CN115772624A - Method for producing vanadium-nitrogen alloy - Google Patents

Abstract

A method for producing vanadium-nitrogen alloy comprises the steps of mixing vanadium oxide and a carbonaceous reducing agent, carrying out compression molding, and carrying out high-temperature reaction in a direct-heating rotary kiln to obtain a vanadium-nitrogen alloy product. The repose angle of the material pile of the pressed and molded material ball is less than 25 degrees. The two ends of the heating section of the kiln chamber of the direct heating type rotary kiln are provided with positive and negative electrodes, the pellet stacks are electrified through the electrodes, and the pellet stacks are heated by using the self resistance heating of the pellet stacks. The invention has the advantages of improving the fluidity of the material balls, simplifying the coordination control among the rotating speed of the rotary tube of the rotary kiln, the inclination rate of the rotary tube, the material filling rate and the height of the baffle plate or the baffle ring, improving the filling rate of the materials in the kiln chamber, reducing the voltage of a heating power supply, reducing the powder quantity and the dust flying in the kiln chamber, improving the productivity of equipment and reducing the energy consumption.

Description

A kind of method of producing vanadium nitrogen alloy

technical field

The invention relates to a method for preparing a vanadium-nitrogen alloy by high-temperature carbothermal reduction and nitriding, and belongs to the technical field of metallurgical charge.

Background technique

Vanadium-nitrogen alloy is a kind of steelmaking charge. The current national standard for vanadium-nitrogen alloy has requirements on the particle size of vanadium-nitrogen alloy products. It is required that the particles with a particle size below 10mm in the product should not exceed 5% of the total.

Rotary kiln is an important heating and calcination equipment in the chemical industry, materials, and even pharmaceutical industries, and it is widely used. The Chinese patent CN112880389A submitted by the inventor discloses a direct-heating rotary kiln for carbothermal reduction and nitriding reaction, which is a kind of heated solid material (that is, rotary kiln) that directly feeds power into the rotary kiln through electrodes. The material processed by the kiln, hereinafter referred to as the material), the current flows from the heating power supply through the positive electrode through the material, returns to the negative electrode and then returns to the heating power supply, and uses the resistance of the material to make the material itself directly heat the electric heating rotary kiln (hereinafter referred to as the direct heating rotary kiln. kiln). The material in the kiln chamber (the approximately cylindrical inner cavity formed by the refractory material close to the inner wall of the rotary tube, that is, the place where the material in the rotary tube can reach) generally rotates and/or rolls with the rotation of the rotary tube, and due to the rotary The rotary tube of the kiln generally has an inclination angle with the horizontal plane, and the material will also advance axially along the rotary tube during the rotation process, that is, the material in the rotary kiln advances in a spiral. The feed end of the kiln chamber is sealed and connected with the kiln head box, and the discharge end of the kiln chamber is sealed and connected with the kiln tail box. The kiln chamber of the rotary kiln is divided into a preheating section (or heating section), a heating section (or high temperature section), and a cooling section (or cooling section) along the axial direction of the rotary tube. The materials pass through the preheating section, heating section, and cooling section in sequence. Then, it falls from the kiln chamber discharge port into the kiln tail box for temporary storage, and then intermittently withdraws from the kiln tail box. Generally speaking, during the production process of the rotary kiln, the distance between the positive and negative electrodes inside the rotary tube has been fixed, and the length of the material in the heating section that is used as a heating resistor is further fixed. The cross-sectional area of the material in the heating section will increase with the increase of the filling rate of the material in the kiln chamber (the filling rate of the rotary kiln is generally defined as the ratio of the volume of the material in the rotary kiln to the volume of the kiln chamber of the rotary kiln). The filling rate of the kiln, or increasing the filling rate of the heating section, can increase the production capacity of the direct-heating rotary kiln (that is, the output per unit time).

