An intermediate-temperature roasting furnace for vanadium-nitrogen alloy

Abstract

The present invention relates to a medium-temperature roasting furnace for vanadium-nitrogen alloy. The technical solution is as follows: There are three ammonia buffer chambers and a discharge chute (17) at the bottom of the furnace body (9). The inclined plane at the top of the three ammonia buffer chambers is also the bottom of the boiling chamber (14). The inclined plane is provided with tuyeres (15), and the three ammonia buffer chambers are connected to the corresponding blowers. Between the inner wall and the outer wall of the furnace body (9), a preheating electric heating wire group (4) and a heating electric heating wire group (7) are provided from the bottom upwards. The boiling chamber (14) is provided with a feeder (12), a return port (13) and a cyclone separator inlet (11); the feed inlet of the feed pipe (8) communicates with the feeder (12), the cyclone separator inlet (11) is connected to the cyclone separator (20) through a pipeline, the conical bottom end at the lower part of the cyclone separator (20) communicates with the return port (13) through a return pipe (19), and the cyclone separator (18) is provided with a cyclone separator outlet (10) at the top. The structure of the present invention is simple, can automatically discharge materials, is convenient to operate and has low energy consumption. It is not only suitable for ammonia roasting, but also has high raw material utilization rate and good roasting quality.

Description

Technical Field

[0001] The present invention belongs to the technical field of medium-temperature roasting furnaces. Specifically, it relates to a medium-temperature roasting furnace for vanadium-nitrogen alloy. Background Art

[0002] Vanadium-nitrogen alloy is a newly emerging alloy additive, which improves the strength of steel through grain refinement and precipitation strengthening in steel, and at the same time achieves the effects of vanadium addition and nitrogen addition. The carbothermal reduction method is a method that has realized the large-scale industrial application of vanadium-nitrogen alloy. This technology generally uses raw materials such as vanadium pentoxide and vanadium trioxide as vanadium sources, and directly reduces or indirectly reduces them in a roasting furnace under a nitrogen atmosphere at a high temperature (1400 - 1500 °C) to obtain qualified vanadium-nitrogen alloy products. The current design and improvement of vanadium-nitrogen alloy roasting furnaces generally match the existing high-temperature carbothermal reduction technology of vanadium-nitrogen alloy.

[0003] The patented technology of "A sintering furnace for producing vanadium-nitrogen alloy" (CN 112556404 A) provides a sintering furnace for producing vanadium-nitrogen alloy. By setting a step conveyor plate, it improves the productivity of vanadium-nitrogen alloy and facilitates the installation and maintenance of the equipment; the sintering furnace is also provided with an air suction and ventilation mechanism at the same time, which ensures the simultaneous progress of alloy carbonization and nitridation, reduces resource consumption, improves the production efficiency of vanadium-nitrogen alloy, and improves the purity of vanadium-nitrogen alloy. Since this equipment is an improvement of the traditional vanadium-nitrogen alloy pusher kiln, although it can improve the productivity of vanadium-nitrogen alloy, it is still difficult to overcome the problems of low reaction efficiency, high roasting temperature, and long reaction time.

[0004] The patented technology of "A production equipment for vanadium-nitrogen alloy" (CN 112696926 A) facilitates the batch production of vanadium-nitrogen alloy blanks by setting step conveyor wheels, improves the production efficiency of vanadium-nitrogen alloy, reduces the labor intensity of manual operation, and is conducive to realizing the automatic control of the production process; the equipment is also provided with a lifting mechanism at the same time, which is convenient for controlling the quality of vanadium-nitrogen alloying. However, the equipment has cumbersome feeding, great difficulty in disassembly and maintenance, and does not recycle the generated powder waste.

