Iron removal method for secondary aluminum

Abstract

The invention discloses a secondary aluminum iron removal method, and belongs to the technical field of secondary aluminum iron removal, and the method comprises the following steps: adding a refining agent, an Al-3B alloy and an Al-10Sn alloy to act on a secondary aluminum alloy melt, removing impurity elements Fe, B and Sn to promote a Fe-rich phase to settle, so that the Fe-rich phase in secondary aluminum is mainly gathered at the bottom, and then cutting off the bottom. According to the method, the refining agent, the Al-3B alloy and the Al-10Sn alloy are added into the regenerated aluminum melt, so that a Fe-rich phase can be settled to the bottom of the melt, the iron removal effect is achieved, and the highest iron removal rate can reach 44.51%.

Description

Technical Field

[0001] This invention relates to the field of iron removal technology in recycled aluminum, and more particularly to a method for iron removal in recycled aluminum. Background Technology

[0002] Recycled aluminum is aluminum and aluminum alloys produced by smelting scrap aluminum as the main raw material. Its energy consumption is only 5% of that of electrolytic aluminum, and its carbon emissions are only 2.1% of those of electrolytic aluminum. Statistics show that producing 1 ton of recycled aluminum can save 3.4 tons of standard coal and 22 cubic meters of aluminum. 3 Water consumption will reduce solid waste emissions by 20 tons. Developing the recycled aluminum industry is an important way to solve my country's bauxite resource shortage and achieve carbon emission reduction and sustainable development in my country's aluminum industry.

[0003] Iron is the most harmful impurity metal element in recycled aluminum alloys. The sources of iron in recycled aluminum are complex, and are as follows: (1) Various iron nails, iron blocks, iron wires, etc. are embedded and mixed in with the scrap aluminum. These iron inclusions were not sorted and separated before the scrap aluminum was put into the furnace. They will be melted into the recycled aluminum melt during the scrap aluminum melting process. (2) During the smelting process, iron tools such as stirring rods and slag rakes that come into contact with the melt melt, increasing the iron content of the recycled aluminum melt; (3) The intermediate alloys and solvents added during the smelting process contain a certain amount of iron, which will also introduce iron into the recycled aluminum melt, increasing the iron content.

[0004] Iron has a high solubility in recycled aluminum melt, but a low solubility in the solid state. Therefore, after the recycled aluminum melt solidifies, most of the iron combines with Al, Si, Mn, etc., to form iron-containing intermetallic compounds, i.e., iron-rich phases. Iron-rich phases are divided into α-Fe and β-Fe phases. α-Fe phases are usually blocky, fishbone-like, or Chinese character-shaped, and have little impact on the properties of recycled aluminum alloys. β-Fe phases are needle-like and lamellar. Excess iron usually exists as β-Fe phase, which can fracture the aluminum matrix, causing stress concentration and becoming the crack initiation and crack propagation direction for fracture in recycled aluminum alloys, reducing their strength, plasticity, and fatigue resistance. In addition, coarse needle-like and lamellar iron-rich phases can also reduce the fluidity, filling, and feeding capacity of recycled aluminum melt, leading to shrinkage cavities and porosity in castings.

[0005] The purification of iron impurities in recycled aluminum melt can be divided into physical separation methods and flux refining methods. Physical separation methods include centrifugal sedimentation, electromagnetic purification, and ceramic filtration. However, physical separation methods are difficult to implement and costly in actual production, making them unsuitable for industrial-scale production. In contrast, flux refining methods have a simple experimental process, low cost, and are easy to promote and use in actual production.

