CN115849945B - Treatment process of aluminum electrolysis cell overhaul slag - Google Patents
Treatment process of aluminum electrolysis cell overhaul slag Download PDFInfo
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- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 59
- 239000002893 slag Substances 0.000 title claims abstract description 54
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 46
- 238000005868 electrolysis reaction Methods 0.000 title claims abstract description 43
- 238000000034 method Methods 0.000 title claims abstract description 38
- 239000000919 ceramic Substances 0.000 claims abstract description 101
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 59
- 239000002699 waste material Substances 0.000 claims abstract description 55
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 29
- 238000010438 heat treatment Methods 0.000 claims abstract description 28
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 claims abstract description 28
- 239000000843 powder Substances 0.000 claims abstract description 26
- 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 17
- 238000001354 calcination Methods 0.000 claims abstract description 16
- 239000002002 slurry Substances 0.000 claims abstract description 16
- 235000013024 sodium fluoride Nutrition 0.000 claims abstract description 14
- 239000011775 sodium fluoride Substances 0.000 claims abstract description 14
- 239000012298 atmosphere Substances 0.000 claims abstract description 13
- 238000000498 ball milling Methods 0.000 claims abstract description 10
- 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 7
- 230000001590 oxidative effect Effects 0.000 claims abstract description 6
- 238000001816 cooling Methods 0.000 claims abstract description 5
- 239000000203 mixture Substances 0.000 claims abstract description 5
- 239000000463 material Substances 0.000 claims description 23
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 18
- 229910052710 silicon Inorganic materials 0.000 claims description 18
- 239000010703 silicon Substances 0.000 claims description 18
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 15
- 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
- 238000010521 absorption reaction Methods 0.000 claims description 4
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 4
- 239000012300 argon atmosphere Substances 0.000 claims description 3
- 238000005266 casting Methods 0.000 claims description 3
- 238000004064 recycling Methods 0.000 abstract description 9
- 238000002309 gasification Methods 0.000 abstract description 3
- 238000002360 preparation method Methods 0.000 abstract description 3
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical compound [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 13
- 239000002910 solid waste Substances 0.000 description 9
- 238000003912 environmental pollution Methods 0.000 description 8
- 238000005245 sintering Methods 0.000 description 7
- 101710097688 Probable sphingosine-1-phosphate lyase Proteins 0.000 description 4
- 101710105985 Sphingosine-1-phosphate lyase Proteins 0.000 description 4
- 101710122496 Sphingosine-1-phosphate lyase 1 Proteins 0.000 description 4
- 239000000047 product 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
- 229910010271 silicon carbide Inorganic materials 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 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
- 239000011148 porous material Substances 0.000 description 2
- 239000012752 auxiliary agent Substances 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 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
- 239000003673 groundwater Substances 0.000 description 1
- 238000003837 high-temperature calcination Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000000263 scanning probe lithography Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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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
Abstract
The invention discloses a treatment process of aluminum electrolysis cell overhaul slag, which comprises the following steps: sorting the aluminum electrolysis cell overhaul slag to obtain carbon 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 from room temperature to 1500-1600 ℃ in an inert atmosphere under normal pressure, and removing sodium cyanide in the ceramic blank in a gasification way; heating to 1700-2100 ℃ and removing sodium fluoride in the ceramic blank by gasification; cooling to room temperature to obtain a ceramic intermediate; and (3) heating the ceramic intermediate from room temperature to 600-800 ℃ in an air atmosphere at normal pressure, preserving heat, calcining for 3-5 h, and oxidizing to remove carbon powder to obtain the porous ceramic. The preparation process is simple, waste is changed into valuable, and the economical and pollution-free recycling of the aluminum electrolysis cell overhaul slag is realized.
Description
Technical Field
The invention relates to the technical field of electrolytic aluminum, in particular to a treatment process of aluminum electrolysis cell overhaul slag.
Background
In the electrolytic aluminum production process, the lining structure of the electrolytic tank is deformed and broken due to the permeation and corrosion of molten high-temperature electrolyte, and aluminum liquid and electrolyte in the electrolytic tank leak into the bottom of the electrolytic tank from cracks, so that the electrolytic tank cannot be used normally. Therefore, on average, every 2 to 5 years, the aluminum electrolysis cell needs to be overhauled, and the cathode lining material removed in the process is called overhauling Slag (SPL).
