CN114381626A - Efficient vanadium-nitrogen alloy production process - Google Patents
Efficient vanadium-nitrogen alloy production process Download PDFInfo
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Abstract
The invention discloses a high-efficiency vanadium-nitrogen alloy production process, which comprises the steps of mixing a carbon agent powder and a molten V2O5The invention has the advantages of high production efficiency, good product quality, high and stable vanadium and nitrogen contents, low production cost, low energy consumption and material consumption and small equipment occupation area.
Description
Technical Field
The invention relates to the field of additive production in ferrous metallurgy, in particular to a vanadium-nitrogen alloy production technology.
Background
In the existing industrial production of vanadium-nitrogen alloy, vanadium oxide is used as a raw material, and V is mainly used2O5The vanadium-nitrogen alloy is obtained by carbothermal reduction nitridation as a raw material, and the main flow process for producing the vanadium-nitrogen alloy is shown in an attached figure 2.
The carbothermic reduction reaction and the nitridation reaction occur in a vertical kiln or a pushed slab kiln, and the carbothermic reduction reaction formula is shown as follows.
V2O5( s) + 6C( s) = 2VC( s) + CO2( g) ↑+ 3CO( g) ↑
The nitridation reaction formula is as follows.
2VC( s) + N2( g) = 2VN( s) + 2C
The total reaction formula for generating the vanadium-nitrogen alloy is as follows.
V2O5( s) + 4C( s) + N2( g) = 2VN( s) + CO2( g) ↑+ 3CO( g) ↑
According to the phase analysis of the product, the molecular formula of the actual vanadium-nitrogen alloy product is VNxCy (x is 0.5-0.8; y is 0.1-0.5), taking x as 0.75 and y as 0.15 as an example,
the reaction formula in the actual production is as follows.
V2O5( s) + 4.3C( s) + 0.75N2( g) = 2VN0.75C0.15( s) + CO2( g)↑+ 3CO( g)↑
Calculated and obtained V per ton2O5Starting material (containing V)2O598%) carbon consumption is 278Kg, the loss of the procedures of mixing, ball pressing, drying and the like is 1.05 coefficient, the total consumption is 292Kg, the total consumption accords with the actual carbon consumption of 290-300 Kg, and the generation amount of CO is large, because CO generated in the carbon thermal reduction is diffused from the pellets and accumulated in the upper cavity of the pushed slab kiln, most of the CO is directly discharged from the top exhaust port and cannot continuously participate in the reaction, if the CO can continuously participate in the reaction, the reaction is mainly carried out in the following reaction formula.
7V2O5( s) + 22.1C( s)+5.25N2( g) = 14VN0.75C0.15( s) +15CO2( g)↑+5CO( g)↑
Calculated and obtained V per ton2O5Starting material (containing V)2O598 percent) consumes 204Kg of carbon, and the total carbon consumption is 214Kg by taking the loss coefficient of 1.05, so that the carbon consumption is greatly reduced.
The carbothermic nitridation process of vanadium oxide is a typical gas-solid reaction involving the in-diffusion of carbon and nitrogen into the interstitial spaces of the matrix phase and the out-diffusion of oxygen from the matrix phase.
From the reaction kinetics, the carbothermic reduction is a pressurization process with enlarged volume, so the pressure reduction is favorable for the reaction; meanwhile, nitridation is a pressure reduction process with reduced volume, so that pressurization is beneficial to reaction, and the conventional production equipment, namely a vertical kiln or a pushed slab kiln, cannot simultaneously perform pressurization and pressure reduction.
From the top, the reaction rate is slow, the production cycle is long, from the entering of the pressed green pellets to the discharging of the produced vanadium-nitrogen alloy pellets, generally 45-55 hours are needed, the pellets are expanded and then contracted, the apparent density of finished pellets is more than 3g/cm (required by the national standard VN 16), and the pellets are softened, collapsed and contracted only by keeping a long retention time at a high temperature, which often occurs in production practice, and in order to improve the yield and accelerate the feeding and discharging speed, the phenomenon that the content of each component of the vanadium-nitrogen alloy pellets reaches the national standard VN16 and the apparent density cannot be achieved is often caused. After the material balls softened and contracted at high temperature are cooled and discharged, the material balls are often bonded into large vanadium-nitrogen alloy balls, large external force is needed to be applied to separate the material balls to reach the required granularity, and mechanical separation increases powder, so that the manual labor intensity is high.
The medium-frequency induction heating vertical kiln is used as a vanadium-nitrogen alloy production device and is limited by the working principle of equipment, the yield of a single set of device is not high, the automation degree is poor, the production efficiency is low, the energy consumption is high, the large-scale production is not competitive, the existing production device is mainly a pushed slab kiln, the yield of the single set of device can reach 6 tons every day, the product quality is stable, and the automation degree is relatively high. There are major problems.
