CN118221140A - Method for extracting lithium carbonate from lithium-containing solution - Google Patents
Method for extracting lithium carbonate from lithium-containing solution Download PDFInfo
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- CN118221140A CN118221140A CN202311150665.6A CN202311150665A CN118221140A CN 118221140 A CN118221140 A CN 118221140A CN 202311150665 A CN202311150665 A CN 202311150665A CN 118221140 A CN118221140 A CN 118221140A
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- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 161
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 159
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 title claims abstract description 117
- 229910052808 lithium carbonate Inorganic materials 0.000 title claims abstract description 117
- 238000000034 method Methods 0.000 title claims abstract description 63
- 238000001556 precipitation Methods 0.000 claims abstract description 121
- 239000000243 solution Substances 0.000 claims abstract description 119
- 239000007788 liquid Substances 0.000 claims abstract description 70
- 229910052700 potassium Inorganic materials 0.000 claims abstract description 53
- 239000011591 potassium Substances 0.000 claims abstract description 49
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims abstract description 47
- 238000000926 separation method Methods 0.000 claims abstract description 29
- 238000007710 freezing Methods 0.000 claims abstract description 27
- 230000008014 freezing Effects 0.000 claims abstract description 27
- 239000012452 mother liquor Substances 0.000 claims abstract description 27
- 238000001816 cooling Methods 0.000 claims abstract description 25
- 239000012535 impurity Substances 0.000 claims abstract description 25
- 239000012530 fluid Substances 0.000 claims abstract description 18
- 238000010438 heat treatment Methods 0.000 claims abstract description 16
- 239000010413 mother solution Substances 0.000 claims abstract description 11
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 74
- 238000000746 purification Methods 0.000 claims description 43
- 238000001704 evaporation Methods 0.000 claims description 41
- 230000008020 evaporation Effects 0.000 claims description 37
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 37
- 239000007864 aqueous solution Substances 0.000 claims description 25
- 239000011575 calcium Substances 0.000 claims description 24
- 239000011777 magnesium Substances 0.000 claims description 24
- 150000003839 salts Chemical class 0.000 claims description 17
- HEMHJVSKTPXQMS-UHFFFAOYSA-M sodium hydroxide Inorganic materials [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 16
- 239000007791 liquid phase Substances 0.000 claims description 14
- 239000003456 ion exchange resin Substances 0.000 claims description 12
- 229920003303 ion-exchange polymer Polymers 0.000 claims description 12
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 claims description 10
- 238000005406 washing Methods 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 6
- 239000003513 alkali Substances 0.000 claims description 6
- 229910001416 lithium ion Inorganic materials 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 239000011148 porous material Substances 0.000 claims description 4
- 229910001415 sodium ion Inorganic materials 0.000 claims description 4
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 3
- 239000000292 calcium oxide Substances 0.000 claims description 3
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 229910001414 potassium ion Inorganic materials 0.000 claims description 3
- 239000000395 magnesium oxide Substances 0.000 claims description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 2
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical group [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 2
- 238000010926 purge Methods 0.000 claims 1
- 239000011734 sodium Substances 0.000 abstract description 11
- 229910052708 sodium Inorganic materials 0.000 abstract description 9
- 230000001376 precipitating effect Effects 0.000 abstract description 3
- 238000011084 recovery Methods 0.000 abstract description 3
- 239000000047 product Substances 0.000 description 72
- 238000001914 filtration Methods 0.000 description 25
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 20
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 description 16
- 230000001276 controlling effect Effects 0.000 description 15
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 15
- 229910052939 potassium sulfate Inorganic materials 0.000 description 15
- 235000011151 potassium sulphates Nutrition 0.000 description 15
- 238000005086 pumping Methods 0.000 description 14
- 229910052938 sodium sulfate Inorganic materials 0.000 description 14
- 235000011152 sodium sulphate Nutrition 0.000 description 14
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 11
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 11
- 229910052791 calcium Inorganic materials 0.000 description 11
- 229910052749 magnesium Inorganic materials 0.000 description 11
- 238000002425 crystallisation Methods 0.000 description 10
- 230000008025 crystallization Effects 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 8
- 229910052629 lepidolite Inorganic materials 0.000 description 8
- 229910018068 Li 2 O Inorganic materials 0.000 description 7
- 229910052782 aluminium Inorganic materials 0.000 description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 7
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 6
- 239000013078 crystal Substances 0.000 description 6
- 239000011737 fluorine Substances 0.000 description 6
- 229910052731 fluorine Inorganic materials 0.000 description 6
- 238000002386 leaching Methods 0.000 description 6
- 239000002893 slag Substances 0.000 description 6
- 239000012265 solid product Substances 0.000 description 6
- 239000010703 silicon Substances 0.000 description 5
- 229910052710 silicon Inorganic materials 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 description 4
- 239000010446 mirabilite Substances 0.000 description 4
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 3
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 239000000706 filtrate Substances 0.000 description 2
- INHCSSUBVCNVSK-UHFFFAOYSA-L lithium sulfate Inorganic materials [Li+].[Li+].[O-]S([O-])(=O)=O INHCSSUBVCNVSK-UHFFFAOYSA-L 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 235000021110 pickles Nutrition 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- RBTVSNLYYIMMKS-UHFFFAOYSA-N tert-butyl 3-aminoazetidine-1-carboxylate;hydrochloride Chemical compound Cl.CC(C)(C)OC(=O)N1CC(N)C1 RBTVSNLYYIMMKS-UHFFFAOYSA-N 0.000 description 2
