CN115849945A - Treatment process of aluminum electrolysis cell overhaul slag - Google Patents
Treatment process of aluminum electrolysis cell overhaul slag Download PDFInfo
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- CN115849945A CN115849945A CN202211270685.2A CN202211270685A CN115849945A CN 115849945 A CN115849945 A CN 115849945A CN 202211270685 A CN202211270685 A CN 202211270685A CN 115849945 A CN115849945 A CN 115849945A
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- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 65
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 60
- 238000000034 method Methods 0.000 title claims abstract description 44
- 239000002893 slag Substances 0.000 title claims abstract description 35
- 238000005868 electrolysis reaction Methods 0.000 title claims description 16
- 239000000919 ceramic Substances 0.000 claims abstract description 101
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 57
- 239000002699 waste material Substances 0.000 claims abstract description 49
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 claims abstract description 42
- 238000010438 heat treatment Methods 0.000 claims abstract description 28
- 239000000843 powder Substances 0.000 claims abstract description 25
- 235000013024 sodium fluoride Nutrition 0.000 claims abstract description 21
- 239000011775 sodium fluoride Substances 0.000 claims abstract description 21
- KXZJHVJKXJLBKO-UHFFFAOYSA-N chembl1408157 Chemical compound N=1C2=CC=CC=C2C(C(=O)O)=CC=1C1=CC=C(O)C=C1 KXZJHVJKXJLBKO-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000001354 calcination Methods 0.000 claims abstract description 16
- 238000004321 preservation Methods 0.000 claims abstract description 16
- 239000002002 slurry Substances 0.000 claims abstract description 16
- 238000000498 ball milling Methods 0.000 claims abstract description 14
- 239000012298 atmosphere Substances 0.000 claims abstract description 13
- 239000004372 Polyvinyl alcohol Substances 0.000 claims abstract description 9
- 229920002451 polyvinyl alcohol Polymers 0.000 claims abstract description 9
- 238000002156 mixing Methods 0.000 claims abstract description 6
- 239000000203 mixture Substances 0.000 claims abstract description 6
- 238000001816 cooling Methods 0.000 claims abstract description 5
- 230000003647 oxidation Effects 0.000 claims abstract description 5
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 5
- 229910052799 carbon Inorganic materials 0.000 claims description 27
- 239000000463 material Substances 0.000 claims description 22
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 20
- 229910052710 silicon Inorganic materials 0.000 claims description 20
- 239000010703 silicon Substances 0.000 claims description 20
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 17
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 13
- 239000011449 brick Substances 0.000 claims description 11
- 238000000746 purification Methods 0.000 claims description 10
- 239000002994 raw material Substances 0.000 claims description 7
- 239000007788 liquid Substances 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 6
- 238000004061 bleaching Methods 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 4
- 239000012300 argon atmosphere Substances 0.000 claims description 3
- 238000004064 recycling Methods 0.000 abstract description 7
- 238000002309 gasification Methods 0.000 abstract description 3
- 238000002360 preparation method Methods 0.000 abstract description 3
- 238000003912 environmental pollution Methods 0.000 description 8
- 239000002910 solid waste Substances 0.000 description 8
- 238000005245 sintering Methods 0.000 description 7
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical compound [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 5
- 239000002920 hazardous waste Substances 0.000 description 4
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 229910010271 silicon carbide Inorganic materials 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 239000003575 carbonaceous material Substances 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000003837 high-temperature calcination Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/60—Production of ceramic materials or ceramic elements, e.g. substitution of clay or shale by alternative raw materials, e.g. ashes
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Abstract
The invention discloses a treatment process of overhaul slag of an aluminum electrolytic cell, which comprises the following steps: sorting overhaul residues of an aluminum electrolytic cell to obtain carbonaceous waste and refractory waste, respectively crushing and ball-milling to obtain carbon powder and ceramic powder, mixing the carbon powder and the ceramic powder in proportion, adding the mixture into a polyvinyl alcohol solution, and ball-milling to obtain slurry; injecting the slurry into a mold, curing and demolding to obtain a ceramic blank; heating the ceramic blank to 1500-1600 ℃ from room temperature in an inert atmosphere at normal pressure, and removing sodium cyanide in the ceramic blank through gasification; heating to 1700-2100 ℃, and removing sodium fluoride in the ceramic blank by gasification; then cooling to room temperature to obtain a ceramic intermediate; and (3) heating the ceramic intermediate to 600-800 ℃ from room temperature in an air atmosphere at normal pressure, carrying out heat preservation calcination for 3-5 h, and removing carbon powder through oxidation to obtain the porous ceramic. The preparation process is simple, changes waste into valuable, and realizes economic and pollution-free recycling of the aluminum electrolytic cell overhaul slag.
