Method for smelting low-phosphorus and low-sulfur steel grade by using stainless steel dephosphorization station
By performing deep desulfurization and deep dephosphorization treatment at stainless steel dephosphorization stations, the combined technology of spray gun and oxygen gun was used to successfully reduce the sulfur and phosphorus content in the molten iron, solving the problem of the inability to effectively smel low-sulfur and phosphorus steel seeds in the existing technology, and achieving efficient and low-cost steel seeds.
Patent Information
- Application Number
- CN202510406894.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-02
- Publication Date
- 2025-06-10
AI Technical Summary
The existing stainless steel dephosphorization stations cannot effectively smel low-sulfur and phosphorus steel seeds, resulting in difficulty in smelting low-phosphorus sulfur steel seeds.
By performing deep desulfurization and deep dephosphorization treatment at stainless steel dephosphorization stations, passivation of lime powder and oxygen using dephosphorization spray guns and oxygen guns, combined with the addition of fluorite, aluminum particles, ferrosilicon and iron oxide sheets, the sulfur and phosphorus content in the molten iron is gradually reduced.
The sulfur and phosphorus content in the molten iron has been reduced to below 0.0043-0.0048%, ensuring the smelting quality of low-phosphorus sulfur steel, avoiding sulfur rebate, and zero transformation of equipment and low cost.
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of stainless steel smelting, and relates to a method for smelting low-phosphorus and low-sulfur steel grades by using a stainless steel dephosphorization station. Background Art
[0002] The original design of the stainless steel dephosphorization station cannot perform hot metal desulfurization. Combining with the current on-site production process and equipment, the present invention directly conducts deep desulfurization treatment on the hot metal without upgrading and transforming the on-site equipment, so as to ensure the successful smelting of low-phosphorus and low-sulfur steel grades. The present invention aims to use the stainless steel dephosphorization station for deep desulfurization and deep dephosphorization smelting. Summary of the Invention
[0003] The purpose of the present invention is to provide a method for smelting low-phosphorus and low-sulfur steel grades by using a stainless steel dephosphorization station in view of the problems existing in the prior art, which solves the problem that the stainless steel dephosphorization station cannot smelt low-sulfur and low-phosphorus steel grades under the existing equipment and facilities, and ensures the successful production of special steel products.
[0004] To this end, the present invention adopts the following technical solutions: A method for smelting low-phosphorus and low-sulfur steel grades by using a stainless steel dephosphorization station, comprising the following steps: a. Skimming hot metal from the blast furnace: Lift the incoming blast furnace hot metal to the skimming platform. After skimming the slag carried by the blast furnace hot metal, measure the temperature and take samples of the blast furnace hot metal. After the temperature measurement and sampling are completed, hot charge the blast furnace hot metal into the ladle.
[0005] b. Deep desulfurization in the dephosphorization station: Lift the ladle to the dephosphorization station. After the hot metal enters the station, measure the temperature first. Use a dephosphorization lance to blow passivated lime powder into the ladle at a blowing speed of 50 - 100 kg / min and a blowing amount of 15 - 40 kg / t of hot metal. During the process, add 2.5 - 6.5 kg / t of hot metal of fluorite, add 0.5 - 6.5 kg / t of hot metal of small-grained ferrosilicon or 0.5 - 6.5 kg / t of hot metal of aluminum pellets. After the blowing is completed, use a slag skimmer to completely skim the desulfurization slag, then measure the temperature and take samples, and desulfurize the sulfur in the hot metal to less than 0.005%; c. Deep dephosphorization in the dephosphorization station: For the hot metal after desulfurization, simultaneously lower the lance and the oxygen lance in the dephosphorization station for deep dephosphorization. Use the oxygen lance to blow oxygen into the ladle at a speed of 30 - 50 NM3 / min and a total oxygen amount of 900 - 1500 NM3; while blowing oxygen, use the dephosphorization lance to blow passivated lime powder into the ladle at a blowing speed of 30 - 50 kg / min and a blowing amount of 16 - 35 kg / t of hot metal. During the process, add 0.5 - 3.0 kg / t of hot metal of fluorite, add 25 - 65 kg / t of hot metal of iron oxide scale during the process. After the blowing is completed, use a slag skimmer to completely skim the dephosphorization slag, then measure the temperature and take samples, and dephosphorize the phosphorus in the hot metal to less than 0.005%, while ensuring that the sulfur in the hot metal remains below 0.005%; d. AOD Smelting: After the phosphorus and sulfur in the hot metal are removed to less than 0.005% at the dephosphorization station, a covering agent is thrown into the ladle for heat preservation. The ladle is lifted by a crane to the AOD, and the hot metal is poured into the furnace. Temperature measurement and sampling are carried out, and production smelting is carried out according to the composition of the hot metal in the furnace.
