CN118125473A - Method for preparing high-purity potassium sulfate from lithium precipitation mother liquor - Google Patents
Method for preparing high-purity potassium sulfate from lithium precipitation mother liquor Download PDFInfo
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- CN118125473A CN118125473A CN202410162286.7A CN202410162286A CN118125473A CN 118125473 A CN118125473 A CN 118125473A CN 202410162286 A CN202410162286 A CN 202410162286A CN 118125473 A CN118125473 A CN 118125473A
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- glaserite
- sulfate
- mother liquor
- sodium chloride
- separating
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 90
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 90
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 title claims abstract description 83
- 229910052939 potassium sulfate Inorganic materials 0.000 title claims abstract description 83
- 235000011151 potassium sulphates Nutrition 0.000 title claims abstract description 83
- 238000001556 precipitation Methods 0.000 title claims abstract description 80
- 239000012452 mother liquor Substances 0.000 title claims abstract description 60
- 238000000034 method Methods 0.000 title claims abstract description 51
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 154
- 239000011780 sodium chloride Substances 0.000 claims abstract description 77
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims abstract description 72
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims abstract description 70
- 229910052938 sodium sulfate Inorganic materials 0.000 claims abstract description 67
- 235000011152 sodium sulphate Nutrition 0.000 claims abstract description 67
- 239000010413 mother solution Substances 0.000 claims abstract description 55
- 239000001103 potassium chloride Substances 0.000 claims abstract description 36
- 235000011164 potassium chloride Nutrition 0.000 claims abstract description 36
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 34
- 238000001704 evaporation Methods 0.000 claims abstract description 33
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims abstract description 32
- 229910052808 lithium carbonate Inorganic materials 0.000 claims abstract description 32
- 238000001816 cooling Methods 0.000 claims abstract description 21
- 239000002994 raw material Substances 0.000 claims abstract description 9
- 239000000243 solution Substances 0.000 claims description 47
- 239000013078 crystal Substances 0.000 claims description 28
- 239000002002 slurry Substances 0.000 claims description 25
- INHCSSUBVCNVSK-UHFFFAOYSA-L lithium sulfate Inorganic materials [Li+].[Li+].[O-]S([O-])(=O)=O INHCSSUBVCNVSK-UHFFFAOYSA-L 0.000 claims description 21
- 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 claims description 21
- 239000000203 mixture Substances 0.000 claims description 17
- 230000008020 evaporation Effects 0.000 claims description 13
- 238000002425 crystallisation Methods 0.000 claims description 11
- 230000008025 crystallization Effects 0.000 claims description 11
- 238000000926 separation method Methods 0.000 claims description 11
- 239000007787 solid Substances 0.000 claims description 9
- 239000002253 acid Substances 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 7
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 4
- 238000005262 decarbonization Methods 0.000 claims description 3
- 239000000126 substance Substances 0.000 abstract description 6
- 239000006227 byproduct Substances 0.000 abstract description 3
- 239000010446 mirabilite Substances 0.000 abstract description 3
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 18
- 239000000047 product Substances 0.000 description 11
- 230000001376 precipitating effect Effects 0.000 description 9
- 229910000029 sodium carbonate Inorganic materials 0.000 description 9
- 239000002244 precipitate Substances 0.000 description 8
- 238000001035 drying Methods 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- 238000003763 carbonization Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 229910001416 lithium ion Inorganic materials 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- -1 Na + Chemical compound 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 238000005261 decarburization Methods 0.000 description 2
- 239000003814 drug Substances 0.000 description 2
- 239000003337 fertilizer Substances 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- HQRPHMAXFVUBJX-UHFFFAOYSA-M lithium;hydrogen carbonate Chemical compound [Li+].OC([O-])=O HQRPHMAXFVUBJX-UHFFFAOYSA-M 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 206010020772 Hypertension Diseases 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000002537 cosmetic Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000003721 gunpowder Substances 0.000 description 1
- 208000019622 heart disease Diseases 0.000 description 1
- 208000017169 kidney disease Diseases 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 210000000214 mouth Anatomy 0.000 description 1
- 235000015097 nutrients Nutrition 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229940072033 potash Drugs 0.000 description 1
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Substances [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 1
- 235000015320 potassium carbonate Nutrition 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 238000002076 thermal analysis method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
- C01D5/06—Preparation of sulfates by double decomposition
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
