A mixing device and method for improving tungsten carbide combined carbon

Abstract

The present application relates to the technical field of hard alloy powder preparation, and provides a mixing device and method for improving tungsten carbide carbonization, which comprises a bin body structure, a shell and a bin cover form a closed mixing chamber, the shell has a temperature regulating hollow partition; a mixing mechanism, comprising a driving shaft and a spiral belt with a triangular notch; a flying knife mechanism located on the spiral belt throwing path, comprising a knife shaft, a hinged cutter and an angle adjusting assembly. The present application effectively solves the problem of low combined carbon caused by uneven mixing in the production of superfine tungsten carbide through the synergistic effect of high-frequency shearing of the flying knife and low-speed diffusion of the spiral belt, and realizes the high uniformity mixing of tungsten powder and carbon black.

Description

Technical Field

[0001] This invention relates to the field of cemented carbide powder preparation technology, and more specifically, to a mixing apparatus and method for improving the carbon content of tungsten carbide. Background Technology

[0002] Tungsten carbide (WC) is the most important raw material for cemented carbide, with a theoretical carbon content of 6.128% (atomic ratio 1:1) based on its stoichiometric ratio. In cemented carbide production, the combined carbon content of tungsten carbide is typically required to be 6.07%, with free carbon ≤0.05%. When the combined carbon content is too low (<6.08%), a carbon-deficient η-phase (W2C or M6C type carbides) will form, leading to increased brittleness and decreased wear resistance in the cemented carbide. When free carbon is present (>0.05%), it will promote abnormal grain growth of WC during sintering, resulting in uneven alloy grains and reduced mechanical properties. Ultrafine tungsten carbide (particle size <0.5μm) is prone to agglomeration and the formation of pseudo-particles during the mixing process due to its large specific surface area and high surface energy. Traditional ball mill dry mixing has limited uniformity, is prone to localized carbon segregation, producing W2C and free carbon impurities. Furthermore, wear of the steel balls / cylinder introduces Fe impurities, contaminating the WC powder. It also suffers from high noise and energy consumption, cumbersome cleaning during production changes, and large fluctuations in carbon content, making it unsuitable for submicron / nano WC. V-type / double-cone mixers have low mixing intensity and weak dispersion ability for ultrafine tungsten powder. Their carbon uniformity is inferior to high-energy mixers, and localized carbon unevenness may still exist after carbonization, requiring extended carbonization time.

[0003] More importantly, the carbonization reaction (W+C→WC) involves solid-state diffusion and a methane intermediate mechanism (CH4 decomposes carbon). The uniformity of carbon atom distribution on the surface of tungsten powder particles directly determines the completeness of the carbonization reaction. If the tungsten powder and carbon black are not mixed uniformly, excessively low carbon concentration in local areas will lead to the formation of the η phase, while excessively high carbon concentration will lead to the formation of free carbon. Due to the order-of-magnitude difference between the particle size of carbon black (20-100nm) and that of ultrafine tungsten powder (<1.0μm), traditional mixing methods struggle to achieve microscopically uniform composite composition, which is the core technical bottleneck leading to the low combined carbon content in ultrafine tungsten carbide. Furthermore, during the mixing process, ultrafine tungsten powder generates heat through friction and releases heat through oxidation. Increased temperature accelerates the oxidation of tungsten powder (generating WO3), further consuming the carbon source and reducing the combined carbon content. Therefore, temperature control during the mixing process is also a crucial factor in ensuring the combined carbon content. Summary of the Invention

[0004] To address the technical problems in the existing ultrafine tungsten carbide mixing process, such as difficulty in breaking up agglomerates, poor mixing uniformity, and oxidation caused by temperature rise, this application proposes a mixing device and method to improve the carbon content of tungsten carbide. Through the synergistic effect of high-frequency shearing by flying knives and low-speed diffusion by spiral ribbon, combined with a segmented cooling mixing process, high uniformity of tungsten powder and carbon black can be achieved.

[0005] To at least partially solve the above problems, the present invention provides a mixing device for improving tungsten carbide-carbon alloys, comprising: a silo structure including a shell and a silo cover connected to each other, forming a sealed mixing chamber between the shell and the silo cover, and the shell having a hollow partition for adjusting the temperature of the sealed mixing chamber; a mixing mechanism including a drive shaft rotatably connected to the silo cover and a screw ribbon mounted on the drive shaft, the screw ribbon being located in the sealed mixing chamber and having triangular cuts at its edges; and a flying knife mechanism located on the material throwing path of the screw ribbon, including a cutter shaft rotatably connected to the side wall of the shell, a cutter hinged to the cutter shaft, and an angle adjustment component for adjusting the tilt angle of the cutter; the angle adjustment component is drive-connected to the cutter to drive the cutter to rotate around its hinge point to a preset angle and lock it. The above solution uses a high-frequency rotating blade of a flying knife mechanism to forcibly shear and scatter agglomerated powder, breaking up soft agglomerates of tungsten powder and carbon black, and working in conjunction with a mixing mechanism to improve the mixing uniformity of tungsten powder and carbon powder; the triangular cuts on the edge of the spiral ribbon can enhance the turbulence effect and promote diffusion mixing at the micro level; the hollow partition enables temperature control during the material mixing process, preventing the ultrafine tungsten powder from oxidizing due to temperature rise, thus effectively solving the problems of low combined carbon and η phase formation caused by uneven mixing in the production of ultrafine tungsten carbide.

[0006] Preferably, the triangular cuts are arranged in multiple rows along the axial direction of the helical ribbon. The ratio of the depth h of each row of triangular cuts to the width W of the helical ribbon is h / W = 0.15-0.25; the ratio of the spacing L between adjacent triangular cuts in the same row to the base length b of the cut is L / b = 2-3; and the size of the triangular cuts on each level of the helical ribbon decreases progressively from top to bottom, that is, the depth h and the base length b of the triangular cuts decrease proportionally as the outer diameter of the helical ribbon decreases. This scheme, through the specific size design of the triangular cuts, can improve the turbulence intensity by 30%-40% while ensuring the structural strength of the helical ribbon. The spacing between adjacent cuts in the same row is 2-3 times the base length of the cut, avoiding mutual cancellation of eddies. The progressively decreasing cut size from top to bottom, combined with the variable diameter design, forms an axial gradient mixing effect.

[0007] Preferably, the spiral ribbon has a variable diameter and variable pitch structure, with its outer diameter divided into three stages from top to bottom: a first-stage outer diameter D1, a second-stage outer diameter D2, and a third-stage outer diameter D3, where D1 > D2 > D3. The transition between adjacent outer diameter stages is connected by a conical surface. The gap between the spiral ribbon portion containing the first-stage outer diameter D1 and the inner wall of the shell is 5 to 8 mm, while the gap between the spiral ribbon portion containing the third-stage outer diameter D3 and the inner wall of the shell is 3 to 5 mm. This design, through its variable diameter configuration, allows for rapid convection circulation of the upper material within a larger space, achieving macroscopically uniform mixing; the lower material experiences stronger shearing action within a smaller gap, promoting microscopic diffusion mixing.

[0008] Preferably, the flying knife mechanism includes: a support base fixedly connected to the side wall of the housing; a motor A mounted on the support base via a motor mount, the motor A having a hollow output shaft with internal threads; a cutter shaft, one end of which is connected to the hollow output shaft, and the other end of which extends into a sealed mixing chamber, and the cutter shaft is rotatably connected to the housing via a bearing A; and multiple cutters arranged along the axial direction of the cutter shaft, each cutter being rotatably connected to the cutter shaft. This preferred embodiment drives the cutter shaft to rotate at high speed via motor A, causing the multiple cutters to perform high-frequency shearing on the material, effectively breaking up agglomerates.

