CN106048284A - Vanadium-nitrogen alloy and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of metallurgy, and in particular relates to a vanadium nitrogen alloy and a preparation method thereof. Aiming at the problems of low purity of the vanadium-nitrogen alloy prepared by using low-density vanadium trioxide in the prior art, the invention provides a method for preparing the vanadium-nitrogen alloy, which includes the steps of grinding, mixing and forming, and calcination of pellets. The method of the present invention adjusts the raw material composition and ratio, adds vanadium pentoxide and iron-based sintering aids, reduces the Gibbs free energy of the carbothermal reduction reaction through vanadium pentoxide, promotes the process of nitriding and deoxidation, and iron-based sintering aids The wetting angle of the liquid Fe ₃ C formed by the reaction of the graphite powder and the graphite powder is small, and the wetting effect is remarkable. The density of the vanadium-nitrogen alloy is increased through the liquid-phase intensified sintering. The method of the invention is simple to operate and has no waste. Significantly reduced production costs.

Description

A kind of vanadium nitrogen alloy and preparation method thereof

technical field

The invention belongs to the technical field of metallurgy, and in particular relates to a vanadium nitrogen alloy and a preparation method thereof.

Background technique

As an important alloying element, vanadium can play the role of precipitation strengthening and dispersion strengthening in steel, and is widely used in various steels, especially low-alloy high-strength steel. The density of vanadium-nitrogen alloy directly affects the recovery rate of vanadium in the steelmaking process. High-density vanadium-nitrogen alloy can prevent additives from floating on the surface of steel slag, promote contact with molten steel, and increase the recovery rate of vanadium in the steelmaking process. .

The density of vanadium trioxide produced by the prior art is relatively small, between 0.60 and 0.80 g·cm ^-3 , while the existing vanadium nitrogen alloy production process requires the density of vanadium trioxide to be no less than 1.00 g·cm ^-3 , there is a certain gap between the two. Using the low-density vanadium trioxide produced by the existing technology as the raw material, the finished vanadium-nitrogen alloy produced by the existing vanadium-nitrogen alloy technology has a density of only 2.92g·cm ^-3 , which is less than the minimum requirement of the national standard for vanadium-nitrogen alloys of 3.00g·cm ^-3 , if low-density vanadium trioxide is used for ferrovanadium smelting, according to the production statistics on site, the recovery rate of vanadium is about 95.00%, which is lower than 99.50% of vanadium-nitrogen alloy, and it is not conducive to improving the single structure of products currently on the market situation.

Research reports by Liu Xiansong, Liu Zhizhi and others: use powdered vanadium oxide or ammonium metavanadate, carbonaceous powder and binder, add a density increaser, mix uniformly, briquetting, molding, under nitrogen atmosphere Continuously feed into the externally heated rotary kiln, pre-fire to below 1000°C under the protection of nitrogen, and collect the pre-fired block products cooled to room temperature under the protection of nitrogen at the discharge port. Then push it into an improved soft magnetic nitrogen atmosphere pusher kiln, heat it to a temperature of 1000-1500 °C, the material undergoes carbonization and nitriding reactions, and obtains a vanadium-nitrogen alloy product after being released from the furnace. The prepared vanadium nitrogen alloy: V: 78-83%, N: 16-21%, C≤6%max, silicon, phosphorus and aluminum less than: 0.10%, and its apparent density is greater than 4.4g/cm ³ . The apparent density can be adjusted according to the needs of customers, up to 5.0g/cm ³ . The invention increases the apparent density of the vanadium-nitrogen alloy by adding a density increasing agent without improving the original production process conditions, so that the absorption rate of the vanadium-nitrogen alloy by molten steel is greater than 98%.

At present, there is no method for preparing a standard vanadium nitrogen alloy from a low-density vanadium trioxide raw material.

