A low-cost production method for microalloyed construction steel

Abstract

The invention provides a low-cost production method for micro-alloyed steel for construction, which specifically comprises the following steps: A1, performing manganese alloying, silicon partial alloying, and adding vanadium slag during steel tapping in an electric furnace; A2, adding ferrosilicon alloy in an LF furnace; A3, slag making and heating in the LF furnace; A4, refining and making white slag in the LF furnace; A5, after the treatment in the LF refining furnace is completed, vanadium-containing molten steel is obtained, and continuous casting is subsequently performed, wherein the vanadium slag comprises, by weight percentage, V2O5 content of 10-13%, SiO2 of 10-20%, TiO2 of 10-20%, MnO of 5-10%, P2O5 content of less than 0.10%, TFe content of 30-40%, and the particle size of the vanadium slag of 10-100 mm. The components of the molten steel at the end of the electric furnace include: C content of 0.05-0.1%, Si content of 0.002-0.006%, and Mn content of 0.02-0.06%. In actual use, the present invention uses vanadium slag containing a certain V2O5 content to micro-alloy vanadium in molten steel discharged from an electric furnace, thereby solving the technical problem of high cost of using vanadium-nitrogen alloy or 50 vanadium iron to increase vanadium in reinforced steel.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, and in particular to a low-cost production method of micro-alloyed steel for construction. Background Art

[0002] Reducing costs is easier said than done, but if enterprises want to get out of trouble and develop against the trend, reducing costs is a way. Steelmaking costs are mainly composed of three parts: variable costs, fixed costs and comprehensive recycling. Among them, variable costs refer to items whose total consumption rises and falls with changes in production, including: steel material consumption, alloy materials, auxiliary materials, refractory materials, power, etc. Based on the three elements of steelmaking costs, our company carefully formulates cost-reducing process and technical measures, relying on technological innovation to promote cost reduction and efficiency improvement in all directions.

[0003] The steel industry has a long industrial chain and covers a wide range of areas. Faced with difficulties such as insufficient recovery of traditional market demand, increasing periodic supply and demand contradictions, and declining industry profitability, the majority of steel companies are working hard to improve profitability and promote cost reduction and efficiency improvement. Alloy costs account for about 20% of the cost of electric furnace smelting. With the abnormal fluctuations in the price of precious alloys and the high start of spot prices, the cost of electric furnace smelting has also increased. Therefore, reducing alloy costs has also become one of the key factors in reducing costs and increasing efficiency of electric furnaces.

[0004] The steelmaking process in the prior art has the defect of high process cost. Summary of the invention

[0005] The object of the present invention is to provide a low-cost production method of micro-alloyed construction steel, which has the advantage of reducing process costs.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A low-cost production method for microalloyed construction steel comprises the following steps:

[0008] A1, manganese alloying, silicon partial alloying, and vanadium slag addition during steelmaking in an electric furnace;

[0009] A2, LF furnace with ferrosilicon alloy added;

[0010] A3, LF furnace slag making and heating;

[0011] A4, LF furnace refining to produce white slag;

[0012] A5, LF refining furnace treatment is completed, vanadium-containing molten steel is obtained, and then continuous casting is carried out.

[0013] The vanadium slag includes, by weight percentage, 10-13% V2O5, 10-20% SiO2, 10-20% TiO2, 5-10% MnO, less than 0.10% P2O5, 30-40% TFe, and the particle size of the vanadium slag is 10-100 mm.

[0014] Among them, the final molten steel composition of the electric furnace is: C content 0.05-0.1%, Si content 0.002-0.006%, Mn content 0.02-0.06%.

[0015] Preferably, the ladle containing molten steel tapped from the electric furnace in step A1 is in a ladle baking preheating state before being transported to the tapping position, and scrap steel is loaded in the ladle, and the scrap steel temperature in the ladle is 900-1100°C.

[0016] Furthermore, the vanadium slag is transported to the alloy material silo behind the electric furnace, and during the steel-making process, 3.5 to 7 kg / ton of steel of vanadium slag is added manually into the chute behind the furnace and aligned with the steel flow.