[0006] Currently, iron removal using flux refining methods involves two approaches: one employing refining modification of the iron-rich phase, and the other using iron-removing agents. The refining modification of the iron-rich phase essentially inhibits the formation of the β-AlFeSi phase, reducing the harmful effects of iron impurities on the aluminum alloy. However, since iron still remains within the aluminum alloy, it cannot completely eliminate the harmful effects of Fe. To fundamentally remove iron and eliminate its harmful effects, the flux method is generally used. This involves adding flux to the molten aluminum, where it reacts with Fe in the recycled aluminum, capturing it and forming slag or producing precipitation, thus achieving iron removal. The flux method is time-efficient, easy to operate, does not damage castings, and is relatively inexpensive, allowing for mass production. Currently, flux methods all involve adding boron-based compounds to introduce boron (B), which then reacts with iron to form Fe2B. This Fe2B then settles at the bottom of the melt, forming slag and thus reducing the Fe content. The literature "Khaliq A. Thermodynamics and kinetics of transition metalborides formation in molten aluminum [D]. Melbourne: Swinburne University of Technology, 2013" indicates that boron-containing compounds function similarly to rare earth elements, exhibiting a high iron removal rate and effectively controlling the morphology of the iron-rich phase. By limiting the solid solubility of iron in aluminum alloys, reducing iron precipitation, and promoting greater Fe distribution at grain boundaries, the grains are refined, and thermal stability is improved. The combination of boron and aluminum forms AlB2 and AlB2. 12Compounds can capture transition metal elements in aluminum, forming their corresponding borides which then precipitate. For example, the literature "Wang Yanbing, Yi Guangbin, Yang Xiangjie. Effect of Na2B4O7 on Iron Removal in Recycled Aluminum Alloys [J]. Foundry, 2014, 63(10):1024-1027" shows that the amount of Na2B4O7 added, the reaction temperature, and the holding time all affect the iron removal effect of recycled aluminum alloys, with the amount added having the most significant impact. Experiments revealed that the optimal amount of Na2B4O7 added was 0.5%, at which point the iron removal rate reached 7.57%. For example, the literature "Gao Jianwei, Purification Effect and Mechanism of Borides on Iron Impurities in Melt Aluminum [D]. Shanghai Jiaotong University, 2010" describes the removal of iron from industrial pure aluminum by adding sodium chloride, potassium chloride, and borax. The iron content was reduced from the initial 0.14 wt.%, 0.66 wt.%, and 1.08 wt.% to 0.08 wt.%, 0.45 wt.%, and 0.84 wt.%, with iron removal rates reaching 42.9%, 31.8%, and 22.2%, respectively. However, this technique, representing the use of boron (B) for iron removal, suffers from the same technical problem: while the iron removal rate is generally satisfactory under low iron content conditions, it significantly decreases when removing iron from aluminum alloys with high iron content. The literature “Yang Huaide, Study on the Mechanism of Iron Removal from Regenerated Al-Si Alloy by Borides and Manganese [J], Rare Metals Materials and Engineering, 2015, 44(3): 621-627” studied the effects of KBF4 and KBF4, Mn on the iron-rich phase transformation behavior in regenerated Al-Si alloys and explored the iron removal method using sedimentation. The study showed that the iron content of aluminum ingots formed by the furnace cooling of regenerated Al-Si melt with added borides (KBF4) and Mn increased with the distance from the top of the aluminum ingot. The iron content in the upper part of the aluminum ingot was lower than the original amount. That is, the iron content in the upper part of the regenerated Al-Si melt with added borides and Mn was 0.5744%, while the original iron content of the regenerated Al-Si melt was 0.8427%, that is, the iron removal effect reached 31.83%. However, KBF4 will produce toxic gas when heated at high temperature, which is not conducive to the promotion and use in actual production. The literature “Tan Xiping, Zheng Kaihong, Zhang Xinming, et al. Effect of boron oxide on impurity iron in recycled A356 aluminum alloy [J]. Materials Reports, 2013, 27(22): 92-95” found that by changing the amount of B2O3 added to the aluminum melt and the holding time, the purification effect of Fe was the best, reaching 26.5%, when the amount of B2O3 added was 0.6% of the aluminum melt and the holding time was 90 min.

