Disposal methods of fluorine-containing solid waste in aluminum industry

Abstract

The present invention discloses a method for disposing of fluorine-containing solid waste in the aluminum industry. The method is to add concentrated sulfuric acid to the fluorine-containing solid waste and then carry out negative-pressure roasting, so that the fluorine compound reacts with the concentrated sulfuric acid to generate hydrogen fluoride gas, greatly improving the conversion rate of fluorine, and increasing the conversion rate of fluorine to more than 90%. Compared with the existing wet process for extracting fluorine, since a large amount of aluminum sulfate can be generated during the roasting process, it can provide a sufficient amount of Al<supgt;3+< / supgt; in the subsequent leaching process to promote the decomposition of a small amount of residual fluoride compounds, and there is no need to add aluminum salts additionally at all. It can also reduce the amount of alkali used in the neutralization process (aluminum salts need to be neutralized with alkali, and the more aluminum salts, the greater the amount of alkali used), reduce the use of aluminum salts and alkali, lower the material cost, and also reduce the generation of low-value sodium salts to a certain extent.

Description

Technical Field

[0001] The invention relates to the field of fluorine-containing solid waste disposal, and in particular to a method for disposing fluorine-containing solid waste in the aluminum industry. Background Art

[0002] Aluminum is the second largest metal after steel in terms of consumption. It is widely used in construction, packaging, transportation, electricity, aerospace and other fields. It is one of the important basic raw materials indispensable for the development of national economic construction, strategic emerging industries and national defense science and technology industries. As the world's largest aluminum producer and consumer, my country's primary aluminum production will reach about 41 million tons in 2023, accounting for more than 55% of the world's production. However, with the development of the aluminum industry, the fluorine-containing solid waste generated in the aluminum electrolysis process has also increased significantly. The fluorine-containing solid waste mainly includes waste electrolyte, electrolyte wet lithium extraction leaching slag (black mud) and carbon slag flotation electrolyte (flotation ice).

[0003] Fluoride-containing solid waste generally has leaching toxicity and will pollute the environment if not effectively utilized or disposed of. In addition, fluoride, as an important chemical raw material, plays an important role in the national economy. At present, the main fluorine source for fluoride production is fluorite, and fluorite natural resources are limited and have become a national strategic resource. Therefore, the effective treatment and utilization of fluoride-containing solid waste is crucial to the replenishment of fluorine resources and the environment.

[0004] At present, there is no mature technology for the treatment of fluorine-containing solid waste from the aluminum industry. The research on solid waste from the aluminum industry mainly focuses on the wet extraction of lithium from electrolytes. The amount of leaching residue after lithium extraction is still very large. Some people have proposed to use the fluorine-containing leaching residue after lithium extraction directly in aluminum industry production to replace part of aluminum fluoride for adjusting the molecular ratio of electrolytes. However, due to the high sodium content in the leaching residue and the large amount of leaching residue, more electrolyte solid waste is bound to be generated in production. In addition, when extracting lithium from solid waste from the aluminum industry, soluble aluminum salts (such as aluminum chloride) are usually added to use the soluble aluminum salts and F + Complexation is used to promote the decomposition of fluoride to achieve fluorine resource utilization. However, this disposal method often requires a large amount of soluble aluminum salts, and a large amount of alkali is needed to neutralize the aluminum salts. The material cost is high and the fluorine conversion rate is generally low. Therefore, how to reasonably dispose of fluorine-containing solid waste and ensure the fluorine conversion rate is still a problem that plagues the industry. Summary of the invention

[0005] In view of this, the present invention proposes a method for disposing fluorine-containing solid waste in the aluminum industry. The method increases the fluorine conversion rate to more than 90% by roasting the fluorine-containing solid waste with concentrated sulfuric acid under negative pressure conditions. This method has important economic significance and promotion value for the treatment of fluorine-containing solid waste.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The method for disposing fluorine-containing solid waste from the aluminum industry of the present invention comprises adding concentrated sulfuric acid to the fluorine-containing solid waste for negative pressure roasting, and specifically comprises the following steps:

