Recycling comprehensive utilization method of secondary aluminum ash

Abstract

The invention provides a resource comprehensive utilization method of secondary aluminum ash. The method comprises the following steps: mixing secondary aluminum ash and an alkaline reactant, calcining, and collecting a first product and CO2; carrying out alkaline leaching treatment and separation on the first product, and collecting a first filtrate and a first filter residue; the first filtrate is used for preparing alumina; mixing the first filter residue with a first ammonium salt solution for hydrolysis reaction, and collecting a second product and NH3; separating the second product, and collecting a second filtrate and a second filter residue; nH3 is added with water to prepare ammonia water, the ammonia water is added into the second filtrate for a reaction, a product obtained after the reaction is separated, and a second ammonium salt solution and magnesium hydroxide are collected; magnesium hydroxide is used for preparing magnesium oxide and / or magnesium hydroxide is dissolved in water and then CO2 is introduced to prepare micro-nano hydrated magnesium carbonate. According to the method, comprehensive utilization of aluminum and magnesium resources in the secondary aluminum ash can be achieved, resource waste is reduced, and pollution of the secondary aluminum ash to the environment is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of resource recycling, and in particular to a method for comprehensive resource utilization of secondary aluminum ash. Background Art

[0002] A large amount of aluminum ash is generated during the production of aluminum products. These aluminum ash are usually regarded as waste and discarded into landfills, which not only wastes precious natural resources, but also causes serious pollution to the environment. Aluminum ash is generally divided into primary aluminum ash and secondary aluminum ash. Among them, secondary aluminum ash is a mixture of black aluminum ash and waste ash, scraps, and scraps after being recycled through salt bath treatment.

[0003] Secondary aluminum ash contains aluminum, magnesium and other components with economic value. At present, most of the treatment methods of secondary aluminum ash are aimed at recovering aluminum. For example, the patent document with publication number CN108275708A discloses a method for resource utilization of secondary aluminum ash, which uses secondary aluminum ash as raw material to prepare aluminum oxide. Although this method recycles aluminum in secondary aluminum ash, other components such as magnesium contained in secondary aluminum ash are discarded as waste and cannot be recycled, which not only wastes resources but also pollutes the environment.

[0004] Therefore, it is urgent to develop a method that can realize the comprehensive utilization of aluminum and magnesium resources in secondary aluminum ash, reduce resource waste and reduce pollution to the environment. Summary of the invention

[0005] The present invention provides a method for comprehensive resource utilization of secondary aluminum ash, which can realize the comprehensive utilization of aluminum and magnesium resources in the secondary aluminum ash, reduce resource waste, and reduce the pollution caused by the secondary aluminum ash to the environment. The method has a simple process and is suitable for wide promotion and application.

[0006] The present invention provides a method for comprehensive resource utilization of secondary aluminum ash, comprising:

[0007] The secondary aluminum ash and the alkaline reactant are mixed and then subjected to a first calcination treatment, and a first product and CO2 are collected;

[0008] performing an alkaline leaching treatment and a first separation treatment on the first product in sequence, and collecting a first filtrate and a first filter residue;

[0009] The first filtrate is used to prepare aluminum oxide;

[0010] The first filter residue is mixed with the first ammonium salt solution to perform a hydrolysis reaction, and a second product and NH3 are collected;

[0011] Performing a second separation treatment on the second product to collect a second filtrate and a second filter residue;

[0012] The NH3 is added with water to prepare ammonia water, and then added to the second filtrate for reaction, and the product after the reaction is subjected to a third separation treatment to collect a second ammonium salt solution and magnesium hydroxide;

[0013] The second ammonium salt solution is used to mix with the first filter residue to perform a hydrolysis reaction;

[0014] The magnesium hydroxide is used to prepare magnesium oxide, and / or the magnesium hydroxide is dissolved in water and then introduced into the CO2 to prepare micro-nano hydrated magnesium carbonate.

[0015] According to the resource comprehensive utilization method of secondary aluminum ash as described above, calculated by molar ratio, the molar ratio of the alkaline reactant to the aluminum oxide in the secondary aluminum ash is 0.1 to 4.

[0016] According to the resource comprehensive utilization method of secondary aluminum ash as described above, calculated by molar ratio, the molar ratio of the alkaline reactant to the aluminum oxide in the secondary aluminum ash is 1.1 to 1.4.

[0017] In the method for comprehensive resource utilization of secondary aluminum ash as described above, the alkaline reactant is at least one of sodium carbonate, sodium hydroxide, and sodium bicarbonate.

[0018] The resource comprehensive utilization method of secondary aluminum ash as described above, wherein the temperature of the first calcination treatment is 500°C to 1450°C and the time is 0.2h to 2h;

[0019] And / or, the hydrolysis reaction is carried out at a temperature of 20°C to 100°C and for a time of 0.5h to 10h.

[0020] In the above-mentioned method for comprehensive resource utilization of secondary aluminum ash, in the first ammonium salt solution, the mass ratio of ammonium salt to water is 5% to 70%.

