Converter smelting method of low-iron-consumption low-temperature low-silicon molten iron

Abstract

The invention relates to the technical field of converter smelting, in particular to a converter smelting method of low-iron-consumption low-temperature low-silicon molten iron, which comprises the following steps: (1) establishing a heat compensation model in the smelting process; (2) starting blowing and sparking for smelting, controlling the early-stage lance position to be at a first lance position value, controlling the oxygen blowing flow to be a first oxygen blowing flow value, increasing the oxygen blowing flow to a second oxygen blowing flow value when the to-be-blown oxygen amount is the first oxygen blowing value, and adding slag; (3) after the slag charge is added, increasing the oxygen blowing flow to a third oxygen blowing flow value, lowering the lance position to a third lance position value in the blowing process, and supplementing active lime into the furnace in batches; and (4) when the oxygen blowing amount meets the second oxygen blowing value, measuring the sublance, lowering the carbon pulling lance position to a fourth lance position value in the later period, meanwhile, increasing the oxygen blowing flow to a fourth oxygen blowing flow value, and when the oxygen blowing amount meets the third oxygen blowing value, lifting the lance, and ending blowing. According to the method, accurate temperature increasing and heat supplementing can be achieved, slagging is further promoted, dry returning in the blowing process is prevented, and the slagging and dephosphorization effects are guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of converter smelting, and in particular to a converter smelting method of low-iron-loss, low-temperature and low-silicon molten iron. Background Art

[0002] Low iron loss, low temperature and low silicon molten iron is a state of molten iron with specific requirements in the metallurgical industry. Its characteristics are mainly reflected in three aspects: low iron loss, low temperature and low silicon content.

[0003] In the converter smelting process, heat mainly comes from the physical heat and chemical heat of molten iron. Low iron consumption usually refers to the minimum amount of molten iron required to smelt a furnace of steel in the steelmaking process by optimizing process parameters, reducing raw materials and supplementary heat operations. Low temperature means that the temperature of molten iron is relatively low when it is discharged from the furnace or enters the converter. The physical heat of low-temperature molten iron is relatively low, which is not conducive to converter slag and affects dephosphorization. Low-silicon molten iron means that the silicon content in molten iron is low, which means that the chemical heat contained in the molten iron is low, which is not conducive to raising the temperature and the dephosphorization reaction. Low-iron consumption, low-temperature, low-silicon molten iron is prone to problems such as slag, sticky scrap steel and overoxidation in the actual smelting process, which can easily bring quality and safety risks.

[0004] Smelting low-iron-loss, low-temperature, low-silicon molten iron can effectively increase the scrap steel ratio, increase output, reduce costs and increase efficiency. It has broad application prospects. There is increasing attention in China on low-iron-loss, low-temperature, low-silicon molten iron.

[0005] For example, patent CN 115261550A discloses a converter smelting method of low-silicon molten iron, which uses high-silicon pig iron instead of scrap steel. Its disadvantage is that the composition of high-silicon iron blocks is unstable, the silicon-enhancing effect is unstable, and it is easy to cause splashing during the blowing process and affect the dephosphorization effect.

[0006] For example, CN 115537491A discloses a converter blowing method for low-temperature, low-silicon molten iron, a production method in which an alloy containing silicon, manganese and aluminum is added to the converter when the molten iron is added, and the temperature is raised by adding silicon carbide, silicon-manganese alloy and aluminum particles. However, the method has the following disadvantages: it is only applicable to converter production with a smaller volume, has a high content of silicon, manganese and aluminum, and has a large amount of slag left, which easily leads to active slag in the process and splashing. Summary of the invention

[0007] In view of the technical problems of poor dephosphorization effect and large slag flow in existing smelting, the present invention provides a converter smelting method of low iron consumption, low temperature and low silicon molten iron, which can achieve precise temperature increase and heat supplement, further promote slag removal, prevent drying out during the blowing process, and ensure slag removal and dephosphorization effects.

