CN109930174B - Method for lithium removal, purification and lithium recovery of aluminum electrolyte - Google Patents
Method for lithium removal, purification and lithium recovery of aluminum electrolyte Download PDFInfo
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- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 99
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 99
- 239000003792 electrolyte Substances 0.000 title claims abstract description 98
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 72
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 72
- 238000000034 method Methods 0.000 title claims abstract description 45
- 238000000746 purification Methods 0.000 title abstract description 27
- 238000011084 recovery Methods 0.000 title description 10
- 239000000706 filtrate Substances 0.000 claims abstract description 92
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 20
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 20
- 239000000047 product Substances 0.000 claims abstract description 12
- 238000001704 evaporation Methods 0.000 claims abstract description 10
- 230000003472 neutralizing effect Effects 0.000 claims abstract description 7
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 claims description 44
- 238000001914 filtration Methods 0.000 claims description 42
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 24
- 235000010344 sodium nitrate Nutrition 0.000 claims description 22
- 239000004317 sodium nitrate Substances 0.000 claims description 22
- 238000001816 cooling Methods 0.000 claims description 20
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 19
- 229910017604 nitric acid Inorganic materials 0.000 claims description 19
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 18
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 18
- 238000005406 washing Methods 0.000 claims description 18
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 17
- 238000001035 drying Methods 0.000 claims description 17
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 16
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- 229910001634 calcium fluoride Inorganic materials 0.000 claims description 14
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 12
- 239000002244 precipitate Substances 0.000 claims description 11
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 10
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 9
- 239000007789 gas Substances 0.000 claims description 8
- 229910000040 hydrogen fluoride Inorganic materials 0.000 claims description 8
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 8
- 239000000126 substance Substances 0.000 claims description 8
- 238000000498 ball milling Methods 0.000 claims description 7
- 239000011259 mixed solution Substances 0.000 claims description 7
- 238000003756 stirring Methods 0.000 claims description 7
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 claims description 6
- 239000006227 byproduct Substances 0.000 claims description 6
- 229910001424 calcium ion Inorganic materials 0.000 claims description 6
- QXDMQSPYEZFLGF-UHFFFAOYSA-L calcium oxalate Chemical compound [Ca+2].[O-]C(=O)C([O-])=O QXDMQSPYEZFLGF-UHFFFAOYSA-L 0.000 claims description 6
- 235000006408 oxalic acid Nutrition 0.000 claims description 6
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 5
- 239000000920 calcium hydroxide Substances 0.000 claims description 5
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 5
- -1 fluoride ions Chemical class 0.000 claims description 4
- 230000007935 neutral effect Effects 0.000 claims description 4
- 229910002651 NO3 Inorganic materials 0.000 claims description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 2
- 159000000007 calcium salts Chemical class 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 238000012216 screening Methods 0.000 claims description 2
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims 3
- 238000004064 recycling Methods 0.000 abstract description 11
- 238000004519 manufacturing process Methods 0.000 abstract description 9
- 239000002994 raw material Substances 0.000 abstract description 6
- 230000008901 benefit Effects 0.000 abstract description 5
- 238000005265 energy consumption Methods 0.000 abstract description 4
- 230000007774 longterm Effects 0.000 abstract description 2
- 239000012535 impurity Substances 0.000 abstract 1
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 description 38
- 238000002441 X-ray diffraction Methods 0.000 description 22
- 229910001610 cryolite Inorganic materials 0.000 description 13
- 238000010438 heat treatment Methods 0.000 description 9
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 9
- 229910052808 lithium carbonate Inorganic materials 0.000 description 9
- 238000001228 spectrum Methods 0.000 description 9
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 8
- 238000005868 electrolysis reaction Methods 0.000 description 5
- 239000003337 fertilizer Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 238000005303 weighing Methods 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
- 235000010333 potassium nitrate Nutrition 0.000 description 4
- 239000004323 potassium nitrate Substances 0.000 description 4