[0021] In the above-mentioned method for comprehensive resource utilization of secondary aluminum ash, the step of using magnesium hydroxide to prepare magnesium oxide is as follows:

[0022] The magnesium hydroxide is subjected to a second calcination treatment to obtain magnesium oxide.

[0023] In the above-mentioned method for comprehensive resource utilization of secondary aluminum ash, the temperature of the second calcination treatment is 500° C. to 900° C. and the time is 1 min to 30 min.

[0024] The resource comprehensive utilization method of secondary aluminum ash as described above further comprises pre-treating the secondary aluminum ash before the first calcination treatment.

[0025] The pretreatment comprises: mixing secondary aluminum ash, a sodium source and water and reacting them to obtain a reaction product, performing a fourth separation treatment on the reaction product, and the filter residue obtained by separation is the secondary aluminum ash after the pretreatment.

[0026] According to the method for comprehensive resource utilization of secondary aluminum ash as described above, the mass ratio of the secondary aluminum ash, the sodium source and water is calculated as (50-150): (0.2-2): (150-750).

[0027] The resource comprehensive utilization method of secondary aluminum ash provided by the present invention is to mix the secondary aluminum ash and an alkaline reactant and then perform a first calcination treatment, collect the first product and CO2, perform an alkali leaching treatment and a first separation treatment on the first product, collect the first filtrate and the first filter residue; mix the first filter residue with the first ammonium salt solution for hydrolysis reaction, collect NH3 and the second product, perform a second separation treatment on the second product, and collect the second filtrate and the second filter residue. The first filtrate is used to prepare aluminum oxide; NH3 and the second filtrate are used to prepare the second ammonium salt solution and magnesium hydroxide; magnesium hydroxide is used to prepare magnesium oxide, and magnesium hydroxide and CO2 are used to prepare micro-nano hydrated magnesium carbonate. In the first aspect, the method can effectively recycle and utilize the materials (first filtrate, first filter residue, second filtrate) generated during the treatment of secondary aluminum ash, recycle NH3 and CO2, achieve a closed-loop utilization effect, realize the comprehensive utilization of aluminum and magnesium resources in secondary aluminum ash, reduce resource waste, and reduce production costs. In the second aspect, NH3 and CO2 are collected and utilized to reduce the pollution caused by gas emissions to the environment. Thirdly, the dissolution rate of aluminum oxide prepared by the method can reach 99.06%, and the dissolution rate of magnesium oxide can reach 90.27%, which can effectively recover aluminum and magnesium in secondary aluminum ash. In addition, the method is simple in process and suitable for wide promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a schematic diagram of the process of resource utilization of secondary aluminum ash in some embodiments of the present invention;

[0030] Figure 2 is the XRD diagram of the first filter residue 2 in process A2 of Example 1 of the present invention;

[0031] Figure 3is the XRD diagram of the second filter residue 2 in process B2 of Example 1 of the present invention;

[0032] Figure 4 is the XRD diagram of the precipitate 2 after drying in process B2 of Example 1 of the present invention;

[0033] Figure 5 This is a 10,000-fold SEM image of the first filter residue 2 in process A2 of Example 1 of the present invention;

[0034] Figure 6 This is a 30,000-fold SEM image of the first filter residue 2 in process A2 of Example 1 of the present invention;

[0035] Figure 7 This is a SEM image of the second filter residue 2 in process B2 of Example 1 of the present invention;

[0036] Figure 8 This is the EDS element spectrum of the rod-shaped substances on the surface of the second filter residue 2 in process B2 of Example 1 of the present invention;

[0037] Fig. 9 This is a 50,000-fold SEM image of the precipitate 2 after drying in process B2 of Example 1 of the present invention;

[0038] Fig.10 This is a 20,000-fold SEM image of the precipitate 2 after drying in process B2 of Example 1 of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Unless otherwise specified, the raw materials and reagents used in the following examples can be obtained from commercial sources; the processes used, unless otherwise specified, are conventional processes in the art.

[0041] Figure 1 The following is a schematic diagram of the process of resource utilization of secondary aluminum ash in some embodiments of the present invention. Figure 1 As shown, the present invention provides a method for comprehensive resource utilization of secondary aluminum ash, comprising:

[0042] The secondary aluminum ash and the alkaline reactant are mixed and then subjected to a first calcination treatment, and a first product and CO2 are collected;

[0043] The first product is subjected to an alkali leaching treatment and a first separation treatment in sequence, and a first filtrate and a first filter residue are collected;

[0044] The first filtrate is used to prepare alumina;

[0045] The first filter residue is mixed with the first ammonium salt solution to perform a hydrolysis reaction, and a second product and NH3 are collected;

[0046] Performing a second separation treatment on the second product to collect a second filtrate and a second filter residue;

[0047] The NH3 is added with water to prepare ammonia water, and then added to the second filtrate for reaction, and the product after the reaction is subjected to a third separation treatment to collect the second ammonium salt solution and magnesium hydroxide;

[0048] The second ammonium salt solution is used to mix with the first filter residue to perform a hydrolysis reaction;

[0049] Magnesium hydroxide is used to prepare magnesium oxide, and / or magnesium hydroxide is dissolved in water and then CO2 is introduced to prepare micro-nano hydrated magnesium carbonate.

