CN111170299A - Method for recovering waste cathode carbon blocks from aluminum electrolysis - Google Patents
Method for recovering waste cathode carbon blocks from aluminum electrolysis Download PDFInfo
- Publication number
- CN111170299A CN111170299A CN202010062001.4A CN202010062001A CN111170299A CN 111170299 A CN111170299 A CN 111170299A CN 202010062001 A CN202010062001 A CN 202010062001A CN 111170299 A CN111170299 A CN 111170299A
- Authority
- CN
- China
- Prior art keywords
- slurry
- carbon
- waste cathode
- recovering
- roasting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/20—Graphite
- C01B32/205—Preparation
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/20—Graphite
- C01B32/21—After-treatment
- C01B32/215—Purification; Recovery or purification of graphite formed in iron making, e.g. kish graphite
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/48—Halides, with or without other cations besides aluminium
- C01F7/50—Fluorides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Silicon Compounds (AREA)
Abstract
The invention discloses a method for recovering waste cathode carbon blocks in aluminum electrolysis, which comprises the following steps: (1) crushing and screening the waste cathode carbon blocks to obtain carbon particles; (2) mixing the carbon particles with a sulfuric acid solution to obtain slurry A, and then carrying out pressure leaching to obtain slurry B; (3) evaporating and concentrating the slurry B until the mass percent of water is lower than 8% to obtain slurry C; (4) adding concentrated sulfuric acid into the slurry C to obtain slurry D, roasting at the temperature of 150-300 ℃ for 0.5-10 hours, and roasting at the temperature of 300-600 ℃ for 0.5-8 hours to obtain roasted carbon; (5) and heating the roasted carbon to 1200-3000 ℃, and preserving the heat for 0.5-20 hours to obtain the purified carbon. The method does not generate high-temperature fluorine-containing flue gas and fluorine-containing wastewater in the treatment process, and can recover fluorine, aluminum and carbon materials, thereby realizing comprehensive recovery and cleaning treatment of the aluminum electrolysis waste cathode carbon block.
Description
Technical Field
The invention belongs to the technical field of comprehensive utilization of electrolytic aluminum industrial solid wastes, and particularly relates to recovery of aluminum electrolysis waste cathode carbon block resources.
Background
The aluminum electrolysis cathode is deformed, raised and broken under the actions of molten salt and aluminum liquid, such as erosion, scouring and thermal stress, so as to generate a waste cathode carbon block. In general, about 10kg of waste cathode carbon blocks are produced per 1 ton of electrolytic aluminum, the global electrolytic aluminum yield in 2018 is 6434 ten thousand tons, and the quantity of the produced waste cathode carbon blocks is over 60 ten thousand tons, so that the quantity is huge. The aluminum electrolysis waste cathode carbon block contains carbon, aluminum fluoride, sodium fluoride, calcium fluoride, cryolite, alumina, nepheline, cyanide and other substances. Wherein the carbon content accounts for 50-70%, and the carbon is highly graphitized, and the rest of fluoride is an important component of the electrolyte and is a renewable resource. The separation and recovery of the waste cathode carbon blocks are beneficial to the sustainable development of the electrolytic aluminum industry and can realize good economic benefit.
At present, the recovery method aiming at the waste cathode carbon block of the aluminum electrolytic cell can be summarized into two recovery processes, namely a pyrogenic process taking a high-temperature roasting method as a core and a wet process mainly taking a flotation and leaching mode as a main process. Wherein, the pyrogenic process utilizes high-calorific value graphite carbon material in the waste cathode carbon block as fuel for combustion, recovers electrolyte and eliminates the harm brought by fluoride and cyanide. However, a large amount of fluoride in the waste cathode carbon block can volatilize under the condition of high temperature (1000 ℃), and serious corrosion is caused to subsequent flue gas treatment equipment. Moreover, the direct combustion of carbon materials with highly graphitized characteristics also causes resource waste. The wet method can realize the joint recovery of the graphite carbon material and the fluorine-containing compound, and realize the comprehensive utilization of the waste cathode carbon block. However, a large amount of fluorine-containing wastewater is generated in the wet process and is difficult to treat.
In order to solve the problems of high-temperature fluorine-containing flue gas and fluorine-containing wastewater, a series of waste cathode carbon block treatment processes mainly based on sulfating roasting are provided. In the patent CN 110127649A, waste cathode carbon blocks are treated in a mirabilite mode through oxidation decyanation, sulfating roasting defluorination and concentration crystallization, but concentrated sulfuric acid which is 5-7 times of the mass of the waste cathode carbon blocks and sodium hydroxide which is 2-3 times of the mass of the waste cathode carbon blocks are consumed in the treatment process, and waste water with the mass of more than 15 times of the mass of the waste cathode carbon blocks is generated; the patent CN1320491A adopts a combined acid-base roasting mode to treat the waste cathode carbon block, but the obtained product sodium sulfate contains fluorine, alumina contains silicon, fluoride contains iron, and the quality is difficult to ensure; after the waste cathode carbon blocks are treated by sulfating roasting in the patents GB2056422A and US005955042A, high-temperature treatment is carried out, and in the process, the graphite carbon material is used as fuel to be burnt at a low value, so that resources are wasted. It can be seen that the existing sulfating roasting process also has the problems of large waste water amount and difficult recovery of carbonaceous materials.
