A purification method for recycled aluminum melt used in automobile wheels

Abstract

A purification method for recycled aluminum melt used in automobile wheels, including nitrogen degassing at the bottom layer of a porous plug ladle with a porous plug ladle located below and argon degassing by a rotor degasser at the upper part. The nitrogen degassing device at the bottom layer of the porous plug ladle includes three porous plugs distributed at 120°. The depth of the degassing rotor inserted into the aluminum melt is 30 cm - 70 cm below the aluminum liquid surface. The argon degassing device of the upper rotor degasser includes a degassing rotor with a depth of 30 cm - 70 cm inserted into the aluminum melt. The temperature of the recycled aluminum melt is controlled at 740°C - 760°C. The present invention has good degassing and slag removal effects, high purification efficiency, energy saving, and environmental protection.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and specifically relates to a purification method for recycled aluminum melt used for automobile wheels. Background Art

[0002] Due to the characteristics of low density, high strength, good plasticity, excellent thermal conductivity, electrical conductivity, corrosion resistance, etc., aluminum alloys are widely used in the fields of aviation, aerospace, automotive transportation, construction, medical treatment, etc. With the development of the economic society, the social demand for aluminum alloys is increasing day by day, and the consumption of aluminum alloys is also increasing year by year, becoming the main metal material at present. However, with the increasing pressure of environmental protection and energy consumption reduction, aluminum alloys are also facing pressure from the aspects of environment and energy consumption.

[0003] The production process of aluminum alloys mainly includes steps such as bauxite mining, alumina electrolysis, adjustment of alloying components of primary aluminum melt, and aluminum alloy ingots. According to the research results of literature, every 1 ton of bauxite mined will consume 5 tons of mineral deposits and damage 1.314 m2 of vegetation. Producing 1 ton of alumina will generate 1 ton of red mud. During the electrolysis process of alumina, the power consumption is about 14,000 KW / h, generating 18 Kg of solid waste and 25 Kg of hazardous waste. According to the statistics of the International Aluminum Institute: In 2018, the global demand for aluminum has reached 95 million tons, and 64 million tons of the demand needs to be met by the production of bauxite ore. Given the high energy consumption and high pollution generated during the production process of aluminum alloys, this will undoubtedly seriously hinder the application process of aluminum alloys and bring great pressure to human environmental protection.

[0004] Facing the pressure of energy consumption and environmental protection brought by the production process of primary aluminum, domestic scientific research workers are paying more and more attention to the recycling and reuse of aluminum alloys. Recycling waste aluminum will save 14 m3 of water resources, 3.4 t of standard coal per ton compared with the production of primary aluminum. The total energy consumption drops by 20 times, the solid waste is reduced by 20 t, and the greenhouse gas emissions are reduced by 24 times. Therefore, the research and application of recycled aluminum will become an effective way to solve the high pollution and high energy consumption of aluminum alloys. In 2018, the usage amount of recycled aluminum reached 31 million tons. According to the prediction of the International Aluminum Institute, by 2050, the global demand for aluminum will increase by 80%. This means that the supply of recycled aluminum will continue to increase, and the expected demand will be as high as 70 million tons by 2050.

[0005] Aluminum is the metal with the highest recycling efficiency. Aluminum can be recycled repeatedly and almost infinitely, thus becoming the most reliable and efficient sustainable material. The International Aluminum Institute analyzes the material flow of aluminum every year through a comprehensive global database and an originally developed logistics analysis system. It can trace aluminum waste according to aluminum products, quality, form, and regional categories, including the entire process from the source of waste generation to end consumption. Compared with producing primary aluminum from bauxite, the energy required to produce recycled aluminum is reduced by 95%, effectively reducing and avoiding pollutant emissions including greenhouse gases. 75% of the world's aluminum is still in use. Of the nearly 1.5 billion tons of aluminum produced globally to date, approximately 75% is still in use in various applications.

[0006] Transportation is the most important field for aluminum recycling. In terms of both the recycling volume and the recycling rate, the transportation industry is the most important field for waste aluminum recycling. This industry recycles the largest amount of waste aluminum, with a recycling volume of 9 million tons by weight and a recycling rate of 86%. The recycling and application of aluminum products in the transportation industry will become a key area of research in the future aluminum recycling industry. The application of recycled aluminum in the automotive industry will promote the process of aluminum recycling in transportation. As the automotive component with the largest amount of aluminum used currently, the application of recycled aluminum in automotive wheels will become the focus of research.

