A resource treatment method for hazardous carbon-containing waste from aluminum electrolysis

Abstract

The invention belongs to the technical field of aluminum electrolysis hazardous waste treatment, and specifically is a resource treatment method for aluminum electrolysis carbon-containing hazardous waste, which adopts high-temperature mechanical activation to assist in recovering carbon materials and fluorine-containing components in aluminum electrolysis carbon-containing hazardous waste, and uses a high-temperature ball milling device to construct a pressurized activation leaching system. On the one hand, the wet leaching process can be synergistically strengthened by mechanical activation and high-pressure environment, thereby improving the separation efficiency of carbon materials and fluorine-containing components; on the other hand, compared with the traditional mechanical activation→pressurized leaching, which needs to be completed in different equipment links, the process flow is effectively shortened, equipment investment and site occupation are saved, and the treatment efficiency is significantly improved; the leaching toxicity of aluminum electrolysis carbon-containing hazardous waste is fully utilized, a hydrofluoric acid-nitric acid / sulfuric acid / hydrochloric acid mixed leaching system is established, and the impurity removal capacity of the reaction system is further improved, and the fixed carbon content of the recovered carbon material is ≥98.5%, and the leaching rate of fluoride is ≥99.0%.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum electrolysis hazardous waste treatment, and in particular to a resource treatment method for aluminum electrolysis carbon-containing hazardous waste. Background Art

[0002] At present, the resource disposal methods of hazardous carbon-containing waste from aluminum electrolysis can be mainly divided into the following three categories:

[0003] (1) Resource utilization: The strong reducing property and high energy density of carbon materials in hazardous wastes containing carbon from aluminum electrolysis, as well as the flux properties of fluorides, can be directly applied to industries such as alumina production, steel production (blast furnace ironmaking, secondary refining, ferroalloy smelting), cement production, and glass production. This can reduce the cost of raw materials while achieving harmless disposal of cyanide / fluorine toxic substances. However, its disadvantage is that it cannot take into account the comprehensive utilization of graphite carbon and fluoride salts, resulting in unbalanced utilization of valuable resources and making it difficult to achieve large-scale promotion and application.

[0004] (2) Pyrometallurgical treatment: Utilizing the significant differences in saturated vapor pressure or boiling point of the complex inorganic salt system in the carbon-containing hazardous waste of aluminum electrolysis, high-temperature roasting, ultra-high temperature graphitization, vacuum distillation, microwave-high temperature roasting and other treatment methods are used to promote the electrolyte and other non-carbon components to be deintercalated in gaseous form and collected by condensation. The process is simple, the treatment efficiency is high, and the treatment volume per unit time is large. Its disadvantages are that it will generate huge energy consumption and carbon emissions, the investment cost of some high-temperature treatment equipment is extremely high, and the fluorine-containing flue gas has serious corrosiveness and environmental pollution risks.

[0005] (3) Wet treatment: Utilize the differences in chemical reaction characteristics of complex inorganic salt systems in hazardous waste containing carbon from aluminum electrolysis to construct H 2 O→NaOH→H + 、NaOH→H + , water → H + -Al 3+ / Fe 3+ The multi-stage wet leaching system can regulate the complex mineral phase and simultaneously recover graphite carbon and fluoride with high purity. The disadvantage is that the process is complicated and the waste liquid of wet treatment is prone to secondary pollution. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the main purpose of the present invention is to propose a method for resource treatment of carbon-containing hazardous waste from aluminum electrolysis, which can achieve safe dissociation of toxic substances while efficiently recovering valuable components (carbon materials and fluorine-containing components) in carbon-containing hazardous waste from aluminum electrolysis, and has the characteristics of simple process, high treatment efficiency and high resource utilization.