[0006] In step b, the injection amount of the passivated lime powder is 15.5 - 26.5 kg / t of hot metal, the addition amount of fluorite is 2 - 4 kg / t of hot metal, and 1.6 kg / t of hot metal of aluminum pellets or 2 kg / t of hot metal of ferrosilicon is selectively added.
[0007] In step c, the addition amount of the mill scale is 50 - 80 kg / t of hot metal, and the total amount of injected oxygen is 1470 - 1930 Nm³.
[0008] In steps b and c, the temperature of the hot metal after slag skimming is controlled at 1275 - 1375 °C.
[0009] Before AOD smelting in step d, the composition of the hot metal satisfies: C 3.36 - 3.52%, Si 0 - 0.018%, Mn 0.046 - 0.157%, P ≤ 0.0049%, S ≤ 0.0048%.
[0010] The beneficial effects of the present invention are as follows: The present invention conducts deep desulfurization and deep dephosphorization smelting using a stainless - steel dephosphorization station. The stainless - steel dephosphorization station was originally designed without the ability to desulfurize hot metal. The present invention combines the current on - site production process and equipment, without upgrading and transforming the on - site equipment, directly conducts deep desulfurization treatment on the hot metal to ensure the smelting of low - phosphorus and low - sulfur steel grades. The equipment of the present invention has zero transformation, low cost, improved desulfurization efficiency, the sulfur content is reduced to 0.0043 - 0.0048%, and phosphorus removal synchronously controls sulfur, avoiding the phenomenon of sulfur return. Specific Embodiments
[0011] The present invention will be described in detail below in combination with specific embodiments.
[0012] Example 1 Deep desulfurization and deep dephosphorization smelting are carried out in a stainless - steel dephosphorization station. The specific steps are as follows: a. Skimming of blast - furnace hot metal: The incoming blast - furnace hot metal is lifted to the skimming platform. After skimming the slag carried by the blast - furnace hot metal, temperature measurement and sampling are carried out on the blast - furnace hot metal. The composition and temperature of the blast - furnace hot metal are: C: 4.73%, Si: 0.937%, Mn: 0.914%, P: 0.077%, S: 0.034%, temperature: 1349 °C. After temperature measurement and sampling, the blast - furnace hot metal is hot - charged into the ladle.
[0013] b. Deep desulfurization at the dephosphorization station: Lift the ladle to the dephosphorization station. After the hot metal enters the station, measure its temperature first. Use a dephosphorization spray gun to blow passivated lime powder into the ladle at a blowing speed of 50 kg / min, with 16 kg of lime powder per ton of hot metal blown. During the process, add 2.5 kg of fluorite per ton of hot metal and 1.6 kg of aluminum pellets per ton of hot metal. After the blowing is completed, use a slag skimmer to completely remove the desulfurized slag, then measure the temperature and take samples. The composition and temperature of the desulfurized hot metal are: C: 4.42%, Si: 0.612%, Mn: 0.786%, P: 0.0787%, S: 0.0047%, temperature: 1296 °C; c. Deep dephosphorization at the dephosphorization station: For the hot metal after desulfurization, lower the spray gun and oxygen lance simultaneously at the dephosphorization station for deep dephosphorization. Use the oxygen lance to blow oxygen into the ladle at a speed of 33 NM3 / min, with 1930 NM3 of oxygen blown; while blowing oxygen, use the dephosphorization spray gun to blow passivated lime powder into the ladle at a blowing speed of 35 kg / min, with 30 kg of lime powder per ton of hot metal blown. During the process, add 0.8 kg of fluorite per ton of hot metal and 53 kg of iron oxide scale per ton of hot metal. After the blowing is completed, use a slag skimmer to completely remove the dephosphorized slag, then measure the temperature and take samples. The composition and temperature of the dephosphorized hot metal are: C: 3.37%, Si: 0%, Mn: 0.108%, P: 0.0043%, S: 0.0047%, temperature: 1375 °C; d. AOD smelting: After the dephosphorization station reduces the phosphorus and sulfur in the hot metal to below 0.005%, throw a covering agent into the ladle for heat preservation. Use a crane to lift the ladle to the AOD. The AOD pours the hot metal into the furnace, measures the temperature and takes samples. The composition and temperature of the hot metal are: C: 3.37%, Si: 0%, Mn: 0.108%, P: 0.0047, S: 0.0047, temperature: 1300 °C, and carry out production smelting according to the composition of the hot metal in the furnace.