[0005] The patented technology of "A high-temperature reaction furnace based on the preparation of vanadium-nitrogen alloy" (CN 215638782 U) drives the driving gear by a motor, and then under the transmission of the driven gear, the two gas pipelines rotate synchronously. While the stirring rods on the outer wall of the gas pipeline stir the billets, nitrogen gas is introduced into the billet pile in an internal gas outlet manner through the air outlet holes. Compared with the traditional method of blowing nitrogen gas on the surface of the billets, it increases the contact area between nitrogen gas and the billets, reduces the reaction dead angle, enables each billet to fully react with nitrogen gas, and improves the production efficiency of vanadium-nitrogen alloy. Although this equipment solves the problem of low gas-solid reaction efficiency, the roasting temperature is still relatively high, and this equipment is only suitable for roasting in a nitrogen atmosphere.

[0006] In summary, the current vanadium-nitrogen alloy sintering kiln has technical defects such as cumbersome feeding equipment propulsion, high roasting temperature, long reaction time, difficulty in recovering powder materials, low gas-solid reaction efficiency, and only being applicable to roasting under nitrogen conditions. Summary of the Invention

[0007] The present invention aims to overcome the defects of the prior art, and the purpose is to provide a medium-temperature roasting furnace for vanadium-nitrogen alloy with a simple structure, convenient operation, low energy consumption, high raw material utilization rate, and automatic discharging function. This roasting furnace is not only applicable to ammonia roasting, but also has high roasting efficiency and good roasting quality.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] The furnace body of the medium-temperature roasting furnace for vanadium-nitrogen alloy is a hollow square column composed of an outer wall, a furnace bottom, and a furnace top. An inner wall is coaxially arranged inside the outer wall. The cross-sections of both the outer wall and the inner wall are rectangular, and the distance between the inner wall and the outer wall of the furnace body is equal. A "hui"-shaped space is formed between the inner wall and the outer wall of the furnace body.

[0010] At the bottom of the furnace body, a first ammonia buffer chamber, a second ammonia buffer chamber, a third ammonia buffer chamber, and a discharge chute are successively arranged from left to right. The outlets of the first blower, the second blower, and the third blower are communicated with the bottoms of the corresponding first ammonia buffer chamber, second ammonia buffer chamber, and third ammonia buffer chamber through their respective air ducts, and the inlets of the first blower, the second blower, and the third blower are communicated with the ammonia gas source.

[0011] The tops of the first ammonia buffer chamber, the second ammonia buffer chamber, and the third ammonia buffer chamber are the same inclined plane, and the inclined plane is an inclined plane with a higher left side and a lower right side. The included angle α between the inclined plane and the vertical plane is 95° - 110°; the space from the inclined plane to the top of the furnace body is the boiling chamber, and the inclined plane is also the bottom of the boiling chamber. Air caps are evenly arranged on the inclined plane. The first ammonia buffer chamber, the second ammonia buffer chamber, and the third ammonia buffer chamber are communicated with the boiling chamber through the air caps arranged on their respective tops.

[0012] The discharge chute is surrounded by the front inner wall, the rear inner wall, the left inner wall of the furnace body, and the right side wall of the third ammonia buffer chamber. An outlet is arranged at the middle position of the bottom of the discharge chute, and a valve is arranged at the end of the outlet; discharge plates are symmetrically arranged on the front and rear sides of the outlet. The upper ends of the two discharge plates are symmetrically close to the inner walls on their respective same sides, and the upper ends of the two discharge plates are respectively flush with the right side of the inclined plane; the lower ends of the two discharge plates are symmetrically located beside the outlet, and the widths of the two discharge plates are equal to the width of the discharge chute.

[0013] At the top of the rear side wall of the furnace body, there is an inlet of the cyclone separator, and the inlet of the cyclone separator is directly above the third ammonia buffer chamber; in the middle of the rear side wall of the furnace body, there is a return port, and at the upper middle part of the left side wall of the furnace body, there is a feed pipe. The upper end of the feed pipe is externally connected to a feeding device, and the feed inlet of the feed pipe communicates with the distributor. The distributor is horizontally arranged close to the left inner wall, and the height of the distributor from the furnace bottom is 0.5 - 0.7 times the height of the furnace body, and the height of the return port is the same as that of the distributor.