Disclosure of Invention
Aiming at the defects of the method, the invention aims to provide the method for recovering the waste cathode carbon blocks in the aluminum electrolysis, which does not generate high-temperature fluorine-containing flue gas and waste water in the treatment process and can recover fluorine to return to an aluminum electrolysis system to obtain a high-purity carbon material, thereby realizing the comprehensive recovery of the waste cathode carbon blocks in the aluminum electrolysis and the cleaning treatment of the waste cathode carbon blocks.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
a method for recovering waste cathode carbon blocks in aluminum electrolysis comprises the following steps:
mixing the waste cathode carbon particles with a sulfuric acid solution to obtain a slurry A, and leaching to obtain a slurry B, wherein the concentration of the sulfuric acid solution is 0.5-8 mol/L; and (3) evaporating and concentrating the slurry B to obtain slurry C, adding concentrated sulfuric acid into the slurry C to obtain slurry D, roasting the slurry D at 150-300 ℃ for the first time, roasting at 300-600 ℃ for the second time to obtain roasted carbon, and roasting the roasted carbon to obtain the carbon-based catalyst.
In the present invention, concentrated sulfuric acid is H defined in the prior art2SO4H of 70% or more by mass2SO4An aqueous solution of (a).
In a preferred scheme, the waste cathode carbon particles are obtained by crushing and screening waste cathode carbon blocks.
In a preferable scheme, the concentration of the sulfuric acid solution is 1-3 mol/L.
In a preferred embodiment, in the slurry a, in terms of mole ratio, Si: 1, S: 2.05 to 3.0.
Further preferably, in the slurry a, in terms of mole ratio, Si: 1, S: 2.1 to 3.0.
Still more preferably, in the slurry a, in terms of mole ratio, Si: 1, S: 2.10 to 2.25.
Preferably, the leaching is pressure leaching.
In the preferable scheme, the leaching temperature is 100-300 ℃, the leaching time is 1-10 h, and the pressure is 0.1-9 MPa.
Further preferably, the leaching temperature is 150-250 ℃, the leaching time is 2-5 h, and the pressure is 0.4-4 MPa. And absorbing gas by using alkali liquor in the leaching process.
In the invention, Si element in carbon particles is taken as a target in leaching, a sulfuric acid solution is correspondingly added, and soluble sodium fluoride and silicon dioxide or silicate react under acidic conditions in the process as follows: nMoO SiO2+H2SO4+[NaF+CaF2+AlF3+Na3AlF6]→H2SiF6(l)+H4SiO4(l)+Mem·(SO4)+[Na2SO4+CaSO4+Al2(SO4)3](1)
This reaction converts the intractable solid aluminosilicate and silica into liquid silicofluoric acid and colloidal orthosilicic acid, which is more easily removed in the next two-stage calcination because of its high specific surface area and high chemical activity due to its volatility. But because the high concentration sulfuric acid mixes with the cathode carbon block, the following reactions occur rapidly:
[NaF+CaF2+AlF3+Na3AlF6]+H2SO4+H2O→HF(l)+CaSO4+nNa2SO4·Al2(SO4)3·mH2O (2)
the waste cathode is seriously agglomerated, the leaching effect is influenced, and the carbon purity is influenced, so that the concentration of the leaching acid is not high.
Preferably, the slurry B is evaporated and concentrated at 100-200 ℃, preferably 120-180 ℃, to obtain slurry C. Recovering the steam generated in the evaporation concentration process of the slurry B,
the slurry B is evaporated and concentrated because concentrated sulfuric acid is directly added into the slurry B without concentration, the slurry can be violently volatilized due to excessive moisture at a section of roasting temperature, volatilized water vapor not only can take away sulfuric acid to cause acid loss to influence the removal of fluorine, but also can aggravate the corrosion performance of flue gas to corrode equipment.
Preferably, in the slurry C, the mass fraction of water is less than 8%.
In a preferable scheme, the concentration of the concentrated sulfuric acid is 17-18.4 mol/L.
Preferably, in the slurry D, the molar ratio of F: 1, S: 0.5 to 5.
More preferably, in the slurry D, in terms of molar ratio, F: 1, S: 1 to 4.5.
In the preferable scheme, the temperature of the first-stage roasting is 150-250 ℃, and the time of the first-stage roasting is 0.5-10 h; preferably 1-5 h.
In the actual operation process, the flue gas generated by the first-stage roasting is absorbed and recovered with an alumina dry method.
In the invention, the first-stage roasting aims at removing fluorine and silicon in the carbon block, so that a large amount of fluoride is prevented from volatilizing to corrode equipment in a high-temperature roasting stage, and the carbon purity is improved, wherein the reaction generated in the first-stage roasting process is as follows: [ NaF + AlF ]3+CaF2+Na3AlF6]+H2SO4→HF(g)+CaSO4+nNa2SO4·Al2(SO4)3(3)
[nMeO·SiO2+H4SiO4]+H2SO4+NaF→Mem·(SO4)+SiF4(g)(4)
H2SiF6(l)→H2SiF6(g)(5)
In the preferable scheme, the temperature of the second-stage roasting is 350-500 ℃, and the time of the second-stage roasting is 0.5-8 h; preferably 1 to 3 hours.