[0009] Preferably, the angle adjustment assembly includes: an adjusting bolt, which is threaded into the interior of the hollow output shaft, and the side of the hollow output shaft has an opening for operating the adjusting bolt; a disc, disposed within the hollow output shaft and connected to the adjusting bolt; a movable rod, coaxially slidingly fitted within the inner cavity of the cutter shaft, and one end of the movable rod is connected to the disc; multiple connecting seats, each rotatably connected to the outer surface of the movable rod via a hinge shaft, and the tube wall of the cutter shaft has elongated holes for each connecting seat to pass through; and multiple connecting rods, one end of each connecting rod hinged to the corresponding connecting seat, and the other end hinged to the middle of the corresponding cutter. The adjusting bolt generates axial displacement by rotation, and drives the movable rod to slide synchronously within the cutter shaft via the disc, thereby driving multiple cutters to rotate synchronously around their corresponding hinge points through each connecting seat and each connecting rod. By rotating the adjusting bolt to drive the movable rod to move axially, the synchronous adjustment of the cutter angle is achieved through the linkage mechanism. The operation is simple, and the shearing intensity can be flexibly adjusted according to the material characteristics.

[0010] Preferably, the flying knife mechanism consists of two sets, symmetrically arranged about the central axis of the housing. Axially, both sets are located within the region of the third-stage outer diameter D3 of the spiral ribbon. Radially, the radial gap between the shearing circumference formed by the rotating blades and the inner edge of the spiral ribbon is 10 to 20 mm, allowing the material thrown by the ribbon to directly enter the shearing path of the blades. This design, with its two symmetrically arranged flying knife mechanisms, enhances the shearing and dispersing effect. The specific positioning ensures that the material immediately enters the flying knife shearing area after being thrown by the ribbon, improving mixing efficiency.

[0011] Preferably, a fixed support mechanism is also included, comprising a support platform and feet screwed to the lower end of the support platform. The upper surface of the support platform is connected to the shell. A flow channel for guiding the flow of cooling medium is provided within the hollow partition. A water inlet is connected to the lower side of the shell, and a water outlet and an air inlet valve are connected to the upper side. Both the water inlet and the water outlet are connected to the flow channel. A feed valve for adding powdered materials and a vent valve for regulating the air pressure inside the chamber are installed on the cover. A discharge valve for discharging the mixture is installed at the bottom of the shell. The above scheme provides rigid support and a stable installation foundation for the entire system through the fixed support mechanism; the cooling medium flow channel, in conjunction with the water inlet and water outlet, achieves efficient temperature control; the feed valve, vent valve, and discharge valve ensure the stability of material feeding and discharging and the regulation of air pressure inside the chamber.

[0012] Preferably, the mixing mechanism further includes: a reducer, the lower end of which is fixedly mounted on the upper surface of the silo cover; a motor B, connected to the upper end of the reducer; and a drive shaft rotatably connected to the center of the silo cover via a sealed bearing seat. One end of the drive shaft is connected to the output end of the reducer, and the other end is connected to a screw belt, so that the screw belt is driven to rotate within the sealed mixing chamber through the cooperation of the motor B and the reducer. The stable low-speed rotation of the screw belt, achieved through the cooperation of the motor B and the reducer, drives the material to undergo axial circulation and radial shearing.

[0013] Furthermore, the present invention also provides a method for achieving uniform mixing according to any one of the above-described mixing apparatuses, the method comprising the following steps: S1. Tungsten Powder Premixing and Loosening: Start the cooling medium circulation and introduce inert gas through the vent valve and intake valve to replace the air in the sealed mixing chamber; put the re-weighed tungsten powder into the shell and start motors B and A; set the screw speed to 28-30 r / min, adjust the angle between the cutter and the cutter shaft to 70°-90° by adjusting the bolt to drive the angle adjustment component, set the speed of the flying knife mechanism to 1200-1500 r / min, and run for 30-60 minutes to remove tungsten powder agglomeration and activate the particle surface; S2, Intermediate Cooling: Open the discharge valve to unload the premixed tungsten powder and transfer it to a cold storage environment for cooling, so that the temperature of the tungsten powder drops to 30-45°C, in order to inhibit the oxidation reaction in the subsequent mixing process; S3. Carbon Mixing: The cooled tungsten powder is reintroduced into the shell and an inert atmosphere is maintained; the re-weighed carbon black is added in proportion, and motors B and A are started; the screw conveyor speed is set to 28-30 r / min, and the angle between the cutter and the cutter shaft is adjusted to 45°-65° by adjusting the bolt to increase the radial shearing force. The speed of the flying knife mechanism is increased to 3300-3500 r / min and run for 120-200 minutes. The high-speed flying knife is used to shear and disperse the carbon black agglomerates and throw them onto the surface of the tungsten powder particles. Uniform mixing is achieved by the screw conveyor rolling.

[0014] The above method uses a segmented mixing process to first premix the tungsten powder to break up the tungsten powder agglomerates into individual tungsten powder particles, and then add carbon black for main mixing. By controlling the speed of the flying knife mechanism and the speed of the screw, and in conjunction with the jacket cooling system, the oxidation of the ultrafine powder and carbon volatilization are effectively suppressed, and a high degree of uniformity in the mixing of tungsten powder and carbon black is achieved.

[0015] Preferably, in step S3, the amount of carbon black fed is dynamically adjusted based on the oxygen content monitoring value in the tungsten powder after the end of stage S1. The molar ratio of tungsten to carbon is set in the range of 1:1.01-1.02, and for every 0.1% increase in oxygen content, the molar ratio of carbon fed is increased by 0.005-0.008. At the same time, the radial shear force generated by the flying knife mechanism and the axial cyclic thrust generated by the screw ribbon form a combined force in the third-stage outer diameter D3 region, so that the carbon black particles are distributed in an interlocking state on the surface of the tungsten powder particles, achieving molecular-level uniform mixing.

[0016] The above scheme compensates for carbon volatilization during the carbonization process by dynamically adjusting the carbon content, ensuring the stability of the combined carbon content of the final product; the synergistic effect of the flying knife and the spiral ribbon in a specific area achieves uniform coating of carbon black on the surface of tungsten powder.

[0017] In step S2, after the premixed tungsten powder is transferred to the cold storage, it needs to be placed in a sealed container and filled with high-purity nitrogen or argon gas at a pressure of 0.02-0.05MPa for positive pressure protection. During the cooling process, the material is turned over every 20-30 minutes to ensure that the temperature of each part of the material drops uniformly to 30-45℃, so as to provide a stable cold source support for the subsequent carbon blending process.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: 1. Significantly increased and highly stable combined carbon content: Through the synergistic effect of high-frequency shearing (3300-3500 r / min) with a flying knife and low-speed diffusion (28-30 r / min) with a spiral ribbon, the soft agglomeration of ultrafine tungsten powder and nano-carbon black is effectively broken, allowing carbon black to uniformly coat the surface of the tungsten powder, ensuring complete carbonization. Using the mixing device and method of this invention, the combined carbon content of tungsten carbide products can stably reach 6.10%-6.13%, with batch-to-batch fluctuations ≤ ±0.02%, and the free carbon content ≤ 0.05%, avoiding the formation of the η phase (W2C) and free carbon segregation.

[0019] 2. Suppress oxidation and reduce carbon loss: The segmented cooling process (cooling after premixing and cooling after main mixing), combined with the jacket cooling system, effectively controls the temperature rise of the mixture to <100°C, suppresses the oxidation reaction of tungsten powder (2W+3O2→2WO3), reduces the unnecessary consumption of carbon source due to the reduction of tungsten oxide (WO3+3C→W+3CO), and improves carbon utilization.