[0050] The secondary aluminum ash of the present invention contains components such as magnesium and aluminum as well as harmful impurities such as aluminum nitride, soluble chloride salts and fluoride salts.

[0051] The present invention mixes secondary aluminum ash and an alkaline reactant and then performs a first calcination treatment. During the treatment, CO2 is released and a first product is generated. The first product and CO2 are collected. The first calcination treatment causes the secondary aluminum ash to react with the alkaline reactant to generate dissolved sodium aluminate, thereby obtaining a first product (containing dissolved sodium aluminate). The first product is then subjected to an alkali leaching treatment, which can increase the dissolution rate of aluminum oxide in the first product and dissolve more sodium aluminate and unreacted aluminum oxide. The first product after the alkali leaching treatment is then subjected to a first separation treatment. The first separation treatment is beneficial for separating a first filtrate and a first filter residue. Alumina is prepared using the first filtrate, and the first filtrate is recovered and the aluminum in the first filtrate is utilized. The first filter residue is mixed with a first ammonium salt solution for a hydrolysis reaction, which releases NH3 and generates a second product. The second product and NH3 are collected. The collected second product is then subjected to a second separation treatment. The second separation treatment is conducive to separating the second filtrate and the second filter residue; NH3 is added with water to prepare ammonia water, which is then added to the second filtrate for reaction, and the product after the reaction is subjected to the third separation treatment. The second separation treatment is conducive to separating and collecting the second ammonium salt solution and magnesium hydroxide, and the NH3 and the second filtrate are recycled; the second ammonium salt solution is used to mix with the first filter residue for hydrolysis reaction, and the second ammonium salt solution is recycled; magnesium hydroxide is used to prepare magnesium oxide, and / or, magnesium hydroxide is dissolved in water and CO2 is introduced to prepare micro-nano hydrated magnesium carbonate, and the precipitate is recycled.

[0052] The present invention does not specifically limit the methods of the first separation treatment, the second separation treatment, and the third separation treatment. In some embodiments, a suction filtration method may be used.

[0053] The present invention does not limit the specific method of preparing aluminum oxide using the first filtrate. In some embodiments, the first filtrate can be decomposed and separated using the Bayer process to collect mother liquor and aluminum hydroxide (Al(OH)3); the aluminum hydroxide is calcined to obtain aluminum oxide.

[0054] The present invention can effectively recycle and utilize the materials (first filtrate, first filter residue, second filtrate) generated during the secondary aluminum ash treatment process through the above method, cyclically utilize NH3 and CO2, achieve a closed-loop utilization effect, realize the comprehensive utilization of aluminum and magnesium resources in the secondary aluminum ash, reduce resource waste, and reduce production costs; and collect and utilize NH3 and CO2, and can also reduce the pollution caused by gas emissions to the environment. The method is simple in process and suitable for wide promotion and application.

[0055] In a specific embodiment, the molar ratio of the alkaline reactant to the alumina in the secondary aluminum ash is 0.1-4 calculated by molar ratio.

[0056] When the parameters of the molar ratio of the alkaline reactant to the alumina in the secondary aluminum ash are within the above range, alumina with a high dissolution rate can be prepared.

[0057] Illustratively, the molar ratio of the sodium source to the alumina in the secondary aluminum ash may be any one of 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5 and 4, and a range consisting of any two of them.

[0058] Furthermore, the molar ratio of the alkaline reactant to the alumina in the secondary aluminum ash is 1.1 to 1.4. When the molar ratio of the sodium source to the alumina in the secondary aluminum ash is within the above range, alumina with a higher dissolution rate can be prepared.

[0059] In a specific embodiment, the alkaline reactant is at least one of sodium carbonate, sodium hydroxide, and sodium bicarbonate.

[0060] When the alkaline reactant mentioned above is used, the secondary aluminum ash and the alkaline reactant can be mixed and then subjected to a sufficient first calcination treatment, thereby collecting more first products and CO2.

[0061] In a specific embodiment, the temperature of the first calcination treatment is 500° C. to 1450° C., and the time is 0.2 h to 2 h.

[0062] When the temperature and time parameters of the first calcination treatment are within the above range, the secondary aluminum ash and the alkaline reactant can fully react to generate more dissolved sodium aluminate, thereby improving the recovery and utilization of aluminum resources in the secondary aluminum ash.

[0063] Illustratively, the temperature of the first calcination treatment may be any one of 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C, 1300°C, 1400°C and 1450°C, and a range consisting of any two thereof;

[0064] The time may be any one of 0.2 h, 0.5 h, 1 h, 1.5 h and 2 h, or a range consisting of any two of them.

[0065] In a specific embodiment, the hydrolysis reaction is carried out at a temperature of 20°C to 100°C and a time of 0.5h to 10h.

[0066] When the reaction temperature and time parameters of the hydrolysis reaction are within the above range, harmful impurities (such as aluminum nitride, soluble chloride salts and fluoride salts, etc.) in the secondary aluminum ash can be removed efficiently, which is beneficial for the subsequent preparation of more magnesium hydroxide.

