A method for refining residual elements sb to be precipitated in solid phase

Abstract

This invention provides a method for the solid-phase precipitation of residual element Sb during the refining process. By first alloying the molten steel with Ca and then with Ce, the residual element Sb precipitates in solid form during the refining process, thereby achieving the goal of efficiently removing residual element Sb from the steel.

Description

Technical Field

[0001] This invention relates to the field of steel refining technology, and more particularly to the field of removing residual elements from steel during the refining process. Background Technology

[0002] With the continuous increase in my country's scrap steel production, using scrap steel as raw material to produce steel products through electric arc furnace smelting can significantly reduce carbon emissions and achieve green steel production. However, with the increasing number of scrap steel recycling cycles, residual elements such as antimony (Sb) accumulate in the steel, causing segregation and grain boundary aggregation during continuous casting solidification, and also bringing many adverse effects on product performance. If it can be removed during the refining process, the problem of excessive Sb can be fundamentally solved. One of the key issues in the efficient removal of residual Sb during the refining process is to precipitate it as a solid phase in the molten steel, thereby removing it by floating to the refining slag or adsorbing it onto the inner wall of the ladle.

[0003] Therefore, it is essential to provide a method for the solid-phase precipitation of residual element Sb from the refining process. Summary of the Invention

[0004] To efficiently remove residual element Sb during refining, it is necessary to precipitate it in solid form within the molten steel. This invention provides a method for precipitating residual element Sb in solid form by first alloying the molten steel with calcium (Ca) and then with cerium (Ce) during the refining process.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a method for the solid-phase precipitation of residual element Sb during the refining process. The method includes: after the composition of the steel grade being refined is adjusted, sequentially performing Ca alloying treatment and Ce alloying treatment on the molten steel.

[0006] Furthermore, the method specifically includes: S1, after the composition of the steel grade being refined is adjusted, adding a Ca alloy to the molten steel and mixing it evenly; S2, adding a Ce alloy to the molten steel and mixing it evenly to obtain molten steel in which the residual element Sb precipitates in a solid phase; wherein, the amount of Ca added in the Ca alloy is 0.1 kg / -2.0 kg / t steel; the amount of Ce added in the Ce alloy is 0.01 kg / -2.0 kg / t steel. That is, the amount of Ca alloy added, converted to pure Ca, is 0.1 kg / -2.0 kg / t steel; the amount of Ce alloy added, converted to pure Ce, is 0.01 kg / -2.0 kg / t steel.

[0007] Furthermore, the molten steel is alloyed under the condition that the dissolved O content is less than 150 ppm and the S content is less than 200 ppm.

[0008] Furthermore, in S1, the Ca alloy includes one or more of metallic Ca, Ca-Mg, Ca-Si, and Ca-Al alloys; the Ca alloy is added by means of wire feeding and / or direct addition of Ca alloy blocks.

[0009] Furthermore, in S1, the mixing is carried out by bottom-blowing gas stirring, and the bottom-blowing gas includes one or more of Ar, N2, and CO2 gases.

[0010] Furthermore, the bottom-blown gas is stirred for 3-15 minutes.

[0011] Furthermore, the blowing flow rate of the bottom-blown gas agitator is 50-500 NL / min.

[0012] Furthermore, in S2, the Ce alloy includes one or more of Ce-Fe alloy, Ce-Al alloy, and Ce-Mg alloy; the Ce alloy is fed in the manner of wire feeding and / or direct feeding of Ce alloy blocks.

[0013] Furthermore, in S2, the mixing is carried out by bottom-blowing gas stirring, and the bottom-blowing gas includes one or more of Ar, N2, and CO2 gases.

[0014] Furthermore, in S2, the bottom-blown gas is stirred for 3-15 minutes.

[0015] Furthermore, in S2, the blowing flow rate of the bottom-blown gas agitator is 50-500 NL / min.

[0016] Compared with the prior art, the technical solution provided by the present invention has at least the following advantages: (1) In addition to further desulfurizing the molten steel, the Ca alloying of the present invention produces CaS, a high-melting-point phase, which can act as a heterogeneous nucleation site for the precipitation of residual element Sb in the molten steel, thus promoting the precipitation of residual element Sb in the steel. In addition, Ce and S also have a strong bonding force, and Ca alloying can enhance the effect of Ce.

