A method for recovering aluminum and fluorine from electrolytic aluminum solid waste

Abstract

The application provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, which comprises the following steps: mixing electrolytic aluminum solid waste with an alkali solution to perform slurry leaching, and obtaining leaching liquid and leaching residue after liquid-solid separation; adding seeds to the leaching liquid to perform aging, and obtaining aluminum hydroxide and aging liquid after liquid-solid separation; performing secondary leaching on the leaching residue, and obtaining secondary leaching liquid and secondary leaching residue after liquid-solid separation; adding an additive to the secondary leaching liquid to perform reaction, and obtaining sodium fluoride and mother liquor after liquid-solid separation; performing regeneration treatment on the mother liquor to obtain the additive and treated mother liquor, wherein the additive is used for extracting sodium fluoride, and the treated mother liquor is used for secondary leaching. The method can realize the recovery of aluminum and fluorine resources in electrolytic aluminum solid waste, the extraction rate of aluminum and fluorine is high through two-step leaching, the purity of aluminum and fluorine products converted by the leaching liquid is high, the leaching agent and the product conversion additive can be regenerated and recycled, the process is clean and pollution-free, and the method has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of chemical metallurgy, and relates to a method for recovering aluminum and fluorine from electrolytic aluminum solid waste. BACKGROUND

[0002] China is a big country of aluminum industry. In 2022, the production of electrolytic aluminum in China was about 40 million tons, ranking first in the world. The cathode of the electrolytic aluminum tank in the electrolytic aluminum industry is gradually pulverized due to the erosion of the electrolyte. The electrolytic aluminum tank must be overhauled, cleaned and replaced every 3-5 years. The waste slag containing cathode carbon blocks, refractory insulation materials and electrolyte is replaced. More than 2 million tons of electrolytic aluminum solid waste is generated in the electrolytic aluminum industry in China every year. The electrolytic aluminum solid waste has great harm to the environment, and part of the soluble fluorine and cyanide causes serious pollution to the soil and groundwater. In the National Hazardous Waste List, the overhaul slag and carbon slag are listed as hazardous waste. The traditional treatment method of electrolytic aluminum solid waste in China is landfill, which not only needs to occupy a large amount of land, has long-term pollution hidden dangers, but also causes waste of resources such as carbon, lithium, fluorine and aluminum.

[0003] At present, there are many methods for extracting and recycling lithium resources and carbon resources from electrolytic aluminum solid waste, and some methods have realized industrial application. In order to realize the sustainable development and resource recycling of the electrolytic aluminum industry in China, more and more attention is paid to the recovery of aluminum and fluorine resources with high content in electrolytic aluminum solid waste.

[0004] For the recovery of aluminum and fluorine resources in electrolytic aluminum solid waste, CN115676861A discloses a method for preparing nepheline and sodium metaaluminate from overhaul slag. The method first calcines the overhaul slag with sodium oxide, then roasts the clinker and adds water to leach to obtain nepheline, and the filtrate is passed into carbon dioxide tail gas to obtain aluminum hydroxide precipitate, and magnesium fluoride is recovered in the solution. CN106064813A discloses a comprehensive recovery method for waste cathode carbon blocks of aluminum electrolysis tank. First, the carbon blocks are decyanated by roasting, then the carbon slag is separated by flotation, and finally the electrolyte slag is roasting and alkali leaching, and the mixture of cryolite and aluminum hydroxide is recovered by passing carbon dioxide. CN114074949A discloses a method for catalytic dissociation of fluorides in electrolytic tank waste. The electrolytic tank waste is crushed, calcined with carbonate, water leached, reacted with magnesium chloride, and then filtered and dried to obtain magnesium chloride product. CN114314625A discloses a method for recovering fluorinated salt from complex aluminum electrolyte. The aluminum electrolyte is prepared into aluminum fluoride, sodium fluoride or cryolite by aluminum sulfate roasting, acid washing, lithium removal and other processes, and aluminum hydroxide is obtained by reacting the alkali leaching solution with acid. At present, there are still problems such as large amount of reagent, long process flow, high cost and the like in the method for recovering aluminum and fluorine resources from electrolytic aluminum solid waste.

[0005] In summary, it is urgent to develop a new method for recovering aluminum and fluorine from electrolytic aluminum solid waste with short process flow, low cost, renewable circulation of reagents and clean process, so as to realize efficient extraction and recovery of fluorine and aluminum. SUMMARY

[0006] In order to solve the problems in the prior art, the present application aims to provide a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, which can realize the recovery of aluminum and fluorine resources in the electrolytic aluminum solid waste, has high extraction rate of aluminum and fluorine in two-step leaching, high purity of aluminum and fluorine products converted from the leaching solution, and can recycle the leaching agent and product conversion additives, and has a wide application prospect.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] The present application provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, characterized in that the method comprises the following steps:

[0009] (1) mixing electrolytic aluminum solid waste with an alkali solution for slurry leaching, and separating the liquid and solid to obtain a leaching solution and a leaching residue;

[0010] (2) adding seeds to the leaching solution of step (1) for aging, and separating the liquid and solid to obtain aluminum hydroxide and an aging solution;

[0011] (3) performing secondary leaching on the leaching residue of step (1), and separating the liquid and solid to obtain a secondary leaching solution and a secondary leaching residue;

[0012] (4) adding an additive to the secondary leaching solution of step (3) for reaction, and separating the liquid and solid to obtain sodium fluoride and a mother liquor;

[0013] (5) performing regeneration treatment on the mother liquor of step (4) to obtain an additive and a treated mother liquor, wherein the additive is recycled to step (4), and the treated mother liquor is recycled to step (3) for secondary leaching.

[0014] As a preferred technical solution of the present application, the alkali solution of step (1) comprises a sodium hydroxide aqueous solution.

[0015] Preferably, the mass-to-volume ratio of the electrolytic aluminum solid waste to the alkali solution is 1:(0.5-6), such as 1:0.5, 1:0.75, 1:1, 1:1.2, 1:1.5, 1:2, 1:2.25, 1:2.5, 1:2.97, 1:3, 1:3.5, 1:4, 1:4.12, 1:4.5, 1:4.75, 1:5 or 1:6, but is not limited to the listed values, and other values not listed in this range are also applicable, and the ratio is preferably 1:(1-3).

[0016] Preferably, the molar ratio of aluminum to sodium hydroxide in the slurry of step (1) is 1 : (4-8), such as 1 :4, 1 :4.25, 1 :4.5, 1 :5, 1 :5.5, 1 :5.75, 1 :6, 1 :6.5, 1 :7, 1 :7.5, or 1 :8, but is not limited to the listed values, and other values not listed within the range are also applicable.

[0017] As a preferred technical solution of the present application, the temperature of the slurry leaching of step (1) is 60-250°C, such as 60°C, 70°C, 80°C, 90°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 215°C, 230°C, 245°C, or 250°C, preferably 80-200°C, and more preferably 100-150°C; and the time is 0.5-5h, such as 0.5h, 0.75h, 1h, 1.5h, 1.75h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, or 5h, but is not limited to the listed values, and other values not listed within the range are also applicable.

[0018] As a preferred technical solution of the present application, the aging of step (2) includes first aging by adding first seeds to the leaching solution of step (1), and second aging by adding second seeds.

[0019] As a preferred technical solution of the present application, the first seeds are aluminum hydroxide with an average particle size D50 = 30-50μm, such as 30μm, 32μm, 35μm, 37.5μm, 40μm, 45μm, 48μm, or 50μm, but is not limited to the listed values, and other values not listed within the range are also applicable.