The general non-direct heating rotary kiln is affected by the heat transfer limitation, and its material filling rate, especially the filling rate of the heating section, is rarely greater than 20%. As a direct-heating rotary kiln, the material in the kiln chamber generates heat directly, which saves the process of heat transfer from the inner wall of the rotary tube or the atmosphere in the kiln chamber to the material, and can increase the material filling rate in the heating section while maintaining the increase in the material flow rate. The production capacity of the rotary kiln reduces the energy consumption per unit of product (because regardless of the production capacity, as long as the temperature is the same, the amount of heat dissipation from the same rotary kiln to the surrounding environment through the rotary tube is basically constant. If the production capacity is large, the heat loss shared by the unit product is equal to Small), of course, also improves production efficiency. Generally, during the operation of the direct-heating rotary kiln, the filling rate is controlled above 25%, preferably around 50%. For materials with good fluidity and no serious caking, it can be controlled at 70% or even higher, improving the The production capacity of the equipment is at least doubled.

In the process of using vanadium oxy compound and carbonaceous reducing agent as raw materials to produce vanadium nitrogen alloy, a large amount of oxygen and carbon in the solid raw material will generate carbon monoxide gas and be discharged during the reaction process. Large, the volume is reduced to about 25% of the original material ball. When the direct-heating rotary kiln is used as the reactor for the carbon thermal reduction reaction, after the installation of the rotary kiln is completed, the structure of the kiln chamber, that is, the kiln type, is also fixed immediately, and the length of the kiln chamber and the inclination rate of the rotary tube (rotary tube axis and The included angle of the horizontal plane) is also fixed, and its influence on the advancing speed of the material in it is also fixed. The volumetric flow rate of the unreduced material (hereinafter referred to as the material at the left end) and the material with a partially or completely reduced volume (hereinafter referred to as the material at the right end) is not much different, and the speed control step of the material flow rate must be the volumetric flow rate of the material at the left end. That is, even if the volume flow rate of the material at the left end is greater than that of the material at the right end, as long as it does not exceed three times, the volume flow rate of the material at the left end cannot meet the volume flow rate of the material at the right end. reduce. In actual production practice, due to the high-temperature contraction and longer-time movement of the above-mentioned right-end material in the rotary kiln, it is smoother and denser than the left-end material, which is more conducive to increasing its volume flow rate. Even if the inclination rate of the rotary tube is increased during the manufacture and installation of the rotary kiln, due to the increase in the inclination rate, the inclination rate of the material at the right end will also increase at the same time, so it still cannot solve the problem that the volume flow rate of the material at the left end cannot keep up with the volume flow rate of the material at the right end. The problem.

In addition, in the process of producing vanadium-nitrogen alloys in the direct-heating rotary kiln, the temperature in the heating section is relatively high, generally above 1200°C, and the volatile components at high temperature will flow to the preheating section with the gas phase. The formation of loops in a certain section of the preheating section is a common phenomenon of loop formation in rotary kilns, and the formation of loops will further reduce the volume flow rate of the material at the left end.

Therefore, the flow velocity of the material at the left end becomes a restrictive control factor hindering the filling rate of the material in the kiln chamber, especially the filling rate of the heating section, and is a flow velocity bottleneck. This greatly reduces the material filling rate of the direct-heating rotary kiln, limits the length of the preheating section of the rotary kiln (the longer the preheating section, the greater the resistance to the material volume flow rate), reduces its equipment capacity, and increases the material volume. Fill rate difficulty. Although the inventor adopted a variety of technical solutions in the CN112880389A patent application to improve the filling rate of the material in the heating section and the advancing speed of the material at the left end in the direct-heating rotary kiln, it also encountered control difficulties, and it was difficult to balance the flow rate of the material and the filling rate. It is necessary to study and adjust various structural parameters of the direct heating rotary kiln for different materials and materials with different volume shrinkage ratios. Especially when the inner diameter and length of the kiln chamber become larger, it is difficult to adjust the structural parameters of the rotary kiln and the rotational speed of the rotary tube to a level that makes the material filling rate in the kiln chamber relatively high, and at the same time take into account the discharge speed. This makes it very difficult to expand the production capacity of vanadium-nitrogen alloys with larger rotary kilns.