[0007] With the increasing demand for recycled aluminum and the expanding application scope, scraps generated during the manufacturing process of aluminum alloys, scrapped automotive parts, used aluminum cans, old aluminum alloy doors and windows, etc. are recycled and re-prepared into new aluminum alloy products. Due to reasons such as the imperfect current management system for waste aluminum alloys, unclear classification of aluminum alloy recycling, immature technology of aluminum alloy recycling equipment, complex chemical composition of waste aluminum alloys, excessive impurity elements in waste aluminum, and difficult removal of accessories, most of the recycled aluminum is difficult to be applied to automotive wheels, resulting in the degradation and serious waste of resources. Secondly, as a safety component, automotive aluminum alloy wheels have strict requirements for the quality of recycled aluminum. Currently, after the recycled aluminum melt is treated by conventional refining, degassing, slag skimming and other purification processes, there are still tiny inclusions and gases inside the melt, which are difficult to meet the conditions required for the preparation of automotive parts, posing potential safety hazards. Therefore, it is necessary to invent a purification method for recycled aluminum melt for automotive wheels with good degassing and slag removal effects, high purification efficiency, energy saving, and environmental protection. Summary of the Invention

[0008] In view of this, the present invention aims to provide a purification method for recycled aluminum melt used in automobile wheels, which addresses the problems such as high hydrogen content inside the melt, large amount of fine slag, long degassing time, environmental pollution caused by using slag cleaning agents, and high treatment costs during the melt treatment process of recycled aluminum raw materials applied to automobile wheels. The invention proposes a purification method for recycled aluminum melt with good degassing and slag removal effects, high purification efficiency, energy conservation, and environmental protection. The purification method mainly includes the process parameters of nitrogen degassing with a bottom porous brick ladle and argon degassing with an upper rotor degasser. The present invention mainly combines bottom porous brick degassing and upper rotor degasser degassing and purification. By process parameters such as the type of inert gas for aluminum melt, gas position distribution, melt temperature, inert gas flow rate, inert gas pressure, inert degassing time, and degassing rotor speed, the role of the purification method in improving the quality of recycled aluminum melt is maximally exerted, and finally the effects of reducing the internal gas content, reducing the content of fine slag, shortening the degassing time, and reducing the consumption of inert gas in the recycled aluminum melt are achieved. The present invention has remarkable effects on improving the quality of recycled aluminum melt, reducing internal defects, and enhancing degassing efficiency. It is a purification method for recycled aluminum melt with good degassing and slag removal effects, high purification efficiency, energy conservation, and environmental protection.

[0009] To achieve the above object, the technical solution of the present invention is realized as follows:

[0010] A purification method for recycled aluminum melt used in automobile wheels, in which nitrogen degassing with a bottom porous brick ladle and argon degassing with an upper rotor degasser are mainly related to the quality of recycled aluminum melt. Therefore, process parameters such as the type of inert gas for recycled aluminum melt, gas position distribution, melt temperature, inert gas flow rate, inert gas pressure, inert degassing time, and degassing rotor speed are the key to the technical solution.

[0011] The requirements for process parameters such as the type of inert gas used for degassing the recycled aluminum melt, gas position distribution, melt temperature, inert gas flow rate, inert gas pressure, inert degassing time, and degassing rotor speed are as follows:

[0012] First: Since recycled aluminum melt uses recycled waste wheels, scraps, aluminum chips, electric wires and other waste materials as raw materials, it is difficult to clean up the slag such as dust, sludge, oil stains, crystal salts, fiber powder, inorganic coatings, rubber, and glass existing inside. Inevitably, the above-mentioned slag will exist in the molten recycled aluminum melt. Since the slag is distributed inside the aluminum melt after melting at high temperature, a purification method of nitrogen degassing at the bottom layer of the bottom porous brick ladle and argon degassing with an upper rotor degasser is adopted. During the degassing and purification process, three porous bricks should be used for the bottom porous brick and distributed at 120°, and the depth of the degassing rotor extending into the aluminum melt is 30 cm - 70 cm below the aluminum liquid surface.

[0013] Second: The slag inclusions, gases, and melt viscosity in the recycled aluminum melt will all change with the temperature of the aluminum liquid. To ensure the purification effects of nitrogen degassing at the lower part of the porous plug ladle and argon degassing by the upper rotor degasser, it is necessary to comprehensively consider factors such as the solubility change of gases in the aluminum melt, the floating speed of slag inclusions, and the viscosity of the recycled aluminum melt. The temperature of the recycled aluminum melt is controlled at 740°C - 760°C.