[0014] The inlet of the cyclone separator is connected to the cyclone separator through a channel. At the middle position of the top of the cyclone separator, there is an outlet of the cyclone separator, and the outlet of the cyclone separator is connected to an external waste gas treatment system; the lower part of the cyclone separator is conical, and the lower port of the cone communicates with the return port through a return pipe; the angle β between the return pipe and the horizontal plane is 10° - 30°.

[0015] At the bottom of the "return" - shaped space, a pre - heating electric heating wire group and a heating electric heating wire group are successively arranged from bottom to top; the pre - heating electric heating wire group is at the same height as the adjacent first ammonia buffer chamber, and the height of the pre - heating electric heating wire group is 0.2 - 0.25 times the height of the furnace body. The pre - heating electric heating wire group heats the first ammonia buffer chamber, the second ammonia buffer chamber and the third ammonia buffer chamber; the height of the heating electric heating wire group is the same as that of the pre - heating electric heating wire group, and the heating electric heating wire group heats the boiling chamber.

[0016] The length of the boiling chamber is 10 - 20m, and the width of the boiling chamber is 0.5 - 0.65 times the length of the boiling chamber.

[0017] The width of the first ammonia buffer chamber is 13 - 15% of the length of the boiling chamber, the width of the discharge chute is 2 - 5% of the length of the boiling chamber, and the widths of the second ammonia buffer chamber and the third ammonia buffer chamber are each half of the remaining length of the boiling chamber.

[0018] Due to adopting the above - mentioned technical solution, the present invention has the following positive effects compared with the prior art:

[0019] (1) Simple operation. According to the characteristics of different stages of the roasting reaction and the density change of the roasting raw materials during the reaction process, a pre - heating electric heating wire group and a heating electric heating wire group are successively arranged from bottom to top in the "return" - shaped space, which can control the temperature of the three ammonia buffer chambers (the first ammonia buffer chamber, the second ammonia buffer chamber and the third ammonia buffer chamber) and the upper and lower spaces of the boiling chamber in sections. The first blower, the second blower and the third blower communicate with the bottoms of the corresponding first ammonia buffer chamber, the second ammonia buffer chamber and the third ammonia buffer chamber through their respective air ducts, effectively realizing the sectional control of the air pressure in the three ammonia buffer chambers; the operation is simple.

[0020] (2) Simple structure. The inclined planes at the tops of the first ammonia buffer chamber, the second ammonia buffer chamber, and the third ammonia buffer chamber of the present invention also serve as the bottom of the boiling chamber, that is, the bottom of the boiling chamber is an inclined plane that is higher on the left and lower on the right, enabling the roasted raw materials to automatically flow from the left side of the boiling chamber to the right side to the discharge chute; in addition, the discharge port is arranged at the middle position at the bottom of the discharge chute, and inclined discharge plates are symmetrically arranged on both sides of the discharge port. The upper ends of the discharge plates are flush with the bottom of the boiling chamber. The roasted raw materials flow to the discharge port through the discharge plates, avoiding mechanical transmission and realizing automatic discharging, with a simple structure.

[0021] (3) Low energy consumption. The present invention enables the roasted raw materials to be roasted in a boiling chamber with an inclined plane at the bottom. The roasted raw materials automatically move downward under the combined action of gas and their own gravity, without mechanical transmission, realizing good airtightness in an ammonia atmosphere and being suitable for ammonia roasting; while the existing carbothermal reduction nitridation technology matched with roasting equipment mainly uses static roasting, with a mechanical transmission mechanism inside, and it is difficult to ensure the airtightness of the roasting furnace and cannot be directly used for roasting in an ammonia atmosphere.

[0022] Therefore, the present invention can not only cause the nitridation reaction of vanadium oxide to occur, but also realize the medium-temperature preparation of vanadium nitride alloy at a significantly lower roasting temperature than the existing one, significantly reducing the roasting energy consumption.

