Aluminum alloy melt rotary injection purifying device and purifying method

Abstract

The present application belongs to the technical field of non-ferrous metal or alloy melt processing, and particularly relates to an aluminum alloy melt rotary injection purification device and a purification method. The aluminum alloy melt rotary injection purification device comprises a rotor connected with a negative pressure auxiliary discharging device at an upper end, and the negative pressure auxiliary discharging device is connected with a refining agent adding device. The negative pressure auxiliary discharging device comprises a negative pressure generating unit and a flow guide pipe. The negative pressure generating unit is composed of an outer cylinder and an inner cylinder, the upper end of the negative pressure generating unit is connected with the refining agent adding device, an annular cavity is arranged between the inner cylinder and the outer cylinder, an air inlet is arranged on the outer wall surface of the outer cylinder and communicates with the annular cavity, air outlets are uniformly arranged on the inner wall surface of the inner cylinder, and the air outlets communicate with the annular cavity through air outlet channels arranged in the inner cylinder. The refining agent adding device controls the feeding rate of the refining agent by controlling the rotating speed of a feeding gear. The present application reduces secondary hydrogen absorption and oxygen absorption and aluminum alloy melt burning loss in the purification process.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal or alloy melt treatment technology, and particularly relates to the field of aluminum alloy melt purification, specifically to an aluminum alloy melt rotary jet purification device and purification method. Background Technology

[0002] Aluminum alloys possess advantages such as lightweight, high specific strength, good casting and processing properties, and recyclability, making them a high-performance lightweight material widely used in aerospace, automotive, and rail transportation industries. Aluminum alloy melt purification is a key process for obtaining high-quality aluminum alloy castings, and rotary blowing is the main technical means to achieve this purification. Its basic principle relies on the adsorption effect of refining gases (mainly nitrogen or argon) and refining agents (mainly chloride and fluoride salts of alkali metals or alkaline earth metals) to remove hydrogen and alumina inclusions from the aluminum alloy melt.

[0003] In current industrial production, refining gases are typically added to molten aluminum alloy via rotor injection, while the refining agent is drawn in by the vortices formed on the surface of the molten aluminum alloy by the rotor's rotation. While this method of adding the refining agent is simple, it presents two problems: First, it is difficult to add because the refining agent has poor wettability with the molten aluminum alloy, making it difficult for it to fully penetrate the molten aluminum alloy and exert its effect solely through surface vortex entrainment, resulting in low refining agent utilization efficiency. Second, the formation of vortices on the surface of the molten aluminum alloy exacerbates oxidation and hydrogen absorption, leading to secondary contamination of the molten aluminum alloy and increasing the amount of molten aluminum alloy lost during the purification process.

[0004] One technical approach to solving the aforementioned two problems is to inject refining gas and refining agent together into the molten aluminum alloy. This eliminates the need for vortices on the surface of the molten aluminum alloy and ensures that all the refining agent enters the interior of the molten aluminum alloy to perform its purifying effect, thereby significantly reducing aluminum alloy melt loss and improving purification efficiency. However, the current method of injecting refining gas and refining agent together into the molten aluminum alloy mainly relies on the positive pressure provided by high-pressure refining gas to directly blow it from the feeding hopper into the spray channel inside the rotor. This method not only places higher demands on the sealing of the feeding hopper but also easily leads to the accumulation and blockage of refining agent powder at the inlet of the spray channel. Furthermore, due to the physical properties of the refining agent itself, it softens or clumps during the spraying process due to the increase in temperature, causing blockage of the spray channel, thus affecting the continuity of the purification process and increasing the difficulty of rotor cleaning. Existing rotary spraying equipment cannot effectively solve the blockage problem during the refining agent spraying process, which greatly limits the widespread application of this technology.