- C01D5/16—Purification
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
The invention discloses a method for preparing high-purity potassium sulfate by using lithium precipitation mother liquor, and belongs to the technical field of chemical industry. The method takes primary lithium precipitation mother liquor for producing lithium carbonate by a sulfuric acid method as a raw material, and comprises the following steps: decarbonizing the primary lithium precipitation mother liquor, evaporating and concentrating, cooling the concentrated mother liquor, and separating out glaserite; cooling the mother solution after separating glaserite, and separating sodium sulfate; adding potassium chloride into sodium sulfate, reacting to generate glaserite and sodium chloride, and separating sodium chloride; combining the glaserite separated from the sodium chloride with the glaserite separated from the mother liquor; then adding potassium chloride to react, and separating the generated potassium sulfate and sodium chloride to obtain sodium chloride and potassium sulfate. According to the invention, primary lithium precipitation mother liquor is used as a raw material, glaserite is precipitated firstly, sodium sulfate is precipitated secondly, na +、K+ is separated from the mother liquor, and then battery-grade lithium carbonate can be obtained; and the byproduct high-purity sodium sulfate and glauber salt are utilized to prepare the high-purity potassium sulfate. The invention realizes the full utilization of resources and has good economic value.
Description
Technical Field
The invention belongs to the technical field of chemical industry, and particularly relates to a method for preparing high-purity potassium sulfate from lithium precipitation mother liquor.
Background
The process for extracting lithium from lithium ore is mainly lime method and sulfuric acid method. The sulfuric acid process is to react metal oxide in lithium ore with sulfuric acid to produce sulfate and to obtain acidified clinker. And (3) performing primary lithium precipitation after operations such as pulping, impurity removal and the like on the acidified clinker, and refining the precipitation to obtain the lithium carbonate. The mother solution after primary lithium precipitation contains part of lithium ions and impurities such as Na +、K+.
Potassium sulfate is an important chemical and widely used in the fields of agriculture, chemical industry, medicine and the like. If used as a high-quality chlorine-free potash fertilizer, the sulfur element contained in the fertilizer has small hygroscopicity and is a medium-amount nutrient element required by plants. In industry, potassium sulfate can be used for manufacturing chemical products such as glass, phosphate, dye, pigment, gunpowder and the like. In addition, industrial potassium sulfate can also be used for manufacturing electronic chemicals such as batteries, electrolytes, electroplating solutions and the like. Industrial potassium sulfate is an important pharmaceutical raw material and can be used for manufacturing products such as medicines, cosmetics, oral cleaners and the like. It can be used for treating hypertension, heart disease, kidney disease, etc., and can also be used for cleaning oral cavity, caring skin, etc. The potassium sulfate yield in China is low, the potassium sulfate is mainly imported, and the price is high.
Therefore, the method can recover lithium ions from the mother solution after primary lithium precipitation, and can prepare high-purity potassium sulfate, and the method becomes a problem to be solved by the person skilled in the art.
Disclosure of Invention
The invention aims to provide a method for preparing high-purity potassium sulfate from lithium precipitation mother liquor, which not only can recover lithium ions from the mother liquor after primary lithium precipitation, but also can prepare high-purity potassium sulfate.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
The invention discloses a method for preparing high-purity potassium sulfate by using lithium precipitation mother liquor, which comprises the following steps: the primary lithium precipitation mother liquor for producing lithium carbonate by a sulfuric acid method is used as a raw material, and the method comprises the following steps:
s1, decarburizing and evaporating: decarbonizing the primary lithium precipitation mother liquor, and then evaporating and concentrating;
s2, separating glaserite: cooling the mother solution after evaporation and concentration, and separating out glaserite;
s3, separating sodium sulfate: cooling the mother solution after separating glaserite, and separating sodium sulfate;
S4, sodium sulfate reacts to generate glaserite: adding a potassium chloride solution into the sodium sulfate separated in the step S3, and heating to react to generate glaserite and sodium chloride;
s5, separating sodium chloride: separating the glaserite and sodium chloride mixture generated in the step S4 to obtain sodium chloride and glaserite;
s6, converting the potassium chloride to prepare potassium sulfate: combining the glaserite separated from the sodium chloride in the step S5 with the glaserite obtained in the step S2; adding potassium chloride solution to react to generate potassium sulfate and sodium chloride;
S7, separating sodium chloride: and (3) separating the mixture of potassium sulfate and sodium chloride generated in the step (S6) to obtain sodium chloride and potassium sulfate respectively.