[0007] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0008] A method for recycling hazardous carbon-containing waste from aluminum electrolysis, comprising the following steps:

[0009] S1. Perform multi-stage crushing and screening of hazardous waste containing carbon from aluminum electrolysis to prepare raw materials for use;

[0010] S2. Add the unused raw materials into a high-temperature ball mill for high-temperature mechanical activation to obtain an activated material, the ball mill speed is 50~350 r / min, the activation time is 0.1~2.0h, and the activation temperature is 100~250℃;

[0011] S3. After the high-temperature mechanical activation is completed, a liquid reaction agent is added to the high-temperature ball mill for pressurized activation leaching; the activation speed is 100-300 r / min, the leaching time is 0.1-4.0h, and the leaching temperature is 120-240°C. After the leaching is completed, liquid-solid separation and ball material separation are performed in sequence to obtain acidic waste liquid and solid residue;

[0012] S4. The solid residue is subjected to water immersion treatment to obtain recovered carbon material and water immersion waste liquid; the water immersion temperature is 30~80℃, the water immersion time is 0.1~1.0h, and the liquid-to-solid ratio of water to the solid residue is 5~25 mL / g.

[0013] As a preferred solution of the resource treatment method of hazardous carbon-containing waste from aluminum electrolysis according to the present invention, the step S4 further includes:

[0014] S5. Adding solid aluminum salt to the acidic waste liquid produced in step S3 to precipitate, and performing solid-liquid separation to obtain a hydroxyaluminum fluoride product.

[0015] As a preferred embodiment of the resource treatment method of hazardous carbon-containing waste from aluminum electrolysis described in the present invention, in the step S1, the particle size of the raw material to be used is ≤0.15 mm.

[0016] As a preferred embodiment of the resource treatment method of carbon-containing hazardous waste from aluminum electrolysis described in the present invention, in step S1, the carbon-containing hazardous waste from aluminum electrolysis is carbon slag or waste cathode carbon blocks.

[0017] As a preferred embodiment of the resource treatment method of hazardous carbon-containing waste from aluminum electrolysis described in the present invention, in step S2, the top of the high-temperature mechanical activation device is equipped with an inlet / exhaust valve with a polytetrafluoroethylene lining.

[0018] As a preferred embodiment of the resource treatment method of hazardous carbon-containing waste from aluminum electrolysis described in the present invention, in step S2, if the raw material to be used is waste cathode carbon blocks, an oxidizing gas is introduced to carry out decyanation treatment.

[0019] As a preferred embodiment of the method for resource recovery of hazardous carbon-containing waste from aluminum electrolysis described in the present invention, in step S2, the oxidizing gas is air, oxygen-enriched gas or carbon dioxide.

[0020] As a preferred embodiment of the resource treatment method of hazardous carbon-containing waste from aluminum electrolysis described in the present invention, in step S3, the liquid reaction reagent is one or more of nitric acid, sulfuric acid, and hydrochloric acid.

[0021] As a preferred embodiment of the resource treatment method of hazardous carbon-containing waste from aluminum electrolysis described in the present invention, in step S3, the concentration of the liquid reaction agent is 2-12 mol / L, and the liquid-to-solid ratio of the liquid reaction agent to the activation material is 5-30 mL / g.

[0022] As a preferred embodiment of the resource treatment method of carbon-containing hazardous waste from aluminum electrolysis described in the present invention, wherein: in the step S4, the water leaching waste liquid includes strongly acidic water leaching waste liquid and weakly acidic water leaching waste liquid, wherein the strongly acidic water leaching waste liquid has a pH value of ≤2, and is mixed with the acidic waste liquid of step S3 to obtain a combined waste liquid, and the weakly acidic water leaching waste liquid has a pH value of >2 and is returned for water leaching treatment.

[0023] As a preferred embodiment of the resource treatment method of hazardous carbon-containing waste from aluminum electrolysis described in the present invention, in step S5, solid aluminum salt is added to the combined waste liquid, the pH value is adjusted to 3.5-6.5, the crystallization temperature is 40-90°C, and a precipitate is precipitated.

[0024] As a preferred embodiment of the resource treatment method of hazardous carbon-containing waste from aluminum electrolysis described in the present invention, in step S5, the solid aluminum salt is one or more of aluminum nitrate, aluminum sulfate or aluminum chloride.

