CN111268702A - Method and device for preparing battery-grade lithium carbonate by using membrane separation technology - Google Patents
Method and device for preparing battery-grade lithium carbonate by using membrane separation technology Download PDFInfo
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- 239000012528 membrane Substances 0.000 title claims abstract description 119
- 229910052808 lithium carbonate Inorganic materials 0.000 title claims abstract description 95
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 title claims abstract description 92
- 238000000034 method Methods 0.000 title claims abstract description 55
- 238000000926 separation method Methods 0.000 title claims description 20
- 238000005516 engineering process Methods 0.000 title claims description 17
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 148
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims abstract description 113
- 238000006243 chemical reaction Methods 0.000 claims abstract description 111
- 239000000919 ceramic Substances 0.000 claims abstract description 85
- 229910000029 sodium carbonate Inorganic materials 0.000 claims abstract description 58
- 239000012267 brine Substances 0.000 claims abstract description 43
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims abstract description 41
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 38
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 37
- 238000001914 filtration Methods 0.000 claims abstract description 34
- 238000005406 washing Methods 0.000 claims abstract description 34
- 239000011575 calcium Substances 0.000 claims abstract description 21
- 238000001035 drying Methods 0.000 claims abstract description 21
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims abstract description 9
- 238000001556 precipitation Methods 0.000 claims description 95
- 239000000243 solution Substances 0.000 claims description 48
- 239000002244 precipitate Substances 0.000 claims description 39
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 claims description 27
- 229910001425 magnesium ion Inorganic materials 0.000 claims description 27
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical group [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 claims description 19
- 239000000347 magnesium hydroxide Substances 0.000 claims description 18
- 229910001862 magnesium hydroxide Inorganic materials 0.000 claims description 18
- 239000002245 particle Substances 0.000 claims description 18
- 238000011001 backwashing Methods 0.000 claims description 17
- 239000011148 porous material Substances 0.000 claims description 15
- 239000000843 powder Substances 0.000 claims description 15
- 230000018044 dehydration Effects 0.000 claims description 14
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- 238000001354 calcination Methods 0.000 claims description 12
- 239000011734 sodium Substances 0.000 claims description 11
- 229910001424 calcium ion Inorganic materials 0.000 claims description 10
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- 238000005374 membrane filtration Methods 0.000 claims description 10
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- 125000000129 anionic group Chemical group 0.000 claims description 7
- 238000000746 purification Methods 0.000 claims description 7
- 239000002994 raw material Substances 0.000 claims description 7
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 claims description 6
- 150000002500 ions Chemical class 0.000 claims description 6
- 239000012466 permeate Substances 0.000 claims description 6
- 229910052708 sodium Inorganic materials 0.000 claims description 6
- 229940077388 benzenesulfonate Drugs 0.000 claims description 5
- 238000002360 preparation method Methods 0.000 claims description 5
- 230000035484 reaction time Effects 0.000 claims description 5
- -1 sodium alkyl benzene Chemical class 0.000 claims description 5
- 239000012141 concentrate Substances 0.000 claims description 3
- 238000009295 crossflow filtration Methods 0.000 claims description 3
- 239000011777 magnesium Substances 0.000 abstract description 21
- 239000000047 product Substances 0.000 abstract description 19
- 239000000706 filtrate Substances 0.000 abstract description 13
- 238000003825 pressing Methods 0.000 abstract description 8
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 abstract description 7
- 229910052749 magnesium Inorganic materials 0.000 abstract description 7
- 229910052791 calcium Inorganic materials 0.000 abstract description 5
- 238000010924 continuous production Methods 0.000 abstract description 4
- 238000007670 refining Methods 0.000 abstract description 4
- 239000002002 slurry Substances 0.000 abstract description 4
- 150000003839 salts Chemical class 0.000 abstract description 3
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- 238000000605 extraction Methods 0.000 abstract description 2
- 238000004806 packaging method and process Methods 0.000 abstract description 2
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- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 description 24
- 238000003756 stirring Methods 0.000 description 18
- 230000008569 process Effects 0.000 description 16
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 15
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 13
- 238000010438 heat treatment Methods 0.000 description 12
- 239000012535 impurity Substances 0.000 description 12
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- 239000000084 colloidal system Substances 0.000 description 11
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- 238000004519 manufacturing process Methods 0.000 description 10
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 8
- 239000007788 liquid Substances 0.000 description 8
- 238000011084 recovery Methods 0.000 description 8
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 6
- 239000003513 alkali Substances 0.000 description 6
- 239000004566 building material Substances 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 239000006228 supernatant Substances 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical class [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 5
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 5
- 239000000920 calcium hydroxide Substances 0.000 description 5
- 235000011116 calcium hydroxide Nutrition 0.000 description 5
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 5
- ZSYZSZTWBOHQQK-UHFFFAOYSA-L dilithium;dichloride Chemical compound [Li+].[Li+].[Cl-].[Cl-] ZSYZSZTWBOHQQK-UHFFFAOYSA-L 0.000 description 5
- 239000011541 reaction mixture Substances 0.000 description 5
- 238000004062 sedimentation Methods 0.000 description 5
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 230000032683 aging Effects 0.000 description 4
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- 150000001450 anions Chemical class 0.000 description 4
- 229910002092 carbon dioxide Inorganic materials 0.000 description 4
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- 230000000052 comparative effect Effects 0.000 description 4
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- 229910003002 lithium salt Inorganic materials 0.000 description 4
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 4
- 239000001095 magnesium carbonate Substances 0.000 description 4
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 4
- 238000001953 recrystallisation Methods 0.000 description 4
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- 229910000019 calcium carbonate Inorganic materials 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000011161 development Methods 0.000 description 3
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- 159000000002 lithium salts Chemical class 0.000 description 3
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- 238000012545 processing Methods 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 239000003463 adsorbent Substances 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 238000009993 causticizing Methods 0.000 description 2