Contents of the invention

Aiming at the problem that the density of vanadium-nitrogen alloy prepared by using low-density vanadium trioxide in the prior art is too low to meet production needs, the purpose of the present invention is to provide a method for preparing high-density vanadium-nitrogen alloy by mixing vanadium oxide raw materials. The present invention does not need the pre-burning link, and directly performs the calcination operation, with fast reaction speed and high efficiency. At the same time, the raw material is a mixture of vanadium trioxide and vanadium pentoxide. Since vanadium pentoxide has a low melting point and high shrinkage performance, it can overcome The problem of low density of vanadium trioxide raw material, increase the density of the product, and prepare a vanadium nitrogen alloy that meets the standard.

The solution to the technical problem of the present invention is to provide a method for preparing a vanadium-nitrogen alloy, comprising the steps of:

a. Raw material preparation

Weigh raw materials according to parts by weight: 8-16 parts of vanadium pentoxide, 50-60 parts of vanadium trioxide, 20-30 parts of flake graphite, 0.8-1.6 parts of iron-based sintering aid, and 0.8-2 parts of liquid phase inducer , crushed;

b. Mixed material compression molding

Mix the raw materials in step a for 25 to 40 minutes, add 8 to 12 parts of water, mix for another 25 to 40 minutes, and press to form pellets;

c. Ball calcination

Reacting the pellets obtained in step b in a pusher kiln protected by a nitrogen atmosphere for 6-8 hours at a reaction temperature of 400-1520°C, taking them out of the furnace and cooling to obtain a vanadium-nitrogen alloy;

The iron-based sintering aid described in step a is at least one of reduced iron powder, red iron oxide, ferric oxide or ferrous oxide; the liquid phase inducer is vanadium carbide, vanadium nitride or carbon at least one of vanadium nitride.

Wherein, in the above method for preparing vanadium-nitrogen alloy, the density of vanadium trioxide in step a is 0.60˜0.80 g·cm ⁻³ .

Preferably, the source of the low-density vanadium trioxide is: the clinker after vanadium slag is calcified and roasted is leached with sulfuric acid to obtain a vanadium-containing acid immersion solution, and ammonium polyvanadate is prepared by acidic ammonium salt vanadium precipitation, and then ammonium polyvanadate is obtained by Reduction to get vanadium trioxide.

Wherein, in the above-mentioned preparation method of vanadium-nitrogen alloy, the vanadium pentoxide described in step a is vanadium pentoxide with a total vanadium content of 52-56 wt%, and the vanadium trioxide is vanadium trioxide with a total vanadium content of 63-68 wt%. Vanadium oxide.

Wherein, in the above method for preparing vanadium-nitrogen alloy, the pulverized particle size in step a is ≤140 mesh.

Wherein, in the above method for preparing vanadium-nitrogen alloy, the iron-based sintering aid in step a is a mixture of ferric oxide and metallic iron in a weight ratio of 3-5:5-7.

Preferably, in the above method for preparing vanadium-nitrogen alloy, the iron-based sintering aid described in step a is 1.0-1.4 parts, preferably 1.2 parts.

Preferably, in the above method for preparing vanadium-nitrogen alloy, the amount of vanadium pentoxide added in step a is 10-15 parts, preferably 12 parts.

Wherein, in the above-mentioned preparation method of vanadium-nitrogen alloy, the amount of water added in step b is 9.5-10.5 parts, preferably 10 parts.

Wherein, in the preparation method of the above-mentioned vanadium-nitrogen alloy, the molding pressure in step b is 30-50 kN during pressing, and the pressure-holding time is 5-8 minutes.

Wherein, in the preparation method of the above-mentioned vanadium-nitrogen alloy, the weight of the pellets in step b is 50-60 g.

Wherein, in the preparation method of the above-mentioned vanadium-nitrogen alloy, in step c, the nitrogen atmosphere protects the nitrogen and oxygen content in the pusher kiln at 5-8ppm.

The present invention also provides a vanadium nitrogen alloy prepared by the above preparation method.

