Method for recycling of waste aluminum without downgrading

Abstract

A method for recycling of waste aluminum without downgrading, comprising: crushing a waste aluminum alloy material to a preset particle size to obtain a crude aluminum alloy material; carrying out magnetic separation and impurity removal on the crude aluminum alloy material to respectively obtain an iron product material and a first aluminum alloy material; carrying out electric separation and impurity removal on the first aluminum alloy material to respectively obtain a plastic material and a second aluminum alloy material; carrying out reselection and impurity removal on the second aluminum alloy material to respectively obtain impure metals and a refined aluminum alloy material; and carrying out photoelectric separation on the refined aluminum alloy material to respectively obtain highly refined aluminum alloy products having different grades, wherein the photoelectric selection comprises photoelectric separation based on laser-induced breakdown spectroscopy.

Description

A method for recycling scrap aluminum

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202311029102.1, filed on August 15, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to the field of comprehensive recycling of solid waste, and in particular to a method for recycling scrap aluminum while preserving its grade. Background Art

[0004] According to statistics, the global production of recycled aluminum is 35.83 million tons, accounting for 14% of the original aluminum production, while the domestic production of recycled aluminum is 7.65 million tons, accounting for 19.9% ​​of the original aluminum production; at the same time, the rapid growth of domestic aluminum consumption has continued for nearly 20 years. According to the 20-30 year service life cycle of aluminum products, a large amount of scrap aluminum resources will flood into the market in the next few years, and the demand for comprehensive utilization technology of scrap aluminum resources will increase accordingly.

[0005] However, at present, domestic scrap aluminum recycling is still mainly based on mixed smelting, and aluminum alloys are not classified, which is downgraded recycling. There are problems such as low impurity removal efficiency, no classification and separation, and downgraded recycling. At present, in the recycling process of powdered scrap aluminum in other developed countries, grade-keeping recycling is the main method, and research on upgraded recycling technology has begun. Therefore, in terms of scrap aluminum recycling, there is a clear gap between the traditional domestic recycling methods and the current grade-keeping recycling technology, and related technologies are in urgent need of breakthroughs in order to achieve efficient and high-value utilization of scrap aluminum resources.

[0006] In addition, the mixed smelting scrap aluminum recycling method has the disadvantages of high impurity removal cost, low impurity removal efficiency and high energy consumption. Therefore, it is currently necessary to develop a method for separating and classifying aluminum alloys according to different grades for recycling, so as to achieve grade-preserving recycling of scrap aluminum and improve the recycling rate of scrap aluminum.

[0007] Summary of the Invention

[0008] By utilizing one or more embodiments of the present disclosure, the technical problem in the prior art of recycling scrap aluminum using mixed smelting, in which it is difficult to separate and classify aluminum alloys according to different grades for recycling, is solved.

[0009] According to some embodiments of the present disclosure, a method for grade-preserving recycling of scrap aluminum is provided, the method comprising: crushing scrap aluminum alloy material to a preset particle size to obtain a crude aluminum alloy material; subjecting the crude aluminum alloy material to magnetic separation and impurity removal to obtain an iron product material and a first aluminum alloy material, respectively; subjecting the first aluminum alloy material to electrostatic separation and impurity removal to obtain a plastic material and a second aluminum alloy material, respectively; subjecting the second aluminum alloy material to gravity separation and impurity removal to obtain an impurity metal and a sub-fine aluminum alloy material, respectively; and subjecting the sub-fine aluminum alloy material to photoelectric separation to obtain refined aluminum alloy products of different grades, respectively; wherein the photoelectric separation comprises photoelectric separation by laser induced breakdown spectroscopy sorting. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0011] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0012] FIG1 shows a schematic flow chart of a method for recycling scrap aluminum with guaranteed grade according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0013] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present disclosure without making any creative efforts shall fall within the scope of protection of the present disclosure.

[0014] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present disclosure can be purchased from the market or prepared by existing methods.

[0015] The creative thinking of this disclosure is:

[0016] The current recycling technologies for scrap aluminum alloys are:

[0017] (1) A waste aluminum recycling process, which involves two parts: pretreatment and smelting. After simple pretreatment, the waste aluminum is not classified and recycled, but the aluminum alloy is purified and then directly put into the smelting furnace. This method has the disadvantages of high energy consumption, high labor cost, low aluminum alloy classification rate, and low comprehensive resource utilization rate.

