Preparation method of ultralow-nitrogen-content high-ferrovanadium

Abstract

The invention provides a preparation method of ultralow-nitrogen-content high-vanadium iron. The preparation method comprises the following steps that S1, silicon iron powder is laid at the bottom of high-vanadium iron preparation equipment; s2, burdening according to the composition proportion of the high-vanadium iron, and electrifying the burdened raw materials for arcing and smelting; and S3, after smelting is finished, electrifying is stopped, then a refining agent is blown to the slag layer, submerged arc electrifying heating continues after blowing is finished, then nitrogen is removed from the slag surface, and finally obtained high-vanadium iron is quenched. In the preparation method of the ultralow-nitrogen-content high-ferrovanadium, the sulfur load and the carbon load in a ferrovanadium system are reduced by adopting a high-proportion low-sulfur flake vanadium furnace burden and further combining the means of strengthening slag refining, shortening the electrifying smelting time and the like, and meanwhile, submerged arc electrifying heating is performed in a slag layer so as to reduce the ionization effect of a graphite electrode arc on nitrogen in air; therefore, the nitrogen content in the ferrovanadium alloy is reduced, and finally the N content in the ferrovanadium is smaller than or equal to 0.04%.

Description

Technical Field

[0001] The present invention relates to the technical field of ferrovanadium preparation, and in particular to a method for preparing ferrovanadium with ultra-low nitrogen content and high content. Background Art

[0002] The effect of nitrogen on steel is a double-edged sword; for example: for high-quality low-nitrogen steel varieties, the presence of nitrogen in the steel will have an adverse effect on the performance of the steel. It will not only reduce the high-temperature plasticity and toughness of the steel, but also work together with hydrogen to cause scarring and subcutaneous bubbles in the calm steel, increasing the chance of subcutaneous cracks in the steel after rolling. Therefore, when producing low-nitrogen steel, the nitrogen content in the steel should be reduced as much as possible.

[0003] During the final slag enrichment process of ferrovanadium alloy smelting, nitrogen injection is often used to reduce the vanadium content in the slag and increase vanadium yield. During this injection process, nitrogen not only serves as a carrier for the powdered refining flux but also directly agitates the molten pool. Nitrogen primarily enters ferrovanadium via nitrogen gas, a nitrogen source. Conventional alloy standards do not specify nitrogen content, but some specialty steel producers, such as Japan's Hitachi and Germany's GFE, have explicitly mandated that high-vanadium ferrovanadium contain less than 0.05%. Given that downstream customers have historically rarely placed nitrogen content requirements on high-vanadium ferrovanadium, national and international standards do not consider nitrogen an impurity. To meet customer needs and seize market opportunities, the development of ultra-low nitrogen content high-vanadium ferrovanadium production processes is becoming increasingly urgent.

[0004] In order to achieve the regulation of nitrogen content in ferrovanadium alloy, many methods are used in the prior art, for example: Chinese patent application number CN202410635160.7 discloses a method for controlling the narrow fluctuation of the main element composition of high ferrovanadium and ferrovanadium alloy, the main purpose of which is to improve the stability of the main element composition; Chinese patent application number CN202210871110.X discloses a method for simultaneously reducing the P and Mn contents in ferrovanadium alloy, reducing the P and Mn impurity contents in ferrovanadium by pretreatment of raw materials; Chinese patent application number CN202310666322.9 discloses a method for controlling the aluminum content in ferrovanadium alloys and ferrovanadium alloys. This method reduces aluminum impurities in the form of inclusions in the alloy through precise batching and temperature control. Chinese patent application number CN202410631396.3 discloses a silicon control method for ferrovanadium alloy smelting. This method, through improved furnace lining quality, a rational charge structure, and ignition flash sintering to form a high-melting-point, dense sintered layer, prevents liquid silicates in the magnesia refractory from entering the ferrovanadium smelting system. These patents primarily control fluctuations in the composition of conventional impurities (Al, Si, P, Mn) and the main element V in the alloy, improving the product quality of high-vanadium ferrovanadium products. However, neither patent addresses the control of nitrogen content in the alloy nor does it measure nitrogen content.