Description
Technical Field
The invention relates to the technical field of electrolytic aluminum, in particular to a treatment process of overhaul residues of an aluminum electrolytic cell.
Background
In the production process of electrolytic aluminum, the lining structure of the electrolytic cell is deformed and broken due to the infiltration and corrosion of molten high-temperature electrolyte, and aluminum liquid and electrolyte in the electrolytic cell leak into the bottom of the electrolytic cell from cracks, so that the electrolytic cell cannot be normally used. Therefore, the aluminum electrolysis cell needs to be overhauled on average every 2~5 years, and the cathode lining material removed in the process is called overhaul Sludge (SPL).
The amount of fluoride in the SPL leachate is about 3500mg/L, and the amount of cyanide is about 1mg/L, which exceeds the limit value specified in the standard and is defined as hazardous waste by the national hazardous waste record. The SPL, whether stored or buried, requires significant capital and operating management costs, and presents long-term potential pollution concerns. The SPL mainly comprises cathode carbon blocks, refractory bricks, cathode paste, impermeable materials, casting materials and other components, and all the components are treated as hazardous wastes to cause resource waste.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a treatment process of overhaul residues of an aluminum electrolysis cell, which recycles carbon waste and refractory waste and is used for preparing silicon carbide-silicon nitride porous ceramics, sodium cyanide and sodium fluoride are gasified and absorbed in the process of sintering the ceramics, so that the harmless treatment of the overhaul residues of the aluminum electrolysis cell is realized, the environmental pollution is reduced, and the problems of environmental pollution caused by the solid wastes of the overhaul residues in the aluminum electrolysis industry and the economic value caused by the reutilization of the solid wastes are solved.
The technical scheme adopted by the invention is as follows:
a treatment process of overhaul slag of an aluminum electrolytic cell comprises the following steps:
s1, sorting overhaul residues of the aluminum electrolytic cell to respectively obtain carbon waste and refractory waste;
s2, respectively crushing and ball-milling the carbon waste and the refractory waste to obtain carbon powder and ceramic powder;
s3, mixing the carbon powder and the ceramic powder according to a proportion, adding the mixture into a polyvinyl alcohol solution, and carrying out ball milling to obtain slurry; injecting the slurry into a mold, curing and demolding to obtain a ceramic blank;
s4, heating the ceramic blank to 1500-1600 ℃ from room temperature in an inert atmosphere under normal pressure, carrying out heat preservation calcination for 1-2h, gasifying sodium cyanide in the ceramic blank, and allowing the gasified sodium cyanide to enter a purification system to be absorbed by bleaching liquid; heating to 1700-2100 ℃, calcining for 1-5h under heat preservation, gasifying sodium fluoride in the ceramic blank, allowing the gasified sodium fluoride to enter a purification system, absorbing the gasified sodium fluoride by activated alumina, and cooling to room temperature to obtain a ceramic intermediate;
and S5, heating the ceramic intermediate to 600-800 ℃ from room temperature in an air atmosphere at normal pressure, carrying out heat preservation calcination for 3-5 hours, and removing carbon powder through oxidation to obtain the porous ceramic.
In the treatment process of the overhaul slag of the aluminum electrolytic cell disclosed by the application, in the step S1, the carbonaceous waste is a cathode carbon block or/and a special-shaped carbon block.