- NPYPAHLBTDXSSS-UHFFFAOYSA-N Potassium ion Chemical compound [K+] NPYPAHLBTDXSSS-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- HEHRHMRHPUNLIR-UHFFFAOYSA-N aluminum;hydroxy-[hydroxy(oxo)silyl]oxy-oxosilane;lithium Chemical compound [Li].[Al].O[Si](=O)O[Si](O)=O.O[Si](=O)O[Si](O)=O HEHRHMRHPUNLIR-UHFFFAOYSA-N 0.000 description 1
- CNLWCVNCHLKFHK-UHFFFAOYSA-N aluminum;lithium;dioxido(oxo)silane Chemical compound [Li+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O CNLWCVNCHLKFHK-UHFFFAOYSA-N 0.000 description 1
- 229910001570 bauxite Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 238000009614 chemical analysis method Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- PQVSTLUFSYVLTO-UHFFFAOYSA-N ethyl n-ethoxycarbonylcarbamate Chemical compound CCOC(=O)NC(=O)OCC PQVSTLUFSYVLTO-UHFFFAOYSA-N 0.000 description 1
- 238000010902 jet-milling Methods 0.000 description 1
- GLXDVVHUTZTUQK-UHFFFAOYSA-M lithium hydroxide monohydrate Substances [Li+].O.[OH-] GLXDVVHUTZTUQK-UHFFFAOYSA-M 0.000 description 1
- 229940040692 lithium hydroxide monohydrate Drugs 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 229910052670 petalite Inorganic materials 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- BITYAPCSNKJESK-UHFFFAOYSA-N potassiosodium Chemical compound [Na].[K] BITYAPCSNKJESK-UHFFFAOYSA-N 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- 229910052642 spodumene Inorganic materials 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Landscapes
- Manufacture And Refinement Of Metals (AREA)
Abstract
The invention relates to the field of lithium recovery, and discloses a method for extracting lithium carbonate from a lithium-containing solution, which comprises the following steps: s1, carrying out primary concentration and cooling potassium precipitation on a lithium-containing solution; s2, heating the potassium precipitation solution obtained in the step S1 and precipitating lithium once, and carrying out solid-liquid separation to obtain a lithium carbonate product 1 and a lithium precipitation mother solution 1; s3, carrying out secondary concentration on the lithium precipitation mother liquor 1; s4, freezing the concentrated solution obtained in the step S3; s5, removing impurities from the refrigerating fluid obtained in the step S4; s6, carrying out secondary lithium precipitation on the purifying liquid obtained in the step S5, and carrying out solid-liquid separation to obtain a lithium carbonate product 2 and a lithium precipitation mother liquor 2; wherein, the lithium precipitation mother liquor 2 returns to S1. The method can realize the efficient separation of low-lithium, high-potassium and high-sodium solutions, and simultaneously obtain high-quality lithium carbonate products.
Description
Technical Field
The invention relates to the field of lithium recovery, in particular to a method for extracting lithium carbonate from a lithium-containing solution.
Background
Lithium is an important energy metal called "white petroleum" and has very wide application, and is becoming a new motive force for world energy development. At present, the present China has basically established the modern basic lithium industry which is based on ore lithium extraction and brine lithium extraction and covers series products such as lithium carbonate, lithium chloride, lithium hydroxide, metal lithium and the like. The existing industrial raw materials for extracting lithium from ores are generally spodumene (Li 2 O > 5.0%), petalite (Li 2 O > 5.0%), lepidolite (Li 2 O > 2.5%), lithium-ion-containing bauxite (Li 2 O > 5.5%), and the like, wherein the Li 2 O content is higher, the impurity ions in the solution are less, and the existing industry has a mature recovery process. However, since 2019, the price of lithium salt is continuously high, and under the background that high-quality lithium ore resources are monopolized by several high-quality lithium ore enterprises at home and abroad, research on a process for extracting lithium from low-grade lepidolite (Li 2 O < 1.5%) and low-grade lithium-containing waste residues is getting more and more attention, and the low-grade lithium resources usually contain a large amount of Na, K, rb, cs, al, si, ca and other impurity elements. Taking low-grade lepidolite (Li 2 O is less than 1.5%) as a raw material, the common potassium content of lepidolite is between 6 and 10 percent, the single Li content of a lithium extraction solution is between 2g/L and 5g/L, the K content is between 25g/L and 50g/L, the Na content is between 20g/L and 50g/L, and the potassium content and the sodium content of the solution are nearly ten times as high as the lithium content.
CN112142081B discloses a method for preparing battery grade lithium carbonate by using lepidolite, which specifically comprises the following steps: roasting and leaching lepidolite, adding a defluorinating agent to remove fluorine, concentrating, removing calcium and magnesium by using a chelating ion exchange resin to obtain a refined lithium solution, adding the refined lithium solution into a refined sodium carbonate solution of which the calcium and magnesium are removed by using the chelating ion exchange resin, reacting, and settling to obtain coarse lithium carbonate and a lithium precipitation mother solution; concentrating and evaporating the lithium precipitation mother solution, adding the frozen salt into the refined lithium solution for recycling, washing the crude lithium carbonate, settling, centrifugally separating, drying, carrying out jet milling, mixing and packaging to obtain the battery-grade lithium carbonate. However, the leaching solution is concentrated and then directly subjected to lithium precipitation, potassium salt is not separated out in the first-step concentration process, so that the existence of potassium sulfate and sodium sulfate fine crystals can generate peritectic phenomenon in the lithium precipitation process, and a carbonization system is needed for improving the quality of lithium carbonate, so that the cost is high; meanwhile, the lithium precipitation mother liquor returns to be recycled after freezing and crystallizing, which results in lower direct yield of lithium carbonate and poor economic benefit.
CN102010991B discloses a sulfuric acid method for extracting lithium from lepidolite to obtain pickle liquor, then adding aluminum sulfate or aluminum hydroxide into the pickle liquor to reach an Al 3+ supersaturated state, and finally freezing to remove potassium, wherein the strong acid medium has very high requirements on equipment, and the aluminum is required to reach the supersaturated state and is very complicated to return to remove aluminum.
