Preparation method of high-strength vanadium-nitrogen alloy based on vanadium ammonium salt

Abstract

The invention discloses a preparation method of a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt, and relates to the technical field of vanadium-nitrogen alloy preparation. The preparation method comprises the following steps: carrying out plate-frame pressure filtration on vanadium ammonium salt, drying, adding flaky vanadium pentoxide, grinding, adding graphite, ferric oxide and water, mixing, grinding, pressing into elliptical green balls, airing, and roasting to obtain the high-strength vanadium-nitrogen alloy based on the vanadium ammonium salt. The high-strength vanadium-nitrogen alloy is produced by taking the vanadium ammonium salt as a raw material and adopting a directly-heated rotary kiln method, so that the cost is low, the method is green and environment-friendly, the compressive strength of the vanadium-nitrogen alloy green pellets is improved, and the problems of poor pelletizing performance and high crushing rate of a directly-heated rotary kiln in the traditional technology are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of vanadium-nitrogen alloy preparation, and in particular to a method for preparing a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt. Background Art

[0002] Vanadium-nitrogen alloy is an alloying additive used in steelmaking. Compared to ferrovanadium, it can save 20-40% of vanadium at the same strength level, making it a popular choice in the steel industry. The mainstream production process of vanadium-nitrogen alloy uses vanadium pentoxide and vanadium trioxide as raw materials, mixes them with graphite powder to form pellets, and then gradually roasts them in a pusher kiln under a nitrogen atmosphere, including reduction and nitriding reactions. However, the pusher kiln method has the following problems: ① Graphite crucibles are required as carriers. During the production of vanadium-nitrogen alloys, the potassium and sodium gases released easily cause the graphite to expand and pulverize. Surface coating is currently used to solve this problem, but the cost of using graphite crucibles is high and their lifespan is still short. ② The heating elements use silicon carbon rods or silicon molybdenum rods, which have relatively high heat loss and long furnace shutdown and restart cycles. ③ The sintered vanadium-nitrogen alloy easily hardens, requiring manual dispersion, making automatic continuous production difficult.

[0003] The direct-heated rotary kiln method for producing vanadium-nitrogen alloy has the advantages of continuous production, easy furnace shutdown and restart, low power consumption, and no crucible / silicon-molybdenum rod consumables. It has more cost advantages than the traditional push-plate kiln method. However, since the material moves forward dynamically in the rotary kiln, the material only has mechanical force before sintering. When vanadium pentoxide is used as the raw material, even if the compressive strength of the raw balls produced by the roller briquette machine is greater than 500N, 10-20% of powder will still be produced. In addition, when the proportion of return material added exceeds 5%, the fragmentation rate of vanadium-nitrogen alloy will increase significantly. The high powder rate is one of the key factors limiting the industrial production of this process.

[0004] In terms of raw materials, most of the existing research has focused on vanadium pentoxide and vanadium trioxide. In recent years, some studies have used ammonium vanadate as raw material and the push-plate kiln method to produce vanadium-nitrogen alloy. This process reduces the process of preparing vanadium oxide from ammonium vanadate. In theory, the cost is lower than the long process. However, in actual production, this process has low production capacity and environmental problems, and has not been converted to production. The prior art involves mixing a vanadium oxide compound with a carbonaceous reducing agent, pressing the mixture into a pelletizer, and then subjecting the mixture to a high-temperature reaction in a directly heated rotary kiln to obtain a vanadium-nitrogen alloy product, wherein the vanadium oxide is one or more of vanadium oxide, ammonium metavanadate, ammonium polyvanadate, or red vanadium in various valence states. However, when ammonium metavanadate or ammonium polyvanadate is used as a raw material and graphite is used as a reducing agent, the ammonium metavanadate or ammonium polyvanadate has very poor green ball performance of only 40-100N after being pressed into balls using a double-roller pelletizer due to its fine grains and light density. The ball is severely pulverized during the roasting process, especially in the medium-temperature stage of 800-900°C, where the compressive strength of the ball is only 20-40N, resulting in a finished product breakage rate of 30-40%. Summary of the Invention

[0005] In response to the above-mentioned deficiencies in the prior art, the present invention provides a method for preparing a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt. The method is low-cost, green and environmentally friendly, improves the compressive strength of the vanadium-nitrogen alloy green balls, and effectively solves the problems of poor ball forming performance and high crushing rate in direct-heated rotary kilns in traditional technologies.