In the treatment process of the overhaul slag of the aluminum electrolytic cell disclosed by the application, in the step S1, the refractory waste is one or more of insulating bricks, refractory bricks, impermeable materials and castable materials made of silicon carbide-silicon nitride materials.
In the treatment process of the overhaul slag of the aluminum electrolytic cell disclosed by the application, in the step S2, the particle sizes of the carbon powder and the ceramic powder are 0.5-5 mu m.
In the treatment process of the overhaul slag of the aluminum electrolytic cell disclosed by the application, in the step S3, the carbon powder and the ceramic powder are mixed in proportion, added into a polyvinyl alcohol solution with the mass fraction of 1~5%, and subjected to ball milling for 3 to 10h to obtain slurry.
In the treatment process of the overhaul slag of the aluminum electrolytic cell disclosed by the application, the carbon powder and the ceramic powder are mixed according to the mass ratio of 1-10.
In the treatment process of the overhaul slag of the aluminum electrolytic cell, disclosed by the application, in the step S3, slurry is injected into a mold, the curing is carried out for 5 to 8 hours at the temperature of 60 ℃, and the mold is removed to obtain a ceramic blank.
In the treatment process of the overhaul slag of the aluminum electrolytic cell disclosed by the application, in the step S4, the inert atmosphere is a nitrogen atmosphere or an argon atmosphere.
In the treatment process of the overhaul slag of the aluminum electrolytic cell disclosed by the application, in the step S4, the temperature is increased from the room temperature to 1500-1600 ℃, and the temperature increase rate is 20-30 ℃/min; then heating to 1700 to 2100 ℃, wherein the heating rate is 5 to 10 ℃/min.
In the treatment process of the overhaul slag of the aluminum electrolytic cell disclosed by the application, in the step S5, the temperature is increased from the room temperature to 600-800 ℃, and the temperature increase rate is 20-30 ℃/min.
Compared with the prior art, the invention has the beneficial effects that:
the application provides a treatment process of aluminum cell overhaul residues, which recycles carbon waste and refractory waste of the aluminum cell overhaul residues for preparing silicon carbide-silicon nitride porous ceramics, gasifies and absorbs sodium cyanide and sodium fluoride in the process of sintering the ceramics, realizes harmless treatment of the aluminum cell overhaul residues, reduces environmental pollution, and solves the problems of environmental pollution and economic value reuse of solid waste of the overhaul residues in the aluminum electrolysis industry. The porous ceramic is prepared from the overhaul residues of the aluminum electrolytic cell, the preparation process is simple, the high-value silicon carbide-silicon nitride porous ceramic can be obtained, the recycling value of the overhaul residues of the aluminum electrolytic cell is improved, the waste is changed into valuable, and the economic and pollution-free recycling of the overhaul residues of the aluminum electrolytic cell is realized.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic flow chart of a treatment process of aluminum electrolysis cell overhaul slag.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the application and are not limiting of the application. It should be further noted that, for the convenience of description, only some of the structures related to the present application are shown in the drawings, not all of the structures. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The terms "comprising" and "having," and any variations thereof, in this application are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the specification. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein may be combined with other embodiments.
Referring to fig. 1, an embodiment of the present application provides a treatment process for aluminum cell overhaul residues, and mainly aims to solve the problem of resource waste and the like caused by the existing treatment process of taking all the aluminum cell overhaul residues as hazardous wastes.