[0014] Third: Due to the mixed types of raw materials in recycled aluminum, it is difficult to completely remove the oil stains, dirt, and impurities on the surface of recycled waste materials. As a result, there are problems such as complex types of impurities, different particle sizes, and differences in wettability with the aluminum melt surface in the melted recycled aluminum melt. The degassing process of the lower porous plug ladle is carried out in two stages. In the first stage, the nitrogen gas flow rate is 20 L / min - 35 L / min, the gas pressure is 0.3 MPa - 0.55 MPa, and the degassing time is 120 - 240 s. In the second stage, the nitrogen gas flow rate is 10 L / min - 20 L / min, the gas pressure is 0.2 MPa - 0.35 MPa, and the degassing time is 180 - 300 s. The degassing process of the upper rotor degasser is carried out in two stages. In the first stage, the argon gas flow rate is 30 L / min - 45 L / min, the rotor speed is 400 rpm - 550 rpm, and the degassing time is 180 - 280 s. In the second stage, the argon gas flow rate is 40 L / min - 65 L / min, the rotor speed is 300 rpm - 420 rpm, and the degassing time is 200 - 360 s.

[0015] The substantial features of the present invention are:

[0016] Currently, the classification of waste aluminum alloys is not clear, the raw materials are mixed, the level of pretreatment technology is low, and there are too many impurity elements in waste aluminum, resulting in most recycled aluminum being difficult to be applied to automotive wheels. Secondly, as safety components, automotive aluminum alloy wheels have strict requirements for the quality of recycled aluminum. Thirdly, it is difficult to effectively remove the slag inclusions such as dust, sludge, oil stains, crystal salts, fiber powder, inorganic coatings, rubber, and glass in the raw materials of recycled aluminum in the aluminum melt, which severely restricts the application of recycled aluminum in automotive wheels.

[0017] At present, in the aluminum alloy industry, methods such as rotor degassing and purification, porous plug degassing and purification, and slag cleaning agents are generally commonly used for melt degassing and purification. Due to the complex composition and small particle size of the slag in the recycled aluminum raw materials, the slag inside after recycling and melting is diffusely distributed and has a large bonding force with the aluminum melt. It is difficult to remove it completely through conventional degassing and purification means. In the process of degassing and purification by a rotor degassing machine, the inert gas is sheared into fine bubbles by the rotation of the rotor and the melt flow formed by the rotation of the rotor, so that the slag and gas in the horizontal direction of the melt are adsorbed on the surface of the inert body, and finally the effect of slag and gas removal is achieved. However, it is difficult to achieve a good cleaning and purification effect on the high-density slag at the bottom of the melt and the slag in the vertical direction. Similarly, porous plug degassing is to arrange a porous plug at the bottom of the ladle, and the inert gas enters the melt through the porous plug. In the vertical direction of the melt, the inert bubbles adsorb the slag and harmful gases to form the effect of degassing and purification. Since it takes time for the inert bubbles in the melt to float up and the distribution of the inert gas is uneven, the cleaning effect on the slag and harmful gases in the horizontal direction is not ideal. Therefore, the current degassing and purification methods have drawbacks in the application of recycled aluminum in safety components such as automotive wheels, and the purification effect on the aluminum melt is insufficient, seriously restricting the application scope of recycled aluminum.

[0018] The present invention adopts the method of nitrogen degassing by a lower porous plug and argon degassing by an upper rotor degassing machine, combining the effects of rotor degassing and porous plug degassing. During the degassing process, factors such as the size, distribution, dispersion degree, and density of the slag and gas defects inside the recycled aluminum melt are comprehensively considered, and the all-round degassing of the recycled aluminum melt is realized by the methods of lower porous plug and upper rotor degassing. The degassing of three lower porous plugs distributed at 120° can ensure that the inert gas introduced from the lower part fully covers the entire bottom of the melt and can be fully distributed in the vertical direction. Especially for the positions where the inert gas diffused by the lower rotor degassing cannot reach (such as the edge part), the slag and gas at the bottom of the melt can be adsorbed on the surface of the inert gas and float up with the inert gas, and it has a good cleaning effect on the slag and gas in the vertical direction of the melt; during the rotor degassing process, the degassing rotor extends 30 cm - 70 cm below the aluminum melt surface. As the rotor rotates, a melt turbulence can be formed on the melt plane where the rotor is located, and there is also a part of the melt flow in the vertical direction. While capturing the slag and gas in the horizontal direction of the melt, it promotes the floating of the inert gas introduced from the lower part. This is the biggest difference between the present invention and other degassing and purification methods.

[0019] In the present invention, the positions where high-purity nitrogen and high-purity argon enter the aluminum melt during the degassing process are different. High-purity nitrogen is introduced into the interior of the aluminum melt through a porous plug at the bottom. During the degassing process, it mainly floats upward from the bottom to adsorb slag inclusions and harmful gases. High-purity argon is introduced into the melt from the upper part through a rotor degasser to remove slag inclusions and harmful gases in the horizontal direction. The position where the gas is introduced into the melt is also different from other degassing methods. During the degassing and purification process of the aluminum melt, fine inert bubbles combine with slag inclusions and gases in the melt, and under the buoyancy of the gas, they float from the interior of the melt to the surface of the melt, and then the slag inclusions and gases are removed by skimming. The present invention fully considers the characteristics of the two gases and comprehensively considers factors such as the floating speed of the two inert gases in the melt, so that the inert gas can combine with slag inclusions and gases to the greatest extent, improving the melt purification effect and purification efficiency.