[0017] (2) After Ca alloying of the Sb-containing molten steel, no residual Sb precipitates appeared in the steel. Further Ce alloying of the molten steel promoted the precipitation of residual Sb in the steel using CaS as nucleation sites, forming a Ca-Sb-Ce composite phase. High-temperature laser confocal in-situ analysis verified that the Sb-containing phase was a solid phase at the steelmaking temperature.

[0018] (3) Compared with the existing technical solutions, the present invention realizes the precipitation of residual element Sb in the molten steel in the form of solid phase, which can greatly improve the removal efficiency of residual element Sb. Attached Figure Description

[0019] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments, and unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0020] Figure 1 This is a typical surface distribution diagram of Sb-containing phase elements in the steel after Ca and Ce alloying in Example 1; Figure 2 This refers to the morphological changes of the Sb-containing phase during the heating process of the high-temperature laser confocal microscope in Example 1. Figure 3 This is an elemental distribution diagram of the floating matter on the surface of molten steel in Example 1; Figure 4 This is a surface distribution diagram of the elements on the inner wall of the refractory material in Example 1; Figure 5 This is a schematic diagram of the Ca and Ce treatment of molten steel provided by the present invention.

[0021] In the diagram, 1-steel ladle, 2-refining slag, 3-molten steel, 4-Ca alloy line, 5-Ce alloy line. Detailed Implementation

[0022] The inventors' research revealed a lack of studies on the precipitation behavior of residual element Sb in steel during the refining process. Relevant studies include Sun Guilin's doctoral dissertation, "Basic Research on the Precipitation Behavior of Residual Elements Tin and Antimony in Steel," and Chen Zihong's doctoral dissertation, "Basic Research on the Control of Residual Element Antimony in X80 Pipeline Steel." The first dissertation found Sb-containing phase precipitation in a 5.0% Sb alloy in a water-cooled sample at 1600℃, but no Sb-containing phase precipitation was observed in Fe-Sb alloys with 0.5% and 1.5% Sb contents under the same conditions. The second dissertation established a microscopic segregation model for residual element Sb during steel solidification, explored the existence forms of residual element Sb in steel and its influence on mechanical properties, and analyzed the thermodynamics of Sb removal from molten steel under reduced pressure treatment and a CaO-SiO2-Al2O3 refining slag system containing CaC2. However, it did not address the study of the precipitation behavior of residual element Sb during the refining process.

[0023] Patent CN115505679A discloses a steelmaking method for removing residual antimony from steel. This method involves repeatedly feeding calcium wire to ensure that the [Ca] content in the molten steel is ≥0.0020%, allowing residual [Sb] in the steel to react with [Ca] during the refining process. The patent states: "After the pure calcium wire is fed into the molten steel, it rapidly vaporizes. Some larger calcium bubbles quickly rise to the steel-slag interface, while other smaller calcium bubbles slowly rise and fully react with the antimony in the steel. Therefore, by feeding pure calcium wire in small batches after the molten steel enters the plant, maintaining a certain calcium content in the molten steel, the purpose of removing residual antimony can be achieved." However, it does not mention the precipitation of Sb-containing phases in the molten steel. Furthermore, experiments conducted by this invention have shown that simply feeding calcium wire into the molten steel does not cause the precipitation of residual Sb in the steel.

[0024] In view of this, the present invention proposes a method of first alloying the molten steel with Ca and then alloying it with Ce, so that the residual element Sb precipitates out in solid form during the refining process, thereby achieving the purpose of efficiently removing the residual element Sb from the steel.

[0025] The present invention will now be described in detail with reference to specific embodiments.

[0026] Example 1 This embodiment provides a method for solid-phase precipitation of residual element Sb during the refining process, using 20CrMnTi steel. The method specifically includes the following steps: S1. After the composition of the steel grade is adjusted, the molten steel is alloyed with Ca under the condition that the dissolved O content in the steel is less than 150 ppm and the S content is less than 200 ppm. After the Ca alloy is added, the bottom-blown gas is stirred for 5 minutes with Ar as the bottom-blown gas and a blowing flow rate of 200 NL / min.