The application discloses a treatment process of overhaul slag of an aluminum electrolytic cell, which comprises the following steps:
s1, sorting overhaul residues of the aluminum electrolytic cell to respectively obtain carbon waste and refractory waste;
step S2, respectively crushing and ball-milling the carbon waste and the refractory waste to obtain carbon powder and ceramic powder;
s3, mixing the carbon powder and the ceramic powder according to a proportion, adding the mixture into a polyvinyl alcohol solution, and carrying out ball milling to obtain slurry; injecting the slurry into a mold, curing, and demolding to obtain a ceramic blank;
s4, heating the ceramic blank to 1500-1600 ℃ from room temperature in an inert atmosphere under normal pressure, carrying out heat preservation calcination for 1-2h, gasifying sodium cyanide in the ceramic blank, and allowing the gasified sodium cyanide to enter a purification system to be absorbed by bleaching liquid; heating to 1700-2100 ℃, calcining for 1-5h under heat preservation, gasifying sodium fluoride in the ceramic blank, allowing the gasified sodium fluoride to enter a purification system to be absorbed by activated alumina to form fluorine-carrying alumina, and then taking the fluorine-carrying alumina as a raw material to enter aluminum electrolysis production again; then cooling to room temperature to obtain a ceramic intermediate;
and S5, heating the ceramic intermediate to 600-800 ℃ from room temperature in an air atmosphere at normal pressure, carrying out heat preservation calcination for 3-5 hours, and removing carbon powder through oxidation to obtain the porous ceramic.
The method sorts the overhaul slag of the aluminum electrolytic cell to select the carbonaceous waste and the refractory waste. The refractory waste is mainly silicon nitride-silicon carbide material and can be used as ceramic raw material for preparing ceramic products. The carbon waste is mainly carbon material, and is mixed with ceramic raw material to prepare ceramic product, which can be used as pore-forming agent and sintering aid. The silicon carbide-silicon nitride material is high in price, if the silicon carbide-silicon nitride material is simply separated and recycled, the recycling value is not high, and the silicon carbide-silicon nitride porous ceramic is prepared by mixing the silicon carbide-silicon nitride material with a carbon material, so that the economic value is improved.
Because the overhaul slag of the aluminum electrolytic cell contains a certain amount of sodium fluoride and sodium cyanide, the overhaul slag is prepared into a ceramic product, after water immersion, the fluoride and the cyanide are dissolved out, and if the overhaul slag penetrates underground, the land and the underground water can be polluted. Considering that the boiling point of sodium cyanide is 1496 ℃ and the boiling point of sodium fluoride is 1700 ℃, when the ceramic blank is sintered, the sintering temperature is firstly increased to 1500-1600 ℃, the ceramic blank is subjected to heat preservation and calcination for 1-2h, and the sodium cyanide in the ceramic blank is gasified and enters a purification system to be absorbed by bleaching liquid; and then heating to 1700-2100 ℃, carrying out heat preservation calcination for 1-5h, gasifying sodium fluoride in the ceramic blank, allowing the gasified sodium fluoride to enter a purification system to be absorbed by activated alumina to form fluorine-carrying alumina, and then taking the fluorine-carrying alumina as a raw material to enter aluminum electrolysis production again. Meanwhile, in the gasification process of sodium fluoride and sodium cyanide, pores are formed on the ceramic blank, so that the porosity of the porous ceramic can be improved.
Removing sodium cyanide and sodium fluoride from the ceramic blank to obtain a ceramic intermediate, heating the ceramic intermediate to 600-800 ℃ in an air atmosphere at normal pressure, calcining for 3-5 hours under heat preservation, and oxidizing to remove carbon powder to obtain porous ceramic, so that the porosity of the ceramic is improved to a design level.
The application recycles the carbonaceous waste and the refractory waste of the overhaul residues of the aluminum electrolytic cell for preparing the silicon carbide-silicon nitride porous ceramic, and the sodium cyanide and the sodium fluoride are gasified and absorbed in the process of sintering the ceramic, so that the harmless treatment of the overhaul residues of the aluminum electrolytic cell is realized, the environmental pollution is reduced, and the problems of environmental pollution caused by the solid waste of the overhaul residues in the aluminum electrolysis industry and the economic value caused by the reuse of the solid waste are solved. The porous ceramic is prepared from the overhaul residues of the aluminum electrolytic cell, the preparation process is simple, the high-value silicon carbide-silicon nitride porous ceramic can be obtained, the recycling value of the overhaul residues of the aluminum electrolytic cell is improved, the waste is changed into valuable, and the economic and pollution-free recycling of the overhaul residues of the aluminum electrolytic cell is realized.
