Recovery method of aluminum-based solid waste

Abstract

The invention belongs to the technical field of solid waste recycling, and provides an aluminum-based solid waste recycling method which comprises the steps that a first acid solution containing sulfuric acid and aluminum-based solid waste are mixed for acid pickling, and a first mixed solution is obtained; filtering the first mixed solution to obtain a filter cake, mixing a first alkaline solution with the filter cake, and performing alkali dissolution to obtain a second mixed solution; filtering the second mixed solution to obtain a filtrate, mixing the filtrate with a template agent to obtain a third mixed solution, and adding a second acidic solution into the third mixed solution to adjust the pH value to obtain a precipitate; calcining the precipitate to obtain a first aluminum oxide mixture; furthermore, the first aluminum oxide mixture is subjected to precision treatment, so that aluminum oxide powder can be obtained. The recovery method is high in dissolution efficiency, high in product purity and high in specific surface area.

Description

Technical Field

[0001] The present application relates to the technical field of solid waste recycling, and in particular to a method for recycling aluminum-based solid waste. Background Art

[0002] At present, the aluminum-containing substances in solid waste are mainly recycled by alkaline dissolution. Through alkaline dissolution, useful components such as aluminum oxide in aluminum-containing solid waste can be converted into reusable aluminum hydroxide or other compounds, thereby achieving the purpose of solid waste resource utilization. However, in traditional technologies, directly mixing aluminum-based waste with alkaline solution to dissolve aluminum elements has problems such as low dissolution efficiency and low product purity. Summary of the invention

[0003] Based on this, an embodiment of the present application provides a method for recycling aluminum-based solid waste with high dissolution efficiency and high product purity.

[0004] The present application provides a method for recycling aluminum-based solid waste, and the method for recycling aluminum-based solid waste comprises:

[0005] Mixing a first acidic solution containing sulfuric acid and aluminum-based solid waste for pickling to obtain a first mixed solution;

[0006] Filtering the first mixed solution to obtain a filter cake, mixing the first alkaline solution and the filter cake, and dissolving with alkali to obtain a second mixed solution;

[0007] Filtering the second mixed solution to obtain a filtrate, mixing the filtrate with a template to obtain a third mixed solution, and adding a second acidic solution to the third mixed solution to adjust the pH to obtain a precipitate;

[0008] The precipitate is calcined to obtain a first alumina mixture.

[0009] In some embodiments, the first acidic solution further contains a chloride salt.

[0010] Optionally, the mass concentration of chloride salt in the first acidic solution is 50 g / L~70 g / L.

[0011] Optionally, the chloride salt includes at least one of sodium chloride, aluminum chloride and magnesium chloride.

[0012] In some embodiments, the mass concentration of sulfuric acid in the first acidic solution is 80 g / L to 120 g / L.

[0013] In some embodiments, the alkaline substance contained in the first alkaline solution includes sodium hydroxide.

[0014] In some embodiments, the mass concentration of the alkaline substance in the first alkaline solution is 15% to 25%.

[0015] In some embodiments, the template comprises polyethylene glycol. Optionally, the number average molecular weight of the polyethylene glycol is 1500-2500.

[0016] In some embodiments, the second acidic solution contains hydrochloric acid. Optionally, the mass concentration of hydrochloric acid in the second acidic solution is 5% to 20%.

[0017] In some embodiments, the alkali dissolution is carried out at a temperature of 150° C. to 200° C. and for a time of 4 h to 6 h.

[0018] In some embodiments, the pH of the third mixed solution after adding the second acidic solution is 7.5-8.5.

[0019] In some embodiments, the calcination temperature is 450° C. to 600° C., and the calcination time is 1 h to 3 h.

[0020] In some embodiments, the mass ratio of the first acidic solution to the aluminum-based solid waste is (4-6):1.

[0021] In some embodiments, the ratio of the mass of the alkaline substance contained in the first alkaline solution to the mass of the aluminum-based solid waste is (0.8~1.2):1.

[0022] In some embodiments, the ratio of the mass of the template to the mass of the aluminum-based solid waste is (0.5~1.0):1.

[0023] In some embodiments, the first alumina mixture is subjected to fine treatment to obtain alumina powder, and the fine treatment method includes:

[0024] Mixing the first alumina mixture with a penetrant to obtain a second alumina mixture;

[0025] Mixing the second aluminum oxide mixture and a sodium removal agent solution to obtain a fourth mixed solution;

[0026] The fourth mixed liquid is filtered to obtain aluminum oxide powder.