[0025] The beneficial effects of the present invention are as follows:

[0026] The present invention proposes a resource treatment method for carbon-containing hazardous wastes from aluminum electrolysis, which adopts high-temperature mechanical activation to assist in recovering carbon materials and fluorine-containing components in the carbon-containing hazardous wastes from aluminum electrolysis, and uses a high-temperature ball mill to construct a pressurized activation leaching system. On the one hand, the wet leaching process can be synergistically enhanced by mechanical activation and a high-pressure environment to improve the separation efficiency of carbon materials and fluorine-containing components; on the other hand, compared with the traditional mechanical activation → pressurized leaching, which needs to be completed in different equipment links, the process flow is effectively shortened, equipment investment and site occupation are saved, and the treatment efficiency is significantly improved; the leaching toxicity of carbon-containing hazardous wastes from aluminum electrolysis is fully utilized to establish a hydrofluoric acid-nitric acid / sulfuric acid / hydrochloric acid mixed leaching system, and the impurity removal capacity of the reaction system is further improved, and the fixed carbon content of the recovered carbon material is ≥98.5%, and the leaching rate of fluoride is ≥99.0%. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0028] Figure 1 The present invention is a schematic flow chart of the method for resource recovery of hazardous carbon-containing waste from aluminum electrolysis.

[0029] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0030] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The present invention proposes a resource treatment method for carbon-containing hazardous waste from aluminum electrolysis, which uses high-temperature mechanical activation to assist in recovering carbon materials and fluorine-containing components from carbon-containing hazardous waste from aluminum electrolysis:

[0032] (1) High-temperature mechanical activation can not only improve the reactivity of the components contained in the carbon-containing hazardous waste from aluminum electrolysis, but also promote the decomposition of some simple compounds. It has the dual effects of mechanical activation and thermal activation, which is beneficial to the removal of non-carbon impurities in the activation leaching process.

[0033] (2) The pressurized activation leaching system was innovatively constructed using a high-temperature ball mill. On the one hand, the wet leaching process can be synergistically enhanced by mechanical activation and high-pressure environment, thereby improving the separation efficiency of carbon materials and fluorine-containing components. On the other hand, compared with the traditional mechanical activation → pressurized leaching, which needs to be completed in different equipment links, the process flow is effectively shortened, equipment investment and site occupation are saved, and the processing efficiency is significantly improved.

[0034] (3) Make full use of the leaching toxicity of carbon-containing hazardous waste from aluminum electrolysis, establish a hydrofluoric acid-nitric acid / sulfuric acid / hydrochloric acid mixed leaching system, further improve the impurity removal ability of the reaction system, and recover carbon materials with a fixed carbon content of ≥98.5% and a fluoride leaching rate of ≥99.0%.

[0035] (4) By adding aluminum salts, controlling pH value and temperature, hydroxyaluminum fluoride products can be extracted from acidic waste liquid, avoiding secondary pollution and realizing resource recovery of non-carbon valuable components of carbon-containing hazardous waste from aluminum electrolysis, among which the fluorine recovery rate is ≥98.0%.

[0036] According to one aspect of the present invention, the present invention provides the following technical solution:

[0037] like Figure 1 As shown, a method for recycling hazardous carbon-containing waste from aluminum electrolysis comprises the following steps:

[0038] S1. Perform multi-stage crushing and screening of hazardous waste containing carbon from aluminum electrolysis to prepare raw materials for use;

[0039] S2. Add the unused raw materials to a high-temperature ball mill for high-temperature mechanical activation to obtain an activated material, the ball mill speed is 50~350 r / min, the activation time is 0.1~2.0h, and the activation temperature is 100~250°C; specifically, the ball mill speed can be, for example but not limited to, any one of 50 r / min, 100 r / min, 150 r / min, 200 r / min, 250 r / min, 300 r / min, 350 r / min, or any range between two of them; the activation time can be, for example but not limited to, any one of 0.1h, 0.5h, 1.0h, 1.5h, 2.0h, or any range between two of them; the activation temperature can be, for example but not limited to, any one of 100°C, 150°C, 200°C, 250°C, or any range between two of them;

