A method for preparing a high-nitrogen vanadium-containing steelmaking additive, vanadium ferro-silicon nitride

Abstract

This invention provides a method for preparing high-nitrogen-content vanadium-containing steelmaking additive silicon vanadium ferronitride, comprising the following steps: 1) mixing vanadium oxide and a carbon source at a C / O molar ratio of 0.8-1, briquetting the mixture, and then placing it in a nitrogen atmosphere for a reduction nitriding reaction at 1100-1400 °C to obtain a one-step product; 2) crushing the one-step product obtained in step 1), mixing it with a silicon source and an iron source, briquetting the mixture, and then placing it in a nitrogen atmosphere for densification treatment at 1300-1500 °C to obtain high-nitrogen-content silicon vanadium ferronitride, wherein the silicon source is ferrosilicon and / or silicon. This invention can obtain high-purity, uniformly composed, and highly dense silicon vanadium ferronitride, improving the automation level and continuous production capability of the production process.

Description

Technical Field

[0001] This invention belongs to the technical field of steelmaking additive preparation, specifically relating to a method for preparing silicon vanadium ferronitride, a high-nitrogen-content vanadium-containing steelmaking additive. Background Technology

[0002] Vanadium is an indispensable microalloying element in the metallurgical field, typically added to steel as an alloying additive to significantly improve its overall properties, such as strength, toughness, and wear resistance. Ferrovanadium nitride, a widely used new generation of vanadium-nitrogen alloy, is mainly composed of vanadium nitride and iron phases. Nitrogen promotes the more complete precipitation of vanadium in steel as nitrides, improving vanadium utilization and reducing production costs. The presence of iron helps increase alloy density and the dissolution rate of vanadium nitride, while also allowing it to more easily penetrate the slag layer during steelmaking, reducing alloy loss.

[0003] In recent years, researchers have introduced silicon into ferrovanadium nitride (FN), developing silicon nitride ferrovanadium alloys with higher nitrogen content. This alloy, by partially replacing vanadium nitride with silicon nitride, not only inherits the excellent properties of FN but also possesses new advantages: Firstly, the nitrogen content of silicon nitride can reach approximately 40%, significantly higher than that of vanadium nitride (approximately 21%), further increasing the nitrogen content of the alloy. The increased nitrogen-vanadium ratio enhances the precipitation strengthening effect of vanadium nitride in steel. Secondly, silicon itself can act as a deoxidizer and alloying element, preventing vanadium oxidation and increasing vanadium yield. Therefore, silicon ferrovanadium nitride alloys, as a novel vanadium alloy with high nitrogen content and multiple functions, show broad application prospects.

[0004] Existing silicon vanadium ferronitride is mainly prepared by the self-propagating method and the one-step carbothermal reduction nitridation method. Chinese invention patent application CN107604234 A discloses a method for preparing vanadium vanadium ferronitride using a one-step carbothermal reduction nitridation method. This method directly mixes vanadium trioxide, carbon powder, ferrosilicon, and iron powder, presses them into briquettes, and then sintersects them directly under a nitrogen atmosphere to obtain silicon vanadium ferronitride. This method involves solid-state calcination, which suffers from several problems, including incomplete reaction, insufficient nitrogen enrichment, excessive residual oxygen content, and low apparent density.

[0005] Currently, the preparation methods for vanadium ferrosilicon nitride generally have significant shortcomings. On the one hand, the chemical stability and compositional precision of vanadium in the resulting alloy products are difficult to control, and the microstructure uniformity is poor, directly affecting the quality of the final product. On the other hand, the preparation process consumes too much energy, resulting in high production costs and poor economic benefits. Therefore, there is an urgent need to develop a new, efficient, energy-saving, and controllable process for preparing vanadium ferrosilicon nitride to overcome current bottlenecks and meet the needs of large-scale industrial production. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method for preparing silicon vanadium ferronitride, a high-nitrogen-content steelmaking additive. By systematically optimizing the sintering process, the reduction nitriding process is separated from the material densification process, effectively avoiding vanadium volatilization and nitrogen loss at high temperatures, thus improving reaction efficiency and product quality. Furthermore, by systematically studying the effects of key parameters such as sintering temperature, reaction time, and carbon ratio on the product phase composition, nitrogen content, and microstructure, the optimal process is determined to achieve stable product composition, high nitrogen content, and uniform nitriding degree.

[0007] According to one aspect of the present invention, a method for preparing high-nitrogen-content vanadium-containing steelmaking additive ferrosilicon nitride is provided, comprising the following steps:

[0008] 1) Vanadium oxide and carbon source are mixed at a C / O molar ratio of 0.8 to 1 and briquetted. Then, the mixture is placed in a nitrogen atmosphere and subjected to a reduction nitridation reaction at 1100 to 1400 °C to obtain the one-step product.