The beneficial effects of the present invention are: when using low-density vanadium trioxide to prepare vanadium-nitrogen alloy, it is easy to cause the phenomenon that the density of the vanadium-nitrogen alloy is too low. A certain amount of vanadium pentoxide is added to vanadium trioxide, and a certain amount of graphite, iron-based sintering aid and liquid phase inducer are added at the same time. Vanadium pentoxide is beneficial to reduce the Gibbs free reaction of carbothermal reduction reaction. It can promote the process of nitriding and deoxidation. The liquid Fe ₃ C produced by the reaction of iron-based sintering aids and graphite powder has a small wetting angle in contact with carbides, and the wetting effect is significant. The sintering is strengthened by the liquid phase, that is, a sufficiently high sintering At high temperature, the additive or additive product melts to form a liquid phase and fills the holes. With the flow of the liquid phase, the particles slide, rotate, and rearrange, the bridges of the particles are wetted, the particles are placed in a separated state, and the separated particles slide further. , driven by the capillary force of the liquid phase, the sliding particles form close packing, thereby increasing the degree of densification, increasing the density of the final product vanadium-nitrogen alloy, and realizing the conversion of low-density vanadium trioxide to high-density vanadium-nitrogen alloy , effectively saving the production cost, and providing a new method for high-density vanadium-nitrogen alloys. The preparation method of the present invention has a simple process and does not produce any industrial waste; it reduces the production investment cost: no grinding and pelletizing process is added, the process and equipment are further simplified, and the investment cost is significantly reduced; low-density vanadium trioxide raw material is realized The high-value utilization has created significant economic benefits for enterprises.

detailed description

The invention provides a kind of preparation method of vanadium nitrogen alloy, comprises the following steps:

a. Abrasives: Add 8-16 parts of vanadium pentoxide, 50-60 parts of vanadium trioxide, 20-30 parts of flake graphite, 0.8-1.6 parts of iron-based sintering aid, and 0.8-2 parts of liquid phase inducer to -140 mesh or less;

b. Mixing and forming: dry mix all raw materials for 25-40 minutes first, then add 8 to 12 parts of water, and perform wet mixing for 25-40 minutes. After mixing, press molding to obtain molding balls;

c. React the pellets obtained in step b in a pusher kiln protected by a nitrogen atmosphere for 6-8 hours, take them out of the furnace at 400-1520°C, and cool to 200-250°C to obtain a vanadium-nitrogen alloy;

The liquid phase inducer in step a is at least one of vanadium carbide, vanadium nitride or vanadium carbonitride, and the iron-based sintering aid is reduced iron powder, red iron oxide, ferric oxide or ferrous oxide at least one of iron.

Wherein, in the above-mentioned preparation method of vanadium-nitrogen alloy, the vanadium pentoxide described in step a is preferably vanadium pentoxide with a total vanadium content of 52-56 wt%, and the vanadium trioxide is preferably vanadium trioxide with a total vanadium content of 63-68 wt%. vanadium trioxide, the density of vanadium trioxide is 0.60～0.80g·cm ^-3 , it is the vanadium-containing acid immersion solution obtained from the clinker after calcification and roasting of vanadium slag and sulfuric acid leaching, and is prepared by acidic ammonium salt vanadium precipitation method Ammonium vanadate is obtained, and after reduction, vanadium trioxide is obtained.

Wherein, in the above-mentioned preparation method of vanadium nitrogen alloy, the iron-based sintering aid described in step a is at least one of reduced iron powder, iron oxide red, ferric oxide or ferrous oxide; preferably ferric oxide A mixture with metallic iron, more preferably, the iron-based sintering aid is a mixture of ferric oxide and metallic iron in a weight ratio of 3-5:5-7.