[0027] In some embodiments, the second alumina mixture and the sodium-removing agent solution are mixed by at least one method selected from the group consisting of ultrasound, shaking, and stirring.

[0028] In some embodiments, the first alumina mixture and the infiltrant are mixed by at least one of ball milling, vibration milling, and mechanical impact milling.

[0029] In some embodiments, the sodium-removing agent contained in the sodium-removing agent solution includes acetic acid.

[0030] In some embodiments, the molar concentration of the sodium removal agent in the sodium removal agent solution is 8 mol / L to 10 mol / L.

[0031] In some embodiments, the osmotic agent includes at least one of citric acid and oxalic acid.

[0032] In some embodiments, the mass ratio of the first alumina mixture to the infiltrant is (0.8-1.2):1.

[0033] In some embodiments, the mass ratio of the sodium removal agent solution to the second alumina mixture is (5-7):1.

[0034] Compared with the traditional technology, this application has at least the following beneficial effects:

[0035] The present application uses a first acidic solution containing sulfuric acid to pickle the aluminum-based solid waste solution. The aluminum element reacts with sulfuric acid to form aluminum oxide, and sulfuric acid is difficult to react with aluminum oxide. During the pickling process, metal impurity elements in the aluminum-based solid waste, such as bismuth, iron, copper and gallium, can be removed, which not only improves the aluminum purity in the aluminum-based solid waste, but also the aluminum-based solid waste after pickling has high alkali dissolution efficiency. Further, by synergistically adjusting the second acidic solution and the template agent, the silicon element can be removed, and the particle size of the aluminum hydroxide precipitate can be refined, and the specific surface area can be controlled, so as to calcine to obtain a first aluminum oxide mixture with high purity. In addition, the present application further refines the first aluminum oxide mixture, and coordinates and cooperates with multiple methods such as adding a penetrant and a sodium removal agent, ball milling, ultrasonic pickling and hot water washing to obtain a high-purity, high-specific surface area aluminum oxide powder with a particle size of 2μm~6μm. The present application can effectively improve the alkali dissolution efficiency of aluminum-based solid waste, and the aluminum oxide formed has a small particle size and high purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic flow chart of a method for recycling aluminum-based solid waste provided in one embodiment of the present application.

[0037] Figure 2 This is a SEM image of the alumina powder recovered in Example 1 of the present application.

[0038] Figure 3 This is the XRD diagram of the alumina powder recovered in Example 1 of the present application.

[0039] Figure 4 This is the particle size distribution diagram of the alumina powder recovered in Example 1 of the present application.

[0040] Figure 5 This is the particle size distribution diagram of the alumina powder recovered in Example 2 of the present application.

[0041] Figure 6 This is the XRD diagram of the alumina powder recovered in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0042] Below in conjunction with the embodiments and examples, the present application is further described in detail. These embodiments and examples are only used to illustrate the present application and are not used to limit the scope of the present application. The purpose of providing these embodiments and examples is to make the understanding of the disclosure of the present application more thorough and comprehensive. It should also be understood that the present application can be implemented in many different forms, and is not limited to the embodiments and examples described herein. Those skilled in the art can make various changes or modifications without violating the connotation of the present application, and the equivalent form obtained also falls within the protection scope of the present application. In addition, in the description below, a large number of specific details are given in order to provide a more comprehensive understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0044] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0045] In this application, the terms "first", "second", etc. in "the first aspect", "the second aspect", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0046] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0047] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical range disclosed in the present application should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows for a broad range of quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0048] All documents mentioned in this application are cited as references in this application, just as each document is cited as reference separately. Unless they conflict with the application purpose and / or technical solution of this application, the cited documents involved in this application are cited with all contents and all purposes. When the cited documents are involved in this application, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When the cited documents are involved in this application, the examples and preferred methods of the cited relevant technical features can also be incorporated into this application as references, but are limited to the implementation of this application. It should be understood that when the cited content conflicts with the description in this application, the present application shall prevail or be modified adaptively according to the description of this application.

[0049] In traditional technology, aluminum-based solid waste is directly dissolved in alkali, which not only easily dissolves other metal element impurities and affects the purity of the product, but also has low alkali dissolution efficiency, and the alumina particles formed are larger and have a smaller specific surface area.