[0023] (4) Short roasting time and high efficiency. The existing vanadium nitride alloy roasting furnace mainly uses static roasting, while the present invention uses dynamic roasting in which ammonia is preheated in the ammonia buffer chamber and flows from bottom to top, forming an upward "blowing force" on the roasted raw materials. The roasted raw materials are in a "boiling" state under the combined action of the "blowing force" and "gravity". The gas and solid particles are violently turbulent in the boiling chamber, accelerating the mass transfer process between the gas and solid phases, increasing the reaction rate, and at the same time accelerating the heat exchange rate. The temperature in the boiling chamber is more uniform, avoiding local overheating in the boiling chamber. The roasting time is shortened to 5 - 10 minutes, with a short production cycle and high efficiency.

[0024] (5) The powder in the waste gas can be recycled, and the raw material utilization rate is high. The lower part of the cyclone separator of the present invention is conical, and the lower port of the cone communicates with the return port through a return pipe. The water vapor in the nitridation reaction product and the powder in the waste gas enter the cyclone separator together. The water vapor condenses into water droplets and mixes with the powder, and automatically agglomerates into small particles in the conical space at the lower part of the cyclone separator. The agglomerated small particles enter the boiling chamber through the return pipe for re-roasting. Therefore, there is less powder in the waste gas, the reaction is complete, the waste gas is easy to treat, and the raw material utilization rate can be significantly improved.

[0025] (6) Clean and environmentally friendly, high roasting quality. The ammonia "blown in" by the blower of the present invention serves as both a reducing agent and a nitriding agent for preparing vanadium nitride alloy at the same time. During the roasting process, no additional carbon powder reducing agent needs to be added, and there is no CO during the roasting process2 、 CO and other gases are generated, and the reaction products are mainly vanadium nitride and water vapor. The roasted vanadium nitride (vanadium-nitrogen alloy) has a high N content, is clean and environmentally friendly.

[0026] Therefore, the present invention has the characteristics of simple structure, convenient operation, low energy consumption, high raw material utilization rate, and automatic discharging. This roasting furnace is suitable for ammonia roasting, with high roasting efficiency and good quality. Description of the Drawings

[0027] Figure 1 is a schematic structural diagram of the present invention;

[0028] Figure 2 is Figure 1 the A-A cross-sectional view schematic diagram of

[0029] Figure 3 is Figure 1 the B-B cross-sectional view schematic diagram of

[0030] Figure 4 is the present invention with V 2 O 5 as the roasting raw material, the XRD pattern analysis of the roasted material obtained under different temperature conditions;

[0031] Figure 5 is the present invention with V 2 O 3 as the roasting raw material, the XRD pattern analysis of the roasted material obtained under different temperature conditions. Detailed Embodiments

[0032] The following further elaborates the present invention in conjunction with the drawings and specific embodiments, and does not limit its protection scope.

[0033] Example 1

[0034] A medium-temperature roasting furnace for vanadium-nitrogen alloy. As Figure 1 and Figure 3 shown, the furnace body 9 of the medium-temperature roasting furnace for vanadium-nitrogen alloy is a hollow square column composed of an outer wall, a furnace bottom and a furnace top. An inner wall is coaxially arranged inside the outer wall. The cross-sections of both the outer wall and the inner wall are rectangles, and the distance between the inner wall and the outer wall of the furnace body 9 is equal. A "hui" - shaped space is formed between the inner wall and the outer wall of the furnace body 9.

[0035] As Figure 1As shown in the figure, at the bottom of the furnace body 9, a first ammonia buffer chamber 6, a second ammonia buffer chamber 5, a third ammonia buffer chamber 16 and a discharge chute 17 are successively arranged from left to right. The outlets of the first blower 3, the second blower 2 and the third blower 1 are communicated with the bottoms of the corresponding first ammonia buffer chamber 6, second ammonia buffer chamber 5 and third ammonia buffer chamber 16 through their respective air ducts, and the inlets of the first blower 3, the second blower 2 and the third blower 1 are communicated with the ammonia gas source.