CN112142080B discloses a method for preparing battery grade lithium carbonate by freezing and recycling concentrated mother solution of precipitated lithium, which comprises the following steps: (1) Roasting and leaching lepidolite to obtain a leaching solution, purifying, concentrating and evaporating the leaching solution, precipitating lithium, and filtering to obtain lithium carbonate and lithium precipitation mother liquor; (2) Concentrating and evaporating the lithium precipitation mother liquor to obtain lithium precipitation concentrated mother liquor; (3) Adding the lithium precipitation mother liquor in the step (2) into the leaching solution to obtain mixed liquor, purifying, concentrating, evaporating, freezing to remove potassium and sodium salts, filtering, introducing ion exchange resin to remove calcium and magnesium, and settling to obtain battery-grade lithium carbonate and lithium precipitation mother liquor, wherein the lithium precipitation mother liquor is treated and recycled in the process.
Therefore, for a solution with low lithium, high potassium and high sodium, it is important to develop a method which is technically feasible and can be industrialized to extract lithium from the solution with low lithium.
Disclosure of Invention
The invention aims to solve the problems of complicated process, low direct yield and poor economic benefit of the prior art for extracting lithium from a low-lithium-content solution, and provides a method for extracting lithium carbonate from a lithium-content solution, which can effectively separate the lithium-content solution and obtain a high-quality lithium carbonate product.
In order to achieve the above object, the present invention provides a method for extracting lithium carbonate from a lithium-containing solution, wherein the method comprises the steps of:
s1, carrying out primary concentration and cooling on a lithium-containing solution to separate potassium, and carrying out primary solid-liquid separation to obtain potassium separating liquid and mixed salt 1;
s2, heating the potassium precipitation solution and carrying out primary lithium precipitation, and carrying out secondary solid-liquid separation to obtain a lithium carbonate product 1 and a lithium precipitation mother solution 1;
S3, carrying out secondary concentration on the lithium precipitation mother liquor 1, and carrying out solid-liquid separation for three times to obtain concentrated solution and mixed salt 2;
s4, freezing the concentrated solution, and performing solid-liquid separation for four times to obtain glaserite and frozen solution;
S5, removing impurities from the refrigerating fluid to obtain a purified fluid;
S6, carrying out secondary lithium precipitation on the purifying liquid, and carrying out solid-liquid separation for five times to obtain a lithium carbonate product 2 and a lithium precipitation mother liquid 2; wherein, the lithium precipitation mother liquor 2 returns to S1.
Through the technical scheme, the invention has the beneficial effects that:
The method for extracting lithium carbonate from the lithium-containing solution provided by the invention comprises the working procedures of primary concentration, cooling and potassium precipitation, reverse heating, primary lithium precipitation, secondary concentration, freezing and mirabilite precipitation, purification and impurity removal, secondary lithium precipitation and the like, and realizes the efficient separation of low-lithium, high-potassium and high-sodium solutions.
The invention adopts the processes of primary concentration, cooling and potassium precipitation, reverse heating and primary lithium precipitation, and the first aspect realizes the improvement of the concentration of lithium sulfate in the lithium-containing solution; in the second aspect, a part of potassium sulfate with higher purity is separated out; in the third aspect, in the primary lithium precipitation precursor solution, the mixed salt 1 (potassium sulfate and sodium sulfate) is in an unsaturated state, so that the phenomenon of lithium carbonate peritectic in the lithium precipitation process caused by crystallization of potassium sulfate and sodium sulfate is avoided, the quality of a lithium carbonate product is further improved, and the percentage content of Li 2CO3 is more than or equal to 99.5wt% after secondary stirring and washing of the lithium carbonate product obtained by primary lithium precipitation.
The invention adopts the processes of freezing and separating mirabilite, purifying and removing impurities and secondary lithium precipitation, realizes the deep removal of potassium sodium salt and impurity ions, and the lithium carbonate product obtained by secondary lithium precipitation directly reaches battery grade lithium carbonate after secondary stirring and washing.
Drawings
Fig. 1 is a flow chart of a method for extracting lithium carbonate from a lithium-containing solution in one embodiment of the invention.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The invention provides a method for extracting lithium carbonate from a lithium-containing solution, wherein the method comprises the following steps:
s1, carrying out primary concentration and cooling on a lithium-containing solution to separate potassium, and carrying out primary solid-liquid separation to obtain potassium separating liquid and mixed salt 1;
s2, heating the potassium precipitation solution and carrying out primary lithium precipitation, and carrying out secondary solid-liquid separation to obtain a lithium carbonate product 1 and a lithium precipitation mother solution 1;
S3, carrying out secondary concentration on the lithium precipitation mother liquor 1, and carrying out solid-liquid separation for three times to obtain concentrated solution and mixed salt 2;
s4, freezing the concentrated solution, and performing solid-liquid separation for four times to obtain glaserite and frozen solution;
S5, removing impurities from the refrigerating fluid to obtain a purified fluid;
S6, carrying out secondary lithium precipitation on the purifying liquid, and carrying out solid-liquid separation for five times to obtain a lithium carbonate product 2 and a lithium precipitation mother liquid 2; wherein, the lithium precipitation mother liquor 2 returns to S1.