[0027] S2. Then, Ce alloying is performed on the molten steel. After the Ce alloying is completed, Ar is used as the bottom blowing gas and the blowing flow rate is 100 NL / min to stir the bottom blowing gas for 8 minutes to obtain the molten steel in which the residual element Sb is precipitated in solid phase.

[0028] In S1, the types of Ca alloys include, but are not limited to, metallic Ca, Ca-Mg, Ca-Si, and Ca-Al alloys. The methods of adding Ca alloys include, but are not limited to, wire feeding and direct addition of Ca alloy blocks. The Ca alloy is converted to pure Ca, and the amount of Ca added is 0.5 kg / t of steel.

[0029] In S2, the types of Ce alloys include, but are not limited to, Ce-Fe alloys, Ce-Al alloys, and Ce-Mg alloys. The Ce alloys are added in ways including, but not limited to, wire feeding and direct addition of Ce alloy blocks. The Ce alloy is converted to pure Ce, and the Ce addition amount is 0.5 kg / t steel.

[0030] Reference Figure 5 The ladle 1 contains molten steel 3 and refining slag 2, with the refining slag 2 positioned above the molten steel 3. In the method for solid-phase precipitation of residual element Sb during the refining process provided by this invention, Ca alloy wire 4 is first fed into the molten steel 3 and the composition is homogenized; then Ce alloy wire is fed in, and the composition is homogenized again, resulting in Sb precipitating in solid form.

[0031] Example 2 This embodiment provides a method for solid-phase precipitation of residual element Sb during the refining process, using 42CrMo steel. The method includes the following steps: S1. After the composition of the steel grade is adjusted, the molten steel is alloyed with Ca under the condition that the dissolved O content in the steel is less than 150 ppm and the S content is less than 200 ppm. After the Ca alloy is added, the bottom-blown gas is stirred for 3 minutes with N2 as the bottom-blown gas and a blowing flow rate of 50 NL / min.

[0032] S2. Then, Ce alloying is performed on the molten steel. After the Ce alloying is completed, the bottom-blown gas is stirred for 15 minutes with N2 as the bottom-blown gas and a blowing flow rate of 200 NL / min to obtain the molten steel in which the residual element Sb is precipitated in solid phase.

[0033] The amount of Ca added is 0.1 kg / t steel. The amount of Ce added is 1 kg / t steel. Other conditions are the same as in Example 1, and will not be repeated here.

[0034] Example 3 This embodiment provides a method for solid-phase precipitation of residual element Sb during the refining process. The steel grade is LX72A, and the method includes the following steps: S1. After the composition of the steel grade is adjusted, the molten steel is alloyed with Ca under the condition that the dissolved O content in the steel is less than 150 ppm and the S content is less than 200 ppm. After the Ca alloy is added, the bottom-blown gas is stirred for 10 min with CO2 as the bottom-blown gas and a blowing flow rate of 150 NL / min.

[0035] S2. Then, Ce alloying is performed on the molten steel. After the Ce alloying is completed, the bottom-blown gas is stirred for 5 minutes with CO2 as the bottom-blown gas and a blowing flow rate of 150 NL / min to obtain the molten steel in which the residual element Sb is precipitated in solid phase.

[0036] The amount of Ca added is 0.5 kg / t steel. The amount of Ce added is 0.2 kg / t steel. Other conditions are the same as in Example 1 and will not be repeated here.

[0037] Comparative Example 1 Comparative Example 1 was performed in accordance with the patent with publication number CN115505679A, that is, only Ca treatment was applied to the molten steel.

[0038] Table 1 Comparison of operating parameters for each embodiment and Comparative Example 1