[0020] 3. Suitable for ultrafine / nanoscale powders: The angle of the flying knife mechanism is adjustable (45°-90°), allowing for adjustment of shear intensity according to the tungsten powder particle size (ultrafine <0.5μm or nanoscale <0.1μm). This effectively breaks up agglomerates while avoiding excessive crushing that could lead to powder particle size degradation. The triangular cut at the edge of the spiral ribbon generates additional turbulence, enhancing the microscopic mixing uniformity of ultrafine powders.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the overall structure of the mixing device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the ribbon structure according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the flying knife mechanism structure according to an embodiment of the present invention; Figure 4 This is a cross-sectional schematic diagram of the flying knife mechanism according to an embodiment of the present invention; Figure 5 These are scanning electron microscope images of tungsten carbide powder obtained in the embodiments of the present invention.

[0023] Icons: 101, Foot; 102, Support Platform; 201, Motor A; 202, Support Base; 203, Motor Base; 204, Cutter Shaft; 205, Bearing A; 206, Movable Rod; 207, Connecting Seat; 208, Connecting Rod; 209, Cutting Tool; 210, Hinge Shaft; 211, Circular Plate; 212, Adjusting Bolt; 301, Housing; 302, Water Inlet; 303, Water Outlet; 304, Feed Valve; 305, Discharge Valve; 306, Air Inlet Valve; 307, Bin Cover; 308, Exhaust Valve; 401, Ribbon; 402, Reducer; 403, Motor B. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0025] The following is in conjunction with the appendix Figures 1-5 The embodiments further illustrate the present invention in detail, so that those skilled in the art can implement it based on the description.

[0026] Example 1:

[0027] like Figures 1-5 As shown in the figure, this embodiment provides a mixing device for improving the mixing of tungsten carbide and carbon. The device mainly includes three core components: a silo structure, a mixing mechanism, and a flying knife mechanism. The three components work together to achieve highly uniform mixing of ultrafine tungsten powder and carbon black.

[0028] The silo structure includes an interconnected shell 301 and a silo cover 307, forming a sealed mixing chamber. The shell 301 has a hollow partition for regulating the temperature of the sealed mixing chamber. Specifically, the shell 301 serves as the main support of the entire mixing device, and its top is fastened to the silo cover 307 via bolt assemblies, thereby enclosing the aforementioned sealed mixing chamber. This sealed environment effectively isolates external air, providing the necessary conditions for subsequent mixing operations under an inert atmosphere and preventing oxidation of the ultrafine tungsten powder during mixing. Furthermore, the shell 301 has a hollow partition inside its wall. This hollow partition is not a simple sandwich structure but serves as a flow channel for the heat exchange medium. In practical applications, by introducing cooling water or heat transfer oil into the hollow partition, the heat generated by friction and shear during mixing can be promptly removed, thereby precisely controlling the temperature within the sealed mixing chamber and suppressing powder oxidation reactions caused by temperature rise. This is crucial for ensuring the final carbon content of the tungsten carbide product.

[0029] The mixing mechanism includes a drive shaft rotatably connected to the hopper cover 307 and a spiral ribbon 401 mounted on the drive shaft. The spiral ribbon 401 is located within a sealed mixing chamber and has triangular slits along its edges. Specifically, the drive shaft passes through the center of the hopper cover 307 and extends into the sealed mixing chamber, with its axis coinciding with the central axis of the housing 301. The spiral ribbon 401 is fixedly mounted to the lower end of the drive shaft and rotates at a low speed under the drive of the drive shaft. The spiral ribbon 401 extends in a spiral shape, with its outer edge close to the inner wall of the housing 301. In this invention, the edge of the spiral ribbon 401 is not a traditional smooth structure, but rather has several triangular slits. The triangular slits are preferably isosceles triangles, with their apex pointing towards the rotation direction of the spiral ribbon 401. When the spiral ribbon 401 rotates and causes the material to tumble upwards, the material flowing through these triangular slits will generate local turbulence and vortices. This turbulence effect can break the laminar flow state, promote the diffusion and mixing of the material at the microscopic level, and thus improve the mixing uniformity. It should be understood that although a triangular cut is described in this embodiment, in other embodiments, the shape of the cut may be semi-circular, trapezoidal, or other geometric shapes that can generate turbulence, as long as they can disrupt laminar flow and enhance diffusion.

[0030] The flying knife mechanism is located on the material throwing path of the screw ribbon 401, and includes a cutter shaft 204 rotatably connected to the side wall of the housing 301, a cutter 209 hinged to the cutter shaft 204, and an angle adjustment component for adjusting the tilt angle of the cutter 209; the angle adjustment component is connected to the cutter 209 in a transmission connection to drive the cutter 209 to rotate around its hinge point to a preset angle and lock it. In this invention, the flying knife mechanism is mounted on the side wall of the housing 301, with its cutter shaft 204 extending horizontally into the sealed mixing chamber. Multiple cutters 209 are hinged to the cutter shaft 204. These cutters 209 generate strong centrifugal and shearing forces under the high-speed rotation of the cutter shaft 204. The angle adjustment component is a key part of the flying knife mechanism, internally connected to the cutters 209 via mechanical transmission. The operator can adjust the angle adjustment component to change the tilt angle of the cutters 209 relative to the axis of the cutter shaft 204 and lock it at a preset angle. This angle adjustment function allows the flying knife mechanism to flexibly adjust the shearing intensity and throwing direction according to the characteristics of the material (such as particle size, hardness, and degree of agglomeration). For example, when processing easily agglomerated ultrafine powders, the cutter angle can be adjusted to obtain the best dispersing effect.

[0031] In this embodiment, the flying knife mechanism is located on the material throwing path of the screw ribbon 401, which is a key layout for achieving efficient mixing. The material throwing path refers to the trajectory area where the material is thrown and scattered under gravity after the screw ribbon 401 lifts the material from the bottom to the top during rotation. The blades 209 of the flying knife mechanism extend into this area, and when the material is thrown down by the screw ribbon 401, it immediately enters the high-speed shearing area of ​​the flying knife mechanism. At this time, the flying knife mechanism forcibly shears and disperses the material in the throwing state, breaking up the soft agglomerates of tungsten powder and carbon black. The synergistic operation mode of screw ribbon throwing and flying knife shearing in this invention allows the material to be forcibly dispersed when it is in a loose and suspended state, avoiding the problem of material accumulation and difficulty in dispersing in traditional mixing, thereby significantly improving mixing efficiency. Through the cooperation of the above-mentioned silo structure, mixing mechanism and flying knife mechanism, the device of this embodiment can achieve efficient and uniform mixing of ultrafine tungsten carbide powder in a closed and low-temperature environment, effectively solving the problems of low combined carbon and η phase formation caused by uneven mixing.

[0032] Example 2:

[0033] like Figures 1-5 As shown, this embodiment, based on Embodiment 1, provides a detailed description of the specific structural parameters of the screw ribbon 401. For example... Figure 2 As shown, the triangular cuts are arranged in multiple rows along the axial direction of the threaded ribbon 401. The ratio of the depth h of each row of triangular cuts to the width W of the threaded ribbon 401, h / W, is in the range of 0.15-0.25. The ratio of the spacing L between adjacent triangular cuts in the same row to the length b of the cut base, L / b, is in the range of 2-3. Furthermore, from top to bottom, the size of the triangular cuts on each level of the threaded ribbon 401 gradually decreases.

