Method for preparing vanadium-nitrogen alloy by laser coaxial powder feeding reduction nitriding

Abstract

The present application belongs to the new technology of steel alloy and its application field, and discloses a method for preparing vanadium-nitrogen alloy by laser coaxial powder feeding reduction and nitriding, and the process flow is as follows: powder feeding and carrying gas-gas blowing-laser irradiation-powder melting and solidification-casting roll ingot casting-smoke dust recovery.The method for laser melting reduction and nitriding in the present application has the advantages of energy concentration, high electric heat energy conversion efficiency and energy saving; and the vanadium oxide pellets are reduced and nitrided to form ingots, and the method for rotating the casting roll crucible realizes continuous smelting and casting operation, the production time is short, and the production efficiency of vanadium-nitrogen alloy is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of new technologies for steelmaking alloys and their applications, and provides a new method for rapidly and efficiently smelting high-nitrogen vanadium-nitrogen alloys by fully utilizing laser electrical energy. Background Technology

[0002] Vanadium-nitrogen alloys, currently the most widely used vanadium product, are extensively applied in steel metallurgy. Adding vanadium-nitrogen alloys during steelmaking, through vanadium-nitrogen microalloying technology, fully utilizes inexpensive nitrogen, optimizes vanadium precipitation, and thus better exerts its grain-refining and precipitation-strengthening effects, significantly improving the strength of the steel. In the production of vanadium nitride, the nitrogen content is a crucial indicator; higher nitrogen content results in better vanadium strengthening under the same conditions. Therefore, the nitrogen content of vanadium nitride also affects its selling price. National standards specify that vanadium containing 10%–14% nitrogen is called VN12, while vanadium containing 14%–18% nitrogen is called VN16. The price difference between the two is significant; the higher the nitrogen content, the higher the price.

[0003] The nitriding and reduction processes in the preparation of vanadium-nitrogen alloys are highly complex physicochemical processes. The main methods for preparation include: carbothermic reduction-nitriding (including two-step and one-step methods); microwave heating synthesis; plasma synthesis; temperature-programmed reduction precursor method; direct synthesis; and low-temperature synthesis. In the synthesis research and industrial production of vanadium nitride, the carbothermic reduction method is widely used. The raw materials used are mostly vanadium oxides such as ammonium metavanadate, ammonium polyvanadate, V₂O₅, and V₂O₃. H₂, C, NH₃, and CH₄ can be used as reducing agents, while nitriding agents mainly include NH₃, N₂, and other nitrogen-containing compounds.

[0004] Currently, the most common and relatively mature methods for producing vanadium-nitrogen alloys in industry are the pusher kiln method and the vertical medium-frequency furnace method. Both methods require long production times and have low energy utilization rates. The preparation of high-nitrogen-content vanadium-nitrogen alloys is particularly energy-intensive. Therefore, it is imperative to increase research, innovation, and breakthroughs to improve production efficiency using modern metallurgical materials technologies. The pusher kiln, evolved from the tunnel kiln, mainly consists of the kiln body, hydraulic circulation system, graphite sagger, water cooling system, air intake and exhaust system, and heating system. During production, the feed balls are placed inside the graphite sagger, which is continuously pushed forward from the kiln inlet and pushed out from the kiln outlet by a hydraulic pusher. With continuous nitrogen gas flow, the graphite sagger passes through each temperature range of the kiln sequentially. The feed balls undergo a reduction-nitriding reaction within the kiln, ultimately cooling to produce the vanadium-nitrogen alloy product. The main equipment of the vertical medium-frequency furnace method is the medium-frequency furnace. The overall system includes a rectifier section, an inverter section, and a furnace body. The furnace body is mainly composed of copper tube coils, graphite carbon liners, and furnace frames. It is divided into a preheating section, a heating section, and a cooling section. Its heating principle is that when the copper tube coils are energized, an induced current is generated in the graphite carbon liners. Due to the high resistance of the graphite carbon liners, they generate heat, thereby realizing the reduction and nitriding reaction of vanadium oxides at high temperatures.

[0005] The V and N content in products produced by pusher kilns is relatively stable compared to those produced by vertical induction furnaces, with minimal fluctuations in chemical composition. In contrast, vertical induction furnaces suffer from instability due to the varying heating characteristics of each furnace, random start-up and shutdown, and inconsistent ball adhesion. The vanadium-nitrogen alloys produced by pusher kilns exhibit a more complete and uniform appearance, significantly superior to those from vertical induction furnaces. This is primarily because the tightly packed balls during vertical induction furnace production, coupled with localized high temperatures during nitriding and reduction, cause the balls to melt and adhere together. Furthermore, the crushing process during discharge further damages the appearance of the balls.