[0005] In addition, existing technologies also employ a suction fan to create a negative pressure environment for auxiliary feeding. However, this method requires an additional independent fan, increasing equipment complexity, energy consumption, equipment cost, and installation space. Furthermore, the path for generating and transmitting negative pressure is relatively long, leading to leakage and pressure loss issues, resulting in low negative pressure utilization efficiency. Moreover, the generated negative pressure is prone to fluctuations, causing pulsations or even interruptions in the refining agent feeding, affecting the continuity and uniformity of refining agent addition. The magnitude of the negative pressure depends on the fan speed and the sealing condition of the cylinder; however, the relationship between fan speed and negative pressure is non-linear, making it difficult to precisely and sensitively control the refining agent addition rate, resulting in poor adaptability. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a rotary jetting purification device and method for aluminum alloy melt, which features negative pressure-assisted refining agent feeding and rotor cooling and insulation functions, thus solving the problem of refining agent clogging the channel during the jetting process.

[0007] The complete technical solution of this invention is as follows:

[0008] A rotary jet purification device for aluminum alloy melt includes a base; a column capable of horizontal rotation is connected to the base; a crossbeam is connected to the column, one end of the crossbeam is connected to the column, and the other end is connected to a rotor; the crossbeam can move up and down along a track set on the column, and a first motor for driving the rotor to rotate is installed in the middle of the crossbeam.

[0009] The upper end of the rotor is connected to the lower end of the negative pressure auxiliary feeding device, and a cover plate is also installed on the upper end of the rotor; the cover plate has a circular hole in the center for assembly and connection with the rotor, and a baffle is installed below the cover plate; the upper end of the negative pressure auxiliary feeding device is connected to the refining agent addition device.

[0010] The negative pressure assisted feeding device includes an upper negative pressure generating unit and a lower guide pipe. The upper end of the negative pressure generating unit is connected to the refining agent adding device, including an outer cylinder and an inner cylinder. There is an annular cavity between the outer cylinder and the inner cylinder. An air inlet communicating with the annular cavity is provided on the outer wall of the outer cylinder. Air outlets are evenly distributed on the inner wall of the inner cylinder. The air outlets are connected to the annular cavity through an air outlet channel provided in the inner cylinder. The refining gas is blown in through the air inlet and flows through the annular cavity and the air outlet channel in succession. It is blown out from the inner wall of the inner cylinder through the air outlet. The area of ​​the air inlet is larger than the total area of ​​the air outlet. The negative pressure generated by the refining gas flowing out through the air outlet will draw the refining agent falling from the refining agent adding device into the guide pipe and enter the spray channel inside the rotor through the guide pipe.

[0011] The refining agent addition device includes a hopper, a feeding gear located at the outlet of the hopper, and a second motor for driving the feeding gear to rotate. The feeding rate of the refining agent is controlled by the rotational speed of the feeding gear.

[0012] Furthermore, the horizontal rotation of the column and the vertical movement of the crossbeam are both driven by a third motor.

[0013] Furthermore, the first motor mounted on the crossbeam drives the rotor to rotate via belt drive.

[0014] Furthermore, the rotor consists of two parts: a rotating rod and a nozzle.

[0015] Furthermore, the nozzle is fixed to the bottom of the rotating rod by a threaded connection. The refining agent and refining gas enter the aluminum alloy melt through the spray channel outlet and are broken and dispersed under the shearing and stirring action of the nozzle.

[0016] Furthermore, the aluminum alloy melt rotary jet purification device also includes a cooling component that uses compressed air as a cooling medium. The cooling component includes cooling pipes, and the outside of the cooling pipes is wrapped with heat insulation cotton.

[0017] Furthermore, the method for purifying aluminum alloy melt using the aforementioned aluminum alloy melt rotary jet purification device includes: introducing refining gas into the annular cavity through the air inlet, generating negative pressure by flowing out through the air outlet, drawing the refining agent into the guide pipe and into the jet channel together; and cooling the rotor by introducing compressed air into the rotor through the cooling assembly.

[0018] Furthermore, the refining agent is one or more of NaCl, KCl, MgCl2, Na3AlF6, and KF.

[0019] Furthermore, the amount of refining agent added is 0.1~1.0 wt.% of the mass of the aluminum alloy melt.

[0020] Furthermore, the refining gas is nitrogen or argon.