[0005] In view of the above problems, it is of great significance to provide a method for controlling the nitrogen content in vanadium-ferroalloy. Summary of the Invention

[0006] The technical problem solved by the present invention is to provide a method for preparing high-vanadium ferrovanadium with ultra-low nitrogen content. The high-vanadium ferrovanadium prepared by the preparation method provided in this application reduces the nitrogen content in the ferrovanadium without affecting the vanadium yield.

[0007] In view of this, the present application provides a method for preparing ultra-low nitrogen content high vanadium ferro, comprising the following steps:

[0008] S1. Laying ferrosilicon powder on the bottom of the equipment for preparing high vanadium iron;

[0009] S2. Mixing the raw materials according to the composition ratio of high-vanadium iron, and then energizing and arc-smelting the mixed raw materials; the mass ratio of flake vanadium to vanadium trioxide in the mixed raw materials is (2-8):1, S≤0.03wt% and C≤0.01wt% in the flake vanadium, and S≤0.03% and C≤0.01wt% in the vanadium trioxide;

[0010] S3. After the smelting is completed, the power is turned off and the refining agent is sprayed into the slag layer. After the spraying is completed, the submerged arc is continued to be heated, and then nitrogen is removed from the slag surface. Finally, the high vanadium iron is quenched by water.

[0011] In some specific embodiments, in step S1, the thickness of the ferrosilicon powder is 2 to 10 mm; and / or, in step S2, the thickness of the raw materials of the batch on the surface of the ferrosilicon powder is 400 mm to 1600 mm.

[0012] In some specific embodiments, in step S2, the raw materials of the batching further include aluminum beans, steel scraps and lime, and the mass ratio of flake vanadium, vanadium trioxide, aluminum beans, steel scraps and lime in the raw materials is (2-8):1:(1-4):(1-2):(1-2).

[0013] In some specific embodiments, in step S3, the time of the electric arc smelting is 10 to 30 minutes, and the content of residual vanadium in the slag after the electric arc smelting is 1.5%±0.2% to 2.5%±0.2%.

[0014] In some specific embodiments, the refining agent includes one or more of aluminum powder, iron powder, and ferrosilicon powder.

[0015] In some specific embodiments, in step S3, the submerged arc heating time is 10 to 30 minutes, and the content of residual vanadium in the slag after the submerged arc heating is 0.6%±0.2% to 1.0%±0.2%.

[0016] In some specific embodiments, in step S3, the time for removing nitrogen is 1 to 5 minutes.

[0017] In some specific embodiments, the water quenching method is specifically as follows: cooling the obtained high-vanadium iron to 1300-1500° C., removing the formed slag layer, and then spraying water for cooling.

[0018] In some specific embodiments, the high-vanadium iron is FeV80.

[0019] In some specific embodiments, the nitrogen content in the high-vanadium iron is ≤0.04 wt %.

[0020] The present application provides a method for preparing high-vanadium ferrovanadium with ultra-low nitrogen content. The method comprises the following steps: first, ferrosilicon powder is laid on the bottom of a high-vanadium ferrovanadium preparation device; then, the raw materials are mixed according to the composition ratio of the high-vanadium ferrovanadium; and the mixed raw materials are energized and arc-smelted. After the smelting is completed, the power is stopped and a refining agent is sprayed into the slag layer. After the spraying is completed, submerged arc heating is continued, and nitrogen is removed from the slag surface. Finally, the obtained high-vanadium ferrovanadium is water quenched. In the preparation process of high-vanadium ferrovanadium with ultra-low nitrogen content, the present application adopts a high-proportion low-sulfur flake vanadium charge, strengthens slag refining, shortens the electric smelting time, and reduces the sulfur load and carbon load in the system. At the same time, electric heating is performed in the slag layer to reduce the ionization effect of the graphite electrode arc on nitrogen in the air, thereby reducing the nitrogen content in the ferrovanadium. In addition, during the cooling process, the surface temperature of the alloy is controlled during water quenching to form a water film isolation layer on the alloy surface to avoid carburization caused by contact with air, thereby further reducing the nitrogen content in the ferrovanadium. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a graph showing the analysis results of N, C, and S contents in high-vanadium ferroalloy prepared using prior art;