[0006] This invention uses laser irradiation to prepare vanadium-nitrogen alloys, which is significantly different from traditional production methods. The resulting vanadium-nitrogen alloy products have a high nitrogen content, higher production efficiency, and are more energy-efficient. Summary of the Invention

[0007] In view of this, the present invention provides a method for preparing vanadium-nitrogen alloys by laser coaxial powder feeding reduction nitriding, which is a new process for rapidly and efficiently smelting high-nitrogen vanadium-nitrogen alloys by making full use of laser electrical energy, and is applicable to the improvement of existing steelmaking alloy production plant process technology.

[0008] To achieve the above-mentioned technical objectives, the technical solution disclosed in this invention is as follows: A method for preparing vanadium-nitrogen alloy by laser coaxial powder feeding reduction nitriding, the process flow is as follows: powder carrier gas feeding—gas blowing—laser irradiation—powder melting and solidification—casting roll ingot discharge—dust recovery.

[0009] First, the powder-carrying gas is continuously fed into the coaxial laser nozzle, and the gas jet pipe is activated to blow gas. The laser irradiator is turned on, and under the high-energy laser irradiation, the powder melts and is rapidly reduced and nitrided. The molten high-nitrogen vanadium-nitrogen alloy solidifies layer by layer in the casting roll crucible. As the amount of vanadium-nitrogen alloy solidified by the laser increases, the crucible is filled to form an alloy ingot. The casting roll rotates, and the casting roll crucible turns to the ingot exit position. The next adjacent casting roll crucible turns to the laser focus and continues to receive the solidified vanadium-nitrogen alloy. The gas containing CO and dust generated by the reaction is discharged and recovered from the furnace cavity through the exhaust pipe.

[0010] Furthermore, the powder-carrying gas is a gas carrying mixed powder, which includes carbon powder, vanadium oxide powder, and metallic vanadium powder.

[0011] Furthermore, the type of the injected gas is nitrogen or a mixture of nitrogen, argon, and ammonia, with the volume ratio of nitrogen being 70% to 100%.

[0012] Furthermore, the high-energy laser has a laser power of 1500W~6000W and a spot area diameter greater than 3mm that is adjustable.

[0013] Furthermore, the fast restoration time is 30ms to 30s.

[0014] Furthermore, the high-nitrogen vanadium-nitrogen alloy is a vanadium-nitrogen alloy with a nitrogen content of 20% to 26%.

[0015] Furthermore, the casting roll crucible is a crucible composed of a high-temperature refractory material layer and a copper metal layer.

[0016] As can be seen from the above technical solution, compared with the prior art, the present invention provides a method for preparing vanadium-nitrogen alloy by laser coaxial powder feeding reduction nitriding, which has the characteristics of high energy efficiency, continuity, and high nitrogen content. The specific superior effects are as follows: (1) Laser melting reduction and nitriding methods have concentrated energy, high electrothermal energy conversion efficiency, and save energy; (2) Vanadium oxide pellets are reduced and nitrided to form ingots, and the method of rotating the casting roll crucible realizes continuous smelting and solidification operations; (3) Short production time greatly improves the production efficiency of vanadium-nitrogen alloy; (4) The reaction nitriding has a large amount of nitrogen, which can produce high nitrogen vanadium-nitrogen alloys with a nitrogen content of up to 25%. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0018] Figure 1 A process flow diagram for preparing vanadium-nitrogen alloys by laser coaxial powder feeding reduction nitriding.

[0019] In the diagram: 1. Powder carrier gas; 2. Coaxial laser nozzle; 3. Jet pipe; 4. Laser irradiator; 5. Molten pool; 6. Casting roll crucible; 7. Alloy ingot; 8. Casting roll; 9. Pressure gauge; 10. Exhaust pipe; 11. Furnace cavity. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] The term "embodiment" used herein, as an example, is not necessarily to be construed as superior to or better than other embodiments. Performance testing in the embodiments of this application, unless otherwise specified, employs conventional testing methods in the art. It should be understood that the terminology used in this application is merely for describing particular implementations and is not intended to limit the scope of this disclosure.

