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CN-122012977-A - Method for avoiding oxide skin impurity inclusion of regenerated aluminum alloy cast ingot

CN122012977ACN 122012977 ACN122012977 ACN 122012977ACN-122012977-A

Abstract

The invention discloses a method for avoiding oxide skin impurity of a regenerated aluminum alloy ingot, which relates to the field of regenerated aluminum alloy processing and comprises the steps of firstly crushing a regenerated aluminum raw material by a jaw crusher, secondly smelting in atmosphere, putting the pretreated raw material into a graphite crucible smelting furnace for smelting, thirdly purifying in two stages, namely purifying by a rotary blowing device after the melt is completely melted, and precisely casting in the fourth stage, transferring the purified melt to a vertical semicontinuous casting machine, and realizing the full-flow control of oxide skin inhibition from sources and process removal to terminal interception by a full-flow synergistic process of raw material grading pretreatment-inert gas atmosphere smelting-two-stage melt purification-precise casting control, thereby effectively reducing the oxide skin impurity amount of the regenerated aluminum alloy ingot, meeting the severe requirements of high-end fields such as automobile weight and electronic equipment shells on the purity of the ingot, and reducing the processing defects caused by oxide skin impurity.

Inventors

  • PENG BINGFENG
  • ZHANG SHENGEN
  • ZHANG BAILIN
  • HONG XIXI
  • LIU HU
  • LIU YUE
  • ZHOU ZHIPENG

Assignees

  • 江西保太有色金属集团有限公司
  • 南昌大学
  • 江西金到铝业有限公司

Dates

Publication Date
20260512
Application Date
20260303

Claims (10)

  1. 1. The method for avoiding the oxide skin impurity of the regenerated aluminum alloy cast ingot is characterized by comprising the following steps of: s1, raw material pretreatment, namely crushing a reclaimed aluminum raw material by a jaw crusher, controlling the particle size to be 20-40mm after crushing, removing metal impurities and nonmetallic impurities with the diameter of more than 5mm by using a screening machine, then placing the crushed raw material in a hot air baking furnace, baking for 1.5-2.5h at 380-420 ℃ in an atmosphere with the oxygen content of not more than 3%, and turning every 40min in the baking process; S2, smelting in atmosphere, namely putting the pretreated raw materials into a graphite crucible smelting furnace, vacuumizing until the pressure is not more than 40Pa, introducing argon, maintaining the pressure in the smelting furnace to be 0.08-0.12MPa, then heating to 800-840 ℃ for smelting to form a melt, controlling the flow of the argon to be 10-15L/min in the smelting process, and carrying out slag skimming once every 25min, wherein the slag skimming temperature is controlled to be 810-830 ℃; S3, purifying the melt by adopting a rotary blowing device after the melt is completely melted, wherein the depth of the blowing head inserted into the melt is 250-350mm, the pressure of the introduced nitrogen is 0.4-0.6MPa, the rotating speed of the device is controlled to be 180-220r/min, the purifying time is 18-22min, then the melt is filtered by a ceramic filter plate, the aperture of the filter plate is 20-40 mu m, the filtering area is 0.6-0.9m < 2 >, and the flow rate of the melt is controlled to be 0.3-0.5m/S; S4, precisely casting, namely transferring the purified melt to a vertical semicontinuous casting machine, treating the melt by an online degassing device before casting, controlling the vacuum degree of the degassing device to be 25-35Pa, the degassing time to be 6-9min, casting after treating by the degassing device, controlling the casting temperature to be 700-730 ℃, and the casting speed to be 0.6-1.0m/min, wherein the cooling water temperature of a crystallizer of the vertical semicontinuous casting machine is controlled to be 28-32 ℃, the flow rate of cooling water is controlled to be 1.8-2.2m/S, and demoulding after the cast ingot is cooled to be below 300 ℃.
  2. 2. The method for avoiding oxide skin impurity of the regenerated aluminum alloy ingot according to claim 1, wherein the crushing gap of the jaw crusher is adjusted to 15-25mm in the raw material pretreatment step, and compressed air of 0.25-0.35MPa is introduced for dedusting during crushing.
  3. 3. The method for avoiding oxide skin impurity inclusion of a regenerated aluminum alloy ingot according to claim 1, wherein the wall thickness of a graphite crucible in the atmosphere smelting step is 20-30mm, and the temperature rising rate of a smelting furnace is controlled to be 15-20 ℃ per minute.
  4. 4. The method for avoiding oxide skin impurity inclusion of a regenerated aluminum alloy ingot according to claim 1, wherein a blowing head of a rotary blowing device in the two-stage purification step is of a porous structure, the aperture is 1.5-2.5mm, and the blowing head is made of high-temperature resistant alloy.
  5. 5. The method for avoiding oxide skin impurity of the regenerated aluminum alloy ingot casting, which is characterized in that the ceramic filter plate in the two-stage purification step is of a composite structure and consists of an upper layer, a middle layer and a lower layer, wherein the pore diameter of the upper layer is 40 mu m, the pore diameter of the middle layer is 30 mu m, the pore diameter of the lower layer is 20 mu m, and the filter plate is preheated for 30-40min at 400-450 ℃ before being used.
  6. 6. The method for avoiding oxide skin impurity inclusion of a regenerated aluminum alloy ingot according to claim 5, wherein the online degassing device in the precise casting step adopts a rotor degassing machine, the rotating speed of the rotor is 400-500r/min, and the temperature fluctuation of a melt in the degassing process is controlled within plus or minus 5 ℃.
  7. 7. The method for avoiding oxide skin impurity inclusion of the regenerated aluminum alloy ingot according to claim 1, wherein a diversion trench is arranged at a casting nozzle of a casting machine in the precise casting step, and a boron nitride coating is coated on the inner wall of the diversion trench, and the thickness of the coating is 5-8 μm.
  8. 8. The method for avoiding oxide skin impurity inclusion of the regenerated aluminum alloy ingot according to claim 1, wherein a PLC control system is adopted in the raw material pretreatment step, the atmosphere smelting step, the two-stage purification step and the precise casting step, process parameters such as temperature, pressure, flow, rotating speed and the like are monitored in real time, and when the parameter deviation exceeds plus or minus 3%, the method automatically alarms and is adjusted.
  9. 9. The method for avoiding oxide skin inclusion of a secondary aluminum alloy ingot according to claim 1, wherein the aluminum content of the secondary aluminum raw material in the raw material pretreatment step is not less than 95%, the metal impurities include iron and copper, and the nonmetal impurities include plastics and rubber.
  10. 10. The method for avoiding oxide skin impurity inclusion of a regenerated aluminum alloy ingot according to claim 1, wherein the purity of the introduced argon gas in the atmosphere smelting step is not less than 99.995%, and the purity of the introduced nitrogen gas in the two-stage purifying step is not less than 99.99%.

