Method for adjusting refining furnace slag melting point and viscosity of Q355B steel grade by using rare earth cerium

Abstract

The application discloses a method for adjusting the melting point and viscosity of Q355B steel refining furnace slag by using rare earth cerium, which comprises the following processes: after ladle refining is in place and heating for 10 minutes, the top slag of the ladle is ensured to be in a molten state, bauxite is used for deoxidizing operation on the top slag, and 1-1.5 kg / t of lime is added to the top slag; after the deoxidizing operation is completed, 30% content cerium-iron alloy is added, and the adding amount is controlled to be 0.3-0.4 kg / t; after the rare earth alloy is added, component fine adjustment and refining temperature adjustment processes are carried out until the end of soft blowing, and then steel casting is carried out. The application aims to provide a method for adjusting the melting point and viscosity of Q355B steel refining furnace slag by using rare earth cerium, which utilizes the combination ability of rare earth and Al2O3 to change the melting point and viscosity of the slag and simultaneously reduce the melting temperature.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, and in particular to a method for adjusting the melting point and viscosity of refining slag for Q355B steel using rare earth cerium. Background Technology

[0002] The basic components of the desulfurization slag system for Q355B carbon structural steel ladle refining are CaO-SiO2-Al2O3. To improve fluidity, some CaF2 can be added; to improve desulfurization capacity, some strong alkaline oxides can be added; to improve lining life, some MgO can be added appropriately; and to increase foaming capacity, some carbonates and foaming agents can be added.

[0003] Studies have shown that the viscosity, density, and surface tension of slag have a significant impact on the degree of slag foaming. Therefore, submerged arc refining slag must not only have good refining capabilities but also possess suitable physical properties such as viscosity, density, and surface tension to meet the requirements of slag foaming. The foaming index of slag is directly proportional to the slag viscosity and inversely proportional to the square root of surface tension and density. The optical basicity and CaF2 content of slag have a significant impact on the foaming index, while the Al2O3 content has a very small effect. When the CaO content increases and the slag basicity is high, the surface tension of the molten slag increases, and the foaming height and holding time of the molten slag will decrease accordingly. Conversely, when the CaF2 content is high, the surface tension of the molten slag decreases, and the foaming height and holding time of the molten slag will increase accordingly.

[0004] Based on the above two studies, the key factors affecting the physical properties of slag viscosity, melting point, and melting rate are the Al2O3 and CaO content in the slag. After rare earth compounds enter the slag, they react with Al2O3 to produce ReAl2O3, thus altering the Al content in the slag. The physical properties of the slag change with the Al content. In rare earth steel smelting, the rare earth element content in the slag increases with the increase of rare earth addition. Given the different Al2O3 and SiO2 contents in the slag under different deoxidation regimes, the impact of rare earths on the physical properties of the slag under different deoxidation regimes should be considered when the rare earth content increases. Summary of the Invention

[0005] The purpose of this invention is to provide a method for adjusting the melting point and viscosity of refining slag for Q355B steel using rare earth cerium. This method utilizes the bonding ability of rare earth with Al2O3 to change the melting point, viscosity, and fluidity of the slag, while simultaneously reducing the melting temperature.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] This invention discloses a method for adjusting the melting point and viscosity of refining slag for Q355B steel using rare earth cerium. The method includes the following process: After heating the ladle for 10 minutes to ensure the top slag is in a molten state, deoxidizing the top slag with bauxite and adding 1-1.5 kg / t of top slag quicklime. After the deoxidation process, 30% cerium-iron alloy is added, with the addition amount controlled at 0.3-0.4 kg / t. After the rare earth alloy is added, the composition is finely adjusted and the refining temperature is adjusted until the soft blowing process is completed before casting.

[0008] Furthermore, the addition method involves throwing the alloy at the refining sampling station.

[0009] Furthermore, after the deoxidation operation is completed, the amount of 30% cerium-iron alloy added is controlled at 0.3 kg / t.

[0010] Furthermore, after the deoxidation operation is completed, the amount of 30% cerium-iron alloy added is controlled at 0.35 kg / t.

[0011] Furthermore, after the deoxidation operation is completed, the amount of 30% cerium-iron alloy added is controlled at 0.4 kg / t.

[0012] Furthermore, with the addition of cerium-iron alloy to the slag, the viscosity of the slag decreases.

[0013] Furthermore, with the addition of cerium-iron alloy to the slag, the slag melting temperature decreases.

[0014] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0015] As the Ce content in slag increases, the melting point and viscosity properties of the slag change. Compared with Ce-free slag, the viscosity of the slag decreases at different temperatures, which helps to improve the fluidity of the slag. At the same time, the melting temperature of the slag decreases, which helps to improve the slag's solubility. Detailed Implementation

[0016] To better understand the above aspects, features, and advantages of the present invention, the present invention will be further described in detail below with reference to specific embodiments.