[0007] Therefore, using only a flux method containing boron (B) cannot achieve a high iron removal rate, and its application in recycled aluminum alloys with an iron content of less than 1% is limited. Currently, there are no reports on the use of other elements in flux methods. Based on the fundamental principles of the flux method, a new iron removal agent needs to meet the following technical characteristics: stable iron removal effect; iron compounds should settle to the bottom of the melt and not decompose; it should be applicable to recycled aluminum alloys with a wide iron content range (0.5%-1.5%) while still achieving a high iron removal rate; and furthermore, it should solve the problem of complex preparation of the iron removal agent, eliminating the need for dehydration, ball milling, and other processes. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a method for removing iron from recycled aluminum. When the iron content in the recycled aluminum alloy is 0.6-1.5 wt.%, it has a high iron removal rate for the recycled aluminum alloy. The method is simple to operate, the iron removal flux has low viscosity, and there is no pollution.

[0009] To address the aforementioned technical problems, the present invention adopts the following solution: A method for removing iron from recycled aluminum involves adding a refining agent, Al-3B alloy, and Al-10Sn alloy to the recycled aluminum alloy melt to remove impurity elements Fe, B, and Sn. These elements react with iron to form a corresponding iron-rich phase, and the density of this iron-rich phase is greater than that of the molten aluminum. This causes the Fe-rich phase to settle, resulting in the Fe-rich phase accumulating at the bottom of the recycled aluminum, which is then removed.

[0010] The content of the recycled aluminum iron is 0.6%-1.5 wt.%.

[0011] Furthermore, the amount of the refining agent added is 0.3-0.7 wt.%.

[0012] Furthermore, the Al-3B alloy is added in an amount of 0.4-0.8 wt.%.

[0013] Furthermore, the Al-10Sn alloy is added in an amount of 5 wt.%-20 wt.%.

[0014] Furthermore, the amount of the refining agent added is 0.6 wt.%; the amount of the Al-3B alloy added is 0.6 wt.%; and the amount of the Al-10Sn alloy added is 10 wt.%.

[0015] The method for removing iron from recycled aluminum includes the following steps: Step 1: Preparation of raw materials: Weigh the refining agent, Al-3B alloy, and Al-10Sn according to the weight ratio with recycled aluminum. Then wrap the refining agent, Al-3B alloy, and Al-10Sn in aluminum foil and preheat them at the set temperature to obtain the iron removal agent. At the same time, heat and melt the recycled aluminum to obtain the recycled aluminum alloy melt. Step 2, Iron removal from recycled aluminum alloy: Before smelting, heat and melt the Al-3B alloy along with the recycled aluminum alloy melt. When the melt temperature reaches the set temperature, add the preheated refining agent to the recycled aluminum alloy melt, stir 2-3 times, and remove the slag. After holding at the temperature for 10 minutes, add the Al-10Sn alloy. After reacting for 10 minutes, perform the iron removal operation for the set time. After the iron removal operation is completed, cool it to room temperature in the air to obtain the recycled aluminum alloy after iron removal. Finally, cut it off from the bottom of the recycled aluminum alloy to complete the iron removal of the recycled aluminum alloy.

[0016] Furthermore, the preheating temperature in step 1 is 100℃-200℃.

[0017] Furthermore, the conditions for the iron removal operation in step 2 are as follows: the iron removal temperature is 700-800℃ and the iron removal time is 30-90min.

[0018] To achieve the purpose of this invention, the basic principle is as follows: by introducing a new element, it can react with Fe in the temperature range of 700-800℃ to form an iron-containing compound. Furthermore, the density of this iron-containing compound is greater than that of molten aluminum, causing it to settle and accumulate at the bottom of the melt. This increases the iron content at the bottom of the melt and decreases the iron content at the top. By cutting away the iron-rich bottom, the iron removal effect of the recycled aluminum alloy can be achieved. In addition, the introduced element should only react with iron, not harm the matrix, and the additive should be non-polluting.

[0019] This invention uses direct-reading spectroscopy to demonstrate that adding refining agent + Al-3B alloy + Al-10Sn alloy to recycled aluminum alloy melt can cause the Fe-rich phase to settle to the bottom of the melt, resulting in an iron removal effect with an iron removal rate of 25.0-45.0%.

