Niobium-vanadium alloy and preparation method thereof

Abstract

The invention provides a preparation method of a niobium-vanadium alloy, which comprises the following steps: a) mixing niobium oxide, excessive aluminum powder, an iron source and a slag former to carry out a first aluminothermic reaction, and separating a slag phase to obtain a ferroniobium intermediate alloy; and b) mixing the ferroniobium intermediate alloy, vanadium oxide, insufficient aluminum powder, an iron source and a slag former, carrying out a second aluminothermic reaction, and separating a slag phase to obtain the niobium-vanadium alloy. The invention further provides the niobium-vanadium alloy. According to the method, niobium is firstly reduced by adopting excessive aluminum, so that Nb2O5 which is difficult to reduce is fully reacted, and the recovery rate of niobium is increased; and then insufficient aluminum is adopted for reducing vanadium, excessive aluminum is prevented from remaining in the alloy on the basis that the vanadium reduction rate is guaranteed, and the purity of the alloy is improved. Experimental results show that the niobium-vanadium alloy meeting target components can be obtained through the method, high-value elements such as niobium and vanadium can be effectively recycled, for example, the recovery rate of niobium is larger than or equal to 98%, and the recovery rate of vanadium is larger than or equal to 96%.

Description

Technical Field

[0001] This application relates to the field of alloy materials technology, and in particular to a niobium-vanadium alloy and its preparation method. Background Technology

[0002] Niobium (Nb) and vanadium (V), as microalloying elements, significantly improve the strength, toughness, and weldability of steel through mechanisms such as grain refinement, precipitation strengthening, and inhibition of recrystallization. Niobium (Nb) plays a role in grain refinement, precipitation strengthening, increasing recrystallization temperature, and improving weldability. Vanadium (V) plays a role in precipitation strengthening, solid solution strengthening, and grain refinement to improve high-temperature resistance. Therefore, to some extent, niobium (Nb) and vanadium (V) possess certain synergistic and substitution effects as alloying additives in microalloyed steels.

[0003] Ferrovanadium (FeV) and ferroniobium (FeNb) are important alloying additives in the steel industry, used to improve the strength, toughness, and corrosion resistance of steel. Ferrovanadium contains 50-80% vanadium, and its main smelting methods include carbothermic reduction, electrosilicon thermal reduction, and (electro)aluminothermic reduction, with vanadium oxide being the commonly used vanadium source. Ferroniobium typically contains 50-70% niobium, and its main preparation methods include aluminothermic reduction, electrocarbothermic reduction, and direct reduction, with niobium concentrate or niobium oxide being the commonly used niobium source. However, no existing technology discloses the preparation of niobium-vanadium alloys. Summary of the Invention

[0004] In view of this, this application provides a niobium-vanadium alloy and a method for preparing the same. The preparation method provided by this application can obtain a niobium-vanadium alloy that meets the target composition and can effectively recover high-value elements such as niobium and vanadium.

[0005] The aluminothermic reduction method is currently the mainstream process for preparing ferrovanadium and ferroniobium alloys, but the preparation method for niobium-vanadium alloys has not yet been publicly disclosed. Because niobium (Nb) and vanadium (V) have different reduction difficulties (Nb₂O₆ is more difficult to reduce than V₂O₅), mixed reduction can easily lead to problems such as low niobium recovery and uneven alloy composition. Therefore, the preparation of niobium-vanadium alloys requires solving the problems of metal recovery and composition control during the co-reduction of niobium and vanadium.

[0006] Based on this, this application provides a method for preparing a niobium-vanadium alloy, comprising the following steps:

[0007] a) Niobium oxide, excess aluminum powder, iron source and slag-forming agent are mixed to carry out the first aluminothermic reaction, and the slag phase is separated to obtain niobium-iron master alloy;

[0008] b) The niobium-iron master alloy, vanadium oxide, insufficient aluminum powder, iron source and slag-forming agent are mixed and subjected to a second aluminothermic reaction. After separating the slag phase, the niobium-vanadium alloy is obtained.

[0009] This application employs a stepwise aluminothermic reduction method, first reducing niobium and then vanadium, and controls the amount of reducing agent used in different stages to optimize metal recovery rate and alloy composition. This effectively improves the recovery rate of high-value elements, obtains niobium-vanadium alloy products that meet the target composition, and achieves the simultaneous addition of niobium and vanadium to steel, further enhancing the comprehensive mechanical properties of steel. The resulting products can be widely used in high-end steel products in aerospace, marine engineering and other fields.