[0008] The present invention provides a converter smelting method of low-iron-loss, low-temperature and low-silicon molten iron, comprising the following steps: (1) Establishing a heat supplement model during the smelting process, which includes calculating the amount of ferrosilicon added and the amount of heating agent added; (2) Scrap steel and molten iron are loaded into the converter, and ignition and smelting are started. The initial gun position is controlled to be at the first gun position value, and the oxygen blowing flow rate is controlled to be the first oxygen blowing flow rate value. When the oxygen blowing amount meets the first oxygen blowing value, the oxygen blowing flow rate is increased to the second oxygen blowing flow rate value, and the gun position is lowered to the second gun position value. Slag material is added. The slag material includes active lime, magnesium balls, ferrosilicon and heating agent, etc.; (3) After the slag material is added, the oxygen blowing flow rate is increased to the third oxygen blowing flow rate value, the gun position during the blowing process is lowered to the third gun position value, and active lime is added to the furnace in batches at the same time; (4) When the oxygen blowing amount meets the second oxygen blowing value, measure the auxiliary gun. Later, the carbon pulling gun position drops to the fourth gun position value. At the same time, the oxygen blowing flow rate is increased to the fourth oxygen blowing flow rate value. When the oxygen blowing amount meets the third oxygen blowing value, lift the gun and the refining is completed.

[0009] Furthermore, the converter type is a 210t converter, and the converter smelting iron consumption is 780kg / t. The 210t converter has a large loading capacity, achieving a large output while reducing iron consumption.

[0010] Furthermore, in step (1), the calculation formula for the amount of ferrosilicon added is, M1=(0.4%-Si%)×1000×total charge amount÷74%; M1 is the amount of ferrosilicon added, in kg; Si% is the percentage of Si% in the designed chemical composition of molten iron; and the total charge amount is the total charge amount of scrap steel and molten iron, in kg.

[0011] Furthermore, in step (1), the calculation formula for the amount of the heating agent added is, M2=(1420-T)÷20×1000; M2 is the amount of the heating agent added, in kg; T is the molten iron temperature.

[0012] Furthermore, in step (2), the first gun position value is 2.5~2.6m, and the first oxygen blowing flow rate value is 26000~30000m 3 / h, the first oxygen blowing value is 430Nm 3 The second gun position is 2.4m, and the second oxygen blowing flow rate is 33000m 3 / h.

[0013] Furthermore, in step (2), the amount of active lime added is controlled so that the slag basicity is 3.0.

[0014] Furthermore, in step (3), the third oxygen blowing flow rate is 45000~48000m 3 / h, the second gun position value is 2.1~2.4m.

[0015] Furthermore, in step (3), the dosage of each batch of active lime is ≤500 kg, and the dosage ratio of the active lime in step (2) to the total dosage of all active limes in step (3) is 7:3.

[0016] Furthermore, in step (4), the second oxygen blowing value is 9500-10800 Nm 3 , the fourth gun position value is 1.9m, the fourth oxygen blowing flow value is 51000m 3 / h, the third oxygen blowing value is 13100~13600Nm 3 .

[0017] The beneficial effects of the present invention are: (1) The present invention establishes a heat supplement model during the smelting process, accurately calculates the amount of ferrosilicon and heating agent added, accurately supplements heat, increases the molten pool temperature, promotes the melting of the early slag-making material, reduces the risk of scrap steel sticking, and achieves the purpose of safe and stable production increase.

[0018] (2) The present invention uses the method of changing the gun position and changing the pressure to adjust the gun position and oxygen blowing flow rate at each stage, and makes flexible adjustments; the early gun position and oxygen blowing can take advantage of the bottom blowing to promote early slagging, reduce blowing loss, and increase the temperature to the maximum extent; active lime is added in batches during the blowing process to ensure the melting and blowing temperature increase effect; finally, the later carbon pulling gun position and oxygen blowing flow rate are adjusted to further increase the molten pool temperature, press the gun in place, reduce overoxidation, and reduce the total iron in the slag. It has the advantages of promoting slagging and preventing drying during the blowing process, and ensures the slagging and dephosphorization effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a curve diagram of the gun position and material addition changes during smelting in Example 1 of the specific implementation method of the present invention.

