Method for recycling thermal casting residues of low-carbon aluminum killed steel in argon blowing station

Abstract

The invention discloses a method for recycling hot casting residues of low-carbon aluminum killed steel in an argon blowing station, which comprises the following steps of: after converter tapping, feeding a steel ladle into a treatment position of the argon blowing station to feed an aluminum wire, then keeping bottom blowing large-flow argon stirring, scattering aluminum particles on the slag surface in batches after wire feeding is finished, and adding limestone on the slag surface in batches after 1 minute; pouring the hot casting residues into a steel ladle, and carrying out bottom argon blowing to keep a middle stirring bright surface; a carburant is evenly scattered on the slag surface in batches, and bottom blowing large-flow argon stirring is kept; after bottom blowing argon stirring is conducted for 3 minutes, lime is added, bottom blowing medium-flow argon stirring is kept, and emulsified residues are formed; after the emulsified slag is formed for 2 minutes, aluminum particles are sprayed on the slag surface, and bottom blowing micro-flow argon soft blowing is kept for at least 5 minutes to form white slag; the steel ladle leaves the station and is poured on a continuous casting table; according to the method, the low-carbon aluminum killed steel does not need to be subjected to LF furnace refining treatment while recycling of the hot casting residues is achieved, and the purpose of reducing the production cost is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallurgy, and particularly relates to a method for recycling hot cast residue slag of low-carbon aluminum-killed steel in an argon blowing station. Background Art

[0002] Cast residue slag is an inevitable product generated in the production of iron and steel smelting. Therefore, the treatment and recycling of cast residue slag are common problems that all iron and steel enterprises must face. At present, most enterprises mainly collect the cast residue slag with a slag ladle, and then transport it to the slag treatment workshop for subsequent "solid waste" treatment. The treatment processes are mainly hot casting method and grid method, but there are problems such as high energy consumption, serious pollution, low metal recovery rate, high labor intensity, time-consuming and laborious, etc.

[0003] After the molten steel pouring is completed, the temperature of the cast residue slag in the ladle is still as high as 1400 - 1600 °C, which is mainly a high-alkalinity reducing slag treated by LF furnace. Due to its high content of CaO and Al2O3 and low content of (TFe + MnO), it has strong pre-melting property and high sulfur capacity, and has great recycling value.

[0004] In order to make full use of the waste heat and effective chemical components of the hot cast residue slag, many domestic and foreign enterprises have carried out the work of returning the hot cast residue slag to the converter smelting or LF furnace refining. While realizing the recycling of the hot cast residue slag, the hot cast residue steel water is effectively recovered, the metal yield is increased, the addition amount of slag materials in the converter smelting or LF furnace smelting process is reduced, the smelting cycle is shortened, and the electrode heating time is reduced, etc., thereby reducing the production cost.

[0005] However, when using hot cast residue slag in the converter smelting or LF furnace refining process, it is often restricted by factors such as smelting steel grade, slag amount, desulfurization, etc. At the same time, to a certain extent, it disrupts the normal production rhythm and brings certain difficulties to production organization. Therefore, the recovery rate and recovery times of hot cast residue slag are relatively low, and the recovery amount is small, resulting in a large part of the hot cast residue slag being directly discharged, far from meeting the demand for realizing the recycling of all hot cast residue slag. Summary of the Invention

[0006] Aiming at the deficiencies in the existing recycling of hot cast residue slag, the present invention provides a method for recycling hot cast residue slag of low-carbon aluminum-killed steel in an argon blowing station. While realizing the recycling of hot cast residue slag, operations such as "heating", "temperature rising", making white slag, making foamed slag, etc. are carried out on the low-carbon aluminum-killed molten steel in the argon blowing station, and it does not need to go through LF furnace refining treatment, achieving the purpose of reducing production cost. The technical solution adopted by the present invention is as follows:

[0007] A method for recycling hot cast residue slag of low-carbon aluminum-killed steel in an argon blowing station, the method comprising the following steps:

[0008] (1) After tapping from the converter, the ladle is moved into the argon blowing station to the treatment position for feeding aluminum wire, and then the bottom blowing of argon is maintained with a large flow rate for stirring. After the wire feeding is completed, aluminum pellets are scattered in batches on the slag surface, and after 1 minute, limestone is added in batches on the slag surface;

[0009] (2) The ladle car is moved out, and the hot casting residue is poured into the ladle, and the bottom blowing of argon is maintained with medium stirring and a bright surface;

[0010] (3) After the ladle car is moved into the treatment position, a carburant is evenly scattered on the slag surface in batches, and the bottom blowing of argon is maintained with a large flow rate for stirring;

[0011] (4) After 3 minutes of bottom blowing argon stirring, lime is added, and the molten lime coexists with the foamy slag, and the bottom blowing of argon is maintained with a medium flow rate for stirring to form an emulsified slag;

[0012] (5) 2 minutes after the formation of the emulsified slag, aluminum pellets are sprinkled on the slag surface, and the bottom blowing of argon is maintained with a soft blowing of a micro flow rate for at least 5 minutes to form a white slag;

[0013] (6) The ladle leaves the station and goes to the continuous casting platform for pouring.