The method takes primary lithium precipitation mother liquor as a raw material to recover lithium and prepare high-purity potassium sulfate, and the applicant surprisingly found that Na +、K+ can be effectively separated from the mother liquor by a method of firstly precipitating glaserite and then precipitating sodium sulfate, so that battery-grade lithium carbonate can be obtained after the method; and the byproduct high-purity sodium sulfate and glauber salt are utilized to prepare the high-purity potassium sulfate.
In some embodiments of the present invention, the primary lithium precipitation mother liquor has a lithium sulfate content of 7wt.% or less, a sodium sulfate content of 5-27wt.%, and a potassium sulfate content of 8-19wt.%.
In some embodiments of the present invention, in the step S1, an acid solution is added to the primary lithium precipitation mother liquor to remove carbonate; preferably, adding an acid solution to enable the pH value of the primary lithium precipitation mother solution to be 4-8; more preferably, the acid solution is a sulfuric acid solution;
Preferably, the mother solution after decarbonization is concentrated by an MVR high-efficiency evaporator, and more preferably, the concentration of lithium sulfate is more than or equal to 30g/L.
In some embodiments of the present invention, in the step S2, the mother solution after evaporation and concentration is cooled to 25±5 ℃, and glaserite is separated out, and the glaserite crystal slurry is separated through liquid-solid separation.
In some embodiments of the present invention, in the step S3, the mother solution after separating glaserite is cooled to be less than or equal to 0 ℃, sodium sulfate is separated out, and sodium sulfate crystal slurry is separated out through liquid-solid separation.
In some embodiments of the present invention, in step S4, adding an equimolar amount of potassium chloride solution to the sodium sulfate separated in step S3, and reacting to produce glaserite and sodium chloride;
preferably, the mass concentration of the potassium chloride solution is 5-10%;
preferably, the reaction temperature is 80 to 100 ℃.
In some embodiments of the invention, sodium chloride is separated in step S5: and (3) cooling the glaserite and sodium chloride generated in the step (S4) to-5-0 ℃, crystallizing and separating the glaserite, and evaporating and crystallizing to separate the sodium chloride. .
In some embodiments of the present invention, in the step S6, according to the total amount of sulfate radical in the combined glaserite, an equimolar potassium chloride solution is added to react to generate potassium sulfate and sodium chloride;
preferably, the mass concentration of the potassium chloride solution is 5-10%;
preferably, the reaction temperature is 25 to 50 ℃.
In some embodiments of the present invention, in the step S7, the mixture of potassium sulfate and sodium chloride generated in the step S6 is cooled to-5 to 0 ℃, potassium sulfate is separated by crystallization, and sodium chloride is separated by evaporation and crystallization.
In some embodiments of the invention, the process produces potassium sulfate having a purity of greater than 99%.
In some embodiments of the present invention, the method further comprises step S8: adding sodium carbonate into the mother solution after separating sodium sulfate, heating, and secondarily precipitating lithium; preferably, adding excessive sodium carbonate into the mother solution after separating sodium sulfate; more preferably, the sodium carbonate is added in an amount of 5 to 10% by weight based on the lithium sulfate concentration; preferably, the temperature is raised to be more than or equal to 90 ℃ and lithium is secondarily precipitated.
In some embodiments of the invention, the mother liquor after secondary lithium precipitation is returned and combined with the primary lithium precipitation mother liquor, and steps S1-S8 are circulated.