[0017] In the A1 step, during the steel tapping process, silicon-manganese alloy is added along with the steel flow, with Si content of 15-25%, manganese content of 65-75%, and the rest of iron, silicon-manganese alloy 12-13kg / ton of steel;

[0018] After the silicon-manganese alloy is added, stir with argon for 4-7 minutes, with an argon flow rate of 100-150m³ / hour and an argon pressure of 0.8-1.2MPa. The ladle is then transported to the LF furnace.

[0019] Furthermore, in step A2, after LF enters the station, 0.35-0.45 kg of ferrosilicon is added per ton of steel, of which the Si content is 70-80%, and the rest is TFe, 100-200 kg of carbon powder, and the carbon content is >90%. At the same time, 6-8 kg of lime is added per ton of steel and heated for 5 minutes. At this time, the temperature is 1520-1540°C. Sampling and analysis of the molten steel composition show that the carbon content is 0.14-0.16%, the silicon content is 0.13-0.15%, and the vanadium content is 0.012-0.016%.

[0020] Preferably, in step A3, heating is continued, 5-7 kg / ton of lime is added to make "white slag", and the remaining ferrosilicon alloy required by the steel grade is added. The temperature of the molten steel is 1570-1610°C after refining. At this time, the main components of the molten steel are as follows: C content 0.22-0.25%, Si content 0.29-0.34%, Mn content 0.95-1.1%, P content <0.02%, and S content <0.03%.

[0021] Furthermore, in steps A2-A5, argon is blown from the bottom throughout the LF refining process. The bottom blowing system consists of a gas and a blowing pipeline. The gas is nitrogen or argon. The bottom blowing gas flow rate is 50-150m³ / hour. The blowing pipeline is connected to the air-permeable bricks at the bottom of the electric furnace through a pipe. The number of bottom blowing air-permeable bricks is 1-3.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] In actual use, the present invention uses vanadium slag containing a certain V2O5 content to carry out vanadium micro-alloying in molten steel discharged from an electric furnace, thereby solving the technical problem of high cost of using vanadium-nitrogen alloy or 50 vanadium iron to increase vanadium in reinforced steel; the present invention aims at large-scale application and solves the problems of unstable alloy yield by optimizing the process and other measures. DETAILED DESCRIPTION

[0024] Embodiment 1

[0025] This embodiment discloses a low-cost production method of microalloyed construction steel, which specifically includes the following steps:

[0026] A1, manganese alloying, silicon partial alloying, and vanadium slag addition during steelmaking in an electric furnace;

[0027] A2, LF furnace with ferrosilicon alloy added;

[0028] A3, LF furnace slag making and heating;

[0029] A4, LF furnace refining to produce white slag;

[0030] A5, LF refining furnace treatment is completed, vanadium-containing molten steel is obtained, and then continuous casting is carried out.

[0031] The vanadium slag includes, by weight percentage: V2O5 content of 10-13%, SiO2 of 10-20%, TiO2 of 10-20%, MnO of 5-10%, P2O5 content of less than 0.10%, TFe content of 30-40%, and the remainder is impurities. The particle size of the vanadium slag is 10-100mm.

[0032] Among them, the final molten steel composition of the electric furnace is: C content 0.05-0.1%, Si content 0.002-0.006%, Mn content 0.02-0.06%.

[0033] Preferably, the ladle containing the molten steel tapped from the electric furnace in step A1 is in a ladle baking preheating state before being transported to the tapping position, and the ladle is filled with scrap steel, and the scrap steel temperature in the ladle is 900-1100° C.;

[0034] Better use of heat energy to preheat some scrap steel while baking the ladle;

[0035] Furthermore, the vanadium slag is transported to the alloy material bin behind the electric furnace, and the steel-out process is done by manually adding vanadium slag at 3.5-7 kg / ton of steel to the steel flow at the chute behind the furnace. The purpose of adding vanadium slag to the steel flow is to use the impact of the steel flow to make the vanadium slag melt better.

[0036] In the A1 step, during the steel tapping process, silicon-manganese alloy is added along with the steel flow, with Si content of 15-25%, manganese content of 65-75%, and the rest of iron, silicon-manganese alloy 12-13kg / ton of steel;

[0037] After the silicon-manganese alloy is added, stir with argon for 4-7 minutes, with an argon flow rate of 100-150m³ / hour and an argon pressure of 0.8-1.2MPa. The ladle is then transported to the LF furnace.