[0067] Exemplarily, the reaction temperature for the hydrolysis reaction may be any one of 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C and 100°C, and a range consisting of any two thereof;

[0068] The time may be any one of 0.5 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h and 10 h, or a range consisting of any two of them.

[0069] In a specific embodiment, in the first ammonium salt solution, the mass ratio of ammonium salt to water is 5% to 70%. Further, in the first ammonium salt solution, the mass ratio of ammonium salt to water may preferably be 15% to 45%.

[0070] When the mass ratio of the ammonium salt to the water is within the above range, magnesium oxide and / or micro-nano hydrated magnesium carbonate with a high dissolution rate can be prepared.

[0071] Illustratively, in the first ammonium salt solution, the mass ratio of ammonium salt to water may be any one of 5%, 10%, 20%, 30%, 40%, 50%, 60% and 70%, and a range consisting of any two of them.

[0072] In some embodiments, in the first ammonium salt solution, the ammonium salt is at least one of ammonium nitrate, ammonium chloride, and ammonium sulfate.

[0073] In a specific embodiment, the step of using magnesium hydroxide to prepare magnesium oxide is: performing a second calcination treatment on the magnesium hydroxide to obtain magnesium oxide.

[0074] The present invention can recycle magnesium hydroxide by performing a second calcination treatment on magnesium hydroxide, thereby preparing magnesium oxide with a high dissolution rate.

[0075] In a specific embodiment, the second calcination treatment is performed at a temperature of 500° C. to 900° C. and for a time of 1 min to 30 min.

[0076] When the parameters of the temperature and time of the second calcination treatment are within the above ranges, the magnesium hydroxide can be fully recycled to prepare magnesium oxide with a higher dissolution rate.

[0077] Exemplarily, the temperature of the second calcination treatment may be any one of 500° C., 600° C., 700° C., 800° C. and 900° C., and a range consisting of any two thereof;

[0078] The time may be any one of 1 min, 5 min, 10 min, 15 min, 20 min, 25 min and 30 min, or a range consisting of any two of them.

[0079] In a specific embodiment, the secondary aluminum ash is further pretreated before the first calcination treatment, and the pretreatment includes: mixing the secondary aluminum ash, a sodium source and water and reacting to obtain a reaction product, and performing a fourth separation treatment on the reaction product. The filter residue obtained by separation is the above-mentioned secondary aluminum ash after pretreatment.

[0080] Specifically, the secondary aluminum ash, the sodium source and water are first mixed and reacted to obtain a reaction product, and then the reaction product is subjected to a fourth separation treatment to obtain a filtrate and a filter residue, and the obtained filter residue is the pretreated secondary aluminum ash, and then the pretreated secondary aluminum ash is used as a reactant to perform a first calcination treatment. Pre-treating the secondary aluminum ash can preliminarily remove harmful impurities in the secondary aluminum ash, which is beneficial to the subsequent first calcination treatment.

[0081] In a specific implementation manner, calculated by mass ratio, the mass ratio of secondary aluminum ash, sodium source and water is (50-150): (0.2-2): (150-750).

[0082] When the mass ratio of secondary aluminum ash, sodium source and water is within the above range, more harmful impurities in the secondary aluminum ash can be removed.

[0083] Exemplarily, the mass ratio of secondary aluminum ash, sodium source and water can be any one of 50:0.2:150, 50:2:150, 50:0.2:750, 150:0.2:150, 150:2:150, 150:0.2:750 and 150:2:150, and a range consisting of any three thereof.

[0084] In a specific embodiment, the sodium source is at least one of sodium carbonate, sodium hydroxide, and sodium bicarbonate.

[0085] In a specific embodiment, the mass ratio of the first filter residue to the first ammonium salt solution is 0.1 to 1. Furthermore, the mass ratio of the first filter residue to the first ammonium salt solution may preferably be 0.2.

[0086] When the mass ratio of the first filter residue to the first ammonium salt solution is within the above range, magnesium oxide and / or micro-nano hydrated magnesium carbonate with a high dissolution rate can be prepared.

[0087] In a specific embodiment, the first filter residue is solid particles with a particle size less than 100 mesh.

[0088] When the particle size of the first filter residue is a solid phase particle with a particle size less than 100 mesh, it is beneficial for the subsequent first filter residue to be fully mixed with the ammonium salt solution for hydrolysis reaction. In some embodiments, the first filter residue can be ground to obtain a first filter residue with a solid phase particle size less than 100 mesh.

[0089] In a specific embodiment, the method further comprises: drying the first filter residue at 100° C. to 110° C. before the hydrolysis reaction. The purpose of drying the first filter residue is to remove moisture on the surface of the first filter residue, so as to fully recycle the first filter residue and improve resource utilization.

[0090] In a specific embodiment, the alkali leaching process is as follows: the first product and the first alkaline leaching agent are mixed and then alkali leached for 15 minutes at L / S=10 and 85°C, wherein the first alkaline leaching agent includes 15g / L Na2O K , concentration is 5g / L Na2O C .