[0022] Figure 2 This is a diagram showing the analysis results of the N, C, and S contents in the high-vanadium ferroalloy prepared by the present invention. DETAILED DESCRIPTION

[0023] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0024] In view of the demand for ultra-low nitrogen content (nitrogen content ≤ 0.05%) of high-vanadium ferroalloys in the prior art, the present application provides a method for preparing high-vanadium ferro with ultra-low nitrogen content. The method controls the source of nitrogen, nitriding rules, and control difficulties in high-vanadium ferro in the conventional nitrogen-carried powder injection refining process in a step-by-step manner, and regulates the key elements that restrict the nitrogen content in the V-Fe-Al-Si-NCS multi-component system. The method achieves the preparation of high-vanadium ferro with ultra-low nitrogen content, meets customer needs, and increases the market share of high-vanadium ferro. Specifically, the embodiment of the present invention discloses a method for preparing high-vanadium ferro with ultra-low nitrogen content, comprising the following steps:

[0025] S1. Laying ferrosilicon powder on the bottom of the equipment for preparing high vanadium iron;

[0026] S2. Mixing the raw materials according to the composition ratio of high-vanadium iron, and then energizing and arc-smelting the mixed raw materials; the mass ratio of flake vanadium to vanadium trioxide in the mixed raw materials is (2-8):1, S≤0.03wt% and C≤0.01wt% in the flake vanadium, and S≤0.03% and C≤0.01wt% in the vanadium trioxide;

[0027] S3. After the smelting is completed, the power is turned off and the refining agent is sprayed into the slag layer. After the spraying is completed, the submerged arc is continued to be heated, and then nitrogen is removed from the slag surface. Finally, the high vanadium iron is quenched by water.

[0028] In the preparation process of ultra-low nitrogen content high vanadium iron, the present application first lays ferrosilicon powder on the bottom of the high vanadium iron preparation equipment to form a ferrosilicon powder layer. Specifically, the thickness of the ferrosilicon powder is 2 to 10 mm, more specifically, the thickness of the ferrosilicon powder is 3 to 8 cm, and more specifically, the thickness of the ferrosilicon powder is 4 to 6 mm. The purpose of laying the ferrosilicon powder on the bottom of the present application is to avoid oxidation of the ferrosilicon powder during the injection process to reduce the nitrogen content in the vanadium iron alloy. At the same time, it can also increase the initial silicon content in the smelting alloy melt, increase the activity of Al in the alloy, and help reduce the loss of vanadium in the slag. The thickness of the above-mentioned ferrosilicon powder is to ensure uniform distribution and help prevent excessive segregation of silicon impurities and excessive silicon impurities.

[0029] The present application then prepares the materials according to the composition ratio of high vanadium iron. In this stage, the materials adopt a thick material layer, high proportion, low sulfur, low carbon flake vanadium charge structure, that is, the thickness of the raw materials of the materials on the surface of the ferrosilicon powder layer is 400-1600mm, specifically, the thickness of the raw materials of the materials on the surface of the ferrosilicon powder layer is 600-1300mm, more specifically, the thickness of the raw materials of the materials on the surface of the ferrosilicon powder layer is 800-1100mm. The flake vanadium charge structure is specifically that the mass ratio of flake vanadium and vanadium trioxide is (2-8):1, specifically, the mass ratio of flake vanadium and vanadium trioxide is (3-6):1, more specifically, the mass ratio of flake vanadium and vanadium trioxide is (4-5):1; S in the flake vanadium is ≤0.03wt%, C ≤0.01wt%, S in the vanadium trioxide is ≤0.03%, C ≤0.01wt%; specifically, the S content in the flake vanadium is The amount of S is 0.01%, 0.02%, and 0.03%, the content of C is 0.008%, 0.005%, and 0.01%, the content of S in the vanadium trioxide is 0.01%, 0.02%, and 0.03%, and the content of C is 0.008%, 0.005%, and 0.01%; the content of sulfur and carbon in the above-mentioned flake vanadium and vanadium trioxide is controlled to reduce the load of C and S in the system, thereby helping to reduce the nitrogen content in the ferrovanadium alloy. The design method of the thick material layer and high-proportion flake vanadium charge structure of the present application can utilize the high thermal effect of the exothermic reaction process of flake vanadium and aluminum to quickly achieve preliminary separation of slag and gold, reduce the amount of heat and power-on time, and at the same time, the slag layer formed under the above-mentioned charge system is thicker, which can directly avoid open arc smelting and quickly achieve slag submerged arc smelting, so that the thermal efficiency of converting electrical energy into thermal energy is improved and the nitrogen ionization effect is weakened. Furthermore, the raw materials formulated according to the composition of high-vanadium iron in this application also include aluminum beans, steel scraps and lime, and the mass ratio of flake vanadium, vanadium trioxide, aluminum beans, steel scraps and lime is (2~8):1:(1~4):(1~2):(1~2); specifically, the mass ratio of flake vanadium, vanadium trioxide, aluminum beans, steel scraps and lime is (3.5~5):1:(2.5~3.5):(1.5~1.8):(1.5~1.8); in a specific embodiment, the mass ratio of flake vanadium, vanadium trioxide, aluminum beans, steel scraps and lime is 2:1:1:1:1, 8:1:4:2:2 or 5:1:2.5:1.5:1.5.