[0040] S3. After the high-temperature mechanical activation is completed, a liquid reaction agent is added to the high-temperature ball mill for pressurized activation and leaching; the activation speed is 100-300 r / min, the leaching time is 0.1-4.0h, the leaching temperature is 120-240°C, and after the leaching is completed, liquid-solid separation and ball material separation are performed in sequence to obtain acidic waste liquid and solid residue; specifically, the activation speed may be, for example but not limited to, any one of 100 r / min, 150 r / min, 200 r / min, 250 r / min, 300 r / min or any range between two thereof; the leaching time may be, for example but not limited to, any one of 0.1h, 0.5h, 1.0h, 1.5h, 2.0h, 2.5h, 3.0h, 3.5h, 4.0h or any range between two thereof;

[0041] S4. The solid residue is subjected to water immersion treatment to obtain recovered carbon materials and water immersion waste liquid; the water immersion temperature is 30-80°C, the water immersion time is 0.1-1.0h, and the liquid-to-solid ratio of water to solid residue is 5-25 mL / g. Specifically, the water immersion temperature can be, for example, but not limited to, any one of 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, or a range between any two of them; the water immersion time can be, for example, but not limited to, any one of 0.1h, 0.2h, 0.3h, 0.4h, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1.0h, or a range between any two of them; the liquid-to-solid ratio of water to solid residue can be, for example, but not limited to, any one of 5 mL / g, 10 mL / g, 15 mL / g, 20 mL / g, 25 mL / g, or a range between any two of them;

[0042] Preferably, the step S4 further includes:

[0043] S5. Add solid aluminum salt to the acidic waste liquid produced in step S3 or the combined waste liquid obtained by mixing the strongly acidic water leaching waste liquid produced in step S4 with the acidic waste liquid produced in step S3, precipitate, and obtain a hydroxyaluminum fluoride product through solid-liquid separation.

[0044] Preferably, in step S1, the particle size of the raw material to be used is ≤0.15 mm. The hazardous waste containing carbon from aluminum electrolysis is carbon slag or waste cathode carbon block.

[0045] Preferably, in step S2, the top of the high-temperature mechanical activation device is equipped with an inlet / exhaust valve having a polytetrafluoroethylene lining.

[0046] Preferably, in step S2, if the raw material to be used is a waste cathode carbon block, an oxidizing gas is introduced to perform decyanation treatment. The oxidizing gas is air, oxygen-enriched gas or carbon dioxide.

[0047] Preferably, in step S3, the liquid reaction agent is one or more of nitric acid, sulfuric acid, and hydrochloric acid. The concentration of the liquid reaction agent is 2 to 12 mol / L, and the liquid-to-solid ratio of the liquid reaction agent to the activated material is 5 to 30 mL / g. Specifically, the concentration of the liquid reaction agent can be, for example, but not limited to, any one of 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, 11 mol / L, 12 mol / L, or a range between any two of them; the liquid-to-solid ratio of the liquid reaction agent to the activated material can be, for example, but not limited to, any one of 5 mL / g, 10 mL / g, 15 mL / g, 20 mL / g, 25 mL / g, 30 mL / g, or a range between any two of them;

[0048] Preferably, in step S4, the solid residue needs to be immersed in water for 3 to 4 times, the pH value of the waste liquid from the first immersion is very small, and the pH value of the waste liquid from the immersion increases successively with the number of immersions, so the waste liquid from the immersion includes strongly acidic waste liquid from the immersion and weakly acidic waste liquid from the immersion, wherein the pH value of the strongly acidic waste liquid from the immersion has a value of ≤2, and is mixed with the acidic waste liquid from step S3 to obtain a combined waste liquid, and the pH value of the weakly acidic waste liquid from the immersion has a value of >2, and is returned to the immersion treatment.

[0049] Preferably, in step S5, solid aluminum salt is added to the acidic waste liquid produced in step S3 or the combined waste liquid obtained by mixing the strongly acidic water immersion waste liquid produced in step S4 with the acidic waste liquid produced in step S3, the pH value is adjusted to 3.5-6.5, the crystallization temperature is 40-90°C, and a precipitate is precipitated. The solid aluminum salt is one or more of aluminum nitrate, aluminum sulfate or aluminum chloride. Specifically, the pH value can be, for example, but not limited to, any one of 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5 or a range between any two; the crystallization temperature can be, for example, but not limited to, any one of 40°C, 50°C, 60°C, 70°C, 80°C, 90°C or a range between any two.