[0020] Preferably, the volume fraction of aluminum hydroxide particles with a particle size < 15μm in the first seeds is 5-20%, such as 5%, 6%, 8%, 10%, 11.5%, 12%, 15%, 16%, 17%, 19%, and 20%, but is not limited to the listed values, and other values not listed within the range are also applicable.

[0021] As a preferred technical solution of the present application, the volume-to-mass ratio of the leaching solution to the first seeds is 1 : (0.3-0.6), such as 1 :0.3, 1 :0.31, 1 :0.35, 1 :0.37, 1 :0.4, 1 :0.42, 1 :0.45, 1 :0.475, 1 :0.5, 1 :0.52, 1 :0.55, 1 :0.58, 1 :0.59, or 1 :0.6, but is not limited to the listed values, and other values not listed within the range are also applicable.

[0022] Preferably, the first aging temperature is 60-100℃, such as 60℃, 62.5℃, 65℃, 67.5℃, 70℃, 72.5℃, 75℃, 80℃, 83℃, 85℃, 90℃, 95℃, 97.5℃ or 100℃, etc.; and the time is 1-5h, such as 1h, 1.25h, 1.5h, 1.75h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, etc., but not only limited to the listed values, other values not listed in the above ranges are also applicable.

[0023] As a preferred technical solution of the present application, the second seed crystal is aluminum hydroxide with an average particle size D50 = 15-25μm, such as 15μm, 16μm, 17.5μm, 19μm, 20μm, 22μm, 24μm or 25μm, etc., but not only limited to the listed values, other values not listed in the above ranges are also applicable.

[0024] Preferably, the volume fraction of aluminum hydroxide particles with a particle size <15μm in the second seed crystal is 30-50%, such as 30%, 32.5%, 33%, 35%, 37.5%, 40%, 42.5%, 45%, 46%, 49% and 50%, etc., but not only limited to the listed values, other values not listed in the above ranges are also applicable.

[0025] As a preferred technical solution of the present application, the volume-to-mass ratio of the leaching solution to the second seed crystal is 1:(0.3-0.6), such as 1:0.3, 1:0.31, 1:0.35, 1:0.37, 1:0.4, 1:0.42, 1:0.45, 1:0.475, 1:0.5, 1:0.52, 1:0.55, 1:0.58, 1:0.59 or 1:0.6, etc., but not only limited to the listed values, other values not listed in the above ranges are also applicable.

[0026] Preferably, the second aging temperature is 30-50℃, such as 30℃, 32.5℃, 33℃, 35℃, 37.5℃, 39℃, 40℃, 42.5℃, 43℃, 45℃, 47.5℃ or 50℃, etc.; and the time is 1-5h, such as 1h, 1.25h, 1.5h, 1.75h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, etc., but not only limited to the listed values, other values not listed in the above ranges are also applicable.

[0027] As a preferred technical scheme of the present application, the solid-liquid mass volume ratio of the secondary leaching in step (3) is 1:(10-25), such as 1:10, 1:12, 1:12.5, 1:13, 1:15, 1:17.5, 1:20, 1:22.5, 1:23 or 1:25, etc., but not limited to the listed values, and other values not listed in the range are also applicable.

[0028] Preferably, the temperature of the secondary leaching in step (3) is 20-100℃, such as 20℃, 30℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃, etc.; and the time is 0.5-5h, such as 0.5h, 1h, 1.25h, 1.5h, 1.75h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, etc., but not limited to the listed values, and other values not listed in the range are also applicable.

[0029] As a preferred technical scheme of the present application, the additive in step (4) includes any one or a combination of at least two of methanol, ethanol, isopropanol and ammonia, and typical but non-limiting examples of the combination include: a combination of methanol and ethanol, a combination of methanol and isopropanol, a combination of methanol, ethanol and isopropanol, a combination of methanol, ethanol, isopropanol and ammonia, etc.

[0030] Preferably, the volume ratio of the secondary leaching liquid to the additive in step (4) is 1:(0.3-3), such as 1:0.3, 1:0.5, 1:0.75, 1:1, 1:1.25, 1:1.5, 1:2, 1:2.5, 1:2.75 or 1:3, etc., but not limited to the listed values, and other values not listed in the range are also applicable.

[0031] Preferably, the reaction temperature in step (4) is 25-45℃, such as 25℃, 27.5℃, 30℃, 32.5℃, 35℃, 37.5℃, 40℃, 42.5℃, 43℃ or 45℃, etc.; and the time is 0.25-2h, such as 0.25h, 0.3h, 0.5h, 0.75h, 1h, 1.2h, 1.25h, 1.3h, 1.5h, 1.75h or 2h, etc., but not limited to the listed values, and other values not listed in the range are also applicable.

[0032] Compared with the prior art, the present application has at least the following beneficial effects:

[0033] The application provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, in which the aluminum electrolytic solid waste is subjected to water-based sodium hydroxide leaching to obtain a sodium aluminate leaching solution and a sodium fluoride leaching solution, respectively, the leaching solution is subjected to seed aging and additive reaction to convert into aluminum hydroxide and sodium fluoride products, respectively, and the aging solution is recycled for slurry leaching, and the sodium fluoride mother liquor is recycled for secondary water leaching. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a process flow diagram of the method for recovering aluminum and fluorine from electrolytic aluminum solid waste provided in the specific embodiment of the application.

[0035] The application will be further described in detail below. However, the examples described below are only simple examples of the application and do not represent or limit the protection scope of the application, and the protection scope of the application is subject to the claims. DETAILED DESCRIPTION

[0036] The technical solutions of the application will be further described below in combination with the drawings and through specific embodiments.

[0037] The specific embodiment of the application provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, which comprises the following steps:

[0038] (1) mixing electrolytic aluminum solid waste with an alkali solution for slurry leaching, and obtaining leaching solution and leaching residue after liquid-solid separation;

[0039] (2) adding seeds to the leaching solution in step (1) for aging, and obtaining aluminum hydroxide and aging solution after liquid-solid separation;

[0040] (3) performing secondary leaching on the leaching residue in step (1), and obtaining secondary leaching solution and secondary leaching residue after liquid-solid separation;

[0041] (4) adding an additive to the secondary leaching solution in step (3) for reaction, and obtaining sodium fluoride and mother liquor after liquid-solid separation;

[0042] (5) performing regeneration treatment on the mother liquor in step (4) to obtain an additive and treated mother liquor, and recycling the additive to step (4) and recycling the treated mother liquor to step (3) for secondary leaching.

[0043] In the present application, first, the aluminum electrolysis solid waste is slurried and leached with sodium hydroxide aqueous solution. Under the action of strong alkali, the components such as cryolite and aluminum oxide in the electrolytic aluminum solid waste are decomposed and converted into easily soluble sodium aluminate leaching solution and insoluble sodium fluoride leaching residue. Secondly, the sodium aluminate leaching solution is subjected to aging reaction to obtain aluminum hydroxide product, and the aging liquid is recycled for slurry leaching, and the leaching residue is subjected to secondary water leaching to obtain sodium fluoride aqueous solution. Then, the sodium fluoride aqueous solution is added with an additive to precipitate sodium fluoride. Finally, the additive is recovered from the sodium fluoride precipitation mother liquor to realize regeneration and recycling of the additive, and the mother liquor is recycled for secondary water leaching. The method can realize recovery of aluminum and fluorine resources in electrolytic aluminum solid waste, the extraction rate of aluminum and fluorine is high in two-step leaching, the leaching solution is converted into aluminum and fluorine products with high purity, the leaching agent and product conversion additive can be regenerated and recycled, the process is clean and pollution-free, and has a broad application prospect.