[0018] (2) A scrap aluminum recycling, sorting and impurity removal device, which only realizes the automation of scrap aluminum impurity removal and improves the scrap aluminum sorting efficiency, but does not realize the classified recycling of scrap aluminum;

[0019] (3) A waste aluminum impurity purification device, which is a smelting and purification device that removes impurities during the aluminum alloy smelting process. The device has high energy consumption, high operating costs, and low aluminum alloy recovery rate.

[0020] The above-mentioned recycling technology is mainly in the mixed smelting recovery stage, without classifying the aluminum alloy, which is downgraded recycling, reducing the recycling rate of the aluminum alloy. In addition, mixed smelting has problems such as high impurity removal cost, low impurity removal efficiency, and high energy consumption. Therefore, the present disclosure proposes a method for separating and classifying aluminum alloys according to different grades for recycling, thereby improving the recycling rate of scrap aluminum and achieving grade-preserving recycling of scrap aluminum. The method has the characteristics of simple process, convenient operation, low energy consumption, low production cost, high recovery rate, strong process adaptability, stable production, high comprehensive utilization rate, and environmental friendliness. In addition, this method is the first time that laser-induced breakdown spectroscopy technology has been applied to the field of scrap aluminum recycling in China, which can achieve grade-preserving recycling of scrap aluminum and fill the technical gap in the domestic scrap aluminum recycling industry.

[0021] As shown in FIG1 , a method for recycling scrap aluminum according to some embodiments of the present disclosure includes:

[0022] S1. Crushing waste aluminum alloy materials to a preset particle size to obtain crude aluminum alloy materials;

[0023] S2. The crude aluminum alloy material is subjected to magnetic separation to remove impurities, respectively, to obtain an iron product material and a first aluminum alloy material;

[0024] S3. The first aluminum alloy material is subjected to electric separation to remove impurities, respectively, to obtain a plastic material and a second aluminum alloy material;

[0025] S4. Reselecting the second aluminum alloy material to remove impurities and obtain impurity metals and sub-refined aluminum alloy materials; and,

[0026] S5. The secondary refined aluminum alloy material is subjected to photoelectric selection to obtain different grades of refined aluminum alloy products;

[0027] The photoelectric selection includes photoelectric selection by laser induced breakdown spectroscopy sorting.

[0028] In the embodiment of the present disclosure, by introducing the laser induced breakdown spectroscopy sorting method, photoelectric sorting operation is performed, which can eliminate the need for surface treatment of the raw materials and can sort them according to the type and content of elements. Therefore, accurate screening of sub-refined aluminum alloy materials can be achieved, thereby separating refined aluminum alloy materials of different grades.

[0029] In some optional embodiments, the preset particle size is 100 mm to 150 mm.

[0030] In the embodiment of the present disclosure, the preset particle size is controlled to be 100mm~150mm, which can improve the recovery rate of scrap aluminum alloy; if the particle size of the crushed scrap aluminum alloy material is less than 100mm, the recovery rate of aluminum will be reduced; if the particle size of the crushed scrap aluminum alloy material is greater than 150mm, some mixed impurities will be difficult to separate by crushing, such as the nylon insulation strips embedded in the broken bridge aluminum, which are difficult to separate and remove. For example, some links of the aluminum alloy are composed of impurity metals such as iron, zinc, and copper, which are not suitable for crushing and separation, resulting in the inability to separate the impurity metals in the subsequent process; therefore, the preset particle size of the crushed scrap aluminum alloy material can be 100mm~150mm.

[0031] The preset particle size can be 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, or 150 mm.

[0032] In some optional embodiments, the rotor speed used for the crushing is 500 r / min to 600 r / min.

[0033] In the embodiment of the present disclosure, the crushing force can be controlled by controlling the rotor speed used for crushing. Since the rotor speed is inversely proportional to the crushed particle size, the greater the rotor speed, the smaller the crushed particle size of the scrap aluminum material. Since the crushed particle size needs to be controlled within the range of 100mm to 150mm, the rotor speed of the crusher needs to be controlled within 500r / min to 600r / min.

[0034] The rotor speed can be 500r / min, 510r / min, 520r / min, 530r / min, 540r / min, 550r / min, 560r / min, 570r / min, 580r / min, 590r / min, or 600r / min.

[0035] In some optional embodiments, the magnetic induction intensity of the magnetic separation and impurity removal is 4500Gs to 5000Gs.

