A method for smelting in a converter with full molten iron under dry dust removal conditions

Abstract

The application discloses a method for converter smelting with full molten iron under dry dedusting conditions, comprising the following steps: step 1, slag control, after tapping is finished, a slag splashing for protecting the converter is performed, after the slag splashing is finished, the slag is poured out, and according to a specific slag pouring angle, a certain amount of slag is reserved; step 2, auxiliary material control, according to the composition of the molten iron, the auxiliary material required to be added is calculated, then 60% of the total amount of raw material required to be added is weighed and added into the converter after the slag pouring is finished; step 3, bottom blowing control, the converter bottom blowing adopts a mode of 'high, high, low', the oxygen blowing progress is 10%-30%, the bottom blowing flow is 350-400 m 3 / h, the oxygen blowing progress is 40%-70%, the bottom blowing flow is 350-400 m 3 / h, the oxygen blowing progress is 80%-100%, and the bottom blowing flow is 280-300 m 3 / h; and step 4, iron control, after the iron is poured in, the converter is shaken twice, and then the next smelting is performed.

Description

Technical Field

[0001] This invention relates to the field of steel production technology, and in particular to a method for smelting molten iron in a converter under dry dust removal conditions. Background Technology

[0002] In converter steelmaking, the metal charge mainly consists of molten iron and scrap steel. Besides being a metal charge, scrap steel also plays a role in balancing the heat of the molten pool. However, in cases of malfunction in the scrap steel charging equipment (crane), scrap steel cannot be charged, forcing the converter to use only molten iron for smelting. When using only molten iron for smelting, the lack of scrap steel to absorb heat in the early stages leads to high and rapid temperatures in the molten pool, causing a series of problems for stable control of the converter smelting process. The main problems include: high initial temperatures easily cause poor slag formation, resulting in metal splashing; and high molten pool temperatures exacerbate the carbon-oxygen reaction, easily causing explosive splashing and environmental pollution. High initial temperatures also lead to high phosphorus levels at the final stage, resulting in quality problems requiring reprocessing. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for smelting molten iron in a converter under dry dust removal conditions, which can effectively avoid splashing during the smelting process and avoid various drawbacks such as environmental pollution and metal loss caused by splashing; improve the dephosphorization effect in the converter smelting process, avoid the quality problems caused by high phosphorus content at the end due to high initial temperature and subsequent reprocessing, and achieve a stable converter smelting process.

[0004] The technical solution of this invention to solve the above technical problems is: a method for smelting molten iron in a converter under dry dust removal conditions, characterized by comprising the following steps: Step 1: Slag retention control. After tapping, slag splashing is carried out to protect the furnace. After the slag splashing is completed, the slag is dumped. At the same time, a certain amount of slag is retained according to the specific slag tapping angle. Step 2, auxiliary material control: Calculate the auxiliary materials to be added based on the composition of the molten iron, and then weigh 60% of the total amount of raw materials to be added, and add them into the furnace after the slag is poured out. Step 3, Bottom Blowing Control: The converter bottom blowing adopts a "high, high, low" mode, with oxygen blowing progress between 10% and 30%, and a bottom blowing flow rate of 350-400 m³ / h. 3 / h, oxygen blowing progress is 40%-70%, bottom blowing flow rate is 350-400m³ / h. 3 / h, oxygen blowing progress is 80%-100%, bottom blowing flow rate is 280-300m³ / h. 3 / h; Step 4: Iron addition control. After iron addition is completed, shake the furnace back and forth twice before smelting with the lance.

[0005] The present invention further specifies the following: Preferably, in step 1, the calculation is based on the slag discharge angle, specifically 500 kg of slag is discharged for every degree of descent, and 3-4 tons of slag are left.

[0006] Preferably, the auxiliary materials added in step 2 include lime, lightly calcined magnesia balls, raw dolomite, and ore pellets, and the raw materials added include raw dolomite and ore pellets.

