CN112680565B - By using CO in AOD furnace2Method for smelting high-manganese stainless steel by decarburization - Google Patents
By using CO in AOD furnace2Method for smelting high-manganese stainless steel by decarburization Download PDFInfo
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Abstract
By using CO in AOD furnace2Decarburization smeltingA method for smelting high manganese stainless steel belongs to the field of ferrous metallurgy. The content of manganese in the high-manganese stainless steel is higher than 8 percent, the content of chromium in the high-manganese stainless steel is higher than 10 percent, the AOD smelting method is adopted, molten iron with high manganese and chromium contents can be used as raw materials, a side gun adopts CO2+O2+(N2Or/and Ar) is mixed and blown, and the gas supply pressure is 0.2-1.5 Mpa; the manganese content in the molten iron in the decarburization process can be controlled to be 2.0-8.0%, and the chromium content in the molten iron can be controlled to be 10.0-25.0%. After the decarburization is finished, reducing by adopting a reducing agent, adding lime, fluorite and the like for slag adjustment, and improving the yield of the metal manganese chromium. The invention can realize good manganese and chromium protection effects, a large amount of high-manganese alloy with low price such as high-carbon ferromanganese and the like can be added in the decarburization process, the aim of smelting high-manganese stainless steel by adopting high-manganese high-chromium molten iron at low cost is achieved, the addition amount of electrolytic manganese and other manganese alloys and the consumption of reducing agents in alloying are greatly reduced, and the alloying cost is reduced.
Description
Technical Field
The invention belongs to the field of ferrous metallurgy, and relates to a method for preparing CO in an AOD furnace2The method for smelting the high-manganese stainless steel by decarburization can effectively reduce the production cost of the high-manganese stainless steel.
Background
The high manganese stainless steel is one of important materials widely applied in modern industrial production, and is widely applied to industries such as ultralow temperature storage and transportation, automobiles, railways, building materials, mine wear-resistant parts, large-scale mill liners, metallurgy and the like. In recent years, the steel has become a hot point of attention for many steel enterprises at home and abroad.
However, because manganese is an easily oxidizable element, it is easily oxidized during the smelting process, and manganese is generally only used as a deoxidizer or alloy to be added into molten steel during the molten steel deoxidation and alloying. The manganese content in the high-manganese stainless steel is higher, generally reaches 5-20%, and if electrolytic manganese or metal manganese is added only after the steelmaking decarburization is finished, the addition amount is larger, the influence on steelmaking production temperature control is great, and the production cost is higher.
Disclosure of Invention
The invention aims to provide a method for smelting high-manganese stainless steel in an AOD furnace, which adopts CO2+O2+(N2Or/and Ar) is mixed and blown to realize decarburization and manganese conservation to smelt the high manganese stainless steel.
In order to achieve the purpose, the invention adopts the technical scheme that:
by using CO in AOD furnace2The method for smelting the high-manganese stainless steel by decarburization is characterized by comprising the steps of firstly adding molten iron into an AOD furnace, adding a first batch of lime, and simultaneously blowing oxygen, desiliconizing, decarburizing and heating by adopting a top lance and a side lance; after 10-20 minutes, adding high-chromium raw materials such as high-carbon ferrochrome and the like into the molten iron to form high-chromium molten iron; continuously adopting a top lance and a side lance to simultaneously blow oxygen, decarbonize and raise the temperature; after 5-10 minutes, the top lance continues to blow oxygen for decarburization, and the side lance is changed into CO2+O2Mixed converting in which CO is2The flow rate is 20-30% of the side gun blowing flow rate; removing slag after 5-10 min, adding lime and slag former with high content of magnesium oxide to make% CaO/% SiO in slag2Greater than 2.0 and rendering the slag substantially solid; adding high-carbon ferromanganese to form high-carbon chromium-manganese molten iron, wherein the manganese content in the molten iron is controlled to be 2.0-8.0%; stopping oxygen supply from the top lance, and using CO for the side lance2+O2+(N2Or/and Ar) is mixed and blown, the flow rate of the mixed gas is controlled between 0.5 and 2.3Nm3Min.t, the gas supply pressure is 0.2-1.5 Mpa, and the control of the temperature, the flow and the proportion of the mixed gas in the blowing process is continuously adjusted along with the change of the reaction process; strictly controlling the state of the slag in the decarburization process to ensure that the slag is basically kept in a solid state;reducing by using reducing agents such as high-silicon silicomanganese, ferrosilicon and the like after decarburization is finished, and reducing manganese oxide and chromium oxide in the slag; adding lime, fluorite and the like to adjust slag, so that the slag contains CaO/% SiO2More than 1.6, and the slag has better fluidity, promotes the reduction of chromium manganese oxide in the slag, improves the yield of metal manganese and chromium, and reduces the alloying cost.