[0038] Furthermore, in step A2, after LF enters the station, 0.35-0.45 kg of ferrosilicon is added per ton of steel, of which the Si content is 70-80%, and the rest is TFe, 100-200 kg of carbon powder, and the carbon content is >90%. At the same time, 6-8 kg of lime is added per ton of steel and heated for 5 minutes. At this time, the temperature is 1520-1540°C. Sampling and analysis of the molten steel composition show that the carbon content is 0.14-0.16%, the silicon content is 0.13-0.15%, and the vanadium content is 0.012-0.016%.

[0039] Among them, ferrosilicon is added once according to the composition of molten steel entering the station, and only one addition can meet the composition requirements of the steel grade; carbon powder is 100-200 kg / furnace, which is equivalent to 0.4~1.5 kg / ton of steel;

[0040] Preferably, in step A3, heating is continued, 5-7 kg / ton of lime is added to make "white slag", and the remaining ferrosilicon alloy required by the steel grade is added. The temperature of the molten steel is 1570-1610°C after refining. At this time, the main components of the molten steel are as follows: C content 0.22-0.25%, Si content 0.29-0.34%, Mn content 0.95-1.1%, P content <0.02%, and S content <0.03%.

[0041] In step 3, the remaining ferrosilicon alloy required by the steel grade is added. Generally, it is supplemented when the subsequent components are insufficient. The specific amount added is confirmed based on the measured value, and generally it is added until the requirements are met.

[0042] Furthermore, in steps A2-A5, argon is blown from the bottom throughout the LF refining process. The bottom blowing system consists of a gas and a blowing pipeline. The gas is nitrogen or argon. The bottom blowing gas flow rate is 50-150m³ / hour. The blowing pipeline is connected to the air-permeable bricks at the bottom of the electric furnace through a pipe. The number of bottom blowing air-permeable bricks is 1-3.

[0043] In order to facilitate those skilled in the art to further understand the present invention, the present invention is further described below with reference to specific cases.

[0044] Case 1

[0045] After being blown in an electric furnace to the final steel composition, the steel output is 140 tons, and the final steel composition is: C content 0.07%, Si content 0.003%, Mn content 0.03%.

[0046] The ladle that holds the molten steel from the electric furnace is in a ladle baking and preheating state before being transported to the steel-tapping position. The ladle is loaded with 15 tons of scrap steel, and the temperature of the scrap steel in the ladle is 1000℃.

[0047] During the steel-making process, qualified vanadium slag that meets the requirements is added manually in the chute behind the furnace to the steel flow of the steel-making process. 600 kg of vanadium slag (i.e. 3.63 kg / ton of steel) is added. The composition of the vanadium slag is 11% V2O5, 15% SiO2, 14% TiO2, 7% MnO, less than 0.10% P2O5, 33% TFe, and the particle size of the vanadium slag is 10-100mm. At the same time, 13 kg / ton of steel is added with silicon-manganese alloy. After the addition of vanadium slag and silicon-manganese alloy, argon is stirred for 5 minutes, the argon flow rate is 120m³ / hour, and the argon pressure is 1.0MPa. The molten steel ladle is then transported to the LF refining process, and argon is blown at the bottom throughout the LF refining process. After LF enters the station, 0.4kg of ferrosilicon (Si content 70-80%, the rest TFe), 150kg of carbon powder (carbon content>90%), and 1000kg of lime are added at the same time. Heat for 5 minutes. At this time, the temperature is 1530℃. Sample analysis of the molten steel shows that the carbon content is 0.15%, the silicon content is 0.14%, and the vanadium content is 0.013%. Continue heating, add 900kg of lime (5-7kg per ton of steel) to make "white slag", add the remaining ferrosilicon and other alloys required by the steel grade, and the temperature of the molten steel is 1590℃ after refining. At this time, the main components of the molten steel are as follows: C content 0.23%, Si content 0.31%, Mn content 1.0%, P content <0.02%, S content <0.03%. After the above process steps are completed, the target vanadium-containing molten steel is obtained, and continuous casting is carried out subsequently.

[0048] Case 2

[0049] After being blown in an electric furnace to the final steel composition, the steel output was 141 tons, and the final steel composition was: C content 0.06%, Si content 0.004%, Mn content 0.04%.