In some embodiments of the invention, the secondary lithium precipitation precipitate is stirred, washed, carbonized and thermally separated to obtain the battery grade lithium carbonate. Wherein, stirring and washing and carbonization heat analysis are all the prior art.
The content of lithium carbonate in the precipitate obtained by secondary lithium precipitation is more than or equal to 90 wt%.
Compared with the prior art, the invention has the following beneficial effects:
The invention has scientific design and ingenious conception, creatively utilizes the primary lithium precipitation mother liquor for producing lithium carbonate by a sulfuric acid method as a raw material, and can effectively separate Na +、K+ from the mother liquor by a method of firstly precipitating glaserite and then precipitating sodium sulfate so as to obtain battery-grade lithium carbonate after the method; and the byproduct high-purity sodium sulfate and glauber salt are utilized to prepare the high-purity potassium sulfate. The invention realizes the full utilization of resources, has good economic value and is worth popularizing and applying.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
A method for preparing high-purity potassium sulfate by using lithium precipitation mother liquor comprises the following steps: the primary lithium precipitation mother liquor for producing lithium carbonate by a sulfuric acid method is used as a raw material, and the method comprises the following steps:
s1, decarburizing and evaporating: decarbonizing the primary lithium precipitation mother liquor, and then evaporating and concentrating;
the lithium sulfate content in the primary lithium precipitation mother liquor is less than or equal to 7 wt%, the sodium sulfate content is 5-27 wt%, and the potassium sulfate content is 8-19 wt%.
Preferably, adding an acid solution into the primary lithium precipitation mother liquor to enable the pH value to be 4-8 so as to remove carbonate radicals; the acid solution is preferably a sulfuric acid solution;
Preferably, the mother solution after decarbonization is evaporated and concentrated by an MVR high-efficiency evaporator, and more preferably, the concentration of lithium sulfate is more than or equal to 30g/L.
S2, separating glaserite: and cooling the mother solution after evaporation and concentration by 25+/-5 ℃, separating out glaserite, and separating liquid and solid to obtain glaserite crystal slurry.
S3, separating sodium sulfate: and cooling the mother solution from which the glaserite is separated to less than or equal to 0 ℃, separating out sodium sulfate, and separating out sodium sulfate crystal slurry through liquid-solid separation.
S4, sodium sulfate reacts to generate glaserite: adding a molar amount of potassium chloride solution into the sodium sulfate separated in the step S3, and reacting to generate glaserite and sodium chloride;
Preferably, the mass concentration of the potassium chloride solution is 5-10%; preferably, the reaction temperature is 80 to 100 ℃.
S5, separating sodium chloride: separating the glaserite and sodium chloride mixture generated in the step S4 to obtain sodium chloride and glaserite;
Preferably, the mixture of glaserite and sodium chloride is cooled to-5-0 ℃, glaserite is separated by crystallization, and sodium chloride is separated by evaporation and crystallization.
S6, converting the potassium chloride to prepare potassium sulfate: combining the glaserite separated from the sodium chloride in the step S5 with the glaserite obtained in the step S2; adding equimolar potassium chloride solution according to the total amount of sulfate radicals in the combined glaserite to react to generate potassium sulfate and sodium chloride;
Preferably, the mass concentration of the potassium chloride solution is 5-10%; preferably, the reaction temperature is 25 to 50 ℃.
S7, separating sodium chloride: and (3) separating the mixture of potassium sulfate and sodium chloride generated in the step (S6) to obtain sodium chloride and potassium sulfate respectively, and drying to obtain a potassium sulfate product.
Preferably, the mixture of sodium chloride and potassium sulfate is cooled to-5 to 0 ℃, potassium sulfate is separated by crystallization, and sodium chloride is separated by evaporation and crystallization.
The crystal slurry of potassium sulfate separated by crystallization is dehydrated and dried, and the purity of the obtained potassium sulfate product is more than 99 percent.