The amount of fluoride in the SPL leaching solution is about 3500mg/L, the amount of cyanide is about 1mg/L, and the amount exceeds the limit value regulated in the standard, and is defined as dangerous waste by the national dangerous waste directory. SPLs, whether stored or buried, require significant investment and operational management costs, and present long-term potential pollution hazards. The SPL mainly comprises components such as cathode carbon blocks, refractory bricks, cathode paste, seepage-proofing materials, casting materials and the like, and the components are treated as dangerous wastes, so that resource waste is caused.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a treatment process of aluminum electrolysis cell overhaul slag, which recycles carbon waste and refractory waste, is used for preparing silicon carbide-silicon nitride porous ceramic, and in the process of sintering the ceramic, sodium cyanide and sodium fluoride are gasified and absorbed, so that the aluminum electrolysis cell overhaul slag is subjected to harmless treatment, the environmental pollution is reduced, and the problems of environmental pollution caused by overhaul slag solid waste and economic value generated by solid waste recycling in the aluminum electrolysis industry are solved.
The technical scheme adopted by the invention is as follows:
a treatment process of aluminum electrolysis cell overhaul slag comprises the following steps:
step S1, sorting aluminum electrolysis cell overhaul slag to obtain carbon waste and refractory waste respectively;
step S2, respectively crushing and ball-milling the carbonaceous waste and the refractory waste to obtain carbon powder and ceramic powder;
step S3, 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;
step S4, heating the ceramic blank to 1500-1600 ℃ from room temperature in an inert atmosphere under normal pressure, preserving heat and calcining for 1-2 hours, gasifying sodium cyanide in the ceramic blank, and allowing the gasified sodium cyanide to enter a purification system for absorption by bleaching liquid; heating to 1700-2100 ℃, preserving heat, calcining for 1-5 h, gasifying sodium fluoride in the ceramic blank, entering a purification system, absorbing by activated alumina, and cooling to room temperature to obtain a ceramic intermediate;
and S5, heating the ceramic intermediate from room temperature to 600-800 ℃ in an air atmosphere at normal pressure, preserving heat, calcining for 3-5 h, and oxidizing to remove carbon powder to obtain the porous ceramic.
In the treatment process of aluminum electrolysis cell overhaul slag disclosed by the application, in the step S1, the carbon waste is cathode carbon blocks or/and special-shaped carbon blocks.
In the treatment process of aluminum electrolysis cell overhaul slag disclosed by the application, in the step S1, the refractory waste is one or more of insulating bricks, refractory bricks, seepage-proofing materials and castable materials made of silicon carbide-silicon nitride materials.
In the treatment process of aluminum electrolysis cell overhaul slag 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 aluminum electrolysis cell overhaul slag disclosed by the application, in the step S3, carbon powder and ceramic powder are mixed in proportion, added into a polyvinyl alcohol solution with the mass fraction of 1-5%, and ball-milled for 3-10 hours to obtain slurry.
In the aluminum electrolysis cell overhaul slag treatment process disclosed by the application, the carbon powder and the ceramic powder are mixed according to the mass ratio of 1-10:100.
In the treatment process of aluminum electrolysis cell overhaul slag disclosed by the application, in the step S3, slurry is injected into a die, cured for 5-8 hours at the temperature of 60 ℃, and demoulded to obtain a ceramic blank.
In the treatment process of aluminum electrolysis cell overhaul slag disclosed in the application, in the step S4, the inert atmosphere is a nitrogen atmosphere or an argon atmosphere.
In the treatment process of aluminum electrolysis cell overhaul slag disclosed by the application, in the step S4, the temperature is raised from room temperature to 1500-1600 ℃, and the temperature raising rate is 20-30 ℃/min; and then heating to 1700-2100 ℃ at a heating rate of 5-10 ℃/min.
In the treatment process of aluminum electrolysis cell overhaul slag disclosed by the application, in the step S5, the temperature is raised to 600-800 ℃ from room temperature, and the temperature raising rate is 20-30 ℃/min.