- 238000009833 condensation Methods 0.000 description 3
- 230000005494 condensation Effects 0.000 description 3
- 238000002386 leaching Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229910052700 potassium Inorganic materials 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- PQVSTLUFSYVLTO-UHFFFAOYSA-N ethyl n-ethoxycarbonylcarbamate Chemical compound CCOC(=O)NC(=O)OCC PQVSTLUFSYVLTO-UHFFFAOYSA-N 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 239000011737 fluorine Substances 0.000 description 2
- 229910052731 fluorine Inorganic materials 0.000 description 2
- AMXOYNBUYSYVKV-UHFFFAOYSA-M lithium bromide Chemical compound [Li+].[Br-] AMXOYNBUYSYVKV-UHFFFAOYSA-M 0.000 description 2
- GLXDVVHUTZTUQK-UHFFFAOYSA-M lithium hydroxide monohydrate Substances [Li+].O.[OH-] GLXDVVHUTZTUQK-UHFFFAOYSA-M 0.000 description 2
- 229940040692 lithium hydroxide monohydrate Drugs 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 229910001148 Al-Li alloy Inorganic materials 0.000 description 1
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- JFBZPFYRPYOZCQ-UHFFFAOYSA-N [Li].[Al] Chemical compound [Li].[Al] JFBZPFYRPYOZCQ-UHFFFAOYSA-N 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000006115 defluorination reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000001989 lithium alloy Substances 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
Images
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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
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Secondary Cells (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The invention discloses a method for removing lithium, purifying and recovering lithium from an aluminum electrolyte, which comprises the following steps: (1) lithium removal and purification of the aluminum electrolyte; (2) the recycling of the lithium removed specifically comprises: evaporating and concentrating the filtrate, neutralizing, removing impurities, and recovering lithium to prepare the lithium salt. Aims to solve the problem of energy consumption increase caused by the enrichment of the content of electrolyte lithium in the long-term operation process of the electrolytic cell in the aluminum industry. The content of lithium in the aluminum electrolyte treated by the method is not more than 0.5 percent, and the aluminum electrolyte can be returned to an electrolytic cell for recycling; the lithium removed can be recycled. The high-added-value lithium salt product prepared by the method opens up new lithium resources on one hand, relieves the demand condition of the current market on high-end lithium products on the other hand, promotes the technical progress of China in new energy industry and high-end lithium application industry, and has remarkable social benefit; the raw materials have wide sources, the comprehensive cost is lower, the process is simple and easy to implement, the production process is clean and environment-friendly, and good economic and social benefits are achieved.
Description
Technical Field
The invention relates to the technical field of aluminum electrolysis smelting, in particular to a method for removing lithium, purifying and recovering lithium from aluminum electrolyte.
Background
In recent years, with the rapid development of the electrolytic aluminum industry, the demand for alumina raw materials has increasedMore and more, the domestic alumina contains L i to different degrees due to different mineral sources and preparation processes2And O. Such lithium-containing alumina raw materials are fed into an electrolytic cell, and a lithium salt is introduced into the aluminum electrolytic cell together therewith and continuously accumulated in the electrolyte. And along with the prolonging of the age of the electrolytic cell, lithium is gradually enriched, and the content of lithium fluoride can reach 6-10%. In an aluminum electrolyte system, when the content of lithium fluoride is 2-3%, the primary crystal temperature of the electrolyte can be reduced, and the energy consumption is reduced; however, the electrolyte system with high lithium salt content not only reduces the solubility of alumina in the electrolyte, but also causes high superheat degree of the electrolyte, increases energy consumption, shortens the service life of the electrolytic cell, and directly influences the economic efficiency of the electrolytic aluminum industry. Therefore, how to reduce the lithium content of the aluminum electrolyte in the electrolytic cell is a technical problem to be solved urgently in the electrolytic aluminum industry of China.
In the aluminum electrolysis process, in order to ensure that the electrolytic cell normally and stably operates, the electrolyte level and the total amount of the electrolytic cell must be controlled, the electrolytic cell which operates for a period of time usually needs to draw out excessive electrolyte to control the balance of the electrolytic cell, and the excessive electrolyte is actually a byproduct of an aluminum electrolysis plant. At present, domestic enterprises pay little attention to the resource, most enterprises store a large amount of electrolytes, and the utilization level of the electrolytes has a large gap with foreign countries.