In some embodiments of the present invention, the method further includes step S8: adding sodium carbonate into the mother solution after separating sodium sulfate, heating, and secondarily precipitating lithium; preferably, adding excessive sodium carbonate into the mother solution after separating sodium sulfate; more preferably, the sodium carbonate is added in an amount of 5 to 10% by weight based on the lithium sulfate concentration; preferably, the temperature is raised to be more than or equal to 80 ℃, and lithium is secondarily precipitated.
Preferably, the mother solution after secondary lithium precipitation is returned to be combined with the primary lithium precipitation mother solution, and the steps S1-S8 are circulated.
In some embodiments of the invention, the secondary lithium precipitation precipitate is stirred, washed, carbonized and thermally separated to obtain the battery grade lithium carbonate. Wherein, stirring and washing and carbonization heat analysis are all the prior art.
The content of lithium carbonate in the precipitate obtained by secondary lithium precipitation is more than or equal to 90 wt%.
Example 1
The embodiment discloses a method for preparing high-purity potassium sulfate by using a lithium precipitation mother solution, which takes a primary lithium precipitation mother solution for producing lithium carbonate by a sulfuric acid method as a raw material, wherein the primary lithium precipitation mother solution contains 6.5wt.% of lithium sulfate, 26.8wt.% of sodium sulfate and 12wt.% of potassium sulfate; the specific steps of the method of the embodiment are as follows:
S1, decarburizing and evaporating: and taking primary lithium precipitation mother liquor, adding sulfuric acid solution into the primary lithium precipitation mother liquor, and adjusting the pH value of the primary lithium precipitation mother liquor to be 4, so that carbonic acid radicals in the primary lithium precipitation mother liquor are generated and discharged, and the carbonic acid radicals are removed. And evaporating and concentrating the decarbonized mother liquor by an MVR high-efficiency evaporator until the concentration of lithium sulfate is 30.5g/L.
S2, separating glaserite: cooling the mother solution after evaporation and concentration to 25 ℃, separating out glaserite, and carrying out solid-liquid separation on glaserite crystal slurry and the mother solution; after separating out glaserite, the concentration of lithium sulfate in the mother solution is increased to 36.4g/L;
S3, separating sodium sulfate: cooling the mother solution after separating glaserite to-1-0 ℃, separating out sodium sulfate, and separating out sodium sulfate crystal slurry through liquid-solid separation; after separating out sodium sulfate crystal slurry, the concentration of sodium sulfate in the mother liquor is reduced to below 50 g/L; the concentration of lithium sulfate is increased to 82.8g/L;
and drying the sodium sulfate crystal slurry to obtain a sodium sulfate product with the purity of 88.6 percent.
S4, sodium sulfate reacts to generate glaserite: adding a molar amount of potassium chloride solution into the sodium sulfate separated in the step S3, and reacting at 100 ℃ to generate glaserite and sodium chloride, wherein the concentration of the potassium chloride solution is 10wt.%.
S5, separating sodium chloride: and (3) cooling the mixture of the glaserite and the sodium chloride generated in the step (S4) to-5-0 ℃, crystallizing and separating the glaserite, and evaporating and crystallizing to separate the sodium chloride.
S6, converting the potassium chloride to prepare potassium sulfate: combining the glaserite separated from the sodium chloride in the step S5 with the glaserite obtained in the step S2; adding an equimolar potassium chloride solution according to the total amount of sulfate radicals in the combined glaserite to react at 50 ℃ to generate potassium sulfate and sodium chloride; the concentration of the potassium chloride solution was 10wt.%
S7, separating sodium chloride: and (3) cooling the mixture of potassium sulfate and sodium chloride generated in the step (S6) to-5-0 ℃, crystallizing and separating potassium sulfate, and evaporating and crystallizing to separate sodium chloride.
The crystal separated potassium sulfate crystal slurry is dehydrated and dried, and the purity of the obtained potassium sulfate product is 99.1 percent.
S8, secondary lithium precipitation: according to the concentration of lithium sulfate in the mother solution after separating the sodium sulfate crystal slurry, adding 5% excessive sodium carbonate into the mother solution, heating to 90 ℃, and secondarily precipitating lithium. And returning the mother solution after secondary lithium precipitation, combining with the primary lithium precipitation mother solution, and circulating the steps S1-S8.