[0014] The target of the converter smelting end point is controlled according to [C]≤0.06% and tapping temperature≥1630°C.

[0015] In step (1), the wire feeding amount is controlled according to the [Als] content in the steel of 300 - 600 ppm.

[0016] In steps (1) and (3), the bottom blowing argon gas flow rate is controlled at 450 - 600 NL / min.

[0017] In step (1), the amount of aluminum pellets scattered is 0.4 - 0.6 kg / t of steel.

[0018] In step (1), the limestone addition amount is 0.5 - 1.2 kg / t of steel, and the limestone particle size is 20 - 40 mm.

[0019] In step (3), the carburant addition amount is 0.4 - 0.6 kg / t of steel.

[0020] In step (4), the lime addition amount is 1.0 - 2.0 kg / t of steel; the bottom blowing argon gas flow rate is controlled at 200 - 400 NL / min.

[0021] In step (5), the aluminum pellet addition amount is 0.10 - 0.15 kg / t of steel.

[0022] In step (5), the bottom blowing argon gas flow rate is controlled at 50 - 100 NL / min.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention makes full use of the characteristics of hot cast residue, such as high temperature and good pre-melting property, combines with the bottom blowing argon stirring system in the argon blowing station, the large amount of heat generated by the aluminum deoxidation reaction, the thermal decomposition of limestone, and the generation of CO2 gas by the carbon-oxygen reaction, etc., to achieve the purpose of making foamed slag in the argon blowing station.

[0025] (2) Making full use of the characteristic that the thermal conductivity of foamed slag is poor, while feeding aluminum wire, foamed slag treatment is carried out, and the heat released by the aluminum-oxygen reaction is fully utilized, so as to achieve the "heating" and "temperature rising" treatment of molten steel without electrode heating.

[0026] (3) Making full use of the principles of metallurgical kinetics and metallurgical thermodynamics, a certain amount of lime is added in the later stage of the formation of foamed slag, and an emulsified slag is formed by the coexistence of the melting of lime and foamed slag, effectively reducing the temperature drop during the soft blowing process. At the same time, it creates good conditions for quickly making white slag in the argon blowing station, and realizes that low-carbon aluminum-killed steel can be directly cast by the argon blowing station without going through LF furnace refining treatment. Specific embodiments

[0027] The present invention will be described in detail below in conjunction with embodiments.

[0028] The capacity of the converter in the following embodiments is 120t, and the steel grade is SWRM6.

[0029] Embodiment 1

[0030] A method for recycling hot cast residue of low-carbon aluminum-killed steel in an argon blowing station, comprising the following steps:

[0031] (1) Converter end control conditions: [C]: 0.05%, [P]: 0.008%, tapping temperature: 1635°C; after tapping, the ladle is moved into the treatment position of the argon blowing station to feed 200m of aluminum wire, the bottom blowing argon flow rate is adjusted to 500NL / min, and then 60kg of aluminum pellets are scattered in two batches on the slag surface. After 1min, 100kg of limestone is added in three batches on the slag surface, and the [Als] content in the steel is 0.042%;

[0032] (2) The ladle car is moved out, and all the cast residue is recycled into the ladle;

[0033] (3) After the ladle car is moved into the treatment position, 60kg of carburant is scattered in two batches on the slag surface, the bottom blowing argon flow rate is adjusted to 500NL / min, and stirred for 3min;

[0034] (4) Add 120kg of lime, adjust the bottom blowing argon flow rate to 300NL / min, and stir for 2min;

[0035] (5) Sprinkle 10 kg of aluminum pellets on the slag surface, adjust the bottom argon flow rate to 100 NL / min, and soft blow for 5 minutes before tapping. At this time, the slag surface is smooth, white or yellow, the slag basicity ≥ 5.0, the Al2O3 content in the slag: 20% - 30%, and the MnO + FeO content ≤ 1.5%.

[0036] (6) Carry out pouring on the continuous casting platform.