[0010] This application prepares niobium-vanadium alloys using niobium oxide, aluminum powder, iron source, slagging agent, and vanadium oxide as raw materials. In some specific implementations, the niobium oxide is preferably Nb₂O₅. In some specific implementations, the vanadium oxide is preferably V₂O₅ or V₂O₃, more preferably V₂O₅. This application does not impose any special restrictions on the aluminum powder, but its purity is preferably above 98%. In some specific implementations, the iron source is preferably iron filings. In some specific implementations, the slagging agent is one or both of CaO and MgO, preferably CaO.

[0011] This application first involves mixing niobium oxide, excess aluminum powder, an iron source, and a slagging agent to undergo a first aluminothermic reaction. After separating the slag phase, a niobium-iron master alloy is obtained. Compared to vanadium oxide, niobium oxide is more difficult to reduce. This application employs an aluminothermic reaction to reduce niobium oxide under conditions of excess aluminum to ensure that the niobium content in the product meets the requirements. Specifically, the aluminum ratio for the first aluminothermic reaction in this application is 1.10–1.50, preferably 1.15–1.45, to ensure that the niobium oxide is fully reduced to niobium. Those skilled in the art will understand that the aluminum ratio refers to a multiple of the amount of aluminum required for the theoretical stoichiometric coefficient of the niobium oxide aluminothermic reduction process. For example, an aluminum ratio of 1.10–1.50 means that the actual amount of Al added is 1.10–1.50 times the amount of aluminum required for its theoretical stoichiometric coefficient. In some specific implementations, the amount of the slagging agent added is 10%–20% of the theoretical slag production, preferably 12%–18%. In some specific implementations, the temperature of the first aluminothermic reaction is 1800℃~2000℃, preferably 1850℃~1950℃.

[0012] After the first aluminothermic reaction is completed, the slag phase is separated to obtain a niobium-iron master alloy. In some specific implementations, the slag phase is an Al2O5-CaO-MgO slag system.

[0013] After obtaining the niobium-iron master alloy, it is mixed with vanadium oxide, insufficient aluminum powder, iron source, and slag-forming agent to undergo a second aluminothermic reaction. After separating the slag phase, the niobium-vanadium alloy is obtained. During the second aluminothermic reaction, the insufficient aluminum powder prevents excessive aluminum residue. In some specific implementations, the aluminum ratio for the second aluminothermic reaction is 0.60–0.95, preferably 0.65–0.90, ensuring that the vanadium oxide is fully reduced to vanadium while avoiding aluminum residue. Those skilled in the art will understand that the aluminum ratio in this step refers to a multiple of the amount of aluminum required for the theoretical stoichiometric coefficient of the vanadium oxide aluminothermic reduction process. For example, an aluminum ratio of 0.60–0.95 means that the actual amount of Al added is 0.60–0.95 times the amount of aluminum required for its theoretical stoichiometric coefficient. In some specific implementations, the amount of slag-forming agent added is 10%–20% of the theoretical slag production, preferably 12%–18%. In some specific implementations, the temperature of the second aluminothermic reaction is 1700℃~1900℃, preferably 1750℃~1850℃.

[0014] After the second aluminothermic reaction is completed, the slag phase is separated to obtain a niobium-vanadium alloy. In some specific implementations, the slag phase is a low-melting-point Al2O5-V2O5-CaO-MgO slag system.

[0015] In some specific implementations, the mass ratio of the iron source in step a) to the iron source in step b) is 1 to 1.2:1 to 1.2, preferably 1:1, that is, the iron source is added uniformly during the two aluminothermic reactions.

[0016] This application also provides a niobium-vanadium alloy comprising: 30 wt% to 60 wt% Nb; 20 wt% to 40 wt% V and the balance Fe;

[0017] The alloy contains ≤1.0 wt% Al.

[0018] In some specific implementations, the niobium-vanadium alloy comprises: 35 wt% to 50 wt% Nb; 25 wt% to 40 wt% V and the balance Fe;

[0019] The alloy contains ≤0.8wt% Al.