[0022] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this application pertains; other experimental methods and techniques not specifically mentioned herein refer to experimental methods and techniques commonly used by one of ordinary skill in the art. Without conflict, the technical features disclosed in the embodiments of this application can be arbitrarily combined, and the resulting technical solutions belong to the content disclosed in the embodiments of this application.

[0023] To better understand the present invention, the following embodiments are provided for further detailed description of the present invention, but they should not be construed as limiting the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are also considered to fall within the protection scope of the present invention. Example 1

[0024] Following the method of preparing vanadium-nitrogen alloy by laser coaxial powder feeding reduction nitriding, the process flow was implemented as follows: "powder carrier gas feeding - gas blowing - laser irradiation - powder melting and solidification - casting roll ingot discharge - dust recovery".

[0025] First, a powder-carrying gas containing a mixture of carbon powder, vanadium oxide powder, and metallic vanadium powder is continuously fed into the coaxial laser nozzle. At the same time, the jet pipe is activated to spray a mixture of nitrogen, argon, and ammonia, with nitrogen accounting for 80% of the volume, argon for 10%, and ammonia for 10%. The laser irradiator is then turned on, and under high-energy laser irradiation with a laser power of 3000W and a spot diameter of 5mm, the powder melts and rapidly undergoes reduction nitriding, maintaining the reduction nitriding time for 10s.

[0026] The molten vanadium-nitrogen alloy with a nitrogen content of 25% solidifies layer by layer in a casting roll crucible composed of a high-temperature refractory material layer and a copper metal layer. As the amount of laser-melted vanadium-nitrogen alloy increases, the crucible is filled to form an alloy ingot.

[0027] As the casting roll rotates, the casting roll crucible turns to the ingot discharge position, and the adjacent next casting roll crucible rotates to the laser focus to continue receiving the molten vanadium-nitrogen alloy. The gas containing CO and dust generated in the reaction is continuously discharged and recovered. Example 2

[0028] Following the method of preparing vanadium-nitrogen alloy by laser coaxial powder feeding reduction nitriding, the process flow was implemented as follows: "powder carrier gas feeding - gas blowing - laser irradiation - powder melting and solidification - casting roll ingot discharge - dust recovery".

[0029] First, a powder-carrying gas containing a mixture of carbon powder, vanadium oxide powder, and metallic vanadium powder is continuously fed into the coaxial laser nozzle. At the same time, the jet pipe is activated to spray a mixture of nitrogen, argon, and ammonia, with nitrogen accounting for 70% of the volume, argon for 5%, and ammonia for 25%. The laser irradiator is then turned on, and under high-energy laser irradiation with a laser power of 5000W and a spot diameter of 6mm, the powder melts and rapidly undergoes reduction nitriding, maintaining the reduction nitriding time for 5 seconds.

[0030] The molten vanadium-nitrogen alloy with a nitrogen content of 23% solidifies layer by layer in a casting roll crucible composed of a high-temperature refractory material layer and a copper metal layer. As the amount of laser-melted vanadium-nitrogen alloy increases, the crucible is filled to form an alloy ingot.

[0031] As the casting roll rotates, the casting roll crucible turns to the ingot discharge position, and the adjacent next casting roll crucible rotates to the laser focus to continue receiving the molten vanadium-nitrogen alloy. The gas containing CO and dust generated in the reaction is continuously discharged and recovered. Example 3

[0032] Following the method of preparing vanadium-nitrogen alloy by laser coaxial powder feeding reduction nitriding, the process flow was implemented as follows: "powder carrier gas feeding - gas blowing - laser irradiation - powder melting and solidification - casting roll ingot discharge - dust recovery".

[0033] First, a powder-carrying gas containing a mixture of carbon powder, vanadium oxide powder, and metallic vanadium powder is continuously fed into the coaxial laser nozzle. At the same time, the jet pipe is activated to spray a mixture of nitrogen, argon, and ammonia, with nitrogen volume ratio of 100%, argon volume ratio of 0%, and ammonia volume ratio of 0%. The laser irradiator is turned on, and under high-energy laser irradiation with a laser power of 1500W and a spot area diameter of 8mm, the powder melts and rapidly undergoes reduction nitriding, maintaining the reduction nitriding time for 20s.

[0034] The molten vanadium-nitrogen alloy with a nitrogen content of 20% solidifies layer by layer in a casting roll crucible composed of a high-temperature refractory material layer and a copper metal layer. As the amount of laser-melted vanadium-nitrogen alloy increases, the crucible is filled to form an alloy ingot.