[0020] The degassing and purification temperature of the recycled aluminum melt in the present invention is different from that of the normal aluminum alloy degassing process. After melting normal aluminum ingots for aluminum alloy wheels, the temperature during the degassing process is generally relatively low, about 700°C - 730°C. Since the types of slag inclusions in normal aluminum ingots are relatively single and the types of harmful gases are also single, and the melt has little loss and saves energy when controlled at this temperature. The recycled aluminum melt contains products after high-temperature melting reactions such as oil stains, dust, fibers, and paint, and harmful gases generated by volatile substances also exist in the melt. These slag inclusions and harmful gases seriously affect the viscosity of the melt, and have a significant impact on the flow of the melt, the floating of inert gases, and the solubility of harmful gases during the degassing and purification process. The slag inclusions and harmful gases inside the melt can ensure that the viscosity of the melt is suitable for degassing and purification at the temperature specified in the present invention, and the minimum solubility of harmful gases is beneficial to the escape of harmful gases from the melt. Secondly, during the floating process of inert bubbles adsorbing slag inclusions and harmful gases during the degassing and purification process, factors such as melt viscosity, contact angle between the melt and inert gas, and melt fluidity need to be comprehensively considered. Therefore, the degassing and purification of recycled aluminum melt needs to be carried out at a higher temperature.

[0021] In the present invention, the control of gas parameters in the lower and upper parts is different. The present invention comprehensively considers the types, sizes, gas solubilities, distributions of suspended particles inside the recycled aluminum melt, as well as the influence on the floating of inert gas during the melt flow process. The degassing and purification process of the lower porous plug is carried out in two stages. In the first stage, the nitrogen gas flow rate is 20 L / min - 35 L / min, the gas pressure is 0.3 MPa - 0.55 MPa, and the degassing time is 120 - 240 s. In the second stage, the nitrogen gas flow rate is 10 L / min - 20 L / min, the gas pressure is 0.2 MPa - 0.35 MPa, and the degassing time is 180 - 300 s. The degassing and purification process of the upper rotor is carried out in two stages. In the first stage, the argon gas flow rate is 30 L / min - 45 L / min, the rotor speed is 400 rpm - 550 rpm, and the degassing time is 180 - 280 s. In the second stage, the argon gas flow rate is 40 L / min - 65 L / min, the rotor speed is 300 rpm - 420 rpm, and the degassing time is 200 - 360 s. The degassing in the upper part and the degassing in the lower part are both carried out in two stages, which can fully ensure the formation of a good gas turbulent flow effect in the first stage of degassing and purification, promoting the full contact between the inert gas and the inclusions and gases inside the melt. In the second stage, it fully ensures the floating of the inert gas and the capture effect on the inclusions and harmful gases inside. The degassing and purification method in two stages makes full use of the characteristics of the inclusions and harmful gases inside the melt, as well as the characteristics of the dispersion, floating of the inert gas, and the flow of the melt in the vertical and horizontal directions during the degassing and purification process, maximizing the degassing effects of nitrogen and argon. At the same time, it can save gas consumption and avoid increasing costs and environmental pollution by using slag cleaning agents.

[0022] Compared with the prior art, the purification method of the recycled aluminum melt for automobile wheels described in the present invention has the following advantages:

[0023] At present, due to the mixed types of waste aluminum, the presence of paint on the surface, insufficient pretreatment, and excessive types of impurity elements, the quality of most recycled aluminum melts is relatively low. Secondly, inclusions such as dust, sludge, oil stains, crystal salts, fiber powder, inorganic coatings, rubber, and glass in the recycled aluminum raw materials are doped into the melt during the melting process to form various compounds, which are finely and diffusely dispersed inside the melt. At the same time, low-melting-point substances such as paint volatilize at high temperatures to generate harmful gases that dissolve in the aluminum liquid, thus seriously affecting the quality of the recycled aluminum melt and also posing a challenge to the degassing and purification methods. First of all, due to the complex composition of inclusions, small particle size, and the dispersion of harmful gases inside the melt in the recycled aluminum raw materials, the commonly used degassing methods at present are difficult to achieve good purification effects. At the same time, the existing degassing methods have drawbacks. The rotor degassing machine has good degassing effects on the inclusions and gases in the horizontal direction of the melt, but it is difficult to form good removal effects on the high-density inclusions at the bottom of the melt and the inclusions in the vertical direction. The permeable rotary degassing has good degassing effects on the inclusions and gases in the vertical direction of the melt, but due to the time required for the inert bubbles in the melt to float up and the uneven distribution of inert gases, the removal effects on the inclusions and gases in the horizontal direction are not ideal. Secondly, for the situation where there are various types of inclusions, small particles, uneven distribution, and diffuse distribution of harmful gases inside the melt in the commonly used degassing methods, methods such as increasing the gas flow rate, extending the degassing time, and replacing with higher-purity inert gases are often adopted, which seriously reduces the degassing efficiency, increases the degassing cost, and also causes losses to the service life of the degassing device. The present invention proposes a degassing and purification method for recycled aluminum melts with good degassing and slag removal effects, high purification efficiency, energy conservation, and environmental protection in view of the above problems.