[0006] To achieve the above object, the present invention solves the technical problem by adopting a technical solution: a method for preparing a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt, comprising the following steps: S1, vanadium ammonium salt is filtered through a plate and frame filter press, dried, and oven-dried, and then flaky vanadium pentoxide is added and ground to obtain mixture 1; S2, adding graphite and ferric oxide to the mixture 1 obtained in step S1 to obtain a mixture 2, and then adding water, mixing, grinding and pressing to obtain green balls; S3. The green balls obtained in step S2 are dried in the sun and then roasted. During the roasting, nitrogen is always introduced into the kiln head. After cooling, a vanadium-nitrogen alloy is obtained.

[0007] Furthermore, in step S1, the vanadium ammonium salt is ammonium metavanadate or ammonium polyvanadate.

[0008] Furthermore, in step S1, the moisture content after plate and frame filtration is 35-45%.

[0009] Furthermore, in step S1, the mixture is dried by compressed air until the moisture content is 20-30%.

[0010] Furthermore, in step S1, the product is dried in a belt drying kiln using direct heated rotary kiln tail gas until the moisture content is 1-5%.

[0011] Furthermore, in step S1, the product is dried in a belt drying kiln using direct heated rotary kiln tail gas until the moisture content is 1%.

[0012] Furthermore, in step S1, the temperature of the tail gas is 190-210°C.

[0013] Furthermore, in step S1, the tail gas includes dust and waste gas.

[0014] Furthermore, in step S1, the dust removal ash includes sodium oxide, potassium oxide, ferric oxide and vanadium pentoxide.

[0015] Furthermore, in step S1, in the dust removal ash, sodium oxide accounts for 15-16%, potassium oxide accounts for 9-10%, ferric oxide accounts for 7-8%, and vanadium pentoxide accounts for 40-50%.

[0016] Furthermore, in step S1, the dust ash contains 15.1% sodium oxide, 9.1% potassium oxide, 7.8% ferric oxide, and 46.3% vanadium pentoxide. Furthermore, in step S1, the waste gas includes nitrogen, carbon monoxide, carbon dioxide and ammonia.

[0017] Furthermore, in step S1, the dust ash can be directly returned to the leaching process in the sodium vanadium extraction process after being collected by the dust bag, and the vanadium resources can be extracted and utilized again; the ammonium sulfate generated after the ammonia in the exhaust gas is absorbed by sulfuric acid can be returned to the vanadium precipitation process in the sodium vanadium extraction process again, and the exhaust gas after being absorbed by sulfuric acid is discharged through an exhaust pipe with an exhaust fan, and a burner is set at the exhaust port to completely burn the carbon monoxide and then discharge the gas.

[0018] Furthermore, in step S1, the amount of flaky vanadium pentoxide added is 10-30% of the mass of the vanadium ammonium salt.

[0019] Furthermore, in step S1, the amount of flaky vanadium pentoxide added is 10-15% of the mass of the vanadium ammonium salt.

[0020] Further, in step S1, the powder is ground to a particle size of 180-200 mesh.

[0021] Furthermore, in step S1, grinding is performed using a ball mill.

[0022] The beneficial effects of adopting the above further solution are: by mixing and grinding the flaky vanadium pentoxide with the vanadium ammonium salt, the powder morphology is changed and the particle size distribution of the material is increased, thereby improving the embedding effect between the powders.

[0023] Furthermore, in step S2, the mass ratio of mixture 1, graphite and ferric oxide is 100:25-30:0.5-1.

[0024] Furthermore, in step S2, the mass ratio of mixture 1, graphite and ferric oxide is 100:28:0.5.

[0025] Furthermore, in step S2, the amount of water added is 16-22% of the mass of the second mixture.

[0026] Furthermore, in step S2, the amount of water added is 18-20% of the mass of the second mixture.

[0027] Furthermore, in step S2, the mixture is mixed and ground for 3-4 hours.

[0028] Furthermore, in step S2, during pressing, the static pressure is 5-8 MPa.

[0029] Furthermore, in step S2, the raw balls are 30-40 mm elliptical spheres.

[0030] Furthermore, in step S2, the molding machine used for pressing is a conventional powder metallurgy molding equipment with functions of automatic loading, automatic discharging and water absorption during the pressing process, and its inner cavity is designed to be a hemispherical socket.

[0031] The beneficial effect of adopting the above further solution is: improving the fluidity of the material in the rotary kiln.

[0032] Furthermore, in step S2, the angle of repose of the green ball is 16-22°.

[0033] Furthermore, in step S2, the angle of repose of the green ball is 18-20°.