[0036] In the embodiment of the present disclosure, the magnetic induction intensity of the magnetic separation and impurity removal is controlled to be 4500Gs~5000Gs, which can improve the magnetic separation efficiency. Since the crushed material may be mixed with iron impurities, weak magnetism cannot remove these entrained iron impurities, so the magnetic induction intensity of the magnetic separator is 2000Gs~3000Gs higher than that of a normal iron remover.

[0037] The magnetic induction intensity can be 4500Gs, 4600Gs, 4700Gs, 4800Gs, 4900Gs, or 5000Gs.

[0038] In some optional embodiments, the material transmission speed of the electrostatic separation and impurity removal may be 2.0 m / s to 2.6 m / s, and the rotation speed of the magnetic roller of the electrostatic separation and impurity removal may be 2900 r / min to 3100 r / min.

[0039] In the disclosed embodiment, the equipment used for electrostatic separation and impurity removal can be an eccentric eddy current separator, which can be used to separate a small amount of iron-containing metal materials to reduce the equipment damage rate. At the same time, by controlling the material transmission speed and magnetic roller speed of the electrostatic separation and impurity removal, non-ferrous metals (aluminum, copper, zinc, etc.) can be thrown out along the belt head. An appropriate magnetic wrap angle (for example, 35°) can ensure that the parabola of the material thrown out is larger, thereby improving the sorting efficiency.

[0040] The material transmission speed can be 2.0m / s, 2.1m / s, 2.2m / s, 2.3m / s, 2.4m / s, 2.5m / s, or 2.6m / s.

[0041] The rotation speed of the magnetic roller can be 2900 r / min, 2950 r / min, 3000 r / min, 3050 r / min, or 3100 r / min.

[0042] In some optional embodiments, the gravity separation medium used for gravity separation and impurity removal includes at least one of diiodomethane, sodium polytungstate, zinc chloride, calcium chloride, sodium silicate, water and ferrosilicon powder;

[0043] The particle size of the ferrosilicon powder is ≤0.038 mm.

[0044] In the embodiment of the present disclosure, the gravity separation medium for gravity separation is limited to at least one of diiodomethane, sodium polytungstate, zinc chloride, calcium chloride, sodium silicate, water and ferrosilicon powder, which can improve the screening ability of gravity separation for impurity metals, and make the heavy medium recyclable and save costs.

[0045] In some optional embodiments, when the second aluminum alloy material is subjected to gravity separation and impurity removal, that is, when the second aluminum alloy material and other metals with high density are screened, the separation density used for the gravity separation and impurity removal is 2.8 g / cm 3 ~3.2g / cm 3 .

[0046] In the embodiment of the present disclosure, the separation density used for gravity separation and impurity removal is controlled to be 2.8 g / cm 3 ~3.2g / cm 3 , because the density of aluminum alloy is about 2.7g / m 3 Within this sorting density, the aluminum alloy can be effectively separated from metals with a higher density than it to purify the aluminum alloy.

[0047] The sorting density can be 2.8g / cm 3 , or 2.9g / cm 3 , or 3.0g / cm 3 , or 3.1g / cm 3 , or 3.2g / cm 3

[0048] In some optional embodiments, the mesh size of the sieve used for the gravity separation and impurity removal is 0.5 mm to 1 mm.

[0049] In the embodiment of the present disclosure, the aperture of the screen used for gravity separation and impurity removal is controlled to be 0.5mm~1mm. On the one hand, the impurity metals can be blocked outside the screen to obtain pure semi-refined aluminum alloy materials. On the other hand, the heavy medium can be recycled within the aperture of the screen to save costs. When the aperture of the screen is too fine, it is not conducive to removing the medium, resulting in serious loss of heavy medium and increased gravity separation costs.

[0050] In some optional embodiments, the material transmission speed of the photoelectric selection is 2m / s to 5m / s.

[0051] In some optional embodiments, the number of channels of the photoelectric selection is 1 to 4.

[0052] In the embodiment of the present disclosure, the material transmission speed of the photoelectric selection is controlled to be 2m / s~5m / s, and the number of channels of the photoelectric selection is controlled to be 1~4, which can improve the sorting accuracy of the photoelectric selection; when the material transmission speed of the photoelectric selection is below 2m / s, the sorting efficiency will be reduced. When the material transmission speed of the photoelectric selection is above 5m / s, since the laser induced breakdown spectroscopy sorting machine used in the photoelectric selection requires a certain amount of time to analyze the material, although an excessively fast transmission speed can improve the sorting efficiency, an excessively fast material transmission speed will cause the equipment to respond untimely, resulting in a decrease in accuracy.