[0034] The triangular cuts in this invention are preferably isosceles triangles, with their apex pointing towards the rotation direction of the helical ribbon 401. When the helical ribbon 401 rotates and causes the material to tumble upwards, the material flowing through these triangular cuts will generate local turbulence and vortices. This turbulence effect can break the laminar flow state and promote the diffusion and mixing of the material at the microscopic level. Extensive CFD simulations and experiments have shown that when the h / W ratio is controlled within the range of 0.15-0.25, for example, h / W=0.2, the turbulence intensity can be increased by 30%-40% while ensuring the structural strength of the helical ribbon 401. If the h / W ratio is too small (e.g., less than 0.15), the resulting turbulence effect is weak, and its promoting effect on micro-mixing is not significant; if the h / W ratio is too large (e.g., greater than 0.25), it will excessively weaken the blade strength of the helical ribbon 401, making it prone to deformation or breakage when processing high-density tungsten powder. The ratio L / b of the spacing L between adjacent triangular cuts in the same row to the length b of the cut base is controlled within the range of 2-3. This aims to prevent the vortices generated by adjacent cuts from canceling each other out and to ensure the effective superposition of turbulence effects. The size of the triangular cuts decreases gradually from top to bottom. Combined with the variable diameter structure described below, this forms an axial gradient mixing effect, that is, the upper region is dominated by macroscopic convection, while the lower region is dominated by microscopic shear diffusion.

[0035] Furthermore, the screw ribbon 401 has a variable diameter and variable pitch structure, with its outer diameter divided into a first-stage outer diameter D1, a second-stage outer diameter D2, and a third-stage outer diameter D3 from top to bottom, where D1>D2>D3; the transition between adjacent outer diameter stages is connected by a conical surface; wherein, the gap between the screw ribbon portion containing the first-stage outer diameter D1 and the inner wall of the housing 301 is 5 to 8 mm, and the gap between the screw ribbon portion containing the third-stage outer diameter D3 and the inner wall of the housing 301 is 3 to 5 mm. The variable diameter and variable pitch design of this invention allows the upper region of the screw ribbon 401 to have a larger outer diameter D1, forming a larger gap (5-8 mm) with the inner wall of the housing 301. This spacious area allows the material to quickly circulate axially and undergo macroscopic convection under the drive of the screw ribbon 401, achieving preliminary uniform mixing. As the material flows downwards, the outer diameter of the spiral ribbon 401 gradually decreases to D3, and the gap between it and the inner wall of the shell 301 shrinks to 3-5 mm. This narrow gap region exerts a strong shearing and compressive effect on the material, forcing the material particles closer together and promoting diffusion mixing at the microscopic level. Adjacent outer diameters are smoothly transitioned through a conical surface, preventing material stagnation or dead zones in the transition area. This gradient mixing mode of "macroscopic convection in the upper part and microscopic shearing in the lower part," combined with the turbulence effect generated by the triangular cut, can significantly improve the mixing uniformity of tungsten powder and carbon black, especially for ultrafine tungsten powder and nano-carbon black with significant particle size differences, effectively preventing carbon black agglomeration and localized carbon segregation. It should be understood that although this embodiment provides a specific gap value range, in practical applications, the gap can be appropriately adjusted according to the characteristics of the material (such as particle size, density, and flowability), as long as a gradient mixing effect can be achieved.

[0036] Example 3:

[0037] like Figures 1-5 As shown, this embodiment, based on Embodiment 1, provides a detailed explanation of the specific structure of the flying knife mechanism and its angle adjustment principle. For example... Figure 3 and Figure 4 As shown, the flying knife mechanism includes a support base 202, a motor A201, a cutter shaft 204, and multiple cutters 209. The support base 202 is fixedly connected to the side wall of the housing 301, providing cantilever support for the entire flying knife mechanism. The motor A201 is mounted on the support base 202 via a motor mount 203. Its output shaft is designed as a hollow output shaft with internal threads. This hollow design is one of the key structural features of this embodiment. One end of the cutter shaft 204 is connected to the hollow output shaft, and the other end extends into the sealed mixing chamber. The cutter shaft 204 and the housing 301 are rotatably connected via a bearing A205 to ensure stability during high-speed rotation. Multiple cutters 209 are arranged axially along the cutter shaft 204, and each cutter 209 is rotatably connected to the cutter shaft 204. The hinged connection allows the angle of the cutter 209 to be adjustable.

[0038] Furthermore, to achieve precise adjustment and locking of the tool 209 angle, this embodiment employs a unique angle adjustment assembly. This assembly includes an adjusting bolt 212, a disc 211, a movable rod 206, multiple connecting seats 207, and multiple connecting rods 208. The adjusting bolt 212 is threaded into the hollow output shaft of the motor A201, and an opening for operating the adjusting bolt 212 is provided on the side of the hollow output shaft. The operator can use a tool to rotate the adjusting bolt 212 through this opening, and after adjustment, the bolt 212 can be stabilized and prevented from loosening by tightening a nut or by clamping a tightening screw against the side wall of the central control output shaft. The disc 211 is disposed within the hollow output shaft and connected to the adjusting bolt 212. The movable rod 206 is coaxially slidably fitted within the inner cavity of the tool shaft 204, and one end of the movable rod 206 is connected to the disc 211. Multiple connecting seats 207 are rotatably connected to the outer surface of the movable rod 206 via hinge shafts 210, and elongated holes are provided on the tube wall of the cutter shaft 204 for each connecting seat 207 to pass through. One end of each connecting rod 208 is hinged to the corresponding connecting seat 207, and the other end is hinged to the middle of the corresponding cutter 209. The working principle of this angle adjustment assembly is based on the cooperation of screw drive and linkage mechanism. When the operator rotates the adjusting bolt 212, the adjusting bolt 212 generates axial displacement under the action of thread engagement, and drives the movable rod 206 to slide synchronously in the cutter shaft 204 via the disc 211. The axial movement of the movable rod 206 drives the connecting seat 207 to move axially, and then pushes or pulls the cutter 209 to rotate around its hinge point with the cutter shaft 204 through the connecting rod 208, thereby realizing the synchronous adjustment of the angle of multiple cutters 209. The advantage of the nested structure of the hollow output shaft and the movable rod 206 is that it completely integrates the adjustment mechanism, resulting in a compact structure and avoiding interference from external adjustment mechanisms on material flow. It also ensures a tight seal during adjustment, preventing dust from entering the motor. Furthermore, although this embodiment describes manual adjustment via the adjusting bolt 212, in other embodiments, an electric push rod or hydraulic cylinder can be used instead of the adjusting bolt 212 for automated adjustment. Additionally, the angle adjustment range of the cutter 209 is preferably 45 to 90 degrees to adapt to the shearing requirements of different materials. For example, when processing easily agglomerated ultrafine powders, the angle of the cutter 209 can be adjusted to a smaller range of 45 to 65 degrees to obtain a larger radial shearing force; while when processing powders with good flowability, the angle can be adjusted to a larger range of 70 to 90 degrees to reduce shearing intensity and avoid excessive crushing. This invention, through its flexible angle adjustment function, enables the mixing device to adapt to the mixing process requirements of various materials, significantly improving the versatility and process adaptability of the equipment.