[0050] The present application provides a method for recycling aluminum-based solid waste, such as Figure 1 As shown, the method for recycling aluminum-based solid waste includes:

[0051] Mixing a first acidic solution containing sulfuric acid and aluminum-based solid waste for pickling to obtain a first mixed solution;

[0052] Filtering the first mixed solution to obtain a filter cake, mixing the first alkaline solution and the filter cake, and dissolving with alkali to obtain a second mixed solution;

[0053] Filtering the second mixed solution to obtain a filtrate, mixing the filtrate with a template to obtain a third mixed solution, and adding a second acidic solution to the third mixed solution to adjust the pH to obtain a precipitate;

[0054] The precipitate is calcined to obtain a first alumina mixture.

[0055] The present application uses a first acidic solution containing sulfuric acid to pickle the aluminum-based solid waste solution. The aluminum element reacts with sulfuric acid to form aluminum oxide, and sulfuric acid and aluminum oxide are difficult to react. During the pickling process, metal impurity elements in the aluminum-based solid waste, such as bismuth, iron, copper and gallium, can be removed, which not only improves the aluminum purity in the aluminum-based solid waste, but also increases the efficiency of alkaline dissolution of the aluminum-based solid waste after pickling. Furthermore, through the coordinated adjustment of the second acidic solution and the template agent, the silicon element can be removed, and the particle size of the aluminum hydroxide precipitate can be refined, and the specific surface area can be controlled, so as to calcine to obtain a first aluminum oxide mixture with high purity. The present application can effectively improve the alkaline dissolution efficiency of aluminum-based solid waste, and the aluminum oxide formed has a small particle size and high purity.

[0056] In some embodiments, the first acidic solution further contains chloride salt. Since sulfuric acid reacts with aluminum, a dense aluminum oxide film may be formed on the surface of the aluminum-based solid waste, which affects the removal effect of metal impurity atoms. Therefore, the present application adds chloride salt to the first acidic solution. The introduction of chloride ions can avoid the formation of aluminum oxide film and promote the dissolution of metal impurity atoms. For example, chloride ions can promote the dissolution of bismuth oxide, thereby improving the pickling efficiency and pickling effect.

[0057] Optionally, the mass concentration of chloride salt in the first acidic solution is 50 g / L~70 g / L, for example, it can be 50 g / L, 52 g / L, 54 g / L, 56 g / L, 58 g / L, 60 g / L, 62 g / L, 64 g / L, 66 g / L, 68 g / L or 70 g / L.

[0058] Optionally, the chloride salt includes at least one of sodium chloride, aluminum chloride and magnesium chloride.

[0059] In some embodiments, the mass concentration of sulfuric acid in the first acidic solution is 80 g / L to 120 g / L, for example, 80 g / L, 84 g / L, 88 g / L, 92 g / L, 96 g / L, 100 g / L, 104 g / L, 108 g / L, 112 g / L, 116 g / L or 120 g / L.

[0060] The sulfuric acid concentration and chloride salt concentration in the first acidic solution selected in the present application as above can not only avoid the formation of aluminum oxide film, but also easily react with impurity metals such as bismuth, iron, copper and gallium and their oxides in aluminum-based solid waste, thereby improving the aluminum purity in aluminum-based solid waste, thereby accelerating the alkaline dissolution efficiency and avoiding problems such as reaction passivation.

[0061] In some embodiments, the first acidic solution and the aluminum-based solid waste are reacted in a water bath with a temperature of 60° C. to 80° C. for 1.5 h to 2.5 h.

[0062] It is understandable that the filter cake obtained by filtering the first mixed liquid is washed with water to remove the acidic solution remaining on the filter cake.

[0063] In some embodiments, the alkaline substance contained in the first alkaline solution includes sodium hydroxide.

[0064] In some embodiments, the mass concentration of the alkaline substance in the first alkaline solution is 15% to 25%, for example, it can be 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24% or 25%.

[0065] In some embodiments, the template includes polyethylene glycol. The present application uses polyethylene glycol as a template to control the particle size and specific surface area of ​​the precipitate.

[0066] Optionally, the number average molecular weight of the polyethylene glycol is 1500-2500, for example, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400 or 2500.

[0067] The number average molecular weight of polyethylene glycol selected in the present application is as above, which is conducive to inhibiting the agglomeration of alumina particles in the solution, improving the sintering activity of alumina powder obtained by calcination, and thus reducing the particle size of alumina particles. If the molecular weight of polyethylene glycol is relatively large, the polyethylene glycol molecular chain is easy to be twisted in the solution, making the movement of the colloid in water more difficult, affecting the formation of a uniform protective film on the surface of Al(OH)3 colloid particles, weakening the steric hindrance, and reducing the template effect.