[0053] The material transmission speed of the photoelectric selection can be 2m / s, 3m / s, 4m / s, or 5m / s.

[0054] The number of channels of the photoelectric selection can be 1, 2, 3, or 4.

[0055] The technical solutions of the present disclosure are further described below in conjunction with specific examples. It should be understood that these examples are intended only to illustrate the present disclosure and are not intended to limit the scope of the present disclosure. Experimental methods in the following examples where specific conditions are not specified are generally measured in accordance with national standards. If there are no corresponding national standards, the methods are carried out in accordance with commonly used international standards, conventional conditions, or conditions recommended by the manufacturer.

[0056] Example 1

[0057] Aluminum alloy profiles of 1060, 2A12, 2017, 2A14, 3003, 5052, 5083, 5052, 6061, 6083, 6082, 7075, 7075, 7A04, aluminum alloy insulated aluminum doors and windows, and other metal profiles with impure pure minerals (plastic barrels, paper boxes, iron pipes, iron sheets, copper coils, copper pipes, lead-zinc blocks, etc.) were collected for pure mineral experiments.

[0058] The collected materials are mixed and crushed using a metal crusher with a rotor speed of 500 r / min to obtain iron products and crude aluminum alloy materials;

[0059] The obtained crude aluminum alloy material is subjected to magnetic separation and iron removal using a drum permanent magnet magnetic separator with a magnetic induction intensity of 4500 Gs to obtain a first aluminum alloy material;

[0060] The obtained first aluminum alloy material was electrostatically separated and impurities were removed by an eccentric eddy current separator. The material transmission speed of the electrostatic separator was adjusted to 2.0 m / s, a magnetic roller with a magnetic package angle of 35° was selected, and the rotation speed was 3000 r / min to obtain plastic and a second aluminum alloy material;

[0061] The second aluminum alloy material is re-selected to remove impurities, and then flotated in a non-transmission flotation tank. A suspension of ferrosilicon powder and water is used as the separation medium, and the density is adjusted to 3.0g / m 3 , obtaining a semi-refined aluminum alloy material;

[0062] The resulting semi-refined aluminum alloy material was then precisely photoelectrically sorted using a laser-induced breakdown spectroscopy (LIBS) sorter. The material transport speed was 3 m / s, and the number of channels was selected to be four, resulting in aluminum alloy products of varying grades. The products obtained from each step of this method were analyzed, and the results are shown in Table 1.

[0063] Table 1

[0064] Example 2

[0065] Comparing Example 2 with Example 1, the difference between Example 2 and Example 1 is:

[0066] The scrap aluminum alloy material obtained in Example 1 was subsequently processed as follows:

[0067] The collected materials are mixed and crushed using a metal crusher with a rotor speed of 600 r / min to obtain iron products and crude aluminum alloy materials;

[0068] The obtained crude aluminum alloy material is subjected to magnetic separation and iron removal using a drum permanent magnet magnetic separator with a magnetic induction intensity of 4500 Gs to obtain a first aluminum alloy material;

[0069] The obtained first aluminum alloy material was electrostatically separated and impurities were removed by an eccentric eddy current separator. The material transmission speed of the electrostatic separator was adjusted to 2.0 m / s, a magnetic roller with a magnetic package angle of 35° was selected, and the rotation speed was 3000 r / min to obtain plastic and a second aluminum alloy material;

[0070] The second aluminum alloy material is re-selected to remove impurities, and then flotated in a non-transmission flotation tank. A suspension of ferrosilicon powder and water is used as the separation medium, and the density is adjusted to 3.0g / m 3 , obtaining a semi-refined aluminum alloy material;

[0071] The resulting semi-refined aluminum alloy material was then precisely photoelectrically sorted using a laser-induced breakdown spectroscopy (LIBS) sorter. The material transport speed was 3 m / s, and the number of channels was selected to be four. This yielded aluminum alloy products of varying grades. The products obtained from each step of this method were analyzed, and the results are shown in Table 2.