- 239000003480 eluent Substances 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 239000011268 mixed slurry Substances 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000012465 retentate Substances 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 239000004094 surface-active agent Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 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 1
- 229910000733 Li alloy Inorganic materials 0.000 description 1
- 206010026749 Mania Diseases 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 238000005273 aeration Methods 0.000 description 1
- VMWZRHGIAVCFNS-UHFFFAOYSA-J aluminum;lithium;tetrahydroxide Chemical compound [Li+].[OH-].[OH-].[OH-].[OH-].[Al+3] VMWZRHGIAVCFNS-UHFFFAOYSA-J 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- ZFXVRMSLJDYJCH-UHFFFAOYSA-N calcium magnesium Chemical compound [Mg].[Ca] ZFXVRMSLJDYJCH-UHFFFAOYSA-N 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
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- 230000002349 favourable effect Effects 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 238000005984 hydrogenation reaction Methods 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000001989 lithium alloy Substances 0.000 description 1
- 150000002642 lithium compounds Chemical class 0.000 description 1
- GCICAPWZNUIIDV-UHFFFAOYSA-N lithium magnesium Chemical compound [Li].[Mg] GCICAPWZNUIIDV-UHFFFAOYSA-N 0.000 description 1
- 229940031958 magnesium carbonate hydroxide Drugs 0.000 description 1
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
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Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D15/00—Lithium compounds
- C01D15/08—Carbonates; Bicarbonates
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Abstract
The invention relates to a method for preparing battery-grade lithium carbonate by using industrial sodium carbonate and precipitating lithium, which belongs to the technical field of lithium extraction in salt lakes, and comprises the following steps: refining industrial sodium carbonate, adding two alkalis (sodium hydroxide and sodium carbonate) into lithium-rich brine for reaction, filtering by using a ceramic membrane to remove calcium and magnesium, reacting by using lithium carbonate, performing plate-frame filter pressing, washing by using a slurry washing tank, performing centrifugal washing, performing disc drying, damaging air flow, and packaging a finished product. The invention can realize continuous production, the removal rate of calcium and magnesium in the filtrate filtered by the ceramic membrane reaches theoretical 100 percent, and the method plays a decisive role in the lithium deposition process of lithium carbonate and reaches the industrial standard of battery-grade lithium carbonate.
Description
Technical Field
The invention relates to a method for preparing battery-grade lithium carbonate by using a membrane separation technology, and belongs to the technical field of lithium raw material preparation.
Background
Lithium and lithium salts are energy materials closely related to the life of people and strategic materials with important significance in national economy and national defense construction. Li2CO3The lithium salt is not only a raw material which is used in a large amount in the industries of ceramics, metallurgy, energy, medicine and the like, but also a basic lithium salt for preparing other high-purity lithium compounds and lithium alloys.
In recent years, with the development of new technologies, battery grade lithium carbonate used for preparing lithium ion battery positive electrode materials and electrolytes, medical lithium carbonate for treating mania, and high-purity lithium carbonate used as a solid wave body vibration element in the field of electronic materials are receiving more and more attention. China still has a gap with the international advanced level in the aspect of battery-grade lithium carbonate preparation industry, and has no strong competitiveness in the world market, and along with the high-speed development of the information industry, the market demand of lithium ion batteries is continuously expanded, the process technology research is continuously advanced, and the increase of the demand of battery-grade lithium carbonate is promoted. In order to meet the domestic and even world requirements for lithium products, improve the domestic process level for preparing battery-grade lithium carbonate, reduce the gap with the international advanced level, and improve the international competitive position of the lithium industry in China, the deep research on the preparation process of the battery-grade lithium carbonate becomes an important research and development direction of the lithium ion battery industry. Therefore, lithium carbonate plays an important role in the lithium ion battery industry, and the development of battery-grade lithium carbonate with high added value is imperative.
Due to the limitation of production technology and salt lake brine, most primary products are industrial-grade lithium carbonate with low cost and large yield, and currently domestic battery-grade lithium carbonate is mainly prepared by taking industrial-grade lithium carbonate as a raw material and performing secondary deep processing. At present, the method for preparing battery-grade lithium carbonate by taking industrial-grade lithium carbonate as a raw material mainly comprises a causticizing method, a recrystallization method, a hydrogenation precipitation method and the like.
The causticizing method is characterized in that lithium carbonate reacts with calcium hydroxide to generate lithium hydroxide, and the lithium hydroxide reacts with carbon dioxide gas to purify and prepare high-purity lithium carbonate. The specific operation is that the lithium carbonate and water are mixed according to a certain proportion and then react with hydrated lime (calcium hydroxide), so that calcium and magnesium impurities are respectively precipitated in the form of calcium carbonate and magnesium hydroxide; filtering and separating the treated suspension, transferring the obtained lithium hydroxide solution into an evaporator, evaporating and concentrating, and then introducing carbon dioxide gas to obtain Li2CO3Precipitation of (4). The method can control the impurity ions of Ga2+ and Mg2+ in the product at lower concentration. The method has high requirements on hydrated lime, otherwise, other impurities can be brought in, and the purity of the product is influenced. In addition, calcium ions can be introduced into the hydrated lime, special attention needs to be paid to control, the requirements on the conditions required by the reaction are strict, the energy consumption is high in the production process, the operation is complex, and the production period is long.
Recrystallization is a frequently used method of purifying the product in industrial production. The principle of recrystallization is to dissolve the substance to be purified in a solvent and then to recrystallize it by some method. The recrystallization can not only purify the crystal, but also change the appearance of the crystal, and the like. The method has ideal impurity removing effect, but because the solubility of the lithium carbonate in water is not high, a large amount of solvent is needed, the pollution is serious, the material flow quantity is large, and the operation is complicated.
The hydro-precipitation method combines gas-liquid reaction and liquid-liquid reaction, is favorable for controlling the purity and granularity of the product, and can fully utilize CO2The flow rate mixes the slurry. To coarse Li2CO3Introducing high-purity CO into the mixed slurry of the mixed slurry and the deionized water2A gas. Under the condition of stirring, controlling proper reaction temperature, stirring speed and CO2The LiHCO is obtained after a certain reaction time at the aeration speed3And (4) removing impurities from the solution through an exchange resin. Then reacting with high-purity LiOH to obtain a high-purity Li2CO3 product. To makeThe high-purity product is obtained by adding pure LiOH, so that the production cost is increased, and the recovery rate of the process lithium is low.