With the development of industrial technology, the industrial application field of lithium salts, such as lithium batteries, aluminum lithium alloys, lithium bromide air conditioners, atomic energy industry, organic synthesis and the like, is continuously expanded, the demand for lithium salts is rapidly developed, particularly in the aspect of chemical energy, the lithium salts are used as basic materials of new energy, the demand is short, the price is high, and if lithium-containing aluminum electrolyte can be used as lithium salt resources to extract the lithium salts, the lithium salts have important significance for the development of lithium salt industry in China.
In conclusion, how to extract and recover lithium element in the aluminum electrolyte by adopting a proper process has great significance in eliminating the influence of the lithium element on aluminum electrolysis production and preparing a lithium salt product with high added value.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a method for lithium removal, purification and lithium recovery of an aluminum electrolyte, which can effectively extract lithium element in the electrolyte, obtain an industrial electrolyte with high purity and suitable for aluminum electrolyte production, and reduce the energy consumption of electrolytic aluminum production; and meanwhile, the lithium salt product with high purity is prepared, the comprehensive cost is lower, and the process is simple and feasible.
In order to solve the technical problems, the invention adopts the following technical scheme:
a method for lithium removal and purification of an aluminum electrolyte is designed, and comprises the following steps:
(1) crushing and screening an aluminum electrolyte, wherein the main component of the aluminum electrolyte is cryolite Na3AlF6Calcium fluoride CaF2Lithium fluoride L iF, etc.;
(2) slowly adding aluminum electrolyte into 0.5-12 mol/L nitric acid, wherein the ratio of the aluminum electrolyte to the nitric acid is 1 g: 1m L-40 m L, and stirring and reacting for 0.5-10 h at the temperature of 60-120 ℃;
(3) after the reaction is finished, naturally cooling the mixed solution after the reaction to room temperature, filtering, respectively collecting primary filtrate, filter residue and hydrogen fluoride gas, washing the filter residue to be neutral, drying to obtain the lithium-removed and purified aluminum electrolyte, wherein after the lithium-removed and purified aluminum electrolyte is obtained, the lithium content of the aluminum electrolyte is not more than 0.5 percent, and the aluminum electrolyte can be returned to an electrolytic bath of an aluminum electrolysis plant to be recycled as the aluminum electrolyte;
in this step, the main reaction equation is:
preferably, in the step (1), the aluminum electrolyte is ground by ball milling and then sieved by a 50-200 mesh sieve.
Preferably, in the step (1), the concentration of the nitric acid is 2-6 mol/L.
Preferably, in the step (2), the reaction time is 0.5-5 h.
Preferably, in the step (3), hydrogen fluoride gas is generated in the lithium removal and purification of the aluminum electrolyte, part of the hydrogen fluoride gas is dissolved in the filtrate to form hydrofluoric acid, the hydrogen fluoride gas is volatile, the hydrogen fluoride gas can be enriched by adopting a condensation reflux mode, and the hydrogen fluoride gas is subjected to harmless treatment by adopting alkali liquor and then is discharged after reaching the standard.
In the above-mentioned lithium removal and purification of the aluminum electrolyte, sulfuric acid is used to leach the aluminum electrolyte in the prior art, but researches have found that the leaching method dissolves cryolite needed to be present in the electrolyte while leaching lithium salt, destroys the structure of the aluminum electrolyte, and the sulfuric acid medium can not be recycled. Through a large amount of experimental research and long-term production practical experience, the invention optimally selects the proper nitric acid liquid with a low concentration range to carry out lithium removal and purification on the aluminum electrolyte, basically does not damage the structure of the aluminum electrolyte while leaching lithium salt, and can recycle part of nitric acid in the process of concentrating primary filtrate.