There is also a patent application to propose the technical scheme of promoting the left end material at the feed port end of the kiln chamber with a push rod. However, due to the limitation of the operating temperature, the reliability limitation of the push rod itself, the limited pushing effect of the push rod, and the breaking of the raw material ball caused by the push rod, it has not been able to solve the above-mentioned bottleneck problem of flow rate well.

The existing vanadium-nitrogen alloy mainstream production process uses a pusher kiln as the equipment for the carbothermal reduction and nitriding reaction. The raw material balls are loaded into the graphite crucible and pushed into the pusher kiln intermittently, which affects the fluidity or motion dynamics of the raw material balls. There is no requirement, so the production process of vanadium-nitrogen alloy is consistent with the use of the double-roller ball press machine used in this process to press the ball into the raw material. The commonly used roller briquetting machine has large production capacity, high degree of automation, simple operation and low equipment price, and is widely used. However, due to the difficulty of demoulding, the depth of the hemispherical socket on the roller mold or the ratio of the depth of the hemispherical socket to the opening width is limited. If the ball socket is too deep, it is difficult to demould, and the opening surface of the hemispherical socket is square. Or a rounded square shape with chamfered corners. Therefore, the depth of the general ball socket is made relatively shallow, and the roundness of the extruded ball is very poor, even close to the shape of a round cake or a double quadrangular pyramid. The angle of repose of the pile of material balls of this shape is relatively large, it is difficult to flow in the rotary kiln, and the forward speed is low.

In summary, although the direct-heating rotary kiln has great advantages in the production of vanadium-nitrogen alloys by carbothermal reduction and nitriding reaction, only the improvement of the direct-heating rotary kiln can increase the filling rate of materials in the kiln chamber, and It is very difficult to increase the volume flow rate of materials at the same time, and it is necessary to seek improvements in processes other than the direct-heating rotary kiln to achieve the purpose of increasing the filling rate and increasing the volume flow rate of materials.

Contents of the invention

Purpose of the invention: In the production process of vanadium-nitrogen alloy in the direct-heating rotary kiln process, under the high-temperature reaction operation state of the material in the kiln chamber, the volume flow rate of the aforementioned left end material in the kiln chamber can be increased so that it can reach the fully shrunk right end The volume flow rate of the material is more than three times that of the material volume flow rate at the left end, eliminating the restriction on the filling rate of the kiln chamber; improving the fluidity of the solid material, taking into account a sufficiently high filling rate of the solid material in the kiln chamber, reducing the rotation speed of the rotary tube during operation, and reducing the kiln filling rate. The difficulty of adjusting the relationship between speed and output. Through the above objectives, the purpose of further improving the electrothermal efficiency of the direct-heating rotary kiln, simplifying the structural adjustment of the rotary kiln equipment, reducing the difficulty of controlling the operation of the rotary kiln, improving the stability of the rotary kiln operation, increasing the production capacity of the equipment, and reducing the amount of dust generated is achieved.

The purpose of the present invention is achieved in that the present invention is on the basis of summing up the inventor's previous manufacture and use of the direct-heating type rotary kiln to carry out vanadium-nitrogen alloy production experience, improves the pressure ball technology of raw material in the vanadium-nitrogen alloy production, improves The roundness of the formed raw material ball reduces the difficulty of adjusting various structural parameters of the direct heating rotary kiln and improves its operation stability.

Concrete technical scheme of the present invention is as follows:

A method for producing a vanadium-nitrogen alloy, the process of which is to mix a vanadium oxide compound and a carbonaceous reducing agent, press and form it with a briquette machine, and then react at a high temperature in a direct-heating rotary kiln to obtain a vanadium-nitrogen alloy product. The vanadium oxy compound is generally one or more of vanadium oxide, ammonium metavanadate, ammonium polyvanadate or red vanadium in various valence states. The carbonaceous reducing agent is generally one or more of graphite powder, calcined coke or organic polymer. The present invention is characterized in that: the angle of repose of the pile formed by the press-molded pellets is less than 25°.