The method mainly adopts a hydrothermal method, chemical impurity removal and ion exchange, impurities in the lithium carbonate are gradually removed, and a battery-grade lithium carbonate process is obtained.
In us patent 6280693, a method for preparing lithium aluminum hydroxide adsorbent and a process for extracting lithium from brine are disclosed, wherein an eluent containing saturated sodium chloride is recycled twice or more to increase the lithium concentration to 2 mol/l. In the process, a large amount of sodium chloride is added, the operation is complex, the adsorption stock solution does not contain magnesium ions and calcium ions, the adsorbent is only used in the production of FMC in salt lake of Hombre Muerto at present, and the concentration of the raw material brine, namely, the level lithium, is higher. The method for thickening by repeatedly using the eluent is not suitable for brine with high magnesium-lithium ratio and low grade. In conclusion, the method for preparing the battery-grade lithium carbonate by directly adopting the industrial-grade sodium carbonate in the process of extracting the lithium from the salt lake has the advantages of continuous production, cleanness and cleanness, and the product reaches the industrial standard of the battery-grade lithium carbonate.
National standards for industrial lithium carbonate and industry standards for battery grade lithium carbonate are set forth in tables 1 and 2 below:
TABLE 1
TABLE 2
Disclosure of Invention
The invention relates to a method for preparing battery-grade lithium carbonate by using industrial sodium carbonate and precipitating lithium, which can effectively solve the problems of high production cost, complex operation, environmental pollution and the like caused by the fact that the battery-grade lithium carbonate cannot be directly produced by the existing salt lake lithium extraction process and further deep processing is needed.
A method for preparing battery-grade lithium carbonate by using a membrane separation technology comprises the following steps:
step 1, preparing industrial-grade sodium carbonate into a solution with the concentration of 25-35%, adding sodium hydroxide for reaction, and filtering a precipitate through a ceramic membrane to obtain a purified sodium carbonate solution;
step 2, adding sodium hydroxide and sodium carbonate into the lithium-rich brine to respectively precipitate magnesium ions and calcium ions, and filtering the precipitate through a ceramic membrane to obtain brine without divalent ions;
and 3, adding the sodium carbonate solution obtained in the step 1 into the brine obtained in the step 2 after the hard divalent ions are removed to generate lithium carbonate precipitate, and filtering out the precipitate to obtain purified lithium carbonate.
In one embodiment, the NaOH added in step 1 is 30% to 40% sodium hydroxide solution.
In one embodiment, the purified lithium carbonate obtained in step 3 is further subjected to drying and crushing.
In one embodiment, the concentrated solution obtained by ceramic membrane filtration in step 2 is dehydrated and then calcined, and the obtained CaO and MgO are used as building raw materials.
In one embodiment, in step 1 or step 2, the ceramic membrane is a membrane with an average pore diameter of 20-200 nm; the ceramic membrane filtration adopts cross flow filtration, and the flow rate of the membrane surface is 1-6 m/s.
In one embodiment, in the step 3, the addition amount of the sodium carbonate is converted according to the stoichiometric ratio, the lithium carbonate precipitation reaction temperature is 80-90 ℃, and the reaction time is 30-60 min.
In one embodiment, a precipitation aid, which is an anionic surface-treated powder, is added simultaneously with the addition of NaOH in step 2.
In one embodiment, the anionic surface-treated powder is magnesium hydroxide coated on the surface of sodium alkyl benzene sulfonate and is added in an amount of 0.1-0.5 g/L.
In one embodiment, after the ceramic membrane is filtered, a filter cake on the surface of the membrane is washed in a back washing mode to recover the flux; the pressure of the back washing is 0.4-0.6MPa, and the time of the back washing is 10-20 s.
An apparatus for preparing battery grade lithium carbonate using membrane separation technology, comprising:
the first precipitation reaction tank is used for carrying out precipitation purification treatment on industrial sodium carbonate;
the first NaOH adding tank is connected to the first precipitation reaction tank and is used for adding NaOH into the first precipitation reaction tank;
the first ceramic membrane is connected with the first precipitation reaction tank and used for filtering and removing precipitates generated in the first precipitation reaction tank;
the second precipitation reaction tank is used for carrying out precipitation purification treatment on the lithium-containing brine to generate precipitates of calcium and magnesium ions;
the second NaOH adding tank is connected to the second precipitation reaction tank and is used for adding NaOH into the second precipitation reaction tank;
Na2CO3an adding tank connected to the second precipitation reaction tank for adding Na into the second precipitation reaction tank2CO3；
The second ceramic membrane is connected with the second precipitation reaction tank and is used for filtering and removing precipitates generated in the second precipitation reaction tank;
the third precipitation reaction tank is connected to the permeation side of the second ceramic membrane and is used for carrying out lithium carbonate precipitation reaction on the brine permeate obtained from the second ceramic membrane; the permeation side of the first ceramic membrane is connected to the third precipitation reaction tank;
and the second dehydration device is connected to the third precipitation reaction tank and is used for dehydrating the precipitate obtained in the third precipitation reaction tank to obtain lithium carbonate.
In one embodiment, further comprising: and the washing tank is connected with the second dehydration device and is used for washing the lithium carbonate obtained in the second dehydration device.
In one embodiment, further comprising: and the drying device is used for drying the lithium carbonate in the washing tank.
In one embodiment, further comprising: and the crushing device is used for crushing the lithium carbonate obtained in the drying device.
In one embodiment, the method further comprises a first dehydration device connected to the retentate side of the second ceramic membrane for dehydrating the precipitate-containing concentrate obtained by the second ceramic membrane.
In one embodiment, the method further comprises a calcining furnace for calcining the precipitate obtained in the first dewatering device.
In one embodiment, the system further comprises a precipitation auxiliary particle adding tank connected to the second precipitation reaction tank and used for adding precipitation auxiliary particles into the second precipitation reaction tank.
In one embodiment, the first dewatering device or the second dewatering device is a plate and frame filter or a centrifuge.
In one embodiment, the first ceramic film or the second ceramic film has an average pore size in the range of 20 to 2000 nm.