[0068] In some embodiments, the second acidic solution contains hydrochloric acid. Optionally, the mass concentration of hydrochloric acid in the second acidic solution is 5% to 20%, for example, 5%, 6%, 8%, 10%, 12%, 14%, 16%, 18% or 20%.

[0069] In some embodiments, the alkali dissolution is carried out at a temperature of 150° C. to 200° C. and for a time of 4 h to 6 h.

[0070] It is understandable that the filtering method for the second mixed liquid may include the following steps:

[0071] The second mixed solution is allowed to stand, the supernatant is collected, and the supernatant is filtered to obtain a filtrate. Optionally, the supernatant is diluted with water to avoid the problem that the pH of the supernatant is high and easily damages the filter paper.

[0072] During the alkaline dissolution process, the iron oxide, copper oxide and bismuth oxide remaining in the aluminum-based solid waste do not react with sodium hydroxide and can be directly filtered out. Aluminum and silicon elements are dissolved in sodium hydroxide solution and can be separated by adjusting the pH.

[0073] In some embodiments, the pH of the third mixed solution after adding the second acidic solution is 7.5-8.5, for example, it can be 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4 or 8.5.

[0074] The present application controls the pH of the third mixed solution as described above, and can separate the silicate and metaaluminate dissolved in the alkaline dissolution process. In the process of adjusting the pH, the metaaluminate can be converted into aluminum hydroxide, while the silicate still exists as silicate ions, thereby effectively removing the silicon element. Moreover, the use of hydrochloric acid to adjust the pH can refine the particle size of the formed precipitation.

[0075] In some embodiments, the aluminum hydroxide precipitate produced after pH adjustment is collected by centrifugation.

[0076] It is understood that before calcining the precipitate, the precipitate may be washed with water and dried at a temperature of 50°C to 70°C for 5h to 7h.

[0077] In some embodiments, the calcination temperature is 450° C. to 600° C. and the calcination time is 1 h to 3 h. In the present application, the formed aluminum hydroxide precipitate is converted into aluminum oxide particles by calcination, and the aluminum oxide particles have a certain mesoporous structure.

[0078] In some embodiments, the mass ratio of the first acidic solution to the aluminum-based solid waste is (4-6):1.

[0079] In some embodiments, the ratio of the mass of the alkaline substance contained in the first alkaline solution to the mass of the aluminum-based solid waste is (0.8~1.2):1.

[0080] In some embodiments, the ratio of the mass of the template to the mass of the aluminum-based solid waste is (0.8~1.2):1.

[0081] In some embodiments, the first aluminum oxide mixture is washed with water and dried to remove residual alkali attached to the surface. The water washing temperature may be 85°C to 95°C.

[0082] In some embodiments, the first alumina mixture is subjected to fine treatment to obtain alumina powder, and the fine treatment method includes:

[0083] Mixing the first alumina mixture with a penetrant to obtain a second alumina mixture;

[0084] Mixing the second aluminum oxide mixture and a sodium removal agent solution to obtain a fourth mixed solution;

[0085] The fourth mixed liquid is filtered to obtain aluminum oxide powder.

[0086] The present application utilizes a combination of a penetrant and a sodium removal agent, which can penetrate the sodium removal agent and the penetrant into the lattice gaps of the alumina crystals, thereby fully removing the intercrystalline alkali in the alumina, further removing the sodium element in the alumina, and improving the purity of the alumina.

[0087] In some embodiments, at least one of ultrasound, shaking and stirring is used to mix the second alumina mixture and the sodium removal agent solution. Optionally, the second alumina mixture and the sodium removal agent solution are mixed ultrasonically. The present application uses ultrasound to mix the second alumina mixture and the sodium removal agent. Ultrasonic waves have the characteristics of short wavelength and concentrated energy, which can have a greater intensity of dispersion and impact on finer powders, thereby causing oscillation of water molecules in the solution, thereby penetrating into the lattice gaps of the crystals, generating a strong high-pressure shock to break the lattice and expose the intercrystalline alkali, thereby accelerating the removal efficiency of the intercrystalline alkali. Optionally, the temperature during the ultrasonic process is 50°C~90°C.