Compared with the prior art, the invention has the beneficial effects that:
the process recycles carbon waste and refractory waste of aluminum cell overhaul slag, is used for preparing silicon carbide-silicon nitride porous ceramic, and is used for gasifying and absorbing sodium cyanide and sodium fluoride in the process of sintering the ceramic, so that the aluminum cell overhaul slag is subjected to harmless treatment, environmental pollution is reduced, and the problems of environmental pollution caused by overhaul slag solid waste and economic value generated by solid waste recycling in the aluminum electrolysis industry are solved. The porous ceramic is prepared by the aluminum cell overhaul slag, the preparation process is simple, the high-value silicon carbide-silicon nitride porous ceramic can be obtained, the recycling value of the aluminum cell overhaul slag is improved, waste is changed into valuable, and the economical and pollution-free recycling of the aluminum cell overhaul slag is realized.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of a treatment process of aluminum electrolysis cell overhaul slag.
Detailed Description
In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures are described in detail below. It is to be understood that the specific embodiments described herein are for purposes of illustration only and are not limiting. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present application are shown in the drawings. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
The terms "comprising" and "having" and any variations thereof herein are intended to cover a non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed steps or elements but may 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. The term "and/or" as used herein 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 may be included in at least one embodiment of the application. The appearances of such phrases 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. Those of skill in the art will explicitly and implicitly appreciate 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 electrolysis cell overhaul slag, which mainly aims to solve the problems of resource waste and the like caused by treating all aluminum electrolysis cell overhaul slag as dangerous waste in the prior art.
The treatment process of the aluminum electrolysis cell overhaul slag disclosed by the application comprises the following steps of:
step S1, sorting aluminum electrolysis cell overhaul slag to obtain carbon waste and refractory waste respectively;
step S2, respectively crushing and ball-milling the carbonaceous waste and the refractory waste to obtain carbon powder and ceramic powder;
step S3, 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;
step S4, heating the ceramic blank to 1500-1600 ℃ from room temperature in an inert atmosphere under normal pressure, preserving heat and calcining for 1-2 hours, gasifying sodium cyanide in the ceramic blank, and allowing the gasified sodium cyanide to enter a purification system for absorption by bleaching liquid; heating to 1700-2100 ℃, preserving heat, calcining for 1-5 h, gasifying sodium fluoride in the ceramic blank, entering a purification system, absorbing by activated alumina to form fluorine-carrying alumina, and then taking the fluorine-carrying alumina as a raw material to enter aluminum electrolysis production; cooling to room temperature to obtain a ceramic intermediate;
and S5, heating the ceramic intermediate from room temperature to 600-800 ℃ in an air atmosphere at normal pressure, preserving heat, calcining for 3-5 h, and oxidizing to remove carbon powder to obtain the porous ceramic.
The aluminum electrolysis cell overhaul slag is separated, and carbon waste and refractory waste are selected. The refractory waste is mainly silicon nitride-silicon carbide material, and can be used as ceramic raw material to prepare ceramic products. The carbon waste is mainly carbon material, and can be mixed with ceramic raw material to prepare ceramic product, and can be used as pore-forming agent and sintering auxiliary agent. The silicon carbide-silicon nitride material has high 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, thereby improving the economic value.
Since the aluminum cell overhaul slag contains a certain amount of sodium fluoride and sodium cyanide, the aluminum cell overhaul slag is made into ceramic products, and after water immersion, the fluoride and the cyanide are dissolved out, and if the aluminum cell overhaul slag permeates into the ground, the ground and the ground 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 heat preservation and calcination are carried out for 1-2 hours, and the sodium cyanide in the ceramic blank is gasified and enters a purification system to be absorbed by bleaching liquid; and heating to 1700-2100 ℃, preserving heat, calcining for 1-5 h, gasifying sodium fluoride in the ceramic blank, entering a purification system, absorbing by activated alumina to form fluorine-carrying alumina, and then taking the fluorine-carrying alumina as a raw material to enter aluminum electrolysis production. 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.
And (3) 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 under normal pressure, preserving heat, calcining for 3-5 hours, oxidizing and removing carbon powder to obtain porous ceramic, and improving the ceramic porosity to a design level.