(1) The energy consumption and material consumption are high, the kiln length is more than or equal to 40m, the high-temperature section of 1200-1550 ℃ in the kiln occupies two thirds of the length, the kiln body is large in size, the heat dissipation area is large, and the heat loss is large; the reaction is slow, the sintering time is long, and the production efficiency is low; the power consumption per ton of the product is more than 4000 kWh; high unit consumption of carbonaceous reducing agent, large amount of CO generated in the carbothermic reduction process, combustion emission adopted, no utilization, and V per ton2O5290 Kg-300 Kg of graphite powder is consumed as raw material, and only a small amount of amorphous graphite powder with fast reaction activity can be blended and used, otherwise, the product is cracked and cannot be formed. For V of the same batch2O5The carbon blending quantities of different kilns in the production workshops of the raw materials are different greatly, the difference can reach 20 Kg-30 Kg, and even the carbon blending quantity of the same kiln after overhaul is changed under the same production control condition.
(2) The start-up and shutdown of the furnace consumes long time, and equipment devices are easy to damage. The debugging of the furnace opening and the furnace drying needs 15 days, the temperature reduction of the furnace closing needs 7 days, and the furnace opening and the furnace stopping are inconvenient. The furnace body is maintained in a heat preservation shutdown mode, the time for building and baking the furnace is at least 25 days, the maintenance cost is high every year, and the shutdown phenomenon caused by the arch bars is generated occasionally. The graphite charging bucket has serious sliding abrasion in the kiln body when reacting at high temperature, and the silicon molybdenum rod and the silicon carbon rod of the heating device have short service life when being in high-temperature environment for a long time.
(3) The product quality is to be improved continuously, the national standard VN16 and below is generally produced, the main content vanadium and nitrogen are not accurately controlled, the fluctuation is large, for some customers, even if the product is higher than the national standard lower limit, the product does not exceed the contract terms of corresponding multi-reduced amount, for some customers, the product is higher than the national standard lower limit and is not cost-effective, some manufacturers blend and pack the product with high vanadium content and the batch product with the vanadium content not reaching the national standard, the conversion can reach the standard, the product is actually unqualified, and during delivery and sampling, the detection is unqualified, and the risk of deduction or return is caused. Secondly, the carbon and oxygen contents are higher, the carbon content is generally more than 3.5 percent, and the oxygen content is more than 1.5 percent; the adjustment range of the main content of vanadium and nitrogen is small. The density can not be increased by adding more iron powder, and 4Kg to 8Kg of iron powder is generally added to each ton of vanadium raw material.
Disclosure of Invention
Aiming at the defects of the technology, the invention provides an efficient vanadium-nitrogen alloy production process, which comprises the steps of preparing a carbon agent powder and a molten state V2O5Mixing and reducing by nitrogen atomization, then carrying out carbothermic reduction and nitridation to obtain vanadium-nitrogen alloy powder, cooling, adding iron powder, mixing, pressing, molding, and sintering and nitridation to obtain a vanadium-nitrogen alloy finished product.
The specific technical scheme of the invention is as follows: a high-efficiency vanadium-nitrogen alloy production process is characterized by comprising the following steps:
firstly, pyrolyzing and melting vanadium compounds: heating vanadium compound in a calcining furnace to 500-650 ℃ to obtain vanadium oxide and ammonia gas, then putting the vanadium oxide into a melting furnace, heating the vanadium oxide to 690-750 ℃ in an oxygen-enriched manner to obtain molten V2O5And (4) liquid.
Secondly, atomizing and mixing: the preheated nitrogen gas mixture is used to pneumatically convey the carbon powder without oxygen to the atomizer to make molten V2O5Liquid is sucked into the atomizer and atomized and mixed into fine liquid-solid mixture at the outlet of the atomizerRapidly carrying out carbothermic reduction reaction and partial nitridation reaction in an atomization chamber to generate powder, controlling the particle size of the powder to be 100-200 um, and feeding the reaction powder and reaction gas into a fluidized bed nitriding furnace; reacting gas as a secondary gas source to participate in the reaction of the fluidized bed, controlling the temperature of an atomization chamber to be 800-1000 ℃, and controlling the pressure of an atomizer to be 0.5-2 MPa; v into the atomizer2O5And the carbon agent powder in a mass ratio of 1: 0.2 to 0.3, and keeping the molten state V2O5The liquid level is at a certain height to prevent air from entering, and nitrogen is used for replacing the gas in the atomizing chamber and the fluidized bed nitriding furnace before atomization.