[0036] As Figure 1 shown in the figure, the tops of the first ammonia buffer chamber 6, the second ammonia buffer chamber 5 and the third ammonia buffer chamber 16 are on the same inclined plane, and the inclined plane is an inclined plane with a higher left side and a lower right side. The included angle α between the inclined plane and the vertical plane is 105°; the space from the inclined plane to the top of the furnace body 9 is the boiling chamber 14, and the inclined plane is also the bottom of the boiling chamber 14. Air caps 15 are evenly arranged on the inclined plane, and the first ammonia buffer chamber 6, the second ammonia buffer chamber 5 and the third ammonia buffer chamber 16 are communicated with the boiling chamber 14 through the air caps 15 arranged at their respective tops.

[0037] As Figure 1 、 Figure 3 shown in the figure, the discharge chute 17 is surrounded by the front inner wall, the rear inner wall, the left inner wall of the furnace body 9 and the right side wall of the third ammonia buffer chamber 16. An outlet 18 is arranged at the middle position of the bottom of the discharge chute 17, and a valve is arranged at the end of the outlet 18; discharge plates are symmetrically arranged on the front and rear sides of the outlet 18, and the upper ends of the two discharge plates are symmetrically close to the inner walls on their respective same sides, and the upper ends of the two discharge plates are respectively flush with the right side of the inclined plane; the lower ends of the two discharge plates are symmetrically located beside the outlet 18, and the widths of the two discharge plates are equal to the width of the discharge chute 17.

[0038] As Figure 1 and Figure 2 shown in the figure, a cyclone separator inlet 11 is arranged at the top of the rear side wall of the furnace body 9, and the cyclone separator inlet 11 is located directly above the third ammonia buffer chamber 16; a return port 13 is arranged in the middle of the rear side wall of the furnace body 9, and a feed pipe 8 is arranged at the upper middle part of the left side wall of the furnace body 9. The upper end of the feed pipe 8 is externally connected to a feeding device, and the feed inlet of the feed pipe 8 is communicated with a distributor 12. The distributor 12 is horizontally arranged close to the left inner wall, and the height of the distributor 12 from the furnace bottom is 0.6 times the height of the furnace body 9. The return port 13 has the same height as the distributor 12.

[0039] As Figure 2 shown in the figure, the cyclone separator inlet 11 is communicated with a cyclone separator 20 through a channel. A cyclone separator outlet 10 is arranged at the middle position of the top of the cyclone separator 20, and the cyclone separator outlet 10 is communicated with an external waste gas treatment system; the lower part of the cyclone separator 20 is conical, and the lower port of the cone is communicated with the return port 13 through a return pipe 19; the included angle β between the return pipe 19 and the horizontal plane is 20°.

[0040] As Figures 1 to 3 shown, a preheating electric heating wire group 4 and a heating electric heating wire group 7 are successively arranged upward from the bottom of the "hui"-shaped space; the preheating electric heating wire group 4 is at the same height as the adjacent first ammonia buffer chamber 6, the height of the preheating electric heating wire group 4 is 0.23 times the height of the furnace body 9, and the preheating electric heating wire group 4 heats the first ammonia buffer chamber 6, the second ammonia buffer chamber 5 and the third ammonia buffer chamber 16; the height of the heating electric heating wire group 7 is the same as that of the preheating electric heating wire group 4, and the heating electric heating wire group 7 heats the boiling chamber 14.

[0041] The length of the boiling chamber 14 is 15 m, and the width of the boiling chamber 14 is 0.6 times the length of the boiling chamber 14.

[0042] The width of the first ammonia buffer chamber 6 is 14% of the length of the boiling chamber 14, the width of the discharge chute 17 is 4% of the length of the boiling chamber 14, and the widths of the second ammonia buffer chamber 5 and the third ammonia buffer chamber 16 are each half of the remaining length of the boiling chamber 14.