The method recycles the carbon waste and the refractory waste of the aluminum cell overhaul slag, is used for preparing the silicon carbide-silicon nitride porous ceramic, gasifies and absorbs sodium cyanide and sodium fluoride in the process of sintering the ceramic, realizes the harmless treatment of the aluminum cell overhaul slag, reduces environmental pollution, and solves the problems of environmental pollution caused by the overhaul slag solid waste and economic value generation caused by the solid waste reuse in the aluminum electrolysis industry. The porous ceramic is prepared by the aluminum cell overhaul slag, the preparation process is simple, the high-value silicon carbide-silicon nitride porous ceramic can be obtained, the recycling value of the aluminum cell overhaul slag is improved, waste is changed into valuable, and the economical and pollution-free recycling of the aluminum cell overhaul slag is realized.
In one embodiment, in step S1, the carbonaceous waste material is a cathode carbon block or/and a shaped carbon block. The cathode carbon block and the special-shaped carbon block are the main components of the overhaul slag of the aluminum electrolysis cell, and are recycled to be used as pore formers and sintering aids for preparing porous ceramics, so that the problem of economic value generated by reutilization of the overhaul slag solid waste in the aluminum electrolysis industry is solved.
In one embodiment, in 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. The main materials of the insulating brick, the refractory brick, the anti-seepage material and the castable are silicon nitride-silicon carbide, the silicon carbide-silicon nitride material has high price, and if the materials are simply separated and recycled, the recycling value is low, and the materials are used for preparing the silicon carbide-silicon nitride porous ceramic, are applied to the sewage treatment industry, and improve the economic value.
In one embodiment, in step S2, the particle size of the carbon powder and the ceramic powder is 0.5 to 5 μm. Specifically, the particle diameters of the carbon powder and the ceramic powder may be 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, etc. The carbon waste and the refractory waste are respectively crushed and ball-milled to obtain carbon powder and ceramic powder with small particle size, so that the ceramic blank is convenient to prepare.
In one embodiment, in step S3, the carbon powder and the ceramic powder are mixed according to a proportion, added into a polyvinyl alcohol solution with the mass fraction of 1-5%, and ball-milled for 3-10 hours to obtain slurry. The method sorts the carbonaceous waste and the refractory waste, respectively crushes and ball mills the carbonaceous waste and the refractory waste, obtains carbon powder and ceramic powder, and is convenient for mixing the carbon powder and the ceramic powder in different proportions to prepare porous ceramic products with different porosities.
Specifically, the mass fraction of the polyvinyl alcohol solution may be 1%, 2%, 3%, 4%, 5%, etc., preferably 3%. Specifically, the ball milling time may be 3 hours, 5 hours, 8 hours, 10 hours, etc., preferably 8 hours.
In one embodiment, the carbon powder and the ceramic powder are mixed according to a mass ratio of 1-10:100. Specifically, the mass ratio of the carbon powder to the ceramic powder may be 1:100, 3:100, 5:100, 8:100, 10:100, etc., and an appropriate mass ratio may be selected according to the porosity required for the porous ceramic.
In one embodiment, in step S3, the slurry is injected into a mold, cured at 60 ℃ for 5-8 hours, 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 room temperature to 1500-1600 ℃ at a speed of 20-30 ℃/min; and then heating to 1700-2100 ℃ at a heating rate of 5-10 ℃/min.
In one embodiment, in step S5, the temperature is raised from room temperature to 600-800 ℃ at a rate of 20-30 ℃/min.
In a specific implementation scene, the aluminum electrolysis cell overhaul slag is separated, cathode carbon blocks and special-shaped carbon blocks are selected as carbon waste materials, insulating bricks, refractory bricks, seepage-proofing materials and casting materials which are composed of silicon nitride-silicon carbide are selected as refractory waste materials, and the carbon waste materials and the refractory waste materials are respectively crushed and ball-milled to obtain carbon powder and ceramic powder with the particle size of 0.5-5 mu m. Mixing the carbon powder and the ceramic powder according to the mass ratio of 5:100, adding the mixture into a 3% polyvinyl alcohol solution, ball milling for 8 hours to obtain slurry, injecting the slurry into a mold, solidifying and demolding to obtain a ceramic blank. Heating the ceramic blank from room temperature to 1500-1600 ℃ at a heating rate of 25 ℃/min in nitrogen atmosphere at normal pressure, preserving heat and calcining for 2h, gasifying sodium cyanide in the ceramic blank, and allowing the ceramic blank to enter a purification system for absorption by bleaching liquid; heating to 1700-2100 ℃ at a heating rate of 10 ℃/min, preserving heat and calcining for 3 hours, gasifying sodium fluoride in the ceramic blank, entering a purification system, absorbing by activated alumina to form fluorine-carrying alumina, and then re-entering the alumina as a raw material for electrolytic production; and cooling to room temperature to obtain the ceramic intermediate. And heating the ceramic intermediate from room temperature to 600-800 ℃ at a heating rate of 25 ℃/min in an air atmosphere at normal pressure, preserving heat, calcining for 3 hours, and oxidizing to remove carbon powder to obtain the porous ceramic.