In order to increase the density of the product vanadium-nitrogen alloy, a certain proportion of vanadium pentoxide and iron-based sintering aids are added in step a. The addition of vanadium pentoxide is beneficial to reduce the Gibbs free energy of carbothermal reduction reaction and promote nitriding Deoxidation process; the liquid Fe ₃ C produced by the reaction of iron-based sintering aids and graphite powder has a small wetting angle in contact with carbides, and the wetting effect is significant. Through liquid phase strengthening sintering, the product density is increased. The iron-based sintering aid is preferably a mixture of ferric oxide and metallic iron, and the mass fraction in percentage is preferably 0.8-1.6 parts, more preferably 1.0-1.4 parts, most preferably 1.2 parts; The mass fraction is preferably 8-16 parts, more preferably 10-15 parts, most preferably 12 parts.

Preferably, in order to prepare the pellets with a higher density, the particle size of the raw materials should be strictly controlled. If the particle size is too large, it will affect the process of heat and mass transfer during the reaction; if the particle size is too fine, it will increase the grinding cost, and the too fine particle size is not conducive to the molding of the raw materials. The invention After experimenting, it was found that when all the raw materials were crushed to below -140 mesh, the vanadium-nitrogen alloy obtained had the highest density and the best effect.

In order to prepare pellets with higher density and better quality, in the preparation method of the above-mentioned vanadium-nitrogen alloy, the molding pressure in step b is 30-50kN during pressing, the holding time is 5-8 minutes, and the quality of the pellets is controlled to be 50 ~60g.

In order to press the ball into shape, a certain amount of water is added as a binder in the present invention, and the amount of water added is preferably 9.5-10.5 parts, most preferably 10 parts.

After pressing the pellets, in order to prevent the oxidation of the vanadium-nitrogen alloy, the obtained pellets are put into a nitrogen atmosphere to react, and the nitrogen oxygen content in the nitrogen atmosphere double-channel pusher kiln is controlled at 5-8ppm, and the reaction temperature is 400-1520 °C, take the platform temperature rise curve from 400 °C to 950 °C linearly;

The pusher kiln is a commonly used equipment in the method of preparing vanadium-nitrogen alloys, and its parameters and process settings have been basically mature. In the method for preparing vanadium-nitrogen alloys by mixing vanadium oxide raw materials in the present invention, the vanadium nitrogen produced by the existing pusher kiln is not used. The large-scale modification of the alloy process is only based on the fact that low-density vanadium trioxide will greatly affect the density of the alloy. A certain proportion of low-melting vanadium pentoxide is added to the low-density vanadium trioxide raw material. The phase strengthening effect and strong volume shrinkage effect increase the product density; at the same time, the addition of iron-based sintering additives further strengthens the effect of liquid phase strengthening and promotes the reaction process.

The present invention also provides a vanadium nitrogen alloy prepared by the above preparation method. After being prepared by the preparation method of the present invention, the chemical composition of the final product (ie vanadium nitrogen alloy) meets the requirements of GB/T 20567-2006, and the density is 3.12-3.48g·cm ^-3 .

The specific implementation of the present invention will be further described below in conjunction with the examples, and the present invention is not limited to the scope of the examples.

The quality of flake graphite used in the examples complies with the relevant provisions of the national standard GBT3518-2008, the fixed carbon content is ≥ 98%, the volatile matter content is ≤ 1%, and the liquid phase inducer and iron-based sintering aid are common industrial products; Example The roller hydraulic press model used in the paper is YYQD560×216, the main motor power is 22kw, the maximum thrust of the pressure roller is 83t, and the pressure roller specification is 560×216; the push plate kiln used in the embodiment is a 36mTBY kiln, and the push plate push speed is 17min/block, The nitrogen pressure is 0.02MPa, and the nitrogen flow rate is 1.440km3/h.

Example 1 Preparation of vanadium nitrogen alloy with the technical solution of the present invention

a. Abrasives: 12 parts of vanadium pentoxide (V ₂ O ₅ ), 52 parts of vanadium trioxide (V ₂ O ₃ ), 24 parts of flake graphite, 1.2 parts of iron-based sintering aid (0.6 parts of reduced iron powder, 0.6 part of ferric oxide) and 0.8 part of liquid phase inducer VN16 alloy abrasive to below -140 mesh;

b. Mixing and molding: import all the materials in step a into the mixer for 30 minutes of dry mixing operation, then add 10 parts of tap water, and perform 30 minutes of wet mixing operation on the wet mixing equipment. Ball making operation to make balls with a certain shape and strength, and the quality of each ball is controlled at about 50g;

c. Calcination of pellets: feed pellets into a double-channel pusher kiln with nitrogen atmosphere, react with nitrogen at 400°C to 1520°C, and cool to obtain a vanadium-nitrogen alloy.

Wherein, steps a to b are carried out at normal temperature and pressure, and step c is carried out at normal pressure and very temperature.

According to the measurement, the chemical composition of the vanadium nitrogen alloy obtained in this example is: TV: 78.48%, N: 14.72%, C: 4.68%, P: 0.024%, S: 0.036%, and the bulk density of the alloy is 3.38g·cm ^-3 .

Example 2 Preparation of vanadium nitrogen alloy with the technical solution of the present invention

a. Abrasives: 8 parts of vanadium pentoxide (V ₂ O ₅ ), 56 parts of vanadium trioxide (V ₂ O ₃ ), 23.4 parts of flake graphite, 1.0 parts of iron-based sintering aid (0.5 parts of reduced iron powder, 0.5 parts of ferric oxide) and 1.2 parts of liquid phase inducer VN16 alloy abrasive to -140 mesh or less;

b. Mixing and molding: import all the materials in step a into the mixer for 30 minutes of dry mixing operation, then add 10 parts of tap water, and perform 30 minutes of wet mixing operation on the wet mixing equipment. Ball making operation to make balls with a certain shape and strength, and the quality of each ball is controlled at about 50g;

c. Calcination of pellets: feed pellets into a double-channel pusher kiln with nitrogen atmosphere, react with nitrogen at 400°C to 1520°C, and cool to obtain a vanadium-nitrogen alloy.

Wherein, steps a to b are carried out at normal temperature and pressure, and step c is carried out at normal pressure and very temperature.

According to the measurement, the chemical composition of the vanadium nitrogen alloy obtained in this example is: TV: 77.91%, N: 15.30%, C: 4.58%, P: 0.017%, S: 0.012%, and the bulk density of the alloy is 3.26g·cm ^-3 .

Example 3 Preparation of vanadium nitrogen alloy with the technical solution of the present invention

a. Abrasives: 10 parts of vanadium pentoxide (V ₂ O ₅ ), 56 parts of vanadium trioxide (V ₂ O ₃ ), 24.2 parts of flake graphite, 0.9 parts of iron-based sintering aid (0.45 parts of reduced iron powder, 0.45 parts of ferric oxide) and 0.9 parts of liquid phase inducer VN16 alloy abrasive to below -140 mesh;

b. Mixing and forming: import all the materials in step a into the mixer for 30 minutes of dry mixing operation, then add 8 parts of tap water, and perform 30 minutes of wet mixing operation on the wet mixing equipment. Ball making operation to make balls with a certain shape and strength, and the quality of each ball is controlled at about 50g;

c. Calcination of pellets: feed pellets into a double-channel pusher kiln with nitrogen atmosphere, react with nitrogen at 400°C to 1520°C, and cool to obtain a vanadium-nitrogen alloy.

Wherein, steps a to b are carried out at normal temperature and pressure, and step c is carried out at normal pressure and very temperature.

According to measurements, the chemical composition of the vanadium-nitrogen alloy obtained in this example is: TV: 77.40%, N: 15.78%, C: 4.23%, P: 0.032%, S: 0.021%, and the bulk density of the alloy is 3.43g·cm ^-3 .

Comparative example 4 Preparation of vanadium nitrogen alloy without adding vanadium pentoxide

Except not adding vanadium pentoxide, all the other steps are with embodiment 1, and the vanadium-nitrogen alloy assay result that prepares is as follows:

TV: 78.38%, N: 14.78%, C: 4.76%, P: 0.026%, S: 0.018%, and the bulk density of the alloy is 2.98g·cm ^-3 .

Comparative Example 5 Preparation of vanadium nitrogen alloy without adding iron-based sintering aids

Except not adding iron-based sintering aid, all the other steps are the same as in Example 1, and the measured results of the vanadium-nitrogen alloy prepared are as follows:

TV: 79.02%, N: 12.78%, C: 5.73%, P: 0.041%, S: 0.038%, and the bulk density of the alloy is 2.83g·cm ^-3 .

It can be seen from the test results that the preparation of vanadium-nitrogen alloy by using the technical solution of the present invention has a simple process, and by adding vanadium pentoxide and iron-based sintering aids, the raw materials cooperate with each other to increase the density of the product vanadium-nitrogen alloy. The technical problem that the low-density vanadium trioxide cannot be prepared to obtain the high-density vanadium-nitrogen alloy is solved, and the production cost is greatly reduced, and the economic benefit is improved. The added raw materials such as vanadium pentoxide and iron-based sintering aids have an intricate relationship with each other. The technical solution of the present invention works as an overall technical solution. The invention discloses a method for preparing a high-density vanadium-nitrogen alloy from vanadium trioxide.

Claims (10)

1. a preparation method of vanadium nitrogen alloy, is characterized in that, comprises the steps: a. Raw material preparation Weigh raw materials according to parts by weight: 8-16 parts of vanadium pentoxide, 50-60 parts of vanadium trioxide, 20-30 parts of flake graphite, 0.8-1.6 parts of iron-based sintering aid, and 0.8-2 parts of liquid phase inducer , crushed; b. Mixed material compression molding Mix the raw materials in step a for 25 to 40 minutes, add 8 to 12 parts of water, mix for another 25 to 40 minutes, and press to form pellets; c. Ball calcination Reacting the pellets obtained in step b in a pusher kiln protected by a nitrogen atmosphere for 6-8 hours at a reaction temperature of 400-1520°C, taking them out of the furnace and cooling to obtain a vanadium-nitrogen alloy; The iron-based sintering aid described in step a is at least one of reduced iron powder, red iron oxide, ferric oxide or ferrous oxide; the liquid phase inducer is vanadium carbide, vanadium nitride or carbon at least one of vanadium nitride. 2. The method for preparing a vanadium-nitrogen alloy according to claim 1, characterized in that the density of vanadium trioxide in step a is 0.60-0.80 g·cm ^-3 . 3. according to the preparation method of claim 1 or 2 described vanadium-nitrogen alloys, it is characterized in that: the vanadium pentoxide described in the step a is the vanadium pentoxide of 52～56wt% total vanadium content, vanadium trioxide It is vanadium trioxide with a total vanadium content of 63-68 wt%. 4. The method for preparing vanadium-nitrogen alloy according to any one of claims 1-3, characterized in that: the pulverized particle size in step a is ≤140 mesh. 5. The method for preparing vanadium-nitrogen alloy according to any one of claims 1-4, characterized in that: in step a, the iron-based sintering aid is ferric oxide and metal with a weight ratio of 3-5:5-7 Iron mixture. 6. The method for preparing a vanadium-nitrogen alloy according to any one of claims 1-5, characterized in that the iron-based sintering aid described in step a is 1.0-1.4 parts. 7. The method for preparing a vanadium-nitrogen alloy according to any one of claims 1-6, characterized in that the amount of water added in step b is 9.5-10.5 parts. 8. The method for preparing a vanadium-nitrogen alloy according to any one of claims 1-7, characterized in that: the molding pressure in step b is 30-50 kN during pressing, and the holding time is 5-8 minutes. 9. The method for preparing a vanadium-nitrogen alloy according to any one of claims 1-8, characterized in that: in step c, the nitrogen atmosphere protects the pusher kiln with a nitrogen and oxygen content of 5-8 ppm. 10. A vanadium-nitrogen alloy prepared by the preparation method according to any one of claims 1-9.