In one embodiment, in step S1, the carbonaceous waste is a cathode carbon block or/and a shaped carbon block. The cathode carbon block and the special-shaped carbon block are main components of the overhaul slag of the aluminum electrolysis cell, and are recycled as pore-forming agents and sintering aids for preparing porous ceramics, so that the problem of economic value caused by reutilization of solid waste of the overhaul slag in the aluminum electrolysis industry is solved.
In one embodiment, in step S1, the refractory waste is one or more of insulating brick, refractory brick, impermeable material and casting material made of silicon carbide-silicon nitride material. The main materials of the insulating brick, the refractory brick, the impermeable material and the castable are silicon nitride-silicon carbide, the silicon carbide-silicon nitride material is high in price, if the silicon carbide-silicon nitride material is simply separated and recycled, the recycling value is low, and the silicon carbide-silicon nitride porous ceramic is used for preparing silicon carbide-silicon nitride porous ceramics, is applied to the sewage treatment industry and improves the economic value.
In one embodiment, in step S2, the particle sizes of the carbon powder and the ceramic powder are 0.5 to 5 μm. Specifically, the particle diameters of the carbon powder and the ceramic powder may be 0.5. Mu.m, 1. Mu.m, 2. Mu.m, 3. Mu.m, 4. Mu.m, 5 μm, or the like. And respectively crushing and ball-milling the carbon waste and the refractory waste to obtain carbon powder and ceramic powder with small particle sizes, so that a ceramic blank can be conveniently prepared.
In one embodiment, in step S3, the carbon powder and the ceramic powder are mixed in proportion, added into a solution of 1~5% polyvinyl alcohol, and ball-milled for 3 to 10h to obtain a slurry. The application selects separately carbonaceous waste material, refractory waste material, and the subdividing is broken respectively, and the ball-milling obtains carbon powder and ceramic powder, is convenient for mix carbon powder and ceramic powder of different proportions, prepares the porous ceramic product of different porosities.
Specifically, the mass fraction of the polyvinyl alcohol solution may be 1%, 2%, 3%, 4%, 5%, or the like, preferably 3%. Specifically, the ball milling time may be 3h, 5h, 8h, 10h, etc., preferably 8h.
In one embodiment, the carbon powder and the ceramic powder are mixed in a mass ratio of 1 to 10. Specifically, the mass ratio of the carbon powder to the ceramic powder may be 1.
In one embodiment, in step S3, the slurry is injected into a mold, cured at 60 ℃ for 5 to 8h, and demolded to obtain a ceramic blank.
In one embodiment, in step S4, the inert atmosphere is a nitrogen atmosphere or an argon atmosphere.
In one embodiment, in the step S4, the temperature is raised from the room temperature to 1500 to 1600 ℃, and the heating rate is 20 to 30 ℃/min; then heating to 1700 to 2100 ℃, wherein the heating rate is 5 to 10 ℃/min.
In one embodiment, in the step S5, the temperature is raised from room temperature to 600 to 800 ℃, and the heating rate is 20 to 30 ℃/min.