[0030] The batched raw materials are then subjected to electric arc smelting. The electric arc smelting process follows procedures well known to those skilled in the art and is not particularly limited in this application. In this application, the electric arc smelting time is 10 to 30 minutes, specifically 15 to 20 minutes. The residual vanadium content in the slag after the electric arc smelting is 1.5% ± 0.2% to 2.5% ± 0.2%.

[0031] After the above-mentioned electric arc smelting is completed, the power is stopped and a refining agent is sprayed into the slag layer for refining to further reduce the content of residual vanadium in the slag. In the above process, the specific operation method of spraying the refining agent is carried out according to methods well known to those skilled in the art, and this application does not impose any special restrictions on this. The refining agent may specifically include one or more of aluminum powder, iron powder and ferrosilicon powder, specifically one selected from aluminum powder, iron powder and ferrosilicon powder. After the spraying is completed, submerged arc heating is continued to further control the content of vanadium in the slag. The heating time is 10 to 30 minutes, specifically 15 to 20 minutes. The content of residual vanadium in the slag after the heating is 0.6% ± 0.2% to 1.0% ± 0.2%.

[0032] According to the conventional operation of those skilled in the art, the slag is left to cool and the furnace is dismantled. However, the present application has made adjustments to this process, specifically: nitrogen is removed from the slag surface, and the obtained high-vanadium iron is water quenched. More specifically, holes are punched on the slag surface to allow residual nitrogen to be discharged for 1 to 3 minutes. When the high-vanadium iron is cooled to 1300 to 1500°C, water spray cooling is performed to block the nitriding process in the cooling link and further reduce the nitrogen content in the vanadium iron alloy.

[0033] The above method provided in the present application is applicable to high-vanadium iron, and more specifically to FeV80.

[0034] The applicants analyzed the mechanism of nitrogen absorption in high-vanadium ferroalloys and discovered that during electric heating, nitrogen in the air is extremely active around the arc. Ionized by the high-temperature arc, nitrogen comes into contact with vanadium alloy droplets. According to the nitrogen dissolution reaction, at a constant nitrogen partial pressure, the solubility of nitrogen in the alloy liquid is related to the nitrogen dissolution reaction constant and its activity coefficient, in accordance with Sievert's law. Nitrogen solubility in the alloy liquid also increases with increasing temperature. Thermodynamic analysis shows that active nitrogen can undergo a series of transformation reactions with various trace substances in the melt, such as carbon and sulfur, during the solid-liquid separation process. Within a suitable temperature range, highly active substances such as V, C, and S act as catalysts for nitrogen to participate in the reactions and enter the ferrovanadium alloy. When the C and S loadings in the system are high, the solubility of nitrogen in the alloy liquid increases. During the solidification phase of the alloy liquid after nitrogen absorption, diffusion in the liquid boundary layer becomes the limiting factor, resulting in poor denitrification kinetics, leading to generally elevated N, C, and S in the final ferrovanadium alloy. Therefore, the present invention proposes to control the sulfur load and carbon load in the system by adopting a high-proportion low-sulfur flake vanadium charge structure system, strengthening slag refining, and shortening the single-furnace power smelting time during the reaction period, without affecting the normal use of the carrier gas powder spraying system. Electric heating in the thick slag layer reduces the ionization effect of the graphite electrode arc on nitrogen in the air, further reduces the nitrogen content in the alloy, and ultimately stably controls it to below 0.05%; further, the present application controls the surface temperature of the alloy during water quenching, forms a water film isolation layer on the alloy surface as early as possible, and avoids nitriding caused by contact with air.