Further, after desiliconization and temperature raising, high-carbon ferromanganese and high-manganese alloy with low high-manganese return material price are added into the high-chromium molten iron, so that the manganese content in the molten iron is increased; when adding high-carbon ferromanganese or high-manganese return material, the influence of the added material on the temperature of molten iron must be considered, and the temperature of the added molten iron cannot be lower than the carbon-manganese oxidation conversion temperature; if the addition amount is large, the temperature of the molten iron is lower than the oxidation conversion temperature of carbon and manganese, batch addition can be considered, a part of high-carbon ferromanganese or high-manganese return material is added firstly, mixed gas is adopted for blowing, and a batch of high-carbon ferromanganese or high-manganese return material is added after the temperature is remarkably increased;
oxidation conversion temperature T of C-MnCThe calculation relationship is:
in the formula: [% C]Is the percentage content of C in the molten iron, 10 multiplied by 10-2；TCThe oxidation conversion temperature of carbon manganese, K.
Further, desiliconization and temperature raising are carried out before adding the high manganese alloy, slag is removed after desiliconization and temperature raising, slag with lower alkalinity is removed, and the slag removing efficiency is required to reach more than 70%.
Before adding the high manganese alloy, adding a slag former such as lime, high magnesium oxide and the like into the AOD furnace, and adjusting the slag to ensure that the slag contains CaO/% SiO2Greater than 2.0 and rendering the slag substantially solid; adding slagging agent such as lime and high magnesium oxide into AOD furnace 2-3 times in the subsequent decarburization smelting process, and adjusting the slag to make% CaO/% SiO in the slag2Keeping more than 2.0 to make the slag basically solid.
Further, the composition of the mixed blowing gas is continuously adjusted according to the component change and the temperature change of carbon and alloy in steel in the smelting process, and the specific adjustment strategy is as follows:
calculating P according to equation (2)CO，
In the formula: t is the temperature of the molten steel;
if P isCOGreater than 0.8 x 105Pa; the side lance blows in gas O2：N2(Ar):CO2Controlling the flow ratio to be (2.6-3.8): (0.8-1.2): (0.8-1.2);
if P isCOLess than 0.8 x 105Pa but greater than 0.5X 105Pa; the side lance blows in gas O2：N2(Ar):CO2Controlling the flow ratio to be (1.8-2.6): (1.8-2.2): (0.6-0.8);
if P isCOLess than 0.5X 105Pa but greater than 0.3X 105Pa; the side lance blows in gas O2：N2(Ar):CO2Controlling the flow ratio to be (1.5-2.5): (3.0-4.0): (0.5-0.7);
if P isCOLess than 0.3X 105Pa but greater than 0.2X 105Pa; the side lance blows in gas O2：N2(Ar):CO2Controlling the flow ratio to be (0.8-1.2): (4.0-5.0): (0.3-0.5);
if P isCOLess than 0.2X 105Pa; side lance blowing N2(Ar)。
Furthermore, the smelting temperature in the smelting process is not higher than 1720 ℃.