[0088] In some embodiments, the first alumina mixture and the infiltrant are mixed by at least one of ball milling, vibration milling and mechanical impact milling. The present application uses ball milling to mix the first alumina mixture and the infiltrant, so that the infiltrant citric acid and the alumina powder are fully in contact.

[0089] Optionally, the ball milling speed is 150rpm~250rpm, the time is 8h~12h, and the ball-to-material ratio is 1:(8~12).

[0090] In some embodiments, the sodium removing agent contained in the sodium removing agent solution comprises acetic acid.

[0091] In some embodiments, the molar concentration of the sodium removal agent in the sodium removal agent solution is 8 mol / L~10 mol / L, for example, it can be 8.0 mol / L, 8.2 mol / L, 8.4 mol / L, 8.6 mol / L, 8.8 mol / L, 9.0 mol / L, 9.2 mol / L, 9.4 mol / L, 9.6 mol / L, 9.8 mol / L or 10.0 mol / L.

[0092] In some embodiments, the osmotic agent includes at least one of citric acid and oxalic acid.

[0093] In some embodiments, the mass ratio of the first alumina mixture to the infiltrant is (0.8-1.2):1, for example, 0.80:1, 0.85:1, 0.90:1, 0.95:1, 1.00:1, 1.05:1, 1.10:1, 1.15:1 or 1.20:1.

[0094] In some embodiments, the mass ratio of the sodium removal agent solution to the second alumina mixture is (5-7):1, for example, 5.0:1, 5.2:1, 5.4:1, 5.6:1, 5.8:1, 6.0:1, 6.2:1, 6.4:1, 6.6:1, 6.8:1 or 7.0:1.

[0095] In some embodiments, the aluminum oxide powder obtained by filtering the fourth mixed solution is washed with water and dried. The alkali attached to the surface of the aluminum oxide powder can be removed by washing with water. Optionally, a water bath is used during the washing process, and the temperature of the water bath is 85°C to 95°C.

[0096] Exemplarily, a method for recycling the above aluminum-based solid waste is provided, comprising the following steps:

[0097] S1. Preparing a first acidic solution containing sulfuric acid and chloride salt, mixing the first acidic solution with aluminum-based solid waste, stirring and pickling in a water bath to obtain a first mixed solution, and removing impurities such as bismuth, iron, copper and gallium in the aluminum-based solid waste;

[0098] S2, filtering the first mixed solution to obtain a filter cake, washing the filter cake with water to remove the acidic solution remaining on the filter cake, mixing the filter cake with the first alkaline solution for alkali dissolution to obtain a second mixed solution, letting the second mixed solution stand, taking the upper supernatant and diluting it to obtain a filtrate, and removing impurities such as iron oxide, copper oxide and bismuth oxide that do not react with the first alkaline solution;

[0099] S3, adding a template to the filtrate to obtain a third mixed solution, adding a second acidic solution to the third mixed solution to adjust the pH, forming an aluminum hydroxide precipitate in the solution, stirring and aging, and centrifuging to obtain an aluminum hydroxide precipitate;

[0100] S4, drying the aluminum hydroxide precipitate, and calcining it to obtain a first aluminum oxide mixture;

[0101] S5, mixing the first alumina mixture with the penetrant and ball milling to obtain a second alumina mixture, then mixing the second alumina mixture with a sodium removal agent solution, and performing ultrasonic treatment to obtain a fourth mixed solution;

[0102] S6. Wash and dry the filter cake obtained after filtering the fourth mixed liquid to obtain aluminum oxide powder.

[0103] The embodiments of the present application will be described in detail below in conjunction with examples. It should be understood that these examples are only used to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are preferably referred to the guidance provided in the present application, and can also be based on the experimental manual or normal conditions in this area, can also be based on the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0104] Among them, the element content composition of aluminum-based solid waste is as follows Table 1:

[0105] Table 1

[0106]

[0107] It is understandable that due to the error of the testing equipment, the total mass of various elements in aluminum-based solid waste is approximately equal to 100%, which is a reasonable error.