[0039] Example 4:

[0040] like Figures 1-5As shown, this embodiment, based on embodiment 3, provides a detailed description of the spatial layout of the flying knife mechanism and the screw ribbon 401. Two sets of flying knife mechanisms are provided, symmetrically arranged about the central axis of the housing 301. In terms of axial height, both sets of flying knife mechanisms are located in the region where the third-stage outer diameter D3 of the screw ribbon 401 is located. In terms of radial position, the radial gap between the shearing circumference edge formed by the rotation of the cutter 209 and the inner edge of the screw ribbon 401 is 10 to 20 mm, so that the material thrown by the screw ribbon 401 can directly enter the shearing path of the cutter 209. Specifically, the symmetrical arrangement of the two sets of flying knife mechanisms means that the axes of the cutter shafts 204 of the two flying knife mechanisms intersect at the central axis of the housing 301, and the projections of the two on the horizontal plane form a 180-degree angle. The symmetrical layout can simultaneously shear and break up the material from two opposite directions, which not only balances the radial impact force on the housing 301 and reduces equipment vibration, but more importantly, it forms a cross shearing field. The material is repeatedly cut by the high-speed cutters 209 in two directions, which greatly improves the crushing efficiency of agglomerates.

[0041] Regarding the axial height positioning, the flying knife mechanism is located in the region of the third-stage outer diameter D3 of the screw ribbon 401. According to the description in Embodiment 2, region D3 is the region with the smallest outer diameter of the screw ribbon 401 and the smallest gap with the inner wall of the housing 301. In this region, the material experiences the greatest compressive force, has the highest material density, and the largest initial velocity when thrown upwards by the screw ribbon 401. Therefore, after being thrown out in region D3, the material's trajectory is most concentrated and possesses greater kinetic energy. Setting the flying knife mechanism at this height ensures that the cutter 209 captures the material flow with the highest density and greatest kinetic energy, thereby maximizing shearing efficiency. If the flying knife mechanism were located in region D1 or D2, the material in these areas would be relatively loose, resulting in a dispersed throwing trajectory, which would cause some material to fail to enter the effective shearing range of the cutter 209, leading to ineffective cycles.

[0042] Regarding the setting of the radial clearance, the radial clearance between the shearing circumference edge formed by the rotation of the cutter 209 and the inner edge of the ribbon 401 is controlled between 10 and 20 mm. This clearance range is the optimal range verified by a large number of experiments. If the clearance is less than 10 mm, the airflow field generated by the high-speed rotation of the cutter 209 will interfere with the ribbon 401, causing material accumulation on the surface of the ribbon 401, and even posing a risk of collision between the cutter 209 and the ribbon 401; if the clearance is greater than 20 mm, the material flow thrown out by the ribbon 401 will diffuse and decelerate before reaching the cutter 209, and some material will escape from the edge of the cutter 209 and cannot be effectively sheared. The clearance of 10 to 20 mm ensures a safe distance between the cutter 209 and the ribbon 401, and also ensures that the material can immediately enter the high-speed shearing zone of the cutter 209 after being thrown out, achieving a seamless connection between throwing and shearing. This layout design allows the material to be forcibly dispersed in each cycle, avoiding the drawback of repeated material circulation but difficulty in dispersion in traditional mixers, and significantly shortening the time required to achieve uniform mixing.

[0043] Example 5:

[0044] like Figures 1-5 As shown, this embodiment, based on the above embodiments, provides a detailed description of the auxiliary support, cooling, feeding / discharging, and drive systems of the mixing device. These peripheral systems provide necessary guarantees for the stable operation of the mixing device, especially the cooling system, which plays a crucial role in suppressing the oxidation of ultrafine powder. The mixing device in this embodiment also includes a fixed support mechanism, which comprises a support platform 102 and feet 101 screwed to the lower end of the support platform 102. The upper surface of the support platform 102 is connected to the housing 301. Specifically, the support platform 102, as the load-bearing foundation of the entire mixing device, is typically welded from structural steel and possesses sufficient rigidity and strength to support the weight of the housing 301 and its internal materials. The feet 101 are installed at the four corners or perimeter of the support platform 102 via threaded connections. The operator can adjust the height by rotating the feet 101, thereby leveling the support platform 102 on uneven ground and ensuring the stability of the mixing device during operation. It should be understood that although this embodiment describes a screw connection, in other embodiments, the foot 101 can also be fixed by welding or snap-fit ​​connection, as long as it can achieve the function of support and leveling.

[0045] The hollow partition of the shell 301 contains a flow channel for guiding the flow of cooling medium. A water inlet 302 is connected to the lower side of the shell 301, and a water outlet 303 and an air inlet valve 306 are connected to the upper side. Both the water inlet 302 and the water outlet 303 are connected to the flow channel. Specifically, the interior wall of the shell 301 is designed with a spiral or annular flow channel. Cooling water is pumped in from the water inlet 302 on the lower side, flows upwards along the flow channel, absorbs the heat generated during the mixing process, and then flows out from the water outlet 303 on the upper side. This bottom-in, top-out design conforms to thermodynamic principles, facilitates the filling of the entire flow channel with cooling medium, avoids air resistance, and thus improves heat exchange efficiency. The air inlet valve 306 is used to introduce inert gases such as nitrogen or argon into the sealed mixing chamber to replace the air and create an oxygen-free environment. The mechanism by which the cooling channel suppresses temperature rise oxidation is as follows: During the high-speed shear mixing process of ultrafine tungsten powder, the friction between particles is intense, easily generating local high temperatures. If heat is not dissipated in time, the surface of the tungsten powder will rapidly oxidize to form WO3. WO3 will consume the carbon source during the subsequent carbonization process, leading to a decrease in the combined carbon content of the final product. In this embodiment, the circulating cooling water in the hollow partition controls the temperature of the inner wall of the shell 301 at a low level (e.g., ≤30℃), thereby effectively suppressing the oxidation reaction of the tungsten powder and ensuring the stability of the combined carbon content of the tungsten carbide product. The hopper cover 307 is equipped with a feed valve 304 for adding powdered materials and a vent valve 308 for regulating the air pressure inside the cavity. The bottom of the shell 301 is equipped with a discharge valve 305 for discharging the mixture. Specifically, the feed valve 304 is usually a pneumatic or electric butterfly valve, which has good sealing performance and can prevent dust leakage. The vent valve 308 works in conjunction with the inlet valve 306. During air replacement, the inlet valve 306 introduces inert gas, while the vent valve 308 opens to release the air, forming a gas replacement circuit. During the mixing process, the vent valve 308 automatically opens or closes according to the internal pressure, maintaining a slightly positive pressure state to prevent external air from seeping in. The discharge valve 305 is located at the tapered end of the housing 301, facilitating the smooth discharge of the mixed material under gravity. The coordinated control of the inlet valve 304, vent valve 308, discharge valve 305, and inlet valve 306 achieves a closed-loop operation of the mixing process, avoiding material contamination and the risk of dust explosion.

[0046] The mixing mechanism also includes a reducer 402 and a motor B403. The lower end of the reducer 402 is fixedly mounted on the upper surface of the hopper cover 307; the motor B403 is connected to the upper end of the reducer 402; the drive shaft is rotatably connected to the center of the hopper cover 307 via a sealed bearing housing. One end of the drive shaft is connected to the output end of the reducer 402, and the other end is connected to the screw belt 401, so that the screw belt 401 is driven to rotate in the sealed mixing chamber through the cooperation of the motor B403 and the reducer 402. Specifically, the motor B403 is usually a variable frequency motor, which can adjust the speed according to process requirements. The reducer 402 reduces the high speed of the motor B403 to the operating speed required by the screw belt 401 (e.g., 28-30 r / min), while increasing the output torque. The drive shaft passes through the center of the hopper cover 307 and is connected to the hopper cover 307 via a sealed bearing housing. This sealed bearing housing not only supports the rotation of the drive shaft, but also prevents dust leakage from the chamber through a sealing ring or packing. The power from motor B403 is transmitted sequentially to the screw belt 401 via reducer 402 and drive shaft, driving the screw belt 401 to rotate at low speed, thus causing the material to undergo axial circulation and radial shearing. This vertical drive layout has a compact structure, high transmission efficiency, and is easy to maintain.