The method for smelting the high-manganese stainless steel comprises the following specific smelting steps:
step 1: adding molten iron into an AOD furnace, adding a first batch of lime, simultaneously blowing oxygen to perform desilication and decarburization by adopting a top gun and a side gun, and quickly heating for 10-20 minutes;
step 2: adding high-chromium raw materials such as high-carbon ferrochrome and the like into molten iron to form high-chromium molten iron, and simultaneously blowing oxygen for decarburization and quickly raising the temperature by adopting a top lance and a side lance for 5-10 minutes;
and step 3: the top lance continuously blows oxygen for decarburization, and the side lance is changed into CO2+O2Mixed converting in which CO is2The flow rate is 20-30% of the side gun blowing flow rate; blowing for 5-10 minutes;
and 4, step 4: removing slag, adding slag-forming materials such as lime and high magnesium oxide to make the slag contain CaO/% SiO2Greater than 2.0 and rendering the slag substantially solid; adding high-carbon ferromanganese to form high-carbon chromium-manganese molten iron, wherein the manganese content in the molten iron is controlled to be 2.0-8.0%;
and 5: stopping oxygen supply from the top lance, and using CO for the side lance2+O2+(N2Or/and Ar) is mixed and blown, the flow rate of the mixed gas is controlled between 0.5 and 2.3Nm3Min.t, the gas supply pressure is 0.2-1.5 Mpa, and the control of the temperature, the flow and the proportion of the mixed gas in the blowing process is continuously adjusted along with the change of the reaction process;
step 6: adding slag-making materials such as lime, high magnesium oxide and the like according to the components of the molten steel, and strictly controlling the state of the slag in the decarburization process to ensure that the slag is basically solid;
and 7: reducing by using reducing agents such as high-silicon silicomanganese, ferrosilicon, aluminum and the like after decarburization is finished, and reducing manganese oxide and chromium oxide in the slag;
and 8: adding lime, fluorite and the like to adjust slag, so that the slag contains CaO/% SiO2More than 1.6, and the slag has better fluidity, promotes the reduction of chromium manganese oxide in the slag, and improves the yield of metal manganese and chromium;
and step 9: adding manganese metal and the like for alloying according to the component requirements of the steel grade;
step 10: and (6) tapping.
The invention can realize good manganese and chromium protection effects while desiliconizing and decarbonizing, and has the following advantages compared with the prior art: (1) before decarburization begins, slag alkalinity is effectively controlled through slag skimming treatment, the inhibition effect of too low slag alkalinity and too high manganese oxide content in slag on molten steel decarburization is relieved, and the reduction of manganese and chromium yield in long-time decarburization smelting is avoided; (2) blowing CO in the decarbonization process2+O2+(N2Or/and Ar) mixed gas, further reducing CO partial pressure, and adopting mixed gas to dynamically adjustThe strategy comprehensively improves the effects of manganese and chromium protection in decarburization; and (3) adding a large amount of high-manganese alloy with low price such as high-carbon ferromanganese and the like in the decarburization process, achieving the aim of smelting high-manganese stainless steel at low cost by adopting high-manganese high-chromium molten iron, greatly reducing the addition of electrolytic manganese and other manganese alloys and the consumption of reducing agents in alloying and reducing the alloying cost.
Detailed Description
Example 1:
60 tons of molten iron is added into an 80-ton AOD furnace, the temperature of the molten iron is 1345 ℃, the carbon content of the molten iron is 3.2 percent, the manganese content is 0.96 percent, and the chromium content is 3.8 percent.
Adding lime 3 tons during heating, desiliconizing and decarbonizing, simultaneously blowing oxygen by a top lance side lance to heat, desiliconizing and decarbonizing, wherein the top lance is 4200Nm3Side lance 4500 Nm/h3Blowing oxygen for 15 minutes;
adding 16.4 tons of high-carbon ferrochrome, simultaneously blowing oxygen by a top lance side lance to raise the temperature, desiliconizing and decarbonizing, wherein 4200Nm of the top lance is used3Side lance 4500 Nm/h3Blowing oxygen for 5 minutes;
oxygen blowing is continued with the top lance at a flow rate of 4200Nm3H, changing side lance to CO2+O2Mixed blowing at a flow rate of 4500Nm3The flow rate of carbon dioxide is 30 percent of the total blowing amount of the side lance, and the blowing lasts for 10 minutes;
stopping blowing, and skimming the slag, wherein the skimming rate reaches 80 percent, the temperature of the molten steel is 1545 ℃, the carbon content is 2.2 percent, the manganese content is 0.46 percent, and the chromium content is 13.5 percent.