[0024] 1) The present invention adopts the method of nitrogen degassing with a lower permeable brick and argon degassing with an upper rotor degassing machine, reasonably arranges the distribution of the permeable brick and the position of the rotor in the melt, can give full play to the degassing effects of the permeable brick and the rotor degassing machine, ensure that the inclusions inside the recycled aluminum melt are fully in contact with the inert gas, and at the same time has good degassing effects on the inclusions in the vertical direction and the horizontal direction. After taking the K mold to compare the inclusion ratio of the recycled aluminum melt treated by the degassing and purification method of the present invention and the conventional degassing method, the average K value of the melt treated by the conventional degassing method is about 0.35, and the average K value of the recycled aluminum melt treated by the degassing method of the present invention is about 0.05. It can be seen from this that the present invention has good purification effects on the inclusions inside the recycled aluminum melt.

[0025] 2) The present invention adopts a combined degassing and purification method of a lower porous plug and an upper rotor, which has a good effect on removing harmful gases inside the recycled aluminum melt. The inert gas in the present invention can be fully and evenly distributed inside the recycled aluminum melt, greatly increasing the probability of contact between the inert bubbles and the harmful gases. Secondly, the reasonable arrangement of the position where the inert gas is introduced can promote the flow of the melt and the floating of the inert bubbles, and can achieve the effect of efficient degassing. Comparing the degassing and purification effects of the conventional degassing method and the degassing method of the present invention, and analyzing the treated recycled aluminum melt according to the requirements of measuring density by reduced-pressure solidification, it can be obtained that the sampling density of the melt after conventional treatment is about 2.56 g / cm3, and the sampling density of the melt treated by the present invention is about 2.64 g / cm3. Therefore, the present invention has a good degassing and purification effect on the gases inside the recycled aluminum melt.

[0026] 3) Using the degassing method of the present invention can greatly improve the degassing and purification efficiency. The aluminum alloy melt mainly ensures the degassing and purification effect through the gas flow rate and the degassing time during the degassing and purification stage. Therefore, if the degassing time is long, it will seriously affect the degassing efficiency. The degassing and purification method in the present invention combines the method of degassing with a lower porous plug and an upper rotor, forming uniform inert bubbles in the vertical and horizontal directions in a short time, increasing the probability of contact between the inert gas and the inclusions and harmful gases, thereby improving the degassing and purification efficiency and saving the degassing cost. By comparing and analyzing the degassing time and gas consumption of the degassing and purification method of the present invention and the conventional degassing method, the degassing efficiency of the conventional degassing method is about 15.4 min / t, and the consumption of inert gas is 18.2 L / t. The degassing efficiency of the degassing method of the present invention is 11.4 min / t, and the consumption of inert gas is 14.3 L / t. Therefore, the present invention can achieve the effect of improving the degassing efficiency and saving the gas consumption.

[0027] 4) The porous plug ladle, inert gas, degassing machine, temperature-measuring thermocouple, etc. involved in the present invention are all conventional equipment and materials in the industry. The production processes of these equipment and materials are mature and stable, so they will not increase the melt degassing cost. Therefore, the present invention has the effects of being easy to implement, economical and practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0029] Figure 1 is a schematic diagram of a purification method for recycled aluminum melt for an automobile wheel hub according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0031] Next, the technical solutions of the present invention will be clearly and completely described with reference to the accompanying drawings and in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the scope of protection of the present invention.

[0032] Next, a purification method for recycled aluminum melt used for automobile wheels in an embodiment of the present invention will be described in conjunction with the embodiments.

[0033] Embodiment 1:

[0034] The embodiment of the present invention provides a degassing method for recycled aluminum melt used for automobile wheels. The degassing method mainly consists of degassing process parameters such as the flow rates of nitrogen gas at the lower part and argon gas at the upper part, gas pressure, degassing time, rotation speed, and melt standing time.