[0091] The present invention performs alkali leaching treatment on the first product through the above process, thereby increasing the dissolution rate of aluminum oxide in the first product and dissolving more sodium aluminate and unreacted aluminum oxide.

[0092] In the present invention, the mother liquor can be concentrated by evaporation to obtain a second alkaline leaching agent, and the second alkaline leaching agent can be mixed with the first product for alkaline leaching treatment.

[0093] The present invention is further described below through specific embodiments.

[0094] Example 1

[0095] The resource comprehensive utilization method of secondary aluminum ash in this embodiment includes:

[0096] Pretreatment: secondary aluminum ash, sodium carbonate and water are mixed in a mass ratio of 100:1:500, reacted at 85°C for 2h, and the reaction product is separated to obtain filter residue; the filter residue is then dried at 105°C to obtain pretreated secondary aluminum ash. Then, the pretreated secondary aluminum ash is used to perform processes A1, A2, and A3 respectively.

[0097] Process A1:

[0098] The pretreated secondary aluminum ash is mixed with sodium carbonate, and the molar ratio of sodium carbonate to aluminum oxide in the pretreated secondary aluminum ash is 0.9, and then a first calcination treatment is performed at 1200° C. for 1.5 hours to release CO2 and produce a first product, and the released CO2 and the first product are collected respectively;

[0099] The first product and the first alkaline leaching agent are mixed and then subjected to alkaline leaching treatment at L / S=10 and 85°C for 15 minutes. The first alkaline leaching agent includes 15g / L Na2O K , concentration is 5g / L Na2O C ;

[0100] The mixed material is subjected to a first separation treatment to obtain a first filtrate 1 and a first filter residue 1;

[0101] Drying the first filter residue 1 at 105° C. to obtain a dried first filter residue 1;

[0102] The first filtrate 1 is decomposed and separated according to the Bayer process to obtain a mother liquor 1 and aluminum hydroxide 1; the aluminum hydroxide 1 is calcined at 1000° C. for 1 hour to obtain aluminum oxide 1.

[0103] In the present process A1, the collected CO2 can be used in the reaction of preparing micro-nano hydrated magnesium carbonate in process B3; the mother liquor 1 is evaporated and concentrated to obtain a second alkaline leaching agent 1, which can be used to mix with the first product and then perform alkaline leaching treatment.

[0104] Process A2:

[0105] The pretreated secondary aluminum ash is mixed with sodium carbonate, and the molar ratio of sodium carbonate to aluminum oxide in the pretreated secondary aluminum ash is 1.1, and then a first calcination treatment is performed at 1200° C. for 1.5 hours to release CO2 and produce a first product, and the released CO2 and the first product are collected respectively;

[0106] The first product and the first alkaline leaching agent are mixed and then subjected to alkaline leaching treatment at L / S=10 and 85°C for 15 minutes. The first alkaline leaching agent includes 15g / L Na2O K , concentration is 5g / L Na2O C ;

[0107] The mixed material is subjected to a first separation treatment to obtain a first filtrate 2 and a first filter residue 2;

[0108] Drying the first filter residue 2 at 105° C. to obtain a dried first filter residue 2;

[0109] The first filtrate 2 is decomposed and separated according to the Bayer process to obtain a mother liquor 2 and aluminum hydroxide 2; the aluminum hydroxide 2 is calcined at 1000° C. for 1 hour to obtain aluminum oxide 2.

[0110] In the process A2, the mother liquor 2 is evaporated and concentrated to obtain a second alkaline leaching agent 2, which can be mixed with the first product for alkaline leaching treatment.

[0111] Process A3:

[0112] The pretreated secondary aluminum ash is mixed with sodium carbonate, and the molar ratio of sodium carbonate to aluminum oxide in the pretreated secondary aluminum ash is 1.4, and then a first calcination treatment is performed at 1200° C. for 1.5 hours to release CO2 and produce a first product, and the released CO2 and the first product are collected respectively;

[0113] The first product and the first alkaline leaching agent are mixed and then subjected to alkaline leaching treatment at L / S=10 and 85°C for 15 minutes. The first alkaline leaching agent includes 15g / L Na2O K , concentration is 5g / L Na2O C ;

[0114] Performing a first separation treatment on the mixed material to obtain a first filtrate 3 and a first filter residue 3;

[0115] The first filter residue 3 is dried at 105° C. to obtain a dried first filter residue 3;

[0116] The first filtrate 3 is decomposed and separated according to the Bayer process to obtain a mother liquor 3 and aluminum hydroxide 3; the aluminum hydroxide 3 is calcined at 1000° C. for 1 hour to obtain aluminum oxide 3.

[0117] In the process A3, the mother liquor 3 is concentrated by evaporation to obtain a second alkaline leaching agent 3, and the second alkaline leaching agent 3 can be mixed with the first product for alkaline leaching treatment.

[0118] The dried first filter residue 1 is used to perform the following processes B1 and B3 respectively; the dried first filter residue is used to perform the following process B2.