[0009] 2) The product obtained in step 1) is crushed, mixed with silicon source and iron source, and then briquetted. Then it is placed in a nitrogen atmosphere and densified at 1300~1500 °C to obtain silicon vanadium iron nitride with high nitrogen content, wherein the silicon source is ferrosilicon and / or silicon.

[0010] As a preferred embodiment of the method for preparing high-nitrogen-content vanadium-containing steelmaking additive silicon vanadium ferronitride according to the present invention, the vanadium oxide includes one or more of vanadium pentoxide, vanadium dioxide, and vanadium trioxide.

[0011] As a preferred embodiment of the method for preparing silicon vanadium ferronitride, a high-nitrogen-content steelmaking additive according to the present invention, the carbon source includes one or more of flake graphite, carbon powder, and carbon black.

[0012] In a preferred embodiment of the method for preparing silicon vanadium ferronitride, a high-nitrogen-content steelmaking additive according to the present invention, the iron source includes iron powder.

[0013] As a preferred embodiment of the method for preparing silicon vanadium ferronitride, a high-nitrogen-content steelmaking additive according to the present invention, in step 1), the particle size of the mixed powder after mixing is ≤100 mesh.

[0014] As a preferred embodiment of the method for preparing high-nitrogen-content vanadium-containing steelmaking additive silicon vanadium ferronitride according to the present invention, in step 1), the mixing is specifically carried out by ball milling in a dry ball mill, the ball milling media is stainless steel balls, the ball-to-material ratio is 5:1 to 20:1, and the ball milling time is 2 to 6 hours.

[0015] As a preferred embodiment of the method for preparing high-nitrogen-content vanadium-containing steelmaking additive silicon vanadium ferronitride according to the present invention, in step 1), water is used as a binder in the briquetting process, the amount of water added is 3~5% of the mass of the mixed powder, and the pressure of the briquetting process is 50~100 MPa.

[0016] As a preferred embodiment of the method for preparing silicon vanadium ferronitride, a high-nitrogen-content steelmaking additive according to the present invention, in step 1), the reduction nitriding reaction takes 2-5 hours.

[0017] As a preferred embodiment of the method for preparing high-nitrogen-content vanadium-containing steelmaking additive silicon vanadium ferronitride according to the present invention, in step 2), the mixing is specifically carried out by ball milling in a dry ball mill, the ball milling media is stainless steel balls, the ball-to-material ratio is 5:1 to 20:1, and the ball milling time is 2 to 6 hours.

[0018] As a preferred embodiment of the method for preparing silicon vanadium ferronitride, a high-nitrogen-content steelmaking additive according to the present invention, in step 2), the particle size of the mixed powder after mixing is ≤100 mesh.

[0019] As a preferred embodiment of the method for preparing silicon vanadium ferronitride, a high-nitrogen-content steelmaking additive according to the present invention, in step 2), the pressure of the briquetting process is 50~100 MPa.

[0020] As a preferred embodiment of the method for preparing silicon vanadium ferronitride, a high-nitrogen-content steelmaking additive according to the present invention, in step 2), the densification treatment time is 2-6 hours.

[0021] According to another aspect of the present invention, a silicon vanadium iron alloy is also provided, which is prepared by any of the preceding methods, wherein the silicon vanadium iron alloy comprises, by mass, 40-70% vanadium, 12-24% nitrogen, 1-20% silicon, ≤2% carbon + oxygen, and the balance being iron; further, the carbon + oxygen is ≤1.5%.

[0022] In this invention, the amounts of silicon and iron sources added are determined based on the content of relevant components in the desired target product; the statement "particle size ≤ 100 mesh" specifically means that the powder can pass through a 100-mesh sieve. Regarding the product components, there may be trace amounts of other impurities due to differences in raw material sources, but these impurities are negligible due to their extremely low content and are therefore not reflected in the component content of this invention.