[0021] Furthermore, the number of baffles is 1 to 2, the rotor nozzle is lowered to 20 to 50 cm from the bottom of the aluminum alloy melt, and the refining agent addition rate is 5 to 20 g / s.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. The structure of the negative pressure assisted feeding device of the present invention includes an air inlet (for introducing refining gas) on the outer wall of the outer cylinder, communicating with the annular cavity, and air outlets (connected via air outlet channels in the inner cylinder) evenly distributed on the inner wall of the inner cylinder. The refining gas flows out from the air outlets, generating negative pressure that draws the refining agent into the guide pipe. Compared with existing siphon-type negative pressure assisted refining agent adding devices, the structure of the present invention allows for uniform circumferential gas injection, forming a regular and stable annular negative pressure region. The negative pressure generated by the evenly distributed air outlets smoothly introduces the refining agent into the guide pipe, and then into the rotor via the guide pipe, with a controllable path. The negative pressure formed by this method is uniform and stable, and the evenly distributed air outlets ensure uniform gas ejection from the annular cavity, avoiding local negative pressure fluctuations. This results in good continuity and no pulsation in the refining agent intake, improving the accuracy of refining agent addition. Furthermore, the refining gas and refining agent are premixed inside the cylinder before entering the rotor through the guide pipe. This prevents powder agglomeration and blockage, and ensures thorough mixing of the refining agent. The gas and refining agent are in full contact in the negative pressure section, which is beneficial for subsequent dispersion in the melt. Moreover, no external devices such as suction fans or vacuum pumps are required; the negative pressure generation, refining agent intake, and flow guidance functions are integrated into a single cylinder, saving space and facilitating assembly with rotors, cover plates, and other components, resulting in a compact structure. Simultaneously, the negative pressure can be precisely controlled by adjusting the inlet pressure and flow rate, thereby regulating the refining agent addition rate to adapt to different process requirements.

[0024] 2. The method of adding the refining agent has been improved from relying on the vortex entrainment on the surface of the aluminum alloy melt to direct spraying from the bottom of the rotor. This not only ensures that the refining agent can fully enter the interior of the aluminum alloy melt to exert its adsorption and purification effect, but also eliminates the need to subject the surface of the aluminum alloy melt to violent disturbance and vortex formation during the addition of the refining agent. This significantly improves the utilization efficiency of the refining agent and greatly reduces secondary hydrogen and oxygen absorption and aluminum alloy melt burn-off during the purification process.

[0025] 3. A feeding gear is installed below the hopper, enabling precise and controllable adjustment of the refining agent addition rate. A negative pressure auxiliary feeding device added below the refining agent addition unit features optimized design and constraints on the inlet, outlet, and spray channel area, as well as the refining gas volumetric flow rate, to eliminate pipeline pulse blockage and backflow of molten aluminum alloy at the nozzle caused by solid-gas ratio mismatch. This keeps feeding fluctuations and total addition errors at extremely low levels. While ensuring conveying stability, the synergistic optimization of rotor speed and gas flow rate significantly reduces batch-to-batch fluctuations in degassing efficiency.

[0026] 4. A passive insulation layer and an active cooling pipe were added inside the rotor, which significantly reduced the thermal impact of the high-temperature aluminum alloy melt on the refining agent in the injection channel during the purification process. This effectively prevented the refining agent from clogging the injection channel due to the temperature rise process, significantly improved the continuity of the refining process, and reduced the difficulty of cleaning and maintaining the equipment. Attached Figure Description

[0027] Figure 1 This is a three-dimensional structural diagram of an aluminum alloy melt rotary jet purification device proposed in this invention.

[0028] Figure 2 This is a three-dimensional structural diagram of the refining agent addition device.

[0029] Figure 3 This is a cross-sectional view of the hopper and feeding gear of the refining agent addition device.

[0030] Figure 4 This is a three-dimensional structural diagram of the negative pressure assisted feeding device.

[0031] Figure 5 This is a cross-sectional view of the negative pressure assisted feeding device.

[0032] Figure 6 This is a schematic diagram of the rotor's three-dimensional structure.

[0033] Figure 7 This is a cross-sectional view of the rotor.