[0043] Example 2

[0044] A medium-temperature roasting furnace for vanadium-nitrogen alloy. Except for the following technical parameters: the rest are the same as in Example 1:

[0045] The included angle α between the inclined plane and the vertical plane is 95°;

[0046] The height of the distributor 12 from the furnace bottom is 0.5 times the height of the furnace body 9;

[0047] The included angle β between the return pipe 19 and the horizontal plane is 10°;

[0048] The height of the preheating electric heating wire group 4 is 0.2 times the height of the furnace body 9;

[0049] The length of the boiling chamber 14 is 10 m, and the width of the boiling chamber 14 is 0.5 times the length of the boiling chamber 14;

[0050] The width of the first ammonia buffer chamber 6 is 13% of the length of the boiling chamber 14, and the width of the discharge chute 17 is 2% of the length of the boiling chamber 14.

[0051] Example 3

[0052] A medium-temperature roasting furnace for vanadium-nitrogen alloy. Except for the following technical parameters: the rest are the same as in Example 1:

[0053] The included angle α between the inclined plane and the vertical plane is 110°;

[0054] The height of the distributor 12 from the furnace bottom is 0.7 times the height of the furnace body 9;

[0055] The included angle β between the return pipe 19 and the horizontal plane is 30°;

[0056] The height of the preheating electric heating wire group 4 is 0.25 times the height of the furnace body 9;

[0057] The length of the boiling chamber 14 is 20 m, and the width of the boiling chamber 14 is 0.65 times the length of the boiling chamber 14;

[0058] The width of the first ammonia buffer chamber 6 is 15% of the length of the boiling chamber 14, and the width of the discharge chute 17 is 5% of the length of the boiling chamber 14.

[0059] Due to the adoption of the above technical solutions, the present invention has the following positive effects compared with the prior art:

[0060] (1) Simple operation. In view of the characteristics of different stages of the roasting reaction and the density change of the roasting raw materials during the reaction process in this specific embodiment, a preheating electric heating wire group 4 and a heating electric heating wire group 7 are successively arranged upward from the bottom of the "return" - shaped space, which can control the temperature of the upper and lower spaces of the three ammonia buffer chambers, namely the first ammonia buffer chamber 6, the second ammonia buffer chamber 5, and the third ammonia buffer chamber 16, and the boiling chamber 14 in sections. The first blower 3, the second blower 2, and the third blower 1 are communicated with the bottom of the corresponding first ammonia buffer chamber 6, the bottom of the second ammonia buffer chamber 5, and the bottom of the third ammonia buffer chamber 16 through their respective air ducts, effectively realizing the sectional control of the air pressure in the three ammonia buffer chambers, and the operation is simple.

[0061] (2) Simple structure. The inclined planes at the tops of the first ammonia buffer chamber 6, the second ammonia buffer chamber 5, and the third ammonia buffer chamber 16 in this specific embodiment are also the bottom of the boiling chamber 14, that is, the bottom of the boiling chamber 14 is an inclined plane with a higher left side and a lower right side, which can realize the automatic flow of the roasting raw materials from the left side to the right side of the boiling chamber 14 to the discharge chute 17; in addition, the discharge port 18 is arranged at the middle position of the bottom of the discharge chute 17, and inclined discharge plates are symmetrically arranged on both sides of the discharge port 18, and the upper ends of the discharge plates are flush with the bottom of the boiling chamber 14. The roasted materials flow to the discharge port 18 through the discharge plates, avoiding mechanical transmission and realizing automatic discharging, and the structure is simple.

[0062] (3) Low energy consumption. The present invention can roast the roasting raw materials in the boiling chamber 14 with an inclined plane at the bottom. The roasting raw materials move automatically to the lower place under the combined action of gas and its own gravity, without mechanical transmission, realizing good airtightness in the ammonia atmosphere and being suitable for ammonia roasting; while the existing carbothermal reduction nitridation technology matched with roasting equipment mainly adopts static roasting, with a mechanical transmission mechanism inside, and it is difficult to ensure the airtightness of the roasting furnace and cannot be directly used for roasting in an ammonia atmosphere.