[0008] The first step is to add concentrated sulfuric acid with a concentration of 80% to 98% to the fluorine-containing solid waste, and then roast it in a negative pressure environment and recover the hydrogen fluoride gas generated during the roasting process; wherein the pressure of the roasting environment is -1kPa to -95kPa, the roasting temperature is 100 to 290°C, and the roasting time is ≤12h;

[0009] The second step is to add water to the calcined reaction residue and stir for 5 to 300 minutes to leach the fluorine in the reaction residue; after the leaching is completed, solid-liquid separation is performed to obtain a first filtrate containing fluorine ions and a first filter residue;

[0010] The third step is to neutralize the first filtrate to a pH of 4.0 to 8.0 using a neutralizing agent, and filter to obtain a second filter residue and a second filtrate. The second filter residue includes hydroxyaluminum fluoride and aluminum hydroxide, which can be used as a raw material for producing aluminum fluoride; and evaporate and crystallize the second filtrate to obtain sulfate.

[0011] The beneficial effect is that the present invention mixes fluorine-containing solid waste (of course, it can also be fluorine-containing hazardous waste) and concentrated sulfuric acid and then roasts them in a negative pressure environment, so that the fluorine compound and concentrated sulfuric acid react as much as possible to generate HF, which greatly improves the fluorine conversion rate and increases the fluorine conversion rate to more than 90%. Compared with the existing wet fluorine extraction process, since a large amount of aluminum sulfate can be produced during the roasting process, sufficient Al can be provided in the subsequent leaching process. 3+ , in order to promote the decomposition of a small amount of residual fluoride, there is no need to add additional aluminum salt. It can also reduce the amount of alkali used in the neutralization process, reduce the amount of materials used, reduce material costs, and to a certain extent reduce the generation of low-value sodium salts.

[0012] Preferably, the amount of concentrated sulfuric acid in the first step is 1 to 5 times the theoretical yield of sulfate converted from fluorine-containing solid waste. More preferably, the amount of concentrated sulfuric acid used is 1.1 to 2 times the theoretical yield of sulfate converted from fluorine-containing solid waste. An appropriate excess of concentrated sulfuric acid can meet the reaction requirements and ensure complete reaction.

[0013] Preferably, the calcination time in the first step is 5 min to 300 min. More preferably, the calcination time in the first step is controlled within the range of 60 min to 300 min to make the reaction as complete as possible.

[0014] The neutralizing agent in the third step is sodium hydroxide, 10% to 28% ammonia water or ammonia gas, the liquid-solid ratio of the neutralizing agent to the first filter residue is 1:1 to 10:1, and the leaching temperature is 20°C to 150°C. 3+ It exists in the form of precipitation to achieve the separation of fluorine compounds and sulfates.

[0015] Preferably, the fluorine-containing solid waste in the first step includes any one or a combination of two or more of fluorine-containing waste electrolyte, electrolyte wet lithium extraction leaching residue (black mud) and carbon slag flotation electrolyte (flotation ice). The disposal method of the present invention is suitable for disposing of various fluorine-containing solid wastes, has a wide range of applications, and is conducive to promotion.

[0016] Compared with the prior art, the advantages of the present invention are as follows: the present invention mixes fluorine-containing solid waste (of course, it can also be fluorine-containing hazardous waste) and concentrated sulfuric acid and then roasts them in a negative pressure environment, so that the fluorine compound and the concentrated sulfuric acid react, which greatly improves the conversion rate of fluorine and increases the conversion rate of fluorine to more than 90%;

[0017] Compared with the existing wet fluorine extraction process, a large amount of aluminum sulfate can be produced during the roasting process, which can provide sufficient Al in the subsequent leaching process. 3+ , in order to promote the decomposition of a small amount of residual fluoride, there is no need to add additional aluminum salt, and it can also reduce the amount of alkali used in the neutralization process (aluminum salt needs to be neutralized with alkali, the more aluminum salt, the greater the amount of alkali required), reduce material usage, reduce material costs, and to a certain extent reduce the generation of low-value sodium salts. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a process flow chart of the present invention.