Advantageous effects
1. The invention can directly adopt industrial sodium carbonate to prepare battery-grade lithium carbonate without adopting deep secondary processing and refining.
2. The ceramic membrane filtration can effectively remove the fine crystals of magnesium carbonate and magnesium hydroxide in the filtrate, thereby improving the purity of the product.
3. The membrane filtration adopted by the invention is ceramic membrane filtration, and the ceramic membrane has the characteristics of long service life, easy cleaning and regeneration, high temperature resistance, corrosion resistance, high strength and the like in production. And, by introducing Mg (OH) with anionic surface treatment during the precipitation of Mg2+ with NaOH2Effectively improves the grain size of generated sediment through electrostatic action, and improves the flux recovery rate of the ceramic membrane after backwashing.
4. The lithium carbonate prepared by the method reaches the industrial standard of battery-grade lithium carbonate.
5. The production process provided by the invention is simple, can realize continuous production, and is suitable for large-scale industrial production of enterprises.
Drawings
FIG. 1 is a flow chart of the present invention.
FIG. 2 is a diagram of the apparatus of the present invention.
FIG. 3 is a graph showing the particle size distribution of the precipitate retained by the ceramic membrane.
Fig. 4 is a flux recovery curve for the ceramic membrane backflushing process.
Wherein, 1, a first precipitation reaction tank; 2. a first NaOH adding tank; 3. a first ceramic film; 4. a second precipitation reaction tank; 5. a second NaOH adding tank; 6. na (Na)2CO3A feeding tank; 7. adding auxiliary particles into a tank; 8. a second ceramic film; 9. a first dewatering device; 10. a calciner; 11. a third precipitation reaction tank; 12. a second dehydration device; 13. a washing tank; 14. a drying device; 15. a crushing device.
Detailed Description
The percentages recited in the present invention are all percentages by mass unless otherwise specified.
The invention relates to a method for preparing battery-grade lithium carbonate by using industrial sodium carbonate and depositing lithium, which comprises the following steps: refining industrial sodium carbonate, adding two alkalis (sodium hydroxide and sodium carbonate) into lithium-rich brine for reaction, filtering by using a ceramic membrane to remove calcium and magnesium, reacting by using lithium carbonate, performing plate-frame filter pressing, washing by using a slurry washing tank, performing centrifugal washing, performing disc drying, damaging air flow, and packaging a finished product. The invention can realize continuous production, the removal rate of calcium and magnesium in the filtrate filtered by the ceramic membrane reaches theoretical 100 percent, and the method plays a decisive role in the lithium deposition process of lithium carbonate and reaches the industrial standard of battery-grade lithium carbonate.
The method provided by the invention is detailed as follows:
step 1, refining industrial sodium carbonate: preparing industrial sodium carbonate into 25% -35% solution, adding 30% -40% sodium hydroxide for reaction, filtering the obtained mixed solution by using a ceramic membrane to obtain refined sodium carbonate solution, wherein the industrial sodium carbonate usually contains a small amount of impurities such as sodium chloride, iron, magnesium and sulfurAcid salts, water-insoluble substances, etc., in which magnesium ions are mostly present in the form of magnesium carbonate, are known. The particle size of magnesium carbonate is very small, and the solubility product is larger than that of magnesium hydroxide, when a sodium carbonate solution passes through a general precision filter, a part of magnesium carbonate cannot be filtered and can be brought into a lithium precipitation crystallizer, so that the quality of finished lithium carbonate is influenced, in the step, the aim is to remove impurity metal ions in industrial sodium carbonate through sodium hydroxide to generate precipitates, and the impurity cations can be prevented from entering lithium carbonate to influence the purity; after treatment, Ca in the refined sodium carbonate2++Mg2+＜0.001%；
Step 2, adding two alkalis (sodium hydroxide and sodium carbonate) into the lithium-rich brine for reaction: heating lithium-rich brine in a reaction tank to 50-60 ℃, adding refined sodium carbonate for reaction, reacting for 10-30min, adding sodium hydroxide to control the pH value of 12 for reaction, and reacting for 30-60 min; in the step, the adopted brine is lithium-rich brine obtained after solar salt treatment, the concentration of lithium ions is obviously improved, and a certain amount of Ca still exists in the brine2+And Mg2+Ions, Mg (OH) can be produced by adding sodium hydroxide and sodium carbonate, respectively2Colloids and CaCO3Precipitating, adding Ca2+And Mg2+Ions are removed from the brine. Heating the lithium-rich brine in a reaction tank to 50-60 ℃, controlling the stirring speed at 150r/min, adding refined sodium carbonate for reaction, adding sodium hydroxide after the reaction is carried out for 10-30min, controlling the pH value of 12 for reaction, reacting for 30-60min, stopping stirring, and carrying out feed liquid aging for 60-120 min.
Step 3, ceramic membrane filtration: standing and settling the mixed solution reacted in the step 2, taking supernatant, filtering by using a ceramic membrane, and removing calcium and magnesium ions reacted in the filtrate to obtain a refined lithium chloride solution; the precipitates generated in the step 1 and the step 2 are removed by filtration through a ceramic membrane; the ceramic membrane filtration is realized by adopting a ceramic membrane with the membrane aperture of 0.02 mu m-0.1 mu m, the operation pressure is 0.15-0.3 MPa, and the membrane surface flow rate is 2-4 m/s. The ceramic membrane is formed by taking metal oxide as a support, coating an active layer for separation on the support, and forming an intermediate transition layer between the support and the active layer for separation. The ceramic membrane with the multilayer structure has uniform aperture and thin separation layer, and has the characteristics of long service life, easy cleaning and regeneration, high temperature resistance, corrosion resistance and high strength compared with an organic membrane; compared with a metal film, the coating has the characteristic of corrosion resistance. After the ceramic membrane is filtered, a backwashing mode is adopted to flush the filter cake on the surface of the membrane, and the flux is recovered; the pressure of the back washing is 0.4-0.6MPa, and the time of the back washing is 10-20 s.