The purpose of the second-stage roasting in the invention is to remove redundant sulfuric acid in the carbon block and avoid the sulfuric acid from decomposing and volatilizing in the high-temperature roasting stage to generate high-temperature sulfur-containing flue gas to corrode equipment, and the reaction generated in the second-stage roasting process is as follows:
H2SO4(l)→H2O(g)+SO3(g)(6)
H2SO4(l)→H2SO4(g)(7)
in the preferable scheme, the flue gas generated by the second-stage roasting is absorbed by the steam recovered in the evaporation and concentration process of the slurry B, and the acid liquor formed after absorption is prepared into sulfuric acid solution to be returned for leaching the waste cathode carbon particles. Through the operation, the recycling of the sulfuric acid solution is realized, and the discharge of waste water is avoided.
In the preferable scheme, the calcining temperature is 1200-3000 ℃, and the calcining time is 0.5-20 h.
Further preferably, the roasted carbon is calcined at 1200-2200 ℃, preferably 1400-2200 ℃ for 4-10 h to obtain the carbon material. The purity of the obtained carbon material is more than 97.5 percent.
Further preferably, the roasted carbon is calcined at 2200-3000 ℃, preferably 2200-2600 ℃ for 4-7 h to obtain graphite powder. The purity of the obtained graphite powder is more than 99%.
And absorbing the flue gas generated in the calcining process by using alkaline liquor.
The high-temperature calcination aims at volatilizing and removing sulfate generated in the two-stage calcination process and recovering the sulfate, wherein the reaction generated in the process is as follows:
Mem·(SO4)+C→MenS(g)+CO(g)(8)
Na2(SO4)(s)→Na2(SO4)(g)(9)
preferably, the calcination is carried out in an inert atmosphere, a reducing atmosphere or an atmosphere having an oxygen partial pressure of less than 1000 Pa.
Wherein the inert atmosphere is provided by at least one of helium, nitrogen and argon, and the reducing atmosphere is provided by any one of hydrogen, carbon monoxide, methane, ethane and propane.
The invention adopts an acidification leaching mode to convert the solid silicon dioxide and silicate which are difficult to react into liquid silicofluoric acid and colloidal orthosilicic acid which are easy to react, low-temperature roasting is carried out to recover fluorine in a gaseous state, and high-temperature roasting is carried out to obtain the purified carbon. In the process, steam generated by concentration is used for absorbing sulfur dioxide to prepare acid and returns to acid leaching, so that circulation of water and sulfur elements is realized. The whole process does not produce high-temperature fluorine-containing flue gas and waste water, and realizes the comprehensive recovery of fluorine and carbon materials and the cleaning treatment of waste cathode carbon blocks.
The invention has the advantages that:
1. the invention utilizes the interaction of sulfuric acid and non-carbon components in the waste cathode carbon block to generate low-temperature fluorine-containing flue gas, and can solve the problem of equipment corrosion caused by high-temperature fluoride in the existing pyrogenic process; waste water and waste residue are not generated in the process, and the problems of waste water and secondary pollution in wet treatment and the like can be solved.
2. The invention uses the steam generated by concentration to absorb sulfur dioxide gas to prepare acid and return to leaching, thereby realizing the recycling of water and sulfur elements and realizing the cleaning treatment of the waste cathode carbon block.
3. The method converts silicon dioxide and silicate which are difficult to remove in the waste cathode carbon block into silicon fluoric acid and orthosilicic acid which are easy to remove, and is beneficial to the removal of silicon and the deep purification of carbon materials.
4. The method can recover fluorine in the waste cathode carbon block, obtain high-purity carbon materials and realize efficient utilization of the waste cathode carbon block.
Drawings
FIG. 1 is a process flow diagram of a method for recovering waste cathode carbon blocks from aluminum electrolysis according to the present invention. The raw material is the waste cathode carbon block after overhaul in a certain electrolytic aluminum plant, and after treatment, the comprehensive recovery and cleaning treatment of the waste cathode carbon block can be realized.
Detailed Description
The following examples are carried out according to the above operation method, wherein the aluminum electrolysis waste cathode carbon blocks used in the examples and the comparative examples have the same components, and C: 70.91%, O: 3.81%, F: 10.1%, Na: 5.19%, Al: 3.49%, Si: 3.21%, S: 0.52%, Ca: 1.06%, Fe: 1.71, others: 0.78 percent.
Example 1
(1) Crushing and screening the cathode carbon block to obtain carbon particles;
(2) aiming at Si element in the carbon particles and S element in the sulfuric acid solution, adding the sulfuric acid solution to ensure that the molar ratio of Si and S in the slurry A is 1: 2.10, the concentration of the sulfuric acid solution is 3mol/L, the soaking time is 5 hours, the temperature is 150 ℃, the pressure is 0.4MPa, and gas generated in the process is absorbed by alkali liquor.
(3) And (3) evaporating and concentrating the slurry B at the temperature of 120 ℃, collecting generated steam to obtain the slurry C, wherein the mass percent of the water in the slurry C is 8%.
(4) Adding concentrated sulfuric acid to the slurry D to make the F, S molar ratio in the slurry D be 1: 1.0, the concentration of the concentrated sulfuric acid is 18.4mol/L, then roasting is carried out for 5 hours at the temperature of 150 ℃, the roasting is a first-stage roasting, and the flue gas generated in the process is absorbed by an alumina dry method to recover fluorine; then roasting for 3 hours at 350 ℃, namely, two-stage roasting to obtain roasted carbon, and recovering the generated flue gas; in the process, the silicon removal rate is 98.84 percent, and the fluorine removal rate is 99.52 percent.