[0050] The technical solution of the present invention is further described below in conjunction with specific embodiments. Example 1

[0051] A method for recycling hazardous carbon-containing waste from aluminum electrolysis, comprising the following steps:

[0052] S1. The waste cathode carbon blocks of aluminum electrolysis are subjected to multi-stage crushing and screening to prepare a stand-by raw material with a particle size of ≤0.15mm;

[0053] S2. The raw material to be used is added to a high-temperature ball mill for high-temperature mechanical activation to obtain an activated material, the ball mill speed is 250 r / min, the activation time is 0.5h, the activation temperature is 240°C, and air is introduced for decyanation treatment;

[0054] S3. After the high-temperature mechanical activation is completed, sulfuric acid solution is added to the high-temperature ball mill for pressurized activation leaching; the air inlet valve and the exhaust valve are closed, the activation speed is 300 r / min, the leaching time is 1.0h, the leaching temperature is 220°C, the concentration of sulfuric acid solution is 6 mol / L, and the liquid-solid ratio of sulfuric acid solution and activated material is 20 mL / g; after the leaching is completed, liquid-solid separation and ball material separation are performed in sequence to obtain acidic waste liquid and solid residue;

[0055] S4. The solid residue is subjected to water leaching treatment to obtain recovered carbon material and water leaching waste liquid; the water leaching temperature is 60°C, the water leaching time is 0.5h, and the liquid-to-solid ratio of water to solid residue is 20 mL / g; the fixed carbon content of the recovered carbon material is 99.24%, and the leaching rate of fluoride is 99.58%; the strongly acidic water leaching waste liquid is mixed with the acidic waste liquid to obtain a combined waste liquid, and the weakly acidic water leaching waste liquid is returned to the water leaching treatment.

[0056] S5. Aluminum sulfate was added to the combined waste liquid, the pH value was adjusted to 5.5, the crystallization temperature was 80°C, a precipitate was precipitated, and after solid-liquid separation, a hydroxyaluminum fluoride product was obtained, and the fluorine recovery rate was 98.82%. Example 2

[0057] A method for recycling hazardous carbon-containing waste from aluminum electrolysis, comprising the following steps:

[0058] S1. The waste cathode carbon blocks of aluminum electrolysis are subjected to multi-stage crushing and screening to prepare a stand-by raw material with a particle size of ≤0.15mm;

[0059] S2. The raw material to be used is added to a high-temperature ball mill for high-temperature mechanical activation to obtain an activated material, the ball mill speed is 200 r / min, the activation time is 1.0h, the activation temperature is 220°C, and oxygen-enriched decyanation is introduced;

[0060] S3. After the high-temperature mechanical activation is completed, a hydrochloric acid solution is added to the high-temperature ball mill for pressurized activation leaching; the air inlet valve and the exhaust valve are closed, the activation speed is 250 r / min, the leaching time is 1.5h, the leaching temperature is 200°C, the concentration of the hydrochloric acid solution is 10 mol / L, and the liquid-solid ratio of the hydrochloric acid solution and the activated material is 25 mL / g. After the leaching is completed, liquid-solid separation and ball material separation are performed in sequence to obtain acidic waste liquid and solid residue;

[0061] S4. The solid residue is subjected to water leaching treatment to obtain recovered carbon material and water leaching waste liquid; the water leaching temperature is 70°C, the water leaching time is 1.0h, and the liquid-to-solid ratio of water to solid residue is 20 mL / g; the fixed carbon content of the recovered carbon material is 99.13%, and the leaching rate of fluoride is 99.39%; the strongly acidic water leaching waste liquid is mixed with the acidic waste liquid to obtain a combined waste liquid, and the weakly acidic water leaching waste liquid is returned to the water leaching treatment.