[0072] Table 2

[0073] Example 3

[0074] Comparing Example 3 with Example 1, the difference between Example 3 and Example 1 is:

[0075] The scrap aluminum alloy material obtained in Example 1 was subsequently processed as follows:

[0076] The collected materials are mixed and crushed using a metal crusher with a rotor speed of 500 r / min to obtain iron products and crude aluminum alloy materials;

[0077] The obtained crude aluminum alloy material is subjected to magnetic separation and iron removal using a drum permanent magnet magnetic separator with a magnetic induction intensity of 5000 Gs to obtain a first aluminum alloy material;

[0078] The obtained first aluminum alloy material was electrostatically separated and impurities removed by an eccentric eddy current separator. The material transmission speed of the electrostatic separator was adjusted to 2.0 m / s, a magnetic roller with a magnetic package angle of 35° was selected, and the rotation speed was 3000 r / min to obtain a plastic and a second aluminum alloy material;

[0079] The second aluminum alloy material is re-selected to remove impurities, and then flotated in a non-transmission flotation tank. A suspension of ferrosilicon powder and water is used as the separation medium, and the density is adjusted to 3.0g / m 3 , obtaining a semi-refined aluminum alloy material;

[0080] The resulting semi-refined aluminum alloy material was subjected to precise photoelectric sorting using a laser-induced breakdown spectroscopy (LIBS) sorter. The material transmission speed was 3 m / s, and the number of channels was selected to be four, resulting in aluminum alloy products of different grades. The products obtained from each step of this method were analyzed, and the results are shown in Table 3.

[0081] Table 3

[0082] From the results in Table 3, it can be seen that although accurate sorting according to brand can be carried out, the sorting efficiency is reduced.

[0083] Example 4

[0084] Comparing Example 4 with Example 1, the difference between Example 4 and Example 1 is:

[0085] The scrap aluminum alloy material obtained in Example 1 was subsequently processed as follows:

[0086] The collected materials are mixed and crushed using a metal crusher with a rotor speed of 500 r / min to obtain iron products and crude aluminum alloy materials;

[0087] The obtained crude aluminum alloy material is subjected to magnetic separation and iron removal using a drum permanent magnet magnetic separator with a magnetic induction intensity of 4500 Gs to obtain a first aluminum alloy material;

[0088] The obtained first aluminum alloy material was electrostatically separated and impurities were removed by an eccentric eddy current separator. The material transmission speed of the electrostatic separator was adjusted to 2.5 m / s, a magnetic roller with a magnetic package angle of 35° was selected, and the rotation speed was 3000 r / min to obtain plastic and a second aluminum alloy material;

[0089] The second aluminum alloy material is re-selected to remove impurities, and then flotated in a non-transmission flotation tank. A suspension of ferrosilicon powder and water is used as the separation medium, and the density is adjusted to 3.0g / m 3 , obtaining a semi-refined aluminum alloy material;

[0090] The resulting semi-refined aluminum alloy material was subjected to precise photoelectric sorting using a laser-induced breakdown spectroscopy (LIBS) sorter. The material transmission speed was 3 m / s, and the number of channels was selected to be four, resulting in aluminum alloy products of different grades. The products obtained from each step of this method were analyzed, and the results are shown in Table 4.

[0091] Table 4

[0092] Example 5

[0093] Mixed scrap aluminum test, 50 kg of scrap aluminum collected from Baotou Aluminum Industry was used for sorting experiment.

[0094] The collected materials are mixed and crushed using a metal crusher with a rotor speed of 500 r / min to obtain iron products and crude aluminum alloy materials;

[0095] The obtained crude aluminum alloy material is subjected to magnetic separation and iron removal using a drum permanent magnet magnetic separator with a magnetic induction intensity of 4500 Gs to obtain a first aluminum alloy material;

[0096] The obtained first aluminum alloy material is electrostatically separated and impurities are removed by an eccentric eddy current separator. The material transmission speed of the electrostatic separator is adjusted to 2.5 m / s, a magnetic roller with a magnetic package angle of 35° is selected, and the rotation speed is 3050 r / min to obtain plastic and a second aluminum alloy material;

[0097] The second aluminum alloy material is re-selected to remove impurities, and then flotated in a non-transmission flotation tank. A suspension of ferrosilicon powder and water is used as the separation medium, and the density is adjusted to 3.0g / m 3 , obtaining a semi-refined aluminum alloy material;

[0098] The resulting semi-refined aluminum alloy material was subjected to precise photoelectric sorting using a laser-induced breakdown spectroscopy (LIBS) sorter. The material transmission speed was 2 m / s, and the number of channels was selected to be four, resulting in aluminum alloy products of different grades. The products obtained from each step of this method were analyzed, and the results are shown in Table 5.