[0047] Example 6:

[0048] like Figures 1-5 As shown, this embodiment provides a method for achieving uniform mixing using the mixing device described in any of the above embodiments. This method effectively suppresses the oxidation of ultrafine powder and improves the mixing uniformity through segmented process control. The method specifically includes the following steps: Step S1, Tungsten Powder Premixing and Loosening: Start the cooling medium circulation, and introduce inert gas through the vent valve 308 and the inlet valve 306 to replace the air in the sealed mixing chamber; put the re-weighed tungsten powder into the housing 301, and start motors B403 and A201; set the speed of the screw 401 to 28-30 r / min, and adjust the angle between the cutter 209 and the cutter shaft 204 to 70°-90° by adjusting the angle adjustment assembly through the adjusting bolt 212; set the speed of the flying knife mechanism to 1200-1500 r / min, and run for 30-60 minutes to remove tungsten powder agglomeration and activate the particle surface.

[0049] Specifically, the inert gas is preferably nitrogen or argon, and the replacement process must continue until the oxygen content in the chamber is below a preset threshold (e.g., 0.1%) to prevent the tungsten powder from oxidizing during subsequent stirring. Re-weighing refers to re-weighing the tungsten powder before feeding to eliminate proportioning errors caused by transportation losses. In this step, the screw conveyor 401 rotates at low speed, causing the material to macroscopically tumble, keeping it in a loose state. Crucially, the angle of the cutter 209 is adjusted to a relatively large 70°-90° (e.g., 80°), which results in a larger windward surface for the cutter 209, providing a stronger pushing force but weaker shearing force on the material. Combined with a relatively low rotation speed (1200-1500 r / min), this effectively breaks up the pseudo-particle agglomerates formed during tungsten powder transportation, while avoiding the breakage or particle size degradation of the tungsten powder particles due to excessive shearing. Furthermore, this process also activates the surface of the tungsten powder particles, removing trace amounts of adsorbed gases and providing a clean surface for subsequent carbon black adhesion.

[0050] Step S2, Intermediate Cooling: Open the discharge valve 305 to unload the premixed tungsten powder and transfer it to a cold storage environment for cooling, so that the temperature of the tungsten powder drops to 30-45°C, in order to inhibit the oxidation reaction in the subsequent mixing process.

[0051] Specifically, although cooling measures were taken during the premixing process, the large specific surface area of ​​ultrafine tungsten powder meant that frictional heat generation still caused the powder temperature to rise. If carbon was directly added during the main mixing process, the high temperature would significantly accelerate the oxidation reaction of the tungsten powder (2W + 3O2 → 2WO3). The generated WO3 would consume the carbon source during the subsequent carbonization process (WO3 + 3C → W + 3CO), resulting in a decrease in the carbon content of the final product. Therefore, this embodiment innovatively introduces an intermediate cooling step, unloading the premixed tungsten powder and transferring it to a low-temperature environment (such as a cold storage at 0-5°C) for forced cooling, reducing the overall powder temperature to a safe range of 30-45°C. This step breaks the heat accumulation chain, suppressing the kinetics of the oxidation reaction at its source and ensuring carbon retention during the subsequent main mixing process. It should be understood that the cooling method is not limited to a cold storage; an intermediate silo with a cooling jacket can also be used for online cooling.

[0052] Step S3, Carbon Mixing: The cooled tungsten powder is put back into the shell 301 and an inert atmosphere is maintained; the re-weighed carbon black is added in proportion, and motors B403 and A201 are started; the speed of the screw ribbon 401 is set to 28-30 r / min, and the angle between the cutter 209 and the cutter shaft 204 is adjusted to 45°-65° by adjusting bolt 212 to increase the radial shearing force, and the speed of the flying knife mechanism is increased to 3300-3500 r / min. After running for 120-200 min, the high-speed flying knife is used to shear and disperse the carbon black agglomerates and sprinkle them onto the surface of the tungsten powder particles. Uniform mixing is achieved by the tumbling of the screw ribbon 401.

[0053] Specifically, this stage is crucial in determining the uniformity of mixing. Carbon black particles are typically nanometer-sized (e.g., 30-50 nm), making them highly prone to agglomeration. Furthermore, they exhibit a significant size difference compared to micron-sized tungsten powder, making uniform coating difficult to achieve with conventional mixing methods. In this step, the angle of the cutter 209 is adjusted to 45°-65° (e.g., 55°) by adjusting bolt 212. At this angle, the radial shear component of the cutter 209 increases significantly, and combined with a rotation speed of 3300-3500 r / min, an extremely strong shear force field is generated. This high-speed shear force field instantly breaks up carbon black agglomerates into nanometer-sized monomers, and the centrifugal force generated by the cutter's rotation propels them at high speed onto the surface of the tungsten powder particles. Simultaneously, the ribbon 401 continuously tumbles at low speed, causing the tungsten powder particles to constantly reposition themselves, exposing fresh surfaces to accommodate the carbon black particles. This invention utilizes the synergistic action of high-speed shearing and spraying combined with low-speed tumbling and coating to ensure that carbon black is uniformly embedded on the surface of tungsten powder particles, avoiding local carbon segregation, thereby ensuring the completeness of subsequent carbonization reactions and improving the stability of the combined carbon content.

[0054] Example 7:

[0055] like Figures 1-5As shown, this embodiment, based on Embodiment 6, provides a detailed explanation of the dynamic fine-tuning algorithm for the carbon black feed amount in the carbon mixing step S3. In step S3, the carbon black feed amount is dynamically fine-tuned based on the oxygen content monitoring value in the tungsten powder after stage S1. The molar ratio of tungsten to carbon is set within the range of 1:1.01-1.02, and for every 0.1% increase in oxygen content, the molar ratio of carbon feed increases by 0.005-0.008 accordingly. Simultaneously, the radial shear force generated by the flying knife mechanism and the axial cyclic thrust generated by the screw ribbon 401 form a combined force in the third-stage outer diameter D3 region, causing the carbon black particles to be distributed in an interlocking state on the surface of the tungsten powder particles, achieving molecular-level uniform mixing. During the premixing and loosening process of ultrafine tungsten powder, although inert gas protection and cooling measures are adopted, due to the large specific surface area and high activity of ultrafine powder, a trace amount of oxidation reaction will inevitably occur, generating WO3. If the WO3 is fed according to the theoretical stoichiometric ratio (W:C=1:1) during the carbon mixing stage, the carbon source will be consumed during the subsequent high-temperature carbonization process (reaction formula: WO3+3C→W+3CO), resulting in a lower carbon content in the final product. Therefore, this embodiment introduces a dynamic compensation mechanism based on oxygen content monitoring. The specific logic of this dynamic fine-tuning algorithm is as follows: First, after the S1 stage, the oxygen content in the tungsten powder is sampled and detected. Assume that the initial molar ratio of tungsten to carbon is set to 1:1.01 (i.e., the basic compensation amount is 0.01, used to compensate for carbon volatilization during the carbonization process). If the oxygen content is found to be 0.1% higher than when the raw materials entered the warehouse, it means that a corresponding amount of WO3 has been generated. According to the stoichiometric relationship, reducing 1 mole of WO3 requires the consumption of 3 moles of carbon. Therefore, in order to offset this additional carbon loss, the system automatically increases the molar ratio of carbon feed by 0.005-0.008. For example, if the basic molar ratio is 1:1.01, and the oxygen content increases by 0.1%, the adjusted feed molar ratio becomes 1:1.015 to 1:1.018. This dynamic compensation mechanism can precisely match the carbon source consumption, ensuring that the combined carbon content in the final tungsten carbide product remains stable within the ideal range of 6.10%-6.13%, avoiding batch-to-batch quality differences caused by oxidation fluctuations. Furthermore, this embodiment specifically defines the synergistic effect area between the flying knife mechanism and the screw ribbon 401. The radial shear force generated by the flying knife mechanism and the axial cyclic thrust generated by the screw ribbon 401 combine in the third-stage outer diameter region D3. According to the description in Embodiment 2, the D3 region is where the outer diameter of the screw ribbon 401 is smallest and the gap between it and the inner wall of the shell 301 is smallest; the material experiences the greatest extrusion pressure and has the highest density at this region. When the flying knife mechanism generates radial shear force by rotating at a high speed of 3300-3500 r / min in this area, it works in conjunction with the low-speed axial thrust of the screw ribbon 401 to form a composite force field of shearing, compression, and overturning in space.Under this force field, the carbon black particles, sheared at high speed into nanoscale, are no longer simply attached to the surface of tungsten powder. Instead, they are distributed in an intercalated state in the microscopic pits or grain boundaries on the surface of the tungsten powder particles. This intercalated distribution greatly enhances the bonding force between the carbon black and the tungsten powder, preventing carbon black from falling off or segregating due to vibration during subsequent transport, thus achieving uniform mixing at the molecular level. It should be understood that the above-mentioned molar ratio adjustment range and oxygen content compensation coefficient are optimal ranges obtained by fitting a large amount of experimental data. In practical applications, they can be fine-tuned according to the specific tungsten powder particle size and carbon black purity.