[0035] As the casting roll rotates, the casting roll crucible turns to the ingot discharge position, and the adjacent next casting roll crucible rotates to the laser focus to continue receiving the molten vanadium-nitrogen alloy. The gas containing CO and dust generated in the reaction is continuously discharged and recovered. Example 4

[0036] Following the method of preparing vanadium-nitrogen alloy by laser coaxial powder feeding reduction nitriding, the process flow was implemented as follows: "powder carrier gas feeding - gas blowing - laser irradiation - powder melting and solidification - casting roll ingot discharge - dust recovery".

[0037] First, a powder-carrying gas containing a mixture of carbon powder, vanadium oxide powder, and metallic vanadium powder is continuously fed into the coaxial laser nozzle. At the same time, the jet pipe is activated to spray a mixture of nitrogen, argon, and ammonia, with nitrogen accounting for 75% of the volume, argon for 10%, and ammonia for 15%. The laser irradiator is then turned on, and under high-energy laser irradiation with a laser power of 4000W and a spot diameter of 6mm, the powder melts and rapidly undergoes reduction nitriding, maintaining the reduction nitriding time for 4 seconds.

[0038] The molten vanadium-nitrogen alloy with a nitrogen content of 21% solidifies layer by layer in a casting roll crucible composed of a high-temperature refractory material layer and a copper metal layer. As the amount of laser-melted vanadium-nitrogen alloy increases, the crucible is filled to form an alloy ingot.

[0039] As the casting roll rotates, the casting roll crucible turns to the ingot discharge position, and the adjacent next casting roll crucible rotates to the laser focus to continue receiving the molten vanadium-nitrogen alloy. The gas containing CO and dust generated in the reaction is continuously discharged and recovered.

[0040] Other improvements made by those skilled in the art based on the above-described invention, without inventive effort, are also considered to fall within the protection scope of this invention. The above description of the disclosed embodiments enables those skilled in the art to implement or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing vanadium-nitrogen alloys by laser coaxial powder feeding reduction nitriding, characterized in that, The process flow is as follows: powder-carrying gas feeding—gas blowing—laser irradiation—powder melting and solidification—casting roll ingot exit—dust recovery; the method specifically includes the following steps: First, the powder-carrying gas is continuously fed into the coaxial laser nozzle, while the jet pipe is activated to blow gas and the laser irradiator is turned on. Under high-energy laser irradiation, the powder melts and rapidly undergoes reduction and nitriding. The molten high-nitrogen vanadium-nitrogen alloy solidifies layer by layer in the casting roll crucible. As the amount of laser-melted vanadium-nitrogen alloy increases, the crucible fills up to form an alloy ingot. The casting roll rotates, and the casting roll crucible turns to the ingot exit position. The next adjacent casting roll crucible rotates to the laser focus to continue receiving the molten vanadium-nitrogen alloy. The gas containing CO and dust generated by the reaction is discharged and recovered from the furnace cavity through the exhaust pipe. The high-nitrogen vanadium-nitrogen alloy is a vanadium-nitrogen alloy with a nitrogen content of 20% to 26%.

2. The method for preparing vanadium-nitrogen alloy by laser coaxial powder feeding reduction nitriding according to claim 1, characterized in that, The powder-carrying gas is a gas carrying mixed powder, which includes carbon powder, vanadium oxide powder, and metallic vanadium powder.

3. The method for preparing vanadium-nitrogen alloy by laser coaxial powder feeding reduction nitriding according to claim 1, characterized in that, The type of gas to be injected is nitrogen or a mixture of nitrogen, argon and ammonia, with nitrogen accounting for 70% to 100% of the volume.

4. The method for preparing vanadium-nitrogen alloy by laser coaxial powder feeding reduction nitriding according to claim 1, characterized in that, The high-energy laser has a power of 1500W to 6000W and a spot area diameter greater than 3mm that is adjustable.

5. The method for preparing vanadium-nitrogen alloy by laser coaxial powder feeding reduction nitriding according to claim 1, characterized in that, The fast restoration time is 30ms to 30s.

6. The method for preparing vanadium-nitrogen alloy by laser coaxial powder feeding reduction nitriding according to claim 1, characterized in that, The casting roller crucible is a composite crucible made of a high-temperature refractory material layer and a copper metal layer.

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