[0044] In one specific embodiment of the present application, before the slurry leaching in step (1), the electrolytic aluminum solid waste is first crushed and finely ground to obtain electrolytic aluminum solid waste powder.

[0045] In one specific embodiment of the present application, the particle size of the electrolytic aluminum solid waste powder is not greater than 150 μm, for example, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 140 μm or 150 μm, etc., but not limited to the listed values, and other values not listed in the range are also applicable.

[0046] In one specific embodiment of the present application, the electrolytic aluminum solid waste includes one or a combination of at least two of aluminum electrolyte, overhaul slag and carbon residue, and typical but non-limiting examples of the combination include: a combination of aluminum electrolyte and overhaul slag, a combination of overhaul slag and carbon residue, a combination of aluminum electrolyte and carbon residue, a combination of aluminum electrolyte, overhaul slag and carbon residue, etc.

[0047] In the present application, the electrolytic aluminum solid waste can be aluminum electrolyte, overhaul slag and carbon residue removed from the electrolytic cell, or tail residue after harmless treatment or extraction of lithium, carbon and other resources from the electrolytic aluminum solid waste.

[0048] In one specific embodiment of the present application, when the electrolytic aluminum solid waste contains overhaul slag and / or carbon residue raw materials, a chemical oxidation cyanide-destroying agent is added in the regeneration reaction process of step (3).

[0049] The cyanide-destroying agent is one or a combination of at least two of peroxide, hypochlorous acid and its salt, perchloric acid and its salt, persulfuric acid and its salt, oxygen, ozone and chlorine, and the combination is typically but not limited to: a combination of peroxide and ozone, a combination of hypochlorous acid and its salt and persulfuric acid and its salt, a combination of hypochlorous acid and its salt, perchloric acid and its salt and persulfuric acid and its salt, a combination of peroxide, perchloric acid and its salt, persulfuric acid and its salt and chlorine, a combination of hypochlorous acid and its salt, perchloric acid and its salt, persulfuric acid and its salt, oxygen and ozone, a combination of hypochlorous acid and its salt, perchloric acid and its salt, persulfuric acid and its salt, oxygen, ozone and chlorine, a combination of peroxide, hypochlorous acid and its salt, perchloric acid and its salt, persulfuric acid and its salt, oxygen, ozone and chlorine, and the like.

[0050] In the present application, when the electrolytic aluminum solid waste contains overhaul slag and / or carbon slag raw materials, the addition of the chemical oxidizing cyanide-destroying agent in the regeneration reaction process can effectively decompose cyanide in the leaching solution.

[0051] In the present application, under the synergistic effect of suitable solid-liquid mass / volume ratio, molar ratio of aluminum to sodium hydroxide in the slurry, leaching temperature and leaching time, etc., the cryolite and aluminum oxide in the electrolytic aluminum solid waste are decomposed into sodium aluminate and sodium fluoride, and the difference in physicochemical properties of sodium fluoride and sodium aluminate under the conditions of the alkali liquor system in the present application is utilized to realize the entry of sodium aluminate into the leaching solution, while sodium fluoride remains in the leaching residue.

[0052] In one specific embodiment of the present application, the aging solution in step (2) is used for preparing the alkali solution in step (1). The main reason is that the hydrolysis of sodium aluminate produces sodium hydroxide, and only a small amount of sodium hydroxide needs to be supplemented in the aging solution for the leaching of electrolytic aluminum solid waste, thereby reducing the use of leaching agents.

[0053] In the present application, the aging process is divided into two times of adding the aluminum hydroxide seed obtained by aging screening, the average particle size of the seed added for the first time is large, less than 15 microns, the average particle size of the seed added for the second time is small, more than 15 microns, the aging efficiency is strengthened under the action of certain temperature and time for two times, the yield of aluminum hydroxide is high, and the product purity is high. In the present application, the sodium aluminate solution has high supersaturation, when the seed is added for the first time, due to high temperature aging and large seed particle size, the burst crystallization of aluminum hydroxide is avoided, the crystal formation speed is moderate, the aluminum hydroxide crystallization is complete, the aluminum hydroxide has less impurities and high purity; but with the decrease of supersaturation, the crystallization speed of aluminum hydroxide is slowly reduced, at this time, the seed is added for the second time, due to the use of low temperature aging and the appropriate reduction of seed particle size and the increase of the distribution ratio of small particle size seed, the sodium aluminate supersaturation is increased, the crystallization speed is accelerated, but the burst crystallization will not occur, which is beneficial to the growth of small size seed and the formation of complete aluminum hydroxide crystallization, and the impurities are still not carried, the high-purity aluminum hydroxide is prepared, and due to the improvement of the crystallization speed, the aging efficiency and the yield of aluminum hydroxide are also improved.

[0054] In one specific embodiment of the present application, the leaching agent used in the secondary leaching of step (3) is the mother liquor after the treatment of step (5).

[0055] In the present application, the differences between sodium fluoride and the residual carbon and silicon physicochemical components of solid waste of electrolytic aluminum are utilized, the alkali leaching residue is subjected to secondary leaching with water, the leaching of silicon components is avoided, and the leaching efficiency of fluorine ions is improved.

[0056] In the present application, the differences in the solubility and crystallization performance of secondary leaching sodium fluoride in the mixture of water and additives are researched and utilized, the crystallization reaction of sodium fluoride is carried out under the synergistic action of certain reagent ratio, reaction temperature and reaction time, and the sodium fluoride product with high recovery rate and purity is obtained.

[0057] In one specific embodiment of the present application, the regeneration treatment of the mother liquor in step (5) is that the mother liquor is cooled and recovered after rectification or distillation.

[0058] In one specific embodiment of the present application, the rectification or distillation temperature is 80-95℃, for example, 80℃, 80.5℃, 82.5℃, 85℃, 87℃, 88℃, 90℃, 91.5℃, 92.5℃ or 95℃, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0059] In one specific embodiment of the present application, the regeneration treatment is ended when the recovery rate of the additive reaches 90%.

[0060] In the present application, the differences in solubility and azeotropic point of the sodium fluoride crystallization mother liquor and the additive in the system after crystallization are studied, and the additive is recovered by precise temperature control rectification or distillation, so as to realize the regeneration of the additive and reuse it in the sodium fluoride solution crystallization reaction, and the solution after recovering the additive is reused for secondary leaching.

[0061] In one specific embodiment of the present application, the leaching residue, secondary leaching residue, aluminum hydroxide and sodium fluoride and the like solids include washing with pure water, and the washing liquid is combined with the filtrate, and the aluminum hydroxide and sodium fluoride further include drying treatment.