[0056] Example 8:

[0057] like Figures 1-5 As shown, to verify the practical application effect of the device and method of the present invention, this embodiment uses the preparation of ultrafine tungsten carbide powder as an example for detailed explanation. It should be understood that this embodiment is only used to explain the present invention and is not intended to limit the scope of the present invention.

[0058] This embodiment uses the mixing device described in any one of Embodiments 1 to 5. The effective volume of the shell 301 is 1500L, and the jacket cooling area is 2.5m². 2 The specific operation process is as follows: Step S1, Tungsten Powder Premixing and Loosening: Weigh 1000 kg of tungsten powder with a Fisher particle size (Fsss) of 0.6 μm and an initial oxygen content of 0.12%. Feed the tungsten powder into the housing 301 through the feed valve 304. Turn on the cooling water circulation system and introduce nitrogen gas through the vent valve 308 and air inlet valve 306 to replace the air in the sealed mixing chamber until the oxygen content is below 0.1%. Start motors B403 and A201, and set the speed of the screw conveyor 401 to 30 r / min. Adjust the angle adjustment assembly by adjusting bolt 212 to adjust the angle between the cutter 209 and the cutter shaft 204 to 80°, and set the speed of the flying cutter mechanism to 1300 r / min for 45 minutes. During this stage, the large-angle cutter 209, combined with the relatively low speed, mainly loosens the tungsten powder and breaks down false particles, while avoiding excessive crushing of the tungsten powder particles.

[0059] Step S2, Intermediate Cooling: Open the discharge valve 305 to discharge approximately 400 kg of premixed tungsten powder, transfer it to a 5°C cold storage environment for 100 minutes, and measure the powder temperature until it drops to 20°C. This step effectively inhibits the oxidation reaction of tungsten powder during subsequent mixing processes.

[0060] Step S3, Carbon Mixing: The cooled tungsten powder is reintroduced into the shell 301, maintaining an inert atmosphere. 10.8 kg of carbon black with a purity greater than 99.9% and a particle size of 30-50 nm (according to a W:C molar ratio of 1:1.015) is weighed and added into the shell 301. Motors B403 and A201 are started, and the speed of the screw conveyor 401 is set to 30 r / min. The angle between the cutter 209 and the cutter shaft 204 is adjusted to 55° by adjusting bolt 212 to increase the radial shear force, and the speed of the flying knife mechanism is increased to 3400 r / min, running for 180 minutes. During the mixing process, the cooling water flow rate is controlled at 500 L / h, and the water temperature at the outlet of the jacket of shell 301 is controlled below 30°C. In this stage, the high-speed flying knife shears and disperses the carbon black agglomerates and throws them onto the surface of the tungsten powder particles. The low-speed tumbling of the screw conveyor 401 ensures full contact between the two, achieving uniform mixing at the molecular level.

[0061] Step S4, Discharge and Testing: After the main mixing is completed, stop the machine and cool for 450 minutes to allow the material temperature to drop to room temperature. Discharge the material and take samples for testing.

[0062] The test results are as follows: Figure 5 The scanning electron microscope (SEM) images (10,000x magnification) show that the tungsten powder particles are polyhedral with a uniform particle size distribution and an average particle size of approximately 0.6 μm. Carbon black particles (small particles with high brightness) are uniformly adhered to the tungsten powder surface without obvious agglomeration. The composite particles of tungsten powder and carbon black are well dispersed, with no localized carbon segregation or agglomerates observed. This microstructure indicates that the synergistic effect of high-speed shearing by a flying knife (3400 r / min) and low-speed tumbling by a spiral ribbon (30 r / min) effectively achieves uniform coating of nano-carbon black on the surface of ultrafine tungsten powder. After carbonization in a carbonization furnace (1500°C, hydrogen atmosphere), the final tungsten carbide product has a combined carbon content of 6.11%, a free carbon content ≤0.05%, and no η phase (W₂C) was detected. This demonstrates that the present invention effectively solves the problems of low combined carbon and η-phase formation caused by uneven mixing in the production of ultrafine tungsten carbide by the synergistic effect of high-frequency shearing by flying knives and low-speed diffusion by spiral ribbon, combined with a segmented cooling and mixing process.

[0063] Comparative Example 1: A traditional V-type mixer (500L capacity) was used, with 200kg of tungsten powder and 10.8kg of carbon black from the same batch added. The mixing speed was 20r / min, and the mixing time was 12 hours. After carbonization treatment under the same conditions, the discharged material was measured to have a combined carbon content of 6.05% and a free carbon content of 0.08%, with the presence of local η phase. This indicates that the traditional equipment has low mixing efficiency and cannot effectively disperse carbon black agglomerates, resulting in poor mixing uniformity.

[0064] Comparative Example 2: A drum ball mill was used, with 200 kg of tungsten powder, 10.8 kg of carbon black, and 300 kg of cemented carbide balls added at a ball-to-powder ratio of 1.5:1. The mill speed was 30 r / min, and the mixing time was 8 hours. Although the combined carbon content reached 6.10%, the Fe content was detected in the product at 0.08% (from the wear of the grinding balls), and the powder particle size distribution became wider (Fsss decreased from 0.6 μm to 0.4 μm), which is not conducive to the control of subsequent carbonization processes.

[0065] As can be seen from the comparison between the above embodiments and comparative examples, the mixing device and method of the present invention have significant advantages in increasing the content of combined carbon, inhibiting oxidation, avoiding the introduction of impurities, and maintaining the particle size distribution of powder.

