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CN-117802344-B - Method for upgrading and recycling cast aluminum alloy

CN117802344BCN 117802344 BCN117802344 BCN 117802344BCN-117802344-B

Abstract

The invention relates to a method for upgrading and recycling a cast aluminum alloy, which comprises the following steps of (1) smelting the cast aluminum alloy to obtain a first melt, (2) sampling the first melt and analyzing element content, (3) calculating the usage amount of an Fe-rich phase precipitating agent, (4) adding the Fe-rich phase precipitating agent into the first melt and maintaining the temperature to obtain a second melt, (5) adding a refining agent into the second melt to perform combined refining to obtain a third melt, (6) calculating the initial precipitation temperature of an alpha-Al phase, (7) cooling the third melt to generate Fe-rich phase particles and maintaining the third melt for a time to obtain a fourth melt, (8) cooling the fourth melt to obtain an ingot blank, and (9) sawing the ingot blank to obtain an ingot and a Fe-rich phase deposition layer. The method improves the Fe removal efficiency of the ingot blank, has obvious Fe removal effect, and the finally obtained 4XXX forged aluminum alloy ingot blank has the advantages of large weight and high purity, and also has the production efficiency, so that the production cost is generally reduced, and the aim of upgrading and converting the aluminum alloy ingot blank into the forged aluminum alloy with higher added value is fulfilled.

Inventors

  • HAN YI
  • ZHAO PIZHI
  • YANG SHUYU
  • FENG DAN
  • CAO YIHENG
  • QIAN LIJUN
  • ZHU RANRAN
  • LI XIULEI

Assignees

  • 中铝材料应用研究院有限公司
  • 重庆国创轻合金研究院有限公司
  • 中国铝业集团高端制造股份有限公司

Dates

Publication Date
20260505
Application Date
20231229

Claims (15)

  1. 1. A method for removing Fe element from a cast aluminum alloy comprising the steps of: (1) Smelting the cast aluminum alloy at a first temperature to obtain a first melt, wherein the first temperature is 700-780 ℃; (2) Sampling and analyzing the first melt obtained in step (1) to obtain Fe element content, si element content and Cr element content of the cast aluminum alloy; (3) Calculating the amount of Fe-rich phase precipitation agent according to the Si-Cr ratio based on the Si element content and Cr element content obtained in the step (2), wherein the Fe-rich phase precipitation agent is an Al-Cr master alloy; (4) Adding the Fe-rich phase precipitating agent into the first melt obtained in the step (1), and maintaining the first temperature for a first time to obtain a second melt, wherein the first time is 10-30 min; (5) Adding a refining agent into the second melt obtained in the step (4), continuously introducing inert gas at the first temperature to perform combined refining, standing for a second time, and removing scum to obtain a third melt, wherein the second time is 10-30 min, and the mass of the refining agent is 0.2-0.5% of the mass of the second melt; (6) Calculating the starting precipitation temperature of the alpha-Al phase based on the content of each element obtained in the step (2); (7) Cooling the third melt treated in step (5) to a second temperature at a first cooling rate to produce Fe-rich phase particles and for a third time to obtain a fourth melt; (8) Cooling the fourth melt obtained in step (7) to a third temperature at a second cooling rate to obtain an ingot, wherein the third temperature is 200 ℃ or less, and (9) Sawing the ingot from the bottom of the ingot by a first length to obtain a first ingot serving as a 4XXX forged aluminum alloy ingot and a second ingot serving as an Fe-rich phase deposition layer, wherein the first length is 1-20% of the total length of the ingot, and the ingot is characterized in that: The usage amount of the Fe-rich phase separating out agent is that the mass ratio of Si to Cr in the second melt is 20-30; the first cooling rate is 0.01-1 ℃ per second; The second temperature is within + -20 ℃ of the alpha-Al phase start precipitation temperature calculated in step (6); the second cooling rate is 20 ℃ or higher, and And the third time is 10-120 min.
  2. 2. The method according to claim 1, characterized in that: The usage amount of the Fe-rich phase separating out agent is that the mass ratio of Si to Cr in the second melt is 23-28; the first cooling rate is 0.02-0.7 ℃ per second; The second temperature is within + -8 ℃ of the alpha-Al phase start precipitation temperature calculated in step (6), and And the third time is 10-60 min.
  3. 3. The method of claim 2, wherein the second melt has a Si to Cr mass ratio of 23.5, 25.2, 25.9, 27.0 or 27.6.
  4. 4. The method of claim 2, wherein the first cooling rate is 0.023 ℃ per second.
  5. 5. The method of claim 2, wherein the second temperature is 580 ℃, 576 ℃, or 575 ℃.
  6. 6. The method of claim 2, wherein the third time is 10-30 min.
  7. 7. The method of claim 2, wherein the third time is 10 minutes, 30 minutes, or 60 minutes.
  8. 8. The method according to claim 1, characterized in that: the content of Cr element in the Al-Cr intermediate alloy is 5-20wt%.
  9. 9. The method according to claim 1, characterized in that: The main components of the refining agent are MgCl 2 and KCl, wherein the mass ratio of MgCl 2 to KCl is 0.5-1.5.
  10. 10. The method according to claim 1, characterized in that: And (3) carrying out degassing refining by introducing inert gas by using a degassing machine, wherein the blowing amount is 500-2000 mL/min.
  11. 11. The method according to claim 1, characterized in that: Step (7) is performed without stirring the melt, and the residual Cr element content in the fourth melt is less than 0.1wt.%.
  12. 12. The method according to claim 1, characterized in that: step (8) is performed without stirring the melt, and the second cooling rate is 20 ℃ per second.
  13. 13. The method according to any one of claims 1-12, wherein: The initial Fe element content in the cast aluminum alloy is at least 0.5wt%, optionally the Ni element content of the cast aluminum alloy is 0-1.0 wt%, the Sn element content is 0-0.5 wt%, the Mg element content is 0-6.0 wt%, the Cu element content is 0-6.0 wt%, the Zn element content is 0-6.0 wt%, the Ti element content is 0-0.3 wt%, the rest of single impurity elements are less than or equal to 0.05 wt%, and the rest of Al.
  14. 14. The method according to claim 13, wherein the cast aluminum alloy has an Fe element content of 0.5 to 4.0wt.%, an Si element content of 6.0 to 15.0wt.%, and a Cr element content of 0 to 0.1wt.%, and the balance being Al.
  15. 15. The method according to any one of claims 1-12, wherein: Compared with the cast aluminum alloy, the content of Fe element in the first cast ingot is reduced by 40-70%, and the weight of the first cast ingot is more than 80% of the weight of the cast aluminum alloy.