And adding lime into the AOD furnace, wherein the adding amount of the lime is 3 tons, the adding amount of the waste magnesia carbon bricks is 0.3 ton, the maximum particle size of the waste magnesia carbon bricks is less than 5mm, and the adding amount of the high-carbon ferromanganese is 3 tons. Stopping blowing oxygen by the top lance, blowing CO by the side lance2+O2+N2Mixed converting is carried out, the flow rates of oxygen, nitrogen and carbon dioxide are respectively 3500Nm3/h、 1000Nm3/h、1000Nm3Blowing for 10 minutes, adding 1 ton of lime and 0.1 ton of waste magnesia carbon bricks, wherein the maximum particle size of the waste magnesia carbon bricks is less than 5 mm; the flow rates of oxygen, nitrogen and carbon dioxide are respectively adjusted to 2500Nm3/h、2000Nm3/h、800Nm3Blowing for 8 minutes, adding stone1 ton of ash and 0.1 ton of waste magnesia carbon bricks; the flow rates of oxygen, nitrogen and carbon dioxide are respectively adjusted to 1800Nm3/h、3500Nm3/h、600 Nm3Blowing for 6 minutes; the flow rates of oxygen, nitrogen and carbon dioxide are 1200Nm respectively3/h、4500Nm3/h、 400Nm3Blowing for 5 minutes. The slag is kept in a dry and thick state in the whole process.
Stopping blowing, wherein the temperature of the molten steel is 1633 ℃, the carbon content is 0.17%, the manganese content is 3.3%, and the chromium content is 13.8%.
Adding silicon-manganese alloy for reduction, wherein the addition of high-silicon ferromanganese is 3.1 tons, and the addition of ordinary silicon ferromanganese is 1.5 tons; 1.5 tons of fluorite is added to ensure good fluidity of the slag, and nitrogen is blown into the slag by a side gun for 10 minutes.
Adding electrolytic manganese to adjust the alloy components, wherein the adding amount of the electrolytic manganese is 1.6 tons.
The AOD furnace tapping temperature is 1580 ℃, the carbon content is 0.14%, the manganese content is 9.0%, and the chromium content is 13.2%.
Example 2:
56 tons of molten iron is added into an 80-ton AOD furnace, the temperature of the molten iron is 1323 ℃, the carbon content of the molten iron is 3.2%, the manganese content is 1.0%, and the chromium content is 3.8%.
2.0 tons of lime is added in the heating desiliconization and decarbonization process, a top lance side lance is adopted to simultaneously blow oxygen to heat up, desiliconization and decarbonization, and the top lance is 4200Nm3Side lance 4500 Nm/h3Blowing oxygen for 15 minutes;
adding 25 tons of high-carbon ferrochrome, simultaneously blowing oxygen by a top lance side lance to raise the temperature for desiliconization and decarburization, wherein the top lance is 4200Nm3Side lance 4500 Nm/h3Blowing oxygen for 10 minutes;
oxygen blowing is continued with the top lance at a flow rate of 4200Nm3H, changing side lance to CO2+O2Mixed blowing at a flow rate of 4500Nm3The flow rate of carbon dioxide is 20 percent of the total blowing amount of the side lance, and the blowing is carried out for 15 minutes;
stopping blowing, and skimming the slag until the slag skimming rate reaches 80%, wherein the molten steel temperature is 1538 ℃, the carbon content is 3.8%, the manganese content is 0.46%, and the chromium content is 19.8%.