[0063] The XRD pattern analysis of the calcined material obtained by this specific embodiment is as shown in the attached figure, Figure 4 which is the XRD pattern analysis of the calcined material obtained by using V 2 O 5 as the calcination raw material under different temperature conditions; Figure 5 which is the XRD pattern analysis of the calcined material obtained by using V 2 O 3 as the calcination raw material under different temperature conditions. It can be seen from Figure 4 that the calcined product obtained above 750 °C is pure-phase VN; it can be seen from Figure 5 that the calcined product obtained above 800 °C is pure-phase VN, indicating that the calcination temperature of this specific embodiment is low, effectively reducing the energy consumption.

[0064] Therefore, this specific embodiment can not only make the nitridation reaction of vanadium oxide occur, but also realize the medium-temperature preparation of vanadium nitride alloy at a significantly lower temperature than the existing calcination temperature, can significantly reduce the calcination temperature, and has low energy consumption.

[0065] (4) Short calcination time and high efficiency. The existing vanadium nitride alloy calcination furnace mainly uses static calcination, while this specific embodiment uses dynamic calcination in which ammonia gas flows upward after being preheated in the ammonia buffer chamber, forming an upward "blowing force" on the calcination raw material. The calcination raw material is in a "boiling" state under the combined action of the "blowing force" and "gravity". The gas and solid particles are violently turbulent in the boiling chamber 14, accelerating the mass transfer process between the gas and solid phases, increasing the reaction rate, and at the same time accelerating the heat exchange rate. The temperature in the boiling chamber 14 is more uniform, avoiding local overheating in the boiling chamber 14. The calcination time is shortened to 5 - 10 min, the production cycle is short, and the efficiency is high.

[0066] (5) The powder in the waste gas can be recycled, and the gas-solid reaction efficiency is high. In this specific embodiment, the lower part of the cyclone separator 20 is conical, and the lower port of the cone is communicated with the return port 13 through the return pipe 19. The water vapor in the nitridation reaction product and the powder in the waste gas enter the cyclone separator 20 together. The water vapor condenses into water droplets and mixes with the powder, and automatically agglomerates into small particles in the conical space at the lower part of the cyclone separator 20. The agglomerated small particles enter the boiling chamber 14 through the return pipe 19 for re-calcination. Therefore, there is less powder in the waste gas, the reaction is complete, the waste gas is easy to treat, the gas-solid reaction efficiency is high, and the raw material utilization rate can be significantly improved.

[0067] (6) Clean and environmentally friendly, and high calcination capacity. The ammonia gas "blown in" by the blower in this specific embodiment serves as both a reducing agent and a nitriding agent for the preparation of vanadium nitride alloy. No additional carbon powder reducing agent is required during the calcination process, and there is no CO in the calcination process 2, gases such as CO are generated, and the reaction products are mainly vanadium nitride and water vapor, which is clean and environmentally friendly. The roasted vanadium nitride (vanadium-nitrogen alloy) has a high N content and is clean and environmentally friendly.

[0068] Therefore, this specific embodiment has the characteristics of simple structure, convenient operation, low energy consumption, high raw material utilization rate, and automatic discharging. This roasting furnace is suitable for ammonia roasting, with high efficiency in preparing vanadium-nitrogen alloy and good product quality.