The invention also provides a method for recovering lithium from the aluminum electrolyte, which mainly comprises the following steps:
(1) lithium extracted from the filtrate after lithium removal and purification of the aluminum electrolyte is used for extracting lithium element, the concentration of the lithium element after evaporation and concentration of the primary filtrate is 3-8 g/L, the lithium element is naturally cooled to room temperature and filtered to obtain secondary filter residue and secondary filtrate, and the secondary filter residue is dried to obtain a byproduct sodium nitrate;
(2) adding an alkaline substance into the secondary filtrate to adjust the pH value of the secondary filtrate to 6-7, naturally cooling to room temperature, filtering to obtain third filter residue and third filtrate, and drying the third filter residue to obtain a byproduct nitrate;
(3) adding soluble calcium salt or calcium hydroxide into the third filtrate to remove fluoride ions in the filtrate, filtering to obtain fourth filtrate and calcium fluoride precipitate, adding oxalic acid into the fourth filtrate to precipitate redundant calcium ions, and filtering to obtain fifth filtrate and calcium oxalate precipitate;
in order to ensure the high purity of the prepared lithium salt product, the filtrate needs to be subjected to defluorination treatment;
(4) recovering lithium from the filtrate obtained in the fifth step by adopting solid sodium carbonate or potassium carbonate, adjusting the pH value of the filtrate to 8-12, filtering, neutralizing the obtained filtrate to be neutral, and using the filtrate as a fertilizer due to the N, K element; and washing and drying the precipitate obtained by filtering to obtain the high-purity lithium salt product lithium carbonate.
Preferably, in the process of evaporating and concentrating the primary filtrate, part of nitric acid is volatilized and is recovered through condensation, and part of nitric acid solution can be recycled.
Preferably, in the step (2), the alkaline substance is at least one of potassium carbonate, potassium hydroxide, sodium carbonate and sodium hydroxide.
Preferably, lithium is recovered from the filtrate for five times by adopting solid sodium hydroxide or potassium hydroxide, the pH value of the filtrate is adjusted to 8-12, and the precipitate obtained by filtering is washed and dried to obtain the high-purity lithium salt product, namely the lithium hydroxide monohydrate.
Compared with the prior art, the invention has the beneficial technical effects that:
1. the purification method can reduce the lithium content of the aluminum electrolyte in the electrolytic aluminum industry, the lithium content of the purified aluminum electrolyte is not more than 0.5 percent, the aluminum electrolyte obtained by lithium removal and purification can be recycled in the electrolytic aluminum industry, the stable and balanced operation of the electrolytic cell is realized, the method solves the technical problem which puzzles the production in the electrolytic aluminum industry at present, improves the labor efficiency of the electrolytic aluminum production, saves energy, reduces consumption and production cost.
2. The recovery method can prepare the high-added-value lithium salt product, opens up new lithium resources on one hand, relieves the demand condition of the current market on high-end lithium products on the other hand, promotes the technical progress of China in new energy industry and high-end lithium application industry, and has remarkable social benefit.
3. The method realizes the lithium removal purification of the aluminum electrolyte and the recovery of lithium to obtain a byproduct with high added value, has no emission of toxic and harmful substances, and has clean, environment-friendly and sustainable production process.
4. The invention has the advantages of wide raw material source, low comprehensive cost, simple and easy process and good economic and social benefits.
Drawings
FIG. 1 is a process flow diagram of a method for delithiating, purifying and recovering lithium from an aluminum electrolyte according to the present invention;
FIG. 2 is a sodium nitrate XRD spectrum of the method for delithiating, purifying and recovering lithium from an aluminum electrolyte according to the present invention;
FIG. 3 is a XRD (X-ray diffraction) spectrum of lithium carbonate in the method for removing lithium, purifying and recovering lithium from the aluminum electrolyte.
Detailed Description
The following examples are given to illustrate specific embodiments of the present invention, but are not intended to limit the scope of the present invention in any way. The instruments and devices referred to in the following examples are conventional instruments and devices unless otherwise specified; the industrial raw materials are all conventional industrial raw materials which are sold on the market, if not specifically mentioned.