2.5 tons of lime is added into the AOD furnace,0.4 ton of waste magnesia carbon bricks, the maximum particle size of the waste magnesia carbon bricks is less than 5mm, the addition of high-carbon ferromanganese is 3.1 tons, the top lance is stopped to blow oxygen, and the side lance blows CO2+O2+N2Mixed converting is carried out, the flow rates of oxygen, nitrogen and carbon dioxide are respectively 3500Nm3/h、1000Nm3/h、 1000Nm3Blowing for 10 minutes, adding 1 ton of lime and 0.1 ton of waste magnesia carbon bricks; the flow rates of oxygen, nitrogen and carbon dioxide are 2400Nm respectively3/h、2000Nm3/h、800Nm3Blowing for 10 minutes, adding 1 ton of lime and 0.1 ton of waste magnesia carbon bricks, wherein the maximum particle size of the waste magnesia carbon bricks is less than 5 mm; the flow rates of oxygen, nitrogen and carbon dioxide are 1800Nm respectively3/h、3500Nm3/h、600Nm3Blowing for 8 minutes; the flow rates of oxygen, nitrogen and carbon dioxide are 1200Nm respectively3/h、4500Nm3/h、400Nm3Blowing for 6 minutes. The slag is kept in a dry and thick state in the whole process.
Blowing is stopped, and the temperature of the molten steel is 1676 ℃, the carbon content is 0.16%, the manganese content is 3.4%, and the chromium content is 19.0%.
Stopping oxygen blowing, adding silicon-manganese alloy for reduction, wherein the addition of high-silicon ferromanganese is 3.2 tons, and the addition of ordinary silicon ferromanganese is 1.5 tons; 1.7 tons of fluorite is added to ensure good fluidity of the slag, and nitrogen is blown into the slag by a side gun for 10 minutes.
Electrolytic manganese is added to adjust the alloy components, and the adding amount of the electrolytic manganese is 1.2 tons.
The AOD secondary tapping temperature is 1560 ℃, the carbon content is 0.12%, the manganese content is 8.1%, and the chromium content is 18.5%.
Example 3:
60 tons of molten iron is added into an 80-ton AOD furnace, the temperature of the molten iron is 1340 ℃, the carbon content of the molten iron is 3.3 percent, the manganese content is 0.95 percent, and the chromium content is 3.8 percent.
Adding lime 3.0 ton in the heating desiliconization and decarbonization process, simultaneously blowing oxygen by a top lance side lance to heat up and desiliconize and decarbonize, wherein the top lance is 4200Nm3Side lance 4500 Nm/h3Blowing oxygen for 14 minutes;
adding 16.4 tons of high-carbon ferrochrome, and simultaneously blowing oxygen by a top lance and a side lance to raise the temperature for desiliconization and decarburizationTop lance 4200Nm3Side lance 4500 Nm/h3Blowing oxygen for 5 minutes;
oxygen blowing is continued with the top lance at a flow rate of 4200Nm3H, changing side lance to CO2+O2Mixed blowing at a flow rate of 4500Nm3The flow rate of carbon dioxide is 30 percent of the total blowing amount of the side lance, and the blowing lasts for 10 minutes;
stopping blowing, and skimming the slag until the skimming rate reaches 80%, wherein the temperature of the molten steel is 1580 ℃, the carbon content is 2.3%, the manganese content is 0.38%, and the chromium content is 14.3%.
Adding 4 tons of lime and 0.5 ton of waste magnesia carbon bricks into the AOD furnace, wherein the maximum particle size of the waste magnesia carbon bricks is less than 5mm, and the adding amount of high-carbon ferromanganese is 4 tons. Stopping blowing oxygen by the top lance, blowing CO by the side lance2+O2+N2Mixed blowing is carried out, the flow rates of oxygen, nitrogen and carbon dioxide are 3600Nm respectively3/h、1000Nm3/h、1000 Nm3Blowing for 12 minutes, adding 1 ton of lime and 0.15 ton of waste magnesia carbon bricks; the flow rates of oxygen, nitrogen and carbon dioxide are 2500Nm respectively3/h、2000Nm3/h、800Nm3Blowing for 10 minutes, adding 1 ton of lime and 0.15 ton of waste magnesia carbon bricks, wherein the maximum particle size of the waste magnesia carbon bricks is less than 5 mm; the flow rates of oxygen, nitrogen and carbon dioxide are 1800Nm respectively3/h、3500Nm3/h、600Nm3Blowing for 9 minutes; the flow rates of oxygen, nitrogen and carbon dioxide are 1200Nm respectively3/h、4500Nm3/h、400Nm3H, converting for 9 minutes. The slag is kept in a dry and thick state in the whole process.