The direct heating rotary kiln includes a rotary tube, refractory material inside the rotary tube, kiln head box and kiln tail box; the elongated inner cavity surrounded by the refractory material is the kiln chamber; the kiln chamber is divided into a preheating section, Heating section and cooling section: Positive and negative electrodes are set at both ends of the heating section, and the heating power supply is externally connected to the heating power supply on the positive and negative electrodes. The electrodes are in contact with the heated material inside the rotary kiln, and the current flows through the material through the positive electrode and then to the negative electrode. , so that the material itself heats up as a resistance to complete the heating of the material; a protrusion with a height of more than 1cm is provided on the inner wall of the kiln chamber to form a frying tank or a material retaining ring, or to form a frying tank and a material retaining ring ; Rotating and sealing connection between the rotary pipe and the kiln head box and the kiln tail box; an air inlet is arranged on the kiln tail box.

The material balls enter the kiln chamber through the kiln head box of the direct heating rotary kiln, pass through the preheating section, heating section and cooling section in turn, and then drop from the kiln chamber discharge port into the kiln tail box for temporary storage. out of the kiln tail box; the pellets are heated to above 1200°C in the heating section.

There is an air inlet on the kiln tail box, through which nitrogen gas enters the kiln tail box, passes through the kiln cooling section, heating section and preheating section in turn, and then withdraws from the kiln chamber.

Further, the ball briquetting machine is a double-roller briquetting machine, which has two rollers with opposite rotation directions installed side by side in the horizontal direction, and a hemispherical socket mold is arranged on the outer peripheral surface of each roller. A plurality of hemispherical socket molds are arranged on the hemispherical socket mold, and part or all of the shape of the hemispherical socket is made of elastic material.

Further, the elastic material is rubber.

Further, the rubber is polyurethane rubber. The rubber material at the bottom of the hemispherical socket is relatively thick. When the ball is pressed, the rubber at the thicker part moves to the thinner part under the pressure, which increases the depth of the hemispherical socket, and thus the roundness of the pressed material ball is higher. As the two rollers rotate downward at the extrusion ball, the pressure on the hemispherical socket decreases and disappears, the rubber material rebounds, and the rebound deformation and elastic force make the formed ball fall off the mold. For rubber molds or molds made of partial rubber material, the balls are pressed and formed, and the angle of repose of the static pile is less than 15°.

The described ball briquetting machine is a double-roller briquetting machine, and the mold liquid on the rolls of the ball briquetting machine can be a rigid material mold or a steel mould. A plurality of hemispherical socket molds are arranged on the steel hemispherical socket mold, and the opening surfaces of the hemispherical socket molds are hexagonal or rounded hexagonal with chamfered corners. The material ball formed by such a mold has an angle of repose of the static material pile less than 25°.

Compared with the above two ball briquetting processes, the opening of the hemispherical socket of the roll mold of the double-roll briquetting machine used in the existing vanadium-nitrogen alloy production line is quadrilateral or rounded quadrilateral, and the entire mold is made of steel rigid material. The pressed pellets are approximately twelve-edged octahedron structure, only the edges and corners are chamfered. Such balls have very poor fluidity, and the angle of repose is ~35°, which is close to the angle of repose of most powder materials.

Further, a baffle plate is arranged at the discharge port of the kiln chamber; the balls passing through the cooling section of the kiln chamber pass through the material baffle plate from the discharge port of the kiln chamber and drop into the kiln tail box for temporary storage. In the case of improving the roundness of the balls and reducing the angle of repose of the ball pile when static, even the volume flow rate of the material at the left end is higher than the requirements of the material filling rate and the maximum production capacity of the rotary kiln. In this way, a material baffle plate is set at the discharge port of the kiln chamber, or a material retaining ring is arranged at the cooling section of the kiln chamber to reduce the volume flow rate of the material ball at this place, making it a control bottleneck of the kiln chamber discharge speed. After these improvements, the output of vanadium-nitrogen alloy in the rotary kiln is almost linearly positively correlated with the rotational speed of the rotary tube. Even when the maximum production capacity of the rotary kiln is reached, the filling rate of the material in the kiln can be kept sufficiently large.