Boiling carbonization and nitridation: the reaction powder entering the boiling nitriding furnace from the atomizing chamber forms a material layer in the furnace, the material layer state is controlled between a fixed bed and a fluidized bed for conversion, nitrogen is introduced from a blast cap at the bottom of the boiling nitriding furnace, the nitrogen amount is gradually increased, when the material layer starts to fluidize, the nitrogen amount is immediately reduced until the minimum gas velocity amount is reached, then the nitrogen amount is slowly increased until the material layer starts to fluidize again, and when the material layer is periodically and repeatedly fluidized, the material layer is fixed and solidified; the gas and the solid are fully contacted, so that the incomplete carbonization reaction and the nitridation reaction are further accelerated; controlling the temperature of the lower section of the fluidized nitriding furnace to be 1000-1200 ℃; the height of the material layer of the fluidized bed is kept between 0.5m and 5m, and the gas speed of the fluidized nitriding furnace is controlled between 0.2 m/s and 6 m/s; a small amount of fine powder enters a separator from an outlet of the upper section of the boiling nitriding furnace for recovery, and is atomized again by an atomizer, and the temperature of the upper section of the boiling nitriding furnace is adjusted to 500-600 ℃ by a cooling coil and a water cooling jacket.
Fourthly, detecting and discharging; the reaction retention time is kept by controlling the downward moving speed of the material layer of the fluidized bed furnace, the retention time is controlled to be 1-3 hours, sampling ports are arranged at the lower section and the middle section of the fluidized bed nitriding furnace, the powder component content is sampled and analyzed, and the V entering an atomizing chamber and the fluidized bed nitriding furnace is adjusted according to the analysis result2O5Ratio to carbon powder and V2O5And N2The proportion and the material layer residence time, and when the product meets the quality control requirement, the product is cooled to below 200 ℃ to discharge vanadium-nitrogen alloy powder.
Fifthly, mixing materials and pressing for forming: analyzing the components of the vanadium-nitrogen alloy powder, determining the amount of added iron powder and a binder, and controlling the mass ratio of the vanadium-nitrogen alloy powder to the iron powder to be 1: 0.02-0.04, adding the binder after uniformly mixing, mixing and stirring uniformly, and pressing the mixture into balls by a forging press or a roller press, wherein the granularity of each finished product is 30-40 mm.
And sixthly, sintering, namely heating the vanadium-nitrogen alloy ball in nitrogen atmosphere at the temperature of 1200-1400 ℃, further performing nitridation sintering, reacting for 1-5 hours, and cooling to below 200 ℃ to obtain a vanadium-nitrogen alloy finished product.
Further, the amount of pure iron powder or ferric oxide powder and carbon agent powder or vanadium oxide powder are accurately calculated according to the content of vanadium, nitrogen, carbon and oxygen in the cooled and discharged vanadium-nitrogen alloy powder, the mixed material is pressed and formed and then enters a pressure-increasing nitriding furnace for further pressure nitriding, the pressure in the furnace is 0.2MPa, the temperature is 1200-1400 ℃, the nitrogen content is increased within 1-8 hours of reaction time, and the vanadium-nitrogen alloy finished product with high nitrogen content is obtained and meets the requirement of the national standard VN19 mark.
Further, adding pure iron powder into the vanadium-nitrogen alloy powder, uniformly mixing, heating to 1200-1500 ℃ in a nitrogen atmosphere sintering furnace, reacting for 1-3 hours, cooling to obtain a sintered block, grinding, adding a binder, pressing for molding, and drying at 200 ℃ to obtain a vanadium-nitrogen alloy finished product with high apparent density.
Further, when the vanadium compound is ammonium metavanadate or ammonium polyvanadate, oxygen-isolating pyrolysis is adopted, decomposed ammonia gas is purified and then is used as supplement of pure nitrogen gas, and then vanadium oxide is further subjected to oxygen-enriched oxidation and heated into a molten state V2O5When the vanadium compound is V2O5Directly heating and melting.
Further, the molten state V2O5Before atomization, 0.5-2% of reduced iron powder or iron oxide powder is added into the molten liquid and uniformly stirred, the particle size of the atomized and mixed powder is further controlled, the reaction contact area is increased, and the reaction speed is accelerated, wherein the particle size of the reduced iron powder or the iron oxide powder is 75-120 um.
Further, the carbon agent powder is at least one of carbon black, low-sulfur petroleum coke powder, charcoal powder, activated carbon powder, graphite electrode powder and graphite powder, the carbon content is more than 98.5%, the granularity is 300-500 meshes, the oxygen removal of the carbon agent powder adopts vacuumizing and then nitrogen filling for replacement or replacement with produced exhaust gas for oxygen removal, and the binder is sodium water glass or potassium water glass or instant powder sodium silicate or dextrin water solution.