In a specific implementation scene, the overhaul slag of the aluminum electrolytic cell is sorted, a cathode carbon block and a special-shaped carbon block are selected as carbon waste, insulating bricks, refractory bricks, impermeable materials and castable materials with the components of silicon nitride-silicon carbide are selected as refractory waste, the carbon waste and the refractory waste are respectively crushed and ball-milled to obtain carbon powder and ceramic powder with the particle size of 0.5 to 5 mu m. Mixing carbon powder and ceramic powder according to the mass ratio of 5 to 100, adding the mixture into a 3% polyvinyl alcohol solution, carrying out ball milling for 8 hours to obtain slurry, injecting the slurry into a mold, curing, and demolding to obtain a ceramic blank. Heating the ceramic blank from room temperature to 1500-1600 ℃ at the heating rate of 25 ℃/min in a nitrogen atmosphere under normal pressure, carrying out heat preservation and calcination for 2h, gasifying sodium cyanide in the ceramic blank, and allowing the gasified sodium cyanide to enter a purification system to be absorbed by bleaching liquid; heating to 1700-2100 ℃ at the heating rate of 10 ℃/min, carrying out heat preservation and calcination for 3h, gasifying sodium fluoride in the ceramic blank, allowing the gasified sodium fluoride to enter a purification system, absorbing the gasified sodium fluoride by activated alumina to form fluorine-carrying alumina, and then taking the fluorine-carrying alumina as a raw material to enter aluminum electrolysis production again; and then cooling to room temperature to obtain the ceramic intermediate. And (3) heating the ceramic intermediate to 600-800 ℃ from room temperature at the heating rate of 25 ℃/min in the air atmosphere under normal pressure, carrying out heat preservation and calcination for 3h, and removing carbon powder through oxidation to obtain the porous ceramic.
The embodiment of the application provides a treatment process of overhaul residues of an aluminum electrolytic cell, the process sorts the overhaul residues of the aluminum electrolytic cell to obtain carbon waste and refractory waste, the refractory waste can be used as a raw material to prepare a ceramic material, the carbon waste can be used as a pore-forming agent and a sintering aid for preparing porous ceramic, the carbon waste and the refractory waste are crushed into powder and then mixed to prepare a ceramic blank, the ceramic blank is calcined at high temperature to respectively remove sodium cyanide and sodium fluoride to obtain a ceramic intermediate, and the ceramic intermediate is subjected to carbon removal to obtain the porous ceramic. The treatment process can produce the silicon carbide-silicon nitride porous ceramic, has high porosity, high strength, good toughness and great industrial prospect, removes cyanide and fluoride in the high-temperature calcination process, is beneficial to harmless treatment of overhaul slag, reduces environmental pollution, and solves the problems of environmental pollution caused by solid waste of the overhaul slag and economic value generated by reutilization of the solid waste in the aluminum electrolysis industry.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The treatment process of the overhaul slag of the aluminum electrolytic cell is characterized by comprising the following steps of:
s1, sorting overhaul residues of the aluminum electrolytic cell to respectively obtain carbon waste and refractory waste;
s2, respectively crushing and ball-milling the carbon waste and the refractory waste to obtain carbon powder and ceramic powder;
s3, mixing the carbon powder and the ceramic powder according to a proportion, adding the mixture into a polyvinyl alcohol solution, and carrying out ball milling to obtain slurry; injecting the slurry into a mold, curing and demolding to obtain a ceramic blank;
s4, heating the ceramic blank to 1500-1600 ℃ from room temperature in an inert atmosphere under normal pressure, carrying out heat preservation calcination for 1-2h, gasifying sodium cyanide in the ceramic blank, and allowing the gasified sodium cyanide to enter a purification system to be absorbed by bleaching liquid; heating to 1700 to 2100 ℃, calcining for 1 to 5h under heat preservation, gasifying sodium fluoride in the ceramic blank, allowing the gasified sodium fluoride to enter a purification system to be absorbed by activated alumina to form fluorine-carrying alumina, and then taking the fluorine-carrying alumina as a raw material to enter aluminum electrolysis production again; then cooling to room temperature to obtain a ceramic intermediate;
and S5, heating the ceramic intermediate to 600-800 ℃ from room temperature in an air atmosphere at normal pressure, carrying out heat preservation calcination for 3-5 hours, and removing carbon powder through oxidation to obtain the porous ceramic.
2. The treatment process of the overhaul slag of the aluminum electrolytic cell according to claim 1, wherein in the step S1, the carbonaceous waste is a cathode carbon block or/and a special-shaped carbon block.
3. The treatment process for the overhaul slag of the aluminum electrolytic cell according to claim 1, wherein in the step S1, the refractory waste is one or more of insulating bricks, refractory bricks, impermeable materials and castable materials made of silicon carbide-silicon nitride materials.