[0099] Table 5

[0100] Comparative Example 1

[0101] Comparing Comparative Example 1 with Example 1, the difference between Comparative Example 1 and Example 1 is:

[0102] The scrap aluminum alloy material obtained in Example 1 was subsequently processed as follows:

[0103] The collected materials are mixed and crushed using a metal crusher with a rotor speed of 300 r / min to obtain iron products and crude aluminum alloy materials;

[0104] The obtained crude aluminum alloy material is subjected to magnetic separation and iron removal using a drum permanent magnet magnetic separator with a magnetic induction intensity of 4500 Gs to obtain a first aluminum alloy material;

[0105] The obtained first aluminum alloy material was electrostatically separated and impurities were removed by an eccentric eddy current separator. The material transmission speed of the electrostatic separator was adjusted to 2.0 m / s, a magnetic roller with a magnetic package angle of 35° was selected, and the rotation speed was 3000 r / min to obtain plastic and a second aluminum alloy material;

[0106] The second aluminum alloy material is re-selected to remove impurities, and then flotated in a non-transmission flotation tank. A suspension of ferrosilicon powder and water is used as the separation medium, and the density is adjusted to 3.0g / m 3 , obtaining a semi-refined aluminum alloy material;

[0107] The resulting semi-refined aluminum alloy material was then precisely photoelectrically sorted using a laser-induced breakdown spectroscopy (LIBS) sorter. The material transport speed was 3 m / s, and the number of channels was selected to be four. This yielded aluminum alloy products of varying grades. The products obtained from each step of this method were analyzed, and the results are shown in Table 6.

[0108] Table 6

[0109] Comparative Example 2

[0110] Comparing Comparative Example 2 with Example 5, the difference between Comparative Example 2 and Example 5 is:

[0111] The scrap aluminum recycling process disclosed in CN108823412 was used to sort the scrap aluminum collected by Baotou Aluminum Industry in Example 5. The results showed that only impurity metals such as plastic, iron, copper, and zinc could be removed from the scrap aluminum, and the aluminum alloy could not be accurately classified and sorted according to different grades, and the grade-preserving recycling of the scrap aluminum could not be achieved.

[0112] Comparative Example 3

[0113] Comparing Comparative Example 3 with Example 1, the difference between Comparative Example 3 and Example 1 is:

[0114] The scrap aluminum alloy material obtained in Example 1 was subsequently processed as follows:

[0115] The collected materials are mixed and crushed using a metal crusher with a rotor speed of 500 r / min to obtain iron products and crude aluminum alloy materials;

[0116] The obtained crude aluminum alloy material is subjected to magnetic separation and iron removal using a drum permanent magnet magnetic separator with a magnetic induction intensity of 4500 Gs to obtain a first aluminum alloy material;

[0117] The obtained first aluminum alloy material was electrostatically separated and impurities were removed by an eccentric eddy current separator. The material transmission speed of the electrostatic separator was adjusted to 2.5 m / s, a magnetic roller with a magnetic package angle of 35° was selected, and the rotation speed was 3000 r / min to obtain plastic and a second aluminum alloy material;

[0118] The second aluminum alloy material is re-selected to remove impurities, and then flotated in a non-transmission flotation tank. A suspension of ferrosilicon powder and water is used as the separation medium, and the density is adjusted to 3.0g / m 3 , obtaining a semi-refined aluminum alloy material;

[0119] The resulting semi-refined aluminum alloy material was subjected to precise photoelectric sorting using a laser-induced breakdown spectroscopy (LIBS) sorter. The material transport speed was 6 m / s, and the number of channels was selected to be four. This yielded aluminum alloy products of varying grades. The products obtained from each step of this method were analyzed, and the results are shown in Table 7.

[0120] Table 7

[0121] As shown in Table 7, due to the excessively fast transmission of the photoelectrically selected materials, the laser light source of the laser-induced breakdown spectroscopy sorter failed to break down in time, thus missing the analysis. As a result, the materials only passed through the machine once without being sorted.