Further, the boiling nitriding furnace material layer reaches 0.5-5 m, and the molten state V is stopped2O5And the carbon powder enters an atomizer, the gas amount of the nitrogen gas mixture is reduced, the separator and the dust remover are kept to recover the powder and enter an atomizing chamber, samples are taken from sampling ports at the lower section and the middle section of the boiling nitriding furnace, the component content of the powder is analyzed, when the carbon content is less than 3 percent and the oxygen content is more than 4 percent, the carbon powder is supplemented while pure nitrogen is fed from the bottom of the boiling nitriding furnace, the periodic fluidization reaction of a material layer is kept, and after the sampling is qualified, vanadium-nitrogen alloy powder is discharged; the raw materials enter the atomizer again for atomization and mixing.
Furthermore, the nitrogen is preheated before entering the blast cap at the bottom of the fluidized bed nitriding furnace, the separator is provided with a water-cooling jacket and a cooling coil, and the temperature of outlet gas of the separator is controlled to be 200-300 ℃.
Further, the nitrogen gas mixture is pure nitrogen or the mixture of pure nitrogen and part of tail gas at the outlet of the dust remover after being cooled and pressurized, and CO of the mixture2And N2In a molar ratio of 1: 1-3; v into the atomizer2O5And N2In a molar ratio of 1: 1-8; the pure nitrogen gas refers to pure nitrogen gas with the nitrogen content of 99.999 percent.
The invention has the beneficial effects that:
1. the product has good quality, high vanadium and nitrogen content and stability, can produce all brands of products in vanadium-nitrogen alloy (GB/T20567-2020), and the amount of the iron powder added in each ton of vanadium-nitrogen alloy powder is 10 Kg-30 Kg according to the product requirements; the iron powder can further accurately control the contents of vanadium and nitrogen. The impurity content in the finished product is controlled to be lower, the carbon content is controlled to be below 3 percent, and the existing product is usually 3.5 to 5 percent; the oxygen content is controlled below 0.8 percent, while the oxygen content of the existing product is more than 1.5 percent.
2. The production efficiency is high. Boiling reaction, high heat and mass transfer rate, and high adsorption and separation speed of phase-layer interface,Solid-phase reaction and gas-solid-phase reaction. The total production time of a batch of products can be controlled within 24 hours, and the production scale enlargement of a single set of device is easy to realize; compared with the fixed bed reaction of pressing balls after the materials are pulverized and mixed in the prior art, the efficiency is improved by more than 5 times according to measurement and calculation. Also extend and integrate the production process to the direction of raw materials, and melt state V2O5Without cooling to form vanadium flakes and then milling the same to form a molten V2O5Direct atomization, utilization of heat and no grinding process.
3. The production cost is low, the energy consumption and the material consumption are low, the mixture is mixed by an atomizer and reacts firstly, the mixture stays in an atomizing chamber to react, then the mixture reacts in a fluidized bed nitriding furnace again, the three-stage reaction is firstly reduced, carbonized and then nitrided, and the reaction can be carried out:
7V2O5( s) + 34C( s) = 14VC( s) + 15CO2( g)↑+5CO( g)↑
3V2O5( s) + 16C( s) = 6VC( s) + 5CO2( g)↑+5CO( g)↑
2VC( s) + N2( g) = 2VN( s) + 2C
while carbonizing and nitriding, also has the reaction formula:
V2O5( s) + 2C( s) = 2VO s) + CO2( g)↑+CO( g)↑
VO( s) + 3CO( g) = VC( s) +2CO2 ( g)↑
VC( s) + VO( s) + N2( g) = 2VN( s) +CO( g)↑
vanadium oxide from high-valence V2O5(Density 3.4 g/cm) Abort) preliminary reduction to produce V2O3(Density 4.8 g/cm) and VO2(Density 4.6 g/cm) and then carbonizing to VO (Density 5.7 g/cm) and VC (Density 5.6 g/cm) and nitriding to VN (Density 5.6 g/cm) distributed from top to bottom and at the top V in the boiling nitriding furnace layer2O3，VO2VO, VC and VN are arranged at the lower part, gas generated by reaction, nitrogen and carbon powder are in countercurrent contact with the material layer from bottom to top, and the lower part is the same as the upper part V2O3，VO2VO, VC and VN are generated through reaction; VO which does not complete reaction, and nitrogen which is continuously fed in from the bottom in the sinking process of VCPerforming nitridation reaction to generate VN and CO; per ton of V2O5The carbon consumption is 220 Kg-250 Kg, and the comprehensive power consumption can be controlled to 3000 remainders per ton of product.