[0007] Preferably, in step 2, the lime and lightly calcined magnesia balls are added after the oxygen blowing ignition point in the converter.

[0008] Preferably, the smelting process in step 5 specifically includes the following steps: S1. Slag-forming material addition control: Under dry dust removal conditions, the converter smelting is in semi-oxygen mode for the first 60 seconds, and it is forbidden to add any slag-forming material. After smelting for 60 seconds, the remaining auxiliary materials are added in "small amounts and multiple batches". Among the auxiliary materials, lime, light calcined magnesia balls and raw dolomite must be added completely 5 minutes before smelting, while pellets are added according to the temperature of the smelting process. S2. Gun Position Control: In the early stage of smelting, the gun position is 1600mm; in the middle stage, the gun position is appropriately increased to 1700mm-1900mm; in the later stage of smelting, the gun position is gradually reduced to 1400mm. S3. Oxygen flow rate setting: Oxygen flow rate setting during smelting process is 37000~39000 Nm. 3 / h; Flow rate set to 40000 Nm when measuring TSC secondary gun. 3 / h; S4. Process control: When the secondary gun is first deployed, the target temperature is controlled at 1580℃±30℃ and the carbon content is below 0.35%. S5. Endpoint control: Refer to the secondary dynamic calculation value and combine it with the ladle temperature to ensure that the smelting endpoint temperature is ≥1620℃.

[0009] The beneficial effects of this invention are: this invention can effectively avoid splashing during the smelting of molten iron in a converter, thus avoiding various drawbacks such as environmental pollution and metal loss caused by splashing; it improves the dephosphorization effect in the converter smelting process, avoiding various drawbacks caused by high phosphorus levels at the end point due to high initial temperature, and achieving a stable converter smelting process. Detailed Implementation Example

[0010] This embodiment provides a method for smelting all molten iron in a converter under dry dust removal conditions, and the specific steps are as follows: Step 1: After tapping the steel, perform slag splashing to protect the furnace. After the slag splashing is completed, pour the slag. Tap the slag when the furnace temperature reaches 135 degrees Celsius and pour the slag to 165 degrees Celsius. The amount of slag left in the furnace is 2-4 tons. Step 2: The amount of molten iron added is 160 tons. The auxiliary materials to be added are calculated based on the composition of the molten iron. The composition of the molten iron is shown in Table 1, and the auxiliary materials to be added are shown in Table 2. The lime and lightly calcined magnesia balls in the auxiliary materials are added after the oxygen blowing ignition in the converter. Table 1. Composition and temperature of molten iron Table 2 Added excipients Step 3: Weigh 60% of the total amount of raw material to be added, and add it to the furnace after the slag is removed. The amount of raw material added is shown in Table 3. Table 3 Raw material addition amount Step 4, Bottom Blowing Control: To prevent the large amount of raw material added before ferroalloying from agglomerating after ferroalloying and affecting smelting, the converter bottom blowing adopts a "high, high, low" mode. The bottom blowing function is used to ensure uniform distribution of raw material. The bottom blowing flow rate used is shown in Table 4. Step 5: After the iron is added, shake the furnace twice before and after the iron is poured, then proceed with the smelting process using the lance. This includes the following steps: S1. When smelting reaches 90 seconds, add 2000 kg of lime, 654 kg of lightly calcined magnesia balls, and 894 kg of raw dolomite. The remaining lime, lightly calcined magnesia balls, and raw dolomite in the auxiliary materials must be added completely 5 minutes before smelting. The pellets are added according to the temperature of the smelting process. S2. Lance Position Control: In the early stage of smelting, the lance position is 1600mm to ensure that all the raw materials added in the early stage are melted, and at the same time, to accelerate the addition of silicon and manganese elements in the molten iron oxide and raise the furnace temperature more quickly; in the middle stage, the lance position is appropriately raised to 1700mm-1900mm, and the lance is raised appropriately according to the reaction in the furnace. The movement should not be too large to avoid explosive splashing; in the later stage of smelting, the lance position is gradually lowered to 1400mm to ensure the uniformity of the final composition. S3. Oxygen flow rate setting: Oxygen flow rate setting during smelting process is 37000~39000 Nm. 3 / h, to avoid excessive oxygen flow leading to poor slag formation during the process; the flow rate is set to 40000 Nm when measuring the TSC auxiliary lance. 3 / h, S4. In this embodiment, the TSC process temperature is 1575℃ and the carbon content is below 0.35%; S5, the final temperature is 1634℃, the smelting process is stable, and the steel composition is shown in Table 4. The steel can be tapped after meeting the target requirements. Table 4 Steel Composition By implementing this invention, splashing during the molten iron smelting process in the converter can be effectively avoided, thus preventing various drawbacks such as environmental pollution and metal loss caused by splashing. It also improves the dephosphorization effect in the converter smelting process, avoids quality problems caused by high phosphorus levels at the end point due to high initial temperature, and achieves a stable converter smelting process.