[0020] Compared with existing technologies, this invention introduces B and Sn elements in stages, which react with Fe to form iron-containing compounds within a temperature range of 700-800℃. The Fe-rich phase of these iron-containing compounds has a higher density than the molten aluminum, causing it to settle and accumulate at the bottom of the melt, increasing the iron content at the bottom and decreasing the iron content at the top. Finally, the iron-rich bottom layer of the recycled aluminum alloy is removed, achieving iron removal from the recycled aluminum alloy. This invention uses direct-reading spectroscopy to detect the Fe content in the recycled aluminum alloy. The addition of refining agent + Al-3B alloy + Al-10Sn alloy causes the Fe-rich phase to settle to the bottom of the melt, resulting in iron removal. The iron removal rate can reach up to 44.51%, and the iron removal operation is simple. Furthermore, in addition to removing iron, the introduced elements can also remove other impurities from the recycled aluminum, better purifying the recycled aluminum matrix without harming it; the additives are non-polluting. Attached Figure Description

[0021] Figure 1 Image of a sample prepared before the reclaimed aluminum alloy is removed; Figure 2 The curves showing the effect of Al-10Sn dosage on iron removal rate when the refining agent is 0.6 wt.% and the Al-3B alloy is 0.6 wt.%; Figure 3 The curves showing the effect of Al-3B alloy on iron removal rate when the refining agent is 0.6 wt.% and the Al-10Sn content is 10 wt.%; Figure 4 The curves showing the effect of refining agent on iron removal rate when Al-3B alloy content is 0.6 wt.% and Al-10Sn content is 10 wt.%; Figure 5 The curve showing the effect of settling time on iron removal rate at 780℃ is shown. Figure 6 The curve showing the effect of settling time on iron removal rate at 780℃ without the addition of Al10Sn; Figure 7 The curve shows the effect of adding only Al-10Sn on the iron removal effect of recycled aluminum. Detailed Implementation

[0022] The inventive concept of this invention is as follows: Addressing the problems of low iron removal rate, complex operation, high viscosity of the iron removal flux, and pollution associated with existing technologies for removing iron from recycled aluminum alloy melts, the inventors discovered that adding a refining agent, Al-3B alloy, and Al-10Sn alloy within the temperature range of 700-800℃ can remove Fe from recycled aluminum. The addition of the refining agent and Al-3B alloy forms slag. After stirring and skimming the slag, Al-10Sn alloy is added to introduce Sn. The B and Sn elements react with Fe in the recycled aluminum alloy melt to generate iron-rich phase compounds, which sink to the bottom. Removing the bottom of the compound completes the iron removal process.

[0023] The specific implementation method is as follows: Example 1: A method for removing iron from recycled aluminum, wherein the amount of refining agent in the recycled aluminum melt is 0.6 wt.%, the amount of Al-3B alloy is 0.6 wt.%, and 10 wt.% Al-10Sn is added. The specific steps are as follows: Step 1: Raw material preparation: Using refining agent + Al-3B alloy + Al-10Sn alloy as the iron removal agent, weigh 400g of recycled aluminum alloy, weigh 0.6wt.% of refining agent and 0.6wt.% of Al-3B alloy according to the weight ratio with recycled aluminum, weigh 10wt.% of Al-10Sn alloy, then wrap the refining agent, Al-3B alloy and Al-10Sn alloy in aluminum foil and preheat at 100℃-200℃ to obtain the preheated iron removal agent. At the same time, heat and melt the recycled aluminum to obtain the recycled aluminum alloy melt. Step 2: Iron removal from recycled aluminum alloy: Before smelting, heat and melt the Al-3B alloy along with the recycled aluminum alloy melt. When the melt temperature reaches 700℃-800℃, add the preheated refining agent to the recycled aluminum alloy melt, react for 10 minutes, stir 2-3 times, and remove slag. After holding at the temperature for 10 minutes, add the Al-10Sn alloy to perform iron removal for 30-90 minutes. After the iron removal is completed, cool it to room temperature in air to obtain the recycled aluminum alloy after iron removal. Finally, cut it off from the bottom of the recycled aluminum alloy to complete the iron removal process.