[0020] The niobium-vanadium alloy provided in this application has a uniform composition and a synergistic effect on improving the mechanical properties of steel. It can be used as an additive for steel in high-end fields such as aerospace and marine engineering.

[0021] This application employs an excess of aluminum to first reduce niobium, ensuring the complete reaction of the difficult-to-reduce Nb₂O₅ and improving niobium recovery. Then, a deficiency of aluminum is used to reduce vanadium, ensuring a high vanadium reduction rate while avoiding excess aluminum residue in the alloy, thus improving alloy purity. Experimental results show that the method provided in this application can obtain niobium-vanadium alloys that meet the target composition and can effectively recover high-value elements such as niobium and vanadium, for example, niobium recovery ≥98% and vanadium recovery ≥96%. Detailed Implementation

[0022] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0023] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0024] It should be understood that the order of steps or the sequence of actions is not important as long as this application remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0025] The use of any and all instances or exemplary language such as “e.g.” or “including” herein is merely intended to better illustrate the application and does not constitute a limitation on the scope of the application unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of this application.

[0026] Furthermore, the numerical ranges and parameters used to define this application are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any value inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise explicitly stated, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately." Here, "approximately" generally means an actual value within plus or minus 10%, 5%, 1%, or 0.5% of a particular value or range.

[0027] This application provides a method for preparing a niobium-vanadium alloy, comprising the following steps:

[0028] a) Niobium oxide, excess aluminum powder, iron source and slag-forming agent are mixed to carry out the first aluminothermic reaction, and the slag phase is separated to obtain niobium-iron master alloy;

[0029] b) The niobium-iron master alloy, vanadium oxide, insufficient aluminum powder, iron source and slag-forming agent are mixed and subjected to a second aluminothermic reaction. After separating the slag phase, the niobium-vanadium alloy is obtained.

[0030] This application employs an excess of aluminum to first reduce niobium, ensuring the complete reaction of the difficult-to-reduce Nb₂O₅ and improving niobium recovery. Then, a deficiency of aluminum is used to reduce vanadium, ensuring a high vanadium reduction rate while avoiding excess aluminum residue in the alloy, thus improving alloy purity. Experimental results show that the method provided in this application can obtain niobium-vanadium alloys that meet the target composition and can effectively recover high-value elements such as niobium and vanadium, for example, niobium recovery ≥98% and vanadium recovery ≥96%.

[0031] This application also provides a niobium-vanadium alloy comprising: 30 wt% to 60 wt% Nb; 20 wt% to 40 wt% V and the balance Fe;

[0032] The alloy contains ≤1.0 wt% Al.

[0033] The niobium-vanadium alloy provided in this application has a uniform composition and a synergistic effect on improving the mechanical properties of steel. It can be used as an additive for steel in high-end fields such as aerospace and marine engineering.

[0034] The present application is further illustrated below with reference to embodiments. The scope of protection of the present application is not limited to the following embodiments.

[0035] Example 1

[0036] Taking the preparation of Nb40V40Fe alloy as an example:

[0037] Step 1: Mix 100kg Nb2O5, 37kg aluminum powder (aluminum ratio 1.10), 17kg iron filings and 7kg CaO (10% of theoretical slag content), and react at 1800℃ to obtain a niobium-iron master alloy with a theoretical Nb content of 80%.

[0038] Step 2: Add 125kg V2O5, 59kg aluminum powder (aluminum ratio 0.95), 17kg iron filings and 11kg CaO (10% of theoretical slag content) to the intermediate alloy obtained in Step 1 and mix. React at 1700℃ to obtain FeNbV alloy with theoretical Nb content of 40%, V content of 40% and Fe balance.

[0039] Example 2

[0040] Taking the preparation of Nb40V40Fe alloy as an example:

[0041] Step 1: Mix 100kg Nb2O5, 44kg aluminum powder (aluminum ratio 1.30), 17kg iron filings and 10.5kg CaO (15% of theoretical slag content), and react at 1900℃ to obtain a niobium-iron master alloy with a theoretical Nb content of 80%.

[0042] Step 2: Add 125kg V2O5, 52kg aluminum powder (aluminum ratio 0.84), 17kg iron filings and 16.5kg CaO (15% of theoretical slag content) to the intermediate alloy obtained in Step 1 and mix. React at 1800℃ to obtain FeNbV alloy with theoretical Nb content of 40%, V content of 40% and Fe balance.