[0014] Example 2 Deep desulfurization and deep dephosphorization smelting are carried out at the stainless steel dephosphorization station. The specific steps are as follows: a. Skimming the slag from the blast furnace hot metal: Lift the incoming blast furnace hot metal to the skimming platform. After skimming the slag carried by the blast furnace hot metal, measure the temperature and take samples of the blast furnace hot metal. The composition and temperature of the blast furnace hot metal are: C: 4.49%, Si: 0.617%, Mn: 0.82%, P: 0.078%, S: 0.037%, temperature: 1339 °C. After measuring the temperature and taking samples, hot charge the blast furnace hot metal into the ladle.
[0015] b. Deep desulfurization at the dephosphorization station: Lift the ladle to the dephosphorization station. After the hot metal enters the station, measure its temperature first. Use a dephosphorization spray gun to blow passivated lime powder into the ladle at a blowing speed of 70 kg / min, blowing 18 kg of lime powder per ton of hot metal. During the process, add 2.8 kg of fluorite per ton of hot metal and 2 kg of small-grained ferrosilicon per ton of hot metal. After the blowing is completed, use a slag skimmer to completely remove the desulfurization slag, then measure the temperature and take samples. The composition and temperature of the desulfurized hot metal are: C: 4.49%, Si: 0.658%, Mn: 0.824%, P: 0.08, S: 0.0043, temperature: 1275°C; c. Deep dephosphorization at the dephosphorization station: For the hot metal after desulfurization, simultaneously lower the spray gun and oxygen lance at the dephosphorization station for deep dephosphorization. Use the oxygen lance to blow oxygen into the ladle at a speed of 31 NM3 / min, blowing 1500 NM3 of oxygen; while blowing oxygen, use the dephosphorization spray gun to blow passivated lime powder into the ladle at a blowing speed of 33 kg / min, blowing 22.3 kg of lime powder per ton of hot metal. During the process, add 1.3 kg of fluorite per ton of hot metal and 60 kg of iron oxide scale per ton of hot metal. After the blowing is completed, use a slag skimmer to completely remove the dephosphorization slag, then measure the temperature and take samples. The composition and temperature of the dephosphorized hot metal are: C: 3.36%, Si: 0.001%, Mn: 0.157%, P: 0.0046, S: 0.0045, temperature: 1358°C; d. AOD smelting: After the dephosphorization station reduces the phosphorus and sulfur in the hot metal to below 0.005%, throw a covering agent into the ladle for heat preservation. Use a crane to lift the ladle to the AOD. The AOD pours the hot metal into the furnace, measures the temperature and takes samples. The composition and temperature of the hot metal are: C: 3.36%, Si: 0.001%, Mn: 0.157%, P: 0.0048, S: 0.0046, temperature: 1313°C, and carry out production smelting according to the composition of the hot metal in the furnace.
[0016] Example 3 Deep desulfurization and deep dephosphorization smelting are carried out at the stainless steel dephosphorization station. The specific steps are as follows: a. Skimming the slag from the blast furnace hot metal: Lift the incoming blast furnace hot metal to the slag skimming platform. After skimming the slag carried by the blast furnace hot metal, measure the temperature and take samples of the blast furnace hot metal. The composition and temperature of the blast furnace hot metal are: C: 4.57%, Si: 0.758%, Mn: 0.689%, P: 0.0816%, S: 0.035%, temperature: 1370°C. After measuring the temperature and taking samples, hot charge the blast furnace hot metal into the ladle.