[0039] Taking Example 1 as an example, after only Ca alloying treatment of 20CrMnTi steel, no Sb-containing phase precipitation was observed. However, after further Ce alloying, a large amount of Sb-containing phase appeared in the steel. This Sb-containing phase mainly consisted of Sb-Ca-Ce, and contained small amounts of Al and O. The elemental distribution was as follows: Figure 1 As shown, CaS, Ca3Sb2, Al2O3, CeO2, and Ce2O2S are all high-melting-point phases, which are beneficial to... Figure 1 Further in-situ analysis of the Sb-containing phase using high-temperature laser confocal microscopy revealed that at 1526℃, the molten steel surrounding the Sb-containing phase had already begun to melt, while the Sb-containing phase remained solid. Once the molten steel had completely melted, the Sb-containing phase floated on the surface. The morphological changes of the Sb-containing phase during the sample heating process are shown below. Figure 2 As shown, it can be determined that this type of Sb-containing phase is a solid phase at the steelmaking temperature. After the molten steel melts, it is cooled at a rate of 500℃ / min. Then, scanning electron microscopy combined with energy dispersive spectroscopy (EDS) is used to analyze the floating matter on the surface of the molten steel and the inner wall of the refractory material. It was found that both the floating matter and the sidewall of the refractory material contain Sb element, as shown in the results. Figure 3 and Figure 4 As shown, this demonstrates that alloying Sb-containing molten steel with Ca followed by Ce alloying can cause the residual element Sb to precipitate in solid form, and can promote the efficient removal of residual element Sb from the steel through flotation and adsorption onto the inner wall of the refractory material.

[0040] Furthermore, analysis of the results after processing in Examples 2 and 3 yielded similar conclusions to those in Example 1, namely, that performing Ca alloying followed by Ce alloying on Sb-containing molten steel can cause the residual element Sb to precipitate in solid form.

[0041] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of the present invention. Any person skilled in the art can make their own modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for solid-phase precipitation of residual element Sb from a refining process, characterized in that, The method includes: after the composition of the steel grade is adjusted, the molten steel is subjected to Ca alloying treatment and Ce alloying treatment in sequence, which promotes the precipitation of residual element Sb in the steel with CaS as nucleation particles, forming a Ca-Sb-Ce composite phase, and obtaining molten steel in which residual element Sb is precipitated in solid phase.

2. The method for solid-phase precipitation of residual element Sb in the refining process according to claim 1, characterized in that, The method specifically includes: S1. After the composition of the steel grade being smelted has been adjusted, add Ca alloy to the molten steel and mix thoroughly. S2. Add Ce alloy to the molten steel and mix evenly to obtain molten steel in which residual element Sb precipitates in solid phase. The Ca alloy, converted to pure Ca, is added at a rate of 0.1 kg / t to 2.0 kg / t of steel; the Ce alloy, converted to pure Ce, is added at a rate of 0.01 kg / t to 2.0 kg / t of steel.

3. The method for solid-phase precipitation of residual element Sb in the refining process according to claim 2, characterized in that, The molten steel is then alloyed under conditions where the dissolved oxygen content is less than 150 ppm and the sulfur content is less than 200 ppm.

4. The method for solid-phase precipitation of residual element Sb in the refining process according to claim 2, characterized in that, In S1, the Ca alloy includes one or more of metallic Ca, Ca-Mg, Ca-Si, and Ca-Al alloys; The Ca alloy is added by means of wire feeding and / or direct addition of Ca alloy blocks.

5. The method for solid-phase precipitation of residual element Sb in the refining process according to claim 2, characterized in that, In S1, the mixing is carried out by bottom-blowing gas stirring, and the bottom-blowing gas includes one or more of Ar, N2, and CO2 gases.

6. The method for solid-phase precipitation of residual element Sb in the refining process according to claim 5, characterized in that, The bottom-blown gas is stirred for 3-15 minutes.

7. The method for solid-phase precipitation of residual element Sb in the refining process according to claim 5, characterized in that, The blowing flow rate of the bottom-blown gas agitator is 50-500 NL / min.

8. The method for solid-phase precipitation of residual element Sb in the refining process according to claim 2, characterized in that, In S2, the Ce alloy includes one or more of Ce-Fe alloy, Ce-Al alloy, and Ce-Mg alloy; The Ce alloy is fed in via wire feeding and / or direct feeding of Ce alloy blocks.

9. The method for solid-phase precipitation of residual element Sb in the refining process according to claim 2, characterized in that, In S2, the mixing method is bottom-blown gas stirring, and the bottom-blown gas includes one or more of Ar, N2, and CO2 gases.

10. The method for solid-phase precipitation of residual element Sb in the refining process according to claim 9, characterized in that, In S2, the bottom-blowing gas stirring time is 3-15 min; the bottom-blowing gas stirring flow rate is 50-500 NL / min.

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