[0062] S5. Aluminum chloride is added to the combined waste liquid, the pH value is adjusted to 5.75, the crystallization temperature is 60°C, a precipitate is precipitated, and after solid-liquid separation, a hydroxyaluminum fluoride product is obtained, and the fluorine recovery rate is 98.59%. Example 3

[0063] A method for recycling hazardous carbon-containing waste from aluminum electrolysis, comprising the following steps:

[0064] S1. The waste cathode carbon blocks of aluminum electrolysis are subjected to multi-stage crushing and screening to prepare a stand-by raw material with a particle size of ≤0.15mm;

[0065] S2. The raw material to be used is added to a high-temperature ball mill for high-temperature mechanical activation to obtain an activated material, the ball mill speed is 150 r / min, the activation time is 0.5h, the activation temperature is 240°C, and air is introduced for decyanation treatment;

[0066] S3. After the high-temperature mechanical activation is completed, a nitric acid solution is added to the high-temperature ball mill for pressurized activation leaching; the air inlet valve and the exhaust valve are closed, the activation speed is 200 r / min, the leaching time is 1.0h, the leaching temperature is 180°C, the concentration of the nitric acid solution is 8 mol / L, and the liquid-solid ratio of the nitric acid solution and the activated material is 15 mL / g. After the leaching is completed, liquid-solid separation and ball material separation are performed in sequence to obtain acidic waste liquid and solid residue;

[0067] S4. The solid residue is subjected to water leaching treatment to obtain recovered carbon material and water leaching waste liquid; the water leaching temperature is 50°C, the water leaching time is 0.5h, and the liquid-to-solid ratio of water to solid residue is 20 mL / g; the fixed carbon content of the recovered carbon material is 98.65%, and the leaching rate of fluoride is 99.08%; the strongly acidic water leaching waste liquid is mixed with the acidic waste liquid to obtain a combined waste liquid, and the weakly acidic water leaching waste liquid is returned to the water leaching treatment.

[0068] S5. Aluminum nitrate was added to the combined waste liquid, the pH value was adjusted to 6.0, the crystallization temperature was 80°C, a precipitate was precipitated, and after solid-liquid separation, a hydroxyaluminum fluoride product was obtained, and the fluorine recovery rate was 98.26%. Example 4

[0069] A method for recycling hazardous carbon-containing waste from aluminum electrolysis, comprising the following steps:

[0070] S1. The aluminum electrolytic carbon slag is subjected to multi-stage crushing and screening to prepare a stand-by raw material with a particle size of ≤0.15mm;

[0071] S2. The raw materials to be used are added to a high-temperature ball mill for high-temperature mechanical activation to obtain an activated material, the ball mill speed is 250 r / min, the activation time is 1.5h, and the activation temperature is 200°C;

[0072] S3. After the high-temperature mechanical activation is completed, a hydrochloric acid solution is added to the high-temperature ball mill for pressurized activation leaching; the air inlet valve and the exhaust valve are closed, the activation speed is 250 r / min, the leaching time is 1.0h, the leaching temperature is 220°C, the concentration of the hydrochloric acid solution is 8 mol / L, and the liquid-solid ratio of the hydrochloric acid solution and the activated material is 30 mL / g. After the leaching is completed, liquid-solid separation and ball material separation are performed in sequence to obtain acidic waste liquid and solid residue;

[0073] S4. The solid residue is subjected to water leaching treatment to obtain recovered carbon material and water leaching waste liquid; the water leaching temperature is 60°C, the water leaching time is 1.0h, and the liquid-to-solid ratio of water to solid residue is 20 mL / g; the fixed carbon content of the recovered carbon material is 98.88%, and the leaching rate of fluoride is 99.35%; the strongly acidic water leaching waste liquid is mixed with the acidic waste liquid to obtain a combined waste liquid, and the weakly acidic water leaching waste liquid is returned to the water leaching treatment.