[0019] Figure 2 It is the XRD spectrum of the first filter residue of the present invention. DETAILED DESCRIPTION

[0020] The present invention is described in more detail below with reference to specific embodiments. It should be noted that the fluorine-containing solid waste in the present invention includes but is not limited to one or a combination of two or more of fluorine-containing waste electrolyte, electrolyte wet lithium extraction leaching residue (black mud) and carbon residue flotation electrolyte (flotation ice).

[0021] The present invention proposes a method for treating fluorine-containing solid waste from aluminum industry. The method includes first adding concentrated sulfuric acid to the fluorine-containing solid waste for negative pressure roasting. The process flow is shown in FIG. Figure 1 , as follows:

[0022] The first step is to add concentrated sulfuric acid with a concentration of 80% to 98% to the fluorine-containing solid waste, and then roast the fluorine-containing solid waste with concentrated sulfuric acid in a negative pressure environment, and recover the hydrogen fluoride (in the form of gas) generated during the roasting process; wherein the pressure of the roasting environment is -1kPa to -95kPa, the roasting temperature is 100 to 290°C, and the roasting time is 0 to 24h (the roasting time is preferably 5 to 300min, and more preferably 60 to 300min);

[0023] The amount of concentrated sulfuric acid added is determined according to the theoretical yield of sulfate converted from fluorine-containing solid waste. The amount of concentrated sulfuric acid used is 1 to 5 times the theoretical yield of sulfate, preferably 1.1 to 2 times. An appropriate excess of concentrated sulfuric acid can meet the reaction requirements, ensure complete reaction, and avoid acid waste. During the negative pressure roasting process, the fluorine-containing compounds in the fluorine-containing solid waste react with concentrated sulfuric acid to obtain sulfate, HF and fluorine-containing salt. The specific reaction mechanism is as follows:

[0024] ;

[0025] ;

[0026] ;

[0027] ;

[0028] ;

[0029] ;

[0030] ;

[0031] The second step is to add water to the calcined reaction residue and stir for 5 to 30 minutes to leach the fluorine in the reaction residue; after the leaching is completed, solid-liquid separation is performed to obtain a first filtrate containing fluoride ions and a first filter residue; the stirring leaching time is 5 to 300 minutes, and the leaching temperature is 20° C. to 150° C. Among them, the main component of the first filter residue is alumina, and the content of alumina is above 88%, and even as high as 96%, which can be used as a raw material for building materials;

[0032] The third step is to use a neutralizing agent to neutralize the first filtrate to a pH of 4.0 to 8.0h, filter to obtain a second filter residue and a second filtrate, wherein the second filter residue includes hydroxyaluminum fluoride and aluminum hydroxide, which can be used as a raw material for producing aluminum fluoride, such as roasting in a hydrogen fluoride environment to obtain an aluminum fluoride product; evaporate and crystallize the second filtrate to obtain sulfate; wherein the neutralizing agent is sodium hydroxide, 10% to 28% ammonia water or ammonia gas, and the solid-liquid ratio of the neutralizing agent to the first filter residue is 1:1 to 10:1, and the neutralizing agent is used to make aluminum fluoride and Al 3+ Precipitation and subsequent separation from sulfate.

[0033] The present invention mixes fluorine-containing solid waste (of course, it can also be fluorine-containing hazardous waste) with concentrated sulfuric acid and then roasts it in a negative pressure environment. The large amount of aluminum sulfate that has been formed is decomposed by cryolite. During the leaching process, the aluminum sulfate can self-supply a sufficient amount of Al 3+ , in order to promote the decomposition of a small amount of residual fluoride, not only does it not need to add additional aluminum salt, but it also avoids the need to add a large amount of alkali in the subsequent neutralization process to react with the added aluminum salt, thereby reducing material usage, reducing material costs, and also reducing the generation of low-value sodium salts to a certain extent.