[0024] Example 2: A method for removing iron from recycled aluminum, wherein the amount of refining agent in the recycled aluminum melt is 0.6 wt.%, the amount of Al-3B alloy is 0.6 wt.%, and 5 wt.% Al-10Sn is added. The specific steps are as follows: Step 1, Raw material preparation: Using refining agent + Al-3B alloy + Al-10Sn alloy as iron removal agent, weigh 400g of recycled aluminum alloy, weigh 0.6wt.%t of refining agent and 0.6wt.% of Al-3B alloy according to the weight ratio with recycled aluminum, weigh 5wt.% of Al-10Sn alloy, then wrap the refining agent, Al-3B alloy and Al-10Sn alloy in aluminum foil, and preheat at 100℃-200℃ to obtain the preheated iron removal agent. At the same time, heat and melt the recycled aluminum to obtain the recycled aluminum alloy melt. Step 2: Iron removal from recycled aluminum alloy: Before smelting, heat and melt the Al-3B alloy along with the recycled aluminum alloy melt. When the melt temperature reaches 700℃-800℃, add the preheated refining agent to the recycled aluminum alloy melt, react for 10 minutes, stir 2-3 times, and remove slag. After holding at the temperature for 10 minutes, add the Al-10Sn alloy to perform iron removal for 30-90 minutes. After the iron removal is completed, cool it to room temperature in air to obtain the recycled aluminum alloy after iron removal. Finally, cut it off from the bottom of the recycled aluminum alloy to complete the iron removal process.

[0025] Example 3: A method for removing iron from recycled aluminum, wherein the amount of refining agent in the recycled aluminum melt is 0.6 wt.%, the amount of Al-3B alloy is 0.6 wt.%, and 15 wt.% Al-10Sn is added. The specific steps are as follows: Step 1: Raw material preparation: Using refining agent + Al-3B alloy + Al-10Sn alloy as the iron removal agent, weigh 400g of recycled aluminum alloy, weigh 0.6wt.% of refining agent and 0.6wt.% of Al-3B alloy according to the weight ratio with recycled aluminum, weigh 15wt.% of Al-10Sn alloy, then wrap the refining agent, Al-3B alloy and Al-10Sn alloy in aluminum foil and preheat at 100℃-200℃ to obtain the preheated iron removal agent. At the same time, heat and melt the recycled aluminum to obtain the recycled aluminum alloy melt. Step 2: Iron removal from recycled aluminum alloy: Before smelting, heat and melt the Al-3B alloy along with the recycled aluminum alloy melt. When the melt temperature reaches 700℃-800℃, add the preheated refining agent to the recycled aluminum alloy melt, react for 10 minutes, stir 2-3 times, and remove slag. After holding at the temperature for 10 minutes, add the Al-10Sn alloy to perform iron removal for 30-90 minutes. After the iron removal is completed, cool it to room temperature in air to obtain the recycled aluminum alloy after iron removal. Finally, cut it off from the bottom of the recycled aluminum alloy to complete the iron removal process.

[0026] Example 4: A method for removing iron from recycled aluminum, wherein the amount of refining agent in the recycled aluminum melt is 0.6 wt.%, the amount of Al-3B alloy is 0.6 wt.%, and 20 wt.% Al-10Sn is added. The specific steps are as follows: Step 1: Raw material preparation: Using refining agent + Al-3B alloy + Al-10Sn alloy as the iron removal agent, weigh 400g of recycled aluminum alloy, weigh 0.6wt.% of refining agent and 0.6wt.% of Al-3B alloy according to the weight ratio with recycled aluminum, weigh 20wt.% of Al-10Sn alloy, then wrap the refining agent, Al-3B alloy and Al-10Sn alloy in aluminum foil and preheat at 100℃-200℃ to obtain the preheated iron removal agent. At the same time, heat and melt the recycled aluminum to obtain the recycled aluminum alloy melt. Step 2: Iron removal from recycled aluminum alloy: Before smelting, heat and melt the Al-3B alloy along with the recycled aluminum alloy melt. When the melt temperature reaches 700℃-800℃, add the preheated refining agent to the recycled aluminum alloy melt, react for 10 minutes, stir 2-3 times, and remove slag. After holding at the temperature for 10 minutes, add the Al-10Sn alloy to perform iron removal for 30-90 minutes. After the iron removal is completed, cool it to room temperature in air to obtain the recycled aluminum alloy after iron removal. Finally, cut it off from the bottom of the recycled aluminum alloy to complete the iron removal process.