The lithium-containing solution is subjected to primary concentration, cooling and potassium precipitation, and primary solid-liquid separation to obtain mixed salt 1 (potassium sulfate salt and sodium sulfate salt) and potassium precipitation solution respectively. The concentration of lithium sulfate in the lithium-containing solution is improved by primary concentration; a part of potassium sulfate with higher purity can be separated out through cooling and potassium separation, and a small amount of sodium sulfate can be separated out; and after the potassium solution is heated, carrying out primary lithium precipitation, so that part of potassium sulfate and sodium sulfate fine crystals precipitated by the potassium solution are redissolved, and the potassium sulfate and the sodium sulfate in the potassium solution are in an unsaturated state, thereby avoiding the phenomenon of lithium carbonate peritectic phenomenon in the primary lithium precipitation process caused by the crystallization of the potassium sulfate and the sodium sulfate, and further improving the quality of a lithium carbonate product 1 obtained by primary lithium precipitation. The concentration of lithium ions can be further improved by carrying out secondary concentration on the lithium precipitation mother liquor 1, sodium sulfate can be precipitated, and after carrying out secondary concentration on the lithium precipitation mother liquor 1, mixed salt 2 of potassium sulfate and sodium sulfate (the concentration of the potassium sulfate is more in the primary concentration and more in the secondary concentration and precipitation) and concentrated solution are obtained through solid-liquid separation. Freezing and crystallizing the concentrated solution to separate out glaserite (K 3Na(SO4)2·10H2 O), and carrying out solid-liquid separation to obtain the glaserite and the frozen solution respectively. Removing impurities from the refrigerating fluid, and removing impurities including fluorine, silicon, calcium, magnesium, aluminum and the like to obtain a purifying fluid. Only a part of lithium in the primary lithium precipitation can be precipitated, because the concentration of lithium in the potassium precipitation solution gradually decreases along with the progress of lithium precipitation, and at the moment, more lithium precipitating agent is added to precipitate lithium, and the lithium is not converted any more, so that secondary lithium precipitation is performed after impurity removal.
According to the present invention, preferably, in S1, the primary concentration process includes: the lithium-containing solution was treated with (1-6): the evaporation ratio of 1 is preferably (2-5): 1. the evaporation ratio refers to the ratio of the flow rates of the lithium-containing solution and the concentrated solution obtained by the primary concentration when the evaporation concentration is performed. The concentration is carried out for one time at the evaporation ratio, so that the lithium ion concentration of the lithium-containing solution can be improved, otherwise, the direct yield of lithium carbonate in the primary lithium precipitation process is low.
According to a preferred embodiment of the present invention, both the primary and secondary concentrates are evaporated using a mechanical vapor recompression evaporation system (MVR system); the evaporation ratio is the ratio of the inlet flow to the outlet flow of the MVR system.
According to the invention, preferably, the process of cooling and potassium precipitation comprises the following steps: the liquid phase product obtained by evaporation is cooled to 0-60 ℃, preferably 30-60 ℃. The temperature of the potassium precipitation after cooling is too low, so that the subsequent temperature rising energy consumption is larger; the temperature is too high, so that the potassium salt precipitation efficiency is low, and the subsequent temperature rising comprehensive energy consumption is low while the potassium salt precipitation is ensured to be mostly carried out at the temperature.
According to the present invention, it is preferable that the lithium ion content in the lithium-containing solution is 5g/L or less, the potassium ion content is 25g/L or more, and the sodium ion content is 25g/L or more. Aiming at the lithium-containing solution with the contents of lithium ions, potassium ions and sodium ions meeting the conditions, the method for extracting the lithium carbonate provided by the invention can obtain a lithium carbonate product with high quality.
According to the present invention, preferably, the heating process includes: the potassium precipitation solution is heated to 65-95 ℃, preferably 75-95 ℃. The potassium sulfate and sodium sulfate fine-crystal salts which are precipitated can not be redissolved due to the excessively low temperature of the potassium precipitation solution, and the potassium precipitation solution is heated to the temperature, so that the potassium sulfate and sodium sulfate fine-crystal salts which are precipitated can be redissolved.
According to the present invention, preferably, in S2, the primary lithium precipitation process includes: the potassium precipitation solution and the sodium carbonate aqueous solution 1 are mixed for reaction.
According to the present invention, preferably, the sodium carbonate content in the sodium carbonate aqueous solution 1 is 15 to 32wt%, and the temperature of the sodium carbonate aqueous solution 1 is 80 to 90 ℃. When the content of sodium carbonate in the sodium carbonate aqueous solution 1 meets the range, the direct yield of lithium can be improved, and the content of impurities wrapped by the lithium carbonate is low; when the temperature of the sodium carbonate aqueous solution 1 satisfies this range, the progress of the lithium precipitation reaction can be promoted.
According to the present invention, the aqueous sodium carbonate solution 1 is preferably used in an amount of 30 to 50g based on 100g of the weight of the potassium separating solution.
According to the present invention, preferably, in S3, the secondary concentration process includes: the lithium precipitation mother liquor 1 is prepared by the following steps of (1-6): the evaporation ratio of 1 is preferably (2-5): 1. the concentration of lithium can be improved by carrying out primary concentration at the evaporation ratio, so that lithium carbonate products with higher quality can be separated out from secondary lithium precipitation, and sodium sulfate salts can be separated out.
According to the invention, preferably, in S4, the temperature of the freezing is between-5 ℃ and 15 ℃, preferably between-5 ℃ and 10 ℃. The freezing temperature is too high, so that the efficiency of separating out the glauber salt is low, the quality of lithium carbonate obtained by secondary lithium precipitation is further affected, and the freezing temperature is too low, so that mother liquor is frozen.
According to the present invention, preferably, in S5, the impurity removal process includes:
primary purifying the mixed alkaline oxide of the refrigerating fluid;
Performing secondary purification on the liquid-phase product mixed alkali liquor obtained by the primary purification;
And (3) contacting the liquid phase product obtained by the secondary purification with ion exchange resin to perform tertiary purification to obtain the purified liquid.
Primary purifying the refrigerating fluid by using alkaline oxide to remove fluorine and silicon in the refrigerating fluid; regulating pH of the liquid phase product obtained by the primary purification by alkali liquor, and carrying out secondary purification to remove impurities such as calcium, magnesium, aluminum and the like in the refrigerating fluid; and the liquid phase product obtained by the second-stage purification is contacted with ion exchange resin to carry out third-stage purification so as to further remove impurities such as calcium, magnesium and the like in the refrigerating fluid.
According to the present invention, preferably, the conditions of the primary purification include: the pH value is 7-14, preferably 9-12; the time is 0.5-3h, preferably 0.5-1.5h; the temperature is 25-95deg.C, preferably 55-85deg.C; wherein the pH value is the pH value of a mixed system of the refrigerating fluid and the alkaline oxide.