[0119] Process B1:

[0120] The dried first filter residue 1 is ground to obtain coarse aluminum ash (solid particles with a particle size less than 100 mesh), the coarse aluminum ash is mixed with a 15% by mass ammonium sulfate solution in a mass ratio of 1:5, and then hydrolyzed at 90° C. for 4 hours to release NH3 and produce a second product, and the released NH3 and the second product are collected respectively;

[0121] Performing a second separation treatment on the second product to obtain a second filtrate 1 and a second filter residue 1;

[0122] The second filter residue 1 is dried at 105° C. to obtain a dry second filter residue 1;

[0123] The second filtrate 1 is added into aqueous ammonia (PH=11) to cause a precipitation reaction to obtain a mixture;

[0124] The mixture is subjected to solid-liquid separation to obtain a precipitate 1;

[0125] The precipitate 1 is washed and then dried at 105° C. to obtain a dried precipitate 1;

[0126] The dried precipitate 1 was subjected to a second calcination treatment at 800° C. for 18 min to obtain magnesium oxide 1.

[0127] In this process B1, the collected NH3 can be used to prepare ammonium sulfate solution.

[0128] Process B2:

[0129] Grind the dried first filter residue 2 to obtain coarse aluminum ash (solid particles with a particle size less than 100 mesh), mix the coarse aluminum ash with a 45% by mass ammonium sulfate solution at a mass ratio of 1:5, and then perform a hydrolysis reaction at 90° C. for 4 hours to release NH3 and produce a second product, and collect the released NH3 and the second product respectively;

[0130] Performing a second separation treatment on the second product to obtain a second filtrate 2 and a second filter residue 2;

[0131] The second filter residue 2 is dried at 105° C. to obtain a dry second filter residue 2;

[0132] The second filtrate 1 is added into aqueous ammonia (PH=11) to cause a precipitation reaction to obtain a mixture;

[0133] The mixture is subjected to solid-liquid separation to obtain a precipitate 2;

[0134] The precipitate 2 is washed and then dried at 105° C. to obtain a dried precipitate 2;

[0135] The dried precipitate 2 was subjected to a second calcination treatment at 800° C. for 18 min to obtain magnesium oxide 2.

[0136] In this process B2, the collected NH3 can be used to prepare ammonium sulfate solution.

[0137] Process B3:

[0138] Grind the dried first filter residue 2 to obtain coarse aluminum ash (solid particles with a particle size less than 100 mesh), mix the coarse aluminum ash with a 45% by mass ammonium sulfate solution at a mass ratio of 1:5, and then perform a hydrolysis reaction at 90° C. for 4 hours to release NH3 and produce a second product, and collect the released NH3 and the second product respectively;

[0139] Performing a second separation treatment on the second product to obtain a second filtrate 3 and a second filter residue 3;

[0140] The second filter residue 3 is dried at 105° C. to obtain a dry second filter residue 3;

[0141] The second filtrate 1 is added into aqueous ammonia (PH=11) to cause a precipitation reaction to obtain a mixture;

[0142] The mixture is subjected to solid-liquid separation to obtain a precipitate 3;

[0143] The precipitate 3 is washed and then dried at 105° C. to obtain a dried precipitate 3;

[0144] The dried precipitate 3 is dissolved in water to prepare a solution, and then CO2 is introduced into the solution to react to obtain micro-nano hydrated magnesium carbonate.

[0145] In this process B3, the collected NH3 can be used to prepare ammonium sulfate solution.

[0146] Comparative Example

[0147] The resource utilization method of the secondary aluminum ash of this comparative example includes:

[0148] Pretreatment: secondary aluminum ash, sodium carbonate and water are mixed in a mass ratio of 100:1:500, reacted at 85°C for 2h, and the reaction product is separated to obtain filter residue; the filter residue is then dried at 105°C to obtain pretreated secondary aluminum ash. The pretreated secondary aluminum ash is then used for process A1.

[0149] Process A1:

[0150] The pretreated secondary aluminum ash is mixed with sodium carbonate, and the molar ratio of sodium carbonate to aluminum oxide in the pretreated secondary aluminum ash is 1.1, and then a first calcination treatment is performed at 1200° C. for 1.5 hours to release CO2 and produce a first product, and the released CO2 and the first product are collected respectively;

[0151] The first product and the first alkaline leaching agent are mixed and then subjected to alkaline leaching treatment at L / S=10 and 85°C for 15 minutes. The first alkaline leaching agent includes 15g / L Na2O K , concentration is 5g / L Na2O C ;

[0152] The mixed material is subjected to a first separation treatment to obtain a first filtrate 4 and a first filter residue 4;

[0153] The first filter residue 4 is dried at 105° C. to obtain a dried first filter residue 4;

[0154] The first filtrate 4 is decomposed and separated according to the Bayer process to obtain a mother liquor 4 and aluminum hydroxide 4; the aluminum hydroxide 4 is calcined at 1000° C. for 1 hour to obtain aluminum oxide 4.