In addition, Mg (OH) is generated in the process of carrying out double-alkali precipitation on the brine2The colloid has small particle size, high dispersibility in water, and small particle size of Mg (OH) when filtering with ceramic membrane2The colloid is easy to cause the membrane pores of the ceramic membrane to be blocked, so that when the ceramic membrane is subjected to back flush cleaning, Mg (OH) blocked in the membrane pores2The colloid is not easy to remove, so that the flux recovery rate of membrane cleaning is low; in the invention, Mg (OH) with surface anion coating treatment is added in the two-alkali precipitation process2Powder, Mg (OH) produced by direct precipitation2The surface of the colloid is mainly positively charged and can be coated with surface anion treated Mg (OH)2The powder generates electrostatic effect, and is adsorbed on the surface of the powder to cause Mg (OH)2The colloid has increased particle size, and can prevent Mg (OH) directly obtained by precipitation2The colloid is blocked in the membrane pores in the filtering process of the ceramic membrane, and the recovery rate of pure water flux can be improved after the back washing of the ceramic membrane. The above surface anion-coated Mg (OH)2The powder can be prepared by the method in the prior art, taking wet coating as an example, and Mg (OH)2The powder is mixed with an anionic surfactant and water, and then dried to obtain a coated powder. As the surfactant used herein, an element of the hydrocarbon type such as sodium alkylbenzenesulfonate is used, and the surfactant can be converted into a gaseous state after the precipitate is calcined, and Mg (OH)2Colloids and CaCO3After precipitation and calcination, MgO and CaO can be respectively generated, and the mixture can be applied to the manufacture of building materials.
During the precipitation process, a certain amount of magnesium hydroxide (which can be prepared by a wet method and is obtained by mixing magnesium hydroxide, an anionic surfactant and water and drying) subjected to anionic surface modification treatment is added at the same time. Because the surface is modified by anions, the modified magnesium hydroxide can generate electrostatic interaction with generated magnesium hydroxide precipitates, so that colloids are adsorbed on the surfaces of magnesium hydroxide particles to form larger particles, the blockage of membrane pores during subsequent solid-liquid separation membrane is avoided, and the flux attenuation of the solid-liquid separation membrane is reduced. In addition, the anionic surfactant used in the invention is mainly an anionic surfactant (such as sodium alkyl benzene sulfonate) which can contain carbon, hydrogen and sulfur, and can be removed by calcination treatment after being mixed with calcium magnesium precipitate, and the purity of calcium oxide and magnesium oxide which need to be reused later is not influenced. After the ceramic membrane is filtered, a backwashing mode is adopted to flush the filter cake on the surface of the membrane, and the flux is recovered; the pressure of the back washing is 0.4-0.6MPa, and the time of the back washing is 10-20 s.
And 5, carrying out plate-and-frame filter pressing on the mixed solution obtained in the step 3, feeding a filter cake into a slurry washing tank for washing, carrying out centrifugal washing, carrying out disc-type drying, and damaging air flow to obtain a finished product of the battery-grade lithium carbonate.
Based on the above method, the present invention further provides a device for preparing battery-grade lithium carbonate by using membrane separation technology, comprising:
the first precipitation reaction tank 1 is used for carrying out precipitation purification treatment on industrial sodium carbonate;
the first NaOH adding tank 2 is connected to the first precipitation reaction tank 1 and is used for adding NaOH into the first precipitation reaction tank 1;
the first ceramic membrane 3 is connected to the first precipitation reaction tank 1 and used for filtering and removing precipitates generated in the first precipitation reaction tank 1;
the second precipitation reaction tank 4 is used for carrying out precipitation purification treatment on the lithium-containing brine to generate precipitates of calcium and magnesium ions;
the second NaOH adding tank 5 is connected to the second precipitation reaction tank 4 and is used for adding NaOH into the second precipitation reaction tank 4;
Na2CO3an adding tank 6 connected to the second precipitation reaction tank 4 and used for adding Na into the second precipitation reaction tank 42CO3；
The second ceramic membrane 8 is connected to the second precipitation reaction tank 4 and is used for filtering and removing precipitates generated in the second precipitation reaction tank 4;
a third precipitation reaction tank 11 connected to the permeate side of the second ceramic membrane 8, for performing a lithium carbonate precipitation reaction on the brine permeate obtained from the second ceramic membrane 8; the permeate side of the first ceramic membrane 3 is connected to the third precipitation reaction tank 11;
and the second dehydration device 12 is connected to the third precipitation reaction tank 11 and is used for dehydrating the precipitate obtained in the third precipitation reaction tank 11 to obtain lithium carbonate.
In one embodiment, further comprising: and a washing tank 13 connected to the second dehydration device 12 for washing the lithium carbonate obtained in the second dehydration device 12.
In one embodiment, further comprising: and a drying device 14 for drying the lithium carbonate in the washing tank 13.
In one embodiment, further comprising: and a crushing device 14 for crushing the lithium carbonate obtained in the drying device 14.
In one embodiment, a first dewatering device 9 is further included, connected to the retentate side of the second ceramic membrane 8, for dewatering the precipitate-containing concentrate obtained from the second ceramic membrane 8.
In one embodiment, a calciner 10 is further included for subjecting the precipitate obtained in the first dewatering device 9 to a calcination process.
In one embodiment, the system further comprises a precipitation auxiliary particle adding tank 7 connected to the second precipitation reaction tank 4 for adding precipitation auxiliary particles into the second precipitation reaction tank 4.
In one embodiment, the first dewatering device 9 or the second dewatering device 12 is a plate and frame filter or a centrifuge.
In one embodiment, the first ceramic film 3 or the second ceramic film 8 has an average pore size in the range of 20 to 2000 nm.