The precipitate obtained by secondary precipitation of lithium is crude lithium carbonate, and the purity of the crude lithium carbonate is about 92.4%.
Stirring and washing the crude lithium carbonate, and performing carbonization and thermal analysis to obtain battery-grade lithium carbonate, wherein the method comprises the following steps of: after adding water into the crude lithium carbonate, stirring and mixing, introducing carbon dioxide gas into the mixed solution, and reacting for 3 hours to convert the lithium carbonate into lithium bicarbonate for dissolution. Filtering the solution and separating insoluble impurities; the filtrate was warmed to 90 ℃ to decompose lithium bicarbonate to lithium carbonate. And filtering the reaction solution, collecting the precipitate, and drying to obtain the battery grade lithium carbonate.
Example 2
The embodiment discloses a method for preparing high-purity potassium sulfate by using a primary lithium precipitation mother solution for producing lithium carbonate by a sulfuric acid method, wherein the primary lithium precipitation mother solution contains 5.9wt.% of lithium sulfate, 5.0wt.% of sodium sulfate and 19.2wt.% of potassium sulfate; the specific steps of the method of the embodiment are as follows:
s1, decarburizing and evaporating: and taking primary lithium precipitation mother liquor, adding sulfuric acid solution into the primary lithium precipitation mother liquor, and adjusting the pH value of the primary lithium precipitation mother liquor to 8, so that carbonic acid radicals in the primary lithium precipitation mother liquor are generated and discharged, and the carbonic acid radicals are removed. And evaporating and concentrating the mother solution after decarburization by an MVR high-efficiency evaporator until the concentration of lithium sulfate is 30.3g/L.
S2, separating glaserite: cooling the mother solution after evaporation and concentration to 20 ℃, separating out glaserite, and carrying out solid-liquid separation on glaserite crystal slurry and the mother solution; after separating out glaserite, the concentration of lithium sulfate in the mother solution is increased to 39.9g/L;
s3, separating sodium sulfate: cooling the mother solution after separating glaserite to less than 0 ℃, separating out sodium sulfate, and separating out sodium sulfate crystal slurry through liquid-solid separation; after separating out sodium sulfate crystal slurry, the concentration of sodium sulfate in the mother liquor is reduced to below 50 g/L;
and drying the sodium sulfate crystal slurry to obtain a sodium sulfate product with the purity of more than 87.0 percent.
S4, sodium sulfate reacts to generate glaserite: adding a molar amount of potassium chloride solution into the sodium sulfate separated in the step S3, and reacting at 80 ℃ to generate glaserite and sodium chloride, wherein the concentration of the potassium chloride solution is 5wt.%.
S5, separating sodium chloride: and (3) cooling the mixture of the glaserite and the sodium chloride generated in the step (S4) to-5-0 ℃, crystallizing and separating the glaserite, and evaporating and crystallizing to separate the sodium chloride. .
S6, converting the potassium chloride to prepare potassium sulfate: combining the glaserite separated from the sodium chloride in the step S5 with the glaserite obtained in the step S2; adding equimolar potassium chloride solution according to the total amount of sulfate radicals in the combined glaserite, and reacting at 25 ℃ to generate potassium sulfate and sodium chloride, wherein the concentration of the potassium chloride solution is 5wt.%.
S7, separating sodium chloride: and (3) cooling the mixture of potassium sulfate and sodium chloride generated in the step (S6) to-5-0 ℃, crystallizing and separating potassium sulfate, and evaporating and crystallizing to separate sodium chloride. .
The crystal separated potassium sulfate crystal slurry is dehydrated and dried, and the purity of the obtained potassium sulfate product is 99.2 percent.
S8, secondary lithium precipitation: and adding 10% excessive sodium carbonate into the mother solution after separating the sodium sulfate crystal slurry according to the concentration of lithium sulfate in the mother solution, heating to 92 ℃ and secondarily precipitating lithium. And returning the mother solution after secondary lithium precipitation, combining with the primary lithium precipitation mother solution, and circulating the steps S1-S8.