[0034] Figure 8 This is a structural diagram of a double-layer blade nozzle.

[0035] In the diagram, 1 is the base, 2 is the column, 3 is the crossbeam, 4 is the rotor, 4-1 is the rotating rod, 4-1-1 is the stainless steel inner liner, 4-1-1-1 is the spray channel, 4-1-1-2 is the cooling pipe, 4-1-1-3 is the heat insulation cotton, 4-1-1-4 is the compressed air mixing chamber, 4-1-2 is the graphite sheath, 4-1-3 is the cooling air supply assembly, 4-2 is the nozzle, 4-2-1 is the upper disc, 4-2-2 is the upper blade, 4-2-3 is the lower disc, and 4-2-4 is... The lower blades are: 5 is the first motor, 6 is the negative pressure auxiliary feeding device, 6-1 is the negative pressure generating unit, 6-2 is the diversion pipe, 6-1-1 is the outer cylinder, 6-1-2 is the inner cylinder, 6-1-3 is the annular cavity, 6-1-4 is the air inlet, 6-1-5 is the air outlet, 6-1-6 is the air outlet channel, 7 is the cover plate, 8 is the baffle, 9 is the refining agent adding device, 9-1 is the hopper, 9-2 is the second motor, 9-3 is the feeding gearbox, 9-4 is the feeding gear, and 10 is the transmission belt. Detailed Implementation

[0036] The technical solution of the present invention will be further described in detail below with reference to embodiments of the present invention. The described embodiments are merely examples and are not intended to limit the present invention.

[0037] like Figure 1As shown, an aluminum alloy melt rotary jet purification device includes a base 1. A horizontally rotatable column 2 is connected to the base 1; a crossbeam 3 is connected to the column 2, one end of which is connected to the column 2 and can move up and down along a track set on the column, and the other end is connected to a rotor 4. A first motor 5 for driving the rotor to rotate is installed in the middle. During the aluminum alloy melt purification process, the position of the rotor immersed in the aluminum alloy melt is adjusted by the horizontal rotation of the column 2 and the up and down movement of the crossbeam 3. The upper end of the rotor 4 is connected to the lower end of a negative pressure auxiliary feeding device 6, and a circular cover plate 7 is installed thereon. The center of the cover plate has a circular hole for assembly and connection with the rotor. Baffles 8 are installed below the cover plate; the number of baffles is 1 to 2. The upper end of the negative pressure auxiliary feeding device 6 is connected to a refining agent adding device 9.

[0038] Furthermore, the first motor 5 mounted on the crossbeam drives the rotor 4 to rotate via the transmission belt 10.

[0039] Furthermore, such as Figure 2 and Figure 3 As shown, the refining agent adding device 9 includes a hopper 9-1, a feeding gear 9-4 located at the hopper outlet and disposed in the feeding gearbox 9-3, and a second motor 9-2 for driving the feeding gear to rotate. When the refining agent adding device is working, the refining agent falls from the hopper 9-1 into the tooth gap of the feeding gear 9-4 under its own gravity, and is fed into the negative pressure auxiliary feeding device 6 below under the rotation drive of the feeding gear 9-4. The feeding rate of the refining agent is controlled by the rotation speed of the feeding gear.

[0040] Furthermore, the horizontal rotation of the column 2 and the vertical movement of the beam 3 are both driven by a third motor.