Example 1
⑴ at 6m3Taking a reaction kettle as an example, preparing industrial sodium carbonate produced by an alkali factory into 5m of 35% solution3Heating to 50 ℃, controlling the stirring speed at 150r/min, adding 25kg of sodium hydroxide for reaction, filtering the obtained mixed solution by adopting a ceramic membrane with the membrane aperture of 0.05um, controlling the operating pressure at 0.3 MPa, controlling the membrane surface flow rate at 2m/s, and detecting the turbidity of the filtrate to be less than or equal to 0.05NTU to obtain a refined sodium carbonate solution for later use;
⑵ taking Qinghai lithium chloride lithium-rich brine 5m3，Li+At a concentration of 17.5g/l, Mg2+The concentration is 1.4g/l, the lithium-rich brine is heated in a reaction tank to 60 ℃ and added with 3m3Refined sodium carbonate (added with Ca)2+Reaction excess of 0.1g/L according to the stoichiometric ratio), controlling the stirring speed at 150r/min, adding 200kg of sodium hydroxide after reaction for 10-30min (the addition is controlled by the addition of Mg2+Excessive reaction by 0.1 g/L) according to the stoichiometric ratio, reacting at pH12 for 30min, stopping stirring, and aging the solution for 120 min;
⑶ pouring the reaction mixture of lithium-rich brine into a sedimentation tank, settling for 60min, collecting supernatant, filtering with ceramic membrane with membrane pore diameter of 0.05um, controlling operation pressure at 0.3 MPa, membrane surface flow rate of 2m/s, detecting turbidity of filtrate less than or equal to 0.05NTU to obtain purified lithium chloride solution, and measuring Ca in the solution2+：0.02ppm，Mg2+: 0.3 ppm. And (3) filtering and dehydrating the ceramic membrane concentrated solution by using a plate frame, and calcining the precipitated residues to obtain a mixture of MgO and CaO for producing the building material.
⑷, heating the purified lithium chloride solution to 90 ℃, adding refined sodium carbonate for reaction for 60min to obtain a mixed solution, performing plate-and-frame filter pressing, washing a filter cake in a pulp washing tank, performing centrifugal washing, performing disc drying, and damaging air flow to obtain a battery-grade lithium carbonate finished product with the purity of 99.61%.
Example 2
⑴ in 6m3Taking a reaction kettle as an example, preparing industrial sodium carbonate produced by an alkali factory into a 25% solution of 5m3Heating to 55 ℃, controlling the stirring speed at 150r/min, adding 25kg of sodium hydroxide for reaction, filtering the obtained mixed solution by adopting a ceramic membrane with the membrane aperture of 0.05um, controlling the operating pressure at 0.3 MPa, controlling the membrane surface flow rate at 3m/s, and detecting the turbidity of the filtrate to be less than or equal to 0.05NTU to obtain a refined sodium carbonate solution for later use;
⑵ taking Qinghai lithium chloride lithium-rich brine 5m3，Li+At a concentration of 16.8g/l, Mg2+The concentration is 1.28g/l, the lithium-rich brine is heated in a reaction tank to 60 ℃ and added with 3m3Refined sodium carbonate (added with Ca)2+Reacting at stoichiometric ratio and excessive amount of 0.1 g/L), controlling stirring speed at 150r/min, reacting for 30min, and adding 180kg sodium hydroxide (the amount of the sodium hydroxide and Mg are added)2+Reaction excess of 0.1g/L according to the stoichiometric ratio) controlling the pH value of 12 to react, wherein the reaction time is 30min, and stirring is stopped to age the feed liquid for 100 min;
⑶ pouring the reaction mixture of lithium-rich brine into a sedimentation tank, settling for 90min, collecting supernatant, filtering with ceramic membrane with membrane pore diameter of 0.05um, controlling operation pressure at 0.3 MPa, membrane surface flow rate at 3m/s, detecting turbidity of filtrate at less than or equal to 0.05NTU to obtain purified lithium chloride solution, and measuring Ca in the solution2+：0.02ppm，Mg2+: 0.5 ppm. And (3) filtering and dehydrating the ceramic membrane concentrated solution by using a plate frame, and calcining the precipitated residues to obtain a mixture of MgO and CaO for producing the building material.
⑷, heating the purified lithium chloride solution to 90 ℃, adding refined sodium carbonate for reaction for 60min to obtain a mixed solution, performing plate-and-frame filter pressing, washing a filter cake in a pulp washing tank, performing centrifugal washing, performing disc drying, and damaging air flow to obtain a battery-grade lithium carbonate finished product with the purity of 99.71%.
Example 3
The differences from example 1 are: during the process of adding NaOH to the brine for precipitation, magnesium hydroxide powder coated with sodium alkyl benzene sulfonate is also added.
⑴ at 6m3Taking a reaction kettle as an example, preparing industrial sodium carbonate produced by an alkali factory into 5m of 35% solution3Heating to 50 ℃, controlling the stirring speed at 150r/min, adding 25kg of sodium hydroxide for reaction, filtering the obtained mixed solution by adopting a ceramic membrane with the membrane aperture of 0.05um, controlling the operating pressure at 0.3 MPa, controlling the membrane surface flow rate at 2m/s, and detecting the turbidity of the filtrate to be less than or equal to 0.05NTU to obtain a refined sodium carbonate solution for later use;
⑵ taking Qinghai lithium chloride lithium-rich brine 5m3，Li+At a concentration of 17.5g/l, Mg2+The concentration is 1.4g/l, the lithium-rich brine is heated in a reaction tank to 60 ℃ and added with 3m3Refined sodium carbonate (added with Ca)2+Reacting at stoichiometric ratio and excessive amount of 0.1 g/L), controlling stirring speed at 150r/min, reacting for 10-30min, and adding 200kg sodium hydroxide (the addition amount is equal to that of Mg)2+Reaction excess of 0.1g/L according to the stoichiometric ratio) is controlled to carry out reaction at pH12, 0.1g/L sodium alkyl benzene sulfonate-coated magnesium hydroxide powder is added while sodium hydroxide is added, the reaction time is 30min, the stirring is stopped, and the feed liquid is aged for 120 min;
⑶ pouring the reaction mixture of lithium-rich brine into a sedimentation tank, settling for 60min, collecting supernatant, filtering with ceramic membrane with membrane pore diameter of 0.05um, controlling operation pressure at 0.3 MPa, membrane surface flow rate of 2m/s, detecting turbidity of filtrate less than or equal to 0.05NTU to obtain purified lithium chloride solution, and measuring Ca in the solution2+：0.02ppm，Mg2+: 0.3 ppm. And (3) filtering and dehydrating the ceramic membrane concentrated solution by using a plate frame, and calcining the precipitated residues to obtain a mixture of MgO and CaO for producing the building material.