[0011] In addition to the embodiments described above, the present invention may have other implementations. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A method for smelting all molten iron in a converter under dry dust removal conditions, characterized in that: Includes the following steps: Step 1: Slag retention control. After tapping, slag splashing is carried out to protect the furnace. After the slag splashing is completed, the slag is dumped. At the same time, a certain amount of slag is retained according to the specific slag tapping angle. Step 2, auxiliary material control: Calculate the required auxiliary materials based on the composition of the molten iron, and then weigh 60% of the total amount of raw materials to be added. After the slag is removed, add the auxiliary materials to the furnace. The auxiliary materials include lime, lightly calcined magnesia balls, raw dolomite, and ore pellets. The raw materials added include raw dolomite and ore pellets. The lime and lightly calcined magnesia balls are added after the oxygen blowing ignition in the converter. Step 3, Bottom Blowing Control: The converter bottom blowing adopts a "high, high, low" mode, with oxygen blowing progress between 10% and 30%, and a bottom blowing flow rate of 350-400 m³ / h. 3 / h, oxygen blowing progress is 40%-70%, bottom blowing flow rate is 350-400m³ / h. 3 / h, oxygen blowing progress is 80%-100%, bottom blowing flow rate is 280-300m³ / h. 3 / h; Step 4: Iron addition control. After iron addition, the furnace is shaken twice before smelting with the lance. This lance smelting specifically includes the following steps: S1. Slag-forming material addition control: Under dry dust removal conditions, the converter smelting is in semi-oxygen mode for the first 60 seconds, and it is forbidden to add any slag-forming material. After smelting for 60 seconds, the remaining auxiliary materials are added in "small amounts and multiple batches". Among the auxiliary materials, lime, light calcined magnesia balls and raw dolomite must be added completely 5 minutes before smelting. S2. Gun Position Control: In the early stage of smelting, the gun position is 1600mm; in the middle stage, the gun position is appropriately increased to 1700mm-1900mm; in the later stage of smelting, the gun position is gradually reduced to 1400mm. S3. Oxygen flow rate setting: Oxygen flow rate setting during smelting process is 37000~39000 Nm. 3 / h; Flow rate set to 40000 Nm when measuring TSC secondary gun. 3 / h; S4. Process control: When the secondary gun is first deployed, the target temperature is controlled at 1580℃±30℃ and the carbon content is below 0.35%. S5. Endpoint control: Refer to the secondary dynamic calculation value and combine it with the ladle temperature to ensure that the smelting endpoint temperature is ≥1620℃.

2. The method for smelting all molten iron in a converter under dry dust removal conditions according to claim 1, characterized in that: In step 1, the calculation is based on the slag discharge angle, specifically 500 kg of slag is discharged for every degree of descent, and 3-4 tons of slag are left.