[0027] Comparative Example 1: A method for removing iron from recycled aluminum, wherein 0.6 wt.% of a refining agent, 0.6 wt.% of Al-3B alloy, and 1 wt.% of Al-10Sn are added to the recycled aluminum melt. The specific steps are as follows: Step 1, Raw material preparation: Using refining agent + Al-3B alloy + Al-10Sn alloy as iron removal agent, weigh 400g of recycled aluminum alloy, weigh 0.6wt.% refining agent and 0.6wt.% Al-3B alloy according to the weight ratio with recycled aluminum, weigh 1wt.% Al-10Sn, then wrap the refining agent, Al-3B alloy and Al-10Sn alloy in aluminum foil, and preheat at 100℃-200℃ to obtain the preheated iron removal agent. At the same time, heat and melt the recycled aluminum to obtain the recycled aluminum alloy melt. Step 2: Iron removal from recycled aluminum alloy: Before smelting, heat and melt the Al-3B alloy along with the recycled aluminum alloy melt. When the melt temperature reaches 700℃-800℃, add the preheated refining agent to the recycled aluminum alloy melt, react for 10 minutes, stir 2-3 times, and remove slag. After holding at the temperature for 10 minutes, add the Al-10Sn alloy to perform iron removal for 30-90 minutes. After the iron removal is completed, cool it to room temperature in air to obtain the recycled aluminum alloy after iron removal. Finally, cut it off from the bottom of the recycled aluminum alloy to complete the iron removal process.

[0028] Because tin has a low melting point, adding it first will result in significant burn-off. Therefore, tin must be added before tin.

[0029] To demonstrate the iron removal effect of the iron removal method of the present invention, iron removal samples were taken at a depth of 5 cm from the alloys prepared in Examples 1-4 and Comparative Example 1, respectively. Figure 1 As shown, direct-reading spectral testing was performed, and the iron removal rate was converted as follows: Figure 2 As shown in the figure. Experimental results show that the iron content at 5 cm depth in the recycled aluminum alloy decreases, and the iron removal rate at 5 cm depth reaches a maximum of 44.51%. The addition of refining agent + Al-3B alloy + Al-10Sn alloy achieves the effect of Fe-rich phase settling to the bottom of the alloy, thus obtaining the iron removal effect.

[0030] Comparative Example 2: A method for processing recycled aluminum alloy without adding Al-10Sn alloy. Unless otherwise specified, the steps are the same as in Example 1, with the refining agent being 0.6 wt.% and the Al-3B alloy being 0.6 wt.%. The difference is that step 2 does not involve adding Al-10Sn alloy or related steps, thus obtaining recycled aluminum alloy without adding Al-10Sn alloy.

[0031] To demonstrate the effect of adding Al-10Sn alloy on iron removal, direct-reading spectra were performed at 5 cm on the recycled aluminum alloy of Comparative Example 2, and the iron removal rate was converted to 4.45%. The experimental results show that the iron content in the recycled aluminum alloy did not change significantly.

[0032] To further demonstrate the effect of Al-3B alloy addition on iron removal efficiency, Examples 5-8 are provided, namely, methods for removing iron from recycled aluminum alloys when the Al-10Sn alloy addition is 10 wt.%, the refining agent dosage is 0.6 wt.%, and the Al-3B alloy dosage is 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, and 0.8 wt.%.

[0033] Examples 5-8: A method for removing Fe impurities from recycled aluminum using a refining agent, Al-10Sn alloy, and Al-3B alloy. The refining agent is 0.6 wt.%, and the Al-10Sn alloy is 10 wt.%. Unless otherwise specified, the steps are the same as in Example 1. The difference is that in step 1 of Examples 5-8, the Al-3B alloy is added in amounts of 0.4 wt.%, 0.5 wt.%, 0.7 wt.%, and 0.8 wt.%, respectively.