[0023] In this invention, ferrosilicon or silicon is used as the silicon source. This effectively avoids the introduction of other impurities, improving product purity, and also avoids problems such as excessively long reaction times, excessively high reaction temperatures, and uncontrollable reactions. Furthermore, the timing of adding the silicon source is particularly important. This is because silicon is a strong deoxidizing element. If the silicon source is added simultaneously with the carbon source and vanadium oxide, silicon will react preferentially with respect to carbon and vanadium oxide. The resulting silicon dioxide is chemically stable and cannot be removed in subsequent steps, remaining as an impurity and leading to a decrease in product purity. Additionally, this reaction is strongly exothermic, causing the reactants to melt, which affects the reduction of vanadium and subsequent nitriding. Moreover, the solidification of the melted reactants makes subsequent crushing more difficult, thus affecting the nitrogen content, uniformity, and density of the product. For the reasons mentioned above, this invention adds only vanadium oxide and carbon source in the first step of the reduction nitriding reaction. The above reactants can undergo reduction nitriding reaction at low temperature, that is, carbon reduces vanadium oxide to generate vanadium, and then vanadium undergoes nitriding to form vanadium nitride. Then, after the vanadium nitride is mixed evenly with silicon source and iron source, it is subjected to high-temperature densification treatment, thereby obtaining a high-purity silicon vanadium iron alloy with uniform composition.

[0024] In this invention, due to the large amount of oxygen removed during the reduction nitriding reaction, the resulting vanadium nitride is a porous material. This material is first crushed and then re-pressed into blocks, which can effectively eliminate the large number of pores formed between particles due to deoxidation, thereby making their contact more compact. Then, after the second sintering, a high-density silicon vanadium iron nitride alloy is obtained.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. This invention uses silicon or ferrosilicon as the silicon source, processes it separately from vanadium oxide and carbon source, and rationally controls the ratio of each reactant and the reaction temperature. Combined with the crushing and mixing step after the reduction nitriding reaction, it can obtain high-purity, uniformly composed and highly dense silicon vanadium iron nitride.

[0027] 2. This invention does not require a vacuum or high-pressure environment, so a pusher kiln can be used as the reaction equipment, which improves the degree of automation and continuous production capability.

[0028] 3. This invention processes each reactant in a stepwise manner, which on the one hand reduces the processing temperature of some reaction processes, thereby saving energy. On the other hand, it avoids problems such as uncontrollable reaction and strong exothermic reaction caused by preferential reaction (e.g., silicon and carbon) leading to melting of reactants, and melting of reactants caused by lower melting point (e.g., carbon and iron), thereby further improving the purity, density and uniformity of the product. Detailed Implementation

[0029] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] A method for preparing high-nitrogen-content vanadium-containing steelmaking additive silicon vanadium ferronitride includes the following steps:

[0032] 1) 39.73 g of vanadium trioxide and 8.98 g of flake graphite were mixed by ball milling (ball-to-material ratio 10:1, ball milling time 3h) to obtain a mixture with a particle size ≤100 mesh. Then, 2 g of water was added and the mixture was pressed into a block under a pressure of 60 MPa for 5 min. The block was placed in a nitrogen atmosphere and subjected to reduction nitriding treatment at 1350 ℃ for 3 h to obtain the first-step product.

[0033] 2) The product obtained in step 1) is crushed and mixed with 5 g silicon powder and 7.25 g iron powder by ball milling (ball-to-material ratio 10:1, ball milling time 3 h) to obtain a mixture with a particle size ≤100 mesh. The mixture is pressed into blocks under 60 MPa pressure for 5 min. The blocks are placed in a nitrogen atmosphere and densified at 1500 ℃ for 4 h to obtain silicon vanadium iron nitride with high nitrogen content.

[0034] The silicon nitride ferrovanadium obtained in this embodiment has a regular morphology, uniform surface color, and metallic luster, and exhibits no iron flow or adhesion. The elemental contents were determined to be: vanadium 54.0%, nitrogen 20.4%, silicon 10.1%, iron 14.3%, with the remainder being trace amounts of carbon and oxygen. The density was 5.76 g / cm³. 3 .

[0035] Example 2

[0036] A method for preparing high-nitrogen-content vanadium-containing steelmaking additive silicon vanadium ferronitride includes the following steps:

[0037] 1) 47.81 g of vanadium trioxide and 10.34 g of carbon powder were mixed by ball milling (ball-to-material ratio 15:1, ball milling time 2h) to obtain a mixture with a particle size ≤100 mesh. Then, 1.5 g of water was added and the mixture was pressed into a block under a pressure of 80 MPa for 5 min. The block was placed in a nitrogen atmosphere and subjected to reduction nitriding treatment at 1200℃ for 2 h to obtain the first-step product.

[0038] 2) The product obtained in step 1) is crushed and mixed with 4.67 g of ferrosilicon with a silicon content of 75% and 1.08 g of iron powder by ball milling (ball-to-material ratio 15:1, ball milling time 2 h) to obtain a mixture with a particle size ≤100 mesh. The mixture is pressed into blocks under 80 MPa pressure for 5 min. The blocks are placed in a nitrogen atmosphere and densified at 1350℃ for 3 h to obtain high nitrogen content silicon vanadium ferronitride.