⑷, heating the purified lithium chloride solution to 90 ℃, adding refined sodium carbonate for reaction for 60min to obtain a mixed solution, performing plate-and-frame filter pressing, washing a filter cake in a pulp washing tank, performing centrifugal washing, performing disc drying, and damaging air flow to obtain a battery-grade lithium carbonate finished product with the purity of 99.65%.
Comparative example 1
The differences from example 1 are: the industrial sodium carbonate is not treated by NaOH and is directly applied to the subsequent preparation process of the lithium carbonate.
⑴ taking Qinghai lithium chloride lithium-rich brine 5m3，Li+At a concentration of 17.5g/l, Mg2+At a concentration of 1.4g/l, theHeating lithium-rich brine in a reaction tank to 60 deg.C, adding 3m3Industrial sodium carbonate (with Ca added in quantity)2+Reaction excess of 0.1g/L according to the stoichiometric ratio), controlling the stirring speed at 150r/min, adding 200kg of sodium hydroxide after reaction for 10-30min (the addition is controlled by the addition of Mg2+Excessive reaction by 0.1 g/L) according to the stoichiometric ratio, reacting at pH12 for 30min, stopping stirring, and aging the solution for 120 min;
⑵ pouring the reaction mixture of lithium-rich brine into a sedimentation tank, settling for 60min, collecting supernatant, filtering with ceramic membrane with membrane pore diameter of 0.05um, controlling operation pressure at 0.3 MPa, membrane surface flow rate of 2m/s, detecting turbidity of filtrate less than or equal to 0.05NTU to obtain purified lithium chloride solution, and measuring Ca in the solution2+：0.02ppm，Mg2+: 0.3 ppm. And (3) filtering and dehydrating the ceramic membrane concentrated solution by using a plate frame, and calcining the precipitated residues to obtain a mixture of MgO and CaO for producing the building material.
⑶, heating the purified lithium chloride solution to 90 ℃, adding refined sodium carbonate for reaction for 60min to obtain a mixed solution, performing plate-and-frame filter pressing, washing a filter cake in a pulp washing tank, performing centrifugal washing, performing disc drying, and damaging air flow to obtain a battery-grade lithium carbonate finished product with the purity of 99.20%.
Comparative example 2
The differences from example 3 are: adding conventional magnesium hydroxide powder in the process of adding NaOH to precipitate brine.
⑴ at 6m3Taking a reaction kettle as an example, preparing industrial sodium carbonate produced by an alkali factory into 5m of 35% solution3Heating to 50 ℃, controlling the stirring speed at 150r/min, adding 25kg of sodium hydroxide for reaction, filtering the obtained mixed solution by adopting a ceramic membrane with the membrane aperture of 0.05um, controlling the operating pressure at 0.3 MPa, controlling the membrane surface flow rate at 2m/s, and detecting the turbidity of the filtrate to be less than or equal to 0.05NTU to obtain a refined sodium carbonate solution for later use;
⑵ taking Qinghai lithium chloride lithium-rich brine 5m3，Li+At a concentration of 17.5g/l, Mg2+The concentration is 1.4g/l, the lithium-rich brine is heated in a reaction tank to 60 ℃ and added with 3m3Refined sodium carbonate (added with Ca)2+According to the chemical scaleCalculating the reaction excess of 0.1 g/L), controlling the stirring speed at 150r/min, reacting for 10-30min, and adding 200kg of sodium hydroxide (the addition is the addition of Mg)2+Reaction excess of 0.1g/L according to the stoichiometric ratio) and controlling the pH value of 12 to react, adding 0.1g/L magnesium hydroxide powder while adding sodium hydroxide, reacting for 30min, stopping stirring, and ageing the feed liquid for 120 min;
⑶ pouring the reaction mixture of lithium-rich brine into a sedimentation tank, settling for 60min, collecting supernatant, filtering with ceramic membrane with membrane pore diameter of 0.05um, controlling operation pressure at 0.3 MPa, membrane surface flow rate of 2m/s, detecting turbidity of filtrate less than or equal to 0.05NTU to obtain purified lithium chloride solution, and measuring Ca in the solution2+：0.02ppm，Mg2+: 0.3 ppm. And (3) filtering and dehydrating the ceramic membrane concentrated solution by using a plate frame, and calcining the precipitated residues to obtain a mixture of MgO and CaO for producing the building material.
⑷, heating the purified lithium chloride solution to 90 ℃, adding refined sodium carbonate for reaction for 60min to obtain a mixed solution, performing plate-and-frame filter pressing, washing a filter cake in a pulp washing tank, performing centrifugal washing, performing disc drying, and damaging air flow to obtain a battery-grade lithium carbonate finished product with the purity of 99.63%.
Comparative analysis of purity of lithium carbonate obtained by production
The purity of the lithium carbonate prepared in each of the above examples and comparative examples and the content of magnesium as an impurity therein were as shown in the following table:
as can be seen from the comparison between example 1 and comparative example 1 in the table, the method of the present invention, which uses the industrial sodium carbonate subjected to NaOH precipitation purification and then applies it to the precipitation process of lithium carbonate, can significantly increase the content of lithium carbonate finally obtained, from 99.2% to 99.61%, and the content of Mg2+ impurity therein is also significantly reduced, from 0.036% to 0.002%, which meets the standard of battery grade lithium carbonate.
Analysis of ceramic Membrane operating Process
All the above mentionedIn the examples, NaOH and Na are added2CO3For Mg2+And Ca2+After the precipitation reaction, the ceramic membrane is used to perform cross-flow filtration on the precipitate, and the precipitate in the concentrated solution is taken to perform particle size analysis, as shown in fig. 3, it can be seen from the figure that the particle size of the precipitate obtained in example 3 is about 15.4um, while the particle size of the precipitate in example 1 is about 4.1um, which confirms that when magnesium hydroxide treated by anionic surface is used as a precipitation auxiliary agent, magnesium hydroxide colloid generated in the precipitation process can be attracted by electrostatic action, so that the particle size of the precipitate is increased.