[0108] Example 1

[0109] S1. Weigh 10 g of sulfuric acid and 6 g of sodium chloride and mix them with 95 mL of water to form a first acidic solution, and mix the first acidic solution with 20 g of aluminum-based solid waste, and stir and pickle in a water bath at 70° C. to obtain a first mixed solution;

[0110] S2, filtering the first mixed solution to obtain a filter cake, washing the filter cake with water, placing the filter cake in a polytetrafluoroethylene tank, mixing 20g of sodium hydroxide and 100mL of water to form a first alkaline solution, adding the first alkaline solution to the polytetrafluoroethylene tank containing the filter cake, and alkali dissolving at 180°C for 5h to obtain a second mixed solution; after the second mixed solution is allowed to stand, taking the supernatant and diluting it with the same volume of water, and filtering it to obtain a filtrate;

[0111] S3, adding 15g of polyethylene glycol 2000 to the filtrate and mixing to obtain a third mixed solution, and then adding a hydrochloric acid solution with a mass concentration of 10% to the third mixed solution to adjust the pH to 8, forming an aluminum hydroxide precipitate in the solution, stirring for 1h and standing for 12h, and then centrifuging to obtain an aluminum hydroxide precipitate;

[0112] S4, drying the aluminum hydroxide precipitate at 60° C. for 6 h, and calcining at 550° C. for 2 h to obtain a first aluminum oxide mixture;

[0113] S5, taking 15 g of the first alumina mixture and 15 g of citric acid, mixing and ball-milling, wherein the ball-milling medium is 100 g, the ball-milling speed is 200 rpm, and the time is 10 h to obtain a second alumina mixture, and then mixing the second alumina mixture with 180 mL of 6 mol / L acetic acid solution, and ultrasonically treating at 70° C. for 5 h to obtain a fourth mixed solution;

[0114] S6. The filter cake obtained after the fourth mixed solution was filtered was washed in a 90°C water bath for 30 minutes and centrifuged to obtain a precipitate. The precipitate was dried at 60°C for 12 hours to obtain alumina powder. Figure 2 As shown, the XRD pattern is Figure 3 shown.

[0115] The BET specific surface area of ​​the alumina powder prepared in this example is 129.27 m 2 / g, D50 particle size is 2.246μm, purity is 99.66%, Bi2O3 content is 0.0112%, Na2O content is reduced to 0.22%, SO3 content is 0.0295%. Particle size distribution diagram is as follows Figure 4 shown.

[0116] Example 2

[0117] Aluminum-based solid waste recycling is carried out according to the method of Example 1, except that steps S5 and S6 are not performed, that is, no fine treatment is performed, and the first alumina mixture obtained in step S4 is directly used as the recovered alumina powder.

[0118] Among them, the D50 particle size of alumina powder is 4.402μm, the purity is 99.35%, and the Na2O content is 0.46%. The particle size distribution diagram is as follows Figure 5 shown.

[0119] Example 3

[0120] Aluminum-based solid waste recovery is performed according to the method of Example 1, except that, in step S3, a sulfuric acid solution with a mass concentration of 10% is added to the third mixed solution to adjust the pH.

[0121] The D50 particle size of the alumina powder prepared in this embodiment is 5.631 μm, the purity is 95.58%, and the SO3 content is 3.4267%.

[0122] Comparative Example 1

[0123] S1. Weigh 20 g of aluminum-based solid waste and dissolve it in 100 mL of water, and stir it in a water bath at 70° C. for 2 h to obtain a first mixed solution;

[0124] S2, filtering the first mixed liquid to obtain a filter cake;

[0125] S3. Dry the filter cake at 60°C for 6 hours, and then calcine at 550°C for 2 hours to obtain alumina powder.

[0126] The BET specific surface area of ​​the alumina powder prepared in this example is 236.46 m 2 / g, total pore volume is 0.3008mL / g, average pore size is 5.0883nm, D50 particle size is 31.637μm, purity is 92.89%, and Na2O content is 1.32%. XRD diagram is shown in Figure 6 shown.

[0127] Comparative Example 2

[0128] S1. Weigh 20 g of aluminum-based solid waste and dissolve it in 100 mL of water, and stir it in a water bath at 70° C. for 2 h to obtain a first mixed solution;

[0129] S2, filtering the first mixed solution to obtain a filter cake, and washing the filter cake with water to remove the acidic solution remaining on the filter cake, placing the filter cake in a polytetrafluoroethylene tank, weighing 20g of sodium hydroxide and 100mL of water to form a first alkaline solution, adding the first alkaline solution to the polytetrafluoroethylene tank, and dissolving at 180°C for 5h to obtain a second mixed solution, after the second mixed solution is allowed to stand, taking the upper supernatant and diluting it with the same volume of water, and then filtering to obtain a filtrate;

[0130] S3, adding 15g of polyethylene glycol 2000 to the filtrate and stirring to obtain a third mixed solution, and then adding a hydrochloric acid solution with a mass concentration of 10% to the third mixed solution to adjust the pH to 8.2, forming an aluminum hydroxide precipitate in the solution, stirring for 1h and standing for 12h, and then centrifuging to obtain an aluminum hydroxide precipitate;

[0131] S4. Dry the aluminum hydroxide precipitate at 60°C for 6 hours, and then calcine at 550°C for 2 hours to obtain aluminum oxide powder.