[0066] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0067] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. Other modifications can be easily made by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A mixing device for improving the yield of tungsten carbide-carbon compounds, characterized in that, include: The hopper structure includes a shell (301) and a hopper cover (307) connected to each other, forming a sealed mixing chamber between the shell (301) and the hopper cover (307), and the shell (301) has a hollow partition for regulating the temperature of the sealed mixing chamber; The mixing mechanism includes a drive shaft rotatably connected to the bin cover (307) and a screw ribbon (401) mounted on the drive shaft. The screw ribbon (401) is a variable diameter and variable pitch structure, and its outer diameter is divided into a first-stage outer diameter D1, a second-stage outer diameter D2 and a third-stage outer diameter D3 from top to bottom, with D1>D2>D3. The screw ribbon (401) is located in a closed mixing chamber and has triangular cuts on its edge. The gap between the first-stage outer diameter D1 and the inner wall of the shell (301) is greater than the gap between the third-stage outer diameter D3 and the inner wall of the shell (301). The flying knife mechanism consists of two sets. In terms of axial height, both sets of flying knife mechanisms are located in the area where the third outer diameter D3 of the screw ribbon (401) is located and on the material throwing path of the screw ribbon (401). The flying knife mechanism includes a cutter shaft (204) rotatably connected to the side wall of the housing (301), a cutter (209) hinged to the cutter shaft (204), and an angle adjustment component for adjusting the tilt angle of the cutter (209). The angle adjustment component is connected to the cutter (209) in a transmission to drive the cutter (209) to rotate around its hinge point to a preset angle and lock it.

2. The mixing device for improving tungsten carbide-carbon alloying according to claim 1, characterized in that, The triangular cuts are arranged in multiple rows along the axial direction of the threaded ribbon (401). The ratio of the depth h of each row of triangular cuts to the width W of the threaded ribbon (401) is h / W = 0.15-0.

25. The ratio of the distance L between adjacent triangular cuts in the same row to the length b of the bottom edge of the cut is L / b = 2-3. Furthermore, from top to bottom, the size of the triangular cuts on each level of the threaded ribbon (401) gradually decreases.

3. The mixing device for improving tungsten carbide-carbon alloying according to claim 1, characterized in that, The throwing knife mechanism includes: The support base (202) is fixedly connected to the side wall of the housing (301); Motor A (201) is mounted on support base (202) via motor mount (203), and motor A (201) has a hollow output shaft with internal thread; The cutter shaft (204) has one end connected to the hollow output shaft and the other end extended into the sealed mixing chamber. The cutter shaft (204) and the housing (301) are rotatably connected by bearing A (205). And multiple cutting tools (209), the multiple cutting tools (209) are arranged axially along the cutting shaft (204), and each cutting tool (209) is rotatably connected to the cutting shaft (204).

4. The mixing device for improving tungsten carbide-carbon alloying according to claim 3, characterized in that, The angle adjustment components include: An adjusting bolt (212) is screwed into the interior of the hollow output shaft by an external thread, and an opening for operating the adjusting bolt (212) is provided on the side of the hollow output shaft; A circular piece (211) is disposed inside the hollow output shaft and connected to the adjusting bolt (212); The movable rod (206) is coaxially and slidably fitted in the inner cavity of the cutter shaft (204), and one end of the movable rod (206) is connected to the disc (211); Multiple connecting seats (207) are rotatably connected to the outer surface of the movable rod (206) via hinge shafts (210), and the tube wall of the cutter shaft (204) is provided with elongated holes for each connecting seat (207) to pass through; And multiple connecting rods (208), one end of each connecting rod (208) is hinged to the corresponding connecting seat (207), and the other end is hinged to the middle of the corresponding cutting tool (209); The adjusting bolt (212) generates axial displacement by rotation and drives the movable rod (206) to slide synchronously in the cutter shaft (204) via the disc (211), so as to drive multiple cutters (209) to rotate synchronously around their corresponding hinge points through each connecting seat (207) and each connecting rod (208).

5. The mixing device for improving tungsten carbide-carbon alloying according to claim 4, characterized in that, The two sets of flying knife mechanisms are symmetrically arranged about the central axis of the housing (301); in the radial position, the radial gap between the shearing circumference edge formed by the rotation of the cutter (209) and the inner edge of the ribbon (401) is 10 to 20 mm, so that the material thrown by the ribbon (401) can directly enter the shearing path of the cutter (209).

6. The mixing device for improving tungsten carbide-carbon alloying according to claim 5, characterized in that, It also includes a fixed support mechanism, which includes a support platform (102) and a foot (101) screwed to the lower end of the support platform (102). The upper surface of the support platform (102) is connected to the housing (301). The hollow partition is provided with a flow channel for guiding the flow of cooling medium. The lower side of the shell (301) is connected to a water inlet (302), and the upper side is connected to a water outlet (303) and an air inlet valve (306). Both the water inlet (302) and the water outlet (303) are connected to the flow channel. The hopper cover (307) is equipped with a feed valve (304) for adding powdered materials and a vent valve (308) for regulating the air pressure inside the chamber. The bottom of the housing (301) is equipped with a discharge valve (305) for discharging the mixture.

7. The mixing device for improving tungsten carbide-carbon alloying according to claim 6, characterized in that, The mixing mechanism also includes: The reducer (402) is fixedly installed at its lower end on the upper surface of the cover (307); Motor B (403) is connected to the upper end of reducer (402); The drive shaft is rotatably connected to the center of the bin cover (307) through a sealed bearing housing. One end of the drive shaft is connected to the output end of the reducer (402), and the other end of the drive shaft is connected to the screw belt (401) so that the screw belt (401) can be driven to rotate in the sealed mixing chamber through the cooperation of the motor B (403) and the reducer (402).

8. A method for achieving uniform mixing using the mixing device according to claim 7, characterized in that, The method includes the following steps: S1. Tungsten powder premixing and loosening: Start the cooling medium circulation, and introduce inert gas through the vent valve (308) and the inlet valve (306) to replace the air in the sealed mixing chamber; put the weighed tungsten powder into the shell (301), and start motor B (403) and motor A (201); set the speed of the screw (401) to 28-30 r / min, and drive the angle adjustment assembly through the adjusting bolt (212) to adjust the angle between the cutter (209) and the cutter shaft (204) to 70°-90°; set the speed of the flying knife mechanism to 1200-1500 r / min, and run for 30-60 minutes to remove the tungsten powder agglomeration and activate the particle surface; S2, Intermediate Cooling: Open the discharge valve (305) to unload the premixed tungsten powder and transfer it to a cold storage environment for cooling, so that the temperature of the tungsten powder drops to 30-45℃, in order to inhibit the oxidation reaction in the subsequent mixing process; S3, Carbon Mixing: The cooled tungsten powder is put back into the shell (301) and an inert atmosphere is maintained; the re-weighed carbon black is added in proportion, and motors B (403) and A (201) are started; the speed of the screw (401) is set to 28-30 r / min, and the angle between the cutter (209) and the cutter shaft (204) is adjusted to 45°-65° by adjusting the bolt (212) to increase the radial shear force, and the speed of the flying knife mechanism is increased to 3300-3500 r / min. After running for 120-200 min, the high-speed flying knife is used to shear and disperse the carbon black agglomerates and sprinkle them onto the surface of the tungsten powder particles. The screw (401) is used to roll and achieve uniform mixing.

9. The method according to claim 8, characterized in that, In step S3, the amount of carbon black fed is dynamically adjusted based on the oxygen content monitoring value in the tungsten powder after the end of stage S1. The molar ratio of tungsten to carbon is set in the range of 1:1.01-1.02, and the molar ratio of carbon fed increases by 0.005-0.008 for every 0.1% increase in oxygen content. At the same time, the radial shear force generated by the flying knife mechanism and the axial cyclic thrust generated by the screw ribbon (401) form a combined force in the third-stage outer diameter D3 region, so that the carbon black particles are distributed in an interlocking state on the surface of the tungsten powder particles, achieving molecular-level uniform mixing.

Images