4. The treatment process of the overhaul slag of the aluminum electrolytic cell according to claim 1, wherein in the step S2, the particle sizes of the carbon powder and the ceramic powder are 0.5 to 5 μm.
5. The treatment process of the overhaul slag of the aluminum electrolytic cell according to claim 1, wherein in the step S3, the carbon powder and the ceramic powder are mixed in proportion, added into a polyvinyl alcohol solution with the mass fraction of 1~5%, and subjected to ball milling for 3 to 10h to obtain the slurry.
6. The treatment process of the overhaul slag of the aluminum electrolytic cell according to claim 5, wherein the carbon powder and the ceramic powder are mixed according to a mass ratio of 1 to 10.
7. The treatment process of the overhaul slag of the aluminum electrolytic cell according to claim 1, wherein in the step S3, the slurry is injected into a mold, and is cured for 5 to 8h at the temperature of 60 ℃, and the ceramic blank is obtained after demolding.
8. The treatment process for the overhaul slag of the aluminum electrolytic cell according to claim 1, wherein in the step S4, the inert atmosphere is a nitrogen atmosphere or an argon atmosphere.
9. The treatment process of the overhaul slag of the aluminum electrolytic cell according to claim 1, wherein in the step S4, the temperature is increased from the room temperature to 1500 to 1600 ℃, and the temperature increase rate is 20 to 30 ℃/min; and then heating to 1700 to 2100 ℃ at a heating rate of 5 to 10 ℃/min.
10. The treatment process of the overhaul slag of the aluminum electrolytic cell as claimed in claim 1, wherein in the step S5, the temperature is raised from room temperature to 600 to 800 ℃, and the temperature raising rate is 20 to 30 ℃/min.
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| CN102989744A (en) * | 2012-12-04 | 2013-03-27 | 贵州铝城铝业原材料研究发展有限公司 | Method for recycling mixed material dreg of overhauling groove slag of electrolytic cell |
| JP2018062459A (en) * | 2016-10-12 | 2018-04-19 | Ｊｆｅスチール株式会社 | Refractory brick and method for producing the same |
| CN111455407A (en) * | 2020-04-15 | 2020-07-28 | 中南大学 | Method for treating cyanide in overhaul slag of aluminum electrolytic cell |
| CN111499397A (en) * | 2020-04-15 | 2020-08-07 | 中南大学 | Method for preparing reclaimed materials of aluminum oxide and silicon oxide by using electrolytic bath aluminum-silicon overhaul residues |
| CN112939614A (en) * | 2021-03-24 | 2021-06-11 | 湖南国发控股有限公司 | Electrolytic aluminum overhaul slag synergistic ceramic treatment method |
| CN113511881A (en) * | 2021-03-24 | 2021-10-19 | 湖南国发控股有限公司 | Formula and method for preparing foamed ceramic by using overhaul residues |
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102989744A (en) * | 2012-12-04 | 2013-03-27 | 贵州铝城铝业原材料研究发展有限公司 | Method for recycling mixed material dreg of overhauling groove slag of electrolytic cell |
| JP2018062459A (en) * | 2016-10-12 | 2018-04-19 | Ｊｆｅスチール株式会社 | Refractory brick and method for producing the same |
| CN111455407A (en) * | 2020-04-15 | 2020-07-28 | 中南大学 | Method for treating cyanide in overhaul slag of aluminum electrolytic cell |
| CN111499397A (en) * | 2020-04-15 | 2020-08-07 | 中南大学 | Method for preparing reclaimed materials of aluminum oxide and silicon oxide by using electrolytic bath aluminum-silicon overhaul residues |
| CN112939614A (en) * | 2021-03-24 | 2021-06-11 | 湖南国发控股有限公司 | Electrolytic aluminum overhaul slag synergistic ceramic treatment method |
| CN113511881A (en) * | 2021-03-24 | 2021-10-19 | 湖南国发控股有限公司 | Formula and method for preparing foamed ceramic by using overhaul residues |
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