[0050] The ladle that holds the molten steel from the electric furnace is in a ladle baking and preheating state before being transported to the steel-tapping position. The ladle is loaded with 13 tons of scrap steel, and the temperature of the scrap steel in the ladle is 900℃.

[0051] During the steel-making process, qualified vanadium slag that meets the requirements is added manually in the chute behind the furnace to the steel flow of the steel-making process. 800 kg of vanadium slag (i.e. 5.19 kg / ton of steel) is added. The composition of the vanadium slag is 10.5% V2O5, 14% SiO2, 13% TiO2, 8% MnO, less than 0.10% P2O5, 35% TFe, and the particle size of the vanadium slag is 10-100mm. At the same time, 14 kg / ton of steel is added with silicon-manganese alloy. After the addition of vanadium slag and silicon-manganese alloy, argon is stirred for 5 minutes, the argon flow rate is 110m³ / hour, and the argon pressure is 1.1MPa. The molten steel ladle is then transported to the LF refining process, and argon is blown from the bottom throughout the LF refining process. After LF enters the station, 0.39kg of ferrosilicon (Si content 70-80%, the rest TFe), 160kg of carbon powder (carbon content>90%), and 900kg of lime are added at the same time. Heat for 5 minutes. At this time, the temperature is 1540℃. Sample analysis of the molten steel shows that the carbon content is 0.14%, the silicon content is 0.15%, and the vanadium content is 0.02%. Continue heating, add 900kg of lime (5-7kg per ton of steel) to make "white slag", add the remaining ferrosilicon and other alloys required by the steel grade, and the temperature of the molten steel is 1595℃ after refining. At this time, the main components of the molten steel are as follows: C content 0.24%, Si content 0.30%, Mn content 1.1%, P content <0.02%, S content <0.03%. After the above process steps are completed, the target vanadium-containing molten steel is obtained, and continuous casting is carried out subsequently.

[0052] Case 3

[0053] After being blown in an electric furnace to the final steel composition, the steel output was 145 tons, and the final steel composition was: C content 0.09%, Si content 0.002%, Mn content 0.04%.

[0054] The ladle that holds the molten steel from the electric furnace is in a ladle baking and preheating state before being transported to the steel-tapping position. The ladle is loaded with 18 tons of scrap steel, and the temperature of the scrap steel in the ladle is 900℃.

[0055] During the steel-making process, qualified vanadium slag that meets the requirements is added manually in the chute behind the furnace to the steel flow of steel-making. 1000 kg of vanadium slag (i.e. 6.13 kg / ton of steel) is added to the vanadium slag. The composition of the vanadium slag is 11.2% V2O5, 13% SiO2, 15% TiO2, 6% MnO, less than 0.10% P2O5, 35% TFe, and the particle size of the vanadium slag is 10-100mm. At the same time, 14 kg / ton of steel of silicon-manganese alloy is added. After the addition of vanadium slag and silicon-manganese alloy, argon is stirred for 5 minutes, the argon flow rate is 110m³ / hour, and the argon pressure is 1.1MPa. The molten steel ladle is then transported to the LF refining process, and argon is blown from the bottom throughout the LF refining process. After LF enters the station, 0.5kg of ferrosilicon (Si content 70-80%, the rest TFe), 140kg of carbon powder (carbon content>90%), and 1100kg of lime are added, and heated for 5 minutes. At this time, the temperature is 1550℃. Sample analysis of the molten steel composition shows that the carbon content is 0.14%, the silicon content is 0.14%, and the vanadium content is 0.024%. Continue heating, add 900kg of lime (5-7kg per ton of steel) to make "white slag", add the remaining ferrosilicon and other alloys required by the steel grade, and the temperature of the molten steel is 1580℃ after refining. At this time, the main components of the molten steel are as follows: C content 0.23%, Si content 0.33%, Mn content 1.05%, P content <0.02%, S content <0.03%. After the above process steps are completed, the target vanadium-containing molten steel is obtained, and continuous casting is carried out subsequently.

[0056] The present invention discloses a low-cost production method for microalloyed construction steel, which has the advantage of significantly reducing costs. The specific comparison is as follows:

[0057] Taking an electric furnace plant with an annual output of 3 million tons as an example, the price of the commonly used 70 vanadium-nitrogen alloy is 140,000 yuan / ton, and the price of vanadium-containing pig iron is 3,800 yuan / ton.