[0034] Furthermore, in step S2, the moisture content of the green balls is 5-8%.

[0035] Furthermore, in step S3, the balls are naturally aired until the moisture content of the balls does not exceed 3%.

[0036] Furthermore, in step S3, the sintered product is calcined in a direct-heated rotary kiln.

[0037] Furthermore, in step S3, the length of the direct-heated rotary kiln is 10 m and the inner diameter is 300 mm.

[0038] Furthermore, in step S3, the length ratio of the preheating section, the high temperature section and the cooling section of the direct-heated rotary kiln is 4-5:5:3.

[0039] Furthermore, in step S3, the length ratio of the preheating section, the high temperature section and the cooling section of the direct-heated rotary kiln is 4:5:3.

[0040] Furthermore, in step S3, the maximum temperature of the heating section is 1500-1600°C.

[0041] Furthermore, in step S3, during calcination, the inclination angle is 1.5-3° and the rotation speed is 0.3-1 m / min.

[0042] Furthermore, in step S3, during calcination, the inclination angle is 2.5° and the rotation speed is 0.5-0.8 m / min.

[0043] Furthermore, in step S3, during the firing, nitrogen is always introduced into the kiln head.

[0044] Furthermore, in step S3, the concentration of nitrogen is 99.999%.

[0045] Furthermore, in step S3, the nitrogen flow rate is 80-120m 3 / h.

[0046] Furthermore, in step S3, the nitrogen flow rate is 90-100m 3 / h.

[0047] Furthermore, in step S3, in the direct-heated rotary kiln, the direction of nitrogen introduction is opposite to the forward direction of the material, and the tail gas formed passes through the preheating section of the rotary kiln and enters the belt drying kiln through the flue gas duct.

[0048] Furthermore, in step S3, during firing, a slight positive pressure of 10-20 Pa is maintained in the kiln.

[0049] Further, in step S3, the temperature is cooled to 65-75°C.

[0050] Furthermore, in step S3, the mixture is cooled to 70°C.

[0051] Furthermore, in step S3, the calcination is carried out for 20-25 hours.

[0052] The high-strength vanadium-nitrogen alloy based on vanadium ammonium salt is prepared by adopting the preparation method of the high-strength vanadium-nitrogen alloy based on vanadium ammonium salt.

[0053] The present invention has the following beneficial effects: 1. This invention uses vanadium ammonium salt as raw material and employs a direct-heated rotary kiln, an energy-saving process. This eliminates the need for a vanadium pentoxide preparation step, significantly reducing production costs. Compared to conventional pusher kiln processes, the cost per ton of product is reduced by 4,000-4,500 yuan.

[0054] 2. The present invention adds flaky vanadium pentoxide to the vanadium ammonium salt and grinds it. The ground flaky vanadium pentoxide has irregular edges and corners, and the vanadium ammonium salt is crystalline, which makes the powder morphology diverse. At the same time, this method can increase the particle size distribution of the material and enhance the interlocking force between the powders during the ball pressing process, thereby significantly improving the mechanical strength of the green ball and making the green ball strength as high as 1800-3000N.

[0055] 3. This invention utilizes a mold press for pelletizing. Compared to traditional roller pelletizers, the green balls produced by this press have controllable ovality, are easier to demold, and can reduce their angle of repose, thereby increasing the material feed rate in the preheating section of the rotary kiln and preventing material pile-up. Furthermore, after static pressing, the material is evenly stressed, resulting in a denser green ball with a compressive strength exceeding 1000N, effectively avoiding the problem of green ball pulverization in the low and medium temperature sections of the rotary kiln.

[0056] 4. The high-strength vanadium-nitrogen alloy prepared by the method provided by the present invention has a vanadium content of 76-78%, a nitrogen content of 16.5-19%, a carbon content of 3.2-4.2%, and a density of 3.8-4.4 g / cm 3 , the amount of crushed materials with a particle size less than 10mm shall not exceed 5%.

[0057] 5. The present invention utilizes the dust and waste gas generated in the rotary kiln process as resources, and the entire process is green production. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 Flowchart of the present invention. DETAILED DESCRIPTION

[0059] The principles and features of the present invention are described below. The examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. In the examples, where specific conditions are not specified, conventional conditions or manufacturer-recommended conditions were used. Reagents or instruments used where the manufacturer is not specified are conventional products that can be purchased commercially.