Description

Method for upgrading and recycling cast aluminum alloy Technical Field The present invention relates to the field of metallurgy. In particular, the invention relates to the technical field of preparing regenerated aluminum by removing impurities from waste aluminum, in particular to a method for removing Fe element from cast aluminum alloy, and particularly relates to a method for efficiently removing Fe element from waste cast aluminum alloy. Background The regenerated aluminum industry has the advantages of low carbon, environmental protection, energy conservation and consumption reduction, is an important way for sustainable development of the aluminum processing industry in China, and has very important significance in developing the regenerated aluminum industry especially under the conditions of lack of bauxite resources in China and the strategy of greatly promoting carbon to peak carbon neutralization in China. However, compared with developed countries, china still has a relatively lag in the recycling mode of waste aluminum at present. For a long time, the method is influenced by the complex components of the waste aluminum raw materials, most regenerated aluminum alloy produced in China has higher impurity element content and can only be used for producing cast aluminum alloy products, and a lot of high-quality deformed aluminum alloy waste materials are degraded for use, so that the recovery value of the aluminum products is greatly reduced, and huge waste of waste aluminum resources is caused. According to statistics, only about 20% of regenerated aluminum in China can be regenerated into deformed aluminum alloys with corresponding brands each year, and the grade-keeping recycling is achieved. However, in the structure of recycled aluminum products in developed countries, the fraction of wrought aluminum alloys is more than half. Therefore, how to make the same grade or upgrade recycling of the regenerated aluminum is a difficult problem to overcome in the current regenerated aluminum industry. Because of complex sources of waste aluminum and high pretreatment difficulty, a large amount of impurity elements are inevitably mixed in the process of repeatedly recycling and preparing the reclaimed aluminum, and the method can effectively reduce the content of the impurity elements, thereby being an important precondition for ensuring the same level or upgrading and recycling of the reclaimed aluminum. Among the impurity elements, the hazard effect of Fe element is most remarkable, and the quality of the regenerated aluminum is seriously affected. At present, the method for reducing the harmful effect of impurity Fe element mainly comprises two modes, namely adopting modification treatment, changing the morphology of Fe-rich phase by adding chemical elements or adopting a special process, such as Mn, cr, be, co, ni or rare earth elements, and the like, and adopting a physical method to remove the Fe-rich phase by utilizing different physical and chemical properties between the Fe-rich phase and melt, including methods of gravity separation, centrifugal separation, gravity sedimentation, flux refining, and the like. The methods have different effects of separating the Fe-rich phases and different qualities of the purified aluminum actually recovered. However, these separation methods remain in the laboratory research stage and have not yet been applied on an industrial scale. Among these separation methods, gravity sedimentation is a method of using the density difference between the Fe-rich phase and the aluminum alloy melt to deposit the Fe-rich phase at the bottom of the melt, thereby reducing the Fe element content in the melt. Relatively, the method is simple and feasible and is easy to popularize and apply industrially. However, the existing difficulty is that whether a proper additive element can be found or not, and the additive element and Fe element can form primary Fe-rich phase particles which are easy to settle and separate in a melt, so that the content of Fe element impurities in the aluminum scrap alloy is reduced, and meanwhile, new impurity elements are not introduced, so that the purified aluminum scrap alloy meets the alloy component range with higher added value, and the same grade or upgrading recycling of the aluminum scrap is realized. The prior patent CN107619959B reduces the content of Fe element in the reclaimed aluminum by jointly adding Al-Cr intermediate and K 2TiF6 with the mass ratio of (1.26-1.78) and adopting a ceramic foam filter screen to filter out the precipitate at the bottom of the aluminum liquid. Therefore, ti element is additionally introduced, and Fe filtering measures are needed to be added, so that the viscosity becomes large after the temperature of the melt is reduced, and the industrial implementation is difficult. Prior patent CN111032890a discloses the initial Fe content (greater than 0.20 wt.%) and Mn content (no greater than 1.8 wt.%) of the alloy,