After the ceramic membrane is operated for 60min, the ceramic membrane is subjected to one-time back washing, and the flux recovery condition of the back washing is shown in fig. 4, wherein the back washing effect in the embodiment 3 is the best, the flux is recovered by 92%, while the flux recovery rate in the embodiment 1 is not high and is only 74%, mainly because the magnesium hydroxide colloid with smaller particle size blocks the membrane pores, and the magnesium hydroxide powder is directly added in the comparison example 2, and because the magnesium hydroxide powder cannot play a role in electrostatic adsorption, the flux recovery rate is about 78%, and is not obviously improved.
Claims (9)
1. A method for preparing battery-grade lithium carbonate by using a membrane separation technology is characterized by comprising the following steps:
step 1, preparing industrial-grade sodium carbonate into a solution with the concentration of 25-35%, adding sodium hydroxide for reaction, and filtering a precipitate through a ceramic membrane to obtain a purified sodium carbonate solution;
step 2, adding sodium hydroxide and sodium carbonate into the lithium-rich brine to respectively precipitate magnesium ions and calcium ions, and filtering the precipitate through a ceramic membrane to obtain brine without divalent ions;
and 3, adding the sodium carbonate solution obtained in the step 1 into the brine obtained in the step 2 after the hard divalent ions are removed to generate lithium carbonate precipitate, and filtering out the precipitate to obtain purified lithium carbonate.
2. The method for preparing battery grade lithium carbonate by using a membrane separation technology according to claim 1, wherein, in one embodiment, the NaOH added in the step 1 is 30-40% sodium hydroxide solution; in one embodiment, the purified lithium carbonate obtained in step 3 is further subjected to drying and crushing;
the method for preparing battery grade lithium carbonate by using the membrane separation technology according to claim 1, wherein, in one embodiment, the concentrated solution obtained by the ceramic membrane filtration in the step 2 is dehydrated and then calcined, and the obtained CaO and MgO are used as building raw materials.
3. The method for preparing battery grade lithium carbonate by using membrane separation technology according to claim 1, wherein in step 1 or step 2, the ceramic membrane is a membrane with an average pore diameter of 20-200 nm; the ceramic membrane filtration adopts cross flow filtration, and the flow rate of the membrane surface is 1-6 m/s; in one embodiment, in the step 3, the addition amount of the sodium carbonate is converted according to the stoichiometric ratio, the lithium carbonate precipitation reaction temperature is 80-90 ℃, and the reaction time is 30-60 min; in one embodiment, a precipitation aid is added simultaneously with the addition of NaOH in step 2, wherein the precipitation aid is an anionic surface-treated powder; in one embodiment, the anionic surface-treated powder is magnesium hydroxide coated on the surface of sodium alkyl benzene sulfonate and is added in an amount of 0.1-0.5 g/L.
4. The method for preparing battery-grade lithium carbonate by using a membrane separation technology according to claim 1, wherein in one embodiment, after the ceramic membrane filtration, a filter cake on the surface of the membrane is washed by a back washing method to recover the flux; the pressure of the back washing is 0.4-0.6MPa, and the time of the back washing is 10-20 s.
5. An apparatus for preparing battery-grade lithium carbonate by using a membrane separation technique, comprising:
the first precipitation reaction tank (1) is used for carrying out precipitation purification treatment on industrial sodium carbonate;
the first NaOH adding tank (2) is connected to the first precipitation reaction tank (1) and is used for adding NaOH into the first precipitation reaction tank (1);
the first ceramic membrane (3) is connected with the first precipitation reaction tank (1) and is used for filtering and removing precipitates generated in the first precipitation reaction tank (1);
the second precipitation reaction tank (4) is used for carrying out precipitation purification treatment on the lithium-containing brine to generate precipitates of calcium and magnesium ions;
the second NaOH adding tank (5) is connected to the second precipitation reaction tank (4) and is used for adding NaOH into the second precipitation reaction tank (4);
Na2CO3an adding tank (6) connected to the second precipitation reaction tank (4) and used for adding Na into the second precipitation reaction tank (4)2CO3；
The second ceramic membrane (8) is connected with the second precipitation reaction tank (4) and is used for filtering and removing precipitates generated in the second precipitation reaction tank (4);
the third precipitation reaction tank (11) is connected to the permeation side of the second ceramic membrane (8) and is used for carrying out lithium carbonate precipitation reaction on the brine permeate obtained from the second ceramic membrane (8); the permeate side of the first ceramic membrane (3) is connected to a third precipitation reaction tank (11);
and the second dehydration device (12) is connected to the third precipitation reaction tank (11) and is used for dehydrating the precipitate obtained in the third precipitation reaction tank (11) to obtain lithium carbonate.
6. The apparatus for preparing battery grade lithium carbonate using membrane separation technology according to claim 6, further comprising, in one embodiment: a washing tank (13) connected to the second dehydration device (12) and used for washing the lithium carbonate obtained in the second dehydration device (12); in one embodiment, further comprising: and a drying device (14) for drying the lithium carbonate in the washing tank (13).
7. The apparatus for preparing battery grade lithium carbonate using membrane separation technology according to claim 6, further comprising, in one embodiment: a crushing device (14) for crushing the lithium carbonate obtained in the drying device (14); in one embodiment, the device further comprises a first dehydration device (9) connected to the interception side of the second ceramic membrane (8) and used for dehydrating the concentrate containing the precipitate obtained by the second ceramic membrane (8); in one embodiment, the device further comprises a calcining furnace (10) for calcining the precipitate obtained in the first dewatering device (9).
8. The apparatus for preparing battery grade lithium carbonate by using membrane separation technology according to claim 6, characterized in that, in one embodiment, the apparatus further comprises a precipitation auxiliary particle feeding tank (7) connected to the second precipitation reaction tank (4) for feeding precipitation auxiliary particles into the second precipitation reaction tank (4); in one embodiment, the first dehydration device (9) or the second dehydration device (12) is a plate-and-frame filter or a centrifuge; in one embodiment, the first ceramic film (3) or the second ceramic film (8) has an average pore size in the range of 20 to 2000 nm.
9. Use of the device of claim 6 for the preparation of battery grade sodium carbonate.
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