[0017] A method for adjusting the melting point and viscosity of refining slag for Q355B steel using rare earth cerium includes the following processes:

[0018] After the ladle is heated for 10 minutes to ensure the top slag is in a molten state, bauxite is used to deoxidize the top slag, and 1-1.5 kg / t of top slag quicklime is added. After deoxidation, 30% cerium-iron alloy is added at a controlled rate of 0.3-0.4 kg / t, via a throwing method at the refining sampling station. After the rare earth alloy is added, the composition is fine-tuned and the refining temperature is adjusted until the soft blowing process is completed before casting.

[0019] In actual production, testing revealed that under the deoxidation process for Q355B aluminum, as the Al content in the slag increases, rare earth elements combine with Al to form rare earth calcium aluminate compounds. In Q355B steel, due to the high Al content in the slag, rare earth elements primarily form Al-Ca-Ce compounds, with a small amount of Si-Ca-Ce also generated. Activity calculations of the Q355B steel slag system showed that rare earth aluminates and rare earth calcium aluminates had higher activities in the 1300-1600℃ range, while in rare earth-free slag, simple aluminates and calcium aluminates had higher activities. The calculations and analysis indicate that the addition of rare earth elements causes rare earth Ce to form rare earth compounds with CaO and Al₂O₃ in the slag, altering the activity structure of the slag components. Rare earth calcium aluminate compounds are the most abundant component in rare earth-containing slag. Changes in the elemental composition of slag affect the activity coefficient, which in turn affects the thermodynamic conditions for the precipitation of high-melting-point calcium aluminate.

[0020] With increasing Ce content, the melting temperature of Q355B steel refining slag shows a decreasing trend. This decrease in melting temperature is mainly related to the increase in Ce content. Because Q355B steel slag has a high Al content, when Ce content increases, some Al2O3 combines with Ce to form rare earth aluminates, thus reducing the amount of Al2O3 combined with CaO, resulting in a lower melting point 12CaO·7Al2O3.

[0021] Comparing the viscosity distribution range of Ce-containing Q355B steel refining slag at 1500-1600℃ with that of rare-earth-free refining slag, the viscosity distribution of the rare-earth-containing refining slag studied in this experiment ranged from 1.02 to 2.25 Pa·s, while the viscosity distribution of the rare-earth-free refining slag ranged from 1.37 to 2.4 Pa·s. This indicates that adding an appropriate amount of Ce to the refining slag can achieve good high-temperature slag fluidity. Further analysis showed that within the temperature range, the viscosity of the rare-earth-free refining slag was greater than that of the rare-earth-containing refining slag.

[0022] Tables 1 and 2 contain specific data for each embodiment.

[0023] Table 1. Viscosity variation of Ce-containing slag

[0024]

[0025] As shown in Table 1, with the increase of rare earth content, the viscosity of slag decreases at different temperatures compared with slag without Ce, which helps to improve the fluidity of slag.

[0026] Table 2 Melting Temperature of Ce-Containing Slag

[0027]

[0028] As shown in Table 2, the slag melting temperature decreases with increasing rare earth content, which helps to improve the slag's meltability.

[0029] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for adjusting the melting point and viscosity of refining slag for Q355B steel using rare earth cerium, characterized in that, The process includes the following steps: After the ladle is heated in place for 10 minutes to ensure that the top slag of the ladle is in a molten state, bauxite is used to deoxidize the top slag, and 1-1.5 kg / t of top slag quicklime is added. After the deoxidation operation is completed, 30% cerium-iron alloy is added, with the addition amount controlled at 0.3-0.4 kg / t. After the rare earth alloy is added, the composition is fine-tuned and the refining and temperature adjustment process is carried out until the soft blowing is completed and the steel is poured.

2. The method for adjusting the melting point and viscosity of refining slag for Q355B steel using rare earth cerium according to claim 1, characterized in that, The alloy is added by throwing it into the refining sampling station.

3. The method for adjusting the melting point and viscosity of refining slag for Q355B steel using rare earth cerium according to claim 1, characterized in that, After the deoxidation operation is completed, the amount of 30% cerium-iron alloy added is controlled at 0.3 kg / t.

4. The method for adjusting the melting point and viscosity of refining slag for Q355B steel using rare earth cerium according to claim 1, characterized in that, After the deoxidation process is completed, the amount of 30% cerium-iron alloy added is controlled at 0.35 kg / t.

5. The method for adjusting the melting point and viscosity of refining slag for Q355B steel using rare earth cerium according to claim 1, characterized in that, After the deoxidation operation is completed, the amount of 30% cerium-iron alloy added is controlled at 0.4 kg / t.

6. The method for adjusting the melting point and viscosity of refining slag for Q355B steel using rare earth cerium according to claim 1, characterized in that, With the addition of cerium-iron alloy to the slag, the viscosity of the slag decreases.

7. The method for adjusting the melting point and viscosity of refining slag for Q355B steel using rare earth cerium according to claim 1, characterized in that, With the addition of cerium-iron alloy to the slag, the slag melting temperature decreases.

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