Further, iron oxide and/or iron powder are added to the vanadium oxide compound and carbonaceous reducing agent raw materials, and the amount of added iron element does not exceed 120% of the amount of vanadium element, so as to prepare iron-containing vanadium-nitrogen alloy or nitrided Ferrovanadium.

Compared with prior art, adopt the present invention to have following advantage:

1) By pressing the raw materials into balls with better roundness, in the high-temperature carbothermal reduction reaction for the production of vanadium-nitrogen alloys, even if the volume of the materials is greatly reduced during the reaction process, it improves the temperature of the raw material balls under direct heat. The volume flow rate in the kiln chamber of the type rotary kiln makes the volume flow rate of the aforementioned left end material keep up with the needs of the right end material volume flow rate. The filling rate of the material in the kiln chamber is improved, and the rotary tube can be operated at a lower speed.

2) Due to the improvement of the roundness of the raw material balls, in the case of ring formation in the kiln preheating section, the raw material balls can also maintain a sufficient volume flow rate at the ring formation to meet the aforementioned requirements for the volume flow rate of the material at the right end. The operation stability of the rotary kiln is maintained, and the maintenance interval of the rotary kiln thus caused is prolonged.

3) Due to the improvement of the roundness of the raw material ball, the volume flow rate of the material at the left end is increased, so that the bottleneck of the volume flow rate of the overall material is moved to the stop ring or the stop plate, thus simplifying the control of the filling rate of the material in the kiln chamber , Simplified the corresponding relationship between the rotational speed of the rotary tube and the volume flow rate of the solid material at the outlet of the kiln chamber. In the case that the heating capacity is sufficient and the minimum reaction time requirement is maintained, the output of the rotary kiln can be directly controlled by the rotation speed of the rotary tube.

4) Due to the improvement of the roundness of the raw material ball, the rotary tube can also provide a sufficient volume flow rate of the solid material at a relatively low speed, thereby reducing the degree of wear of the material, reducing the generation of dust and dust in the kiln chamber, and reducing Reduced the pressure of dust recovery and dust control.

5) Due to the improvement of the roundness of the raw material ball, the volume flow rate of the material at the left end is increased. The longer length of the preheating section of the kiln chamber has little effect on the volume flow rate of the material at the left end. A longer length of the preheating section can be set to improve The heat exchange effect of the preheating section reduces the temperature of the gas withdrawn from the preheating section, increases the temperature of the solid material entering the heating section from the preheating section, and increases the pre-reduction degree of the solid material entering the heating section.

6) Due to the improvement of the roundness of the raw material ball, the volume flow rate of the material at the left end can be increased, the inclination rate of the rotary tube can be reduced, and the operating safety and life of the rotary kiln can be improved.

7) Due to the improvement of the roundness of the raw material balls, the edges and corners of the balls are reduced, the wear rate of the edges and corners of the raw material balls in the kiln chamber is reduced, the proportion of fine-grained materials is reduced, and the return of fine-grained materials is reduced. Ratio, improve production efficiency.

8) Due to the improvement of the roundness of the raw material ball, it is relatively simple to adjust the structural parameters of the rotary kiln, the filling rate of the kiln material, the rotational speed of the rotary tube, and the speed of feeding and discharging materials, making it possible to manufacture larger-scale direct-heating rotary kilns and expand production Scale, technically becomes relatively simple.

Adopting the technical solution of the present invention to carry out the vanadium-nitrogen alloy, the production is stable and reliable, the output of the carbothermal reduction reaction is improved, the process is environmentally friendly, efficient, energy-saving, highly automated, and the production cost and labor intensity are reduced.

Description of drawings

Fig. 1 is a schematic diagram of a direct-heating rotary kiln in Embodiment 1.

Fig. 2 is a schematic front view of the rotary tube of the direct-heating rotary kiln in Embodiment 1 from the discharge end to the feed end, and the upper left part is partially cut away.

Fig. 3 is a schematic diagram of a hemispherical socket mold of a pair of rolling ball presses in embodiment 1.