[0035] Put the recycled aluminum waste into the melting furnace, set parameters such as furnace temperature and furnace pressure according to the structure of the melting furnace and the manufacturer's operation manual. After waiting for all the waste in the furnace to melt into aluminum liquid, skim the slag on the surface of the aluminum liquid in the melting furnace to remove the floating slag on the surface of the aluminum liquid in the furnace, ensure that the surface of the aluminum liquid is clean, and then introduce the aluminum liquid into the porous plug ladle for melt degassing. Before introducing the aluminum liquid into the porous plug, it is necessary to ensure that the temperature of the aluminum liquid is above 740 °C. Transfer the porous plug ladle filled with aluminum melt to the degassing equipment for melt degassing. The degassing is mainly composed of nitrogen degassing through the porous plug at the lower part and argon degassing by the rotor at the upper part. Both nitrogen and argon are in high-purity state, and the degassing processes at the lower part and the upper part are carried out simultaneously. Measure the temperature of the aluminum melt in the ladle. When the temperature is at 740 ± 1 °C, start degassing. The control parameters of the porous plug ladle at the lower part are as follows: in the first stage, the nitrogen gas flow rate is 20 L / min, the gas pressure is 0.3 MPa, and the degassing time is 240 s; in the second stage, the nitrogen gas flow rate is 10 L / min, the gas pressure is 0.35 MPa, and the degassing time is 300 s. The control parameters of the rotor degassing process at the upper part are as follows: the rotor of the degassing machine extends 30 cm below the liquid level of the melt in the ladle. In the first stage, the argon gas flow rate is 30 L / min, the rotor speed is 400 rpm, and the degassing time is 280 s; in the second stage, the argon gas flow rate is 40 L / min, the rotor speed is 420 rpm, and the degassing time is 360 s. After the degassing processes at the lower part and the upper part are completed, the degassing process of the recycled aluminum melt is finally completed. Skim the floating slag on the surface of the aluminum melt in the ladle. Analyze the chemical composition, melt hydrogen content, and melt slag inclusion of the aluminum liquid in the ladle. After the test results are qualified, transfer it to the die-casting machine for the production of aluminum alloy wheels.

[0036] Embodiment 2:

[0037] An embodiment of the present invention provides a degassing method for recycled aluminum melt for automotive wheels. The degassing method mainly consists of degassing process parameters such as the flow rates of nitrogen gas at the lower part and argon gas at the upper part, gas pressure, degassing time, rotation speed, and melt standing time.

[0038] Put the recycled aluminum waste into the melting furnace, set parameters such as furnace temperature and furnace pressure according to the structure of the melting furnace and the manufacturer's operation manual. After waiting for all the waste in the furnace to melt into aluminum liquid, skim the aluminum liquid in the melting furnace to remove the floating slag on the surface of the aluminum liquid in the furnace, ensure that the surface of the aluminum liquid is clean, and then introduce the aluminum liquid into the porous plug ladle for melt degassing. Before introducing the aluminum liquid into the porous plug, it is necessary to ensure that the temperature of the aluminum liquid is above 750 °C. Transfer the porous plug ladle filled with aluminum melt to the degassing equipment for melt degassing. The degassing is mainly composed of combined degassing with nitrogen gas through the porous plug at the lower part and argon gas by the rotor at the upper part. Both nitrogen gas and argon gas are in high-purity state, and the degassing processes at the lower part and the upper part are carried out simultaneously. Measure the temperature of the aluminum melt in the ladle. When the temperature is at 750 ± 1 °C, start degassing. The control parameters for the porous plug ladle at the lower part are: in the first stage, the nitrogen gas flow rate is 25 L / min, the gas pressure is 0.35 MPa, and the degassing time is 200 s; in the second stage, the nitrogen gas flow rate is 14 L / min, the gas pressure is 0.30 MPa, and the degassing time is 240 s. The control parameters for the rotor degassing process at the upper part are: the rotor of the degassing machine extends 40 cm below the liquid level in the ladle. In the first stage, the argon gas flow rate is 35 L / min, the rotor rotation speed is 450 rpm, and the degassing time is 250 s; in the second stage, the argon gas flow rate is 50 L / min, the rotor rotation speed is 380 rpm, and the degassing time is 300 s. After the degassing processes at the lower part and the upper part are completed, the degassing process of the recycled aluminum melt is finally completed. Skim the floating slag on the surface of the aluminum melt in the ladle. Analyze the chemical composition, melt hydrogen content, and melt slag inclusion of the aluminum liquid in the ladle. After the test results are qualified, transfer it to the die-casting machine for the production of aluminum alloy wheels.