[0034] Example 1

[0035] In this embodiment, carbon slag flotation electrolyte (flotation ice) is used as raw material and treated by the method of the present invention, wherein the main components of the carbon slag flotation electrolyte (flotation ice) are shown in Table 1.

[0036] Table 1 Main components of carbon slag flotation electrolyte (flotation ice) in this example

[0037]

[0038] Add 160 mL of 98% concentrated sulfuric acid to 200 g of the raw material, mix and roast at 130°C for 150 min under negative pressure, with a pressure of -95 kPa. Collect hydrogen fluoride gas during the roasting process and use it as a raw material for fluorine chemical industry. After the roasting, return to normal pressure to obtain 409.42 g of reaction slag. Among them, the conversion rate of fluorine = (fluorine in hydrogen fluoride / total fluorine in the raw material) × 100% = 91.5%;

[0039] Add 2000 mL of water to the reaction residue obtained by roasting, stir and leach at 20° C. for 300 min at a stirring speed of 200 rpm; filter after the leaching is completed to obtain a first filter residue and a first filtrate containing fluoride ions;

[0040] The mass of the first filter residue after washing and drying is 7.69 g. Figure 2 It can be seen that the first filter residue after washing and drying mainly includes alumina, which accounts for 6.88g, and the rest are oxides of magnesium, silicon, etc. and carbon powder. The content of alumina in the first filter residue is as high as over 92.4%, and it can be used as a raw material for building materials.

[0041] The first filtrate is neutralized with 20% ammonia water to a pH of 7 to obtain a white slurry, which is then filtered again to obtain a second residue and a second filtrate. The second residue is a mixture of hydroxyaluminum fluoride and aluminum hydroxide, which can be used as a raw material for aluminum fluoride. The second filtrate contains soluble sulfates such as sodium sulfate, ammonium sulfate and lithium sulfate, and sodium sulfate and ammonium sulfate can be produced by evaporation. The evaporated concentrate is used to extract lithium salts.

[0042] Example 2

[0043] In this embodiment, electrolyte wet lithium extraction leaching residue (black mud) is used as raw material and treated by the method of the present invention, wherein the main components of electrolyte wet lithium extraction leaching residue (black mud) are shown in Table 2.

[0044] Table 2 Main components of the leaching residue (black mud) from the electrolyte wet lithium extraction process in this example

[0045]

[0046] Add 200 mL of 98% concentrated sulfuric acid to 200 g of the raw material, and roast at 180°C for 60 min under negative pressure. The pressure is -75 kPa. During the roasting process, hydrogen fluoride gas is collected and used as a raw material for fluorine chemical industry. After the roasting, the pressure is restored to normal pressure to obtain 434.57 g of reaction slag. The conversion rate of fluorine is calculated. Among them, the conversion rate of fluorine is 92.3%;

[0047] Add 1800 mL of water to the reaction residue obtained by roasting, stir and leach at 50° C. for 270 min at a stirring speed of 180 rpm; filter after leaching to obtain a first filter residue and a first filtrate containing fluoride ions; the mass of the first filter residue after washing and drying is 7.24 g, of which aluminum oxide is 6.56 g, and the rest is oxides of magnesium, silicon, iron, etc. and carbon powder, which can be used as a raw material for building materials;

[0048] The first filtrate is neutralized with 25% ammonia water to a pH of 6 to obtain a white slurry, which is then filtered to obtain a second filter residue and a second filtrate. The second filter residue is a mixture of hydroxyaluminum fluoride and aluminum hydroxide, which can be used as a raw material for aluminum fluoride. The second filtrate contains soluble sulfates such as sodium sulfate and ammonium sulfate, and sodium sulfate and ammonium sulfate can be prepared by evaporation.

[0049] Example 3

[0050] In this embodiment, waste electrolyte is used as raw material and is treated by the method of the present invention. The main components of the waste electrolyte in this embodiment are shown in Table 3.