[0132] The BET specific surface area of ​​the alumina powder prepared in this example is 134.45 m 2 / g, the total pore volume is 0.2246mL / g, the average pore size is 6.6818nm, the D50 particle size is 12.873μm, and the purity is 98.8%.

[0133] Comparative Example 3

[0134] Aluminum-based solid waste is recovered according to the method of Example 1, except that in step S1, the first acidic solution is not added for pickling, and water washing is directly used.

[0135] The purity of the alumina powder prepared in this embodiment is 98.96%, the D50 particle size is 2.639 μm, and the Bi2O3 content is 0.0245%.

[0136] Comparative Example 4

[0137] Aluminum-based solid waste recovery is carried out according to the method of Example 1, except that polyethylene glycol 2000 is not added in step S3, and the pH is directly adjusted.

[0138] The D50 particle size of the alumina powder prepared in this example is 19.508 μm, and the purity is 98.13%.

[0139] It can be seen from the above embodiments and comparative examples that:

[0140] (1) Compared with Example 1 and Example 2, it can be seen that the present application further performs a fine treatment on the first alumina mixture, generates local instantaneous energy under the cavitation effect of ultrasound combined with the dispersion effect of organic acid, further removes intergranular alkali in the alumina, improves the purity of the alumina powder, and improves the particle dispersion effect.

[0141] (2) Compared with Example 1 and Example 3, it can be seen that the present invention adds hydrochloric acid to the third mixed solution for pH adjustment, which can reduce the introduction of impurity S element compared with adding sulfuric acid solution, and at the same time, Cl - with Na + It acts as an isolation medium around Al(OH)3 to assist calcination and prevent particle agglomeration, which has the advantages of improving purity, reducing the introduction of impurity elements, and controlling particle agglomeration.

[0142] (3) Compared with Example 3, it can be seen that the present application uses the first acidic solution containing sulfuric acid and chloride ions to pickle the aluminum-based solid waste, reducing the Bi element content from 0.0245% to 0.0112%, which can improve the aluminum purity in the aluminum-based solid waste and improve the alkali dissolution efficiency. If only the first acidic solution containing sulfuric acid is used for pickling, when the concentration of sulfuric acid is high, an aluminum oxide film layer is easily formed, which covers the aluminum-based solid waste and affects the pickling effect; when the concentration of sulfuric acid is low, the removal effect of impurity metal elements is poor.

[0143] (4) Compared with Example 4, it can be seen that the present application adds a template to the upper filtrate of the second mixed solution and utilizes the steric hindrance of the template on the aluminum hydroxide colloid to make the Al(OH)3 precipitate maintain the dispersion of the powder particles and avoid particle agglomeration during the formation process, thereby reducing the particle size and reducing the intercrystalline alkali coating ratio to improve the purity.

[0144] (5) Compared with Comparative Examples 1-4, it can be seen that the present application uses a first acidic solution containing sulfuric acid to pickle the aluminum-based solid waste solution, and the aluminum element reacts with sulfuric acid to form aluminum oxide, and sulfuric acid is difficult to react with aluminum oxide. During the pickling process, metal impurity elements in the aluminum-based solid waste, such as bismuth, iron, copper and gallium, can be removed, which not only improves the aluminum purity in the aluminum-based solid waste, but also has a high efficiency in alkaline dissolution of the aluminum-based solid waste after pickling. Further, by synergistically adjusting the second acidic solution and the template agent, the silicon element can be removed, and the particle size of the aluminum hydroxide precipitate can be refined, and the specific surface area can be controlled, so as to calcine to obtain a first aluminum oxide mixture with high purity. Furthermore, by adding a penetrant and a sodium removal agent, ball milling, ultrasonic pickling and hot water washing, the first aluminum oxide mixture is finely treated to obtain a high-purity, high-specific surface area aluminum oxide powder with a particle size of 2μm~6μm. The present application can effectively improve the alkaline dissolution efficiency of aluminum-based solid waste, and the alumina particles formed are small in size and high in purity, with the purity reaching 99.66%.

