Harmless treatment system and treatment method for overhaul slag of aluminum electrolysis cell

Abstract

The invention discloses a harmless treatment system and method for overhaul slag of an aluminum electrolysis cell. The harmless treatment system comprises a pretreatment system and a grinding system. The pretreatment system comprises a discharging pit, a plate type feeding machine, a separating machine, a first conveying device and a sorting storeroom. The plate-type feeding machine is arranged at the bottom of the discharging pit and is connected with the separator; the separator is connected with the sorting storehouse through a first conveying device; the grinding system comprises a second conveying device, a crusher, a ball mill and a sedimentation tank; and the sorting storehouse, the second conveying device, the crusher, the ball mill and the settling pond are connected in sequence. The method can effectively solve the problem of safe disposal of dangerous waste residues generated by electrolytic aluminum, so that the dangerous waste residues meet the environmental protection requirement, and the purpose of comprehensive and harmless treatment of the electrolytic aluminum overhaul waste residues is achieved.

Description

Technical Field

[0001] The present invention relates to the field of aluminum electrolysis waste treatment, and more particularly to a harmless treatment system and method for aluminum electrolytic cell overhaul slag. Background Art

[0002] China's electrolytic aluminum production started in the 1950s. After decades of development, electrolytic aluminum technology has made great progress. China's large-scale pre-baked anode electrolytic cell design level and electrolytic aluminum production technology management level have reached the world's advanced level. At present, the electrolytic aluminum industry mainly adopts cryolite-alumina molten salt electrolysis method, using molten cryolite as solvent, alumina as solute, carbonite as anode, and aluminum liquid as cathode. After a strong direct current is passed, an electrochemical reaction is carried out at the two electrodes in the electrolytic cell at 950℃~970℃ to obtain pure aluminum.

[0003] The electrolytic cell is a key equipment in the production of electrolytic aluminum. Since the carbon cathode has good wettability to the electrolyte molten salt, the cathode lining is inevitably corroded by the electrolyte, aluminum liquid, etc., which damages the lining of the electrolytic cell. Therefore, the life of the aluminum electrolytic cell is generally only 2 to 5 years, and regular maintenance and material replacement are required. The replaced overhaul slag is mainly composed of some waste cathode (anode) carbon blocks, refractory materials and anti-permeability materials, including a large amount of cryolite. Cryolite, as a flux for electrolytic aluminum, has important resource recovery value, while fluoride and cyanide have been listed in the list of hazardous solid wastes by the national environmental protection regulatory authorities.

[0004] At present, the electrolytic aluminum industry in my country produces about 250,000 tons of aluminum electrolytic cell overhaul slag each year, and there are more than 2 million tons of accumulated stockpiles. Most aluminum plants have not effectively treated and recycled these overhaul slags, and mainly use open-air stacking or soil landfill after anti-seepage treatment. This not only occupies a large amount of land and causes waste of resources, but also its dust will seriously pollute the atmospheric environment. At the same time, the fluoride and cyanide in the overhaul slag are both water-soluble. If the overhaul slag is discarded at will, the fluoride and cyanide in it will flow into rivers with rainwater, infiltrate into soil and groundwater, and cause serious pollution to the surrounding environment, soil and groundwater.

[0005] In the prior art, there is no shortage of research on pollution prevention and control of overhaul slag of aluminum electrolytic cells. For example, magnetic separation is used to separate iron. Due to the complex composition of overhaul slag, ordinary magnetic separators are not effective, and the equipment investment for gradient magnetic separation or superconducting magnetic separation is huge, with high energy consumption and cost. Another example is the use of pyrolysis for harmless treatment, placing the overhaul slag in a fluidized bed, adding sulfate, and passing oxygen into high-temperature combustion to decompose cyanide. This process involves secondary pollution, and has high requirements on equipment materials and sealing, and high operating costs, making it difficult to promote and use in industry. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a harmless treatment system and method for aluminum electrolytic cell overhaul slag, which can harmlessly and systematically treat electrolytic aluminum waste slag, save production space, save treatment costs, and eliminate the discharge of three wastes.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A harmless treatment system for aluminum electrolytic cell overhaul slag, comprising: a pretreatment system and a grinding system;

[0009] The pre-processing system comprises: a discharge pit, a plate feeder, a separator, a first conveying device and a sorting warehouse;

[0010] The plate feeder is arranged at the bottom of the discharge pit and connected to the separator;

[0011] The separator is connected to the sorting warehouse via a first conveying device;

[0012] The grinding system includes a second conveying device, a crusher, a ball mill and a sedimentation tank;

[0013] The sorting warehouse, the second conveying device, the crusher, the ball mill and the sedimentation tank are connected in sequence.