[0062] In one specific embodiment of the present application, the process for recovering aluminum and fluorine from electrolytic aluminum solid waste includes the following steps: Figure 1

[0063] (1) The electrolytic aluminum solid waste with a particle size of not more than 150 μm after crushing and grinding is slurried with a sodium hydroxide aqueous solution at a solid-liquid mass / volume ratio of 1:(0.5-6), the molar ratio of aluminum to sodium hydroxide in the slurry is 1:(4-8), and the leaching is carried out at 60-250℃ for 0.5-5h, and then liquid-solid separation is performed to obtain a leaching solution and a leaching residue;

[0064] (2) Seed crystals are added twice to the leaching solution of step (1) for aging, the first time, the seed crystal aluminum hydroxide has an average particle size D50 of 30-50 μm, the volume ratio of seed crystal aluminum hydroxide with a particle size of less than 15 μm is 5-20%, the liquid-solid volume / mass ratio of the leaching solution to the seed crystal aluminum hydroxide is 1:(0.3-0.6), and the aging is carried out at 60-100℃ for 1-5h, the second time, the seed crystal aluminum hydroxide has an average particle size D50 of 15-25 μm, the volume ratio of seed crystal aluminum hydroxide with a particle size of less than 15 μm is 30-50%, the liquid-solid volume / mass ratio of the leaching solution to the seed crystal aluminum hydroxide is 1:(0.3-0.6), and the aging is carried out at 30-50℃ for 1-5h, and then liquid-solid separation is performed to obtain aluminum hydroxide and an aging solution; the aging solution is reused for preparing the sodium hydroxide solution in step (1);

[0065] (3) The leaching residue of step (1) is added to the mother liquor after step (5) treatment, and then secondary leaching is carried out at a solid-liquid mass / volume ratio of 1:(10-25), a leaching temperature of 20-100℃ and a leaching time of 0.5-5h, and then liquid-solid separation is performed to obtain a secondary leaching solution and a secondary leaching residue;

[0066] (4) An additive is added to the secondary leaching solution of step (3) at a volume ratio of 1:(0.3-3) and reacted at 25-45℃ for 0.25-2h, and then liquid-solid separation is performed to obtain sodium fluoride and a mother liquor; the additive is any one or a combination of at least two of methanol, ethanol, isopropyl alcohol and ammonia;

[0067] ​(5) The sodium fluoride mother liquor of step (4) is subjected to rectification or distillation at 80-95℃ and then cooled to recover the additive, and the regeneration treatment is ended when the recovery rate of the additive reaches 90%, to obtain the additive and the treated mother liquor, the additive is recycled to step (4), and the treated mother liquor is recycled to step (3).

[0068] In order to better illustrate the present application and facilitate the understanding of the technical solutions of the present application, the typical but non-limiting embodiments of the present application are as follows:

[0069] Embodiment 1:

[0070] The present embodiment provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, which is an aluminum electrolyte, and the main components and contents thereof are as follows: Al 26.23wt%, F 25.84wt%, Na 13.16wt%, K 1.58wt%, Ca 2.86wt%, Mg 0.27wt%, Si 0.13wt%, and C 0.17wt%.

[0071] The process flow chart of the method is shown in Figure 1 The method comprises the following steps:

[0072] (1) The electrolytic aluminum solid waste with a particle size of not more than 118μm after crushing and grinding is slurried with a sodium hydroxide aqueous solution at a solid-liquid mass / volume ratio of 1:5, and leaching is carried out at 120℃ for 3h according to a molar ratio of aluminum to sodium hydroxide in the slurry of 1:6, and then liquid-solid separation is performed to obtain a leaching solution and a leaching residue;

[0073] (2) Seed crystals are added to the leaching solution of step (1) twice, the first time, the average particle size D50 of the seed crystal aluminum hydroxide is 35μm, the volume ratio of the seed crystal aluminum hydroxide with a particle size of less than 15μm is 12%, the liquid-solid volume / mass ratio of the leaching solution to the seed crystal aluminum hydroxide is 1:0.5, and aging is carried out at 80℃ for 3h, the second time, the average particle size D50 of the seed crystal aluminum hydroxide is 15μm, the volume ratio of the seed crystal aluminum hydroxide with a particle size of less than 15μm is 40%, the liquid-solid volume / mass ratio of the leaching solution to the seed crystal aluminum hydroxide is 1:0.4, and aging is carried out at 40℃ for 2h, and then liquid-solid separation is performed to obtain aluminum hydroxide and an aging solution, and the aging solution is recycled to prepare the sodium hydroxide solution in step (1);

[0074] (3) The leaching residue of step (1) is added to the treated mother liquor of step (5) for secondary leaching according to a solid-liquid mass / volume ratio of 1:15, a leaching temperature of 35℃, and a leaching time of 4h, and then liquid-solid separation is performed to obtain a secondary leaching solution and a secondary leaching residue;

[0075] (4) The secondary leaching solution of step (3) is added with an additive (methanol and ethanol at a mass ratio of 1:2) at a volume ratio of 1:2.2 at 30℃ for 0.5h, and then liquid-solid separation is performed to obtain sodium fluoride and a mother liquor;

[0076] (5) The sodium fluoride mother liquor from step (4) is subjected to a recovery additive regeneration treatment after being cooled by 90℃ rectification or distillation. When the recovery rate of the additive reaches 90%, the regeneration treatment ends, obtaining the additive and the treated mother liquor. The additive is recycled to step (4), and the treated mother liquor is recycled to step (3).

[0077] Example 2:

[0078] The present embodiment provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, which is an aluminum electrolyte, and the main components and contents are the same as those in Example 1.

[0079] The method comprises the following steps:

[0080] (1) After being crushed and finely ground, the electrolytic aluminum solid waste with a particle size of not more than 118μm is slurried with a sodium hydroxide aqueous solution at a solid-liquid mass volume ratio of 1:6. The slurry is leached at 60℃ for 5h according to a molar ratio of aluminum to sodium hydroxide of 1:4, and then liquid-solid separation is performed, obtaining a leaching solution and a leaching residue;

[0081] (2) Seed crystals are added to the leaching solution from step (1) twice. The first time, seed crystals of aluminum hydroxide with an average particle size D50 = 40μm are added, and the volume ratio of seed crystals of aluminum hydroxide with a particle size <15μm is 5%. The liquid-solid volume mass ratio of the leaching solution to the seed crystals of aluminum hydroxide is 1:0.3, and the aging is performed at 100℃ for 5h. The second time, seed crystals of aluminum hydroxide with an average particle size D50 = 25μm are added, and the volume ratio of seed crystals of aluminum hydroxide with a particle size <15μm is 50%. The liquid-solid volume mass ratio of the leaching solution to the seed crystals of aluminum hydroxide is 1:0.6, and the aging is performed at 50℃ for 1h. Liquid-solid separation is performed, obtaining aluminum hydroxide and an aging solution, and the aging solution is recycled to prepare the sodium hydroxide solution in step (1);

[0082] (3) The leaching residue from step (1) is added to the treated mother liquor from step (5) according to a solid-liquid mass volume ratio of 1:10, and the secondary leaching is performed at a leaching temperature of 100℃ for 5h. Liquid-solid separation is performed, obtaining a secondary leaching solution and a secondary leaching residue;

[0083] (4) Methanol additive is added to the secondary leaching solution from step (3) according to a volume ratio of 1:0.3, and the reaction is performed at 25℃ for 0.25h. Liquid-solid separation is performed, obtaining sodium fluoride and a mother liquor;

[0084] (5) The sodium fluoride mother liquor from step (4) is subjected to a recovery additive regeneration treatment after being cooled by 80℃ rectification or distillation. When the recovery rate of the additive reaches 90%, the regeneration treatment ends, obtaining the additive and the treated mother liquor. The additive is recycled to step (4), and the treated mother liquor is recycled to step (3).

[0085] Example 3:

[0086] The embodiment provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, the electrolytic aluminum solid waste being aluminum electrolyte, the main components and contents of which are the same as those in the embodiment 1.