[0017] b. Deep desulfurization at the dephosphorization station: Lift the ladle to the dephosphorization station. After the hot metal enters the station, measure the temperature first. Use a dephosphorization spray gun to blow passivated lime powder into the ladle at a blowing speed of 100 kg / min, and blow 26.7 kg / t of hot metal lime powder. Add 4 kg / t of hot metal fluorite during the process. After the blowing ends, use a slag skimmer to completely remove the desulfurized slag, and then measure the temperature and take samples. The composition and temperature of the desulfurized hot metal are: C: 4.45%, Si: 0.571%, Mn: 0.782%, P: 0.0964%, S: 0.0048%, and the temperature: 1305°C; c. Deep dephosphorization at the dephosphorization station: For the hot metal after desulfurization, lower the spray gun and oxygen lance simultaneously at the dephosphorization station for deep dephosphorization. Use the oxygen lance to blow oxygen into the hot metal ladle at a speed of 33 NM3 / min, and blow 1470 NM3 of oxygen. While blowing oxygen, use the dephosphorization spray gun to blow passivated lime powder into the ladle at a blowing speed of 35 kg / min, and blow 23.4 kg / t of hot metal lime powder. Add 0.8 kg / t of hot metal fluorite during the process, and add 65 kg / t of hot metal iron oxide scale during the process. After the blowing ends, use a slag skimmer to completely remove the dephosphorized slag, and then measure the temperature and take samples. The composition and temperature of the dephosphorized hot metal are: C: 3.52%, Si: 0.018%, Mn: 0.046%, P: 0.0049%, S: 0.0048%, and the temperature: 1305°C; d. AOD smelting: After the dephosphorization station reduces the phosphorus and sulfur in the hot metal to below 0.005%, throw a covering agent into the ladle for heat preservation. Use a crane to lift the ladle to the AOD. The AOD pours the hot metal into the furnace, measures the temperature and takes samples. The composition and temperature of the hot metal are: C: 3.52%, Si: 0.018%, Mn: 0.046%, P: 0.0049%, S: 0.0045%, and the temperature: 1294°C. Conduct production smelting according to the composition of the hot metal in the furnace.
[0018] Using the method of this invention, the problem that the hot metal desulfurization cannot be carried out at the stainless steel dephosphorization station according to the original design is solved. This invention combines the current on-site production process and equipment, without upgrading and transforming the on-site equipment, directly conducts deep desulfurization treatment on the hot metal to ensure the smelting of low-phosphorus and low-sulfur steel grades.
Claims
1. A method for smelting low-phosphorus and low-sulfur steel grades using a stainless steel dephosphorization station, characterized in that: The following steps are involved: a. Deslagging of molten iron from blast furnace: Lift the molten iron from blast furnace to the deslagging platform, remove the slag, measure the temperature and take samples, and then hot load it into the ladle; b. Deep desulfurization at dephosphorization station: hoist the ladle to the dephosphorization station, measure the temperature after the molten iron enters the station, use the dephosphorization spray gun to spray passivation lime powder into the ladle, the spraying speed is 50-100kg / min, the spraying amount is 15-40kg / t molten iron, add fluorite 2.5-6.5kg / t molten iron, add small ferrosilicon 0.5-6.5kg / t molten iron or aluminum granules 0.5-6.5kg / t molten iron, after the spraying is completed, use the slag scraper to completely remove the desulfurization slag, and then measure the temperature and take samples to remove the sulfur in the molten iron to below 0.005%; c. Deep dephosphorization at dephosphorization station: After desulfurization, the molten iron is subjected to deep dephosphorization by spray gun and oxygen gun at the same time in the dephosphorization station. Oxygen is blown into the ladle with oxygen gun at a speed of 30-50NM3 / min and a total oxygen volume of 900-1500NM3; the dephosphorization spray gun sprays passivation lime powder into the ladle at a speed of 30-50kg / min and a spray volume of 16-35kg / t molten iron. During the process, fluorite of 0.5-3.0kg / t molten iron is added, and iron oxide scale of 25-65kg / t molten iron is added. After the spraying is completed, the dephosphorization slag is completely removed by a slag scraper, and then temperature measurement and sampling are performed to remove the phosphorus in the molten iron to below 0.005%, and at the same time ensure that the sulfur in the molten iron is kept below 0.005%; d. AOD smelting: After the dephosphorization station removes phosphorus and sulfur in the molten iron to below 0.005%, a covering agent is thrown into the iron ladle for insulation. The iron ladle is hoisted to the AOD by a crane. The AOD adds molten iron into the furnace, measures temperature and takes samples, and performs production smelting according to the composition of the molten iron in the furnace.
2. The method according to claim 1, characterized in that: In step b, the injection amount of the passivation lime powder is 15.5-26.5 kg / t molten iron, the addition amount of fluorite is 2-4 kg / t molten iron, and 1.6 kg / t molten iron of aluminum particles or 2 kg / t molten iron of ferrosilicon are selectively added.
3. The method according to claim 1, characterized in that: In step c, the amount of iron oxide added is 50-80 kg / t molten iron, and the total amount of oxygen injected is 1470-1930 Nm³.
4. The method according to claim 1, characterized in that: In steps b and c, the temperature of the molten iron after slagging is controlled at 1275-1375°C.
5. The method according to claim 1, characterized in that: In step d, the composition of molten iron before AOD smelting satisfies: C 3.36-3.52%, Si 0-0.018%, Mn 0.046-0.157%, P≤0.0049%, S≤0.0048%.