4. The equipment occupies a small area, the heating device is not easy to damage, consumables such as graphite charging pots with high price, easy loss and large quantity are not needed, and the service life of the equipment is long.
Drawings
FIG. 1 is a process flow diagram of the present invention;
fig. 2 is a main flow process for producing vanadium-nitrogen alloy.
Detailed Description
The present invention will now be described by way of example with reference to FIG. 1. On the basis of the experimental device for preparing active aluminum powder by the original nitrogen atomization method, the experimental device is reformed, the atomizer is originally connected with the nitrogen pipe and is connected with the carbon powder gas conveying pipe, the preheater is additionally arranged on the gas conveying pipe, and the aluminum pipe is originally connected and is connected with the molten V2O5A liquid outlet pipe; the device is characterized in that a boiling bed device is additionally arranged and connected with an outlet of an atomizing chamber, a Venturi powder sprayer is additionally arranged and connected with the bottom of the boiling bed device, carbon powder can be supplemented while nitrogen is supplied, a heating carbon electrode is arranged on the wall of the atomizing chamber, a heating carbon electrode is also arranged on the lower portion of the boiling device, a cooling jacket is arranged on the upper portion of the boiling device, a mixer, a forging press, an atmosphere resistance furnace, a gas melting furnace, metering and stirring equipment are arranged, a cyclone separator for the first-stage dust removal and a bag type dust remover for the second-stage dust removal are additionally arranged, and after the device is transformed, the device is specifically operated as follows.
Firstly, pyrolyzing and melting vanadium compounds: under the condition of induced air, putting ammonium metavanadate powder into a calcining furnace, controlling the pyrolysis temperature to be 600-650 ℃, and pyrolyzing to obtain V2O5And absorbing the powder and the air in the induced duct by water to obtain ammonia water. Then, the V is put2O5Placing the powder in a melting furnace, controlling the temperature to be 690-750 ℃ to obtain molten V2O5And (4) liquid.
Secondly, atomizing and mixing: the preheated nitrogen gas mixture is used to pneumatically convey the carbon powder without oxygen to the atomizer to make molten V2O5Liquid is sucked into the atomizer and atomized and mixed at the outlet of the atomizer to form fine liquid-solid mixtureCombining the components, rapidly performing carbothermic reduction reaction and partial nitridation reaction in an atomization chamber to generate powder, controlling the particle size of the powder to be 100-200 um, and feeding the reaction powder and gas into a boiling device; the gas is used as a secondary gas source to participate in the reaction of the fluidized bed, the temperature of the atomization chamber is controlled to be 800-1000 ℃, and the pressure of the atomizer is controlled to be 0.5-2 MPa; v into the atomizer2O5And the carbon agent powder in a mass ratio of 1: 0.24, maintaining the molten state V2O5The liquid level is at a certain height to prevent air from entering, and nitrogen is used for replacing the gas in the atomizing chamber and the boiling device before atomization.
Boiling carbonization and nitridation: the reaction material entering the boiling device from the atomizing chamber forms a material layer in the furnace, the material layer state is controlled between the fixed bed and the fluidized bed for conversion, pure nitrogen is introduced from a blast cap at the bottom of the boiling device, the amount of the pure nitrogen is gradually increased, when the material layer starts to fluidize, the amount of the nitrogen entering the bottom of the boiling device is immediately reduced until the amount of the minimum gas velocity, then the amount of the nitrogen is slowly increased until the material layer starts to fluidize again, and when the material layer is periodically and repeatedly fluidized, the material layer is fixed and solidified; the gas phase and the solid phase are fully contacted, so that the incomplete carbonization reaction and the nitridation reaction are further accelerated; controlling the temperature of the lower section of the boiling device to be 1000-1200 ℃; the height of the fluidized bed material layer is 1 m-1.5 m, and the carbon agent and V are stopped2O5The liquid enters an atomizing chamber, the gas amount of nitrogen mixed gas is reduced, and the gas speed of a boiling device is controlled to be 0.2-3 m/s; a small amount of fine powder enters a first-stage cyclone separator from an outlet at the upper section of the boiling device for recovery, and returns to the boiling device again through an atomizer, and the temperature at the upper section of the boiling device is adjusted to 500-600 ℃ by a water-cooling jacket.
Fourthly, detecting and discharging; reacting the material layer of the boiling device for 1 hour, sampling at sampling ports at the lower section and the middle section of the boiling device, and adjusting V entering an atomizing chamber and a boiling nitriding furnace according to an analysis result when the component content of the powder is unqualified2O5Ratio to carbon powder and V2O5And N2And the proportion and the material layer residence time, when the product meets the quality control requirement, the product enters a cooler and is cooled to below 200 ℃, and vanadium-nitrogen alloy powder is discharged.