Fig. 4 is a schematic diagram of the hemispherical socket moulds of the pair of roller briquetting machines in embodiment 2.

Example 1

Fig. 1 and Fig. 2 are the schematic diagrams of embodiment 1. As shown in Figure 1, the direct heating type rotary kiln is used as a reactor for carbothermal reduction and/or nitriding reaction of raw materials such as metal oxides, including a kiln head box 1, a kiln head box exhaust gas outlet 16, a drive Wheel 2, load-bearing wheel 3, a set of two positive poles 14, a rotary tube 5, refractory material 6, a set of two negative poles 15, 6 k-degree thermocouples 12, the rotary and sealed connection between the kiln tail box and the rotary tube 8. The kiln tail box 9 and the air inlet 13 on the kiln tail box. The refractory material 6 plays the role of fire resistance, heat preservation and insulation at the same time, and it is required that the resistance of the refractory material in contact with the material in the heating section is greater than that of the material. An approximately circular cavity surrounded by the refractory material 6 and approximately equal in length to the rotary tube is called the kiln chamber 17 . The kiln chamber 17 is successively divided into a kiln chamber feed inlet 171 , a preheating section 172 , a heating section 173 , a cooling section 174 and a kiln chamber outlet 175 according to the sequence in which materials pass through. The rest of the details are not shown.

As shown in Figure 2, the refractory material 6 of the direct heating rotary kiln consists of refractory materials 602 and 601 of two specifications, high and low. In the radial direction of the rotary tube, the refractory material 602 protrudes more than 601 in the kiln chamber, and the protruding height is 3 cm, forming a frying tank. When the rotary kiln is rotating, it can prevent the material from sliding on the wall of the kiln chamber and raise the level of the material. A baffle plate 19 is set at the discharge port of the kiln chamber, or a section of sieve pipe 25 is connected at the discharge port of the kiln chamber, and a baffle plate 19 is set at the discharge port of the sieve pipe. The included angle between the upper right edge of the baffle plate 19 in FIG. 2 and the horizontal plane is set to 20°. It can also be seen from Figure 2 that the ring-shaped negative electrode 15 is higher than the surrounding refractory materials 601 and 602 in the direction facing the central axis of the rotary tube, forming a retaining ring.

Figure 3 is a schematic cross-sectional view of the hemispherical socket mold of the roller briquetting machine. Sub-figure B is a partially enlarged view of sub-figure A. The roll steel mold 1 of the ball briquetting machine is a ring structure, and a series of hemispherical sockets are regularly arranged on the outer cylindrical surface. The shaft that drives the rotation of the steel mold fits into its inner circle. A mold 2 of polyurethane rubber material is arranged in the hemispherical socket. The mold 2 covers the bottom of the hemispherical socket of the steel mold 1 and constitutes a part of the hemispherical socket mould. A pair-roller briquetting machine has two rolls, each of which has a steel mold 1 whose rotation axes are arranged side by side in parallel on the horizontal plane, whose cylindrical surfaces are separated from each other by 1 to several millimeters, and a steel mold with a hemispherical socket Align the hemispherical socket of another steel mold. Two opposing hemispherical fossae form an approximate spherical shape. The two hemispherical sockets that are going to be facing each other will gouge the solid material above them into the hemispherical sockets with the downward rotation of the counter rollers, and the extrusion process will be completed when the two hemispherical sockets are facing each other. At this time, the rubber at the thicker part of the rubber at the bottom of the hemispherical socket will expand to the thinner parts around, making the bottom of the ball socket deeper, and making the solid material surrounded by the two ball sockets more spherical. As the pair of rollers continue to rotate downward, the pressure gradually disappears, and the rubber rebounds and ejects the ball, completing the ball pressing process.