[0058] 1) Calculation of vanadium addition cost for 70% vanadium nitrogen alloy;

[0059] The amount of metallic vanadium required for a ton of steel = 1000 × 0.02% = 0.2 kg;

[0060] The amount of vanadium-nitrogen alloy required per ton of steel = 0.2÷70% = 0.286kg;

[0061] The cost of adding vanadium with 70 vanadium-nitrogen alloy = 0.286÷1000×140000 = 40.04 yuan / ton of steel;

[0062] 2) Calculation of vanadium-enhanced cost of 10% vanadium slag;

[0063] The amount of metallic vanadium required for a ton of steel = 1000 × 0.02% = 0.2 kg;

[0064] The amount of vanadium slag required per ton of steel = 0.2÷0.56÷10% = 3.57kg;

[0065] The cost of adding vanadium with 10% vanadium slag = 3.57÷1000×5100 = 18.2 yuan / ton of steel;

[0066] Ton of steel profit = 40.04-18.2 = 21.84 yuan;

[0067] Based on the above, the use of the results of the present invention is expected to create benefits of more than 20 yuan per ton of steel.

[0068] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-cost production method for microalloyed construction steel, characterized in that: The specific steps include: A1, manganese alloying, silicon partial alloying, and vanadium slag addition during steelmaking in an electric furnace; A2, LF furnace with ferrosilicon alloy added; A3, LF furnace slag making and heating; A4, LF furnace refining to produce white slag; A5, LF refining furnace treatment is completed, vanadium-containing molten steel is obtained, and then continuous casting is carried out. The vanadium slag includes, by weight percentage, 10-13% V2O5, 10-20% SiO2, 10-20% TiO2, 5-10% MnO, less than 0.10% P2O5, 30-40% TFe, and a particle size of 10-100 mm. In step A1, the ladle containing the molten steel from the electric furnace is in a ladle baking preheating state before being transported to the steel tapping position. The ladle is filled with scrap steel, and the scrap steel temperature in the ladle is 900-1100°C; The vanadium slag is transported to the alloy material bin behind the electric furnace. During the steel-making process, 3.5-7 kg / ton of steel of vanadium slag is added manually in the chute behind the furnace to the steel flow. During the steel tapping process in step A1, silicon-manganese alloy is added along with the steel flow, wherein the Si content is 15-25%, the manganese content is 65-75%, and the rest is iron, and the silicon-manganese alloy is 12-13kg / ton of steel; After the silicon-manganese alloy is added, stir with argon for 4-7 minutes, the argon flow rate is 100-150m³ / hour, the argon pressure is 0.8-1.2MPa, and the ladle is then transported to the LF furnace; In step A2, after LF enters the station, 0.35-0.45kg of ferrosilicon is added per ton of steel, wherein the Si content is 70-80%, and the rest is TFe, 0.4-1.5kg of carbon powder per ton of steel, the carbon content is >90%, and 6-8kg of lime per ton of steel is added at the same time. The steel is heated for 5 minutes, at which time the temperature is 1520-1540°C. The carbon content of the molten steel is 0.14-0.16%, the silicon content is 0.13-0.15%, and the vanadium content is 0.012-0.016%; In step A3, continue heating, add lime 5-7 kg / ton steel to make "white slag", add the remaining ferrosilicon alloy required by the steel grade, and the temperature of the molten steel is 1570-1610°C after refining. At this time, the main components of the molten steel are as follows: C content 0.22-0.25%, Si content 0.29-0.34%, Mn content 0.95-1.1%, P content <0.02%, S content <0.03%.

2. A low-cost production method for microalloyed construction steel according to claim 1, characterized in that: The final composition of molten steel in the electric furnace: C content 0.05-0.1%, Si content 0.002-0.006%, Mn content 0.02-0.06%.

3. A low-cost production method for microalloyed construction steel according to claim 1 or 2, characterized in that: In steps A2-A5, argon is blown from the bottom throughout the LF refining process. The bottom blowing system consists of gas and blowing pipelines. The gas is nitrogen or argon. The bottom blowing gas flow rate is 50-150m³ / hour. The blowing pipeline is connected to the air-permeable bricks at the bottom of the electric furnace through a pipe. The number of bottom blowing air-permeable bricks is 1-3.