(5) The roasted carbon is insulated for 10 hours at 1400 ℃ in the atmosphere of carbon monoxide, and a carbon material with the purity of 97.65 percent is obtained; the flue gas generated in the process is absorbed by sodium hydroxide solution; and (3) absorbing the flue gas subjected to dust collection treatment in the step (4) and the flue gas generated by secondary roasting in the step (3) by using the steam collected in the step (2) to prepare acid, and returning the obtained acid to the step (1) for leaching.
Example 2
(1) Crushing and screening the waste cathode carbon blocks to obtain carbon particles;
(2) aiming at Si element in the carbon particles and S element in the sulfuric acid solution, adding the sulfuric acid solution to ensure that the molar ratio of Si and S in the slurry A is 1: 2.15, the concentration of the sulfuric acid solution is 2mol/L, the soaking time is 3 hours, the temperature is 200 ℃, the pressure is 1.6MPa, and gas generated in the process is absorbed by alkali liquor.
(3) And (3) evaporating and concentrating the slurry B at the temperature of 160 ℃, collecting generated steam to obtain the slurry C, wherein the mass percent of the water in the slurry C is 7%.
(4) Adding concentrated sulfuric acid to the target F element and concentrated sulfuric acid in the slurry C and the target sulfur element in the slurry C so that the molar ratio of F, S in the slurry D is 1: 2.0, the concentrated sulfuric acid concentration is 18mol/L, then roasting is carried out for 3 hours at the temperature of 200 ℃, the roasting is a first-stage roasting, and the flue gas generated in the process is absorbed by an alumina dry method to recover fluorine; then roasting for 2 hours at 450 ℃, namely, two-stage roasting to obtain roasted carbon, and recovering the generated flue gas; in the process, the silicon removal rate is 98.75 percent, and the fluorine removal rate is 99.50 percent.
(5) Keeping the temperature of the baked carbon at 2000 ℃ for 7 hours in a hydrogen atmosphere to obtain a carbon material with the purity of 98.74 percent; the flue gas generated in the process is absorbed by potassium hydroxide solution; and (3) absorbing the flue gas subjected to dust collection treatment in the step (4) and the flue gas generated by secondary roasting in the step (3) by using the steam collected in the step (2) to prepare acid, and returning the obtained acid to the step (1) for leaching.
Example 3
(1) Crushing and screening the waste cathode carbon blocks to obtain carbon particles;
(2) aiming at Si element in the carbon particles and S element in the sulfuric acid solution, adding the sulfuric acid solution to ensure that the molar ratio of Si and S in the slurry A is 1: 2.20, the concentration of the sulfuric acid solution is 1mol/L, the soaking time is 1 hour, the temperature is 250 ℃, the pressure is 4MPa, and gas generated in the process is absorbed by alkali liquor.
(3) And (3) evaporating and concentrating the slurry B at the temperature of 180 ℃, collecting generated steam to obtain the slurry C, wherein the mass percent of the water in the slurry C is 6%.
(4) Adding concentrated sulfuric acid to the target F element and concentrated sulfuric acid in the slurry C and the target sulfur element in the slurry C so that the molar ratio of F, S in the slurry D is 1: 3.0, roasting the concentrated sulfuric acid with the concentration of 17mol/L at 250 ℃ for 1 hour, wherein the roasting is a first-stage roasting, and the flue gas generated in the process is absorbed by an alumina dry method to recover fluorine; then roasting for 1 hour at 500 ℃, namely, two-stage roasting to obtain roasted carbon, and recovering the generated flue gas; in the process, the silicon removal rate is 98.89%, and the fluorine removal rate is 99.54%.
(5) The roasted carbon is insulated for 4 hours at 2600 ℃ under the atmosphere of argon gas, and graphite powder with the purity of 99.95 percent is obtained; the flue gas generated in the process is absorbed by potassium hydroxide solution; and (3) absorbing the flue gas subjected to dust collection treatment in the step (4) and the flue gas generated by secondary roasting in the step (3) by using the steam collected in the step (2) to prepare acid, and returning the obtained acid to the step (1) for leaching.
Example 4
(1) Crushing and screening the waste cathode carbon blocks to obtain carbon particles;
(2) aiming at Si element in the carbon particles and S element in the sulfuric acid solution, adding the sulfuric acid solution to ensure that the molar ratio of Si and S in the slurry A is 1: 2.25, the concentration of the sulfuric acid solution is 1mol/L, the soaking time is 1.5 hours, the temperature is 250 ℃, the pressure is 4MPa, and gas generated in the process is absorbed by alkali liquor.
(3) And (3) evaporating and concentrating the slurry B at the temperature of 180 ℃, collecting generated steam to obtain the slurry C, wherein the mass percent of water in the slurry C is 5%.
(4) Adding concentrated sulfuric acid to the target F element and concentrated sulfuric acid in the slurry C and the target sulfur element in the slurry C so that the molar ratio of F, S in the slurry D is 1: 4.5, the concentrated sulfuric acid concentration is 17mol/L, then roasting is carried out for 1 hour at the temperature of 250 ℃, the roasting is a first-stage roasting, and the flue gas generated in the process is absorbed by an alumina dry method to recover fluorine; then roasting for 1 hour at 500 ℃, namely, two-stage roasting to obtain roasted carbon, and recovering the generated flue gas; in the process, the silicon removal rate is 99.01 percent, and the fluorine removal rate is 99.60 percent.