Use vanadium pentoxide, carbon powder and iron oxide powder as raw materials, mix according to the mass ratio of 100:28.5:0.3, add 15~25% water (based on vanadium pentoxide), stir and roll it , The raw material balls obtained by pressing with the above-mentioned double-roller ball pressing machine are close to spherical, with good roundness. The long diameter of a single raw material ball is ~4.0cm, and the short diameter is ~3.5cm. The angle of repose of the raw material ball pile is less than 15°. The wall of the kiln has a stir-frying trough with a depth of ~3cm formed by protruding refractory materials. When the rotary tube rotates at a speed of 0.2 rpm, the angle between the slope of the raw material balls in the kiln and the horizontal plane is less than 20° (measurement comparison Difficult, the accuracy is not high, the same below). The pellets are used to produce vanadium-nitrogen alloys in a direct-heating rotary kiln with a length of 16m and an effective inner diameter of the kiln chamber of 58cm. It is found that the material filling rate in the heating section can be easily controlled to about 50%. The inclination rate of the rotary tube can be reduced (from 4.0%) to 2.0% (the value expressed as a percentage of the tangent of the angle between the rotary axis of the rotary tube and the horizontal plane), and the fine particles in the discharge that do not meet the national standard of vanadium nitrogen alloy can be reduced from about 5%. reduced to about 2%.

As a comparison, the raw material balls pressed by the existing pair of roller briquetting machines are approximately double quadrangular pyramids in which two quadrangular pyramids with a square bottom are buckled together on one side of the square. The angle of repose of the raw material ball is about 35°. When using such balls to enter the direct-heating rotary kiln to produce vanadium-nitrogen alloys, the inclination rate of the rotary tube needs to be set to 4.0%, and the angle between the upper right edge of the kiln outlet baffle plate 19 in Figure 2 and the horizontal plane needs to be Set to 40°. Under the condition that other rotary kiln structures and process parameters are the same as those of the aforementioned rotary kiln in this example, the angle between the inclined plane of the stockpile and the horizontal plane is >40°. In fact, within a relatively large range of structural parameters of the rotary kiln, under high-temperature reaction conditions, the volume flow rate of the material at the left end cannot keep up with the volume flow rate of the material at the right end, resulting in a decrease in the filling rate of the heating section and cooling section of the kiln chamber, and the volume flow rate of the material at the left end becomes Limiting factors for kiln filling rate and capacity increase of rotary kiln.

Example 2

Figure 4 is a schematic cross-sectional view of the roll hemispherical socket mold of the double-roll ball pressing machine. Sub-figure B is a partially enlarged schematic diagram of sub-figure A, and sub-figure c is an enlarged schematic diagram of the opening surface of the hemispherical fossa. The roll steel mold 1 of the ball briquetting machine is a ring structure, and a series of hemispherical dimples 2 are regularly arranged on the outer cylindrical surface. The shaft that drives the rotation of the steel mold fits into its inner circle. The opening surface of the hemispherical socket is approximately hexagonal or rounded hexagonal. The edges inside the hemispherical socket are chamfered. The long diameter of the pressed material ball is about 3.6cm, and the short diameter is about 3.0cm. For the pellets pressed in this embodiment, the static angle of repose of the pile is 20-25°.

Using the same direct-heating rotary kiln as in Example 1, the inclination rate of the rotary tube can be reduced (from 4.0%) to 3.0%, and the angle between the inclined plane of the raw material ball in the kiln chamber and the horizontal plane is about 25°. The material filling rate in the heating section can be controlled to about 50%. The fine material that does not meet the national standard of vanadium-nitrogen alloy in the output is reduced from about 5% to about 3%.

Claims (9)