[0043] Example 3

[0044] Taking the preparation of Nb40V40Fe alloy as an example:

[0045] Step 1: Mix 100kg Nb2O5, 51kg aluminum powder (aluminum ratio 1.50), 17kg iron filings and 14kg CaO (20% of theoretical slag content), and react at 2000℃ to obtain a niobium-iron master alloy with a theoretical Nb content of 80%.

[0046] Step 2: Add 125kg V2O5, 45kg aluminum powder (aluminum ratio 0.73), 17kg iron filings and 22kg CaO (20% of theoretical slag content) to the intermediate alloy obtained in Step 1 and mix. React at 1900℃ to obtain FeNbV alloy with theoretical Nb content of 40%, V content of 40% and Fe balance.

[0047] Comparative Example

[0048] Using the same raw materials and proportions as in Example 1, and simultaneously mixing 100 kg Nb2O5, 125 kg V2O5, 96 kg aluminum powder (aluminum ratio 1.0), 34 kg iron filings and 17 kg CaO (10% of the theoretical slag content), the mixture was subjected to an aluminothermic reduction reaction at 1800 °C. After the reaction, a FeNbV alloy with a theoretical Nb content of 40%, a V content of 40%, and the balance of Fe was obtained.

[0049] The Nb and V contents in the smelting slags obtained in the examples and comparative examples, as well as the Nb, V, and Al contents in the alloys, were analyzed using ICP and chemical titration. The yields of Nb and V were calculated according to the following methods:

[0050] Nb = Nb content in slag × Amount of slag in the first stage of smelting ÷ Nb content added × 100%.

[0051] V = V content in slag × Amount of slag in the second stage of smelting ÷ Input V content × 100%.

[0052] The results are shown in Table 1, which presents the niobium-vanadium alloys and yields provided in the embodiments and comparative examples of this application.

[0053] Table 1. Niobium-vanadium alloys and yields provided in the embodiments and comparative examples of this application.

[0054]

[0055] As shown in Table 1, the method provided in this application can obtain niobium-vanadium alloys that meet the target composition, with low Al content, and can effectively recover high-value elements such as niobium and vanadium, with a high recovery rate.

[0056] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and application concept of this application, should be included within the scope of protection of this application.

Claims

1. A method for preparing a niobium-vanadium alloy, comprising the following steps: a) Niobium oxide, excess aluminum powder, iron source and slag-forming agent are mixed to carry out the first aluminothermic reaction, and the slag phase is separated to obtain niobium-iron master alloy; b) The niobium-iron master alloy, vanadium oxide, insufficient aluminum powder, iron source and slag-forming agent are mixed and subjected to a second aluminothermic reaction. After separating the slag phase, the niobium-vanadium alloy is obtained.

2. The preparation method according to claim 1, characterized in that, The aluminum ratio for the first aluminothermic reaction is 1.10 to 1.50; The aluminum coefficient for the second aluminothermic reaction is 0.60 to 0.

95.

3. The preparation method according to claim 1 or 2, characterized in that, The niobium oxide is Nb2O5; the vanadium oxide is V2O5 or V2O3.

4. The preparation method according to claim 1 or 2, characterized in that, The slag-forming agent is one or both of CaO and MgO.

5. The preparation method according to claim 4, characterized in that, The amount of slag-forming agent added in step a) is 10% to 20% of the theoretical slag production; In step b), the amount of slag-forming agent added is 10% to 20% of the theoretical slag production.

6. The preparation method according to claim 1 or 2, characterized in that, The temperature of the first aluminothermic reaction is 1800℃~2000℃; The temperature of the second aluminothermic reaction is 1700℃~1900℃.

7. The preparation method according to claim 1 or 2, characterized in that, The purity of the aluminum powder is above 98%.

8. The preparation method according to claim 1 or 2, characterized in that, The mass ratio of the iron source in step a) to the iron source in step b) is 1-1.2:1-1.

2.

9. A niobium-vanadium alloy, comprising: 30wt% to 60wt% Nb; 20wt%–40wt% V and balance Fe; The alloy contains ≤1.0 wt% Al.

10. The niobium-vanadium alloy according to claim 9, characterized in that, include: 35wt%–50wt% Nb; 25wt%–40wt% V and balance Fe; The alloy contains ≤0.8wt% Al.

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