[0039] The silicon vanadium iron nitride obtained in this embodiment has a regular morphology, uniform surface color with a metallic luster, and no iron flow or adhesion. The elemental contents were determined to be: vanadium 65.4%, nitrogen 21.1%, silicon 7.3%, iron 4.5%, with the remainder being trace amounts of carbon and oxygen, and a density of 5.49 g / cm³. 3 .

[0040] Example 3

[0041] A method for preparing high-nitrogen-content vanadium-containing steelmaking additive silicon vanadium ferronitride includes the following steps:

[0042] 1) 38.38 g of vanadium trioxide and 11.15 g of carbon powder were mixed by ball milling (ball-to-material ratio 5:1, ball milling time 4h) to obtain a mixture with a particle size ≤100 mesh. Then, 2 g of water was added and the mixture was pressed into a block under a pressure of 75 MPa for 5 min. The block was placed in a nitrogen atmosphere and subjected to reduction nitriding treatment at 1400 ℃ for 3 h to obtain the first-step product.

[0043] 2) The product obtained in step 1) is crushed and mixed with 7.5 g silicon powder and 11.75 g iron powder by ball milling (ball ratio 5:1, ball milling time 4 h) to obtain a mixture with a particle size ≤100 mesh. The mixture is pressed into blocks under a pressure of 75 MPa for 5 min. The blocks are placed in a nitrogen atmosphere and densified at 1500℃ for 4 h to obtain silicon vanadium iron nitride with high nitrogen content.

[0044] The silicon vanadium iron nitride obtained in this embodiment has a regular morphology, uniform surface color with a metallic luster, and no iron flow or adhesion. The elemental contents were determined to be: vanadium 43.0%, nitrogen 17.4%, silicon 14.6%, iron 23.5%, with the remainder being trace amounts of carbon and oxygen, and a density of 6.03 g / cm³. 3 .

[0045] Comparative Example 1

[0046] A method for preparing high-nitrogen-content vanadium-containing steelmaking additive silicon vanadium ferronitride includes the following steps:

[0047] 1) 39.73 g of vanadium trioxide, 8.98 g of flake graphite and 5 g of silicon powder were mixed by ball milling (ball-to-material ratio 10:1, ball milling time 3 h) to obtain a mixture with a particle size ≤100 mesh. Then, 2 g of water was added and the mixture was pressed into a block under a pressure of 60 MPa for 5 min. The block was placed in a nitrogen atmosphere and subjected to reduction nitriding treatment at 1350 ℃ for 3 h to obtain the first-step product.

[0048] 2) The product obtained in step 1) is crushed and mixed with 7.25 g of iron powder by ball milling (ball-to-material ratio 10:1, ball milling time 3 h) to obtain a mixture with a particle size ≤100 mesh. The mixture is pressed into blocks under 60 MPa pressure for 5 min. The blocks are placed in a nitrogen atmosphere and densified at 1500 ℃ for 4 h to obtain silicon vanadium iron nitride.

[0049] The elemental contents of the silicon vanadium iron nitride obtained in this comparative example were determined to be: vanadium 50.8%, nitrogen 8.4%, silicon 9.4%, iron 14.1%, with the remainder being carbon and oxygen, and a density of 4.96 g / cm³. 3 Compared to Example 1, this comparative example adds a silicon source in the first step, while keeping the rest unchanged. The carbon and oxygen content in the final product increases, while the nitrogen content and density decrease.

[0050] Comparative Example 2

[0051] A method for preparing high-nitrogen-content vanadium-containing steelmaking additive silicon vanadium ferronitride includes the following steps:

[0052] 1) 39.73 g of vanadium trioxide and 12.99 g of flake graphite were mixed by ball milling (ball-to-material ratio 10:1, ball milling time 3 h) to obtain a mixture with a particle size ≤100 mesh. Then, 2 g of water was added and the mixture was pressed into a block under a pressure of 60 MPa for 5 min. The block was placed in a nitrogen atmosphere and subjected to reduction nitriding treatment at 1350 ℃ for 3 h to obtain the first-step product.

[0053] 2) The product obtained in step 1) is crushed and mixed with 10.70 g of silica powder and 7.25 g of iron powder by ball milling (ball-to-material ratio 10:1, ball milling time 3 h) to obtain a mixture with a particle size ≤100 mesh. The mixture is pressed into blocks under a pressure of 60 MPa for 5 min. The blocks are placed in a nitrogen atmosphere and densified at 1500 ℃ for 4 h to obtain silicon vanadium iron nitride.