Example 1
The process flow of the method for lithium removal, purification and lithium recovery of the aluminum electrolyte in the embodiment is shown in fig. 1, and specifically comprises the following steps:
step 1: lithium removal and purification of aluminum electrolyte
(1) Ball milling and crushing the aluminum electrolyte containing lithium element, wherein the main component of the aluminum electrolyte is cryolite Na3AlF6Calcium fluoride CaF2And L iF, wherein the content of L iF is 6.5 percent, and the lithium fluoride is sieved by a sieve of 50 to 200 meshes;
(2) weighing 30g of 100-mesh aluminum electrolyte containing 6.5 percent of lithium fluoride L iF, slowly adding the weighed material into 110m L nitric acid with the concentration of 2.5 mol/L, and stirring for 5 hours at the temperature of 70 ℃;
(3) cooling the mixed solution after the reaction to room temperature under natural conditions, filtering, washing the filter residue for multiple times until the pH value of the final washing solution is 7 to obtain primary filtrate and primary filter residue, wherein the primary filtrate is 350m L, the primary filter residue is dried and has the weight of 26.3g, and the content of lithium fluoride in the aluminum electrolyte is 0.75% after purification;
step 2: recycling of the extracted lithium
(1) Evaporating and concentrating the primary filtrate of 350m L obtained in the step 1 until the concentration of lithium element is 3.5 g/L, volatilizing part of nitric acid in the evaporation and concentration process, recycling the nitric acid through condensation, naturally cooling to room temperature, and filtering to obtain secondary filtrate and secondary filter residue, wherein the secondary filter residue is sodium nitrate, the XRD (X-ray diffraction) spectrum of the sodium nitrate is shown in figure 2, and the drying is 0.8 g;
(2) adjusting the pH value of the secondary filtrate to 7 by adopting sodium carbonate, consuming 20.5g of sodium carbonate, cooling and filtering to obtain a tertiary filtrate and filter residue sodium nitrate, wherein the XRD (X-ray diffraction) spectrum of the sodium nitrate is shown in figure 2, and the filter residue sodium nitrate is dried to be 2.5 g;
(3) adding 0.7g of calcium hydroxide into the third filtrate to precipitate fluoride ions, filtering to obtain a fourth filtrate, adding 0.3g of oxalic acid to precipitate redundant calcium ions, and filtering to obtain a fifth filtrate and calcium oxalate;
(4) adding 3g sodium carbonate into the fifth filtrate under heating, adjusting pH to 9, heating the filtrate to boil, reacting for 30min, heat filtering, neutralizing the filtrate to neutrality, containing N element, and using as fertilizer, washing the precipitate, and drying to obtain 0.8g lithium carbonate L i2CO3The XRD pattern of the lithium carbonate is shown in figure 3, and the purity is 99.5%.
Example 2
The process flow of the method for lithium removal, purification and lithium recovery of the aluminum electrolyte in the embodiment is shown in fig. 1, and specifically comprises the following steps:
step 1: lithium removal and purification of aluminum electrolyte
(1) Ball milling and crushing the aluminum electrolyte containing lithium element, wherein the main component of the aluminum electrolyte is cryolite Na3AlF6Calcium fluoride CaF2And L iF, wherein the content of L iF is 8.5 percent, and the lithium fluoride is sieved by a sieve of 50 to 200 meshes;
(2) weighing 100g of 200-mesh aluminum electrolyte containing 8.5 percent of lithium fluoride L iF, slowly adding the aluminum electrolyte into 1000m of nitric acid L with the concentration of 7 mol/L, and stirring for 3 hours at the temperature of 115 ℃;
(3) naturally cooling the mixed solution after the reaction to room temperature, filtering, washing the filter residue for multiple times until the pH of the final washing solution is 7 to obtain primary filtrate and primary filter residue, wherein the primary filtrate is 2230m L, the primary filter residue is dried and has the weight of 80g, and after purification, the content of lithium fluoride L iF in the aluminum electrolyte is 0.35%;
step 2: recycling of the extracted lithium
(1) Evaporating and concentrating the 2230m L primary filtrate obtained in the step 1 until the concentration of lithium element is 8 g/L, volatilizing part of nitric acid in the concentration process, condensing, recycling, cooling to room temperature, filtering to obtain secondary filtrate and secondary filter residue, wherein the secondary filter residue is sodium nitrate, the XRD (X-ray diffraction) spectrum of the sodium nitrate is shown in figure 2, and drying to be 3.5 g;
(2) adjusting the pH value of the secondary filtrate to 7 by adopting sodium carbonate, consuming 68.7g of sodium carbonate, cooling and filtering to obtain a tertiary filtrate and filter residue sodium nitrate, wherein the XRD (X-ray diffraction) spectrum of the sodium nitrate is shown in figure 2, and the filter residue sodium nitrate is dried to be 12 g;
(3) adding 3.2g of calcium chloride into the third filtrate to precipitate fluorinion, filtering to obtain fourth filtrate, adding 2g of oxalic acid to precipitate redundant calcium ion, and filtering to obtain fifth filtrate and calcium oxalate;
(4) adding 10g sodium hydroxide into the fifth filtrate under heating, adjusting pH to 12, heating the filtrate to boiling, reacting for 45min, heat filtering, neutralizing the filtrate to neutrality, containing N element, and using as fertilizer, washing the precipitate, and drying to obtain 10g lithium hydroxide monohydrate L iOH. H2O, purity of 99.5%.