[0041] Furthermore, such as Figure 4 and Figure 5As shown, the negative pressure assisted feeding device 6 consists of an upper negative pressure generating unit 6-1 and a lower drainage pipe 6-2. The negative pressure generating unit 6-1 consists of an outer cylinder 6-1-1 and an inner cylinder 6-1-2, with an annular cavity 6-1-3 between the outer cylinder 6-1-1 and the inner cylinder 6-1-2. The outer wall of the outer cylinder 6-1-1 is provided with an air inlet 6-1-4 communicating with the annular cavity 6-1-3, and the inner wall of the inner cylinder is evenly distributed with multiple air outlets 6-1-5. Each air outlet 6-1-5 is connected to the annular cavity 6-1-3 through an air outlet channel 6-1-6 provided in the inner cylinder, and the area of ​​the air outlet channel 6-1-6 is the same as that of the air outlet 6-1-5. During operation, the refining gas is blown in through the inlet 6-1-4 and flows successively through the annular cavity 6-1-3 and the outlet channel 6-1-6 before exiting through the outlet 6-1-5 from the inner wall of the inner cylinder. The total area of ​​the outlet 6-1-5 is designed to be much smaller than the areas of the inlet 6-1-4 and the annular cavity 6-1-3. The refining gas is in a stable pressure state in the annular cavity 6-1-3 and is ejected at high speed from the narrow outlet 6-1-5 through the outlet channel 6-1-6. Utilizing the wall adhesion effect, it adheres to the inner wall of the inner cylinder and flows. According to Bernoulli's theorem, the pressure will decrease significantly, thereby generating a negative pressure near the outlet 6-1-5. This negative pressure can draw the refining agent falling from the refining agent addition device 9 into the guide pipe 6-2 and then enter the injection channel 4-1-1-1 inside the rotor 4 through the guide pipe 6-2.

[0042] Furthermore, such as Figure 6 and Figure 7 As shown, the rotor 4 consists of two parts: a rotating rod 4-1 and a nozzle 4-2.

[0043] Furthermore, the nozzle 4-2 is fixed to the bottom of the rotating rod 4-1 by a threaded connection. The refining agent and refining gas enter the aluminum alloy melt through the spray channel outlet opened at the bottom of the nozzle, and are broken and dispersed under the shearing and stirring action of the nozzle.

[0044] The nozzle 4-2 of the present invention can adopt an existing single-layer inclined blade structure. Furthermore, in a preferred embodiment, the nozzle 4-2 used in the present invention has a double-layer structure, such as... Figure 8 As shown, it consists of an upper disk 4-2-1, an upper blade 4-2-2, a lower disk 4-2-3, and a lower blade 4-2-4.

[0045] Both the upper and lower discs have a central hole, and their edges are machined with multiple semi-circular grooves. The upper blades are evenly distributed circumferentially below the upper disc, while the lower disc is located below the upper blades, with its blades also evenly distributed circumferentially below it. The upper and lower blades are inclined at a certain angle to the vertical, and their inclination directions are opposite. Viewed from above, when the nozzle rotates clockwise, the upper blades incline downwards to the right, and the lower blades incline downwards to the left; conversely, when the nozzle rotates counterclockwise, the inclination directions of the two blades are reversed.

[0046] Based on the above design, during nozzle rotation, the upper blades generate a downward axial force, and the lower blades generate an upward axial force. Together with the semi-circular groove (which exerts a horizontal circumferential shear force on the surrounding melt during high-speed rotation), this forms a compression-shear zone between the upper and lower blades. The aluminum alloy melt flowing in opposite directions converges and collides within the space between the upper and lower blades. Within this enclosed area, the aluminum alloy melt is repeatedly compressed and stretched. Refining gases and refining agents, subjected to compression and shearing in the compression-shear zone between the blades, are rapidly broken into a cluster of extremely small and evenly distributed dispersed bubbles, significantly increasing the gas-liquid contact area and thus achieving better refining results. Furthermore, the aforementioned compression-shear action is limited to the annular space between the upper and lower blades, preventing significant disturbance to the entire aluminum alloy melt and reducing oxidation and burn-off. In contrast, existing single-layer blades or multi-layer blades tilted in the same direction, regardless of the blade tilt angle, generate a dominant thrust flow in one direction (such as simply downward or upward) in the axial direction. The aluminum alloy melt lacks a directional opposing extrusion effect, resulting in limited bubble breakage efficiency and difficulty in achieving bubble homogenization. Preferably, the angle between the lower blade and the vertical direction is smaller than that between the upper blade and the vertical direction, so that the upper blade generates a larger downward axial force. The overall flow field in the extrusion zone exhibits a downward dominant flow direction, thereby avoiding liquid surface turbulence and reducing the oxidation and burning loss of the melt.