[0087] The method comprises the following steps:

[0088] (1) electrolytic aluminum solid waste with a particle size of not more than 118 μm after crushing and grinding is slurried with a sodium hydroxide aqueous solution at a solid-liquid mass / volume ratio of 1:0.5, leaching is performed at 250 DEG C for 0.5 h according to a molar ratio of aluminum to sodium hydroxide in the slurry of 1:8, and then liquid-solid separation is performed to obtain a leaching solution and a leaching residue;

[0089] (2) seed crystals are added to the leaching solution in step (1) twice, the first time, aluminum hydroxide seed crystals with an average particle size D50 = 50 μm and a particle size < 15 μm accounting for 20% in volume are added, the liquid-solid volume / mass ratio of the leaching solution to the aluminum hydroxide seed crystals is 1:0.6, and aging is performed at 80 DEG C for 1 h, the second time, aluminum hydroxide seed crystals with an average particle size D50 = 20 μm and a particle size < 15 μm accounting for 30% in volume are added, the liquid-solid volume / mass ratio of the leaching solution to the aluminum hydroxide seed crystals is 1:0.3, and aging is performed at 40 DEG C for 5 h, then liquid-solid separation is performed to obtain aluminum hydroxide and an aging solution, and the aging solution is reused in step (1) to prepare a sodium hydroxide solution;

[0090] (3) the leaching residue in step (1) is added to the mother liquor after treatment in step (5) to perform secondary leaching at a solid-liquid mass / volume ratio of 1:20, a leaching temperature of 20 DEG C and a leaching time of 0.5 h, and then liquid-solid separation is performed to obtain a secondary leaching solution and a secondary leaching residue;

[0091] (4) ethanol additives are added to the secondary leaching solution in step (3) according to a volume ratio of 1:1 to perform reaction at 35 DEG C for 2 h, and then liquid-solid separation is performed to obtain sodium fluoride and a mother liquor;

[0092] (5) the mother liquor of sodium fluoride in step (4) is subjected to regeneration treatment of recovered additives after rectification or distillation at 95 DEG C and cooling, the regeneration treatment is ended when the recovery rate of the additives reaches 90%, and then the additives and the treated mother liquor are obtained, the additives are reused in step (4), and the treated mother liquor is reused in step (3).

[0093] Embodiment 4:

[0094] The embodiment provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, the electrolytic aluminum solid waste being a large repair slag, the main components and contents of which are as follows: Al 14.72 wt%, F 9.58 wt%, Na 11.01 wt%, K 1.04 wt%, Ca 4.03 wt%, Mg 0.25 wt%, Si 8.24 wt%, and C 11.32 wt%.

[0095] The method comprises the following steps:

[0096] (1) The electrolytic aluminum solid waste with a particle size of not more than 150 μm after crushing and grinding is slurried with a sodium hydroxide aqueous solution at a solid-liquid mass / volume ratio of 1:2, potassium perchlorate and ammonium perchlorate cyanide breakers are added during the slurry process, and the slurry is leached at 80℃ for 4 h according to a molar ratio of aluminum to sodium hydroxide of 1:6, and then liquid-solid separation is performed to obtain a leaching solution and a leaching residue;

[0097] (2) Seed crystals are added to the leaching solution of step (1) twice for aging, the first time, seed crystal aluminum hydroxide with an average particle size D50 of 45 μm is added, the volume ratio of seed crystal aluminum hydroxide with a particle size of less than 15 μm is 15%, the liquid-solid volume mass ratio of the leaching solution to the seed crystal aluminum hydroxide is 1:0.45, and the aging is performed at 70℃ for 3 h, the second time, seed crystal aluminum hydroxide with an average particle size D50 of 17 μm is added, the volume ratio of seed crystal aluminum hydroxide with a particle size of less than 15 μm is 45%, the liquid-solid volume mass ratio of the leaching solution to the seed crystal aluminum hydroxide is 1:0.54, and the aging is performed at 35℃ for 3 h, and then liquid-solid separation is performed to obtain aluminum hydroxide and an aging solution, and the aging solution is recycled to prepare the sodium hydroxide solution in step (1);

[0098] (3) The leaching residue of step (1) is added to the mother liquor after treatment in step (5) for secondary leaching at a solid-liquid mass / volume ratio of 1:25, a leaching temperature of 30℃, and a leaching time of 3 h, and then liquid-solid separation is performed to obtain a secondary leaching solution and a secondary leaching residue;

[0099] (4) Isopropyl alcohol additives are added to the secondary leaching solution of step (3) at a volume ratio of 1:2 for reaction at 32℃ for 1 h, and then liquid-solid separation is performed to obtain sodium fluoride and a mother liquor;

[0100] (5) The mother liquor of sodium fluoride in step (4) is subjected to regeneration treatment of the recovered additives after rectification or distillation at 90℃ and cooling, the regeneration treatment is ended when the recovery rate of the additives reaches 90%, and then the additives and the treated mother liquor are obtained, the additives are recycled to step (4), and the treated mother liquor is recycled to step (3).

[0101] Example 5:

[0102] The present embodiment provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, the electrolytic aluminum solid waste is overhaul residue, and the main components and contents thereof are the same as those in example 4.

[0103] The method comprises the following steps:

[0104] (1) The electrolytic aluminum solid waste with a particle size of not more than 150 μm after crushing and grinding is slurried with a sodium hydroxide aqueous solution at a solid-liquid mass / volume ratio of 1:2.5, calcium peroxide cyanide breaker is added during the slurry process, and the slurry is leached at 100℃ for 3.5 h according to a molar ratio of aluminum to sodium hydroxide of 1:5.5, and then liquid-solid separation is performed to obtain a leaching solution and a leaching residue;

[0105] (2) to the immersion solution of step (1), add seed crystals of aluminum hydroxide twice, the first time add seed crystals of aluminum hydroxide with an average particle size D50 = 42 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 18%, the liquid-solid volume-mass ratio of the immersion solution to seed crystals of aluminum hydroxide is 1:0.55, age at 95°C for 2h, the second time add seed crystals of aluminum hydroxide with an average particle size D50 = 16 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 47%, the liquid-solid volume-mass ratio of the immersion solution to seed crystals of aluminum hydroxide is 1:0.38, age at 38°C for 2.5h, separate the liquid and solid, obtain aluminum hydroxide and aging solution, the aging solution is recycled to prepare sodium hydroxide solution in step (1) ;

[0106] (3) add the immersion residue of step (1) to the mother liquor after treatment in step (5), carry out secondary leaching according to a solid-liquid mass volume ratio of 1:17.5, a leaching temperature of 90°C, and a leaching time of 4h, separate the liquid and solid, obtain secondary immersion solution and secondary immersion residue;

[0107] (4) add ammonia water additive to the secondary immersion solution of step (3) according to a volume ratio of 1:2.5, react at 40°C for 1.5h, separate the liquid and solid, obtain sodium fluoride and mother liquor;

[0108] (5) regenerate the additive after recovery by cooling after rectification or distillation of the sodium fluoride mother liquor of step (4) at 92°C, the regeneration treatment ends when the recovery rate of the additive reaches 90%, obtain additive and treated mother liquor, the additive is recycled to step (4), and the treated mother liquor is recycled to step (3).

[0109] Example 6:

[0110] The embodiment provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, the electrolytic aluminum solid waste being overhaul residue, and the main components and contents of the electrolytic aluminum solid waste being the same as those in example 4.