[0034] To demonstrate the iron removal effect of the iron removal method of this invention, direct-reading spectra were performed at 5 cm depth on the recycled aluminum alloys after iron removal in Examples 5-8, and the results were converted into iron removal rates. Combined with the data from Example 1, the experimental results are as follows: Figure 3 As shown.

[0035] To demonstrate the effect of refining agent addition on iron removal efficiency, Examples 9-13 are provided, namely, methods for removing iron from recycled aluminum alloys when the Al-10Sn alloy addition amount is 10 wt.%, the Al-3B alloy addition amount is 0.6 wt.%, and the refining agent addition amounts are 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.7 wt.%, and 0.8 wt.%.

[0036] Examples 9-13: A method for removing Fe impurities from recycled aluminum using a combination of a refining agent, Al-10Sn alloy, and Al-3B alloy is described. The Al-3B alloy is used at a dosage of 0.6 wt.%, and the Al-10Sn alloy is used at a dosage of 10 wt.%. Unless otherwise specified, the steps are the same as in Example 1, except that the refining agent dosages in step 1 of Examples 9-13 are 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.7 wt.%, and 0.8 wt.%, respectively.

[0037] To demonstrate the effectiveness of the refining agent in removing iron from recycled aluminum, direct-reading spectra were performed at 5 cm depth on the recycled aluminum alloys after iron removal in Examples 9-13, and the results were converted into iron removal rates. Combined with data from Example 1, the experimental results are as follows: Figure 4 As shown.

[0038] To illustrate the effect of iron removal operation time on iron removal efficiency, Examples 14-16 are provided, where the Al-10Sn alloy addition amount is 10 wt.%, the Al-3B alloy addition amount is 0.6 wt.%, the refining agent addition amount is 0.6 wt.%, and the iron removal operation time is 30 min, 60 min, and 90 min respectively in Examples 14-16.

[0039] Examples 14-16: A method for removing Fe impurities from recycled aluminum using a combination of refining agent, Al-10Sn alloy, and Al-3B alloy is described. The Al-3B alloy dosage is 0.6 wt.%, the refining agent dosage is 0.6 wt.%, and the Al-10Sn dosage is 10 wt.%. Unless otherwise specified, the steps are the same as in Example 1, except that in Step 2 of Examples 14-16, the iron removal operation time in the furnace at 780°C is 30 min, 60 min, and 90 min, respectively.

[0040] Comparative Example 3 differs from Examples 14-16 in that the iron removal operation time is 120 min.

[0041] To demonstrate the iron removal effect of the iron removal method of this invention, direct-reading spectra were performed at 5 cm depth on the recycled aluminum alloys after iron removal in Examples 14-16 and Comparative Example 3, and the results were converted into iron removal rates. The experimental results are as follows: Figure 5 As shown.

[0042] Comparative Examples 4-7: A method for removing Fe impurities from recycled aluminum is proposed, based on the addition of a refining agent, Al-10Sn alloy, and Al-3B alloy. The Al-3B alloy dosage is 0.6 wt.%, the refining agent dosage is 0.6 wt.%, and Al-10Sn is not added. Unless otherwise specified, the steps are the same as in Example 1, except that the settling time in the furnace at 780°C in step 2 of Comparative Examples 4-7 is 30 min, 60 min, 90 min, and 120 min, respectively. To demonstrate the iron removal effect of this invention, direct-reading spectra were performed at 5 cm from the recycled aluminum alloys of Comparative Examples 4-7, and the results were converted into iron removal rates. The experimental results are as follows: Figure 6 As shown.