[0047] Furthermore, the rotating rod 4-1 consists of a stainless steel inner liner 4-1-1 and an outer graphite sheath 4-1-2. A cooling air supply assembly 4-1-3 is installed at the top of the rotating rod, and the cooling air supply assembly 4-1-3 is provided with a compressed air inlet and a compressed air outlet. The stainless steel inner liner 4-1-1 contains a refining agent spraying channel 4-1-1-1 located in the center, cooling pipes 4-1-1-2 that are evenly distributed around the spraying channel 4-1-1-1 and pass compressed air through them, and heat insulation cotton 4-1-1-3 that wraps around the cooling pipes 4-1-1-2. During the purification process of the aluminum alloy melt, compressed air is passed through the cooling pipes for heat dissipation. Combining the passive heat protection of the heat insulation cotton and the active heat dissipation of the compressed air, effective cooling of the internal spraying channel can be achieved. The cooling pipes 4-1-1-2 are two pairs of heat-resistant steel hollow round tubes, with the two pipes serving as the air inlet and outlet pipes, respectively. The air inlet pipe and the air outlet pipe are respectively connected to the air inlet and air outlet of the cooling air supply assembly at the top of the rotating rod. When the device is working, compressed air flows into the air inlet pipe through the compressed air inlet of the cooling air supply assembly 4-1-3, flows through the air inlet pipe to the compressed air mixing chamber 4-1-1-4 set at the bottom of the rotating rod, and then flows back to the top of the rotating rod through the air outlet pipe. Finally, it flows out through the compressed air outlet of the cooling air supply assembly 4-1-3.

[0048] In the rotary blowing purification process of aluminum alloy melt of this invention, the feeding and conveying of the refining agent involves the coupling of gas dynamics, particle rheology, and molten pool dynamics. Process parameters such as gas flow rate, feeding rate, and channel geometry are related to negative pressure generation, solid-gas carryover, and melt back pressure, forming a complex system. Traditional parameter design methods based on experience are prone to various problems, such as pipe blockage due to excessive feeding, insufficient gas flow rate leading to insufficient negative pressure, and powder softening and blockage due to slightly higher temperatures. In addition, there is a correlation between degassing efficiency, metal loss, and feeding stability; optimizing one objective often leads to a decrease in other indicators. Therefore, it is necessary to find a comprehensive process window that balances efficiency, stability, and cost at the intersection of multiple physical constraints through systematic optimization design, thereby ensuring the reliability of continuous production and the consistency of product quality.

[0049] This invention analyzes multiple nonlinear relationships in the injection process. First, the gas jet velocity at the outlet exhibits a square-law relationship with the negative pressure; changes in area or flow rate cause significant changes in negative pressure. Second, the gas-solid two-phase transport requires a solid-gas ratio below the critical value. Once the upper limit is exceeded, the gas-solid two-phase flow instantly transforms from a solid suspension state to a high-resistivity plug flow, leading to an exponential increase in pipeline pressure drop. Third, the refining agent is a mixture of multi-component chlorofluorocarbon salts, which softens near the low eutectic point under the radiant heat of the molten aluminum alloy, increasing the interparticle forces and causing the feeding rate to deviate from a linear relationship with the gear speed. Furthermore, the melt pressure pulsations generated by rotor rotation may propagate along the pipeline, coupling with the upstream suction process at fluid / mechanical frequencies, resulting in oscillations in the feeding behavior. Therefore, the aforementioned nonlinear couplings and threshold effects jointly determine the system's high sensitivity to parameter deviations and the concealment of faults.

[0050] Based on the above problems, this invention proposes an optimized design method for the aforementioned device, which includes first establishing relevant constraints, specifically as follows:

[0051] 1) For the negative pressure generating unit, it is necessary to ensure that the gas generates a sufficient negative pressure value when it flows out of the outlet. This negative pressure value is necessary to ensure that the refining agent particles are drawn into the guide pipe from the refining agent adding device and that the refining agent particles have a certain initial velocity.

[0052] 2) The average velocity of the airflow in the injection channel must be higher than a certain critical value, at least greater than the maximum settling velocity of the refining agent particles in the airflow (initial velocity + velocity generated by gravity), in order to avoid the refining agent particles from clogging the injection channel.