[0051] Table 3 Main components of the waste electrolyte in this example

[0052]

[0053] Add 400 mL of 95% concentrated sulfuric acid to 200 g of the raw material, and calcine at 220° C. for 100 min under negative pressure, with a pressure of -60 kPa. During the calcination process, collect hydrogen fluoride gas and use it as a fluorine chemical raw material. After the calcination, return to normal pressure to obtain 734.28 g of reaction slag, and calculate the conversion rate of fluorine. Among them, the conversion rate of fluorine in this example is 91.8%;

[0054] Add 1500 mL of water to the reaction residue obtained by roasting, stir and leach at 70° C. for 200 min at a stirring speed of 130 rpm; filter after leaching to obtain a first filter residue and a first filtrate containing fluoride ions; wash and dry the first filter residue, the weight of the first filter residue is 7.23 g, of which alumina is 6.86 g, and can be used as a raw material for building materials;

[0055] The first filtrate is neutralized with 10% ammonia water to a pH of 6 to obtain a white slurry, which is filtered. The second filter residue is a mixture of hydroxyaluminum fluoride and aluminum hydroxide, which can be used as a raw material for aluminum fluoride. The second filtrate contains soluble sulfates such as sodium sulfate, ammonium sulfate and lithium sulfate, which can be produced by evaporation. The evaporated concentrated solution is used to extract lithium salts.

[0056] Example 4

[0057] In this embodiment, a mixture of carbon slag flotation electrolyte (flotation ice) and waste electrolyte is used as raw material and treated by the method of the present invention, wherein the main components of the mixed raw material are shown in Table 4.

[0058] Table 4 Main components of the mixed raw materials in this example

[0059]

[0060] Add 550 mL of 90% concentrated sulfuric acid to 200 g of the raw material, and calcine at 240° C. for 150 min under negative pressure, with a pressure of -50 kPa. Collect hydrogen fluoride gas during the calcination process and use it as a fluorine chemical raw material. After the calcination, return to normal pressure to obtain 922.72 g of reaction slag, and calculate the conversion rate of fluorine. Among them, the conversion rate of fluorine in this example is 93.1%;

[0061] 1000 mL of water was added to the reaction residue obtained by roasting, and the mixture was stirred and leached at 90° C. for 150 min at a stirring speed of 90 rpm. After leaching, the mixture was filtered to obtain a first filter residue and a first filtrate containing fluoride ions. The mass of the first filter residue after washing and drying was 7.56 g, of which alumina was 7.28 g, and the residue could be used as a raw material for building materials.

[0062] The first filtrate is neutralized with a 4M sodium hydroxide solution to a pH of 5 to obtain a white slurry, and the white slurry is filtered. The second filter residue is a mixture of hydroxyaluminum fluoride and aluminum hydroxide, which can be used as a raw material for aluminum fluoride; the second filtrate contains soluble sulfates such as sodium sulfate and lithium sulfate, and sodium sulfate can be produced by evaporation. The evaporated concentrated solution can be used to extract lithium salts.

[0063] Example 5

[0064] In this embodiment, a mixture of carbon slag flotation electrolyte (flotation ice) and electrolyte wet lithium extraction leaching residue (black mud) is used as a raw material and treated by the method of the present invention. The main components of the mixture are shown in Table 5.

[0065] Table 5 Main components of the mixture in this example

[0066]

[0067] 700 mL of 85% concentrated sulfuric acid was added to 200 g of the raw material, and the mixture was calcined at 280 °C for 200 min under negative pressure and a pressure of -30 kPa. During the calcination process, hydrogen fluoride gas was collected and used as a raw material for fluorine chemical industry. After the calcination, the mixture was returned to normal pressure to obtain 1085.32 g of reaction slag, and the conversion rate of fluorine was 91.9%.