The precipitate obtained by secondary precipitation of lithium is crude lithium carbonate, and the purity of the crude lithium carbonate is about 91.8%.
The crude lithium carbonate was purified as in example 1 to obtain battery grade lithium carbonate.
Example 3
The embodiment discloses a method for preparing high-purity potassium sulfate by using a primary lithium precipitation mother solution for producing lithium carbonate by a sulfuric acid method, wherein the primary lithium precipitation mother solution contains 7.0wt.% of lithium sulfate, 14.5wt.% of sodium sulfate and 8.3wt.% of potassium sulfate; the specific steps of the method of the embodiment are as follows:
S1, decarburizing and evaporating: and taking primary lithium precipitation mother liquor, adding sulfuric acid solution into the primary lithium precipitation mother liquor, adjusting the pH value of the primary lithium precipitation mother liquor to 7, and discharging carbon dioxide generated by carbonate in the primary lithium precipitation mother liquor so as to remove carbonate. And evaporating and concentrating the mother solution after decarburization by an MVR high-efficiency evaporator until the concentration of lithium sulfate is 30.1g/L.
S2, separating glaserite: cooling the mother solution after evaporation and concentration to 30 ℃, separating out glaserite, and carrying out solid-liquid separation on glaserite crystal slurry and the mother solution; after separating out glaserite, the concentration of lithium sulfate in the mother solution is increased to 35.2g/L;
s3, separating sodium sulfate: cooling the mother solution after separating glaserite to less than 0 ℃, separating out sodium sulfate, and separating out sodium sulfate crystal slurry through liquid-solid separation; after separating out sodium sulfate crystal slurry, the concentration of sodium sulfate in the mother liquor is reduced to below 50 g/L;
and drying the sodium sulfate crystal slurry to obtain a sodium sulfate product with the purity of 86.5%.
S4, sodium sulfate reacts to generate glaserite: adding a molar amount of potassium chloride solution into the sodium sulfate separated in the step S3, and reacting at 90 ℃ to generate glaserite and sodium chloride, wherein the concentration of the potassium chloride solution is 8wt.%.
S5, separating sodium chloride: and (3) cooling the mixture of the glaserite and the sodium chloride generated in the step (S4) to-5-0 ℃, crystallizing and separating the glaserite, and evaporating and crystallizing to separate the sodium chloride. S6, converting the potassium chloride to prepare potassium sulfate: combining the glaserite separated from the sodium chloride in the step S5 with the glaserite obtained in the step S2; according to the total amount of sulfate radical in the combined glaserite, adding an equimolar potassium chloride solution to react at 35 ℃ to generate potassium sulfate and sodium chloride, wherein the concentration of the potassium chloride solution is 8wt.%.
S7, separating sodium chloride: and (3) cooling the mixture of potassium sulfate and sodium chloride generated in the step (S6) to-5-0 ℃, crystallizing and separating potassium sulfate, and evaporating and crystallizing to separate sodium chloride.
The crystal separated potassium sulfate crystal slurry is dehydrated and dried, and the purity of the obtained potassium sulfate product is about 99.4 percent.
S8, secondary lithium precipitation: and adding 10% excessive sodium carbonate into the mother solution after separating the sodium sulfate crystal slurry according to the concentration of lithium sulfate in the mother solution, heating to 92 ℃ and secondarily precipitating lithium. And returning the mother solution after secondary lithium precipitation, combining with the primary lithium precipitation mother solution, and circulating the steps S1-S8.
The precipitate obtained by secondary lithium precipitation is crude lithium carbonate, and the purity of the crude lithium carbonate is 90.4%.
The crude lithium carbonate was purified as in example 1 to obtain battery grade lithium carbonate.