[0074] S5. Aluminum chloride is added to the combined waste liquid, the pH value is adjusted to 5.25, the crystallization temperature is 80°C, a precipitate is precipitated, and after solid-liquid separation, a hydroxyaluminum fluoride product is obtained, and the fluorine recovery rate is 98.52%. Example 5

[0075] A method for recycling hazardous carbon-containing waste from aluminum electrolysis, comprising the following steps:

[0076] S1. The aluminum electrolytic carbon slag is subjected to multi-stage crushing and screening to prepare a stand-by raw material with a particle size of ≤0.15mm;

[0077] S2. The raw materials to be used are added to a high-temperature ball mill for high-temperature mechanical activation to obtain an activated material, the ball mill speed is 300 r / min, the activation time is 1.0h, and the activation temperature is 240°C;

[0078] S3. After the high-temperature mechanical activation is completed, sulfuric acid solution is added to the high-temperature ball mill for pressurized activation leaching; the air inlet valve and the exhaust valve are closed, the activation speed is 300 r / min, the leaching time is 2.0h, the leaching temperature is 220°C, the concentration of sulfuric acid solution is 6 mol / L, and the liquid-solid ratio of sulfuric acid solution and activated material is 25 mL / g. After the leaching is completed, liquid-solid separation and ball material separation are performed in sequence to obtain acidic waste liquid and solid residue;

[0079] S4. The solid residue is subjected to water leaching treatment to obtain recovered carbon material and water leaching waste liquid; the water leaching temperature is 60°C, the water leaching time is 0.5h, and the liquid-to-solid ratio of water to solid residue is 20 mL / g; the fixed carbon content of the recovered carbon material is 99.05%, and the leaching rate of fluoride is 99.47%; the strongly acidic water leaching waste liquid is mixed with the acidic waste liquid to obtain a combined waste liquid, and the weakly acidic water leaching waste liquid is returned to the water leaching treatment.

[0080] S5. Aluminum sulfate was added to the combined waste liquid, the pH value was adjusted to 5.5, the crystallization temperature was 90°C, a precipitate was precipitated, and after solid-liquid separation, a hydroxyaluminum fluoride product was obtained, and the fluorine recovery rate was 98.77%. Example 6

[0081] A method for recycling hazardous carbon-containing waste from aluminum electrolysis, comprising the following steps:

[0082] S1. The aluminum electrolytic carbon slag is subjected to multi-stage crushing and screening to prepare a stand-by raw material with a particle size of ≤0.15mm;

[0083] S2. The raw materials to be used are added to a high-temperature ball mill for high-temperature mechanical activation to obtain an activated material, the ball mill speed is 200 r / min, the activation time is 2.0h, and the activation temperature is 240°C;

[0084] S3. After the high-temperature mechanical activation is completed, a nitric acid solution is added to the high-temperature ball mill for pressurized activation leaching; the air inlet valve and the exhaust valve are closed, the activation speed is 200 r / min, the leaching time is 1.0h, the leaching temperature is 180°C, the concentration of the nitric acid solution is 6 mol / L, and the liquid-solid ratio of the nitric acid solution and the activated material is 20 mL / g. After the leaching is completed, liquid-solid separation and ball material separation are performed in sequence to obtain acidic waste liquid and solid residue;

[0085] S4. The solid residue is subjected to water leaching treatment to obtain recovered carbon material and water leaching waste liquid; the water leaching temperature is 60°C, the water leaching time is 1.0h, and the liquid-to-solid ratio of water to solid residue is 20 mL / g; the fixed carbon content of the recovered carbon material is 98.59%, and the leaching rate of fluoride is 99.07%; the strongly acidic water leaching waste liquid is mixed with the acidic waste liquid to obtain a combined waste liquid, and the weakly acidic water leaching waste liquid is returned to the water leaching treatment.

[0086] S5. Aluminum nitrate was added to the combined waste liquid, the pH value was adjusted to 5.0, the crystallization temperature was 60°C, a precipitate was precipitated, and after solid-liquid separation, a hydroxyaluminum fluoride product was obtained, and the fluorine recovery rate was 98.34%.