Blowing is stopped, and the temperature of the molten steel is 1650 ℃, the carbon content is 0.16 percent, the manganese content is 4.3 percent, and the chromium content is 13.2 percent.
Adding silicon-manganese alloy for reduction, wherein the addition of high-silicon ferromanganese is 3.2 tons, and the addition of ordinary silicon ferromanganese is 1.6 tons; 1.6 tons of fluorite is added to ensure good fluidity of the slag, and nitrogen is blown into the slag by a side gun for 10 minutes.
And adding metal manganese to adjust the alloy components, wherein the addition amount of the metal manganese is 0.8 ton.
The AOD secondary tapping temperature is 1550 ℃, the carbon content is 0.13%, the manganese content is 9.1%, and the chromium content is 13.3%.
Example 4:
56 tons of molten iron is added into an 80-ton AOD furnace, the temperature of the molten iron is 1325 ℃, the carbon content of the molten iron is 3.2 percent, the manganese content is 0.97 percent, and the chromium content is 3.7 percent.
2.5 tons of lime is added in the heating desiliconization and decarbonization process, a top lance side lance is adopted to simultaneously blow oxygen to heat up, desiliconize and decarbonize, and the top lance is 4200Nm3Side lance 4500 Nm/h3Blowing oxygen for 16 minutes;
adding 20.2 tons of high-carbon ferrochrome, simultaneously blowing oxygen by a top lance side lance to heat up, desiliconizing and decarburizing, wherein the top lance is 4200Nm3Side lance 4500 Nm/h3Blowing oxygen for 8 minutes;
oxygen blowing is continued with the top lance at a flow rate of 4200Nm3H, changing side lance to CO2+O2Mixed blowing at a flow rate of 4500Nm3The flow rate of carbon dioxide is 25 percent of the total blowing amount of the side lance, and the blowing lasts for 12 minutes;
stopping blowing, and skimming the slag until the skimming rate reaches 80%, wherein the temperature of the molten steel is 1580 ℃, the carbon content is 2.3%, the manganese content is 0.37%, and the chromium content is 17.1%.
Adding 4 tons of lime and 0.5 ton of waste magnesia carbon bricks into the AOD furnace, wherein the maximum particle size of the waste magnesia carbon bricks is less than 5mm, and the adding amount of high-carbon ferromanganese is 4.1 tons. Stopping blowing oxygen by the top lance, blowing CO by the side lance2+O2+N2Mixed blowing is carried out, the flow rates of oxygen, nitrogen and carbon dioxide are 3600Nm respectively3/h、1000Nm3/h、 1000Nm3Blowing for 12 minutes, adding 1 ton of lime and 0.15 ton of waste magnesia carbon bricks; the flow rates of oxygen, nitrogen and carbon dioxide are 2500Nm respectively3/h、2000Nm3/h、800Nm3Blowing for 11 minutes, adding 1 ton of lime and 0.15 ton of waste magnesia carbon bricks, wherein the maximum particle size of the waste magnesia carbon bricks is less than 5 mm; the flow rates of oxygen, nitrogen and carbon dioxide are 1800Nm respectively3/h、3500Nm3/h、600Nm3Blowing for 10 minutes; the flow rates of oxygen, nitrogen and carbon dioxide are 1200Nm respectively3/h、4500Nm3/h、400Nm3H, converting for 9 minutes. The slag is kept in a dry and thick state in the whole process.
Blowing is stopped, and the temperature of the molten steel is 1650 ℃, the carbon content is 0.16 percent, the manganese content is 4.4 percent, and the chromium content is 16.6 percent.
Adding silicon-manganese alloy for reduction, wherein the addition of high-silicon ferromanganese is 3.1, and the addition of ordinary silicon ferromanganese is 1.6 tons; 1.7 tons of fluorite is added to ensure good fluidity of the slag, and nitrogen is blown into the slag by a side gun for 10 minutes.
And adding metal manganese to adjust the alloy components, wherein the addition amount of the metal manganese is 0.8 ton.
The AOD secondary tapping temperature is 1550 ℃, the carbon content is 0.13%, the manganese content is 8.8%, and the chromium content is 15.6%.