[0035] In order to further understand the present invention, the preparation method of the ultra-low nitrogen content high vanadium iron provided by the present invention is described in detail below with reference to the examples. The protection scope of the present invention is not limited by the following examples.

[0036] Example 1

[0037] A layer of ferrosilicon powder with a thickness of about 2mm is laid on the furnace bottom in advance; a 1500mm thick material layer and a high-proportion flake vanadium charge structure are adopted, wherein the mass ratio of flake vanadium to vanadium trioxide is 2:1, the S content in vanadium trioxide is controlled at 0.03%, and the C content is controlled at 0.01%. The S content in flake vanadium is controlled at 0.03%, and the C content is controlled at 0.01%. Conventional ingredients are made according to the requirements of FeV80-A (the mass ratio of flake vanadium, vanadium trioxide, aluminum beans, steel chips and lime is 2:1: 1:1:1), ignite and conduct electric smelting for 10 minutes, control the residual vanadium content of the slag to 1.5%, then spray refining agent into the slag layer, continue to lower the electrode and conduct submerged arc heating for 10 minutes after the spraying, control the residual vanadium content of the slag to 0.6%±0.2%, finally perform piercing on the slag surface for 1 minute to clear the residual nitrogen, remove the upper layer of solidified corundum slag when the surface of the high vanadium ferroalloy cools to 1300℃, and force water spray cooling on the obtained alloy cake.

[0038] The alloy composition of the alloy cake obtained in this example was tested, and the results are shown in Table 1.

[0039] Example 2

[0040] A layer of ferrosilicon powder with a thickness of about 10mm is laid on the furnace bottom in advance; an 800mm thick material layer and a high proportion of flake vanadium charge structure are adopted, wherein the mass ratio of flake vanadium to vanadium trioxide is 8:1, the S content in vanadium trioxide is controlled to 0.02%, and the C content is controlled to 0.008%. The S content in flake vanadium is controlled to 0.02%, and the C content is controlled to 0.008%. Conventional ingredients are made according to the requirements of FeV80-A (the mass ratio of flake vanadium, vanadium trioxide, aluminum beans, steel chips and lime is 8:1:4: 2:2), ignite and conduct electric smelting for 30 minutes, control the residual vanadium content of the slag to 2.5%±0.2%, then spray refining agent into the slag layer, continue to lower the electrode and conduct submerged arc heating for 30 minutes after the spraying, control the residual vanadium content of the slag to 1.0%±0.2%, finally perform piercing on the slag surface for 3 minutes to clear the residual nitrogen, remove the upper layer of solidified corundum slag when the surface of the high vanadium ferroalloy cools to 1500℃, and force water spray cooling on the obtained alloy cake.

[0041] The alloy composition of the alloy cake obtained in this example was tested, and the results are shown in Table 1.