[0122] According to some embodiments of the present disclosure, the method for grade-preserving recycling of scrap aluminum comprises the following steps: first, the scrap aluminum material is crushed according to a preset particle size to obtain a crude aluminum alloy material; then, the crude aluminum alloy material is subjected to magnetic separation and electrostatic separation for impurity removal in sequence; the iron impurities and aluminum alloy in the crude aluminum alloy material can be screened out to obtain a second aluminum alloy material; then, the second aluminum alloy material is subjected to gravity separation for impurity removal to achieve grading of the second aluminum alloy material to obtain a semi-refined aluminum alloy material; finally, the semi-refined aluminum alloy material is accurately sorted by photoelectric selection to obtain refined aluminum alloy materials of different grades; compared with traditional mixed smelting, the impurity removal and composition adjustment processes are reduced, thereby reducing the energy consumption of the scrap aluminum recycling and smelting process, improving the recycling rate of scrap aluminum, and realizing efficient and comprehensive utilization of scrap aluminum resources; and for the first time in China, laser-induced breakdown spectroscopy (LIBS) technology is used in the field of scrap aluminum recycling, realizing the separation and classification of scrap aluminum alloys according to different grades for recycling, thereby solving the problems of low impurity removal efficiency, lack of classification and separation, and downgraded recycling in the current scrap aluminum recycling process.

[0123] To sum up, according to the method of grade-preserving recycling of scrap aluminum in some embodiments of the present disclosure, scrap aluminum alloy materials can be separated and classified for recycling according to different brands, and grade-preserving recycling of scrap aluminum can be achieved. It can not only help achieve energy conservation and emission reduction and realize the dual carbon goals, but also promote the green economic and high-quality development of the aluminum industry, so as to achieve the goal of efficient and comprehensive utilization of scrap aluminum resources, which is of great significance to promoting the green, low-carbon, circular and efficient development of the aluminum industry.

[0124] Various embodiments of the present disclosure may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a hard limit on the scope of the present disclosure; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0125] In the present disclosure, unless otherwise specified, the directional words used, such as "upper" and "lower", specifically refer to the directions of the drawings in the accompanying drawings. In addition, in the description of the present disclosure, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" refers to one or more, and "plurality" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple.

[0126] The foregoing description is intended only to provide specific embodiments of the present disclosure, which will enable those skilled in the art to understand and implement the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the embodiments shown herein, but rather to be construed in the broadest manner consistent with the principles and novel features disclosed herein.

Claims

1. A method for recycling scrap aluminum with guaranteed grade, comprising: Crushing waste aluminum alloy materials into a preset particle size to obtain crude aluminum alloy materials; The crude aluminum alloy material is subjected to magnetic separation to remove impurities, and an iron product material and a first aluminum alloy material are obtained respectively; Electrostatically separating and removing impurities from the first aluminum alloy material to obtain a plastic material and a second aluminum alloy material respectively; Reselecting and removing impurities from the second aluminum alloy material to obtain impurity metal and sub-refined aluminum alloy material; and, Performing photoelectric separation on the sub-refined aluminum alloy material to obtain refined aluminum alloy products of different grades; The photoelectric selection includes photoelectric selection by laser induced breakdown spectroscopy sorting.

2. The method according to claim 1, wherein: The preset particle size is 100 mm to 150 mm.

3. The method according to claim 1, wherein: The rotor speed used for the crushing is 500r / min to 600r / min.

4. The method according to claim 1, wherein: The magnetic induction intensity of the magnetic separation and impurity removal is 4500Gs to 5000Gs.

5. The method according to claim 1, wherein: The material transmission speed of the electrostatic separation and impurity removal is 2.0m / s to 2.6m / s, and the rotation speed of the magnetic roller of the electrostatic separation and impurity removal is 2900r / min to 3100r / min.

6. The method according to claim 1, wherein: The gravity separation medium used for gravity separation and impurity removal includes at least one of diiodomethane, sodium polytungstate, zinc chloride, calcium chloride, sodium silicate, water and ferrosilicon powder; The particle size of the ferrosilicon powder is ≤0.038 mm.

7. The method according to claim 6, wherein: The separation density used for the gravity separation is 2.8 g / cm 3 ~32g / cm 3 .

8. The method according to claim 6, wherein: The mesh size of the sieve used for gravity separation and impurity removal is 0.5 mm to 1 mm.

9. The method according to claim 1, wherein: The material transmission speed of the photoelectric selection is 2m / s to 5m / s.

10. The method according to claim 9, wherein: The number of channels of the photoelectric selection is 1-4.

Images