[0060] Example 1 A high-strength vanadium-nitrogen alloy based on vanadium ammonium salt, the preparation method of which comprises the following steps: S1. The moisture content of ammonium polyvanadate after plate and frame filtration is 40%, which is dried to 25% by compressed air. In a belt drying kiln, the tail gas of a direct-heated rotary kiln is dried to a moisture content of 1%. The tail gas temperature is 200°C, and then flaky vanadium pentoxide is added and ground to a particle size of 180-200 mesh to obtain a mixture. The addition amount of the above-mentioned flaky vanadium pentoxide is 12% of the mass of ammonium polyvanadate. The above-mentioned tail gas includes dust and waste gas. The dust includes sodium oxide, potassium oxide, ferric oxide and vanadium pentoxide, of which sodium oxide accounts for 15.1%, potassium oxide accounts for 9.1%, ferric oxide accounts for 7.8%, and vanadium pentoxide accounts for 46.3%. The waste gas includes nitrogen, carbon monoxide, carbon dioxide and ammonia. After the tail gas dries the ammonium polyvanadate, the dust ash is collected by the dust bag and can be directly returned to the leaching process in the sodium vanadium extraction process to extract and utilize the vanadium resources. The ammonia in the waste gas is absorbed by sulfuric acid to generate ammonium sulfate, which can be returned to the vanadium precipitation process in the sodium vanadium extraction process. The waste gas after sulfuric acid absorption is discharged through an exhaust pipe with an exhaust fan. A burner is set at the exhaust port to completely burn the carbon monoxide and then discharge the gas. S2. Graphite and ferric oxide were added to the mixture obtained in step S1 to obtain a mixture II, wherein the mass ratio of the mixture I, graphite, and ferric oxide was 100:28:0.5. Water was then added in an amount of 19% of the mass of the mixture II. The mixture was then mixed and milled for 3.5 hours and pressed into 30-40 mm elliptical spheres in a molding press at a static pressure of 6 MPa to obtain green balls having a repose angle of 20° and a moisture content of 6%. S3, the green balls obtained in step S2 are naturally aired to a moisture content of 2%, and then roasted in a direct-heated rotary kiln for 24 hours. The length of the direct-heated rotary kiln is 10m, the inner diameter is 300mm, the length ratio of the preheating section, the heating section and the cooling section is 4:5:3, the maximum temperature of the heating section is 1550°C, and during roasting, the inclination angle is 2.5°, the rotation speed is 0.6m / min, and 99.999% nitrogen is always introduced into the kiln head, and the nitrogen inlet flow rate is 95m 3 / h, maintaining a slight positive pressure of 15Pa in the kiln, and after cooling to 70℃, a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt is obtained.

[0061] Example 2 A high-strength vanadium-nitrogen alloy based on vanadium ammonium salt, the preparation method of which comprises the following steps: S1. The moisture content of ammonium metavanadate after plate and frame filtration is 35%. It is dried to 20% by compressed air. In a belt drying kiln, the tail gas of a direct-heated rotary kiln is dried to 3% moisture content. The tail gas temperature is 190°C. Then, flaky vanadium pentoxide is added and ground to a particle size of 180-200 mesh to obtain a mixture. The addition amount of the above-mentioned flaky vanadium pentoxide is 10% of the mass of ammonium polyvanadate. The above-mentioned tail gas includes dust and waste gas. The dust includes sodium oxide, potassium oxide, ferric oxide and vanadium pentoxide, of which sodium oxide accounts for 15%, potassium oxide accounts for 15%, and vanadium pentoxide accounts for 15%. The waste gas includes nitrogen, carbon monoxide, carbon dioxide and ammonia. After the tail gas dries the ammonium metavanadate, the dust ash is collected by dust removal bags and can be directly returned to the leaching process in the sodium vanadium extraction process to extract and utilize the vanadium resources. The ammonia in the waste gas is absorbed by sulfuric acid to generate ammonium sulfate, which can be returned to the vanadium precipitation process in the sodium vanadium extraction process. The waste gas after sulfuric acid absorption is discharged through an exhaust pipe with an exhaust fan. A burner is set at the exhaust port to completely burn the carbon monoxide and then discharge the gas. S2. Graphite and ferric oxide are added to the mixture 1 obtained in step S1 to obtain a mixture 2, wherein the mass ratio of the mixture 1, graphite, and ferric oxide is 100:25:0.5. Water is then added in an amount of 16% of the mass of the mixture 2. The mixture is then mixed and milled for 3 hours and pressed into 30-40 mm elliptical spheres in a molding press at a static pressure of 5 MPa to obtain green balls having a repose angle of 16° and a moisture content of 5%. S3. The green balls obtained in step S2 are naturally aired to a moisture content of 1%, and then roasted in a direct-heated rotary kiln for 20 hours. The direct-heated rotary kiln has a length of 10 m and an internal diameter of 300 mm. The length ratio of the preheating section, the heating section, and the cooling section is 4:5:3. The maximum temperature of the heating section is 1500°C. During roasting, the inclination angle is 1.5°, the rotation speed is 0.3 m / min, and 99.999% nitrogen is always introduced into the kiln head. The nitrogen inlet flow rate is 80 m 3 / h, maintaining a slight positive pressure of 10Pa in the kiln, and after cooling to 65°C, a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt is obtained.