According to the present invention, preferably, the conditions of the secondary purification include: the pH value is 7-14, preferably 9-12; the time is 0.5-3h, preferably 0.5-2h; the temperature is 25-95 ℃, preferably 55-85 ℃, wherein the pH value is the pH value of a mixed system of liquid phase products obtained by primary purification and alkali liquor.
According to the present invention, preferably, the concentrations of Ca 2+ and Mg 2+ in the purification liquid are each independently 1Mg/L or less.
According to the invention, preferably, the basic oxide is selected from magnesium oxide and/or calcium oxide.
According to the invention, preferably, the lye is selected from sodium hydroxide and/or sodium carbonate.
According to the present invention, preferably, the ion exchange resin is selected from chelating ion exchange resins having an average pore size of 0.3 to 0.8 mm.
According to the present invention, preferably, in S6, the secondary lithium precipitation process includes: the purified solution and the sodium carbonate aqueous solution 2 are mixed to react.
According to the present invention, the aqueous sodium carbonate solution 2 is preferably used in an amount of 60 to 80g based on 100g of the weight of the purification liquid.
According to the present invention, preferably, the sodium carbonate content in the sodium carbonate aqueous solution 2 is 15 to 32wt%, and the temperature of the sodium carbonate aqueous solution 2 is 80 to 90 ℃.
According to the present invention, preferably, the method further comprises: the lithium carbonate product 1 is subjected to at least 1 wash with water, preferably more than 2, more preferably 2.
According to the present invention, preferably, the weight ratio of the lithium carbonate product 1 to water is 1: (2-10), preferably 1: (4-8).
According to the present invention, preferably, the method further comprises: the lithium carbonate product 2 is subjected to at least 1 wash with water, preferably more than 2, more preferably 2.
According to the present invention, preferably, the weight ratio of the lithium carbonate product 2 to water is 1: (2-10), preferably 1: (4-8).
According to the present invention, it is preferable that the content of lithium carbonate in the lithium carbonate product 1 is 99.5wt% or more.
According to the present invention, preferably, the lithium carbonate product 2 is battery grade lithium carbonate.
In the present invention, the primary solid-liquid separation, the secondary solid-liquid separation, the tertiary solid-liquid separation, the quaternary solid-liquid separation and the quintet solid-liquid separation may be performed by conventional methods in the art, for example, may be performed by filtration.
According to one embodiment of the present invention, as shown in fig. 1, the method for extracting lithium carbonate from a lithium-containing solution comprises the steps of:
S1, pumping the lithium-containing solution into an MVR system for evaporation (primary concentration), and controlling the evaporation ratio (inlet flow/outlet flow) to be (1-6): 1, a step of; cooling the concentrated liquid phase product to 0-60 ℃, cooling and separating potassium salt, and filtering to obtain potassium separating liquid;
S2, pumping the potassium precipitation pump into a heating tank and heating to 65-95 ℃; adding the heated potassium precipitation solution into sodium carbonate aqueous solution 1 with the concentration of 15-32wt% and the temperature of 80-90 ℃ for primary lithium precipitation (the dosage of the sodium carbonate aqueous solution 1 is 30-50g based on the weight of the potassium precipitation solution being 100 g), and filtering to obtain a solid product and lithium precipitation mother solution 1; the liquid-solid ratio of the added solution is (2-10): 1, carrying out countercurrent washing on the solid product for 2 times to obtain a lithium carbonate product 1;
S3, pumping the lithium precipitation mother liquor 1 into an MVR system for evaporation and salt precipitation (secondary concentration), and controlling the evaporation ratio (inlet flow/outlet flow) to be (1-6): 1, filtering to obtain concentrated solution;
S4, pumping the concentrated solution into a freezing crystallization system, controlling the freezing temperature to be between-5 ℃ and 15 ℃, and filtering to obtain glaserite and frozen liquid;
S5, performing primary purification on the mixed alkaline oxide of the refrigerating fluid to remove fluorine and silicon, controlling the pH value of the mixed system to be 7-14, the purification time to be 0.5-3h, the purification temperature to be 25-95 ℃, and filtering to obtain a purified fluid 1 and purified slag 1; regulating pH of the purified liquid 1 with alkali liquor to perform secondary purification so as to remove impurities such as calcium, magnesium, aluminum and the like, controlling the pH value of the system to be 7-14, purifying for 0.5-3h at 25-95 ℃, and filtering to obtain purified liquid 2 and purified slag 2; contacting the purified liquid 2 with chelating ion exchange resin with the average pore diameter of 0.3-0.8mm for three-stage purification, and deeply removing impurities such as calcium, magnesium and the like to obtain purified liquid 3; the concentration of Ca 2+ and Mg 2+ in the purifying liquid 3 is less than or equal to 1Mg/L;
S6, pumping the purified solution 3 into a heating tank, adding the heated purified solution into a sodium carbonate aqueous solution 2 with the concentration of 15-32wt% and the temperature of 80-90 ℃ for secondary lithium precipitation (the dosage of the sodium carbonate aqueous solution 2 is 60-80g based on 100g of the weight of the purified solution 3), and filtering to obtain a lithium carbonate product 2 and a lithium precipitation mother solution 2; adding water with the liquid-solid ratio of (2-10) 1 to carry out countercurrent washing on the lithium carbonate product 2 for 2 times; the lithium precipitation mother liquor 2 returns to S1.
The present invention will be described in detail below by way of examples and comparative examples. In the following examples, unless otherwise specified, the methods are conventional; the reagents and materials used, unless otherwise indicated, are all those commercially available.
The purity of Li 2CO3, the mass percentages of Na, K and SO 4 2- are determined according to GB/T11064-2013 lithium carbonate, lithium hydroxide monohydrate and lithium chloride chemical analysis method.