[0037] Example 2

[0038] A method for recycling hot cast residue slag of low-carbon aluminum-killed steel in the argon blowing station, comprising the following steps:

[0039] (1) Converter end-point control conditions: [C]: 0.04%, [P]: 0.006%, tapping temperature: 1640 °C; after tapping, the ladle is moved into the treatment position of the argon blowing station to feed 210 m of aluminum wire, adjust the bottom argon flow rate to 450 NL / min, then sprinkle 55 kg of aluminum pellets on the slag surface in two batches, and add 90 kg of limestone on the slag surface in three batches after 1 minute. The [Als] content in the steel is 0.046%;

[0040] (2) The ladle car is moved out, and all the cast residue slag is recycled into the ladle;

[0041] (3) After the ladle car is moved into the treatment position, sprinkle 50 kg of carburizer on the slag surface in two batches, adjust the bottom argon flow rate to 450 NL / min, and stir for 3 minutes;

[0042] (4) Add 150 kg of lime, adjust the bottom argon flow rate to 250 NL / min, and stir for 2 minutes;

[0043] (5) Sprinkle 15 kg of aluminum pellets on the slag surface, adjust the bottom argon flow rate to 80 NL / min, and soft blow for 5 minutes before tapping. At this time, the slag surface is smooth, white or yellow, the slag basicity ≥ 5.0, the Al2O3 content in the slag: 20% - 30%, and the MnO + FeO content ≤ 1.5%.

[0044] (6) Carry out pouring on the continuous casting platform.

[0045] Example 3

[0046] A method for recycling hot cast residue slag of low-carbon aluminum-killed steel in the argon blowing station, comprising the following steps:

[0047] (1) BOF tapping control conditions: [C]: 0.03%, [P]: 0.008%, tapping temperature: 1630°C; After tapping, the ladle is moved to the argon blowing station for treatment, and 250 m of aluminum wire is fed. The bottom argon blowing flow rate is adjusted to 600 NL / min, and then 70 kg of aluminum pellets are scattered in two batches on the slag surface. After 1 minute, 120 kg of limestone is added in three batches on the slag surface. The [Als] content in the steel is 0.046%.

[0048] (2) The ladle car is moved out, and all the remaining slag is recycled into the ladle.

[0049] (3) After the ladle car is moved to the treatment position, 70 kg of carburizer is scattered in two batches on the slag surface. The bottom argon blowing flow rate is adjusted to 600 NL / min, and stirred for 3 minutes.

[0050] (4) 180 kg of lime is added, the bottom argon blowing flow rate is adjusted to 400 NL / min, and stirred for 2 minutes.

[0051] (5) 18 kg of aluminum pellets are scattered on the slag surface. The bottom argon blowing flow rate is adjusted to 100 NL / min, and soft blown for 5 minutes and then the ladle leaves the station. At this time, the surface of the molten slag is smooth, white or yellow. The basicity of the molten slag is ≥5.0, the Al2O3 content in the slag is 20%-30%, and the MnO + FeO content is ≤1.5%.

[0052] (6) Pouring is carried out on the continuous casting platform.

[0053] Comparative Example 1

[0054] A smelting method of low-carbon aluminum-killed steel, comprising the following steps:

[0055] (1) BOF tapping control conditions: [C]: 0.05%, [P]: 0.007%, tapping temperature: 1635°C; The molten steel is hoisted to the argon blowing station.

[0056] (2) At the argon blowing station, the bottom argon blowing flow rate is adjusted to 500 NL / min. After blowing argon for 5 minutes, the molten steel is hoisted to the LF furnace.

[0057] (3) After the molten steel enters the LF furnace, the bottom argon blowing flow rate is adjusted to 300 - 500 NL / min, the lower electrode is heated for 8 minutes. During the heating process, 400 kg of lime and 60 kg of aluminum pellets are added. After the heating is completed, 280 m of aluminum wire is fed. The bottom argon blowing flow rate is adjusted to 800 NL / min. 30 kg of aluminum pellets are scattered on the slag surface to make foamed slag and white slag. After 5 minutes, the bottom argon blowing flow rate is adjusted to 100 - 200 NL / min, sampled, and the ladle leaves the station.

[0058] In this comparative example, after tapping from the converter, the molten steel enters the argon blowing station and only argon blowing operation is carried out, without corresponding slag making, deoxidation and recovery of casting residue slag operations. In the LF furnace, operations such as electrode heating, adding slag making materials for slag making, deoxidizing the slag, feeding aluminum wire, etc. are required. The process is relatively complex, the production cycle is long, and the production cost brought by electrode heating, etc. is relatively high.