[0021] Figure 2 This is a curve diagram of the gun position and the feeding changes during smelting in Example 2 of the specific implementation method of the present invention. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0023] In the following example, the amount of ferrosilicon added M1 is calculated by the following formula: M1=(0.4%-Si%)×1000×total charge ÷ 74%, M1 is in kg; Si% is the percentage of Si in the chemical composition design of molten iron; the total charge is the total charge of scrap steel and molten iron, in kg.

[0024] In the following example, the calculation formula of the amount of heating agent added M2 is: M2=(1420-T)÷20×1000; M2 is the amount of heating agent added, in kg; T is the temperature of molten iron. The heating agent is a carbonaceous heating agent with a fixed carbon content of 80.12%.

[0025] Example 1 This embodiment produces low carbon steel, steel grade SPHC, converter type is 210t converter, converter smelting iron consumption is 780kg / t, molten iron chemical composition and percentage content are: C: 4.42%, Si: 0.10%, Mn: 0.2%, P: 0.108%, S: 0.005%, the balance is Fe and unavoidable impurities. The molten iron temperature is 1356°C. According to the formula, 998kg ferrosilicon and 3222kg warming agent should be added.

[0026] Combination Figure 1 , a converter smelting method of low iron loss, low temperature and low silicon molten iron, comprising the following steps: Scrap steel and molten iron are loaded into the converter. After normal blowing and ignition, the gun position is stabilized at the previous gun position of 2.6m, and the flow rate is 26000m 3 / h, wait for the flame to stabilize, oxygen blowing rate 430Nm 3 Gradually increase the flow rate to 33000m 3 / h, the gun position is lowered to 2.4m, and the first batch of slag is added. The first batch of slag includes 4667kg of active lime, 800kg of magnesium oxide (lightly burned magnesium balls), 998kg of ferrosilicon and 3222kg of heating agent. The amount of active lime added is based on the slag basicity being controlled at 3.0.

[0027] After the first batch of slag was added, the flow rate was gradually increased to 48000m 3 / h; the process gun position is lowered to 2.3m, and according to the active conditions of blowing flame and slag melting, the oxygen blowing rate is 4200 (representing 4200Nm3 , the same below), 5500 oxygen, 7000 oxygen and 7500 oxygen, add about 500kg of active lime to ensure the melting and blowing temperature raising effect. Blow to 8500 oxygen, add 500kg of sintered ore to balance the temperature.

[0028] Blowing to 10800m 3 The auxiliary gun is measured after oxygen, and the carbon pulling gun is at 1.9m in the later stage, with a flow rate of 51000m 3 / h, to 13100 oxygen lifting gun, the end point oxygen was measured at 420ppm, the temperature was 1633℃, the chemical analysis showed carbon was 0.053%, and phosphorus was 0.015%.

[0029] Example 2 This embodiment produces low carbon steel, steel grade Q355B, converter type is 210t converter, converter smelting iron consumption is 780kg / t, molten iron chemical composition and percentage content are: C: 4.53%, Si: 0.12%, Mn: 0.18%, P: 0.115%, S: 0.016%, the balance is Fe and unavoidable impurities. The molten iron temperature is 1348°C. According to the formula, 889kg ferrosilicon and 3600kg warming agent should be added.

[0030] Combination Figure 2 , a converter smelting method of low iron loss, low temperature and low silicon molten iron, comprising the following steps: Scrap steel and molten iron are loaded into the converter. After normal blowing and ignition, the gun position is stabilized at the previous gun position of 2.6m, and the flow rate is 30000m 3 / h, wait for the flame to stabilize, oxygen blowing rate 430Nm 3 Gradually increase the flow rate to 33000m 3 / h, the gun position is lowered to 2.4m, and the first batch of slag is added. The first batch of slag includes 4667kg of active lime, 800kg of magnesium oxide, 89kg of ferrosilicon and 3600kg of heating agent. The amount of active lime added is controlled according to the slag basicity at 3.0.

[0031] After the first batch of slag was added, the flow rate was gradually increased to 45000m 3 / h; the process gun position is lowered to 2.3m, and according to the active conditions of blowing flame and slag melting, about 500kg of active lime is added at 4200 oxygen, 5500 oxygen, 7000 oxygen and 7500 oxygen to ensure the melting and blowing temperature raising effect. When blowing reaches 8500 oxygen, 500kg of sintered ore is added to balance the temperature.