(5) The roasted carbon is kept warm for 6 hours at 2300 ℃ under the argon atmosphere to obtain graphite powder with the purity of 99.18 percent; the flue gas generated in the process is absorbed by sodium hydroxide solution; and (3) absorbing the flue gas subjected to dust collection treatment in the step (4) and the flue gas generated by secondary roasting in the step (3) by using the steam collected in the step (2) to prepare acid, and returning the obtained acid to the step (1) for leaching.
Comparative example 1
Compared with the embodiment 1, the acidification leaching and the corresponding evaporation concentration step in the step (2) are removed, concentrated sulfuric acid is directly added for roasting, and other conditions are not changed; the silicon removal rate after the treatment of the step (4) is 10.18 percent, the fluorine removal rate is 99.48 percent, and the final obtained carbon purity is 93.75 percent. It can be seen that if the phase transformation of the silicon dioxide and silicate in the waste cathode carbon block is not performed in advance, the removal of silicon and the deep purification of carbon materials are not facilitated.
Comparative example 2
Compared with the example 1, the step (2) adds the sulfuric acid solution, and then the mol ratio of Si and S in the slurry A is 1: 1, other conditions are unchanged; the silicon removal rate after the treatment of the step (4) is 20.21 percent, the fluorine removal rate is 99.50 percent, the finally obtained carbon purity is 94.84 percent, and too little acid addition is not beneficial to the removal of silicon so as to influence the carbon purity.
Comparative example 3
Compared with the example 1, the step (2) adds the sulfuric acid solution, and then the mol ratio of Si and S in the slurry A is 1: 5, other conditions are unchanged; the silicon removal rate after the treatment of the step (4) is 98.96 percent, the fluorine removal rate is 99.47 percent, and the final obtained carbon purity is 97.62 percent. It is found that an excessive amount of acid added does not improve the purity of the char, but increases the burden of the evaporation and concentration in the step (3).
Comparative example 4
Compared with the example 1, the acid concentration used in the step (2) is 10mol/L, and other conditions are not changed; after the treatment of the step (4), the silicon removal rate is 50.21%, the fluorine removal rate is 99.51%, and the purity of the finally obtained carbon is 95.75%, so that the high-concentration acid is not beneficial to the removal of silicon and the purification of carbon.
Comparative example 5
Compared with the example 1, the acid concentration used in the step (2) is 0.1mol/L, and other conditions are not changed; the silicon removal rate after the treatment in the step (4) is 40.58%, the fluorine removal rate is 99.21%, and the final obtained carbon purity is 95.21%. Too low an acid concentration is detrimental to the removal of silicon and thus affects carbon purity.
Comparative example 6
Compared with the example 1, the acidification leaching process in the step (2) is carried out under the condition of 90 ℃ and normal pressure, and other conditions are not changed; the silicon removal rate after the treatment of the step (4) is 29.12 percent, the fluorine removal rate is 99.39 percent, and the finally obtained carbon purity is 94.96 percent, so that the low temperature and the low pressure are not beneficial to the removal of silicon, thereby influencing the carbon purity.
Comparative example 7
Compared with the embodiment 1, the evaporation concentration process in the step (3) is removed, the slurry B is directly added with concentrated sulfuric acid for two-stage roasting, and other conditions are not changed; the silicon removal rate after the treatment in the step (4) is 49.87%, the fluorine removal rate is 80.53%, and the final purity of the obtained carbon is 95.39%. It can be seen that the removal, evaporation and concentration process is not favorable for removing silicon, thereby affecting the improvement of carbon purity.
Comparative example 8
Compared with the example 1, the step (3) evaporates and concentrates the slurry B until the water content is 15 percent by mass, and the other conditions are not changed; the silicon removal rate after the treatment in the step (4) is 80.32%, the fluorine removal rate is 90.31%, and the final purity of the obtained carbon is 96.54%. It can be seen that excessive moisture in slurry C is detrimental to the removal of silicon and thus affects the improvement of carbon purity.
Comparative example 9
Compared with the embodiment 1, the first-stage roasting process in the step (4) is removed, the second-stage roasting is directly carried out, and other conditions are not changed; the silicon removal rate after the treatment in the step (4) is 5.21%, the fluorine removal rate is 10.51%, and the final purity of the obtained carbon is 92.61%. It is seen that the removal of one stage of calcination is not only detrimental to the removal of silicon but also to the removal of fluorine, so that the carbon purity is difficult to improve, and the excessive fluorine volatilizes in the high-temperature calcination stage and seriously corrodes equipment.
Comparative example 10
Compared with the example 1, the first-stage roasting temperature in the step (4) is changed to 90 ℃, and other conditions are not changed; the silicon removal rate after the treatment of the step (4) is 9.31%, the fluorine removal rate is 15.89%, and the final obtained carbon purity is 92.93%. The low temperature is not only unfavorable for the removal of silicon but also unfavorable for the removal of fluorine, so that the carbon purity is difficult to improve, and the excessive fluorine volatilizes in the high-temperature calcination stage and seriously corrodes equipment.
Comparative example 11
Compared with the example 1, the roasting time in the step (4) is changed into 10 minutes, and other conditions are not changed; the silicon removal rate after the treatment of the step (4) is 11.23%, the fluorine removal rate is 30.21%, and the final purity of the obtained carbon is 93.28%. Therefore, the short calcination time is not only unfavorable for removing silicon but also unfavorable for removing fluorine, so that the carbon purity is difficult to improve, and the excessive fluorine volatilizes in the high-temperature calcination stage to seriously corrode equipment.