[0068] Add 1500 mL of water to the reaction residue obtained by roasting, stir and leach at 110° C. for 100 min at a stirring speed of 50 rpm; filter after leaching to obtain a first filter residue and a first filtrate containing fluoride ions; the mass of the first filter residue after washing and drying is 7.31 g, of which alumina is 6.26 g, and can be used as a raw material for building materials;

[0069] The first filtrate is neutralized with a 2M sodium hydroxide solution to a pH of 6 to obtain a white slurry, and the white slurry is filtered. The second filter residue is a mixture of hydroxyaluminum fluoride and aluminum hydroxide, which can be used as a raw material for aluminum fluoride; the second filtrate contains soluble sulfates such as sodium sulfate and lithium sulfate, and sodium sulfate can be produced by evaporation. The evaporated concentrated solution can be used to extract lithium salts.

[0070] Comparative Example 1

[0071] Take 200g of the mixture in Example 5, add 700mL of 85% concentrated sulfuric acid, and roast at normal pressure and 280°C for 200min. During the roasting process, collect hydrogen fluoride gas and calculate the fluorine conversion rate, which is 73.8%. Comparing it with Example 5, it can be seen that the fluorine conversion rate of Example 5 is much greater than that of Comparative Example 1.

[0072] Example 6

[0073] In this embodiment, a mixture of electrolyte wet lithium extraction leaching residue (black mud) and waste electrolyte is used as raw material and treated by the method of the present invention. The main components of the mixture are shown in Table 6.

[0074] Table 6 Main components of the mixture in this example

[0075]

[0076] The above raw materials were crushed into 100 meshes, 500 mL of 98% concentrated sulfuric acid was added to 200 g of the raw materials, and the mixture was calcined at 290° C. for 270 min under negative pressure and a pressure of -10 kPa. During the calcination process, hydrogen fluoride gas was collected and used as a raw material for fluorine chemical industry. After the calcination, the mixture was returned to normal pressure to obtain 762.43 g of reaction slag, and the conversion rate of fluorine was calculated. Among them, the conversion rate of fluorine in this embodiment was 92.3%;

[0077] Add 2000 mL of water to the reaction residue obtained by roasting, stir and leach at 100° C. for 50 min at a stirring speed of 30 rpm; filter after leaching to obtain a first filter residue and a first filtrate containing fluoride ions; the mass of the first filter residue after washing and drying is 7.73 g, of which alumina is 6.82 g, and can be used as a raw material for building materials;

[0078] The first filtrate is neutralized with 0.1M sodium hydroxide solution to a pH of 7.5 to obtain a white slurry, and the white slurry is filtered. The second filter residue is a mixture of hydroxyaluminum fluoride and aluminum hydroxide, which can be used as a raw material for aluminum fluoride; the second filtrate contains soluble sulfates such as sodium sulfate and lithium sulfate, and sodium sulfate can be produced by evaporation. The evaporated concentrated solution can be used to extract lithium salts.

[0079] Comparative Example 2

[0080] Take 200g of the mixed material in Example 6, add 500mL of 98% concentrated sulfuric acid, and roast at normal pressure and 290°C for 270min. During the roasting process, collect hydrogen fluoride gas, and the fluorine conversion rate is 77.2%. Comparing it with Example 5, it can be seen that the fluorine conversion rate of Example 6 is much greater than that of Comparative Example 1.

[0081] Example 7

[0082] In this embodiment, a mixture of electrolyte wet lithium extraction leaching residue (black mud), carbon residue flotation electrolyte (flotation ice) and waste electrolyte is used as raw material and treated by the method of the present invention. The main components of the mixture are shown in Table 7.

[0083] Table 7 Main components of the mixture in this example

[0084]

[0085] The mixed material was crushed to 200 mesh, 900 mL of 90% concentrated sulfuric acid was added to 200 g of the raw material, and the mixture was calcined at 290° C. for 300 min under negative pressure and a pressure of -50 kPa. During the calcination process, hydrogen fluoride gas was collected and used as a raw material for fluorine chemical industry. After the calcination, the mixture was returned to normal pressure to obtain 1226.08 g of reaction slag, and the conversion rate of fluorine was calculated. Among them, the conversion rate of fluorine in this embodiment was 96.3%;