[0042] Example 3

[0043] A layer of ferrosilicon powder with a thickness of about 6mm is pre-laid on the furnace bottom. A 400mm thick material layer and a high-proportion flake vanadium charge structure are used. The mass ratio of flake vanadium to vanadium trioxide is 5:1, the sulfur content in vanadium trioxide is controlled to 0.01%, and the carbon content is controlled to 0.005%. The sulfur content in flake vanadium is controlled to 0.01%, and the carbon content is controlled to 0.005%. Conventional ingredients are prepared according to the requirements of FeV80-A (the mass ratio of flake vanadium, vanadium trioxide, aluminum beans, steel chips and lime is 5:1:2.5:1. 5:1.5), ignite and conduct electric smelting for 20 minutes, control the residual vanadium content of the slag at 2.0%±0.2%, then spray refining agent into the slag layer, continue to lower the electrode and conduct submerged arc heating for 20 minutes after the spraying, control the residual vanadium content of the slag at 0.8%±0.2%, finally perform piercing on the slag surface for 2 minutes to clear the residual nitrogen, remove the upper layer of solidified corundum slag when the surface of the high vanadium ferroalloy cools to 1400℃, and force-spray water cooling on the obtained alloy cake.

[0044] The alloy composition of the alloy cake obtained in this example was tested, and the results are shown in Table 1.

[0045] Comparative Example 1

[0046] A layer of ferrosilicon powder is laid on the bottom of the furnace in advance, with a thickness of about 2mm; a high-proportion vanadium trioxide charge structure is adopted, in which the mass ratio of flake vanadium to vanadium trioxide is 1:2, the S content in vanadium trioxide is controlled to 0.05%, the C content is controlled to 0.07%, the S content in flake vanadium is controlled to 0.04%, and the C content is controlled to 0.05%. Conventional ingredients are made according to the requirements of FeV80-A (the mass ratio of flake vanadium, vanadium trioxide, aluminum beans, steel chips and lime is 2:1:1:1:1), and a batch of thin layers (thickness 500mm) is used. After ignition, two batches of thin layers (500 mm thick) were added. After adding, the slag was smelted with electricity for 10 minutes respectively to control the residual vanadium content in the slag at 1.5%. Then, a refining agent was sprayed into the slag layer. After the spraying was completed, the electrode was lowered and heated for 10 minutes to control the residual vanadium content in the slag at 0.6% ± 0.2%. Finally, the slag surface was pierced for 1 minute to allow the residual nitrogen to be discharged. When the surface of the high-vanadium ferroalloy was cooled to 1300°C, the upper layer of solidified corundum slag was removed and the obtained alloy cake was forced to be cooled by water spray.

[0047] The alloy composition of the alloy cake obtained in this comparative example was tested, and the results are shown in Table 1.

[0048] Comparative Example 2

[0049] A layer of ferrosilicon powder with a thickness of about 2 mm is pre-laid on the furnace bottom; a 1500 mm thick material layer and a high-proportion flake vanadium charge structure are adopted, wherein flake vanadium: vanadium trioxide = 2:1, the S content in vanadium trioxide is controlled at 0.03%, and the C content is controlled at 0.01%. Conventional materials are mixed according to the requirements of FeV80-A (the mass ratio of flake vanadium, vanadium trioxide, aluminum beans, steel scraps and lime is 2:1:1:1:1), ignition is carried out for electric smelting for 10 minutes, and the residual vanadium content in the slag is controlled at 1.5%. Then, a refining agent is sprayed into the slag layer. After the spraying is completed, electrodes are lowered and heated for 10 minutes to control the residual vanadium content in the slag to 0.6%±0.2%. The slag is then left to cool and the furnace is dismantled in a conventional manner.

[0050] The alloy composition of the alloy cake obtained in this comparative example was tested, and the results are shown in Table 1.

[0051] Comparative Example 3

[0052] A layer of ferrosilicon powder with a thickness of about 2mm is laid on the furnace bottom in advance; a 1500mm thick material layer and a high proportion of flake vanadium charge structure are adopted, wherein the mass ratio of flake vanadium to vanadium trioxide is 2:1, the S content in vanadium trioxide is controlled to 0.03%, and the C content is controlled to 0.01%. The S content in flake vanadium is controlled to 0.03%, and the C content is controlled to 0.01%. Conventional ingredients are made according to the requirements of FeV80-A (the mass ratio of flake vanadium, vanadium trioxide, aluminum beans, steel chips and lime is 2:1: 1:1:1), ignite and conduct electric smelting for 10 minutes, control the residual vanadium content of the slag at 1.5%, then spray refining agent into the slag layer, continue to lower the electrode and conduct electric heating for 10 minutes after the spraying, control the residual vanadium content of the slag at 0.6%±0.2%, finally perform piercing on the slag surface for 0.5 minutes to clear the residual nitrogen, remove the upper layer of solidified corundum slag when the surface of the high vanadium ferroalloy cools to 900°C, and force-spray water cooling on the obtained alloy cake.