[0014] Preferably, the above-mentioned processing system further comprises: a dust processing system;

[0015] The dust handling system includes a suction machine and a bag dust collector;

[0016] The separator adopts a dust hood connected to the bag dust collector through a pipeline, and the air outlet of the suction machine is connected to the bag dust collector through a pipeline.

[0017] Preferably, the above-mentioned treatment system further comprises: a flue gas treatment system;

[0018] The flue gas treatment system includes a smoke absorption tower;

[0019] The smoke absorption tower is connected to the ball mill.

[0020] Preferably, the above-mentioned processing system further comprises: a post-processing system;

[0021] The post-processing system comprises: a landfill tank and a filtrate collection tank;

[0022] The sedimentation tank, landfill tank and filtrate collection tank are connected in sequence;

[0023] The filtrate collecting tank is also connected to the ball mill.

[0024] Another object of the present invention is to provide a method for harmless treatment of aluminum electrolytic cell overhaul slag, using the above-mentioned aluminum electrolytic cell overhaul slag harmless treatment system, specifically comprising the following steps:

[0025] (1) The aluminum electrolytic cell overhaul slag is unloaded into the unloading pit, which is set in a sealing device. When unloading, the automatic door of the sealing device is opened, and the vehicle enters. After the unloading is completed, the automatic door is closed; after the unloading is completed, the material enters the separator through the plate feeder, and the separator separates the overhaul slag into blocks. The blocks are sent to the sorting warehouse for sorting through the first conveying device, and the surface is sucked into the bag dust collector;

[0026] (2) steel bars, aluminum slag, silicon carbide bricks, cathode carbon blocks, refractory materials and other usable materials are sorted out, and then leaching tests are performed on the sorted materials. If the materials meet the standards, they are sent to a warehouse for storage. If they do not meet the standards, they are sent to a crusher for crushing through a second conveying device, and then sent to a ball mill for fine grinding. Water and a decyanide agent are then added to the ball mill until the concentration of cyanide is less than 4.5 mg / L. A defluoride agent is then added to the ball mill until the concentration of fluoride is less than 100 mg / L.

[0027] (3) sending the ball-milled material into a sedimentation tank for sedimentation and dehydration to obtain a supernatant and solid waste residue; the supernatant is returned to the ball mill, and a waste residue leaching experiment is performed on the solid waste residue with a moisture content of less than 85%, and the material that meets the hazardous waste landfill standard is sent to a landfill tank for landfilling, and the solid waste residue that does not meet the hazardous waste landfill standard is used as the waste residue to be treated and then continues to be treated in step (2);

[0028] (4) collecting the leachate generated in the landfill pool into a leachate collection pool, and treating the leachate through pH adjustment, precipitation, and separation to obtain supernatant water and aqueous waste residue; the water in the supernatant water that meets the production water standard is directly reused in the fine grinding process of the ball mill in step (2), and the aqueous waste residue with a water content of less than 50% is placed in a landfill pool for landfill treatment.

[0029] Preferably, the silicon carbide brick testing standards in step (2) include:

[0030] Si content ≥ 70%, harmful component CN content < 1.2%. F content < 23%;

[0031] The aluminum slag testing standards include:

[0032] Al content ≥ 40%, harmful component CN content CN < 1%, F content < 21%;

[0033] The cathode carbon brick testing standards include:

[0034] Fixed carbon content ≥43%, harmful component CN content <0.9%, F content <24%.

[0035] The present invention separates and sorts by a separator and detects the sorted products, so as to recycle the valuable products and reduce the process cost.

[0036] Preferably, the crushing in step (2) is crushing to a particle size of less than 8 mm; and the fine grinding is fine grinding to a particle size of less than 0.5 mm.