1. A method for producing vanadium-nitrogen alloy, its process is to mix vanadium oxide compound and carbonaceous reductant, briquetting machine compression molding, then obtain vanadium-nitrogen alloy product through high-temperature reaction in direct-heating type rotary kiln, its characteristic In that: the angle of repose of the static stockpile formed by the press-molded pellets is less than 25°; The direct heating rotary kiln includes a rotary tube, refractory material inside the rotary tube, kiln head box and kiln tail box; the elongated inner cavity surrounded by the refractory material is the kiln chamber; the kiln chamber is divided into a preheating section, Heating section and cooling section: Positive and negative electrodes are set at both ends of the heating section, and the heating power supply is externally connected to the heating power supply on the positive and negative electrodes. The electrodes are in contact with the heated material inside the rotary kiln, and the current flows through the material through the positive electrode and then to the negative electrode. , so that the material itself heats up as a resistance to complete the heating of the material; a protrusion with a height of more than 1cm is provided on the inner wall of the kiln chamber to form a frying tank or a material retaining ring, or to form a frying tank and a material retaining ring ; Rotating and sealed connection between the rotary pipe and the kiln head box and the kiln tail box; an air inlet is arranged on the kiln tail box; The material balls enter the kiln chamber through the kiln head box of the direct heating rotary kiln, pass through the preheating section, heating section and cooling section in turn, and then drop from the kiln chamber discharge port into the kiln tail box; The section is heated above 1200°C; There is an air inlet on the kiln tail box, through which nitrogen gas enters the kiln tail box, passes through the kiln cooling section, heating section and preheating section in turn, and then withdraws from the kiln chamber. 2. a kind of method for producing vanadium-nitrogen alloy according to claim 1, it is characterized in that: described briquetting machine is a pair of roll briquetting machine, and it has the opposite roll of two rotation directions that horizontal direction is oppositely installed, A hemispherical socket mold is arranged on the outer circumference of each roll, and part or all of the hemispherical socket shape of the hemispherical socket mold is made of elastic material. 3. A method for producing vanadium-nitrogen alloy according to claim 2, characterized in that: said elastic material is rubber. 4. A method for producing vanadium-nitrogen alloy according to claim 3, characterized in that: said rubber is polyurethane rubber. 5. a kind of method for producing vanadium-nitrogen alloy according to claim 1, is characterized in that: described briquetting machine is a pair of roll briquetting machine, and it has the opposite roll of two rotation directions that horizontal direction is oppositely installed, A hemispherical socket mold is arranged on the outer circumference of each roll, and the hemispherical socket opening surface of the hemispherical socket mold is hexagonal or hexagonal with chamfered corners. 6. A method for producing vanadium-nitrogen alloy according to any one of claims 1 to 5, characterized in that: a baffle plate is arranged at the outlet of the kiln chamber; the material passing through the cooling section of the kiln chamber The balls pass through the baffle plate from the discharge port of the kiln chamber and fall into the kiln tail box for temporary storage. 7. A method for producing vanadium-nitrogen alloy according to any one of claims 1 to 5, characterized in that: the heating power supply is an adjustable DC power supply, the maximum output voltage of which is Umax volts, and the maximum output current Imax ampere; have a voltage value U1 between 0 ~ Umax volts, and have a current value I1 between 0 ~ Imax ampere; when the direct heating type rotary kiln is working, the heating power supply is on the premise of keeping the installed power constant In this mode, its output can be switched between two voltage and current ranges; the two voltage and current ranges are high voltage and low current and low voltage and high current respectively; in the high voltage and low current range, the output voltage can be adjusted from 0 to Umax volts, the adjustable range of output current is 0 ~ I1 amperes; in low voltage and high current mode, the adjustable range of output voltage is 0 ~ U1 volts, and the adjustable range of output current is 0 ~ Imax amperes. 8. A method for producing vanadium-nitrogen alloy according to any one of claims 1 to 5, characterized in that: there are one or more thermocouples in the kiln heating section, which are arranged along the radial direction of the rotary tube. The direction passes through the rotary tube and is inserted into the refractory material or passes through the refractory material and is close to the wall of the kiln chamber; the temperature data analog value measured by the thermocouple is converted by a temperature transmitter fixed on the outer surface of the rotary tube for analog-to-digital conversion Wireless transmission to the control cabinet of the heating power supply is used for displaying the temperature and controlling the output power of the heating power supply. 9. according to a kind of method for producing vanadium-nitrogen alloy described in any one in claim 1～5, it is characterized in that: iron oxide and/or iron powder are added in vanadium oxide compound and carbonaceous reductant raw material, added The amount of iron element does not exceed 120% of the amount of vanadium element, and an iron-containing vanadium-nitrogen alloy or ferrovanadium nitride is prepared.

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