[0043] Comparative Examples 8-11: To verify the effect of adding only Al-10Sn alloy on the removal of Fe impurity from recycled aluminum, the iron removal process in Comparative Examples 8-11 was the same as in Example 1 unless otherwise specified. The difference was that in step 1 of Comparative Example 8, Al-3B alloy and refining agent were not added; only Al-10Sn was added, and the amounts of Al-10Sn in Comparative Examples 8-11 were 5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%, respectively. To demonstrate the iron removal effect of the present invention, direct-reading spectra of the recycled aluminum alloy in Comparative Example 8 were measured at 5 cm, and the results were converted into iron removal rates. The experimental results are as follows: Figure 7 As shown.

[0044] This invention is based on a method for removing iron using a refining agent + Al-3B alloy + Al-10Sn alloy. The refining agent + Al-3B alloy and Al-10Sn alloy are used as iron removal agents. The iron content of the recycled aluminum alloy is 0.6%-1.5%. In the above embodiments and comparative examples, the recycled aluminum used was aluminum alloy from waste aluminum such as beverage cans. The iron removal method is a flux method. The basic principle is that by introducing B and Sn elements, a Fe-rich phase is formed, which promotes the sedimentation of the Fe-rich phase, causing the Fe-rich phase in the recycled aluminum to mainly accumulate at the bottom. Then, the bottom of the recycled aluminum alloy is removed to achieve the iron removal effect. The iron removal rate can reach up to 44.51%.

[0045] The present invention has the following advantages: 1) By introducing B and Sn elements, the B and Sn phases form an iron-rich phase with iron, which sinks to the bottom of the recycled aluminum melt, promoting the precipitation of the Fe-rich phase and ultimately reducing the iron content at the top. 2) It also has a stable and efficient iron removal effect on Fe-containing Al-Si alloys; 3) The process is simple.

[0046] In summary, the iron removal method used in this invention has a good effect on iron removal from recycled aluminum.

Claims

1. A method for removing iron from secondary aluminum, characterized in that, The method is: by adding refining agent + Al-3B alloy + Al-10Sn alloy acting on the recycled aluminum alloy melt, B element and Sn element promote the settlement of Fe-rich phase, so that the Fe-rich phase in the recycled aluminum is gathered at the bottom, and then the bottom is cut off.

2. A method of removing iron from a secondary aluminium alloy according to claim 1, characterized in that: The adding amount of the refining agent is 0.3wt.%-0.7wt.%.

3. A method of removing iron from a secondary aluminium alloy according to claim 1, characterized in that: The adding amount of the Al-3B alloy is 0.4wt.%-0.8wt.%.

4. A method of removing iron from a recycled aluminium alloy according to any one of claims 1 to 3, characterised in that: The adding amount of the Al-10Sn alloy is 5wt.%-20wt.%.

5. A method of removing iron from a secondary aluminium alloy according to claim 4, characterised in that: The adding amount of the refining agent is 0.6wt.%.

6. The method for removing iron from secondary aluminum according to claim 1, wherein The method comprises the following specific steps: Step 1, preparation of raw materials: respectively according to the weight ratio of recycled aluminum, refining agent, Al-3B alloy, Al-10Sn is weighed, then the refining agent, Al-3B alloy, Al-10Sn is respectively wrapped with aluminum foil, and preheated at a set temperature, that is, the iron removal agent is obtained, at the same time, the recycled aluminum is heated and melted to obtain recycled aluminum alloy melt; Step 2, iron removal operation of recycled aluminum alloy: before melting, Al-3B alloy is added to the recycled aluminum alloy melt, when the melt temperature reaches the set temperature, the preheated refining agent is added to the recycled aluminum alloy melt, stirred for 2-3 times, and the slag is removed, after 10 minutes of insulation, Al-10Sn alloy is added, after 10 minutes of reaction, the iron removal operation is set, after the iron removal operation is completed, it is cooled to room temperature in the air, and then the recycled aluminum alloy after iron removal operation is obtained, finally, the recycled aluminum alloy is cut off from the bottom, and the iron removal of the recycled aluminum alloy is completed.

7. The method of claim 5, wherein the method further comprises: The preheating temperature in step 1 is 100-200℃.

8. The method of claim 5, wherein: The iron removal operation conditions in step 2 are: the iron removal temperature is 700-800℃, and the iron removal time is 30-90min.

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