[0037] Preferably, the cyanide removal agent in step (2) comprises one or more of sodium chlorate, bleaching powder, and bleaching powder essence.

[0038] Preferably, the solid-liquid ratio of water to cyanide removal agent in step (2) is 1:(350-400).

[0039] Preferably, the defluorination agent in step (2) includes one or more of calcium chloride, aluminum chloride, magnesium chloride, calcium hydroxide, and calcium oxide.

[0040] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0041] The waste water generated in the process of the present invention can be recycled and reused, and no waste water is discharged; the waste gas generated is mainly dust-containing air and harmful gas generated when waste residue meets water in the ball mill, which is discharged into the atmosphere after dust removal and harmful gas removal in the acid mist absorption tower, and no waste gas is discharged; the solid waste generated is sent to the landfill for landfill treatment, and no solid waste is discharged;

[0042] The present invention can effectively solve the problem of safe disposal of hazardous waste slag generated by electrolytic aluminum, make it meet environmental protection requirements, and further achieve the purpose of comprehensive and harmless treatment of electrolytic aluminum overhaul waste slag; through a systematic, complete and recyclable treatment method, the hazardous waste generated by electrolytic aluminum is centrally disposed of, effectively reducing the cost of hazardous waste treatment and disposal of the enterprise, and reducing the space occupied by hazardous waste storage, bringing good economic benefits to the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] 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 embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0044] Figure 1 It is a system structure diagram of the present invention;

[0045] Among them, in the figure:

[0046] 1-unloading pit; 2-plate feeder; 3-separator; 4-first conveying device; 5-sorting warehouse; 6-second conveying device; 7-crusher; 8-ball mill; 9-sedimentation tank; 10-dust hood; 11-bag dust collector; 12-suction machine; 13-smoke absorption tower; 14-landfill pool; 15-filtrate collection pool. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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.

[0048] Example 1

[0049] This embodiment provides a harmless treatment system for aluminum electrolytic cell overhaul slag, including: a pretreatment system, a grinding system, a dust treatment system, a flue gas treatment system and a post-treatment system;

[0050] The pre-processing system includes: a discharge pit 1, a plate feeder 2, a separator 3, a first conveying device 4 and a sorting warehouse 5;

[0051] The plate feeder 2 is arranged at the bottom of the discharge pit 1 and connected to the separator 3;

[0052] The separator 3 is connected to the sorting warehouse 5 via the first conveying device 4;

[0053] The grinding system includes a second conveying device 6, a crusher 7, a ball mill 8 and a sedimentation tank 9;

[0054] The sorting warehouse 5, the second conveying device 6, the crusher 7, the ball mill 8 and the sedimentation tank 9 are connected in sequence.

[0055] The dust handling system includes a suction machine 12 and a bag dust collector 11;

[0056] The separator 3 adopts a dust hood 10 connected to the bag dust collector 11 through a pipeline, and the air outlet of the suction machine 12 is connected to the bag dust collector 11 through a pipeline.

[0057] The flue gas treatment system includes a smoke absorption tower 13;

[0058] The smoke absorption tower 13 is connected to the ball mill 8 .

[0059] The post-treatment system includes: a landfill pool 14 and a filtrate collection pool 15;

[0060] The sedimentation tank 13, the landfill tank 14 and the filtrate collection tank 15 are connected in sequence;

[0061] The filtrate collecting tank 15 is also connected to the ball mill 8 .

[0062] Example 2

[0063] This embodiment provides a method for harmless treatment of aluminum electrolytic cell overhaul slag, using the above-mentioned aluminum electrolytic cell overhaul slag harmless treatment system, specifically comprising the following steps:

[0064] (1) The aluminum electrolytic cell overhaul slag is unloaded into the unloading pit 1. The unloading pit 1 is set in a sealing device. When unloading, the automatic door of the sealing device is opened, and the vehicle enters. After the unloading is completed, the automatic door is closed; after the unloading is completed, the material enters the separator 3 through the plate feeder 2, and the separator 3 separates the overhaul slag into blocks. The blocks are sent to the sorting warehouse 5 for sorting through the first conveying device, and the material is sucked into the bag dust collector 11;