[0032] Blowing to 9500m 3 The auxiliary gun for oxygen post-measurement, the carbon pulling gun position at the later stage is 1.9m, and the flow rate is 51000m 3 / h, to 13600 oxygen lifting gun, the end point oxygen was measured at 413ppm, the temperature was 1641℃, the carbon was 0.052%, and the phosphorus was 0.013%.

[0033] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A converter smelting method for low iron loss, low temperature and low silicon molten iron, characterized in that: The steps include: (1) Establishing a heat supplement model during the smelting process, which includes calculating the amount of ferrosilicon added and the amount of heating agent added; (2) Scrap steel and molten iron are loaded into the converter, and ignition and smelting are started. The initial gun position is controlled to be at the first gun position value, and the oxygen blowing flow rate is controlled to be the first oxygen blowing flow rate value. When the oxygen blowing amount meets the first oxygen blowing value, the oxygen blowing flow rate is increased to the second oxygen blowing flow rate value, and the gun position is lowered to the second gun position value. Slag material is added. The slag material includes active lime, magnesium balls, ferrosilicon and heating agent, etc.; (3) After the slag material is added, the oxygen blowing flow rate is increased to the third oxygen blowing flow rate value, the gun position during the blowing process is lowered to the third gun position value, and active lime is added to the furnace in batches at the same time; (4) When the oxygen blowing amount meets the second oxygen blowing value, measure the auxiliary gun. Later, the carbon pulling gun position drops to the fourth gun position value. At the same time, the oxygen blowing flow rate is increased to the fourth oxygen blowing flow rate value. When the oxygen blowing amount meets the third oxygen blowing value, lift the gun and the refining is completed.

2. The converter smelting method of low iron loss, low temperature and low silicon molten iron according to claim 1, characterized in that: The converter type is a 210t converter, and the converter smelting iron consumption is 780kg / t.

3. The converter smelting method of low iron loss, low temperature and low silicon molten iron according to claim 1, characterized in that: In step (1), the calculation formula for the amount of ferrosilicon added is, M1=(0.4%-Si%)×1000×total charge amount÷74%; M1 is the amount of ferrosilicon added, in kg; Si% is the percentage of Si in the designed chemical composition of molten iron; and the total charge amount is the total charge amount of scrap steel and molten iron, in kg.

4. The converter smelting method of low iron loss, low temperature and low silicon molten iron according to claim 1, characterized in that: In step (1), the calculation formula for the amount of heating agent added is, M2=(1420-T)÷20×1000; M2 is the amount of heating agent added, in kg; T is the molten iron temperature.

5. The converter smelting method of low iron loss, low temperature and low silicon molten iron according to claim 1, characterized in that: In step (2), the first gun position value is 2.5~2.6m, and the first oxygen blowing flow rate value is 26000~30000m 3 / h, the first oxygen blowing value is 430Nm 3 The second gun position is 2.4m, and the second oxygen blowing flow rate is 33000m 3 / h.

6. The converter smelting method of low iron loss, low temperature and low silicon molten iron according to claim 1, characterized in that: In step (2), the amount of active lime added is controlled according to the slag basicity at 3.

0.

7. The converter smelting method of low iron loss, low temperature and low silicon molten iron according to claim 1, characterized in that: In step (3), the third oxygen blowing flow rate is 45000-48000m 3 / h, the third gun position value is 2.1~2.4m.

8. The converter smelting method of low iron loss, low temperature and low silicon molten iron according to claim 1, characterized in that: In step (3), the dosage of each batch of active lime is ≤500 kg, and the dosage ratio of the active lime in step (2) to the total dosage of all active limes in step (3) is 7:

3.

9. The converter smelting method of low iron loss, low temperature and low silicon molten iron according to claim 1, characterized in that: In step (4), the second oxygen blowing value is 9500-10800Nm 3 , the fourth gun position value is 1.9m, the fourth oxygen blowing flow value is 51000m 3 / h, the third oxygen blowing value is 13100~13600Nm 3 .

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