[0087] The present invention adopts high-temperature mechanical activation to assist in the recovery of carbon materials and fluorine-containing components in aluminum electrolysis carbon-containing hazardous wastes, and uses a high-temperature ball mill to construct a pressurized activation leaching system. On the one hand, the mechanical activation and high-pressure environment can synergistically strengthen the wet leaching process to improve the separation efficiency of carbon materials and fluorine-containing components; on the other hand, compared with the traditional mechanical activation → pressurized leaching, which needs to be completed in different equipment links, the process flow is effectively shortened, equipment investment and site occupation are saved, and the processing efficiency is significantly improved; the leaching toxicity of aluminum electrolysis carbon-containing hazardous wastes is fully utilized to establish a hydrofluoric acid-nitric acid / sulfuric acid / hydrochloric acid mixed leaching system, further improve the impurity removal ability of the reaction system, and the fixed carbon content of the recovered carbon material is ≥98.5%, and the leaching rate of fluoride is ≥99.0%; by adding aluminum salts, pH value and temperature control, hydroxyaluminum fluoride products can be extracted from acidic waste liquids to avoid secondary pollution, and the resource recovery of non-carbon valuable components of aluminum electrolysis carbon-containing hazardous wastes is realized, wherein the recovery rate of fluorine is ≥98.0%.

[0088] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for recycling hazardous carbon-containing waste from aluminum electrolysis, characterized in that: The steps include: S1. Perform multi-stage crushing and screening of hazardous waste containing carbon from aluminum electrolysis to prepare raw materials for use; S2. Add the unused raw materials into a high-temperature ball mill for high-temperature mechanical activation to obtain an activated material, the ball mill speed is 50~350 r / min, the activation time is 0.1~2.0h, and the activation temperature is 100~250℃; S3. After the high-temperature mechanical activation is completed, a liquid reaction agent is added to the high-temperature ball mill for pressurized activation leaching; the activation speed is 100~300 r / min, the leaching time is 0.1~4.0h, the leaching temperature is 120~240°C, and after the leaching is completed, liquid-solid separation and ball material separation are performed in sequence to obtain acidic waste liquid and solid residue; the liquid reaction agent is one or more of nitric acid, sulfuric acid, and hydrochloric acid; S4. The solid residue is subjected to water immersion treatment to obtain recovered carbon material and water immersion waste liquid; the water immersion temperature is 30~80℃, the water immersion time is 0.1~1.0h, and the liquid-to-solid ratio of water to the solid residue is 5~25 mL / g.

2. The processing method according to claim 1, characterized in that: After step S4, the following steps are also included: S5. Adding solid aluminum salt to the acidic waste liquid produced in step S3 to precipitate, and performing solid-liquid separation to obtain a hydroxyaluminum fluoride product.

3. The processing method according to claim 1 or 2, characterized in that: In the step S1, the particle size of the raw material to be used is ≤0.15 mm.

4. The processing method according to claim 1 or 2, characterized in that: In the step S1, the hazardous carbon-containing waste from aluminum electrolysis is carbon slag or waste cathode carbon blocks.

5. The processing method according to claim 1 or 2, characterized in that: In step S2, if the raw material to be used is a waste cathode carbon block, an oxidizing gas is introduced to perform decyanation treatment.

6. The processing method according to claim 5, characterized in that: In step S2, the oxidizing gas is air, oxygen-enriched gas or carbon dioxide.

7. The processing method according to claim 1 or 2, characterized in that: In step S3, the concentration of the liquid reaction agent is 2-12 mol / L, and the liquid-to-solid ratio of the liquid reaction agent to the activation material is 5-30 mL / g.

8. The processing method according to claim 1 or 2, characterized in that: In step S4, the leaching waste liquid includes strongly acidic leaching waste liquid and weakly acidic leaching waste liquid, wherein the strongly acidic leaching waste liquid has a pH value of ≤2 and is mixed with the acidic waste liquid of step S3 to obtain a combined waste liquid, and the weakly acidic leaching waste liquid has a pH value of >2 and is returned to the leaching treatment.

9. The processing method according to claim 2, characterized in that: In the step S5, solid aluminum salt is added to the combined waste liquid, the pH value is adjusted to 3.5-6.5, the crystallization temperature is 40-90° C., and a precipitate is precipitated.

10. The processing method according to claim 2, characterized in that: In step S5, the solid aluminum salt is one or more of aluminum nitrate, aluminum sulfate or aluminum chloride.

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