[0155] In the present process A1, the mother liquor 4 is concentrated by evaporation to obtain a second alkaline leaching agent 4, and the second alkaline leaching agent 4 can be used to mix with the first product for alkaline leaching treatment.

[0156] Process B1:

[0157] The dried first filter residue 4 is ground to obtain coarse aluminum ash (solid particles with a particle size less than 100 mesh), the coarse aluminum ash is mixed with a sulfuric acid solution with a mass fraction of 45% in a mass ratio of 1:5, and then hydrolyzed at 90° C. for 4 hours to obtain a second product;

[0158] Performing a second separation treatment on the second product to obtain a second filtrate 4 and a second filter residue 4;

[0159] The second filter residue 4 is dried at 105° C. to obtain a dry second filter residue 4;

[0160] The second filtrate 4 is added to aqueous ammonia (PH=11) to cause a precipitation reaction to obtain a mixture;

[0161] The mixture is subjected to solid-liquid separation to obtain a precipitate 4;

[0162] The precipitate 4 is washed and then dried at 105° C. to obtain a dried precipitate 4;

[0163] The dried precipitate 4 was subjected to a second calcination treatment at 800° C. for 18 min to obtain magnesium oxide 3.

[0164] Performance Characterization

[0165] 1. X-ray diffraction (XRD) diagram:

[0166] Figure 2 is the XRD diagram of the first filter residue 2 in process A2 of Example 1 of the present invention, Figure 3 is the XRD diagram of the second filter residue 2 in process B2 of Example 1 of the present invention, Figure 4 This is the XRD diagram of the precipitate 2 after drying in process B2 of Example 1 of the present invention.

[0167] like Figure 2 As shown, the components contained in the first filter residue 2 are MgO, BaTiO3, CaSiO3, Al2O3, SiO2, CaTiO3, and Fe.

[0168] like Figure 3 As shown, the components contained in the second filter residue 2 are CaSO4·2H2O, BaSO4, and CaTiO3.

[0169] like Figure 4 As shown, the composition of precipitate 2 is Mg(OH)2, indicating that the precipitate is Mg(OH)2.

[0170] 2. Scanning electron microscope (SEM) image:

[0171] Figure 5 This is a 10,000-fold SEM image of the first filter residue 2 in process A2 of Example 1 of the present invention; Figure 6 This is a 30,000-fold SEM image of the first filter residue 2 in process A2 of Example 1 of the present invention; Figure 7 This is a SEM image of the second filter residue 2 in process B2 of Example 1 of the present invention; Figure 8 This is the EDS element spectrum of the rod-shaped substances on the surface of the second filter residue 2 in process B2 of Example 1 of the present invention; Fig. 9 This is a 50,000-fold SEM image of the precipitate 2 after drying in process B2 of Example 1 of the present invention; Fig.10 This is a 20,000-fold SEM image of the precipitate 2 after drying in process B2 of Example 1 of the present invention.

[0172] like Figure 5-Figure 6As shown, from the SEM images of the first filter residue 2 at 10,000 times and 330,000 times, it can be seen that there are many holes on the surface of the first filter residue 2. This is because the secondary aluminum ash reacts with the alkaline reactant to generate dissolved sodium aluminate, which causes many holes in the first filter residue 2 left after the sodium aluminate is dissolved.

[0173] from Figure 7-Figure 8 It can be seen that the rod-shaped objects on the surface of the second filter residue 2 are CaSO4·2H2O.

[0174] like Figure 9-10 As shown, the SEM image shows that the precipitate 2 is in the shape of a flower ball. Figure 4 It can be concluded that precipitate 2 is Mg(OH)2 in the shape of a flower ball.

[0175] 3. Dissolution rate:

[0176] (1) The calculation method of the dissolution rate of alumina is:

[0177]

[0178] in, Indicates the dissolution rate of aluminum oxide, represents the percentage of alumina in the first product, W CaO represents the percentage of calcium oxide in the first product, It represents the ratio of the percentage of aluminum oxide to the percentage of calcium oxide in the first filter residue. It represents the ratio of the percentage of aluminum oxide to the percentage of calcium oxide in the first product.

[0179] The percentage of calcium oxide in the above-mentioned first product refers to the percentage of calcium ions in the first product, that is, the percentage of calcium ions in the first product is equal to the percentage of calcium oxide in the first product.

[0180] The percentage of calcium oxide in the first filter residue refers to the percentage of calcium ions in the first filter residue, that is, the percentage of calcium ions in the first filter residue is equal to the percentage of calcium oxide in the first filter residue.

[0181] (2) The dissolution rate of magnesium oxide is calculated as follows:

[0182]

[0183] Among them, η MgO Indicates the dissolution rate of magnesium oxide, w 第一滤渣MgO Indicates the mass percentage of magnesium oxide in the first filter residue, w 第二滤渣MgO Indicates the mass percentage of magnesium oxide in the second filter residue.