Example 3
The process flow of the method for lithium removal, purification and lithium recovery of the aluminum electrolyte in the embodiment is shown in fig. 1, and specifically comprises the following steps:
step 1: lithium removal and purification of aluminum electrolyte
(1) Carrying out ball milling crushing on the aluminum electrolyte containing lithium element, wherein the aluminum electrolyte comprises the following main components: cryolite Na3AlF6Calcium fluoride CaF2And L iF, wherein the content of L iF is 7.5 percent, and the lithium fluoride is sieved by a sieve of 50 to 200 meshes;
(2) weighing 20g of 50-mesh aluminum electrolyte containing 7.5 percent of lithium fluoride L iF, slowly adding the aluminum electrolyte into 400m L nitric acid with the concentration of 12 mol/L, and stirring for 9h at 70 ℃;
(3) naturally cooling the mixed solution after the reaction to room temperature, filtering, washing the filter residue for multiple times until the pH value of the final washing solution is 7 to obtain primary filtrate and primary filter residue, wherein the primary filtrate is 750m L, the primary filter residue is dried and has the weight of 16.5g, and after purification, the content of lithium fluoride L iF in the aluminum electrolyte is 1.5%;
step 2: recycling of the extracted lithium
(1) Evaporating and concentrating the primary 750m L filtrate obtained in the step 1 until the concentration of lithium element is 6 g/L, volatilizing part of nitric acid in the concentration process, condensing, recycling, cooling to room temperature, filtering to obtain secondary filtrate and secondary filter residue, wherein the secondary filter residue is sodium nitrate, the XRD (X-ray diffraction) spectrum of the sodium nitrate is shown in figure 2, and the drying amount is 0.5 g;
(2) regulating the pH value of the secondary filtrate to 7 by adopting potassium carbonate, consuming 12.5g of potassium carbonate, cooling, and filtering to obtain a tertiary filtrate and filter residue potassium nitrate, wherein the filter residue potassium nitrate is dried to be 1.5 g;
(3) adding 0.62g of calcium hydroxide into the third filtrate to precipitate fluorinion, filtering to obtain fourth filtrate, adding 0.18g of oxalic acid to precipitate redundant calcium ion, and filtering to obtain fifth filtrate and calcium oxalate;
(4) adding 3g potassium carbonate into the fifth filtrate under heating, adjusting pH to 9, heating the filtrate to boil, reacting for 30min, heat filtering, neutralizing the filtrate to neutrality, containing N, K element, and using as fertilizer, washing the precipitate, and drying to obtain 0.76g lithium carbonate L i2CO3The XRD pattern of the lithium carbonate is shown in figure 3, and the purity is 99.7%.