The chemical compositions of the lithium-containing solutions of the respective examples and comparative examples are shown in table 1.
TABLE 1
| Chemical composition | Li | K | Na | SO4 2- | F |
| Concentration (g/L) | 4.5 | 34 | 25 | 130 | 0.1 |
The following examples are presented to illustrate the method of extracting lithium carbonate from a lithium-containing solution.
Example 1
S1, pumping the lithium-containing solution into an MVR system for evaporation (primary concentration), and controlling the evaporation ratio (inlet flow/outlet flow) to be 3:1, a step of; cooling the concentrated liquid phase product to 60 ℃, cooling and separating potassium salt, and filtering to obtain potassium separating liquid;
S2, pumping the potassium precipitation pump into a heating tank and heating to 90 ℃; adding the heated potassium precipitation solution into a sodium carbonate aqueous solution 1 with the concentration of 20wt% and the temperature of 90 ℃ for primary lithium precipitation (the dosage of the sodium carbonate aqueous solution 1 is 50g based on the weight of the potassium precipitation solution being 100 g), and filtering to obtain a solid product and a lithium precipitation mother solution 1; the liquid-solid ratio of the added solution is 5:1, carrying out countercurrent washing on the solid product for 2 times to obtain a lithium carbonate product 1;
s3, pumping the lithium precipitation mother liquor 1 into an MVR system for evaporation and salt precipitation (secondary concentration), and controlling the evaporation ratio (inlet flow/outlet flow) to be 3.5:1, filtering to obtain concentrated solution;
s4, pumping the concentrated solution into a freezing crystallization system, controlling the freezing temperature at 10 ℃, and filtering to obtain glaserite and a freezing solution;
S5, performing primary purification on the frozen liquid mixed calcium oxide to remove fluorine and silicon, controlling the pH value of the mixed system to be 10, the purification time to be 1h, the purification temperature to be 85 ℃, and filtering to obtain a purified liquid 1 and purified slag 1; the method comprises the steps of (1) adjusting the pH value of a mixed solution of sodium hydroxide and sodium carbonate (the content of sodium hydroxide in the mixed solution is 20wt%, and the content of sodium carbonate is 32 wt%) to carry out secondary purification so as to remove impurities such as calcium, magnesium, aluminum and the like, controlling the pH value of a system to be 12, purifying for 1h, and obtaining a purified solution 2 and a purified slag 2 through filtering at the purification temperature of 85 ℃; the purifying liquid 2 is contacted with chelating ion exchange resin with the average pore diameter of 0.3mm for three-stage purification, and impurities such as calcium, magnesium and the like are deeply removed to obtain purifying liquid 3; the concentrations of Ca 2+ and Mg 2+ in the purified liquid 3 are 0.5Mg/L and 0.2Mg/L, respectively;
S6, pumping the purifying liquid 3 into a heating tank, controlling the temperature of the purifying liquid 3 at 90 ℃, adding the purifying liquid into a sodium carbonate aqueous solution 2 with the concentration of 32wt% and the temperature of 90 ℃ for secondary lithium precipitation (the dosage of the sodium carbonate aqueous solution 2 is 70g based on 100g of the weight of the purifying liquid 3), and filtering to obtain a lithium carbonate product 2 and a lithium precipitation mother solution 2; the liquid-solid ratio of the added solution is 5:1, carrying out 2 times of countercurrent washing on the lithium carbonate product 2 by water; the lithium precipitation mother liquor 2 returns to S1.
Example 2
S1, pumping the lithium-containing solution into an MVR system for evaporation (primary concentration), and controlling the evaporation ratio (inlet flow/outlet flow) to be 4:1, a step of; cooling the concentrated liquid phase product to 35 ℃, cooling and separating potassium salt, and filtering to obtain potassium separating liquid;
S2-S6 are as in example 1; wherein, the concentration of Ca 2+ and Mg 2+ in the purified liquid 3 obtained in the step S5 is 0.5Mg/L and 0.2Mg/L respectively.
A lithium carbonate product 1 and a lithium carbonate product 2 are obtained.
Example 3
S1, pumping the lithium-containing solution into an MVR system for evaporation (primary concentration), and controlling the evaporation ratio (inlet flow/outlet flow) to be 3.5:1, a step of; cooling the concentrated liquid phase product to 40 ℃, cooling and separating potassium salt, and filtering to obtain potassium separating liquid;
S2 is as in example 1; obtaining a lithium carbonate product 1;
S3, pumping the lithium precipitation mother liquor 1 into an MVR system for evaporation and salt precipitation (secondary concentration), and controlling the evaporation ratio (inlet flow/outlet flow) to be 4:1, filtering to obtain concentrated solution;
s4, pumping the concentrated solution into a freezing crystallization system, controlling the freezing temperature at 0 ℃, and filtering to obtain glaserite and a freezing solution;
s5 As in example 1, the concentrations of Ca 2+ and Mg 2+ in the purified liquid 3 obtained were 0.5Mg/L and 0.2Mg/L, respectively;
s6 is the same as in example 1; lithium carbonate product 2 is obtained.
Example 4
Lithium carbonate was extracted from the lithium-containing solution according to the method of example 1, except that the evaporation ratio of the primary concentration was different. Specifically, in S1, the evaporation ratio (inlet flow rate/outlet flow rate) is controlled to be 6:1. the concentration of Ca 2+ and Mg 2+ in the obtained purified liquid 3 is 0.5Mg/L and 0.2Mg/L respectively; a lithium carbonate product 1 and thus a lithium carbonate product 2 is obtained.
Example 5
Lithium carbonate was extracted from a lithium-containing solution in the same manner as in example 1, except that the temperature at which the potassium salt was separated by cooling was different. Specifically, in S1, the concentrated liquid phase product is cooled to 65 ℃ and potassium salt is separated out by cooling. The concentration of Ca 2+ and Mg 2+ in the obtained purified liquid 3 is 0.5Mg/L and 0.3Mg/L respectively; a lithium carbonate product 1 and thus a lithium carbonate product 2 is obtained.