[0086] Add 1800 mL of water to the reaction residue obtained by roasting, stir and leach at 150° C. for 5 min at a stirring speed of 10 rpm; filter after leaching to obtain a first filter residue and a first filtrate containing fluoride ions; the mass of the first filter residue after washing and drying is 7.36 g, of which alumina is 6.63 g, which can be used as a raw material for building materials;

[0087] The first filtrate is neutralized with ammonia gas to a pH of 6 to obtain a white slurry, and the white slurry is filtered. The second filter residue is a mixture of hydroxyaluminum fluoride and aluminum hydroxide, which can be used as a raw material for aluminum fluoride; the second filtrate contains soluble sulfates such as sodium sulfate, ammonium sulfate and lithium sulfate, and sodium sulfate and ammonium sulfate can be produced by evaporation. The evaporated concentrated solution can be used to extract lithium salts.

[0088] Comparative Example 3

[0089] Take 200g of the raw material in Example 7, add 900mL of 90% concentrated sulfuric acid, and calcine at 290°C for 300min under normal pressure. During the calcination process, collect hydrogen fluoride gas and calculate the fluorine conversion rate. After calculation, the fluorine conversion rate of this comparative example is 76.8%, which is significantly lower than that of Example 7 of the present invention.

[0090] In summary, the present invention roasts fluorine-containing solid waste and concentrated sulfuric acid in a slightly negative pressure environment, which not only improves the conversion rate of HF, but also produces aluminum sulfate that provides sufficient Al for subsequent leaching. 3+ It is beneficial to the decomposition of residual fluoride and further promotes the resource utilization of fluorine in fluorine-containing solid waste, which has important economic significance and industrial promotion value.

Claims

1. A method for disposing fluorine-containing solid waste in aluminum industry, characterized by: The treatment method is to first add concentrated sulfuric acid to the fluorine-containing solid waste for negative pressure roasting, which specifically includes the following steps: The first step is to add concentrated sulfuric acid with a concentration of 80% to 98% to the fluorine-containing solid waste, roast it in a negative pressure environment and recover the hydrogen fluoride gas generated during the roasting process; wherein the pressure of the negative pressure environment is -30kPa to -95kPa, the roasting temperature is 100 to 290°C, and the roasting time is ≤12h; the amount of concentrated sulfuric acid added is 1.0 to 2 times the theoretical amount required for converting the fluorine-containing solid waste into sulfate; The second step is to add water to the calcined reaction residue and stir for 5 to 300 minutes to leach the fluorine in the reaction residue; after the leaching is completed, solid-liquid separation is performed to obtain a first filtrate containing fluorine ions and a first filter residue; The third step is to neutralize the first filtrate to a pH of 4.0 to 8.0 using a neutralizing agent, and filter to obtain a second filter residue and a second filtrate, wherein the second filter residue includes hydroxyaluminum fluoride and aluminum hydroxide; and evaporate and crystallize the second filtrate to obtain sulfate.

2. The method for disposing fluorine-containing solid waste from aluminum industry according to claim 1, characterized in that: In the first step, the amount of concentrated sulfuric acid added is 1.1 to 2 times the theoretical amount required to convert the fluorine-containing solid waste into sulfate.

3. The method for disposing fluorine-containing solid waste from aluminum industry according to claim 1, characterized in that: The calcination time in the first step is 5 min to 300 min.

4. The method for disposing fluorine-containing solid waste from aluminum industry according to claim 1, characterized in that: The neutralizing agent in the third step is sodium hydroxide, ammonia water or ammonia gas, and the liquid-solid ratio of the neutralizing agent to the first filter residue is 1:1 to 10:1; the leaching temperature is 20° C. to 150° C.

5. The method for disposing fluorine-containing solid waste from aluminum industry according to claim 1, characterized in that: The fluorine-containing solid waste in the first step includes any one or a combination of two or more of fluorine-containing waste electrolyte, electrolyte wet lithium extraction leaching residue and carbon residue flotation electrolyte.

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