[0062] Example 3 A high-strength vanadium-nitrogen alloy based on vanadium ammonium salt, the preparation method of which comprises the following steps: S1. The moisture content of ammonium polyvanadate after plate and frame filtration is 45%, which is dried to 30% by compressed air. In a belt drying kiln, the tail gas of a direct-heated rotary kiln is dried to 5% moisture content. The tail gas temperature is 200°C. Then, flaky vanadium pentoxide is added and ground to a particle size of 180-200 mesh to obtain a mixture 1. The addition amount of the above-mentioned flaky vanadium pentoxide is 15% of the mass of ammonium polyvanadate. The above-mentioned tail gas includes dust and waste gas. The dust includes sodium oxide, potassium oxide, ferric oxide and vanadium pentoxide, of which sodium oxide accounts for 16%, potassium oxide accounts for 16%, and vanadium pentoxide accounts for 16%. The waste gas includes nitrogen, carbon monoxide, carbon dioxide and ammonia. After the tail gas dries the ammonium polyvanadate, the dust ash is collected by dust bag and can be directly returned to the leaching process in the sodium vanadium extraction process to extract and utilize the vanadium resources. The ammonia in the waste gas is absorbed by sulfuric acid to generate ammonium sulfate, which can be returned to the vanadium precipitation process in the sodium vanadium extraction process. The waste gas after sulfuric acid absorption is discharged through an exhaust pipe with an exhaust fan. A burner is set at the exhaust port to completely burn the carbon monoxide and then discharge the gas. S2. Graphite and ferric oxide are added to the mixture 1 obtained in step S1 to obtain a mixture 2, wherein the mass ratio of the mixture 1, graphite, and ferric oxide is 100:30:1. Water is then added in an amount of 22% by mass of the mixture 2. The mixture is then mixed and milled for 4 hours and pressed into 30-40 mm elliptical spheres in a molding press at a static pressure of 8 MPa to obtain green balls having a repose angle of 22° and a moisture content of 8%. S3. The green balls obtained in step S2 are naturally aired to a moisture content of 3%, and then roasted in a direct-heated rotary kiln for 25 hours. The direct-heated rotary kiln has a length of 10 m and an internal diameter of 300 mm. The length ratio of the preheating section, the heating section, and the cooling section is 5:5:3. The maximum temperature of the heating section is 1600°C. During roasting, the inclination angle is 3°, the rotation speed is 1 m / min, and 99.999% nitrogen is always introduced into the kiln head. The nitrogen inlet flow rate is 120 m 3 / h, maintaining a slight positive pressure of 20Pa in the kiln, and after cooling to 75°C, a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt is obtained.

[0063] Comparative Example 1 A method for producing a vanadium-nitrogen alloy comprises the following steps: preparing 3,000 kg of flake vanadium pentoxide (vanadium pentoxide) with a content greater than 98%, 855 kg of graphite, and 10 kg of iron oxide scale in a proportionate ratio; pulverizing the raw materials, mixing them, and pressing them into pellets. The pellets are intermittently added to the feed channel of a directly heated rotary kiln. When the material in the feed channel drops to the level detection device, an alarm is triggered, and manual refeed is required. The finely crushed material passes through the sieve holes in the sieve tube and falls into a temporary storage area for finely crushed material in the kiln tail box. As the rotary kiln rotates, the level of the pellets in the feed channel drops. The pellets then sequentially enter the kiln chamber feed inlet, preheating section, heating section, cooling section, kiln chamber discharge port, sieve tube feed inlet, sieve tube discharge port, pass through a baffle, and fall into a temporary storage area for large-particle material in the kiln tail box. Material is discharged from the kiln tail box every half an hour or an hour. The maximum temperature reached by the material in the heating section is 1500°C. The kiln chamber of a direct-heated rotary kiln is equipped with a refractory trough for stirring the material. The filling rate of the material balls in the heating section is approximately 45%. The voltage between the positive and negative terminals of the heating section is approximately 70V, the current is approximately 4500A, and the power is stable at 310-320kW. The equivalent inner diameter of the heating section chamber is 60cm (because the chamber contains the stirring trough, the chamber may be cylindrical or prismatic, resulting in a non-cylindrical shape, so the equivalent inner diameter is used to express it). The length of the heating section chamber is 6.6m.

