point target of the molten steel is monitored, the molten steel is directly tapped.
In the step S2, inert gas is blown by an oxygen lance to rapidly cool, meanwhile, the stirring of a molten pool is enhanced by using the jet flow of the inert gas and the bottom blowing gas flow of the furnace bottom, the progress of the dephosphorization reaction of a steel-slag interface is promoted, the thermodynamic and kinetic conditions of dephosphorization are improved, the dephosphorization effect is improved, and under the kinetic conditions, the carbonaceous reducing agent further promotes the reduction of MnO and FeO in the slag, the manganese content of the molten steel is further improved, and the total iron content TFe of the final slag is reduced.
According to the steelmaking method provided by the invention, the step S1 and the step S2 are combined together and used in the same furnace for smelting, the carbon content of the molten steel in the first step is controlled to be 0.15% -0.30%, the temperature of the molten steel is controlled to be 1681-1700 ℃, and the carbon content and the temperature of the molten steel in the second step are controlled, so that the steel can be tapped at the end point of the converter through high manganese and low phosphorus in the molten steel, the problem that only low manganese steel can be tapped in the prior art for ensuring the dephosphorization effect is solved, and the method is simple to operate and high in economical efficiency.
For a further understanding of the present invention, reference will now be made to the following preferred embodiments of the invention in conjunction with the examples, but it is to be understood that the description is intended to further illustrate the features and advantages of the invention and is not intended to limit the scope of the claims which follow.
In the following examples and comparative examples, the manganese content and phosphorus content of molten steel were measured by fluorescence analysis, and the total iron content of slag was measured by chemical analysis. The components of the manganese ore are TMn: 20% -40%, TFe: 3% -8% of SiO2: 10% -35%, CaO: 5-8%, P is less than or equal to 0.030%, S is less than or equal to 0.30%, and the balance is impurities; purchased from Panzhihua Steel City group, Inc. The particle size of the carbonaceous reducing agent is 5-15 mm. Smelting steel: 45# steel.
Example 1
S1, smelting by using molten iron in a 200t converter of a certain factory, adding 10kg/t of steel with active lime and 15kg/t of steel with high-magnesium lime into the converter after adding the molten iron, and slagging. Then, oxygen blowing by a top-blowing oxygen lance and air supply by bottom blowing are carried out; wherein, the top-blown oxygen lance supplies gasStrength of 3.0m3V (min. ton steel), the lance position of the oxygen lance is 1.2-1.9m, the gas supply intensity of bottom blowing nitrogen is 0.05m3And/or (min. ton steel), the oxygen blowing was stopped when the carbon content of the molten steel was 0.25% and the temperature of the molten steel was 1690 ℃ by monitoring with a sublance.
S2, after the oxygen lance stops blowing oxygen, nitrogen blowing operation is carried out, simultaneously, carbonaceous reducing agent is added, and the bottom blowing gas supply intensity is improved to 0.12m3V (min ton steel); wherein, the conditions of top-blown nitrogen are as follows: air supply intensity is 2.5m3V (min. ton steel), the oxygen lance position is 1.6-2 m; the carbonaceous reducing agent is anthracite, and the addition amount is 1kg/t steel. And directly tapping when the carbon content of the molten steel is 0.15% and the temperature of the molten steel is 1670 ℃ by using a sublance.
The composition of the initial molten iron and the molten steel obtained in step S1 and the final molten steel obtained in step S2, as well as the total iron content of the final slag, were tested and the results are shown in table 1.
TABLE 1 ingredients of the materials in each step of example 1
From the above test results, it can be seen that the manganese content of the molten steel after the first step operation reaches 0.18%, but the phosphorus content is 0.030%, and the manganese content and the phosphorus content of the molten steel are high. After the second step of operation, the manganese content of the molten steel is further increased to 0.23 percent, the phosphorus content is reduced to 0.006 percent, the molten steel with high manganese content and low phosphorus content is successfully smelted by the converter after the method, and the TFe content of the slag is only 15.5 percent.