Example 6
Lithium carbonate was extracted from the lithium-containing solution as in example 1, except that in S2, potassium precipitation was pumped into the heating tank and warmed to 70 ℃. The concentration of Ca 2+ and Mg 2+ in the obtained purified liquid 3 is 0.5Mg/L and 0.2Mg/L respectively; a lithium carbonate product 1 and thus a lithium carbonate product 2 is obtained.
Example 7
Lithium carbonate was extracted from the lithium-containing solution according to the method of example 1, except that the evaporation ratio of the secondary concentration was different. Specifically, in S3, the evaporation ratio (inlet flow rate/outlet flow rate) is controlled to be 6:1. the concentration of Ca 2+ and Mg 2+ in the obtained purified liquid 3 is 0.5Mg/L and 0.1Mg/L respectively; a lithium carbonate product 1 and thus a lithium carbonate product 2 is obtained.
Example 8
Lithium carbonate was extracted from the lithium-containing solution in the same manner as in example 1, except that in S4, the temperature of the freeze crystallization was controlled at 15 ℃. The concentration of Ca 2+ and Mg 2+ in the obtained purified liquid 3 is 0.5Mg/L and 0.2Mg/L respectively; a lithium carbonate product 1 and thus a lithium carbonate product 2 is obtained.
Example 9
Lithium carbonate was extracted from the lithium-containing solution according to the method of example 1, except that the conditions for the primary purification were different. Specifically, in S5, the freezing solution and the alkaline oxide are mixed for primary purification to remove fluorine and silicon, the pH value of the mixed system is controlled to be 8, the purification temperature is 85 ℃, and the purification solution 1 and the purification slag 1 are obtained through filtration. The concentration of Ca 2+ and Mg 2+ in the obtained purified liquid 3 is 0.5Mg/L and 0.2Mg/L respectively; a lithium carbonate product 1 and thus a lithium carbonate product 2 is obtained.
Example 10
Lithium carbonate was extracted from the lithium-containing solution according to the method of example 1, except that the conditions for the secondary purification were different. Specifically, in S5, the pH value of the purifying liquid 1 is adjusted by alkali liquor for secondary purification so as to remove impurities such as calcium, magnesium, aluminum and the like, the pH value of the system is controlled to be 7, the purifying temperature is 80 ℃, and the purifying liquid 2 and the purifying slag 2 are obtained through filtering. The concentration of Ca 2+ and Mg 2+ in the obtained purified liquid 3 is 0.5Mg/L and 0.2Mg/L respectively; a lithium carbonate product 1 and thus a lithium carbonate product 2 is obtained.
Comparative example 1
Lithium carbonate was extracted from the lithium-containing solution in the same manner as in example 1, except that the potassium salt was not separated out by cooling in S1 and the temperature rise was not performed in S2. Specifically, in S1, a lithium-containing solution is pumped into the MVR system for evaporation, and the evaporation ratio is controlled to be 3:1, filtering the evaporated slurry; s2, adding the filtrate obtained in the step S1 into a sodium carbonate aqueous solution 1 with the concentration of 20wt% and the temperature of 90 ℃ for primary lithium precipitation (the dosage of the sodium carbonate aqueous solution 1 is 50g based on the weight of the filtrate of 100 g), and filtering to obtain a solid product and a lithium precipitation mother liquor 1; the liquid-solid ratio of the added solution is 5:1, carrying out countercurrent washing on the solid product for 2 times to obtain a lithium carbonate product 1. And further a lithium carbonate product 2 was obtained.
Comparative example 2
Lithium carbonate was extracted from the lithium-containing solution according to the method of example 1, except that the freezing crystallization of S4 and the impurity removal step of S5 were not performed, and in S6, the concentrated solution obtained in S3 was directly added to the sodium carbonate aqueous solution 2 to perform secondary lithium precipitation. A lithium carbonate product 1 and thus a lithium carbonate product 2 is obtained.
The purity of Li 2CO3 and the mass percentages of Na ion, K ion and SO 4 2- in the lithium carbonate product 1 and the lithium carbonate product 2 obtained in each of examples and comparative examples were measured, and the results are shown in table 2.
TABLE 2
As can be seen from the results of Table 2, by adopting the method for extracting lithium carbonate from lithium-containing solution provided by the invention, the purity of the lithium carbonate product 1 obtained by primary lithium precipitation in examples 1-10 is more than 99.5wt% and reaches the industrial level standard; the purity of the lithium carbonate product 2 obtained by secondary lithium precipitation is more than 99.5 weight percent and reaches the battery grade standard. The comparative example 1 is not subjected to cooling potassium salt precipitation and heating, lithium is directly precipitated once after evaporation, and the purity of the lithium carbonate product 1 obtained by the primary lithium precipitation is lower than 99.5 weight percent because of severe peritectic potassium sulfate and sodium sulfate, even the purity of the lithium carbonate product cannot reach the standard of industrial grade lithium carbonate; however, in comparative example 1, impurities such as potassium, sodium and the like are greatly removed by the freezing and precipitation mirabilite and the three-stage purification process, and the secondary lithium carbonate can reach the battery level standard. The comparative example 2 was not subjected to freeze crystallization and purification to remove impurities, and was directly subjected to secondary lithium precipitation, and the purity of the obtained lithium carbonate product 2 was more than 99.5wt%, but only up to industrial-grade standards.