The embodiments described above are some, but not all embodiments of the invention. The detailed description of the embodiments of the invention is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Claims (10)
1. The method for preparing high-purity potassium sulfate by using the lithium precipitation mother liquor is characterized by taking the primary lithium precipitation mother liquor for producing lithium carbonate by a sulfuric acid method as a raw material, and comprises the following steps of:
s1, decarburizing and evaporating: decarbonizing the primary lithium precipitation mother liquor, and then evaporating and concentrating;
s2, separating glaserite: cooling the mother solution after evaporation and concentration, and separating out glaserite;
s3, separating sodium sulfate: cooling the mother solution after separating glaserite, and separating sodium sulfate;
S4, sodium sulfate reacts to generate glaserite: adding a potassium chloride solution into the sodium sulfate separated in the step S3, and heating to react to generate glaserite and sodium chloride;
s5, separating sodium chloride: separating the glaserite and sodium chloride mixture generated in the step S4 to obtain sodium chloride and glaserite;
s6, converting the potassium chloride to prepare potassium sulfate: combining the glaserite separated from the sodium chloride in the step S5 with the glaserite obtained in the step S2; adding potassium chloride solution to react to generate potassium sulfate and sodium chloride;
S7, separating sodium chloride: and (3) separating the mixture of potassium sulfate and sodium chloride generated in the step (S6) to obtain sodium chloride and potassium sulfate respectively.
2. The method for preparing high-purity potassium sulfate from lithium precipitation mother liquor according to claim 1, wherein the lithium sulfate content in the primary lithium precipitation mother liquor is 7wt.% or less, the sodium sulfate content is 5-27wt.%, and the potassium sulfate content is 8-19wt.%.
3. The method for preparing high-purity potassium sulfate from lithium precipitation mother liquor according to claim 1 or 2, wherein in the step S1, an acid solution is added to the primary lithium precipitation mother liquor to remove carbonate; preferably, adding an acid solution to enable the pH value of the primary lithium precipitation mother solution to be 4-8; more preferably, the acid solution is a sulfuric acid solution;
Preferably, the mother solution after decarbonization is concentrated by an MVR high-efficiency evaporator, and more preferably, the concentration of lithium sulfate is more than or equal to 30g/L.
4. The method for preparing high-purity potassium sulfate by using the lithium precipitation mother liquor according to claim 1 or 2, wherein in the step S2, the mother liquor after evaporation and concentration is cooled to 25 ℃ ± 5 ℃, glaserite is separated out, and glaserite crystal slurry is separated out through liquid-solid separation.
5. The method for preparing high-purity potassium sulfate by using lithium precipitation mother liquor according to claim 1 or 2, wherein in the step S3, the mother liquor from which glaserite is separated is cooled to 0 ℃ or less, sodium sulfate is separated out, and sodium sulfate crystal slurry is separated out through liquid-solid separation.
6. The method for preparing high-purity potassium sulfate by using the lithium precipitation mother liquor according to claim 1 or 2, wherein in the step S4, an equimolar amount of potassium chloride solution is added into the sodium sulfate separated in the step S3, and glaserite and sodium chloride are generated by reaction; preferably, the mass concentration of the potassium chloride solution is 5-10%;
preferably, the reaction temperature is 80 to 100 ℃.
7. The method for preparing high-purity potassium sulfate by using lithium precipitation mother liquor according to claim 1 or 2, wherein sodium chloride is separated: in the step S5, the mixture of the glaserite and the sodium chloride generated in the step S4 is cooled to-5-0 ℃, the glaserite is separated by crystallization, and the sodium chloride is separated by evaporation and crystallization.
8. The method for preparing high-purity potassium sulfate by using the lithium precipitation mother liquor according to claim 1 or 2, wherein in the step S6, an equimolar potassium chloride solution is added according to the total amount of sulfate radicals in the combined glaserite to react to generate potassium sulfate and sodium chloride;
preferably, the mass concentration of the potassium chloride solution is 5-10%;
preferably, the reaction temperature is 25 to 50 ℃.
9. The method for preparing high-purity potassium sulfate by using the lithium precipitation mother liquor according to claim 1 or 2, wherein in the step S7, the mixture of potassium sulfate and sodium chloride generated in the step S6 is cooled to-5-0 ℃, potassium sulfate is separated by crystallization, and sodium chloride is separated by evaporation and crystallization.
10. The method for preparing high-purity potassium sulfate by using lithium precipitation mother liquor according to claim 1 or 2, wherein the purity of the potassium sulfate prepared by the method is more than 99%.
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