Example 2
S1, smelting by adopting semi-steel in a 120-ton converter of a certain factory, adding 20 kg/ton steel of active lime and 10 kg/ton steel of high-magnesium lime into the converter after adding the semi-steel, slagging and adding 10 kg/ton steel of manganese ore. Then, oxygen blowing by a top-blowing oxygen lance and air supply by bottom blowing are carried out; wherein the air supply intensity of the top-blown oxygen lance is 3.5m3V (min. ton steel), the lance position of the oxygen lance is 1.4-2.2m, the gas supply intensity of bottom blowing nitrogen is 0.02m3And/or (min. ton steel), the oxygen blowing was stopped when the carbon content of the molten steel was 0.15% and the temperature of the molten steel was 1695 ℃ by monitoring with a sublance.
S2、After the oxygen lance stops blowing oxygen, nitrogen blowing operation is carried out, simultaneously, carbonaceous reducing agent is added, and the bottom blowing gas supply intensity is improved to 0.15m3V (min ton steel); wherein, the conditions of top-blown nitrogen are as follows: air supply intensity of 3.0m3V (min. ton steel), the oxygen lance position is 1.5-1.8 m; the carbonaceous reducing agent is graphite-like, and the adding amount is 1.5kg/t steel. When the carbon content of the molten steel is monitored to be 0.10 percent by using a sublance and the temperature of the molten steel is 1672 ℃, directly tapping.
The composition of the initial molten iron and the molten steel obtained in step S1 and the final molten steel obtained in step S2, as well as the total iron content of the final slag, were tested and the results are shown in table 1.
Table 2 composition of material at each step in example 2
The above examples show that the aim of increasing the manganese content of the end-point molten steel is achieved by reducing manganese ore in the furnace during semisteel smelting due to the low manganese content of the semisteel. By adopting the method, the manganese content of the molten steel reaches 0.15 percent after the first step of operation, but the phosphorus content is 0.020 percent, and the molten steel has high manganese and phosphorus. After the second step of operation, the manganese content of the molten steel is further increased to 0.19 percent, the phosphorus content is reduced to 0.005 percent, and after the method is adopted, the high-manganese and low-phosphorus molten steel is successfully smelted by the converter, and the TFe content of the slag is only 16.2 percent.
According to the embodiment, the method can realize the purpose of smelting high-manganese and low-phosphorus molten steel in the converter no matter molten iron smelting or semi-steel smelting.
Example 3
S1, smelting by adopting molten iron in a 200t converter of a certain factory, adding 30kg/t of steel by active lime and 5kg/t of steel by high-magnesium lime after adding the molten iron into the converter, and slagging. Then, oxygen blowing by a top-blowing oxygen lance and air supply by bottom blowing are carried out; wherein the air supply intensity of the top-blown oxygen lance is 2.5m3V (min. ton steel), the lance position of the oxygen lance is 1.6-2.5m, the gas supply intensity of bottom blowing nitrogen is 0.06m3V (min. ton steel), molten steel carbon content of 0.30% and molten steel temperature were monitored by a sublanceAnd stopping oxygen blowing when the temperature is 1700 ℃.
S2, after the oxygen lance stops blowing oxygen, nitrogen blowing operation is carried out, simultaneously, carbonaceous reducing agent is added, and the bottom blowing gas supply intensity is improved to 0.08m3V (min ton steel); wherein, the conditions of top-blown nitrogen are as follows: air supply intensity of 3.5m3V (min. ton steel), the lance position of the oxygen lance is 1.6-1.9 m; the carbonaceous reducing agent is coke, and the addition amount is 0.5kg/t steel. And (3) directly tapping when the carbon content of the molten steel is 0.12% and the temperature of the molten steel is 1680 ℃ by using a sublance.
The composition of the initial molten iron and the molten steel obtained in step S1 and the final molten steel obtained in step S2 were tested, as well as the total iron content of the final slag, and the results are shown in table 3.
Table 3 composition of material at each step in example 3
From the test results, it can be seen that the manganese content of the molten steel after the first step of operation reaches 0.17%, but the phosphorus content is 0.036%, and the manganese content and the phosphorus content of the molten steel are high. After the second step of operation is adopted, the manganese content of the molten steel is further increased to 0.21 percent, the phosphorus content is reduced to 0.007 percent, the high-manganese and low-phosphorus molten steel is successfully smelted by the converter after the method, and the TFe content of the slag is only 15.7 percent.