[0053] 3) The gas-solid ratio in the injection channel must meet reasonable conditions. If the refining agent addition rate is too high, it will cause plunger flow or dune flow to form in the pipeline, causing pressure fluctuations or even blockage. If the addition amount is too low, it will prolong the refining time, reduce efficiency, and increase energy consumption costs.

[0054] 4) The ratio of the inlet area to the outlet area needs to meet certain conditions. If the area design is unreasonable, the flow velocity at the inlet will be too high, resulting in pressure loss and reducing the total pressure reaching the outlet, thereby reducing the negative pressure.

[0055] Based on the above constraints, experimental tests were conducted to obtain the actual effects under different data, the main influencing factors were analyzed, and the results were integrated to obtain the conditions for stable delivery of the refining agent:

[0056]

[0057] In the formula, This represents the total area of ​​the air outlet (m²). The volumetric flow rate of refining gas is (m³ / s). The minimum required negative pressure (which can be obtained from actual measurements, approximately 13.5 Pa) is required. The density of the refining gas is given (nitrogen is taken as 1.13 kg / m³). This is the minimum flow velocity of the refining gas at the outlet (7~14 m / s, obtained from actual measurements). The area of ​​the jetting channel (m²) is the area of ​​the jetting channel. For safety margin, a value of 1.5 to 2.5 is used. The free settling velocity (m / s) of the refining agent particles in a stationary gas is determined by the particle size and density and can be obtained by actual measurement, ranging from 0.5 to 2.0 m / s. Refining agent addition rate (kg / s) The maximum permissible solid-to-gas ratio (mass ratio, the value of which is 6 in this invention) is given. The area of ​​the air inlet is (m²).

[0058] In practical applications, the units used for each parameter in the engineering process are converted to the SI units of the above-mentioned constraints. First, based on the refining time and the amount of refining agent added, the optimized refining agent addition rate is obtained. Then, based on formula (3), the minimum refining gas flow rate is determined. Then, based on the measured free settling velocity of the refining agent particles in the static gas, the maximum allowable area of ​​the injection channel is determined using formula (2). Then, the maximum allowable total area of ​​the gas inlet is calculated using formula (1). Finally, the inlet area is determined according to formula (4). After the calculation is completed, it is converted into the unit used in the actual project.

[0059] The design method described in this invention uses physical constraint equations as its core framework, transforming empirical design methods into quantitative boundary condition solving methods. Starting from the fundamental equations of gas-solid two-phase flow, it establishes constraint relationships centered on the upper limit of the solid-gas ratio, the anti-settlement flow velocity in the pipeline, and the negative pressure requirement. It combines area matching with flow rate-feeding rate to avoid multiple inefficient trial-and-error adjustments. By transforming the multivariate coupled problem into a subproblem that can be calculated step by step, the amount of experimental data required is significantly reduced.

[0060] Through the above-described optimized design, this solution eliminates pipeline pulse blockage and backflow of molten aluminum alloy at the nozzle caused by solid-gas ratio mismatch, keeping feeding fluctuations and total addition errors to extremely low levels. While ensuring conveying stability, the synergistic optimization of rotor speed and gas flow rate significantly reduces batch-to-batch fluctuations in degassing efficiency. Quantitative matching of flow channel geometric parameters maximizes negative pressure formation efficiency, reducing refining gas consumption and molten aluminum alloy temperature drop while maintaining the same degassing effect. This achieves highly stable, efficient, and low-cost operation of the molten aluminum alloy refining process.

[0061] This invention also discloses a method for purifying molten aluminum alloy by rotary blowing based on the above-mentioned device. The rotor nozzle descends to a position 20-50 cm from the bottom of the molten aluminum alloy. Refining gas is introduced into the internal blowing channel of the rotor through the air inlet of the negative pressure assisted feeding device. The negative pressure generated by the refining gas flowing out of the outlet draws the refining agent falling from the refining agent addition device into the guide pipe, and then into the internal blowing channel of the rotor through the guide pipe. Compressed air is introduced into the rotor through the cooling assembly for cooling. The refining agent can be one or more of NaCl, KCl, MgCl2, Na3AlF6, and KF, with an addition amount of 0.1-1.0 wt.% of the molten aluminum alloy. The refining gas is nitrogen or argon, and the refining agent addition rate is 5-20 g / s.