Description

Method for avoiding oxide skin impurity inclusion of regenerated aluminum alloy cast ingot Technical Field The invention relates to the field of processing of reclaimed aluminum alloy, in particular to a method for avoiding oxide skin impurity of a reclaimed aluminum alloy cast ingot. Background Under the strategic push of global 'double carbon' targets and resource recycling, the regenerated aluminum alloy industry has become one of the core directions of aluminum industry development. The regenerated aluminum alloy takes waste aluminum products (such as waste automobile aluminum products, waste building profiles, retired aviation components and the like) as raw materials, can save more than 95% of energy consumption and reduce more than 90% of carbon emission compared with the original aluminum alloy, and is a typical green low-carbon material. However, the problem of oxide skin impurity inclusion in production is always limited, namely, the surface of a reclaimed aluminum raw material is easy to form a plurality of layers of oxide skins and has large component difference, the existing pretreatment can only remove massive impurities or pollute the environment due to element loss caused by acid washing, the smelting is in an open mode and the gas distribution is uneven, the purification technology is difficult to consider efficiency and effect, the casting parameter control precision is insufficient, so that the oxide skin impurity inclusion of the cast ingot is high, the qualification rate is low, and the requirements of the high-end field cannot be met. Therefore, it is necessary to provide a method for avoiding the oxide skin inclusion of the recycled aluminum alloy ingot to solve the above problems. Disclosure of Invention The invention aims to provide a method for avoiding oxide skin impurity inclusion of a regenerated aluminum alloy cast ingot, which aims to solve the problems that multiple layers of oxide skins are easy to form on the surface of a regenerated aluminum raw material, the component difference is large, the existing pretreatment can only remove massive impurities or element loss caused by acid washing, the environment is polluted, the smelting is in an open mode and the gas distribution is uneven, the efficiency and the effect are difficult to be considered in the purification technology, the casting parameter control precision is insufficient, the oxide skin impurity inclusion of the cast ingot is high, the qualification rate is low, and the requirement of the high-end field cannot be met. In order to achieve the aim, the invention provides the following technical scheme that the method for avoiding the impurity inclusion of the oxidized skin of the regenerated aluminum alloy cast ingot comprises the following steps: Firstly, raw material pretreatment, namely crushing a reclaimed aluminum raw material by a jaw crusher, controlling the particle size to be 20-40mm after crushing, removing metal impurities and nonmetallic impurities with the diameter of more than 5mm by using a screening machine, then placing the crushed raw material in a hot air baking furnace, baking for 1.5-2.5h at 380-420 ℃ in an atmosphere with the oxygen content of not more than 3%, and turning once every 40min in the baking process; Secondly, smelting in atmosphere, namely pouring the pretreated raw materials into a graphite crucible smelting furnace, vacuumizing until the pressure is not more than 40Pa, introducing argon, maintaining the pressure in the smelting furnace to be 0.08-0.12MPa, then heating to 800-840 ℃ for smelting to form a melt, controlling the flow of the argon to be 10-15L/min in the smelting process, and slagging off once every 25min, wherein the slagging off temperature is controlled to be 810-830 ℃; Third, two-stage purification, namely, after the melt is completely melted, a rotary blowing device is adopted to purify the melt, the depth of the inserted melt of a blowing head is 250-350mm, the pressure of the introduced nitrogen is 0.4-0.6MPa, the rotating speed of the device is controlled to be 180-220r/min, the purification time is 18-22min, then the melt is filtered by a ceramic filter plate, the aperture of the filter plate is 20-40 mu m, the filtering area is 0.6-0.9m < 2 >, and the flow rate of the melt is controlled to be 0.3-0.5m/s; Transferring the purified melt to a vertical semicontinuous casting machine, treating the melt by an online degassing device before casting, controlling the vacuum degree of the degassing device to be 25-35Pa, the degassing time to be 6-9min, casting after the treatment of the degassing device, controlling the casting temperature to be 700-730 ℃, and the casting speed to be 0.6-1.0m/min, wherein the cooling water temperature of a crystallizer of the vertical semicontinuous casting machine is controlled to be 28-32 ℃, the flow rate of cooling water is controlled to be 1.8-2.2m/s, and demoulding after the cast ingot is cooled to be below 300 ℃. Preferably, in