[0111] The method comprises the following steps:

[0112] (1) crush and finely grind electrolytic aluminum solid waste with a particle size not greater than 150 μm, and carry out slurry in a solid-liquid mass volume ratio of 1:1 with an aqueous sodium hydroxide solution, add potassium persulfate cyanide breaker during the slurry process, leach at 200°C for 1h according to a molar ratio of aluminum to sodium hydroxide in the slurry of 1:6.5, separate the liquid and solid, obtain immersion solution and immersion residue;

[0113] (2) to the immersion solution of step (1), add seed crystals in two times, the first time, add seed crystals of aluminum hydroxide with an average particle size D50 = 39 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 7.5%, the liquid-solid volume-mass ratio of the immersion solution to the seed crystals of aluminum hydroxide is 1:0.47, and the aging is carried out at 70℃ for 4h, the second time, add seed crystals of aluminum hydroxide with an average particle size D50 = 19 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 44%, the liquid-solid volume-mass ratio of the immersion solution to the seed crystals of aluminum hydroxide is 1:0.42, and the aging is carried out at 32℃ for 1.5h, then separate the liquid and the solid, to obtain aluminum hydroxide and an aging solution, and the aging solution is recycled to prepare the sodium hydroxide solution in step (1) ;

[0114] (3) add the immersion residue of step (1) to the mother liquor after the treatment in step (5), and carry out secondary leaching according to a solid-liquid mass volume ratio of 1:12.5, a leaching temperature of 50℃, and a leaching time of 1.5h, then separate the liquid and the solid, to obtain secondary immersion solution and secondary immersion residue;

[0115] (4) add (ethanol, isopropyl alcohol with a mass ratio of 10:1) = additive to the secondary immersion solution of step (3) according to a volume ratio of 1:0.5, and react at 30℃ for 0.8h, then separate the liquid and the solid, to obtain sodium fluoride and a mother liquor;

[0116] (5) regenerate the additive by recycling the additive after the distillation of the sodium fluoride mother liquor of step (4) at 91℃, and the regeneration is ended when the recovery rate of the additive reaches 90%, to obtain the additive and a treated mother liquor, the additive is recycled to step (4), and the treated mother liquor is recycled to step (3).

[0117] Example 7:

[0118] The embodiment provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, and the electrolytic aluminum solid waste is carbon residue, and main components and contents of the electrolytic aluminum solid waste are as follows: Al 9.49wt%, F 6.51wt%, Na 4.83wt%, K 1.27wt%, Ca 1.42wt%, Mg 0.092wt%, Si 0.057wt%, and C 19.16wt%.

[0119] The method comprises the following steps:

[0120] (1) after being crushed and finely ground, electrolytic aluminum solid waste with a particle size of no more than 120 μm is slurried with a sodium hydroxide aqueous solution according to a solid-liquid mass volume ratio of 1:3, a sodium perchlorate cyanide breaker is added in the slurry process, leaching is carried out at 150℃ for 2h according to a molar ratio of aluminum to sodium hydroxide in the slurry of 1:5.2, and then the liquid and the solid are separated, to obtain an immersion solution and an immersion residue;

[0121] (2) to the immersion solution of step (1), add seed crystals twice, the first time, add seed crystals of aluminum hydroxide with an average particle size D50 = 31 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 9%, the liquid-solid volume-mass ratio of the immersion solution to the seed crystals of aluminum hydroxide is 1:0.55, age at 90°C for 2.2 h, the second time, add seed crystals of aluminum hydroxide with an average particle size D50 = 17 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 35.5%, the liquid-solid volume-mass ratio of the immersion solution to the seed crystals of aluminum hydroxide is 1:0.38, age at 38°C for 3 h, separate the liquid and the solid, obtain aluminum hydroxide and aging solution, and the aging solution is recycled to prepare the sodium hydroxide solution in step (1) ;

[0122] (3) add the immersion residue of step (1) to the mother liquor after treatment in step (5), and perform secondary leaching according to a solid-liquid mass volume ratio of 1:18, a leaching temperature of 25°C, and a leaching time of 3.5 h, separate the liquid and the solid, and obtain secondary immersion solution and secondary immersion residue;

[0123] (4) add an ethanol additive to the secondary immersion solution of step (3) according to a volume ratio of 1:3.5, and react at 32.5°C for 1.8 h, separate the liquid and the solid, and obtain sodium fluoride and mother liquor;

[0124] (5) regenerate the additive after the sodium fluoride mother liquor of step (4) is cooled after rectification or distillation at 92.5°C, the regeneration treatment is ended when the additive recovery rate reaches 90%, and the additive and the treated mother liquor are obtained, the additive is recycled to step (4), and the treated mother liquor is recycled to step (3).

[0125] Example 8:

[0126] The embodiment provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, the electrolytic aluminum solid waste is carbon residue, and main components and contents thereof are the same as those in example 7.

[0127] The method comprises the following steps:

[0128] (1) after being crushed and finely ground, electrolytic aluminum solid waste with a particle size of no more than 120 μm is slurried with a sodium hydroxide aqueous solution according to a solid-liquid mass volume ratio of 1:1.2, a sodium perchlorate cyanide breaker is added during the slurry process, leaching is performed according to a molar ratio of aluminum to sodium hydroxide in the slurry of 1:4.4 at 120°C for 1.5 h, the liquid and the solid are separated, and immersion solution and immersion residue are obtained;

[0129] (2) to the immersion solution of step (1), add seed crystals in two times, the first time, add seed crystals of aluminum hydroxide with an average particle size D50 = 33 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 10%, the liquid-solid volume-mass ratio of the immersion solution to the seed crystals of aluminum hydroxide is 1:0.56, age at 90℃ for 2.8h, the second time, add seed crystals of aluminum hydroxide with an average particle size D50 = 16 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 49%, the liquid-solid volume-mass ratio of the immersion solution to the seed crystals of aluminum hydroxide is 1:0.33, age at 46℃ for 2.5h, separate the liquid and the solid, obtain aluminum hydroxide and aging solution, the aging solution is recycled to prepare sodium hydroxide solution in step (1) ;

[0130] (3) add the immersion residue of step (1) to the mother liquor after treatment in step (5), carry out secondary leaching according to a solid-liquid mass volume ratio of 1:23, a leaching temperature of 80℃ and a leaching time of 2.75h, separate the liquid and the solid, obtain secondary immersion solution and secondary immersion residue;

[0131] (4) to the secondary immersion solution of step (3), add (methanol, isopropyl alcohol mass ratio 1:1) additive according to a volume ratio of 1:0.85 at 37.5℃ for 1.75h, separate the liquid and the solid, obtain sodium fluoride and mother liquor;

[0132] (5) regenerate the additive after the recovery of the additive from the sodium fluoride mother liquor of step (4) by rectification or distillation at 93.5℃ and cooling, the regeneration treatment is ended when the recovery rate of the additive reaches 90%, obtain the additive and treated mother liquor, the additive is recycled to step (4), and the treated mother liquor is recycled to step (3).

[0133] Example 9:

[0134] The present embodiment provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, which is carbon residue, and the main components and contents thereof are the same as those of example 7.

[0135] The method comprises the following steps:

[0136] (1) after crushing and grinding, electrolytic aluminum solid waste with a particle size not greater than 120 μm is slurried with sodium hydroxide aqueous solution at a solid-liquid mass volume ratio of 1:4.5, add calcium hypochlorite cyanide breaker during the slurry process, leach at 135℃ for 3h according to a molar ratio of aluminum to sodium hydroxide in the slurry of 1:5.6, separate the liquid and the solid, obtain immersion solution and immersion residue;

[0137] (2) to the immersion solution of step (1), add seed crystals in two times, the first time, add seed crystals of aluminum hydroxide with an average particle size D50 = 34 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 14.5%, the liquid-solid volume-mass ratio of the immersion solution to the seed crystals of aluminum hydroxide is 1:0.59, and the aging is carried out at 90°C for 2.4 h, the second time, add seed crystals of aluminum hydroxide with an average particle size D50 = 17.8 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 42.5%, the liquid-solid volume-mass ratio of the immersion solution to the seed crystals of aluminum hydroxide is 1:0.46, and the aging is carried out at 38.5°C for 1.8 h, then separate the liquid and the solid, to obtain aluminum hydroxide and an aging solution, and the aging solution is recycled to prepare the sodium hydroxide solution in step (1) ;

[0138] (3) add the immersion residue of step (1) to the mother liquor after the treatment in step (5), and carry out secondary leaching according to a solid-liquid mass volume ratio of 1:18.5, a leaching temperature of 60°C, and a leaching time of 3.7 h, then separate the liquid and the solid, to obtain secondary leaching solution and secondary leaching residue;

[0139] (4) add a methanol additive to the secondary leaching solution of step (3) according to a volume ratio of 1:0.88, and react at 42.6°C for 1.7 h, then separate the liquid and the solid, to obtain sodium fluoride and a mother liquor;

[0140] (5) regenerate the additive by recycling the additive after the cooling of the sodium fluoride mother liquor after the rectification or distillation at 85°C, and the regeneration is ended when the recovery rate of the additive reaches 90%, to obtain the additive and a treated mother liquor, and the additive is recycled to step (4), and the treated mother liquor is recycled to step (3).

