Dynamic temperature regulation and dephosphorization method for converter

Abstract

The invention belongs to the technical field of steel smelting, and relates to a dynamic temperature-adjusting dephosphorization method for a converter. Comprising the following steps: S1, a primary blowing stage: controlling the oxygen supply intensity of an oxygen lance to be 3.5-4.0 Nm < 3 > / (min.t), adding lime and light-burned dolomite at the same time, adjusting the alkalinity to be 2.2-2.5, and blowing until the temperature of a molten pool reaches 1380-1420 DEG C; s2, deslagging operation is conducted, specifically, primary slag is poured out, and the TFe content in the slag is controlled to be 10-12%; s3, in a combined blowing stage, the height of an oxygen lance is adjusted to 1.8-2.2 m, the oxygen supply intensity is reduced to 2.8-3.2 Nm < 3 > / (min.t), a fluxing agent containing CaF2 is added, the alkalinity is increased to 3.0-3.5, and the final temperature is controlled to be 1480-1520 DEG C; s4, dynamic temperature regulation: regulating the addition amount of the coolant to enable the temperature fluctuation range to be less than or equal to + / -10 DEG C; and the deslagging frequency and the iron loss are reduced while the dephosphorization rate is greater than or equal to 95%.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of steel smelting and relates to a dynamic temperature adjusting dephosphorization method for a converter. BACKGROUND

[0002] The traditional converter dephosphorization process adopts single-stage blowing, and the dephosphorization rate is greatly affected by the initial phosphorus content and temperature fluctuation of the molten iron. Frequent slagging leads to prolonged production cycle, and the total iron (TFe) content in the slag is high, about 15-20%, and the iron loss is serious. SUMMARY

[0003] To achieve the above-mentioned purpose, the application provides a dynamic temperature adjusting dephosphorization method for a converter, which solves the problems existing in the prior art.

[0004] The technical scheme adopted by the application is a dynamic temperature adjusting dephosphorization method for a converter, comprising the following steps:

[0005] S1: initial blowing stage: after the molten iron is charged into the furnace, the oxygen lance oxygen supply intensity is controlled to be 3.5-4.0 Nm 3 / (min·t), and lime and light-burned dolomite are added, the basicity is adjusted to be 2.2-2.5, and the blowing is carried out until the molten pool temperature reaches 1380-1420℃;

[0006] S2: slagging operation: the initial slag is discharged, and the TFe content in the slag is controlled to be 10-12%;

[0007] S3: reblowing stage: the oxygen lance height is adjusted to be 1.8-2.2 m, the oxygen supply intensity is reduced to be 2.8-3.2 Nm 3 / (min·t), the flux containing CaF2 is added, the basicity is increased to be 3.0-3.5, and the end point temperature is controlled to be 1480-1520℃;

[0008] S4: dynamic temperature adjusting: the temperature is measured by the side gun and the furnace gas is analyzed in real time to feed back, the amount of the cooling agent is adjusted to make the temperature fluctuation range be ≤±10℃.

[0009] Further, in the S1 initial blowing stage, the mass ratio of lime to light-burned dolomite is 3:1-4:1.

[0010] Further, in the S3 reblowing stage, the CaF2 addition amount is 1.5 kg / t.

[0011] Further, in the S4 dynamic temperature adjusting, the cooling agent is ore or scrap steel.

[0012] Further preferably, the cooling agent is iron scale with a particle size of 20-50 mm, and the addition amount is 2-5 kg / t of molten steel.

[0013] The main innovation points of the application are:

[0014] ①Staged oxygen supply intensity and alkalinity coordination control;

[0015] ②Dynamic temperature adjustment technology based on real-time monitoring;

[0016] ③Reducing iron loss through slag system optimization.

[0017] The beneficial effects of the present application are: the present application realizes dephosphorization rate ≥ 95% while reducing the number of slag tapping and reducing iron loss through dynamic temperature adjustment during the smelting process. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0019] Figure 1 is a temperature-dephosphorization rate relationship curve graph; the abscissa represents temperature, and the ordinate represents dephosphorization rate. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0021] A dynamic temperature adjustment dephosphorization method for a converter, comprising the following steps:

[0022] (1) Initial blowing stage: after the molten iron is charged into the converter, the oxygen lance oxygen supply intensity is controlled to be 3.5-4.0 Nm 3 / (min·t), and lime and light-burned dolomite are added, the mass ratio of lime to light-burned dolomite is 3:1-4:1, the alkalinity is adjusted to be 2.2-2.5, and the blowing is carried out until the molten pool temperature reaches 1380-1420℃;

[0023] (2) Slag tapping operation: the initial slag is tapped out, and the TFe content in the slag is controlled to be 10-12%;

[0024] (3) Reblowing stage: the oxygen lance height is adjusted to be 1.8-2.2 m, the oxygen supply intensity is reduced to be 2.8-3.2 Nm 3 / (min·t), a flux containing CaF2 is added, the CaF2 addition amount is 1.5 kg / t, the alkalinity is increased to be 3.0-3.5, and the end point temperature is controlled to be 1480-1520℃;

[0025] (4) Dynamic temperature control: The amount of coolant added (such as ore or scrap steel) is adjusted in real time by the temperature measurement of the auxiliary gun and the analysis of the furnace gas, so that the temperature fluctuation range is ≤ ±10℃.