[0065] (2) steel bars, aluminum slag, silicon carbide bricks, cathode carbon blocks, refractory materials and other usable materials are sorted out, and then a leaching test is performed on the sorted materials. If the materials meet the standards, they are sent to a warehouse for storage. If they do not meet the standards, they are sent to a crusher 7 through a second conveying device 6 for crushing to a particle size of less than 8 mm, and then sent to a ball mill 8 for fine grinding to a particle size of less than 0.5 mm. Water and sodium chlorate are then added to the ball mill 8, with a solid-liquid ratio of water to sodium chlorate of 1:400, until the concentration of cyanide is less than 4.5 mg / L, and aluminum chlorate is then added to the ball mill 8 until the concentration of fluoride is less than 100 mg / L;

[0066] (3) The ball-milled material is sent to a sedimentation tank 9 for sedimentation and dehydration to obtain a supernatant and solid waste residue; the supernatant is reused in the ball mill 8, and a waste residue leaching experiment is performed on the solid waste residue with a water content of less than 85%, and the material that meets the hazardous waste landfill standard is sent to a landfill tank 14 for landfilling, and the solid waste residue that does not meet the hazardous waste landfill standard is used as the waste residue to be treated and then continues to be treated in step (2);

[0067] (4) The leachate generated in the landfill pool 14 is collected into a leachate collection pool, and the leachate is treated by pH adjustment, precipitation, and separation to obtain supernatant water and water-containing waste residue; the water in the supernatant water that meets the production water standard is directly reused in the fine grinding process of the ball mill 8 in step (2), and the water-containing waste residue with a water content of less than 50% is placed in the landfill pool 14 for landfill treatment.

[0068] In this embodiment, the silicon carbide brick inspection standards in step (2) include:

[0069] Si content ≥ 70%, harmful component CN content < 1.2%. F content < 23%;

[0070] The aluminum slag testing standards include:

[0071] Al content ≥ 40%, harmful component CN content CN < 1%, F content < 21%;

[0072] The cathode carbon brick testing standards include:

[0073] Fixed carbon content ≥43%, harmful component CN content <0.9%, F content <24%.

[0074] Example 3

[0075] This embodiment provides a method for harmless treatment of aluminum electrolytic cell overhaul slag, using the above-mentioned aluminum electrolytic cell overhaul slag harmless treatment system, specifically comprising the following steps:

[0076] (1) The aluminum electrolytic cell overhaul slag is unloaded into the unloading pit 1. The unloading pit 1 is set in a sealing device. When unloading, the automatic door of the sealing device is opened, and the vehicle enters. After the unloading is completed, the automatic door is closed; after the unloading is completed, the material enters the separator 3 through the plate feeder 2, and the separator 3 separates the overhaul slag into blocks. The blocks are sent to the sorting warehouse 5 for sorting through the first conveying device, and the material is sucked into the bag dust collector 11;

[0077] (2) steel bars, aluminum slag, silicon carbide bricks, cathode carbon blocks, refractory materials and other usable materials are sorted out, and then a leaching test is performed on the sorted materials. If the materials meet the standards, they are sent to a warehouse for storage. If they do not meet the standards, they are sent to a crusher 7 through a second conveying device 6 for crushing to a particle size of less than 8 mm, and then sent to a ball mill 8 for fine grinding to a particle size of less than 0.5 mm. Water and bleaching powder are then added to the ball mill 8, with a solid-liquid ratio of 1:370, until the concentration of cyanide is less than 4.5 mg / L, and magnesium chloride is then added to the ball mill 8 until the concentration of fluoride is less than 100 mg / L;

[0078] (3) The ball-milled material is sent to a sedimentation tank 9 for sedimentation and dehydration to obtain a supernatant and solid waste residue; the supernatant is reused in the ball mill 8, and a waste residue leaching experiment is performed on the solid waste residue with a water content of less than 85%, and the material that meets the hazardous waste landfill standard is sent to a landfill tank 14 for landfilling, and the solid waste residue that does not meet the hazardous waste landfill standard is used as the waste residue to be treated and then continues to be treated in step (2);

[0079] (4) The leachate generated in the landfill pool 14 is collected into a leachate collection pool, and the leachate is treated by pH adjustment, precipitation, and separation to obtain supernatant water and water-containing waste residue; the water in the supernatant water that meets the production water standard is directly reused in the fine grinding process of the ball mill 8 in step (2), and the water-containing waste residue with a water content of less than 50% is placed in the landfill pool 14 for landfill treatment.