[0141] Example 10:

[0142] The embodiment provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, and the electrolytic aluminum solid waste is aluminum electrolyte, overhaul residue and carbon residue, and main components and contents of the electrolytic aluminum solid waste are as follows: Al 17.85wt%, F 18.29wt%, Na 8.41wt%, K 1.74wt%, Ca 3.26wt%, Mg 0.25wt%, Si 5.83wt%, and C 6.92wt%.

[0143] The method comprises the following steps:

[0144] (1) after crushing and grinding, electrolytic aluminum solid waste with a particle size not greater than 74 μm is slurried with a sodium hydroxide aqueous solution according to a solid-liquid mass volume ratio of 1:3.2, a cyanide breaker of potassium peroxide is added in the slurry process, leaching is carried out at 115°C for 2.8 h according to a molar ratio of aluminum to sodium hydroxide in the slurry of 1:6.5, and then the liquid and the solid are separated, to obtain an immersion solution and an immersion residue;

[0145] (2) to the immersion solution of step (1), add seed crystals in two times, the first time, add seed crystals of aluminum hydroxide with an average particle size D50 = 42 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 18.5%, the liquid-solid volume-mass ratio of the immersion solution to seed crystals of aluminum hydroxide is 1:0.57, and the aging is carried out at 65°C for 3.5h, the second time, add seed crystals of aluminum hydroxide with an average particle size D50 = 22 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 48%, the liquid-solid volume-mass ratio of the immersion solution to seed crystals of aluminum hydroxide is 1:0.52, and the aging is carried out at 47.5°C for 3.2h, then separate the liquid and solid, to obtain aluminum hydroxide and an aging solution, and the aging solution is recycled to prepare the sodium hydroxide solution in step (1) ;

[0146] (3) add the immersion residue of step (1) to the mother liquor after treatment in step (5), and carry out secondary leaching according to a solid-liquid mass volume ratio of 1:13.5, a leaching temperature of 50°C, and a leaching time of 3.4h, then separate the liquid and solid, to obtain secondary immersion solution and secondary immersion residue;

[0147] (4) add isopropyl alcohol additive to the secondary immersion solution of step (3) according to a volume ratio of 1:2.5, and react at 37°C for 1.25h, then separate the liquid and solid, to obtain sodium fluoride and a mother liquor;

[0148] (5) regenerate the additive after the recovery of the additive by subjecting the sodium fluoride mother liquor of step (4) to rectification or distillation at 84°C and then cooling, and the regeneration is ended when the recovery rate of the additive reaches 90%, to obtain the additive and a treated mother liquor, and the additive is recycled to step (4) and the treated mother liquor is recycled to step (3).

[0149] Example 11:

[0150] The present embodiment provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, which is aluminum electrolyte, overhaul residue and carbon residue, and the main components and contents thereof are the same as those in Example 10.

[0151] The method comprises the following steps:

[0152] (1) after crushing and grinding, electrolytic aluminum solid waste with a particle size not greater than 74 μm is slurried with an aqueous sodium hydroxide solution according to a solid-liquid mass volume ratio of 1:4.1, hypochloric acid and perchloric acid are added as cyanide-breaking agents during the slurry process, leaching is carried out according to a molar ratio of aluminum to sodium hydroxide in the slurry of 1:6.9 at 105°C for 2.5h, then separate the liquid and solid, to obtain an immersion solution and an immersion residue;

[0153] (2) to the immersion solution of step (1), add seed crystals in two times, the first time, add seed crystals of aluminum hydroxide with an average particle size D50 = 45 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 13.5%, the liquid-solid volume-mass ratio of the immersion solution to seed crystals of aluminum hydroxide is 1:0.46, and the aging is carried out at 70°C for 3.2h, the second time, add seed crystals of aluminum hydroxide with an average particle size D50 = 23.5 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 47%, the liquid-solid volume-mass ratio of the immersion solution to seed crystals of aluminum hydroxide is 1:0.36, and the aging is carried out at 42.5°C for 2.6h, then separate the liquid and solid, to obtain aluminum hydroxide and an aging solution, and the aging solution is recycled to prepare the sodium hydroxide solution in step (1) ;

[0154] (3) add the immersion residue of step (1) to the mother liquor after treatment in step (5), and carry out secondary leaching according to a solid-liquid mass volume ratio of 1:15.5, a leaching temperature of 40°C, and a leaching time of 4.2h, then separate the liquid and solid, to obtain secondary leaching solution and secondary leaching residue;

[0155] (4) add ammonia water additive to the secondary leaching solution of step (3) according to a volume ratio of 1:2.85, and react at 38.6°C for 1.85h, then separate the liquid and solid, to obtain sodium fluoride and a mother liquor;

[0156] (5) regenerate the additive after recovery by subjecting the sodium fluoride mother liquor of step (4) to rectification or distillation at 82°C and then cooling, and the regeneration is ended when the recovery rate of the additive reaches 90%, to obtain the additive and a treated mother liquor, and the additive is recycled to step (4) and the treated mother liquor is recycled to step (3).

[0157] Example 12:

[0158] The present embodiment provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, which is aluminum electrolyte, overhaul residue and carbon residue, and the main components and contents thereof are the same as those in Example 10.

[0159] The method comprises the following steps:

[0160] (1) after crushing and grinding, electrolytic aluminum solid waste with a particle size not greater than 74 μm is slurried with a sodium hydroxide aqueous solution according to a solid-liquid mass volume ratio of 1:3.75, sodium persulfate is added during the slurry process to break cyanide, leaching is carried out at 135°C for 1.85h according to a molar ratio of aluminum to sodium hydroxide in the slurry of 1:5.85, and then the liquid and solid are separated, to obtain an immersion solution and an immersion residue;

[0161] (2) to the solution of step (1), add seed crystals twice, the first time add seed crystals of aluminum hydroxide with an average particle size D50 = 48.5 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 11.5%, the liquid-solid volume-mass ratio of the solution to the seed crystals of aluminum hydroxide is 1:0.38, age at 77°C for 3.9 h, the second time add seed crystals of aluminum hydroxide with an average particle size D50 = 19.8 μm, the volume fraction of seed crystals of aluminum hydroxide with a particle size < 15 μm is 38.5%, the liquid-solid volume-mass ratio of the solution to the seed crystals of aluminum hydroxide is 1:0.43, age at 33.5°C for 2.7 h, separate the liquid from the solid, obtain aluminum hydroxide and aging solution, the aging solution is recycled to prepare the sodium hydroxide solution of step (1) ;

[0162] (3) add the leaching residue of step (1) to the mother liquor after treatment of step (5), carry out secondary leaching according to a solid-liquid mass volume ratio of 1:16.5, a leaching temperature of 35°C, and a leaching time of 4.95 h, separate the liquid from the solid, obtain secondary leaching solution and secondary leaching residue;

[0163] (4) to the secondary leaching solution of step (3), add methanol additive according to a volume ratio of 1:2.83, react at 33°C for 2.85 h, separate the liquid from the solid, obtain sodium fluoride and mother liquor;

[0164] (5) regenerate the additive after the sodium fluoride mother liquor of step (4) is cooled after rectification or distillation at 94°C, the regeneration treatment ends when the additive recovery rate reaches 90%, obtain the additive and treated mother liquor, the additive is recycled to step (4), and the treated mother liquor is recycled to step (3).