[0145] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0146] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the application. It should be noted that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for recycling aluminum-based solid waste, characterized in that: The method for recycling aluminum-based solid waste comprises: Mixing a first acidic solution containing sulfuric acid and aluminum-based solid waste for pickling to obtain a first mixed solution; Filtering the first mixed solution to obtain a filter cake, mixing the first alkaline solution and the filter cake, and dissolving with alkali to obtain a second mixed solution; Filtering the second mixed solution to obtain a filtrate, mixing the filtrate with a template to obtain a third mixed solution, and adding a second acidic solution to the third mixed solution to adjust the pH to obtain a precipitate; The precipitate is calcined to obtain a first alumina mixture.

2. The method for recycling aluminum-based solid waste according to claim 1, characterized in that: The first acidic solution satisfies at least one of the following conditions: (1) The first acidic solution further contains a chloride salt; Optionally, the mass concentration of chloride salt in the first acidic solution is 50 g / L to 70 g / L; Optionally, the chloride salt includes at least one of sodium chloride, aluminum chloride and magnesium chloride; (2) The mass concentration of sulfuric acid in the first acidic solution is 80 g / L to 120 g / L.

3. The method for recycling aluminum-based solid waste according to claim 1, characterized in that: The first alkaline solution satisfies at least one of the following conditions: (1) The alkaline substance contained in the first alkaline solution includes sodium hydroxide; (2) The mass concentration of the alkaline substance contained in the first alkaline solution is 15% to 25%.

4. The method for recycling aluminum-based solid waste according to claim 1, characterized in that: The method for recycling aluminum-based solid waste meets at least one of the following conditions: (1) The template agent includes polyethylene glycol; optionally, the number average molecular weight of the polyethylene glycol is 1500-2500; (2) the second acidic solution contains hydrochloric acid; Optionally, the mass concentration of hydrochloric acid in the second acidic solution is 5% to 20%.

5. The method for recycling aluminum-based solid waste according to claim 1, characterized in that: The method for recycling aluminum-based solid waste also satisfies at least one of the following conditions: (1) The alkali dissolution temperature is 150°C to 200°C, and the time is 4h to 6h; (2) the pH of the third mixed solution after adding the second acidic solution is 7.5-8.5; (3) The calcination temperature is 450°C to 600°C, and the calcination time is 1h to 3h.

6. The method for recycling aluminum-based solid waste according to claim 1, characterized in that: The method for recycling aluminum-based solid waste also satisfies at least one of the following conditions: (1) The mass ratio of the first acidic solution to the aluminum-based solid waste is (4-6):1; (2) The ratio of the mass of the alkaline substance contained in the first alkaline solution to the mass of the aluminum-based solid waste is (0.8-1.2):1; (3) The ratio of the mass of the template to the mass of the aluminum-based solid waste is (0.5~1.0):

1.

7. The method for recycling aluminum-based solid waste according to any one of claims 1 to 6, characterized in that: The first alumina mixture is subjected to fine treatment to obtain alumina powder, wherein the fine treatment method comprises: Mixing the first alumina mixture with a penetrant to obtain a second alumina mixture; Mixing the second aluminum oxide mixture and a sodium removal agent solution to obtain a fourth mixed solution; The fourth mixed liquid is filtered to obtain aluminum oxide powder.

8. The method for recycling aluminum-based solid waste according to claim 7, characterized in that: The fine processing satisfies at least one of the following conditions: (1) mixing the second aluminum oxide mixture and the sodium removal agent solution by at least one method selected from ultrasound, shaking, and stirring; (2) Mixing the first alumina mixture and the infiltrant by at least one of ball milling, vibration milling and mechanical impact milling.

9. The method for recycling aluminum-based solid waste according to claim 7, characterized in that: The fine processing also satisfies at least one of the following conditions: (1) The sodium removal agent contained in the sodium removal agent solution includes acetic acid; (2) The sodium removal agent solution contains a sodium removal agent having a molar concentration of 8 mol / L to 10 mol / L; (3) The penetrant includes at least one of citric acid and oxalic acid.

10. The method for recycling aluminum-based solid waste according to claim 7, characterized in that: The fine processing also satisfies at least one of the following conditions: (1) The mass ratio of the first alumina mixture to the penetrant is (0.8-1.2):1; (2) The mass ratio of the sodium removal agent solution to the second alumina mixture is (5-7):1.

Images