[0039] Example 3:

[0040] An embodiment of the present invention provides a degassing method for recycled aluminum melt for automotive wheels. The degassing method mainly consists of degassing process parameters such as the flow rates of nitrogen gas at the lower part and argon gas at the upper part, gas pressure, degassing time, rotation speed, and melt standing time.

[0041] Put the recycled aluminum waste into the melting furnace, and set parameters such as furnace temperature and furnace pressure according to the structure of the melting furnace and the manufacturer's operation manual. After waiting for all the waste in the furnace to melt into molten aluminum, skim the molten aluminum in the melting furnace to remove the floating slag on the surface of the molten aluminum in the furnace, ensure that the surface of the molten aluminum is clean, and pour the molten aluminum into the porous plug ladle to prepare for melt degassing. Before pouring the molten aluminum into the porous plug, it is necessary to ensure that the temperature of the molten aluminum is above 755 °C. Transfer the porous plug ladle filled with molten aluminum to the degassing equipment for melt degassing. The degassing is mainly composed of nitrogen degassing through the lower porous plug and argon degassing by the upper rotor. Both nitrogen and argon are in high-purity state, and the lower and upper degassing processes are carried out simultaneously. Measure the temperature of the molten aluminum in the ladle, and start degassing when the temperature is at 755 ± 1 °C. The control parameters of the lower porous plug ladle are as follows: in the first stage, the nitrogen gas flow rate is 30 L / min, the gas pressure is 0.45 MPa, and the degassing time is 160 s; in the second stage, the nitrogen gas flow rate is 18 L / min, the gas pressure is 0.25 MPa, and the degassing time is 320 s. The control parameters of the upper rotor degassing process are as follows: the rotor of the degassing machine extends 50 cm below the liquid level of the molten metal in the ladle. In the first stage, the argon gas flow rate is 40 L / min, the rotor speed is 500 rpm, and the degassing time is 210 s; in the second stage, the argon gas flow rate is 55 L / min, the rotor speed is 340 rpm, and the degassing time is 250 s. After the lower and upper degassing processes are completed, the degassing process of the recycled aluminum melt is finally completed. Skim the floating slag on the surface of the molten aluminum in the ladle. Analyze the chemical composition, melt hydrogen content, and melt slag inclusion of the molten aluminum in the ladle. After the test results are qualified, transfer it to the die-casting machine for the production of aluminum alloy wheels.

[0042] Example 4:

[0043] An embodiment of the present invention provides a method for degassing recycled aluminum melt for automotive wheels. The degassing method mainly consists of degassing process parameters such as the flow rate, gas pressure, degassing time, rotation speed, and melt standing time of nitrogen in the lower part and argon in the upper part.

[0044] Put the recycled aluminum waste into the melting furnace, and set parameters such as furnace temperature and furnace pressure according to the structure of the melting furnace and the manufacturer's operation manual. After waiting for all the waste in the furnace to melt into molten aluminum, skim the molten aluminum in the melting furnace to remove the floating slag on the surface of the molten aluminum in the furnace, ensure that the surface of the molten aluminum is clean, and then transfer the molten aluminum into the porous plug ladle to prepare for melt degassing. Before the molten aluminum is introduced into the porous plug, it is necessary to ensure that the temperature of the molten aluminum is above 760 °C. Transfer the porous plug ladle filled with molten aluminum to the degassing equipment for melt degassing. Degassing is mainly composed of nitrogen degassing through the lower porous plug and argon degassing by the upper rotor. Both nitrogen and argon are in high-purity state, and the lower and upper degassing processes are carried out simultaneously. Measure the temperature of the molten aluminum in the ladle, and start degassing when the temperature is at 760 ± 1 °C. The control parameters of the lower porous plug ladle are: in the first stage, the nitrogen gas flow rate is 35 L / min, the gas pressure is 0.55 MPa, and the degassing time is 120 s; in the second stage, the nitrogen gas flow rate is 20 L / min, the gas pressure is 0.35 MPa, and the degassing time is 180 s. The control parameters of the upper rotor degassing process are: the rotor of the degassing machine extends 70 cm below the liquid level of the molten metal in the ladle. In the first stage, the argon gas flow rate is 45 L / min, the rotor speed is 550 rpm, and the degassing time is 180 s; in the second stage, the argon gas flow rate is 65 L / min, the rotor speed is 300 rpm, and the degassing time is 200 s. After the lower and upper degassing processes are completed, the degassing process of the recycled aluminum melt is finally completed. Skim the floating slag on the surface of the molten aluminum in the ladle. Analyze the chemical composition, melt hydrogen content, and melt slag inclusion of the molten aluminum in the ladle. After the test results are qualified, transfer it to the die-casting machine for the production of aluminum alloy wheels.