Comparative example 12
Compared with the embodiment 1, the second-stage roasting process is removed in the removing step (4), and the first-stage roasting product is directly used for high-temperature roasting; the silicon removal rate after the treatment of the step (4) is 98.48%, the fluorine removal rate is 99.27%, and the final purity of the obtained carbon is 97.59%. The two-stage roasting is omitted, which can lead a large amount of sulfuric acid which can be removed at low temperature to be decomposed and volatilized at high temperature, generate a large amount of high-temperature sulfur-containing flue gas and increase the burden of high-temperature flue gas treatment.
Comparative example 13
Comparing step (4) F, S with example 1, the molar ratio was 1: 0.5, other conditions are unchanged; the silicon removal rate after the treatment of the step (4) is 30.98 percent, the fluorine removal rate is 50.45 percent, and the finally obtained carbon purity is 94.01 percent. Too little acid is not only detrimental to the removal of silicon but also to the removal of fluorine, so that the carbon purity is difficult to improve, and the excessive fluorine volatilizes in the high-temperature calcination stage and seriously corrodes equipment.
Comparative example 14
Comparing step (4) F, S with example 1, the molar ratio was 1: 7.0, other conditions are not met; the silicon removal rate after the treatment in the step (4) is 98.91%, the fluorine removal rate is 99.63%, and the final carbon purity is 97.58%, which indicates that excessive acid cannot improve the carbon purity.
Comparative example 15
Compared with the embodiment 1, the high-temperature calcination time in the step (5) is changed to 1 hour, and other conditions are not changed; the silicon removal rate after the treatment in the step (4) is 98.79%, the fluorine removal rate is 99.53%, and the finally obtained carbon purity is 95.94%, so that the short calcination time is not beneficial to the effective volatilization and removal of ash in the calcined carbon, thereby affecting the carbon purity.
While the foregoing is directed to the preferred embodiment of the present invention, it will be appreciated by those skilled in the art that various changes may be made without departing from the principles of the invention, and it is intended that all such changes and modifications be considered as within the scope of the invention.
Claims (10)
1. A method for recovering waste cathode carbon blocks in aluminum electrolysis is characterized by comprising the following steps: the method comprises the following steps:
mixing the waste cathode carbon particles with a sulfuric acid solution to obtain a slurry A, and leaching to obtain a slurry B, wherein the concentration of the sulfuric acid solution is 0.5-8 mol/L; and (3) evaporating and concentrating the slurry B to obtain slurry C, adding concentrated sulfuric acid into the slurry C to obtain slurry D, carrying out primary roasting on the slurry D at 150-300 ℃, then carrying out secondary roasting at 300-600 ℃ to obtain roasted carbon, and roasting the roasted carbon to obtain purified carbon.
2. The method for recovering the aluminum electrolysis waste cathode carbon block as claimed in claim 1, wherein:
the concentration of the sulfuric acid solution is 1-3 mol/L;
in the slurry A, the molar ratio of Si: 1, S: 2.05 to 3.0.
3. The method for recovering the aluminum electrolysis waste cathode carbon block as claimed in claim 1, wherein:
the leaching is pressure leaching, the leaching temperature is 100-300 ℃, the leaching time is 1-10 hours, and the pressure is 0.1-9 MPa.
4. The method for recovering the aluminum electrolysis waste cathode carbon block as claimed in claim 1, wherein:
and (3) evaporating and concentrating the slurry B at 100-200 ℃ to obtain slurry C.
5. The method for recovering the aluminum electrolysis waste cathode carbon block as claimed in claim 1 or 4, wherein: in the slurry C, the mass fraction of water is less than 8%.
6. The method for recovering the aluminum electrolysis waste cathode carbon block as claimed in claim 1, wherein:
the concentration of the concentrated sulfuric acid is 17-18.4 mol/L;
in the slurry D, in terms of molar ratio, F: 1, S: 0.5 to 5.
7. The method for recovering the aluminum electrolysis waste cathode carbon block as claimed in claim 1, wherein:
the temperature of the first-stage roasting is 150-250 ℃, and the time of the first-stage roasting is 0.5-10 h;
the temperature of the second-stage roasting is 350-500 ℃, and the time of the second-stage roasting is 0.5-8 h.
8. The method for recovering the aluminum electrolysis waste cathode carbon block as claimed in claim 1, wherein:
recovering steam generated in the evaporation concentration process of the slurry B, absorbing smoke generated in the second-stage roasting process by using the steam recovered in the evaporation concentration process of the slurry B, and preparing acid liquor formed after absorption into sulfuric acid solution to be returned for leaching the waste cathode carbon particles;
and (3) absorbing and recovering fluorine from flue gas generated by the first-stage roasting by adopting an alumina dry method.
9. The method for recovering the aluminum electrolysis waste cathode carbon block as claimed in claim 1, wherein:
the calcining temperature is 1200-3000 ℃, and the calcining time is 0.5-20 h;
the calcination is carried out in an inert atmosphere, a reducing atmosphere or an atmosphere with an oxygen partial pressure of less than 1000 Pa.