[0054] The elemental contents of the silicon vanadium iron nitride obtained in this comparative example were determined to be: vanadium 50.4%, nitrogen 9.7%, silicon 9.3%, iron 13.5%, with the remainder being carbon and oxygen, and a density of 5.33 g / cm³. 3Compared to Example 1, this comparative example replaced the silicon source with silicon dioxide and added the corresponding amount of carbon in the first step at the same carbon-oxygen ratio, while keeping the rest unchanged. The carbon and oxygen content in the final product increased, while the nitrogen content and density decreased.

[0055] Comparative Example 3

[0056] A method for preparing high-nitrogen-content vanadium-containing steelmaking additive silicon vanadium ferronitride includes the following steps:

[0057] 1) 39.73 g of vanadium trioxide and 8.98 g of flake graphite were mixed by ball milling (ball-to-material ratio 10:1, ball milling time 3 h) to obtain a mixture with a particle size ≤100 mesh. Then, 2 g of water was added and the mixture was pressed into a block under a pressure of 60 MPa for 5 min. The block was placed in a nitrogen atmosphere and subjected to reduction nitriding treatment at 1500 ℃ for 3 h to obtain the first-step product.

[0058] 2) The product obtained in step 1) is crushed and mixed with 5 g silicon powder and 7.25 g iron powder by ball milling (ball-to-material ratio 10:1, ball milling time 3 h) to obtain a mixture with a particle size ≤100 mesh. The mixture is pressed into blocks under 60 MPa pressure for 5 min. The blocks are placed in a nitrogen atmosphere and densified at 1500 ℃ for 4 h to obtain silicon vanadium iron nitride.

[0059] The elemental contents of the silicon vanadium iron nitride obtained in this comparative example were determined to be: vanadium 54.4%, nitrogen 14.8%, silicon 11.7%, iron 14.3%, with the remainder being carbon and oxygen, and a density of 5.16 g / cm³. 3 Compared to Example 1, this comparative example increased the first-step sintering temperature to 1500 °C, while keeping the rest unchanged. The carbon and oxygen content in the final product increased, while the nitrogen content and density decreased.

[0060] It should be noted that, based on the above embodiments of the present invention, those skilled in the art can fully realize the scope of the independent claims and dependent claims of the present invention, and the implementation process and methods are the same as those in the above embodiments; and the parts of the present invention not described in detail belong to the well-known technology in the art. However, the protection scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing high-nitrogen-content vanadium-containing steelmaking additive silicon vanadium ferronitride, characterized in that, Includes the following steps: 1) Vanadium oxide and carbon source are mixed at a C / O molar ratio of 0.8 to 1 and briquetted. Then, the mixture is placed in a nitrogen atmosphere and subjected to a reduction nitridation reaction at 1100 to 1400 °C to obtain the one-step product. 2) The product obtained in step 1) is crushed, mixed with silicon source and iron source, and then briquetted. Then it is placed in a nitrogen atmosphere and densified at 1300~1500 °C to obtain silicon vanadium iron nitride with high nitrogen content, wherein the silicon source is ferrosilicon and / or silicon.

2. The method as described in claim 1, characterized in that, The carbon source includes one or more of flake graphite, carbon powder, and carbon black.

3. The method as described in claim 1, characterized in that, The iron source includes iron powder.

4. The method as described in claim 1, characterized in that, In step 1) and / or step 2), the particle size of the mixed powder is ≤100 mesh.

5. The method as described in claim 4, characterized in that, In step 1) and / or step 2), the mixing is specifically performed by ball milling using a dry ball mill, with stainless steel balls as the milling media, a ball-to-material ratio of 5:1 to 20:1, and a milling time of 2 to 6 hours.

6. The method according to any one of claims 1 to 5, characterized in that, In step 1), water is used as a binder in the briquetting process, and the amount of water added is 3 to 5% of the mass of the mixed powder. The pressure of the briquetting process is 50 to 100 MPa.

7. The method according to any one of claims 1 to 5, characterized in that, In step 2), the pressure of the pressing block is 50~100 MPa.

8. The method as described in any one of claims 7, characterized in that, In step 1), the time for the reduction nitridation reaction is 2-5 hours.

9. The method as described in claim 8, characterized in that, In step 2), the densification process takes 2 to 6 hours.

10. A silicon vanadium iron nitride alloy, characterized in that, The silicon vanadium iron nitride alloy is prepared by the method according to any one of claims 1 to 9, wherein the silicon vanadium iron nitride comprises, by mass, 40-70% vanadium, 12-24% nitrogen, 1-20% silicon, ≤2% carbon + oxygen, and the balance being iron.