[0184] According to the above-mentioned calculation method for the dissolution rate of aluminum oxide, the dissolution rates of aluminum oxide in process A1, process A2, and process A3 of Example 1 of the present invention are calculated, and the results are shown in Table 1; according to the above-mentioned calculation method for the dissolution rate of magnesium oxide, the dissolution rates of magnesium oxide in process B1 and process B2 of Example 1 of the present invention are calculated, and the results are shown in Table 2;

[0185] Table 1 Dissolution rate of alumina

[0186] project Dissolution rate of alumina Example 1 Process A1 92.65％ Example 1 Process A2 98.59％ Example 1 Process A3 99.06％ Comparative process A1 98.59％

[0187] Table 2 Dissolution rate of magnesium oxide

[0188] project Dissolution rate of magnesium oxide Example 1 Process B1 51.87％ Example 1 Process B2 90.27％ Comparative process B1 33.08％

[0189] It can be seen from Table 1 and Table 2 that when the molar ratio of sodium carbonate to alumina in the pretreated secondary aluminum ash is 1.1 in Process A2 of Example 1, the dissolution rate of alumina can reach 98.59%, when the molar ratio of sodium carbonate to alumina in the pretreated secondary aluminum ash is 1.4 in Process A3 of Example 1, the dissolution rate of alumina can reach 99.06%, and when the molar ratio of sodium carbonate to alumina in the pretreated secondary aluminum ash is 0.9 in Process A1 of Example 1, the dissolution rate of alumina is 92.65%, which shows that the combination of secondary aluminum ash and sodium carbonate can make the dissolution rate of alumina in secondary aluminum ash reach more than 98%.

[0190] Compared with comparative example process B1, in process B2 of embodiment 1, ammonium sulfate with a mass fraction of 45% is used, so that the dissolution rate of magnesium oxide in the second filter residue 2 can reach 90.27%. At the same time, the materials produced in the process of preparing magnesium oxide can be recycled, which greatly reduces the production cost.

[0191] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for comprehensive resource utilization of secondary aluminum ash, characterized in that: include: The secondary aluminum ash and the alkaline reactant are mixed and then subjected to a first calcination treatment, and a first product and CO2 are collected; performing an alkaline leaching treatment and a first separation treatment on the first product in sequence, and collecting a first filtrate and a first filter residue; The first filtrate is used to prepare aluminum oxide; The first filter residue is mixed with the first ammonium salt solution to perform a hydrolysis reaction, and a second product and NH3 are collected; Performing a second separation treatment on the second product to collect a second filtrate and a second filter residue; The NH3 is added with water to prepare ammonia water, and then added to the second filtrate for reaction, and the product after the reaction is subjected to a third separation treatment to collect a second ammonium salt solution and magnesium hydroxide; The second ammonium salt solution is used to mix with the first filter residue to perform a hydrolysis reaction; The magnesium hydroxide is used to prepare magnesium oxide, and / or the magnesium hydroxide is dissolved in water and then introduced into the CO2 to prepare micro-nano hydrated magnesium carbonate.

2. The method for comprehensive resource utilization of secondary aluminum ash according to claim 1, characterized in that: Calculated by molar ratio, the molar ratio of the alkaline reactant to the alumina in the secondary aluminum ash is 0.1-4.

3. The method for comprehensive resource utilization of secondary aluminum ash according to claim 1 or 2, characterized in that: Calculated by molar ratio, the molar ratio of the alkaline reactant to the alumina in the secondary aluminum ash is 1.1 to 1.

4.

4. The method for comprehensive resource utilization of secondary aluminum ash according to any one of claims 1 to 3, characterized in that: The alkaline reactant is at least one of sodium carbonate, sodium hydroxide and sodium bicarbonate.

5. The method for comprehensive resource utilization of secondary aluminum ash according to claim 1, characterized in that: The temperature of the first calcination treatment is 500°C to 1450°C and the time is 0.2h to 2h; And / or, the hydrolysis reaction is carried out at a temperature of 20°C to 100°C and for a time of 0.5h to 10h.

6. The method for comprehensive resource utilization of secondary aluminum ash according to claim 1, characterized in that: In the first ammonium salt solution, the mass ratio of ammonium salt to water is 5% to 70%.

7. The method for comprehensive resource utilization of secondary aluminum ash according to claim 1, characterized in that: The step of using magnesium hydroxide to prepare magnesium oxide is: The magnesium hydroxide is subjected to a second calcination treatment to obtain magnesium oxide.

8. The method for comprehensive resource utilization of secondary aluminum ash according to claim 6, characterized in that: The second calcination treatment is performed at a temperature of 500° C. to 900° C. and for a time of 1 min to 30 min.

9. The method for comprehensive resource utilization of secondary aluminum ash according to claim 1, characterized in that: Before the first calcination treatment, the method further includes pre-treating the secondary aluminum ash. The pretreatment comprises: mixing secondary aluminum ash, a sodium source and water and reacting them to obtain a reaction product, performing a fourth separation treatment on the reaction product, and the filter residue obtained by separation is the secondary aluminum ash after the pretreatment.

10. The method for comprehensive resource utilization of secondary aluminum ash according to claim 9, characterized in that: Calculated by mass ratio, the mass ratio of the secondary aluminum ash, the sodium source and water is (50-150): (0.2-2): (150-750).

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