[0080] In this embodiment, the silicon carbide brick inspection standards in step (2) include:

[0081] Si content ≥ 70%, harmful component CN content < 1.2%. F content < 23%;

[0082] The aluminum slag testing standards include:

[0083] Al content ≥ 40%, harmful component CN content CN < 1%, F content < 21%;

[0084] The cathode carbon brick testing standards include:

[0085] Fixed carbon content ≥43%, harmful component CN content <0.9%, F content <24%.

[0086] Example 4

[0087] This embodiment provides a method for harmless treatment of aluminum electrolytic cell overhaul slag, using the above-mentioned aluminum electrolytic cell overhaul slag harmless treatment system, specifically comprising the following steps:

[0088] (1) The aluminum electrolytic cell overhaul slag is unloaded into the unloading pit 1. The unloading pit 1 is set in a sealing device. When unloading, the automatic door of the sealing device is opened, and the vehicle enters. After the unloading is completed, the automatic door is closed; after the unloading is completed, the material enters the separator 3 through the plate feeder 2, and the separator 3 separates the overhaul slag into blocks. The blocks are sent to the sorting warehouse 5 for sorting through the first conveying device, and the material is sucked into the bag dust collector 11;

[0089] (2) steel bars, aluminum slag, silicon carbide bricks, cathode carbon blocks, refractory materials and other usable materials are sorted out, and then a leaching test is performed on the sorted materials. If the materials meet the standards, they are sent to a warehouse for storage. If they do not meet the standards, they are sent to a crusher 7 through a second conveying device 6 for crushing to a particle size of less than 8 mm, and then sent to a ball mill 8 for fine grinding to a particle size of less than 0.5 mm. Water and bleaching powder are then added to the ball mill 8, with a solid-liquid ratio of 1:350, until the concentration of cyanide is less than 4.5 mg / L, and then calcium chloride is added to the ball mill 8 until the concentration of fluoride is less than 100 mg / L;

[0090] (3) The ball-milled material is sent to a sedimentation tank 9 for sedimentation and dehydration to obtain a supernatant and solid waste residue; the supernatant is reused in the ball mill 8, and a waste residue leaching experiment is performed on the solid waste residue with a water content of less than 85%, and the material that meets the hazardous waste landfill standard is sent to a landfill tank 14 for landfilling, and the solid waste residue that does not meet the hazardous waste landfill standard is used as the waste residue to be treated and then continues to be treated in step (2);

[0091] (4) The leachate generated in the landfill pool 14 is collected into a leachate collection pool, and the leachate is treated by pH adjustment, precipitation, and separation to obtain supernatant water and water-containing waste residue; the water in the supernatant water that meets the production water standard is directly reused in the fine grinding process of the ball mill 8 in step (2), and the water-containing waste residue with a water content of less than 50% is placed in the landfill pool 14 for landfill treatment.

[0092] In this embodiment, the silicon carbide brick inspection standards in step (2) include:

[0093] Si content ≥ 70%, harmful component CN content < 1.2%. F content < 23%;

[0094] The aluminum slag testing standards include:

[0095] Al content ≥ 40%, harmful component CN content CN < 1%, F content < 21%;

[0096] The cathode carbon brick testing standards include:

[0097] Fixed carbon content ≥43%, harmful component CN content <0.9%, F content <24%.

[0098] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0099] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A harmless treatment system for overhaul slag of aluminum electrolytic cell, characterized in that: include: Pretreatment system and grinding system; The pre-processing system comprises: a discharge pit, a plate feeder, a separator, a first conveying device and a sorting warehouse; The plate feeder is arranged at the bottom of the discharge pit and connected to the separator; The separator is connected to the sorting warehouse via a first conveying device; The grinding system includes a second conveying device, a crusher, a ball mill and a sedimentation tank; The sorting warehouse, the second conveying device, the crusher, the ball mill and the sedimentation tank are connected in sequence.