[0053] The alloy composition of the alloy cake obtained in this comparative example was tested, and the results are shown in Table 1.

[0054] The preparation method of the ultra-low nitrogen content high vanadium ferro of the present invention ensures that the nitrogen in the alloy is stably controlled without affecting the vanadium yield. Figure 1 and Figure 2 The influencing factors and results of nitrogen content in 20 smelting furnaces before and after the implementation of the method provided in this application are shown in Table 1. The nitrogen content detection equipment is an oxygen, nitrogen and hydrogen analyzer, and the sulfur and carbon content detection equipment is a carbon and sulfur analyzer.

[0055] Table 1 Composition data of vanadium-ferroalloys prepared in Examples and Comparative Examples

[0056]

[0057]

[0058] As can be seen from Table 1, the method provided in the present application can significantly reduce the carbon content, sulfur content and nitrogen content, and the nitrogen content meets the requirement of <0.05%. However, in Comparative Example 1, thick charge and high-flaky vanadium charge structure were not used, which affected the carbon content, sulfur content and nitrogen content. In Comparative Examples 2 and 3, no specific cooling method was used, which affected the carbon content, sulfur content and nitrogen content.

[0059] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0060] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing ultra-low nitrogen content high-vanadium ferro, comprising the following steps: S1. Laying ferrosilicon powder on the bottom of the equipment for preparing high vanadium iron; S2. Mixing the raw materials according to the composition ratio of high-vanadium iron, and then energizing and arc-smelting the mixed raw materials; the mass ratio of flake vanadium to vanadium trioxide in the mixed raw materials is (2-8):1, S≤0.03wt% and C≤0.01wt% in the flake vanadium, and S≤0.03% and C≤0.01wt% in the vanadium trioxide; S3. After the smelting is completed, the power is turned off and the refining agent is sprayed into the slag layer. After the spraying is completed, the submerged arc is continued to be heated, and then nitrogen is removed from the slag surface. Finally, the high vanadium iron is quenched by water.

2. The preparation method according to claim 1, characterized in that In step S1, the thickness of the ferrosilicon powder is 2 to 10 mm; and / or, in step S2, the thickness of the raw materials of the batch on the surface of the ferrosilicon powder is 400 mm to 1600 mm.

3. The preparation method according to claim 1, characterized in that In step S2, the raw materials of the batching further include aluminum beans, steel scraps and lime, and the mass ratio of flake vanadium, vanadium trioxide, aluminum beans, steel scraps and lime in the raw materials is (2-8):1:(1-4):(1-2):(1-2).

4. The preparation method according to claim 1, characterized in that In step S3, the time of the electric arc smelting is 10 to 30 minutes, and the content of residual vanadium in the slag after the electric arc smelting is 1.5%±0.2% to 2.5%±0.2%.

5. The preparation method according to claim 1, characterized in that The refining agent includes one or more of aluminum powder, iron powder and ferrosilicon powder.

6. The preparation method according to claim 1, characterized in that In step S3, the submerged arc heating time is 10 to 30 minutes, and the content of residual vanadium in the slag after the submerged arc heating is 0.6%±0.2% to 1.0%±0.2%.

7. The preparation method according to claim 1, characterized in that In step S3, the time for removing nitrogen is 1 to 5 minutes.

8. The preparation method according to claim 1, characterized in that The water quenching method is specifically as follows: when the obtained high-vanadium iron is cooled to 1300-1500° C., the formed slag layer is removed and then water-spray cooling is performed.

9. The preparation method according to any one of claims 1 to 8, characterized in that The high vanadium iron is FeV80.

10. The preparation method according to any one of claims 1 to 8, characterized in that: The nitrogen content in the high-vanadium iron is less than or equal to 0.04 wt%.

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