[0026] It should be noted that the coolant is preferably iron oxide scale with a particle size of 20-50mm, and the addition amount is 2-5kg / t of molten steel.

[0027] To further explain, such as Figure 1 As shown, the process of this invention can achieve a higher dephosphorization rate at a lower temperature compared with the traditional process.

[0028] The following examples provide further details.

[0029] Example 1:

[0030] Molten iron conditions: P content 0.138%, temperature 1250℃;

[0031] A method for dynamic temperature control and dephosphorization in a converter includes the following steps:

[0032] Initial blowing stage: After the molten iron enters the furnace, the oxygen supply intensity is 3.8 Nm. 3 / (min·t), lime addition 18kg / t, alkalinity 2.3, blowing time 8min, temperature rise to 1395℃;

[0033] Slag removal operation: After slag removal, the TFe content in the slag is 11.2%;

[0034] Re-blowing stage: Oxygen supply intensity 3.0 Nm 3 / (min·t), add CaF2 1.5kg / t, final temperature 1492℃;

[0035] Results: Spectroscopic analysis showed that the final steel had a phosphorus content of 0.005%, a dephosphorization rate of 96.4%, and a steel loss of 2.3 kg per ton.

[0036] Example 2:

[0037] Molten iron conditions: P content 0.135%, temperature 1240℃;

[0038] A method for dynamic temperature control and dephosphorization in a converter includes the following steps:

[0039] Initial blowing stage: After the molten iron enters the furnace, the oxygen supply intensity is 3.8 Nm. 3 / (min·t), lime addition 18kg / t, alkalinity 2.3, blowing time 8min, temperature rise to 1410℃;

[0040] The TFe content in the residue after slag removal was 11.4%.

[0041] Re-blow stage: oxygen supply intensity 3.0 Nm 3 (min·t), CaF2 1.5 kg / t was added, and the end point temperature was 1510℃.

[0042] Results: Through spectral detection, the P content of the end point molten steel was 0.005%, the dephosphorization rate was 96.3%, and the iron loss per ton of steel was reduced by 2.1 kg.

[0043] Comparative Example 1:

[0044] The difference from Example 1 is that after the molten iron is charged, the oxygen supply intensity is 4.5 Nm 3 (min·t), the total lime addition amount is 30 kg / t, the basicity is 4.1, and the end point temperature is 1600℃.

[0045] Results: Through spectral detection, the P content of the end point molten steel was 0.008%, and the dephosphorization rate was 85%.

[0046] Comparative Example 2:

[0047] The difference from Example 2 is that after the molten iron is charged, the oxygen supply intensity is 4.3 Nm 3 (min·t), the total lime addition amount is 33 kg / t, the basicity is 4.3, and the end point temperature is 1590℃.

[0048] Results: Through spectral detection, the P content of the end point molten steel was 0.09%, and the dephosphorization rate was 83%.

[0049] In summary, by using the technical scheme of the present application, through the synergistic control of the stage-by-stage oxygen supply intensity and basicity, a dephosphorization rate ≥95% can be achieved.

[0050] The above only describes the preferred embodiments of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A dynamic dephosphorization method for a converter, characterized by, The method comprises the following steps: S1: initial blowing stage: after the molten iron is charged into the furnace, the oxygen lance oxygen supply intensity is controlled at 3.5-4.0 Nm 3 (min·t), while adding lime and light-burned dolomite, the basicity is adjusted to 2.2-2.5, and the blowing is performed until the bath temperature reaches 1380-1420℃; S2: slag tapping operation: tap the primary slag, and control the TFe content in the slag at 10-12%; S3: Re-blow stage: adjust the oxygen lance height to 1.8-2.2 m, and reduce the oxygen supply intensity to 2.8-3.2 Nm 3 (min·t), add a flux containing CaF2, increase the basicity to 3.0-3.5, and control the end point temperature at 1480-1520℃; S4: dynamic temperature adjustment: through real-time feedback of the temperature measured by the side gun and the furnace gas analysis, the amount of the coolant added is adjusted to make the temperature fluctuation range be ≤±10℃.

2. A dynamic desulphurization method for a converter as claimed in claim 1, characterized in that, In the S1 primary blowing stage, the mass ratio of lime to light-burned dolomite is 3:1-4:

1.

3. A dynamic desulphurization method for a converter as claimed in claim 2, characterized in that, In the S3 re-blowing stage, the CaF2 addition amount is 1.5 kg / t.

4. A dynamic desulphurization method for a converter as claimed in claim 3, characterized in that, The coolant in the S4 dynamic temperature adjustment is ore or scrap steel.

5. A dynamic desulphurization method for a converter as claimed in claim 4, characterized in that, The coolant is iron oxide scale with a particle size of 20-50 mm, and the addition amount is 2-5 kg / t of molten steel.

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