Example 4
The process flow of the method for lithium removal, purification and lithium recovery of the aluminum electrolyte in the embodiment is shown in fig. 1, and specifically comprises the following steps:
step 1: lithium removal and purification of aluminum electrolyte
(1) Ball-milling and crushing the aluminum electrolyte containing lithium element, wherein the main components of the aluminum electrolyte comprise cryolite Na3AlF6, calcium fluoride CaF2, lithium fluoride L iF and the like, wherein the content of the lithium fluoride L iF is 9.5 percent, and the aluminum electrolyte is sieved by a sieve of 50-200 meshes;
(2) weighing 60g of 180-mesh aluminum electrolyte containing 9.5% of lithium fluoride, slowly adding the weighed aluminum electrolyte into nitric acid with the concentration of 300m L being 1 mol/L, and stirring for 2h at the temperature of 80 ℃;
(3) naturally cooling the mixed solution after the reaction to room temperature, filtering, washing the filter residue for multiple times until the pH of the final washing solution is 7 to obtain primary filtrate and primary filter residue, wherein the primary filtrate is 620m L, the primary filter residue is dried, the weight of the primary filter residue is 51.3g, and the content of lithium fluoride L iF in the aluminum electrolyte is 1.1% after purification;
step 2: recycling of the extracted lithium
(1) Evaporating and concentrating the 620m L primary filtrate obtained in the step 1 until the concentration of lithium element is 4.7 g/L, volatilizing part of nitric acid in the concentration process, condensing, recycling, cooling to room temperature, filtering to obtain secondary filtrate and secondary filter residue, wherein the secondary filter residue is sodium nitrate, the XRD (X-ray diffraction) spectrum of the sodium nitrate is shown in figure 2, and drying to be 1.3 g;
(2) adjusting the pH value of the secondary filtrate to 7 by adopting potassium hydroxide, consuming 26.8g of potassium hydroxide, cooling and filtering to obtain tertiary filtrate and filter residue potassium nitrate, and drying the filter residue potassium nitrate to 8 g;
(3) adding 1.5g of calcium hydroxide into the third filtrate to precipitate fluorinion, filtering to obtain fourth filtrate, adding 0.45g of oxalic acid to precipitate redundant calcium ion, and filtering to obtain fifth filtrate and calcium oxalate;
(4) adding 3g potassium carbonate into the fifth filtrate under heating, adjusting pH to 9, heating the filtrate to boil, reacting for 30min, heat filtering, neutralizing the filtrate to neutrality, containing N, K element, and using as fertilizer, washing the precipitate, and drying to obtain 0.8g lithium carbonate L i2CO3The XRD pattern of the lithium carbonate is shown in figure 3, and the purity is 99.5%.
Comparative example
The method for lithium removal, purification and lithium recovery of the aluminum electrolyte in the comparative example specifically comprises the following steps:
step 1: lithium removal and purification of aluminum electrolyte
(1) Carrying out ball milling crushing on the aluminum electrolyte containing lithium element, wherein the aluminum electrolyte comprises the following main components: cryolite Na3AlF6Calcium fluoride CaF2And L iF, wherein the content of L iF is 8 percent, and the lithium fluoride is sieved by a 50-200 mesh sieve;
(2) weighing 40g of 150-mesh aluminum electrolyte containing 8% of lithium fluoride L iF, slowly adding the aluminum electrolyte into nitric acid with the concentration of 650m L of 0.5 mol/L, and stirring for 0.5h at the temperature of 110 ℃;
(3) and naturally cooling the mixed solution after the reaction to room temperature, filtering, washing for many times until the pH value of the filter residue is 7 to obtain primary filtrate and primary filter residue, wherein the primary filtrate is 1000m L, the primary filter residue is dried, the weight is 35.7g, and the content of lithium fluoride L iF in the aluminum electrolyte is 1.65% after purification.
Step 2: recycling of the extracted lithium
(1) Evaporating and concentrating the primary filtrate 1000m L obtained in the step 1 until the concentration of lithium element is 7 g/L, cooling and filtering to obtain secondary filtrate and secondary filter residue, wherein the secondary filter residue is sodium nitrate, the XRD (X-ray diffraction) spectrum of the sodium nitrate is shown in figure 2, and the secondary filtrate is dried to be 2.6 g;
(2) adjusting the pH value of the secondary filtrate to 7 by adopting sodium carbonate, consuming 20.5g of sodium carbonate, cooling and filtering to obtain a tertiary filtrate and filter residue sodium nitrate, wherein the XRD (X-ray diffraction) pattern of the sodium nitrate is shown in figure 2, and the filter residue sodium nitrate is dried to be 2.5 g;
(3) directly adding 5g of solid sodium carbonate into the third filtrate without removing fluorine, adjusting the pH value to 9, heating to boil, reacting for 50min, carrying out heat filtration, washing and drying to obtain 1.5g of lithium carbonate L i2CO3The purity was 85.7%, with a fluorine content of 12.5%.