The embodiment of the application provides a treatment process of aluminum electrolysis cell overhaul slag, which is used for separating the aluminum electrolysis cell overhaul slag to obtain carbon waste and refractory waste, wherein the refractory waste can be used as a raw material for preparing ceramic materials, the carbon waste can be used as a pore-forming agent and a sintering aid for preparing porous ceramics, the carbon waste and the refractory waste are crushed into powder, the powder is mixed to prepare ceramic blanks, the ceramic blanks are calcined at high temperature, sodium cyanide and sodium fluoride are removed respectively, a ceramic intermediate is obtained, and carbon is removed from the ceramic intermediate, so that porous ceramics are obtained. The treatment process can be used for producing the silicon carbide-silicon nitride porous ceramic, has high porosity, high strength, good toughness and great industrial prospect, is beneficial to harmless treatment of the overhaul slag by removing cyanide and fluoride in the high-temperature calcination process, reduces environmental pollution, and solves the problems of environmental pollution caused by the overhaul slag solid waste 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, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. The treatment process of the aluminum electrolysis cell overhaul slag is characterized by comprising the following steps of:
step S1, sorting aluminum electrolysis cell overhaul slag to obtain carbon waste and refractory waste respectively;
step S2, respectively crushing and ball-milling the carbonaceous waste and the refractory waste to obtain carbon powder and ceramic powder;
step S3, 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; wherein, the carbon powder and the ceramic powder are mixed according to the mass ratio of 1-10:100;
step S4, heating the ceramic blank to 1500-1600 ℃ from room temperature in an inert atmosphere under normal pressure, preserving heat and calcining for 1-2 hours, gasifying sodium cyanide in the ceramic blank, and allowing the gasified sodium cyanide to enter a purification system for absorption by bleaching liquid; heating to 1700-2100 ℃, preserving heat, calcining for 1-5 h, gasifying sodium fluoride in the ceramic blank, entering a purification system, absorbing by activated alumina to form fluorine-carrying alumina, and then taking the fluorine-carrying alumina as a raw material to enter aluminum electrolysis production; cooling to room temperature to obtain a ceramic intermediate;
step 5, heating the ceramic intermediate from room temperature to 600-800 ℃ in an air atmosphere at normal pressure, preserving heat, calcining for 3-5 h, and oxidizing to remove carbon powder to obtain porous ceramic;
in the step S1, the carbon waste is a cathode carbon block or/and a special-shaped carbon block; the refractory waste is one or more of insulating bricks, refractory bricks, seepage-proofing materials and casting materials made of silicon carbide-silicon nitride materials;
in the step S4, the temperature is raised from room temperature to 1500-1600 ℃ at a heating rate of 20-30 ℃/min; heating to 1700-2100 ℃ at a heating rate of 5-10 ℃/min;
in the step S5, the temperature is raised from room temperature to 600-800 ℃ at a heating rate of 20-30 ℃/min.
2. The aluminum electrolysis cell overhaul slag treatment process according to claim 1, wherein in the step S2, the particle sizes of the carbon powder and the ceramic powder are 0.5-5 μm.
3. The aluminum electrolysis cell overhaul slag treatment process according to claim 1, wherein in the step S3, carbon powder and ceramic powder are mixed according to a proportion, added into a polyvinyl alcohol solution with the mass fraction of 1-5%, and ball-milled for 3-10 hours to obtain slurry.
4. The aluminum electrolysis cell overhaul slag treatment process according to claim 1, wherein in the step S3, the slurry is injected into a mold, cured for 5-8 hours at 60 ℃, and demolded to obtain a ceramic blank.
5. The process of claim 1, wherein in the step S4, the inert atmosphere is a nitrogen atmosphere or an argon atmosphere.
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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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| 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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