[0062] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A rotary jet purification device for molten aluminum alloy, characterized in that, Includes a base; a horizontally rotatable column is connected to the base; a crossbeam is connected to the column, one end of the crossbeam is connected to the column, and the other end is connected to the rotor; the crossbeam can move up and down along a track set on the column, and a first motor for driving the rotor to rotate is installed in the middle of the crossbeam. The upper end of the rotor is connected to the lower end of the negative pressure auxiliary feeding device, and a cover plate is also installed on the upper end of the rotor; the cover plate has a circular hole in the center for assembly and connection with the rotor, and a baffle is installed below the cover plate; the upper end of the negative pressure auxiliary feeding device is connected to the refining agent addition device. The negative pressure assisted feeding device includes an upper negative pressure generating unit and a lower guide pipe. The upper end of the negative pressure generating unit is connected to the refining agent adding device, including an outer cylinder and an inner cylinder. There is an annular cavity between the outer cylinder and the inner cylinder. An air inlet communicating with the annular cavity is provided on the outer wall of the outer cylinder. Air outlets are evenly distributed on the inner wall of the inner cylinder. The air outlets are connected to the annular cavity through an air outlet channel provided in the inner cylinder. The refining gas is blown in through the air inlet and flows through the annular cavity and the air outlet channel in succession. It is blown out from the inner wall of the inner cylinder through the air outlet. The area of ​​the air inlet is larger than the total area of ​​the air outlet. The negative pressure generated by the refining gas flowing out through the air outlet will draw the refining agent falling from the refining agent adding device into the guide pipe and enter the spray channel inside the rotor through the guide pipe. The refining agent addition device includes a hopper, a feeding gear located at the outlet of the hopper, and a second motor for driving the feeding gear to rotate. The feeding rate of the refining agent is controlled by the rotational speed of the feeding gear.

2. The aluminum alloy melt rotary jet purification device according to claim 1, characterized in that, The horizontal rotation of the column and the vertical movement of the crossbeam are both driven by a third motor.

3. The aluminum alloy melt rotary jet purification device according to claim 2, characterized in that, The first motor, mounted on the crossbeam, drives the rotor to rotate via belt drive.

4. The aluminum alloy melt rotary jet purification device according to claim 3, characterized in that, The rotor consists of two parts: a rotating rod and a nozzle.

5. The aluminum alloy melt rotary jet purification device according to claim 4, characterized in that, The nozzle is fixed to the bottom of the rotating rod by a threaded connection. The refining agent and refining gas enter the aluminum alloy melt through the spray channel outlet and are broken and dispersed under the shearing and stirring action of the nozzle.

6. The aluminum alloy melt rotary jet purification device according to claim 5, characterized in that, The aluminum alloy melt rotary jet purification device also includes a cooling component that uses compressed air as a cooling medium. The cooling component includes cooling pipes, and the outside of the cooling pipes is wrapped with heat insulation cotton.

7. A method for purifying aluminum alloy melt using the rotary jet cleaning device for aluminum alloy melt as described in claim 6, characterized in that, include: The refining gas enters the annular cavity through the inlet and flows out through the outlet, generating negative pressure that draws the refining agent into the guide pipe and into the injection channel together. Compressed air is introduced into the rotor through a cooling assembly for cooling.

8. The method for purifying aluminum alloy melt according to claim 7, characterized in that, The refining agent is one or more of NaCl, KCl, MgCl2, Na3AlF6, and KF.

9. The method for purifying aluminum alloy melt according to claim 8, characterized in that, The amount of refining agent added is 0.1~1.0 wt.% of the mass of the aluminum alloy melt.

10. The method for purifying aluminum alloy melt according to claim 7, characterized in that, The refining gas is nitrogen or argon.

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