2. The harmless treatment system for overhaul slag of aluminum electrolytic cell according to claim 1 is characterized in that: Also includes: Dust handling system; The dust handling system includes a suction machine and a bag dust collector; The separator adopts a dust hood connected to the bag dust collector through a pipeline, and the air outlet of the suction machine is connected to the bag dust collector through a pipeline.

3. The harmless treatment system for overhaul slag of aluminum electrolytic cell according to claim 2 is characterized in that: Also includes: Flue gas treatment systems; The flue gas treatment system includes a smoke absorption tower; The smoke absorption tower is connected to the ball mill.

4. The harmless treatment system for overhaul slag of aluminum electrolytic cell according to claim 3 is characterized in that: Also includes: Aftertreatment system; The post-processing system comprises: a landfill tank and a filtrate collection tank; The sedimentation tank, landfill tank and filtrate collection tank are connected in sequence; The filtrate collecting tank is also connected to the ball mill.

5. A method for harmless treatment of aluminum electrolytic cell overhaul slag, characterized in that: The harmless treatment system for overhaul slag of aluminum electrolytic cell according to claim 4 specifically comprises the following steps: (1) The aluminum electrolytic cell overhaul slag is unloaded into the unloading pit, which is set in a sealing device. When unloading, the automatic door of the sealing device is opened, and the vehicle enters. After the unloading is completed, the automatic door is closed; after the unloading is completed, the material enters the separator through the plate feeder, and the separator separates the overhaul slag into blocks. The blocks are sent to the sorting warehouse for sorting through the first conveying device, and the surface is sucked into the bag dust collector; (2) steel bars, aluminum slag, silicon carbide bricks, cathode carbon blocks, refractory materials and other usable materials are sorted out, and then leaching tests are performed on the sorted materials. If the materials meet the standards, they are sent to a warehouse for storage. If they do not meet the standards, they are sent to a crusher for crushing through a second conveying device, and then sent to a ball mill for fine grinding. Water and a decyanide agent are then added to the ball mill until the concentration of cyanide is less than 4.5 mg / L. A defluoride agent is then added to the ball mill until the concentration of fluoride is less than 100 mg / L. (3) sending the ball-milled material into a sedimentation tank for sedimentation and dehydration to obtain a supernatant and solid waste residue; the supernatant is returned to the ball mill, and a waste residue leaching experiment is performed on the solid waste residue with a moisture content of less than 85%, and the material that meets the hazardous waste landfill standard is sent to a landfill tank for landfilling, and the solid waste residue that does not meet the hazardous waste landfill standard is used as the waste residue to be treated and then continues to be treated in step (2); (4) collecting the leachate generated in the landfill pool into a leachate collection pool, and treating the leachate through pH adjustment, precipitation, and separation to obtain supernatant water and aqueous waste residue; the water in the supernatant water that meets the production water standard is directly reused in the fine grinding process of the ball mill in step (2), and the aqueous waste residue with a water content of less than 50% is placed in a landfill pool for landfill treatment.

6. A method for harmless treatment of aluminum electrolysis cell overhaul slag according to claim 5, characterized in that: The silicon carbide brick testing standards described in step (2) include: Si content ≥ 70%, harmful component CN content < 1.2%. F content < 23%; The aluminum slag testing standards include: Al content ≥ 40%, harmful component CN content CN < 1%, F content < 21%; The cathode carbon brick testing standards include: Fixed carbon content ≥43%, harmful component CN content <0.9%, F content <24%.

7. The method for harmless treatment of aluminum electrolysis cell overhaul slag according to claim 5, characterized in that: The crushing in step (2) is crushing to a particle size of less than 8 mm; the fine grinding is fine grinding to a particle size of less than 0.5 mm.

8. The method for harmless treatment of aluminum electrolysis cell overhaul slag according to claim 5, characterized in that: The cyanide removal agent in step (2) includes one or more of sodium chlorate, bleaching powder and bleaching powder essence.

9. The method for harmless treatment of aluminum electrolysis cell overhaul slag according to claim 5, characterized in that: The solid-liquid ratio of water to cyanide removal agent in step (2) is 1:(350-400).

10. The method for harmless treatment of aluminum electrolytic cell overhaul slag according to claim 5, characterized in that: The defluoridating agent in step (2) includes one or more of calcium chloride, aluminum chloride, magnesium chloride, calcium hydroxide and calcium oxide.

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