Example 5:
60 tons of molten iron is added into an 80-ton AOD furnace, the temperature of the molten iron is 1320 ℃, the carbon content of the molten iron is 3.3 percent, the manganese content is 0.96 percent, and the chromium content is 3.5 percent.
2.0 tons of lime is added in the heating desiliconization and decarbonization process, a top lance side lance is adopted to simultaneously blow oxygen to heat up, desiliconization and decarbonization, and the top lance is 4200Nm3Side lance 4500 Nm/h3Blowing oxygen for 14 minutes;
adding 16.8 tons of high-carbon ferrochrome, simultaneously blowing oxygen by a top lance side lance to raise the temperature, desiliconizing and decarbonizing, wherein 4200Nm of the top lance is used3Side lance 4500 Nm/h3Blowing oxygen for 5 minutes;
oxygen blowing is continued with the top lance at a flow rate of 4200Nm3H, changing side lance to CO2+O2Mixed blowing at a flow rate of 4500Nm3The flow rate of carbon dioxide is 20 percent of the total blowing amount of the side lance, and the blowing is carried out for 9 minutes;
stopping blowing, and skimming the slag until the skimming rate reaches 80%, wherein the temperature of the molten steel is 1580 ℃, the carbon content is 2.3%, the manganese content is 0.37%, and the chromium content is 14.1%.
5 tons of lime and 0.6 ton of waste magnesia carbon bricks are added into the AOD furnace, the maximum particle size of the waste magnesia carbon bricks is less than 5mm, and the addition amount of the high-carbon ferromanganese is 5 tons. Stopping blowing oxygen by the top lance, blowing CO by the side lance2+O2+N2Mixed blowing is carried out, the flow rates of oxygen, nitrogen and carbon dioxide are 3400Nm respectively3/h、1000Nm3/h、1000 Nm3Blowing for 15 minutes, adding 1 ton of lime and waste magnesia carbonBrick 0.2 ton; the flow rates of oxygen, nitrogen and carbon dioxide are 2500Nm respectively3/h、2000Nm3/h、800Nm3Blowing for 13 minutes, adding 1 ton of lime and 0.2 ton of waste magnesia carbon bricks, wherein the maximum particle size of the waste magnesia carbon bricks is less than 5 mm; the flow rates of oxygen, nitrogen and carbon dioxide are 1800Nm respectively3/h、3500Nm3/h、600Nm3Blowing for 11 minutes; the flow rates of oxygen, nitrogen and carbon dioxide are 1200Nm respectively3/h、4500Nm3/h、400Nm3Blowing for 10 minutes. The slag is kept in a dry and thick state in the whole process.
Blowing is stopped, and the temperature of the molten steel is 1650 ℃, the carbon content is 0.16 percent, the manganese content is 5.3 percent, and the chromium content is 12.9 percent.
Adding silicon-manganese alloy for reduction, wherein the addition of high-silicon ferromanganese is 3 tons, and the addition of ordinary silicon ferromanganese is 1.2 tons; 1.7 tons of fluorite is added to ensure good fluidity of the slag, and nitrogen is blown into the slag by a side gun for 10 minutes.
And adding metal manganese to adjust the alloy components, wherein the addition amount of the metal manganese is 0.5 ton.
The AOD secondary tapping temperature is 1550 ℃, the carbon content is 0.13%, the manganese content is 9.1%, and the chromium content is 13.3%.