While the present invention has been described in detail with reference to the embodiments and the accompanying drawings, it will be understood by those skilled in the art that various changes in the specific parameters and equivalents of the materials thereof may be made without departing from the spirit of the invention, and thus, it is intended that all of the embodiments and equivalents thereof form a plurality of common variations of the invention.
Claims (6)
1. A method of recovering lithium from an aluminum electrolyte, comprising the steps of:
(1) crushing and screening the aluminum electrolyte to be treated;
(2) slowly adding aluminum electrolyte into 2-6 mol/L nitric acid, wherein the adding proportion relation of the aluminum electrolyte and the nitric acid is 1 g: 1m L-40 m L, and stirring and reacting at 40-120 ℃ for 0.5-10 h;
(3) after the reaction is finished, naturally cooling the mixed solution after the reaction to room temperature, filtering, respectively collecting primary filtrate, filter residue and hydrogen fluoride gas, washing the filter residue to be neutral, and drying to obtain the product;
(4) evaporating the filtrate obtained in the step (3), concentrating the lithium element to a concentration of 3-8 g/L, naturally cooling to room temperature, filtering to obtain secondary filter residue and secondary filtrate, and drying the secondary filter residue to obtain a byproduct sodium nitrate;
(5) adjusting the pH value of the secondary filtrate to 6-7 by using an alkaline substance, naturally cooling and filtering to obtain third filter residue and third filtrate, and drying the third filter residue to obtain a byproduct nitrate;
(6) adding soluble calcium salt or calcium hydroxide into the third filtrate to remove fluoride ions in the filtrate, filtering to obtain fourth filtrate and calcium fluoride precipitate, adding oxalic acid into the fourth filtrate to precipitate redundant calcium ions, and filtering to obtain fifth filtrate and calcium oxalate precipitate;
(7) and adding an alkaline substance into the fifth filtrate, adjusting the pH value of the fifth filtrate to 8-12, filtering, neutralizing the filtrate to be neutral, washing and drying precipitates obtained by filtering to obtain a high-purity lithium salt product or/and a lithium hydroxide product.
2. The method for recovering lithium from the aluminum electrolyte according to claim 1, wherein in the step (1), the aluminum electrolyte to be treated is subjected to ball milling and crushing, and then is sieved by a 50-200-mesh sieve.
3. The method for recovering lithium from aluminum electrolyte according to claim 1, wherein the reaction time in the step (2) is 0.5-5 h.
4. The method for recovering lithium from aluminum electrolyte according to claim 1, further comprising a step of subjecting the hydrogen fluoride gas to a harmless treatment in step (3).
5. The method for recovering lithium from aluminum electrolyte according to claim 1, wherein in the step (5), the alkaline substance is at least one of potassium carbonate, potassium hydroxide, sodium carbonate and sodium hydroxide.
6. The method for recovering lithium from aluminum electrolyte according to claim 1, wherein in the step (7), the alkaline substance is at least one of potassium carbonate, potassium hydroxide, sodium carbonate and sodium hydroxide.
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| CN114934195A (en) * | 2022-06-20 | 2022-08-23 | 中国铝业股份有限公司 | Lithium salt recovery method and recovery equipment for aluminum electrolysis waste |
| CN115216630B (en) * | 2022-07-19 | 2023-11-14 | 中南大学 | Recycling treatment method of waste lithium-containing aluminum electrolyte |
| CN115246651B (en) * | 2022-08-12 | 2023-03-17 | 广州天赐高新材料股份有限公司 | Method for preparing lithium carbonate by recovering fluorine-containing lithium tailings |
| CN115959692B (en) * | 2023-01-03 | 2024-03-12 | 中铝郑州有色金属研究院有限公司 | Method for extracting lithium sodium potassium fluoroaluminate from solid volatile matters of aluminum electrolysis cell |
| CN116426758B (en) * | 2023-05-12 | 2023-12-05 | 中铝郑州有色金属研究院有限公司 | Purification method and system for lithium extraction solution of aluminum electrolysis waste |
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