[0165] Comparative Example 1

[0166] This comparative example provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, the raw materials and method refer to Example 1, the only difference is that step (2) does not add seed crystals twice.

[0167] Comparative Example 2

[0168] This comparative example provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, the raw materials and method refer to Example 1, the only difference is that step (2) does not add seed crystals twice.

[0169] Comparative Example 3

[0170] This comparative example provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, the raw materials and method refer to Example 1, the only difference is that step (2) does not add seed crystals twice.

[0171] Comparative Example 4

[0172] The comparative example 1 provides a method for recovering aluminum and fluorine from electrolytic aluminum solid waste, and the raw material and method refer to the example 1, and the only difference is that the particle size D50 of the first added seed crystal in step (2) is 15 μm, and the volume ratio of the seed crystal aluminum hydroxide particle size <15 μm is 40%, that is, the same as the second added seed crystal.

[0173] The liquid phase and solid phase aluminum and fluorine contents in the examples 1-12 and the comparative examples 1-4 are measured, the leaching rate, recovery rate and product purity of fluorine and aluminum are calculated, and the test results are shown in Table 1.

[0174] Table 1

[0175]

[0176] It can be seen from the above examples that the method of the present application uses strong alkali and water to deeply leach aluminum and fluorine in multiple steps, thereby improving the leaching rate and recovery rate of aluminum and fluorine. The leaching solution is converted into aluminum hydroxide and sodium fluoride products by two times of seed crystal aging and additive reaction, and the recovery rate of aluminum and fluorine can reach more than 90%, and the product purity of aluminum and fluorine can reach more than 98% and 99% respectively. The leaching agent and product conversion additive of the method of the present application can be recycled, reducing the amount of acid used in the leaching agent, and the production cost is low, the process is clean and pollution-free, and has a broad application prospect. Compared with example 1, comparative examples 1 and 2 only perform one aging or two aging respectively, the recovery rate of aluminum in comparative example 1 is low, and the recovery rate of aluminum in comparative example 2 is low, and the product purity of aluminum is also low. Compared with example 1, comparative examples 3 and 4 respectively increase the seed crystal particle size of the second aging and reduce the seed crystal particle size of the first aging, the recovery rate of aluminum in comparative example 3 is low, and the product purity in comparative example 4 is low.

[0177] The applicant declares that the above examples illustrate the detailed structural features of the present application, but the present application is not limited to the above detailed structural features, that is, it does not mean that the present application must rely on the above detailed structural features to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of the components selected by the present application, addition of auxiliary components, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.

[0178] The above describes the preferred embodiments of the present application, but the present application is not limited to the specific details in the above embodiments, and within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, and these simple modifications all belong to the protection scope of the present application.

[0179] In addition, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combination manners.

[0180] Furthermore, the various embodiments can also be combined, if not in contradiction, as long as they do not deviate from the spirit of the present application, which should be considered as disclosed.

Claims

1. A method for recovering aluminum and fluorine from electrolytic aluminum solid waste, characterized in that, The method includes the following steps: (1) Electrolytic aluminum solid waste is mixed with alkaline solution for pulping leaching, and after liquid-solid separation, leaching solution and leaching residue are obtained; (2) Add seed crystals to the leaching solution in step (1) for aging, and obtain aluminum hydroxide and aging solution after liquid-solid separation; (3) The leaching residue from step (1) is subjected to a second water leaching, and after liquid-solid separation, a second leaching solution and a second leaching residue are obtained. (4) Add additives to the secondary leaching solution in step (3) and react them. After liquid-solid separation, sodium fluoride and mother liquor are obtained. (5) The mother liquor in step (4) is regenerated to obtain an additive and a treated mother liquor. The additive is reused in step (4), and the treated mother liquor is reused in step (3) for a second water immersion. The alkaline solution in step (1) includes an aqueous solution of sodium hydroxide; The mass-to-volume ratio of the electrolytic aluminum solid waste to the alkaline solution in step (1) is 1:(0.5~6); In step (1), the molar ratio of aluminum to sodium hydroxide in the pulping process is 1:(4~8); The slurry leaching in step (1) is carried out at a temperature of 60~250℃ for 0.5~5 h. The aging process in step (2) includes adding a first seed crystal to the leaching solution in step (1) for a first aging process, and then adding a second seed crystal for a second aging process; the first seed crystal is aluminum hydroxide with an average particle size D50 of 30~50μm; the second seed crystal is aluminum hydroxide with an average particle size D50 of 15~25μm. The aging solution described in step (2) is reused in step (1) to prepare the alkaline solution; The additives in step (4) include any one or a combination of at least two of methanol, ethanol, isopropanol and ammonia.

2. The method for recovering aluminum and fluorine from electrolytic aluminum solid waste according to claim 1, characterized in that, The mass-to-volume ratio of the electrolytic aluminum solid waste to the alkaline solution in step (1) is 1:(1~3).

3. The method for recovering aluminum and fluorine from electrolytic aluminum solid waste according to claim 1, characterized in that, The volume percentage of aluminum hydroxide particles with a diameter <15μm in the first seed crystal is 5~20%.

4. The method for recovering aluminum and fluorine from electrolytic aluminum solid waste according to claim 1, characterized in that, The volume-to-mass ratio of the leaching solution to the first seed crystal is 1:(0.3~0.6).

5. The method for recovering aluminum and fluorine from electrolytic aluminum solid waste according to claim 1, characterized in that, The first aging temperature is 60~100℃, and the time is 1~5h.

6. The method for recovering aluminum and fluorine from electrolytic aluminum solid waste according to claim 1, characterized in that, In the second seed crystal, the volume percentage of aluminum hydroxide particles with a diameter <15μm is 30~50%.

7. The method for recovering aluminum and fluorine from electrolytic aluminum solid waste according to claim 1, characterized in that, The volume-to-mass ratio of the leaching solution to the second seed crystal is 1:(0.3~0.6).

8. The method for recovering aluminum and fluorine from electrolytic aluminum solid waste according to claim 1, characterized in that, The second aging temperature is 30~50℃, and the time is 1~5h.

9. The method for recovering aluminum and fluorine from electrolytic aluminum solid waste according to claim 1, characterized in that, The solid-liquid mass-volume ratio of the secondary water immersion in step (3) is 1:(10~25).

10. The method for recovering aluminum and fluorine from electrolytic aluminum solid waste according to claim 1, characterized in that, The temperature of the secondary water immersion in step (3) is 20~100℃ and the time is 0.5~5h.

11. The method for recovering aluminum and fluorine from electrolytic aluminum solid waste according to claim 1, characterized in that, The volume ratio of the secondary extract to the additive in step (4) is 1:(0.3~3).

12. The method for recovering aluminum and fluorine from electrolytic aluminum solid waste according to claim 1, characterized in that, The reaction temperature in step (4) is 25~45℃ and the time is 0.25~2h.

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