[0059] Comparative Example 2

[0060] A method for recycling hot casting residue slag of a low-carbon aluminum-killed steel in an argon blowing station, comprising the following steps:

[0061] (1) Converter end-point control conditions: [C]: 0.06%, [P]: 0.009%, tapping temperature: 1636 °C; after tapping, the molten steel is hoisted to the argon blowing station.

[0062] (2) The ladle car moves out, and all the casting residue slag is recovered into the ladle;

[0063] (3) After the ladle car moves into the treatment position, the bottom argon blowing flow rate is adjusted to 300 NL / min, 220 m of aluminum wire is fed, and stirring is carried out for 2 min;

[0064] (4) 50 kg of carburizer, 300 kg of lime, and 70 kg of aluminum pellets are added, and the bottom argon blowing flow rate is adjusted to 600 NL / min, and stirring is carried out for 3 min;

[0065] (5) At this time, the surface of the molten slag is rough, no slag is formed, and it is dark yellow. The basicity of the molten slag ≥ 5.0, the content of Al2O3 in the slag: 15% - 30%, the content of MnO + FeO > 2.0%. At the same time, the temperature of the molten steel is slightly lower than the control requirement range of the argon blowing station.

[0066] (6) Pouring is carried out on the continuous casting platform.

[0067] In this comparative example, although the hot casting residue slag is recycled and used, the operation is not carried out according to the technical solution of the present invention, resulting in a relatively low temperature of the molten steel, incomplete slag formation of the slag, and no white slag formation.

[0068] The above detailed description of a method for recycling hot casting residue slag of a low-carbon aluminum-killed steel in an argon blowing station with reference to the embodiments is illustrative rather than restrictive. Several embodiments can be listed within the defined scope. Therefore, changes and modifications without departing from the general concept of the present invention should fall within the protection scope of the present invention.

Claims

1. A method for recycling hot cast residue slag of low-carbon aluminum-killed steel in an argon blowing station, characterized in that, The method includes the following steps: (1) After tapping from the converter, the ladle is moved into the argon blowing station for treatment position to feed aluminum wire, and then the bottom blowing of argon gas is maintained with large flow rate for stirring. After the wire feeding is completed, aluminum pellets are scattered batch by batch on the slag surface, and limestone is added batch by batch on the slag surface after 1 minute. (2) The ladle car is moved out, and the hot casting residue is poured into the ladle, and the bottom blowing of argon is maintained with medium stirring and bright surface. (3) After the ladle car is moved into the treatment position, the carburizer is evenly scattered batch by batch on the slag surface, and the bottom blowing of argon gas is maintained with large flow rate for stirring. (4) After 3 minutes of bottom blowing argon for stirring, lime is added, and the molten lime coexists with the foamy slag, and the bottom blowing of argon gas is maintained with medium flow rate for stirring to form an emulsified slag. (5) After 2 minutes of formation of the emulsified slag, aluminum pellets are sprinkled on the slag surface, and the bottom blowing of argon gas is maintained with a soft blowing of micro flow rate for at least 5 minutes to form a white slag. (6) The ladle leaves the station and goes to the continuous casting platform for pouring.

2. The method according to claim 1, characterized in that, The target of the end point of converter smelting is controlled according to [C] ≤ 0.06% and tapping temperature ≥ 1630 °C.

3. The method according to claim 1, characterized in that, In step (1), the wire feeding amount is controlled according to the [Als] content in the steel of 300 - 600 ppm.

4. The method according to claim 1, wherein In steps (1) and (3), the bottom blowing argon gas flow rate is controlled at 450 - 600 NL / min.

5. The method according to claim 1, characterized in that, In step (1), the adding amount of aluminum pellets is 0.4 - 0.6 kg / t of steel.

6. The method according to claim 1, wherein In step (1), the adding amount of limestone is 0.5 - 1.2 kg / t of steel, and the particle size of limestone is 20 - 40 mm.

7. The method according to claim 1, wherein In step (3), the adding amount of carburizer is 0.4 - 0.6 kg / t of steel.

8. The method according to claim 1, wherein In step (4), the adding amount of lime is 1.0 - 2.0 kg / t of steel; the bottom blowing argon gas flow rate is controlled at 200 - 400 NL / min.

9. The method according to claim 1, characterized in that In step (5), the adding amount of aluminum pellets is 0.10 - 0.15 kg / t of steel.

10. The method according to claim 1, characterized in that, In step (5), the bottom blowing argon gas flow rate is controlled at 50 - 100 NL / min.