In addition, in example 4, the evaporation ratio of primary concentration is increased, in example 5, the temperature of the potassium salt is reduced by cooling, in example 6, the temperature of the potassium salt precipitation solution is reduced, the temperature of the redissolved potassium sulfate and the sodium sulfate fine crystal salt is increased, and in lithium carbonate product 1 obtained by primary precipitation, although the lithium carbonate product 1 also meets the industrial grade standard, the content of Na, K and SO 4 2- in the lithium carbonate product 1 is increased or the purity of Li 2CO3 is reduced compared with example 1. Example 7 increased the evaporation ratio of the secondary concentration, example 8 increased the temperature of the freeze crystallization, examples 9 and 10 changed the conditions of the primary purification and the secondary purification, respectively, and lithium carbonate product 2 obtained by secondary precipitation of lithium reached the battery level standard as compared with example 1, but the Na, K and SO 4 2- contents in lithium carbonate product 2 were increased or the purity of Li 2CO3 was decreased as compared with example 1. The evaporation ratio of primary concentration is described, the temperature of potassium salt is reduced, the temperature of potassium salt precipitation solution is increased, the temperature of redissolved potassium sulfate and sodium sulfate fine crystal salt is increased, the quality of a lithium carbonate product 1 obtained by primary lithium precipitation is affected, but the quality of a lithium carbonate product 2 obtained by secondary lithium precipitation is affected little; the evaporation ratio of the secondary concentration, the freezing crystallization temperature and the purification conditions can influence the quality of the lithium carbonate product 2 obtained by secondary lithium precipitation.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (10)
1. A method of extracting lithium carbonate from a lithium-containing solution, the method comprising the steps of:
s1, carrying out primary concentration and cooling on a lithium-containing solution to separate potassium, and carrying out primary solid-liquid separation to obtain potassium separating liquid and mixed salt 1;
s2, heating the potassium precipitation solution and carrying out primary lithium precipitation, and carrying out secondary solid-liquid separation to obtain a lithium carbonate product 1 and a lithium precipitation mother solution 1;
S3, carrying out secondary concentration on the lithium precipitation mother liquor 1, and carrying out solid-liquid separation for three times to obtain concentrated solution and mixed salt 2;
s4, freezing the concentrated solution, and performing solid-liquid separation for four times to obtain glaserite and frozen solution;
S5, removing impurities from the refrigerating fluid to obtain a purified fluid;
S6, carrying out secondary lithium precipitation on the purifying liquid, and carrying out solid-liquid separation for five times to obtain a lithium carbonate product 2 and a lithium precipitation mother liquid 2; wherein, the lithium precipitation mother liquor 2 returns to S1.
2. The method of claim 1, wherein in S1, the primary concentrating comprises: the lithium-containing solution was treated with (1-6): the evaporation ratio of 1 is preferably (2-5): 1, a step of;
preferably, the process of cooling and potassium separation comprises the following steps: cooling the liquid phase product obtained by evaporation to 0-60 ℃;
preferably, in the lithium-containing solution, the content of lithium ions is not more than 5g/L, the content of potassium ions is not less than 25g/L, and the content of sodium ions is not less than 25g/L.
3. The method according to claim 1 or 2, wherein in S2, the process of increasing the temperature comprises: heating the potassium precipitation solution to 65-95 ℃, preferably 75-95 ℃;
the primary lithium precipitation process comprises the following steps: mixing the potassium precipitation solution with the sodium carbonate aqueous solution 1 for reaction;
Preferably, the sodium carbonate content in the sodium carbonate aqueous solution 1 is 15-32wt%, and the temperature of the sodium carbonate aqueous solution 1 is 80-90 ℃.
4. A method according to any one of claims 1-3, wherein in S3 the secondary concentration comprises: the lithium precipitation mother liquor 1 is prepared by the following steps of (1-6): the evaporation ratio of 1 is preferably (2-5): 1, a step of;
Preferably, in S4, the temperature of the freezing is from-5 ℃ to 15 ℃, preferably from-5 ℃ to 10 ℃.
5. The method according to any one of claims 1 to 4, wherein in S5, the process of removing impurities comprises:
primary purifying the mixed alkaline oxide of the refrigerating fluid;
Performing secondary purification on the liquid-phase product mixed alkali liquor obtained by the primary purification;
And (3) contacting the liquid phase product obtained by the secondary purification with ion exchange resin to perform tertiary purification to obtain the purified liquid.
6. The method of claim 5, wherein the conditions of the primary purge comprise: the pH value is 7-14, preferably 9-12; the time is 0.5-3h, preferably 0.5-1.5h; the temperature is 25-95deg.C, preferably 55-85deg.C;
Preferably, the conditions of the secondary purification include: the pH value is 7-14, preferably 9-12; the time is 0.5-3h, preferably 0.5-2h; the temperature is 25-95deg.C, preferably 55-85deg.C;
preferably, the concentration of Ca 2+ and Mg 2+ in the purification liquid is 1Mg/L or less each independently.
7. The method according to claim 5 or 6, characterized in that the basic oxide is selected from magnesium oxide and/or calcium oxide;
Preferably, the lye is selected from sodium hydroxide and/or sodium carbonate;
preferably, the ion exchange resin is selected from chelating ion exchange resins having an average pore size of 0.3-0.8 mm.
8. The method according to any one of claims 1 to 7, wherein in S6, the secondary lithium precipitation process comprises: mixing the purified solution with the sodium carbonate aqueous solution 2 for reaction;
Preferably, the sodium carbonate content in the sodium carbonate aqueous solution 2 is 15-32wt%, and the temperature of the sodium carbonate aqueous solution 2 is 80-90 ℃.
9. The method according to any one of claims 1-8, further comprising: washing the lithium carbonate product 1 with water at least 1 time, preferably more than 2 times;
preferably, the weight ratio of the lithium carbonate product 1 to the water is 1: (2-10), preferably 1: (4-8);
Preferably, the method further comprises: washing the lithium carbonate product 2 with water at least 1 time, preferably more than 2 times;
preferably, the weight ratio of the lithium carbonate product 2 to water is 1: (2-10), preferably 1: (4-8).
10. The method according to any one of claims 1 to 9, wherein the content of lithium carbonate in the lithium carbonate product 1 is 99.5wt% or more;
Preferably, the lithium carbonate product 2 is battery grade lithium carbonate.
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