[0064] Comparative Example 2 A method for producing a vanadium-nitrogen alloy comprises the following steps: mixing a vanadium oxide compound and a carbonaceous reducing agent, pressing and forming the mixture in a pelletizing machine, and then subjecting the mixture to a high-temperature reaction in a directly heated rotary kiln to obtain a vanadium-nitrogen alloy product, wherein the vanadium oxide is one or more of vanadium oxide of various valence states, ammonium metavanadate, ammonium polyvanadate or red vanadium.

[0065] Test Example 1 The element contents and densities of the high-strength vanadium-nitrogen alloys based on vanadium ammonium salts prepared in Examples 1-3 were tested, and the results are shown in Table 1.

[0066] Table 1 Element content and density

[0067] As shown in Table 1, the high-strength vanadium-nitrogen alloy based on vanadium ammonium salt prepared by the method provided by the present invention can reach a vanadium content of 76-78%, a nitrogen content of 16.5-19%, a carbon content of 3.2-4.2%, and a density of 3.8-4.4 g / cm 3 .

[0068] Test Example 2 The compressive strength and crushing rate (particle size less than 10 mm is considered crushing) of the green balls of the high-strength vanadium-nitrogen alloy based on vanadium ammonium salt prepared in Examples 1-3 were compared with those in Comparative Examples 1-2. The results are shown in Table 2.

[0069] Table 2 Performance comparison table

[0070] As can be seen from Table 2, the compressive strength of the high-strength vanadium-nitrogen alloy based on vanadium ammonium salt prepared by the method provided by the present invention is 1800-3000N, which is much higher than 580N of Comparative Example 1 and 40N of Comparative Example 2, and the crushing rate of the present invention does not exceed 5%, which is less than 15% of Comparative Example 1 and 35% of Comparative Example 2.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt, characterized in that: The following steps are involved: S1, vanadium ammonium salt is filtered through a plate and frame filter press, dried, and oven-dried, and then flaky vanadium pentoxide is added and ground to obtain mixture 1; S2, adding graphite and ferric oxide to the mixture 1 obtained in step S1 to obtain a mixture 2, and then adding water, mixing, grinding and pressing to obtain green balls; S3. The green balls obtained in step S2 are dried in the sun and then roasted. During the roasting, nitrogen is always introduced into the kiln head. After cooling, a vanadium-nitrogen alloy is obtained.

2. The method for preparing a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt according to claim 1, wherein: In step S1, the vanadium ammonium salt is ammonium metavanadate or ammonium polyvanadate.

3. The method for preparing a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt according to claim 1, wherein: In step S1, the product is dried in a belt drying kiln using direct heated rotary kiln tail gas to a moisture content of 1-5%.

4. The method for preparing a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt according to claim 1, wherein: In step S1, the amount of flaky vanadium pentoxide added is 10-30% of the mass of the vanadium ammonium salt.

5. The method for preparing a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt according to claim 1, wherein: In step S1, the powder is ground to a particle size of 180-200 mesh.

6. The method for preparing a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt according to claim 1, wherein: In step S2, the mass ratio of mixture 1, graphite and ferric oxide is 100:25-30:0.5-1.

7. The method for preparing a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt according to claim 1, wherein: In step S2, during pressing, the static pressure is 5-8 MPa.

8. The method for preparing a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt according to claim 1, wherein: In step S3, the calcination is carried out in a direct-heated rotary kiln, wherein the length ratio of the preheating section, the high-temperature section and the cooling section of the direct-heated rotary kiln is 4-5:5:

3.

9. The method for preparing a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt according to claim 1, wherein: In step S3, during calcination, the inclination angle is 1.5-3° and the rotation speed is 0.3-1 m / min.

10. A high-strength vanadium-nitrogen alloy based on vanadium ammonium salt prepared by the method for preparing a high-strength vanadium-nitrogen alloy based on vanadium ammonium salt according to any one of claims 1 to 9.

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