Claims

1. A medium-temperature roasting furnace for vanadium-nitrogen alloy, characterized in that the furnace body (9) of the medium-temperature roasting furnace for vanadium-nitrogen alloy is a hollow square column composed of an outer wall, a furnace bottom and a furnace top. An inner wall is coaxially arranged inside the outer wall. The cross-sections of both the outer wall and the inner wall are rectangles. The distance between the inner wall and the outer wall of the furnace body (9) is equal, and a "return" shaped space is formed between the inner wall and the outer wall of the furnace body (9); at the bottom of the furnace body (9), a first ammonia buffer chamber (6), a second ammonia buffer chamber (5), a third ammonia buffer chamber (16) and a discharge chute (17) are successively arranged from left to right. The outlets of a first blower (3), a second blower (2) and a third blower (1) are communicated with the bottoms of the corresponding first ammonia buffer chamber (6), second ammonia buffer chamber (5) and third ammonia buffer chamber (16) through their respective air ducts, and the inlets of the first blower (3), second blower (2) and third blower (1) are communicated with an ammonia gas source; the tops of the first ammonia buffer chamber (6), the second ammonia buffer chamber (5) and the third ammonia buffer chamber (16) are the same inclined plane, and the inclined plane is an inclined plane with the left side higher than the right side. The included angle α between the inclined plane and the vertical plane is 95° - 110°; the space from the inclined plane to the top of the furnace body (9) is a boiling chamber (14), and the inclined plane is also the bottom of the boiling chamber (14); air caps (15) are evenly arranged on the inclined plane. The first ammonia buffer chamber (6), the second ammonia buffer chamber (5) and the third ammonia buffer chamber (16) are communicated with the boiling chamber (14) through the air caps (15) arranged on their respective tops; the discharge chute (17) is surrounded by the front inner wall, the rear inner wall, the left inner wall of the furnace body (9) and the right side wall of the third ammonia buffer chamber (16). An outlet (18) is arranged at the middle position of the bottom of the discharge chute (17), and a valve is arranged at the end of the outlet (18); discharge plates are symmetrically arranged on the front and rear sides of the outlet (18). The upper ends of the two discharge plates are symmetrically close to the inner walls on their respective same sides, and the upper ends of the two discharge plates are respectively flush with the right side of the inclined plane; the lower ends of the two discharge plates are symmetrically located beside the outlet (18), and the width of the two discharge plates is equal to the width of the discharge chute (17); a cyclone separator inlet (11) is arranged at the top of the rear side wall of the furnace body (9), and the cyclone separator inlet (11) is directly above the third ammonia buffer chamber (16); a return port (13) is arranged in the middle of the rear side wall of the furnace body (9), and a feed pipe (8) is arranged at the upper middle part of the left side wall of the furnace body (9). The upper end of the feed pipe (8) is externally connected to a feeding device, and the feed inlet of the feed pipe (8) is communicated with a distributor (12). The distributor (12) is horizontally arranged close to the left inner wall. The height of the distributor (12) from the furnace bottom is 0.5 - 0.7 times the height of the furnace body (9), and the height of the return port (13) is the same as that of the distributor (12); The inlet (11) of the cyclone separator is connected to the cyclone separator (20) through a channel. A cyclone separator outlet (10) is provided at the middle position of the top of the cyclone separator (20), and the cyclone separator outlet (10) is connected to an external waste gas treatment system; the lower part of the cyclone separator (20) is conical, and the lower port of the cone communicates with the return port (13) through a return pipe (19); the angle β between the return pipe (19) and the horizontal plane is 10° to 30°; A preheating electric heating wire group (4) and a heating electric heating wire group (7) are sequentially arranged upward from the bottom of the "return" - shaped space; the preheating electric heating wire group (4) is at the same height as the adjacent first ammonia buffer chamber (6), the height of the preheating electric heating wire group (4) is 0.2 to 0.25 times the height of the furnace body (9), and the preheating electric heating wire group (4) heats the first ammonia buffer chamber (6), the second ammonia buffer chamber (5) and the third ammonia buffer chamber (16); the height of the heating electric heating wire group (7) is the same as the height of the preheating electric heating wire group (4), and the heating electric heating wire group (7) heats the boiling chamber (14); The length of the boiling chamber (14) is 10 to 20 m, and the width of the boiling chamber (14) is 0.5 to 0.65 times the length of the boiling chamber (14); The width of the first ammonia buffer chamber (6) is 13 to 15% of the length of the boiling chamber (14), the width of the discharge chute (17) is 2 to 5% of the length of the boiling chamber (14), and the widths of the second ammonia buffer chamber (5) and the third ammonia buffer chamber (16) are each half of the remaining length of the boiling chamber (14).

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