Fifthly, mixing materials and pressing for forming: analyzing the components of the vanadium-nitrogen alloy powder, determining the amount of added iron powder and a binder, and controlling the mass ratio of the vanadium-nitrogen alloy powder to the iron powder to be 1: 0.02-0.04, adding the binder after uniformly mixing, uniformly mixing and stirring, pressing the mixture into a spherical shape by a forging press or a roller press, and pressing the granularity of each finished product to be 30-40 mm.
And sixthly, sintering, namely heating the vanadium-nitrogen alloy ball in nitrogen atmosphere at the temperature of 1200-1400 ℃, further performing nitridation sintering, reacting for 1 hour, and cooling to below 200 ℃ to obtain a vanadium-nitrogen alloy finished product.
Preferably, the carbon agent powder is carbon black powder, the carbon content is more than 98.5%, the granularity is 300 meshes to 500 meshes, and the binder is sodium silicate.
Preferably, the material layer of the boiling device reaches 1-1.5 m, and the molten state V is stopped2O5And the carbon powder enters an atomizer, the gas amount of nitrogen gas mixture is reduced, the first stage and a dust remover are kept to recover the powder and enter an atomizing chamber, the sampling ports at the lower section and the middle section of the boiling device are used for sampling, the component content of the powder is analyzed, when the carbon content is less than 3 percent and the oxygen content is more than 4 percent, the carbon powder is supplemented while the nitrogen gas is fed from the bottom of the boiling device, the periodic fluidized reaction of a material layer is kept, and after the sampling is qualified, the vanadium-nitrogen alloy powder is discharged from the bottom of the boiling device; the feed is then reintroduced from the atomizer.
Preferably, the separator is provided with a water cooling jacket and a cooling coil, and the temperature of the outlet gas of the separator is controlled to be 200-300 ℃.
Preferably, the nitrogen gas mixture is pure nitrogen gas used in the production, then a part of tail gas at the outlet of the dust remover is cooled and pressurized, and then the pure nitrogen gas is mixed to be used as atomizing gas, and CO of the nitrogen gas mixture is used2And N2In a molar ratio of 1: 2; v into the atomising chamber2O5And N2In a molar ratio of 1: 2-3; the pure nitrogen gas refers to pure nitrogen gas with the nitrogen content of 99.999 percent.
Preferably, the amount of the doped pure iron powder or the amount of the iron oxide powder is accurately calculated according to the contents of vanadium, nitrogen, carbon and oxygen in the cooled and discharged vanadium-nitrogen alloy powder, the mixed material is pressed and formed and then enters a vacuum nitriding furnace for further pressurization and nitridation, the temperature is 1200-1400 ℃, the nitrogen content is increased within 1-8 hours of reaction time, and the vanadium-nitrogen alloy finished product with high nitrogen content is obtained, so that the requirement of the national standard VN19 brand is met.
Preferably, the vanadium-nitrogen alloy powder is prepared by adding pure iron powder firstly, uniformly mixing, heating to 1200-1500 ℃ in a nitrogen atmosphere sintering furnace, reacting for 3 hours, cooling to obtain a sintered block, grinding, adding a binder, pressing for molding, and drying at 200 ℃ in a dryer to obtain a vanadium-nitrogen alloy finished product with high apparent density.
The energy consumption of the vanadium-nitrogen alloy product produced by the method is compared with that of the existing product.
| Raw material crushing | Heating for reduction nitridation | Production of nitrogen | Power plant | Heating for sintering | Total up to | |
| Existing products | 25 degree | 3710 degree | 400 degree | 15 degrees | Is free of | 4150 deg. C |
| Products of the invention | Is free of | 2160 deg.C | 550 degree | 20 degree | 340 degree | 3070 degree |
2% of iron powder is added into the vanadium-nitrogen alloy powder produced by the method, and finally the vanadium-nitrogen alloy finished product is compared with the existing product.