Claims (5)
1. By using CO in AOD furnace2The method for smelting the high-manganese stainless steel by decarburization is characterized by comprising the steps of firstly adding molten iron into an AOD furnace, adding a first batch of lime, and simultaneously blowing oxygen, desiliconizing, decarburizing and heating by adopting a top lance and a side lance; after 10-20 minutes, adding a high-carbon ferrochrome high-chromium raw material into molten iron to form high-chromium molten iron; continuously adopting a top lance and a side lance to simultaneously blow oxygen, decarbonize and raise the temperature; after 5-10 minutes, the top lance continues to blow oxygen for decarburization, and the side lance is changed into a side lance
Mixed converting in which
The flow rate is 20-30% of the side gun blowing flow rate; removing slag after 5-10 min, adding lime and high-magnesia content slag formerIn the slag of the furnace
Greater than 2.0 and rendering the slag substantially solid; adding high-carbon ferromanganese to form high-carbon chromium-manganese molten iron, wherein the manganese content in the molten iron is controlled to be 2.0-8.0%; stopping oxygen supply from the top lance, side lances
Or/and
the mixed gas is controlled to be in
The air supply pressure is 0.2-1.5
The control of the temperature, the flow rate and the proportion of the mixed gas in the blowing process is continuously adjusted along with the change of the reaction process; strictly controlling the state of the slag in the decarburization process to ensure that the slag is basically kept in a solid state; reducing by adopting a silicomanganese and ferrosilicon reducing agent after the decarbonization is finished, and reducing manganese oxide and chromium oxide in the slag; adding lime and fluorite to adjust slag to the slag
More than 1.6, ensures that the slag has better fluidity, promotes the reduction of chromium-manganese oxide in the slag, improves the yield of metal manganese and chromium, and reduces the alloying cost;
after desiliconization and temperature raising, adding high-carbon ferromanganese or high-manganese return material or low-cost high-manganese alloy into the high-chromium molten iron to increase the manganese content in the molten iron; when adding high-carbon ferromanganese or high-manganese return material, the influence of the added material on the temperature of molten iron must be considered, and the temperature of the added molten iron cannot be lower than the carbon-manganese oxidation conversion temperature; if the addition amount is large, the temperature of the molten iron is lower than the oxidation conversion temperature of carbon and manganese, batch addition can be considered, a part of high-carbon ferromanganese or high-manganese return material is added firstly, mixed gas is adopted for blowing, and a batch of high-carbon ferromanganese or high-manganese return material is added after the temperature is remarkably increased;
oxidation conversion temperature of carbon and manganese
The calculation relationship is:
in the formula:
is the percentage content of C in the molten iron,
；
the temperature of the oxidation conversion of the carbon and the manganese,
。
2. the method for smelting the high-manganese stainless steel according to claim 1, wherein desiliconization and temperature raising are carried out before adding the high-manganese alloy, slag is removed after desiliconization and temperature raising, and slag removal efficiency is required to be more than 70%.
3. The method for smelting high-manganese stainless steel according to claim 1, wherein lime and a high-magnesia slag former are added into the AOD furnace before the high-manganese alloy is added, and the slag is adjusted to be in the slag
Greater than 2.0 and rendering the slag substantially solid; the subsequent decarburization smelting process is divided into 2 to 3 timesAdding lime and high-magnesia slag former into the AOD furnace, and adjusting the slag to ensure that the slag is in
Keeping more than 2.0 to make the slag basically solid.
4. The method for smelting the high-manganese stainless steel according to claim 1, wherein the composition of the mixed blowing gas is continuously adjusted according to the component change and the temperature change of carbon and alloy in the steel in the smelting process, and the specific adjustment strategy is as follows:
according to equation (2)
，
In the formula:
the temperature of the molten steel is;
if it is not
Is greater than
(ii) a The side lance blows into the gas
：
Or/and
controlling the flow ratio to be (2.6-3.8): (0.8-1.2): (0.8-1.2）；
If it is not
Is less than
But greater than
(ii) a The side lance blows into the gas
：
Or/and
controlling the flow ratio to be (1.8-2.6): (1.8-2.2): (0.6-0.8);
if it is not
Is less than
But greater than
(ii) a The side lance blows into the gas
：
Or/and
the flow ratio is controlled to be (1.5-2.5)：（3.0-4.0）：（0.5-0.7）；
If it is not
Is less than
But greater than
(ii) a The side lance blows into the gas
：
Or/and
controlling the flow ratio to be (0.8-1.2): (4.0-5.0): (0.3-0.5);
if it is not
Is less than
(ii) a Side lance insufflation
Or/and
。
5. the method for smelting the high manganese stainless steel according to claim 1, wherein the smelting temperature is not higher than 1720 ℃ in the smelting process.
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