10. The method for recovering the aluminum electrolysis waste cathode carbon block as claimed in claim 1 or 9, wherein:
calcining the calcined carbon at 1200-2200 ℃ for 4-10 h to obtain purified carbon; the obtained purified carbon is a carbon material with the purity of more than 97.5 percent;
calcining the calcined carbon at the temperature of 2200-3000 ℃ for 4-7 h to obtain purified carbon; the obtained purified carbon is graphite powder with the purity of more than 99 percent.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010062001.4A CN111170299B (en) | 2020-01-19 | 2020-01-19 | Method for recovering waste cathode carbon blocks from aluminum electrolysis |
| US17/764,561 US11697594B2 (en) | 2020-01-19 | 2021-01-16 | Method for recycling spent carbon cathode of aluminum electrolysis |
| PCT/CN2021/072343 WO2021143887A1 (en) | 2020-01-19 | 2021-01-16 | Method for recycling waste cathode carbon blocks of aluminum electrolysis |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010062001.4A CN111170299B (en) | 2020-01-19 | 2020-01-19 | Method for recovering waste cathode carbon blocks from aluminum electrolysis |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111170299A true CN111170299A (en) | 2020-05-19 |
| CN111170299B CN111170299B (en) | 2021-06-22 |
Family
ID=70646811
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010062001.4A Active CN111170299B (en) | 2020-01-19 | 2020-01-19 | Method for recovering waste cathode carbon blocks from aluminum electrolysis |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111170299B (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112265987A (en) * | 2020-09-24 | 2021-01-26 | 中南大学 | Combined treatment method of fluosilicic acid wastewater and waste lithium ion battery carbon slag |
| CN112322076A (en) * | 2020-11-04 | 2021-02-05 | 中南大学 | Method for preparing carbon black |
| WO2021143887A1 (en) * | 2020-01-19 | 2021-07-22 | 中南大学 | Method for recycling waste cathode carbon blocks of aluminum electrolysis |
| CN113415797A (en) * | 2021-06-16 | 2021-09-21 | 广西博世科环保科技股份有限公司 | Aluminum electrolytic cell waste cathode carbon block treatment process |
| CN114749465A (en) * | 2022-05-02 | 2022-07-15 | 郑州大学 | Method for purifying aluminum electrolysis waste cathode carbon and preparing porous carbon adsorbent |
| CN114751666A (en) * | 2022-04-27 | 2022-07-15 | 中国科学院青海盐湖研究所 | Method for preparing magnesium material by using waste aluminum electrolysis waste cathode carbon block as raw material |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59171563A (en) * | 1983-03-01 | 1984-09-28 | アルカン・インタ−ナシヨナル・リミテツド | Treatment of scrap lining material of electrolytic reducing cell |
| CN1320491A (en) * | 2001-02-28 | 2001-11-07 | 赵隆昌 | Process for recovering waste liner of aluminium electrolyzer |
| CN1785537A (en) * | 2005-11-28 | 2006-06-14 | 中国铝业股份有限公司 | Treatment method of aluminium electrolytic bath waste cathode carbon blook innocuousnes |
| CN105692676A (en) * | 2016-04-12 | 2016-06-22 | 郑州鸿跃环保科技有限公司 | Comprehensive treatment system for aluminum electrolytic cell waste residues |
| CN107282598A (en) * | 2017-07-03 | 2017-10-24 | 李立安 | A kind of aluminium cell discards the recoverying and utilizing method of cathode carbon pieces |
| CN107337191A (en) * | 2016-12-16 | 2017-11-10 | 贵阳铝镁设计研究院有限公司 | The method that carbon is extracted in the molten waste cathode carbon block from electrolytic cell of water-soluble combination acid |
| CN107662913A (en) * | 2017-09-30 | 2018-02-06 | 陈湘清 | A kind of aluminium electroloysis waste cathode carbon block processing and treating method |
| CN107904621A (en) * | 2017-11-09 | 2018-04-13 | 北京科技大学 | A kind of regeneration treating method of waste cathode of aluminum electrolytic cell carbon block |
| CN108728867A (en) * | 2018-06-19 | 2018-11-02 | 东北大学 | A kind of innoxious separation method of aluminium electroloysis waste cathode carbon block |
| CN110127649A (en) * | 2019-05-06 | 2019-08-16 | 广西纳保环境科技有限公司 | A kind of recoverying and utilizing method of electrolytic aluminium electrolytic tank waste and old cathode carbon block |
-
2020
- 2020-01-19 CN CN202010062001.4A patent/CN111170299B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59171563A (en) * | 1983-03-01 | 1984-09-28 | アルカン・インタ−ナシヨナル・リミテツド | Treatment of scrap lining material of electrolytic reducing cell |
| CN1320491A (en) * | 2001-02-28 | 2001-11-07 | 赵隆昌 | Process for recovering waste liner of aluminium electrolyzer |
| CN1785537A (en) * | 2005-11-28 | 2006-06-14 | 中国铝业股份有限公司 | Treatment method of aluminium electrolytic bath waste cathode carbon blook innocuousnes |
| CN105692676A (en) * | 2016-04-12 | 2016-06-22 | 郑州鸿跃环保科技有限公司 | Comprehensive treatment system for aluminum electrolytic cell waste residues |
| CN107337191A (en) * | 2016-12-16 | 2017-11-10 | 贵阳铝镁设计研究院有限公司 | The method that carbon is extracted in the molten waste cathode carbon block from electrolytic cell of water-soluble combination acid |
| CN107282598A (en) * | 2017-07-03 | 2017-10-24 | 李立安 | A kind of aluminium cell discards the recoverying and utilizing method of cathode carbon pieces |