| V | N | C | O | Fe + balance | Density of | |
| Content of existing product (%) | 77.32 | 15.24 | 3.55 | 1..62 | 0.8+1.47 | 3.2g/cm³ |
| Content of inventive product (%) | 77.24 | 15.93 | 2.73 | 0.73 | 1.97+1.40 | 3.8g/cm³ |
The foregoing shows and describes the general principles and features of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (9)
1. A high-efficiency vanadium-nitrogen alloy production process is characterized by comprising the following steps:
firstly, pyrolyzing and melting vanadium compounds: heating vanadium compound in a calcining furnace to 500-650 ℃ to obtain vanadium oxide and ammonia gas, then further oxidizing the vanadium oxide in oxygen-enriched mode, putting the vanadium oxide into a melting furnace, heating to 690-750 ℃ to obtain meltMelt state V2O5Liquid;
secondly, atomizing and mixing: the preheated nitrogen gas mixture is used to pneumatically convey the carbon powder without oxygen to the atomizer to make molten V2O5Liquid is sucked into an atomizer, atomized and mixed into a fine liquid-solid mixture at the outlet of the atomizer, and rapidly subjected to carbothermic reduction reaction and partial nitridation reaction in an atomization chamber to generate powder, the particle size of the powder is controlled to be 100-200 um, and the reaction powder and reaction gas enter a fluidized nitriding furnace together; reacting gas as a secondary gas source to participate in the reaction of the fluidized bed, controlling the temperature of an atomization chamber to be 800-1000 ℃, and controlling the pressure of an atomizer to be 0.5-2 MPa; v into the atomizer2O5And the carbon agent powder in a mass ratio of 1: 0.2 to 0.3;
boiling carbonization and nitridation: the reaction powder entering the boiling nitriding furnace from the atomizing chamber forms a material layer in the furnace, the material layer state is controlled between a fixed bed and a fluidized bed for conversion, nitrogen is introduced from a blast cap at the bottom of the boiling nitriding furnace, the nitrogen amount is gradually increased, when the material layer starts to fluidize, the nitrogen amount is immediately reduced until the minimum gas velocity amount is reached, then the nitrogen amount is slowly increased until the material layer starts to fluidize again, and when the material layer is periodically and repeatedly fluidized, the material layer is fixed and solidified; the gas and the solid are fully contacted, so that the incomplete carbonization reaction and the nitridation reaction are further accelerated; controlling the temperature of the lower section of the fluidized nitriding furnace to be 1000-1200 ℃; the temperature of the upper section of the fluidized bed nitriding furnace is 500-600 ℃; the height of the material layer of the fluidized bed is kept between 0.5m and 5m, and the gas speed of the fluidized nitriding furnace is controlled between 0.2 m/s and 6 m/s;
fourthly, detecting and discharging; the reaction retention time is kept by controlling the downward moving speed of the material layer of the fluidized bed furnace, the retention time is controlled to be 1-3 hours, sampling ports are arranged at the lower section and the middle section of the fluidized bed nitriding furnace, the powder component content is sampled and analyzed, and the V entering an atomizing chamber and the fluidized bed nitriding furnace is adjusted according to the analysis result2O5Ratio to carbon powder and V2O5And N2The proportion and the material layer residence time are controlled, when the product meets the quality control requirement, the product is cooled to below 200 ℃, and vanadium-nitrogen alloy powder is discharged;
fifthly, mixing materials and pressing for forming: analyzing the components of the vanadium-nitrogen alloy powder, determining the amount of added iron powder and a binder, and controlling the mass ratio of the vanadium-nitrogen alloy powder to the iron powder to be 1: 0.02-0.04, adding the binder after uniformly mixing, uniformly mixing and stirring, and pressing the mixture into balls by a forging press or a roller press, wherein the granularity of each finished product is 30-40 mm;
and sixthly, sintering, namely heating the vanadium-nitrogen alloy ball in nitrogen atmosphere at the temperature of 1200-1400 ℃, further performing nitridation sintering, reacting for 1-5 hours, and cooling to below 200 ℃ to obtain a vanadium-nitrogen alloy finished product.
2. The efficient vanadium-nitrogen alloy production process according to claim 1, wherein the amount of pure iron powder or iron oxide powder and carbon agent powder or vanadium oxide powder are accurately calculated according to the contents of vanadium, nitrogen, carbon and oxygen in the cooled discharged vanadium-nitrogen alloy powder, the mixed material is pressed and formed, and then enters a pressure-increasing nitriding furnace for further pressure nitridation, the pressure in the furnace is 0.2MPa, the temperature is 1200-1400 ℃, the nitrogen content is increased within 1-8 hours of reaction time, and a vanadium-nitrogen alloy finished product with high nitrogen content is obtained, so that the requirement of the national standard VN19 is met.
3. The high-efficiency vanadium-nitrogen alloy production process according to claim 1, wherein the vanadium-nitrogen alloy powder is added with pure iron powder and mixed uniformly, the mixture is put into a nitrogen atmosphere sintering furnace and heated to 1200-1500 ℃, the reaction is carried out for 1-3 hours and cooled to obtain a sintered block, the sintered block is added with a binder after being ground into powder and then is pressed and molded, and the mixture is dried at 200 ℃ to obtain a vanadium-nitrogen alloy finished product with high apparent density.
4. The process of claim 1, wherein when the vanadium compound is ammonium metavanadate or ammonium polyvanadate, the vanadium compound is pyrolyzed by isolating oxygen, the decomposed ammonia gas is purified and then used as a supplement of pure nitrogen gas, and then vanadium oxide is further oxidized and heated to molten state V by oxygen enrichment2O5When the vanadium compound is V2O5Directly heating and melting.
5. High efficiency vanadium according to claim 1Process for producing a nitrogen alloy, characterized in that said molten V2O5Before atomization, 0.5-2% of reduced iron powder or iron oxide powder is added into the molten liquid and uniformly stirred, the particle size of the atomized and mixed powder is further controlled, the reaction contact area is increased, and the reaction speed is accelerated, wherein the particle size of the reduced iron powder or the iron oxide powder is 75-120 um.
6. The process for producing a high-efficiency vanadium-nitrogen alloy according to claim 1, wherein the carbon agent powder is at least one of carbon black, low-sulfur petroleum coke powder, charcoal powder, activated carbon powder, graphite electrode powder and graphite powder, the carbon content is greater than 98.5%, the particle size is 300-500 meshes, the oxygen removal of the carbon agent powder is performed by filling nitrogen gas for replacement after vacuum pumping or replacing the oxygen removal with produced exhaust gas, and the binder is sodium water glass or potassium water glass or instant powdered sodium silicate or dextrin aqueous solution.
7. The high-efficiency vanadium-nitrogen alloy production process according to claim 1, wherein the boiling nitriding furnace layer reaches 0.5-5 m, and the molten V is stopped2O5And the carbon powder enters an atomizer, the gas amount of the nitrogen gas mixture is reduced, the separator and the dust remover are kept to recover the powder and enter an atomizing chamber, samples are taken from sampling ports at the lower section and the middle section of the boiling nitriding furnace, the component content of the powder is analyzed, when the carbon content is less than 3 percent and the oxygen content is more than 4 percent, the carbon powder is supplemented while pure nitrogen is fed from the bottom of the boiling nitriding furnace, the periodic fluidization reaction of a material layer is kept, and after the sampling is qualified, vanadium-nitrogen alloy powder is discharged; the raw materials enter the atomizer again for atomization and mixing.
8. The high-efficiency vanadium-nitrogen alloy production process as claimed in claim 1, wherein the pure nitrogen is preheated before entering the blast cap at the bottom of the fluidized bed nitriding furnace, the separator is provided with a water cooling jacket and a cooling coil, and the temperature of the outlet gas of the separator is controlled to be 200-300 ℃.
9. High efficiency vanadium according to claim 1The production process of the nitrogen alloy is characterized in that the nitrogen mixed gas is pure nitrogen or mixed gas obtained by mixing part of tail gas at the outlet of a dust remover with the pure nitrogen after cooling and pressurizing, and CO of the mixed gas2And N2In a molar ratio of 1: 1-3; v into the atomizer2O5And N2In a molar ratio of 1: 1-8; the pure nitrogen gas refers to pure nitrogen gas with the nitrogen content of 99.999 percent.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115522092A (en) * | 2022-10-25 | 2022-12-27 | 河南昱千鑫金属科技有限公司 | Production method of high-nitrogen low-carbon vanadium-nitrogen alloy |
| CN115637367A (en) * | 2022-10-21 | 2023-01-24 | 武汉科技大学 | Vanadium-nitrogen alloy based on vanadium compound and preparation method thereof |
| CN115679176A (en) * | 2022-10-21 | 2023-02-03 | 武汉科技大学 | Vanadium-nitrogen alloy based on vanadium pentoxide and preparation method thereof |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115637367A (en) * | 2022-10-21 | 2023-01-24 | 武汉科技大学 | Vanadium-nitrogen alloy based on vanadium compound and preparation method thereof |
| CN115679176A (en) * | 2022-10-21 | 2023-02-03 | 武汉科技大学 | Vanadium-nitrogen alloy based on vanadium pentoxide and preparation method thereof |
| CN115679176B (en) * | 2022-10-21 | 2023-09-22 | 武汉科技大学 | Vanadium-nitrogen alloy based on vanadium pentoxide and preparation method thereof |
| CN115522092A (en) * | 2022-10-25 | 2022-12-27 | 河南昱千鑫金属科技有限公司 | Production method of high-nitrogen low-carbon vanadium-nitrogen alloy |
| CN115522092B (en) * | 2022-10-25 | 2023-10-13 | 河南昱千鑫金属科技有限公司 | Production method of high-nitrogen low-carbon vanadium-nitrogen alloy |
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