Comparative example 1
S1, the procedure of example 1 was repeated, except that the lance was used to monitor the carbon content of molten steel to be 0.05% and the oxygen blowing was stopped at a molten steel temperature of 1720 ℃.
The composition of the initial molten iron and the final molten steel obtained in step S1 and the total iron content of the final slag were measured, and the results are shown in table 4.
Table 4 composition of the material in each step of comparative example 1
Comparative example 2
S1, the procedure of example 1 was repeated, except that the lance was used to monitor the carbon content of molten steel at 0.40% and the oxygen blowing was stopped at a molten steel temperature of 1610 ℃.
S2, conducted as in example 1, except that the nitrogen top-blown gas supply intensity was 5.0m3The air supply intensity of the bottom blowing is improved to 0.30m3And/or (min. ton steel), when the carbon content of the molten steel is monitored by using a sublance to be 0.14% and the temperature of the molten steel is 1650 ℃, directly tapping.
The composition of the initial molten iron and the molten steel obtained in step S1 and the final molten steel obtained in step S2 were tested, and the total iron content of the final slag was determined, as shown in Table 5.
TABLE 5 ingredients of materials in each step of comparative example 2
As can be seen from the above comparative examples 1-2, if the target parameters of the molten steel composition in step S1, the operating parameters in step S2, and the target parameters of the end-point molten steel composition are broken, the increase of the manganese content and the decrease of the phosphorus content of the molten steel are affected, the high-manganese low-phosphorus molten steel cannot be obtained, and the high-manganese low-phosphorus molten steel can be obtained only under the condition parameters of the present invention.
The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (9)
1. A steelmaking method for obtaining high-manganese low-phosphorus molten steel through converter smelting is characterized by comprising the following steps:
s1, after molten iron/semisteel is added into the converter, slagging is carried out, manganese ore is added, then oxygen blowing is carried out by a top-blowing oxygen lance, gas supply is carried out by bottom blowing until the carbon content of molten steel is 0.15-0.30% and the temperature of the molten steel reaches 1681-1700 ℃, and oxygen blowing is stopped;
the gas for bottom blowing gas is inert gas;
s2, blowing inert gas by using a top-blowing oxygen lance, adding a carbonaceous reducing agent, and increasing the gas supply intensity of bottom blowing to 0.08-0.15 m3V (min ton steel); wherein the conditions for blowing the inert gas by the top-blowing oxygen lance are as follows: the gas supply intensity is 2.5-3.5 m3(min. ton steel), the lance position of the oxygen lance is 1.5-2 m; the gas for bottom blowing is inert gas; and tapping until the temperature of the molten steel reaches 1660-1680 ℃ and the carbon content of the molten steel reaches 0.10% -0.15% at the end point to obtain the high-manganese low-phosphorus molten steel.
2. The steel making method according to claim 1, wherein in the step S1, the top-blown lance blows oxygen with a blowing intensity of 2.5 to 3.5m3/(min. ton steel).
3. The steel making method according to claim 1 or 2, wherein in the step S1, the intensity of the bottom-blowing gas is 0.02 to 0.06m3/(min. ton steel).
4. The steelmaking method as claimed in claim 1, wherein in the step S1, the inert gas is nitrogen or argon;
in the step S2, the inert gas is nitrogen or argon.
5. The steelmaking method as claimed in claim 1, wherein in the step S1, the slagging material added in the slagging process is active lime and high-magnesium lime.
6. The steelmaking method according to claim 5, wherein the amount of the active lime is 10 to 30kg/t steel; the dosage of the high-magnesium lime is 5-20 kg/t steel.
7. The steel-making method according to claim 1, wherein in step S2, the carbonaceous reducing agent is a reducing agent having a fixed carbon content of 90 wt% or more.
8. The steelmaking method as claimed in claim 1 or 7, wherein in the step S2, the carbonaceous reducing agent is one or more of anthracite, graphite-like coal and coke;
the particle size of the carbonaceous reducing agent is 5-15 mm;
the dosage of the carbonaceous reducing agent is 0.5-1.5 kg/t steel.
9. The steel-making method according to claim 1, wherein in step S2, the time for blowing the inert gas through the top-blown lance is 30 to 60 seconds;
in the steps S1 and S2, the carbon content and the temperature of molten steel are monitored by using a lance.
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