[0045] Table 1 Statistical Table of K Value after Degassing of Recycled Aluminum Melt

[0046]

[0047] Table 2 Statistical Table of Density after Degassing of Recycled Aluminum Melt

[0048]

[0049] Table 3 Statistical Table of Degassing Process Efficiency and Gas Consumption of Recycled Aluminum Melt

[0050]

[0051] The K-value results after degassing and purifying the recycled aluminum melt are counted in Table 1 above. It can be seen from Table 1 that the conventional degassing method has a relatively poor slag removal effect on the recycled aluminum melt. The average K-value of the melt sample after degassing is 0.35, which has a large gap compared with the K-value of 0.05 after degassing the current normal aluminum melt. For Examples 1, 2, 3, and 4, the average K-value of the melt sample after degassing is 0.05, which is equivalent to the K-value level after degassing the normal aluminum melt and can be used subsequently. This shows that through the design of process parameters such as the type of inert gas in the recycled aluminum melt, the gas position distribution, the melt temperature, the inert gas flow rate, the inert gas pressure, the inert degassing time, and the degassing rotor speed, the present invention has a good purification effect on the inclusions in the recycled aluminum melt. The density results after degassing the recycled aluminum melt are counted in Table 2. It can be seen from Table 2 that the conventional degassing method has a relatively poor degassing effect on the recycled aluminum melt. The average density value of the melt sample after degassing is 2.56 g / cm 3 , which has a large gap compared with the density value of 2.64 g / cm 3 after degassing the current normal aluminum melt. For Examples 1, 2, 3, and 4, the average density value of the melt sample after degassing and purification is 2.64 g / cm 3 , which is equivalent to the density value level after degassing the normal aluminum melt and can be used subsequently. This shows that through the design of process parameters such as the type of inert gas in the recycled aluminum melt, the gas position distribution, the melt temperature, the inert gas flow rate, the inert gas pressure, the inert degassing time, and the degassing rotor speed, the present invention has a good degassing and purification effect on the recycled aluminum melt. Table 3 counts the efficiency and gas consumption during the degassing process of the recycled aluminum melt. It can be seen from Table 3 that for the conventional degassing method, the average levels of its efficiency and inert gas consumption are about 15.4 min / t and 18.2 L / t, while for Examples 1, 2, 3, and 4, the average levels of the efficiency and inert gas consumption of their degassing methods are about 11.4 min / t and 14.3 L / t. This shows that through the design of process parameters such as the type of inert gas in the recycled aluminum melt, the gas position distribution, the melt temperature, the inert gas flow rate, the inert gas pressure, the inert degassing time, and the degassing rotor speed, the degassing method of the present invention can achieve the effect of improving the degassing efficiency and saving the gas consumption.

[0052] Compared with the prior art, the purification method of the recycled aluminum melt for automobile wheels of the present invention has the following advantages:

[0053] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the protection scope of the present invention.

[0054] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0055] In the present invention, unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled", "fixed", etc. shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or a connection that allows mutual communication; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0056] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A purification method for recycled aluminum melt used in automobile wheels, characterized in that, it includes nitrogen degassing at the bottom layer of the porous plug ladle and argon degassing by a rotor at the upper part, which are arranged below and above the porous plug ladle. The nitrogen degassing device at the bottom layer of the porous plug ladle includes three sector-shaped porous plugs distributed at 120° so that the inert gas introduced from below can fully cover the entire bottom of the melt and have sufficient inert gas distribution in the vertical direction. The argon degassing device by the rotor at the upper part includes a degassing rotor extending into the aluminum melt to a depth of 30 cm - 70 cm below the aluminum liquid surface. The temperature of the recycled aluminum melt is controlled at 740°C - 760°C. The degassing process of the lower porous ladle is carried out in two stages. In the first stage, the nitrogen gas flow rate is 25 L / min - 35 L / min, the gas pressure is 0.35 MPa - 0.55 MPa, and the degassing time is 120 - 240 s. In the second stage, the nitrogen gas flow rate is 10 L / min - 20 L / min, the gas pressure is 0.2 MPa - 0.30 MPa, and the degassing time is 180 - 300 s. The degassing process of the upper rotor is carried out in two stages. In the first stage, the argon gas flow rate is 30 L / min - 45 L / min, the rotor speed is 400 rpm - 550 rpm, and the degassing time is 180 - 280 s. In the second stage, the argon gas flow rate is 50 L / min - 65 L / min, the rotor speed is 300 rpm - 380 rpm, and the degassing time is 200 - 360 s. After the degassing processes of the lower and upper parts are completed, the degassing process of the recycled aluminum melt is finally completed, and the scum on the surface of the aluminum melt in the ladle is removed.

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