| CN107662913A (en) * | 2017-09-30 | 2018-02-06 | 陈湘清 | A kind of aluminium electroloysis waste cathode carbon block processing and treating method |
| CN107904621A (en) * | 2017-11-09 | 2018-04-13 | 北京科技大学 | A kind of regeneration treating method of waste cathode of aluminum electrolytic cell carbon block |
| CN108728867A (en) * | 2018-06-19 | 2018-11-02 | 东北大学 | A kind of innoxious separation method of aluminium electroloysis waste cathode carbon block |
| CN110127649A (en) * | 2019-05-06 | 2019-08-16 | 广西纳保环境科技有限公司 | A kind of recoverying and utilizing method of electrolytic aluminium electrolytic tank waste and old cathode carbon block |
Non-Patent Citations (1)
| Title |
|---|
| 逯军正 等: "铝电解废阴极中氟化物浸提实验研究", 《硅酸盐通报》 * |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021143887A1 (en) * | 2020-01-19 | 2021-07-22 | 中南大学 | Method for recycling waste cathode carbon blocks of aluminum electrolysis |
| US11697594B2 (en) | 2020-01-19 | 2023-07-11 | Central South University | Method for recycling spent carbon cathode of aluminum electrolysis |
| CN112265987A (en) * | 2020-09-24 | 2021-01-26 | 中南大学 | Combined treatment method of fluosilicic acid wastewater and waste lithium ion battery carbon slag |
| CN112265987B (en) * | 2020-09-24 | 2022-10-04 | 中南大学 | Combined treatment method of fluosilicic acid wastewater and waste lithium ion battery carbon slag |
| CN112322076A (en) * | 2020-11-04 | 2021-02-05 | 中南大学 | Method for preparing carbon black |
| CN112322076B (en) * | 2020-11-04 | 2021-10-01 | 中南大学 | Method for preparing carbon black |
| CN113415797A (en) * | 2021-06-16 | 2021-09-21 | 广西博世科环保科技股份有限公司 | Aluminum electrolytic cell waste cathode carbon block treatment process |
| CN114751666A (en) * | 2022-04-27 | 2022-07-15 | 中国科学院青海盐湖研究所 | Method for preparing magnesium material by using waste aluminum electrolysis waste cathode carbon block as raw material |
| CN114751666B (en) * | 2022-04-27 | 2023-03-10 | 中国科学院青海盐湖研究所 | Method for preparing magnesium material by using waste aluminum electrolysis waste cathode carbon block as raw material |
| CN114749465A (en) * | 2022-05-02 | 2022-07-15 | 郑州大学 | Method for purifying aluminum electrolysis waste cathode carbon and preparing porous carbon adsorbent |
| CN114749465B (en) * | 2022-05-02 | 2023-07-11 | 郑州大学 | Method for purifying aluminum electrolysis waste cathode carbon and preparing porous carbon adsorbent |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111170299B (en) | 2021-06-22 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111170299B (en) | Method for recovering waste cathode carbon blocks from aluminum electrolysis | |
| CN111232947B (en) | Method for recovering waste cathode carbon blocks in aluminum electrolysis | |
| AU2009259366B2 (en) | Processing method for recovering iron oxide and hydrochloric acid | |
| CN115156238B (en) | Comprehensive recycling method for aluminum electrolysis waste cathode carbon blocks and application thereof | |
| CN108163812B (en) | Preparation method of hydrogen fluoride and preparation method of hydrofluoric acid | |
| CN1290651A (en) | Method for preparing sulfur with recovered smelting smoke SO2 | |
| US11697594B2 (en) | Method for recycling spent carbon cathode of aluminum electrolysis | |
| CN112897466A (en) | Method for producing anhydrous hydrogen fluoride by using fluosilicic acid in phosphoric acid | |
| CN115818676B (en) | Method for extracting lithium and recovering fluorine by roasting lithium-containing waste aluminum electrolyte at low temperature | |
| CN114717610B (en) | Method for reducing potassium content in aluminum electrolysis fluorine-carrying aluminum oxide | |
| CN111270092A (en) | Method for decomposing mixed rare earth ore | |
| CN111196609B (en) | Method for recovering waste carbon material from aluminum electrolysis | |
| CN209161488U (en) | A kind of system of sulfur gas reduction Waste Sulfuric Acid sulfur dioxide liquid and sulfuric acid | |
| CN115124019B (en) | Method for preparing silicon-carbon material by utilizing fluosilicic acid waste | |
| CN109796034B (en) | Preparation method of cryolite | |
| CN115764033A (en) | Battery black powder recovery method and device | |
| CN111217356B (en) | Method for recovering porous carbon from aluminum electrolysis anode carbon slag | |
| CN110028042B (en) | Method for recycling waste cathode carbon blocks of electrolytic aluminum electrolysis cell | |
| CN113816339A (en) | Method for preparing anhydrous hydrogen fluoride from sodium fluoride | |
| CA2365855C (en) | Method of treating spent potliner material from aluminum reduction cells | |
| CN112342392A (en) | Method for respectively recovering titanium, tungsten and vanadium from waste denitration catalyst | |
| CN114349043A (en) | Method for recovering lead oxide from waste lead paste | |
| CN110330019B (en) | Efficient and environment-friendly comprehensive utilization method of yellow phosphorus slag and tail gas | |
| CN112225179A (en) | Process and device for preparing hydrogen fluoride from fluorite | |
| CN115786990A (en) | Closed loop recycling of SO in aluminum electrolysis flue gas 2 And CO 2 Method (2) |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |