CN118419960A - Method for preparing aluminum fluoride by using waste liquid of lithium precipitation concentrated mother solution - Google Patents
Method for preparing aluminum fluoride by using waste liquid of lithium precipitation concentrated mother solution Download PDFInfo
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- 239000002699 waste material Substances 0.000 title claims abstract description 90
- 239000007788 liquid Substances 0.000 title claims abstract description 77
- 238000001556 precipitation Methods 0.000 title claims abstract description 73
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 62
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 62
- IRPGOXJVTQTAAN-UHFFFAOYSA-N 2,2,3,3,3-pentafluoropropanal Chemical compound FC(F)(F)C(F)(F)C=O IRPGOXJVTQTAAN-UHFFFAOYSA-N 0.000 title claims abstract description 55
- KLZUFWVZNOTSEM-UHFFFAOYSA-K Aluminum fluoride Inorganic materials F[Al](F)F KLZUFWVZNOTSEM-UHFFFAOYSA-K 0.000 title claims abstract description 53
- 238000000034 method Methods 0.000 title claims abstract description 52
- 239000010413 mother solution Substances 0.000 title abstract description 29
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 claims abstract description 150
- 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 claims abstract description 78
- 239000011734 sodium Substances 0.000 claims abstract description 78
- 229910052708 sodium Inorganic materials 0.000 claims abstract description 78
- 239000007787 solid Substances 0.000 claims abstract description 54
- 238000002309 gasification Methods 0.000 claims abstract description 44
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 43
- 238000010438 heat treatment Methods 0.000 claims abstract description 38
- 159000000000 sodium salts Chemical class 0.000 claims abstract description 32
- 238000007740 vapor deposition Methods 0.000 claims abstract description 31
- 238000002156 mixing Methods 0.000 claims abstract description 28
- ABTOQLMXBSRXSM-UHFFFAOYSA-N silicon tetrafluoride Chemical compound F[Si](F)(F)F ABTOQLMXBSRXSM-UHFFFAOYSA-N 0.000 claims abstract description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 24
- 238000001035 drying Methods 0.000 claims abstract description 18
- 238000001914 filtration Methods 0.000 claims abstract description 18
- 238000005979 thermal decomposition reaction Methods 0.000 claims abstract description 16
- 238000004064 recycling Methods 0.000 claims abstract description 9
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 54
- 239000011737 fluorine Substances 0.000 claims description 54
- 229910052731 fluorine Inorganic materials 0.000 claims description 54
- 238000006243 chemical reaction Methods 0.000 claims description 36
- 239000002351 wastewater Substances 0.000 claims description 28
- 239000010703 silicon Substances 0.000 claims description 17
- 229910052710 silicon Inorganic materials 0.000 claims description 17
- -1 sodium fluorosilicate Chemical compound 0.000 claims description 16
- 239000012452 mother liquor Substances 0.000 claims description 14
- 238000005189 flocculation Methods 0.000 claims description 13
- 230000016615 flocculation Effects 0.000 claims description 13
- 239000002253 acid Substances 0.000 claims description 12
- 238000006386 neutralization reaction Methods 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 10
- 230000035484 reaction time Effects 0.000 claims description 9
- 230000002378 acidificating effect Effects 0.000 claims description 8
- 239000008394 flocculating agent Substances 0.000 claims description 8
- 230000002596 correlated effect Effects 0.000 claims description 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 5
- 230000000630 rising effect Effects 0.000 claims description 5
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 claims description 4
- 229910000360 iron(III) sulfate Inorganic materials 0.000 claims description 4
- 239000000758 substrate Substances 0.000 claims 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 abstract description 19
- 229910052782 aluminium Inorganic materials 0.000 abstract description 19
- 238000005868 electrolysis reaction Methods 0.000 abstract description 17
- 239000007789 gas Substances 0.000 description 42
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 32
- 239000000047 product Substances 0.000 description 16
- 229910000029 sodium carbonate Inorganic materials 0.000 description 16
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 11
- 229910052808 lithium carbonate Inorganic materials 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- 230000008569 process Effects 0.000 description 8
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 7
- 238000002360 preparation method Methods 0.000 description 7
- 239000000243 solution Substances 0.000 description 7
- 239000012535 impurity Substances 0.000 description 6
- 239000002244 precipitate Substances 0.000 description 6
- 239000002994 raw material Substances 0.000 description 6
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 4
- 239000012043 crude product Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 230000009471 action Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- TXBSWQWDLFJQMU-UHFFFAOYSA-N 4-(chloromethyl)-1,2-diethoxybenzene Chemical compound CCOC1=CC=C(CCl)C=C1OCC TXBSWQWDLFJQMU-UHFFFAOYSA-N 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- 239000004115 Sodium Silicate Substances 0.000 description 2
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 2
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 2
- 239000006184 cosolvent Substances 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000010436 fluorite Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 2
- 229910052911 sodium silicate Inorganic materials 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 238000005019 vapor deposition process Methods 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 239000012267 brine Substances 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000000875 corresponding effect Effects 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 229940104869 fluorosilicate Drugs 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 239000002367 phosphate rock Substances 0.000 description 1
- OJMIONKXNSYLSR-UHFFFAOYSA-N phosphorous acid Chemical compound OP(O)O OJMIONKXNSYLSR-UHFFFAOYSA-N 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/48—Halides, with or without other cations besides aluminium
- C01F7/50—Fluorides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Removal Of Specific Substances (AREA)
Abstract
The application relates to the technical field of recycling of aluminum electrolysis waste residue resources, in particular to a method for preparing aluminum fluoride by using waste liquid of lithium precipitation concentrated mother solution; the method comprises the following steps: mixing sodium salt and waste liquid, and filtering to obtain sodium fluosilicate filter residues; drying sodium fluosilicate filter residues to obtain sodium fluosilicate with preset water content; mixing aluminum chloride solid and sodium fluosilicate with preset water content, and then performing thermal decomposition to obtain aluminum chloride gas and silicon tetrafluoride gas respectively; vapor deposition is carried out on aluminum chloride gas and silicon tetrafluoride gas to obtain aluminum fluoride products; wherein the preset water content is less than or equal to 2%; the thermal decomposition comprises a heating section, a gasification stage and a decomposition stage, wherein the end temperature of the heating section is less than or equal to 170 ℃, the gasification stage is used for gasifying aluminum chloride solids, and the decomposition stage is used for decomposing sodium fluosilicate to generate silicon tetrafluoride gas; the method can produce aluminum fluoride solids with purity of more than 97%.
Description
Technical Field
The application relates to the technical field of recycling of aluminum electrolysis waste residue resources, in particular to a method for preparing aluminum fluoride by using waste liquid of lithium precipitation concentrated mother solution.
Background
In addition to the common technology of extracting lithium from lithium ores, salt lake brine and waste lithium batteries, the process of extracting lithium carbonate from lithium-containing waste residues generated in the electrolytic aluminum industry is also a research hot spot of the current lithium extraction process. The process of extracting lithium carbonate from the aluminum electrolysis waste residue at the present stage is basically to firstly convert fluoride in the aluminum electrolysis waste residue and prepare a spinelle or aluminum fluoride product so as to remove impurities from the aluminum electrolysis waste residue, and then use a precipitation method to prepare the lithium carbonate from the lithium precipitation concentrated mother solution generated after the impurities are removed. After the lithium carbonate is prepared by the precipitation method, the lithium carbonate solid is required to be collected by a filtering mode, and the filtered waste liquid contains elements such as fluorine, aluminum, silicon and the like, so that the recovery value is high, but the treatment technology for the waste liquid is almost blank. In addition, the aluminum fluoride produced by fluoride in the aluminum electrolysis waste residues can be theoretically used as a cosolvent in the aluminum electrolysis production process, so that the quality of an aluminum electrolysis product can be improved, energy conservation and emission reduction in the aluminum electrolysis production process can be realized, but the purity of the aluminum fluoride produced by fluoride in the aluminum electrolysis waste residues is lower, and the application of the aluminum fluoride as the cosolvent in the aluminum electrolysis production process can be influenced; although high-purity aluminum fluoride is mostly used in the aluminum electrolysis process at present, the high-purity aluminum fluoride mainly uses fluorite and phosphorite as raw materials, and the fluorite in the raw materials is a non-renewable resource, which limits the large-scale development of the aluminum fluoride process to a certain extent.
Although the aluminum fluoride can be prepared by using the waste liquid of the lithium precipitation concentrated mother solution as the raw material in theory to solve the problem of treatment of the waste liquid of the lithium precipitation concentrated mother solution, the purity of the aluminum fluoride product prepared by using the waste liquid of the lithium precipitation concentrated mother solution as the raw material is lower, and the problem of large-scale preparation of high-purity aluminum fluoride still cannot be solved.
The existing industrial aluminum fluoride preparation process is divided into two major types, namely a hydrofluoric acid method and a fluosilicic acid method, and the aluminum fluoride preparation technology comprises the following steps: (1) The method for preparing aluminum fluoride by recycling fluorine-containing waste comprises the following steps: grinding fluorine-containing waste, carrying out blending reaction with concentrated sulfuric acid, collecting gas generated by the blending reaction at a high temperature, cooling and depressurizing the generated gas to obtain liquid hydrogen fluoride, rectifying the liquid hydrogen fluoride to obtain anhydrous hydrogen fluoride, gasifying the anhydrous hydrogen fluoride to heat, and then reacting the heated hydrogen fluoride with aluminum hydroxide to generate aluminum fluoride; (2) The production method for producing aluminum fluoride by using fluosilicic acid as a raw material comprises the following steps: adding a certain amount of aluminum hydroxide into fluosilicic acid solution to obtain aluminum fluoride solution, controlling the pH value of the aluminum fluoride solution to be 1.2-2, filtering the aluminum fluoride solution, adding a crystallization aid to crystallize to obtain suspension of aluminum fluoride trihydrate, filtering out the aluminum fluoride trihydrate of the suspension, and finally drying and calcining to obtain anhydrous aluminum fluoride; (3) a process for producing a high-purity fluoride comprising the steps of: first, the fluorosilicate is pyrolyzed, and then the high-purity aluminum fluoride is prepared through sectional temperature control and fluidized vapor deposition.
Disclosure of Invention
The application provides a method for preparing aluminum fluoride by using waste liquid of lithium precipitation concentrated mother solution, which aims to solve the following technical problems: how to prepare the aluminum fluoride product with higher purity while recovering the waste liquid resource of the lithium precipitation concentrated mother solution.
In a first aspect, the present application provides a method for preparing aluminum fluoride using a waste liquid of a lithium precipitation concentrated mother liquor, wherein the waste liquid of the lithium precipitation concentrated mother liquor contains fluorine and silicon, and the method comprises:
Mixing sodium salt with the waste liquid, carrying out precipitation reaction on fluorine and silicon in the waste liquid and the sodium salt, and then filtering to obtain sodium fluosilicate filter residues;
drying the sodium fluosilicate filter residues to obtain sodium fluosilicate with preset water content;
Mixing aluminum chloride solid and the sodium fluosilicate with preset water content, and then performing thermal decomposition to obtain aluminum chloride gas and silicon tetrafluoride gas respectively;
Vapor deposition is carried out on the aluminum chloride gas and the silicon tetrafluoride gas to obtain an aluminum fluoride product;
wherein the preset water content is less than or equal to 2%;
The thermal decomposition comprises a heating section, a gasification stage and a decomposition stage, wherein the end temperature of the heating section is less than or equal to 170 ℃, the gasification stage is used for gasifying the aluminum chloride solid, and the decomposition stage is used for decomposing the sodium fluosilicate to generate silicon tetrafluoride gas.
Optionally, the initial temperature of the gasification stage is more than or equal to 170 ℃, the end temperature of the gasification stage is less than or equal to 400 ℃, and the heating rate of the gasification stage is 8 ℃/min-23 ℃/min;
The initial temperature of the decomposition stage is more than or equal to 400 ℃, the end temperature of the decomposition stage is 500-600 ℃, and the temperature rising rate of the decomposition stage is 3-17 ℃/min.
Optionally, the gasification stage and the decomposition stage are respectively 10 min-30 min.
Optionally, the actual addition amount of the aluminum chloride solid is 1.0-1.8 times of the theoretical addition amount of the aluminum chloride solid, and the theoretical addition amount of the aluminum chloride solid is positively correlated with the fluorine content of the sodium fluosilicate.
Optionally, the molar ratio of the sodium element in the sodium salt to the fluorine element in the waste liquid is 1:0.5-3.
Optionally, the time of the precipitation reaction is 0.5-2.0 h.
Optionally, the temperature of the vapor deposition is 200-400 ℃, and the time of the vapor deposition is 10-15 min.
Optionally, the drying the sodium fluosilicate filter residues to obtain sodium fluosilicate comprises the following steps:
Mixing a flocculating agent with the sodium fluosilicate filter residues, performing flocculation reaction on the flocculating agent and the sodium fluosilicate filter residues, and drying to obtain sodium fluosilicate;
Wherein the flocculation reaction time is 5 min-10 min.
Optionally, the flocculant comprises polyaluminum chloride and/or polymeric ferric sulfate.
Optionally, the method further comprises:
Mixing sodium salt with the waste liquid, carrying out precipitation reaction on fluorine and silicon in the waste liquid and the sodium salt, and then filtering to obtain sodium fluosilicate filter residues and fluorine-containing acidic waste water;
Mixing an alkaline substance with the fluorine-containing acid wastewater to perform a neutralization reaction on the alkaline substance and the fluorine-containing acid wastewater, and filtering to obtain acid-removing wastewater;
Wherein the acid-removing wastewater is used as the waste liquid for recycling.
Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:
The embodiment of the application provides a method for preparing aluminum fluoride by using waste liquid of lithium precipitation concentrated mother liquor, wherein the waste liquid of the lithium precipitation concentrated mother liquor contains fluorine and silicon, and the method comprises the following steps: mixing sodium salt with the waste liquid, carrying out precipitation reaction on fluorine and silicon in the waste liquid and the sodium salt, and then filtering to obtain sodium fluosilicate filter residues; drying the sodium fluosilicate filter residues to obtain sodium fluosilicate with preset water content; mixing aluminum chloride solid and the sodium fluosilicate with preset water content, and then performing thermal decomposition to obtain aluminum chloride gas and silicon tetrafluoride gas respectively; vapor deposition is carried out on the aluminum chloride gas and the silicon tetrafluoride gas to obtain an aluminum fluoride product; wherein the preset water content is less than or equal to 2%; the thermal decomposition comprises a heating section, a gasification stage and a decomposition stage, wherein the end temperature of the heating section is less than or equal to 170 ℃, the gasification stage is used for gasifying the aluminum chloride solid, and the decomposition stage is used for decomposing the sodium fluosilicate to generate silicon tetrafluoride gas. Sodium of sodium salt and fluorine and silicon in the waste liquid of the lithium precipitation concentration mother liquor are subjected to precipitation reaction to generate sodium fluosilicate precipitate, the generated sodium fluosilicate precipitate is filtered and flocculated and dried, moisture in the sodium fluosilicate precipitate can be removed, and accordingly sodium fluosilicate with moisture content less than or equal to 2% can be obtained, sodium fluosilicate with moisture content less than or equal to 2% can be thermally decomposed together with aluminum chloride solid, aluminum oxide impurities generated by reaction of the moisture of sodium silicate and the aluminum chloride solid can be prevented, the generated aluminum oxide impurities can influence the purity of aluminum chloride gas and silicon tetrafluoride gas obtained by thermal decomposition, and accordingly pure aluminum chloride gas and pure silicon tetrafluoride gas can be respectively obtained.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.
In order to more clearly illustrate the embodiments of the application or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort.
FIG. 1 is a schematic flow chart of a method for preparing aluminum fluoride by using waste liquid of lithium precipitation concentrated mother liquor according to an embodiment of the application;
Fig. 2 is a detailed flow chart of a method for preparing aluminum fluoride by using a waste liquid of a lithium precipitation concentrated mother solution according to an embodiment of the application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
Various embodiments of the application may exist in a range of forms; it should be understood that the description in a range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the application; accordingly, it should be considered that the description of the range has specifically disclosed all possible subranges and a single numerical value within that range; for example, it should be considered that a description of a range from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the stated range, such as 1, 2, 3, 4, 5, and 6, wherever the range applies; in addition, whenever a numerical range is referred to herein, it is meant to include any reference number (fractional or integer) within the indicated range.
Herein, the terms "comprising," including, "and the like mean" including but not limited to. Relational terms such as "first" and "second", and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. "and/or", describes an association relationship of an association object, and indicates that there may be three relationships, for example, a and/or B, and may indicate: a alone, a and B together, B alone; wherein A, B may be singular or plural. "at least one" means one or more, "a plurality" means two or more; "at least one", "at least one of" or the like refer to any combination of these items, including any combination of single item(s) or plural items(s); for example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively. Unless otherwise specifically indicated, the various raw materials, reagents, instruments, equipment and the like used in the present application are commercially available or may be prepared by existing methods.
It should be noted that, with respect to the prior arts (1), (2) and (3) described in the background art, the inventors found that these techniques either obtained aluminum fluoride products with low purity or the energy consumption cost of the preparation process was high, and the fluorine-containing acidic waste liquid generated in the preparation process was not properly treated.
FIG. 1 schematically shows a process flow diagram of a method for preparing aluminum fluoride using a waste liquid of a lithium precipitation concentrated mother liquor according to an embodiment of the present application;
As shown in fig. 1, the method for preparing aluminum fluoride by using a waste liquid of a lithium precipitation concentrated mother solution, wherein the waste liquid of the lithium precipitation concentrated mother solution contains fluorine and silicon, comprises the following steps:
s1, mixing sodium salt and the waste liquid, enabling fluorine and silicon in the waste liquid to perform precipitation reaction with the sodium salt, and then filtering to obtain sodium fluosilicate filter residues;
s2, drying the sodium fluosilicate filter residues to obtain sodium fluosilicate with preset water content;
s3, mixing aluminum chloride solids with the sodium fluosilicate with the preset water content, and then performing thermal decomposition to obtain aluminum chloride gas and silicon tetrafluoride gas respectively;
s4, carrying out vapor deposition on the aluminum chloride gas and the silicon tetrafluoride gas to obtain an aluminum fluoride product;
wherein the preset water content is less than or equal to 2%;
The thermal decomposition comprises a heating section, a gasification stage and a decomposition stage, wherein the end temperature of the heating section is less than or equal to 170 ℃, the gasification stage is used for gasifying the aluminum chloride solid, and the decomposition stage is used for decomposing the sodium fluosilicate to generate silicon tetrafluoride gas.
It should be noted that the thermal decomposition and vapor deposition may be performed in the same apparatus, and the generated aluminum chloride gas and silicon tetrafluoride gas may be caused to react directly, thereby obtaining a pure aluminum fluoride product.
The preparation method of the waste liquid of the lithium precipitation concentrated mother solution is as follows:
mixing the lithium precipitation concentrated mother solution and sodium carbonate, carrying out a lithium precipitation reaction on lithium in the lithium precipitation concentrated mother solution and carbonate of the sodium carbonate, and filtering to obtain waste liquid of the lithium precipitation concentrated mother solution and a crude product of the lithium carbonate;
washing and drying the lithium carbonate crude product to obtain a lithium carbonate product; the actual adding amount of the sodium carbonate can be 1.1-2 times of the theoretical adding amount of the sodium carbonate, and the theoretical adding amount of the sodium carbonate is calculated according to the content of lithium in the precipitated lithium concentrated mother solution.
The time of the lithium precipitation reaction is 1.0h to 2.5h.
The source of the aluminum electrolysis waste residue of the lithium precipitation concentrated mother solution can be overhaul residue, waste cathode and electrolyte.
In some alternative embodiments, the initial temperature of the heating stage is 20 ℃ to 30 ℃, the final temperature of the heating stage is less than or equal to 170 ℃, and the heating rate of the heating stage is 11 ℃/min to 17 ℃/min;
The initial temperature of the gasification stage is more than or equal to 170 ℃, the end temperature of the gasification stage is less than or equal to 400 ℃, and the heating rate of the gasification stage is 8-23 ℃/min;
The initial temperature of the decomposition stage is more than or equal to 400 ℃, the end temperature of the decomposition stage is 500-600 ℃, and the temperature rising rate of the decomposition stage is 3-17 ℃/min;
In these embodiments, the initial temperature of the heating stage may be 20 ℃ to 30 ℃, and the end temperature of the heating stage may be less than or equal to 170 ℃, and the heating rate of the heating stage may be 11 ℃/min to 17 ℃/min, sufficient heat may be provided to cause the aluminum chloride solids and sodium fluorosilicate to rapidly heat up to 170 ℃, thereby facilitating the subsequent gasification stage; the initial temperature of the gasification stage can be more than or equal to 170 ℃, the end temperature of the gasification stage can be less than or equal to 400 ℃, and the heating rate of the gasification stage can be 8 ℃/min-23 ℃/min, so that aluminum chloride solid can be promoted to be sufficiently heated to form aluminum chloride gas, and the subsequent vapor deposition of the aluminum chloride gas and silicon tetrafluoride gas can be facilitated to obtain a pure aluminum fluoride product.
The initial temperature of the heating stage may be 20 ℃, 25 ℃ or 30 ℃.
The heating stage may have a heating rate of 11, 12, 13, 14, 15, 16, 17 or 18 deg.c/min.
The temperature rise rate of the gasification stage may be 8℃/min、9℃/min、10℃/min、11℃/min、12℃/min、13℃/min、14℃/min、15℃/min、16℃/min、17℃/min、18℃/min、19℃/min、20℃/min、21℃/min、22℃/min or 23 deg.c/min.
The end temperature of the decomposition stage may be 500 ℃, 510 ℃, 520 ℃, 530 ℃, 540 ℃, 550 ℃, 560 ℃, 570 ℃, 580 ℃, 590 ℃ or 600 ℃.
The temperature rise rate of the decomposition stage may be 3℃/min、4℃/min、5℃/min、6℃/min、7℃/min、8℃/min、9℃/min、10℃/min、11℃/min、12℃/min、13℃/min、14℃/min、15℃/min、16℃/min or 17 deg.c/min.
In some alternative embodiments, the heating stage is between 10min and 15min, and the gasification stage and the decomposition stage are each between 10min and 30min;
In these embodiments, the heating stage may be for 10min to 15min, and sufficient heat may be further provided to promote rapid heating of the aluminum chloride solids and sodium fluorosilicate to 170 ℃, which may facilitate the subsequent gasification stage; in addition, the time of the gasification stage and the decomposition stage can be respectively 10 min-30 min, so that aluminum chloride solid can be fully converted into aluminum chloride gas and sodium fluosilicate can be decomposed to generate silicon tetrafluoride gas, and a pure aluminum fluoride product can be generated between the aluminum chloride gas and the silicon tetrafluoride gas in the vapor deposition process.
The heating stage may be for 10min, 11min, 12min, 13min, 14min or 15min.
The gasification stage and the decomposition stage may be for 10min, 15min, 20min, 25min or 30min, respectively.
In some alternative embodiments, the actual addition of aluminum chloride solids is 1.0 to 1.8 times the theoretical addition of aluminum chloride solids, which is positively correlated to the fluorine content of the sodium fluorosilicate;
In these embodiments, the actual amount of aluminum chloride solids added may be 1.0 to 1.8 times the theoretical amount of aluminum chloride solids added, and the theoretical amount of aluminum chloride solids added may be positively correlated with the fluorine content of the sodium fluorosilicate, and a sufficient amount of aluminum chloride solids may be provided during the gasification stage, and a sufficient amount of aluminum chloride solids may be formed through the gasification stage to form a sufficient amount of aluminum chloride gas.
The actual amount of aluminum chloride solids added may be 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, or 1.8 of the theoretical amount of aluminum chloride solids added.
In some alternative embodiments, the molar ratio of the sodium element in the sodium salt to the fluorine element in the waste liquid is 1:0.5-3;
in these embodiments, the molar ratio of the sodium element in the sodium salt to the fluorine element in the waste liquid may be 1:0.5-3, and the sodium in the sodium salt and the fluorine in the waste liquid may be promoted to react sufficiently, so that a sufficient amount of sodium fluorosilicate filter residue may be obtained.
The molar ratio of the sodium element in the sodium salt to the fluorine element in the waste liquid can be 1:0.5, 1:1.5, 1:2.0, 1:2.5 or 1:3.0.
In some alternative embodiments, the precipitation reaction time is from 0.5h to 2.0h;
In these embodiments, the precipitation reaction time may be 0.5h to 2.0h, and fluorine and silicon in the waste liquid of the lithium precipitation concentration mother liquor may be caused to sufficiently react with sodium of sodium salt, so that a sufficient amount of sodium fluorosilicate filter residue may be obtained.
In some alternative embodiments, the vapor deposition temperature is 200 ℃ to 400 ℃ and the vapor deposition time is 10min to 15min;
In these embodiments, the vapor deposition temperature may be 200 ℃ to 400 ℃ and the vapor deposition time may be 10min to 15min, which may promote a sufficient reaction between the aluminum chloride gas and the silicon tetrafluoride gas, thereby allowing a pure aluminum fluoride product to be obtained.
The vapor deposition temperature may be 200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃, 300 ℃, 310 ℃, 320 ℃, 330 ℃, 340 ℃, 350 ℃, 360 ℃, 370 ℃, 380 ℃, 390 ℃, or 400 ℃.
The vapor deposition time may be 10min, 11min, 12min, 13min, 14min, or 15min.
FIG. 2 schematically shows a detailed flow chart of a method for preparing aluminum fluoride by using waste liquid of lithium precipitation concentrated mother liquor according to an embodiment of the present application;
In some alternative embodiments, as shown in fig. 2, the drying the sodium fluorosilicate filter residue to obtain sodium fluorosilicate includes the steps of:
s201, mixing a flocculating agent and the sodium fluosilicate filter residues, performing flocculation reaction on the flocculating agent and the sodium fluosilicate filter residues, and drying to obtain sodium fluosilicate;
Wherein the flocculation reaction time is 5-10 min;
In these embodiments, the sodium fluorosilicate filter residue is subjected to flocculation reaction using a flocculant before drying, and the flocculant can be used to sufficiently absorb moisture of the sodium fluorosilicate filter residue, so that sodium fluorosilicate having a predetermined water content of 2% or less can be obtained.
In some alternative embodiments, the flocculant comprises polyaluminum chloride and/or polymeric ferric sulfate.
In these embodiments, the flocculant may comprise polyaluminum chloride and/or polymeric ferric sulfate, which may promote sufficient reaction of the water of the sodium fluorosilicate filter residue with the flocculant, thereby allowing a sodium fluorosilicate having a water content of 2% or less to be obtained.
In some alternative embodiments, the method further comprises:
S101, mixing sodium salt with the waste liquid, carrying out precipitation reaction on fluorine and silicon in the waste liquid and the sodium salt, and then filtering to obtain sodium fluosilicate filter residue and fluorine-containing acidic waste water;
S102, mixing an alkaline substance with the fluorine-containing acid wastewater to perform a neutralization reaction on the alkaline substance and the fluorine-containing acid wastewater, and filtering to obtain acid-removing wastewater;
wherein the acid-removing wastewater is used as the waste liquid for recycling;
In these embodiments, the method may further comprise mixing the alkaline material with the fluorine-containing acidic wastewater, wherein a neutralization reaction may occur between the alkaline material and the acidic component of the fluorine-containing acidic wastewater, and a neutral acid-removal wastewater may be obtained, and the acid-removal wastewater may be recycled as a waste liquid, thereby realizing recycling of wastewater resources.
The alkaline substance may be sodium hydroxide.
The terminal pH of the neutralization reaction may be 7 to 8.
The application will be further illustrated with reference to specific examples. The experimental methods in the following examples, for which specific conditions are not noted, are generally determined according to industry standards; if there is no corresponding industry standard, it is carried out according to the general international standard, the conventional conditions, or according to the conditions recommended by the manufacturer.
Example 1
As shown in fig. 2, a method for preparing aluminum fluoride by using a waste liquid of a lithium precipitation concentrated mother liquor, wherein the waste liquid of the lithium precipitation concentrated mother liquor contains fluorine and silicon, comprises the following steps:
S101, mixing sodium salt and waste liquid, carrying out precipitation reaction on fluorine and silicon in the waste liquid and the sodium salt, and then filtering to obtain sodium fluosilicate filter residue and fluorine-containing acidic waste water;
S102, mixing an alkaline substance and fluorine-containing acid wastewater, enabling the alkaline substance and the fluorine-containing acid wastewater to undergo a neutralization reaction, and filtering to obtain acid-removing wastewater; recycling acid-removing wastewater as waste liquid; the pH value at the end point of the neutralization reaction is 7.21;
S201, mixing a flocculating agent and sodium fluosilicate filter residues, performing flocculation reaction on the flocculating agent and the sodium fluosilicate filter residues, and drying to obtain sodium fluosilicate; the flocculation reaction time is 5min, and the flocculant is polyaluminum chloride;
S3, mixing aluminum chloride solid and sodium fluosilicate with preset water content, and then performing thermal decomposition to obtain aluminum chloride gas and silicon tetrafluoride gas respectively;
S4, carrying out vapor deposition on aluminum chloride gas and silicon tetrafluoride gas to obtain an aluminum fluoride product;
Wherein the preset water content is less than or equal to 2%;
the thermal decomposition comprises a heating section, a gasification stage and a decomposition stage, wherein the end temperature of the heating section is 170 ℃, the gasification stage is used for gasifying aluminum chloride solids, and the decomposition stage is used for decomposing sodium fluosilicate to generate silicon tetrafluoride gas.
The preparation method of the waste liquid of the lithium precipitation concentrated mother solution comprises the following steps:
mixing the lithium precipitation concentrated mother solution and sodium carbonate, carrying out a lithium precipitation reaction on lithium in the lithium precipitation concentrated mother solution and carbonate of the sodium carbonate, and filtering to obtain waste liquid of the lithium precipitation concentrated mother solution and a crude product of the lithium carbonate;
washing and drying the lithium carbonate crude product to obtain a lithium carbonate product; the actual adding amount of the sodium carbonate can be 1.1 times of the theoretical adding amount of the sodium carbonate, and the theoretical adding amount of the sodium carbonate is calculated according to the content of lithium in the precipitated lithium concentrated mother solution.
The time of the lithium precipitation reaction is 1.0h.
The source of the aluminum electrolysis waste residue of the lithium precipitation concentrated mother solution is overhaul residue.
The initial temperature of the gasification stage is 170 ℃, the end temperature of the gasification stage is 400 ℃, and the heating rate of the gasification stage is 11.5 ℃/min;
The initial temperature of the decomposition stage was 400 ℃, the end temperature of the decomposition stage was 550 ℃, and the temperature rise rate of the decomposition stage was 7.5 ℃/min.
The gasification stage and the decomposition stage were each carried out for 20min.
The actual addition amount of the aluminum chloride solid is 1.0 times of the theoretical addition amount of the aluminum chloride solid, and the theoretical addition amount of the aluminum chloride solid is positively correlated with the fluorine content of the sodium fluosilicate.
The molar ratio of the sodium element in the sodium salt to the fluorine element in the waste liquid is 1:0.5.
The time for the precipitation reaction was 0.5h.
The temperature of vapor deposition was 250℃and the time of vapor deposition was 10min.
Example 2
Based on the disclosure of example 1, the following operations were further performed:
the flocculation reaction time was 5min.
The actual amount of sodium carbonate added may be 1.4 times the theoretical amount of sodium carbonate added.
The time of the lithium precipitation reaction is 1.5h.
The source of the aluminum electrolysis waste residue of the lithium precipitation concentrated mother solution is a waste cathode.
The pH at the end of the neutralization reaction was 7.38.
The end temperature of the decomposition stage was 500 ℃.
The gasification stage and the decomposition stage were each 10min.
The actual addition of aluminum chloride solids was 1.4 times the theoretical addition of aluminum chloride solids.
The molar ratio of the sodium element in the sodium salt to the fluorine element in the waste liquid is 1:1.
The time of the precipitation reaction was 1.0h.
The temperature of vapor deposition was 200℃and the time of vapor deposition was 15min.
Example 3
Based on the disclosure of example 1, the following operations were further performed:
The flocculation reaction time was 10min.
The actual amount of sodium carbonate added may be 2.0 times the theoretical amount of sodium carbonate added.
The time of the lithium precipitation reaction is 2.5h.
The source of the aluminum electrolysis waste residue of the lithium precipitation concentrated mother solution is overhaul residue.
The pH at the end of the neutralization reaction was 7.45.
The end temperature of the decomposition stage was 600 ℃.
The gasification stage and the decomposition stage were each carried out for 30min.
The actual addition of aluminum chloride solids was 1.8 times the theoretical addition of aluminum chloride solids.
The molar ratio of the sodium element in the sodium salt to the fluorine element in the waste liquid is 1:2.
The time of the precipitation reaction was 1.5h.
The temperature of vapor deposition was 350℃and the time of vapor deposition was 10min.
Example 4
Based on the disclosure of example 1, the following operations were further performed:
The flocculation reaction time was 10min.
The actual amount of sodium carbonate added may be 1.8 times the theoretical amount of sodium carbonate added.
The time of the lithium precipitation reaction is 2.0h.
The source of the aluminum electrolysis waste residue of the lithium precipitation concentrated mother solution is electrolyte.
The pH at the end of the neutralization reaction was 7.83.
The actual addition of aluminum chloride solids was 1.5 times the theoretical addition of aluminum chloride solids.
The molar ratio of the sodium element in the sodium salt to the fluorine element in the waste liquid is 1:2.
The time of the precipitation reaction was 1.5h.
The temperature of vapor deposition was 400℃and the time of vapor deposition was 5min.
Comparative example 1
Based on the disclosure of example 1, the following operations were further performed:
the temperature rising rate in the gasification stage is 46 ℃/min;
The end temperature of the decomposition stage was 550℃and the temperature rise rate of the decomposition stage was 30℃per minute.
The gasification stage and the decomposition stage were each 5min.
Comparative example 2
Based on the disclosure of example 1, the following operations were further performed:
The temperature rising rate of the gasification stage is 5.75 ℃/min;
The end temperature of the decomposition stage was 500℃and the temperature rise rate of the decomposition stage was 2.5℃per minute.
The gasification stage and the decomposition stage were each 40min.
Comparative example 3
Based on the disclosure of example 1, the following operations were further performed:
The actual addition amount of the aluminum chloride solid is 0.5 times of the theoretical addition amount of the aluminum chloride solid, and the theoretical addition amount of the aluminum chloride solid is positively correlated with the fluorine content of the sodium fluosilicate.
Comparative example 4
Based on the disclosure of example 1, the following operations were further performed:
The actual addition amount of the aluminum chloride solid is 2.0 times of the theoretical addition amount of the aluminum chloride solid, and the theoretical addition amount of the aluminum chloride solid is positively correlated with the fluorine content of the sodium fluosilicate.
Comparative example 5
Based on the disclosure of example 1, the following operations were further performed:
the molar ratio of the sodium element in the sodium salt to the fluorine element in the waste liquid is 1:0.2.
The time of the precipitation reaction was 0.2h.
Comparative example 6
Based on the disclosure of example 1, the following operations were further performed:
The molar ratio of the sodium element in the sodium salt to the fluorine element in the waste liquid is 1:5.
The time of the precipitation reaction was 3.0h.
Comparative example 7
Based on the disclosure of example 1, the following operations were further performed:
the temperature of vapor deposition was 100deg.C and the time of vapor deposition was 5min.
Comparative example 8
Based on the disclosure of example 1, the following operations were further performed:
The temperature of vapor deposition was 600℃and the time of vapor deposition was 20min.
Related experiment and effect data:
the aluminum fluoride products obtained in each of the examples and comparative examples were each tested for purity using the standard of GB-T4292-2017, and the results are shown in Table 1.
Table 1 table of purity of aluminum fluoride obtained in each example and comparative example
As can be seen from Table 1, according to the method for preparing aluminum fluoride by using the waste liquid of the lithium precipitation concentrated mother liquid provided by the embodiment of the application, sodium of sodium salt and fluorine and silicon in the waste liquid of the lithium precipitation concentrated mother liquid are subjected to precipitation reaction to generate sodium fluosilicate precipitate, the generated sodium fluosilicate precipitate is filtered and flocculated and dried, water in the sodium fluosilicate precipitate can be removed, so that sodium fluosilicate with water content less than or equal to 2% can be obtained, sodium fluosilicate with water content less than or equal to 2% can be thermally decomposed together with aluminum chloride solid, the water content of sodium silicate and aluminum chloride solid can be prevented from reacting to generate aluminum oxide impurities, the generated aluminum oxide impurities can influence the purity of aluminum chloride gas and silicon tetrafluoride gas obtained by thermal decomposition, and thus pure aluminum chloride gas and pure silicon tetrafluoride gas can be respectively obtained.
Meanwhile, according to the method for preparing aluminum fluoride by using the waste liquid of the lithium precipitation concentrated mother liquid, provided by the embodiment of the application, alkaline substances can be used for reacting with fluorine-containing acid waste water to generate acid-removal waste water, and the generated acid-removal waste water can be returned to the waste liquid of the previous stage for recycling.
In addition, according to the method for preparing aluminum fluoride by using the waste liquid of the lithium precipitation concentrated mother liquor, the flocculant is used for carrying out flocculation reaction on sodium fluosilicate filter residues before drying, so that the moisture of the sodium fluosilicate filter residues can be primarily reduced, the heat consumption in the drying process can be reduced, and the heat consumption of the whole method can be reduced.
In addition, according to the method for preparing aluminum fluoride by using the waste liquid of the lithium precipitation concentrated mother solution, provided by the embodiment of the application, aluminum chloride solids are added into the thermal decomposition process in advance, and the aluminum chloride solids can be promoted to be gasified by utilizing the heat of the heating stage of the sodium fluosilicate decomposition process, so that the heat required by independently gasifying the aluminum chloride solids can be reduced, and the energy consumption of the vapor deposition process can be further reduced.
The foregoing is only a specific embodiment of the application to enable those skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A method for preparing aluminum fluoride by using waste liquid of lithium precipitation concentrated mother liquor, wherein the waste liquid of the lithium precipitation concentrated mother liquor contains fluorine and silicon, and the method is characterized by comprising the following steps:
Mixing sodium salt with the waste liquid, carrying out precipitation reaction on fluorine and silicon in the waste liquid and the sodium salt, and then filtering to obtain sodium fluosilicate filter residues;
drying the sodium fluosilicate filter residues to obtain sodium fluosilicate with preset water content;
Mixing aluminum chloride solid and the sodium fluosilicate with preset water content, and then performing thermal decomposition to obtain aluminum chloride gas and silicon tetrafluoride gas respectively;
Vapor deposition is carried out on the aluminum chloride gas and the silicon tetrafluoride gas to obtain an aluminum fluoride product;
wherein the preset water content is less than or equal to 2%;
The thermal decomposition comprises a heating section, a gasification stage and a decomposition stage, wherein the end temperature of the heating section is less than or equal to 170 ℃, the gasification stage is used for gasifying the aluminum chloride solid, and the decomposition stage is used for decomposing the sodium fluosilicate to generate silicon tetrafluoride gas.
2. The method of claim 1, wherein the step of determining the position of the substrate comprises,
The initial temperature of the heating stage is 20-30 ℃, the end temperature of the heating stage is less than or equal to 170 ℃, and the heating rate of the heating stage is 11-17 ℃/min;
The initial temperature of the gasification stage is more than or equal to 170 ℃, the end temperature of the gasification stage is less than or equal to 400 ℃, and the heating rate of the gasification stage is 8-23 ℃/min;
The initial temperature of the decomposition stage is more than or equal to 400 ℃, the end temperature of the decomposition stage is 500-600 ℃, and the temperature rising rate of the decomposition stage is 3-17 ℃/min.
3. The method according to claim 2, wherein the heating stage is carried out for a period of 10min to 15min, and the gasification stage and the decomposition stage are carried out for a period of 10min to 30min, respectively.
4. The method according to claim 1, wherein the actual addition of aluminum chloride solids is 1.0 to 1.8 times the theoretical addition of aluminum chloride solids, which is positively correlated to the fluorine content of sodium fluorosilicate.
5. The method according to claim 1, wherein the molar ratio of sodium element in the sodium salt to fluorine element in the waste liquid is 1:0.5-3.
6. The method according to claim 1, wherein the time of the precipitation reaction is 0.5h to 2.0h.
7. The method according to claim 1, wherein the temperature of the vapor deposition is 200 ℃ to 400 ℃ and the time of the vapor deposition is 10min to 15min.
8. The method according to claim 1, wherein said drying of said sodium fluorosilicate filter residue to obtain sodium fluorosilicate comprises the steps of:
Mixing a flocculating agent with the sodium fluosilicate filter residues, performing flocculation reaction on the flocculating agent and the sodium fluosilicate filter residues, and drying to obtain sodium fluosilicate;
Wherein the flocculation reaction time is 5 min-10 min.
9. The method of claim 8, wherein the flocculant comprises polyaluminum chloride and/or polymeric ferric sulfate.
10. The method according to claim 1, wherein the method further comprises:
Mixing sodium salt with the waste liquid, carrying out precipitation reaction on fluorine and silicon in the waste liquid and the sodium salt, and then filtering to obtain sodium fluosilicate filter residues and fluorine-containing acidic waste water;
Mixing an alkaline substance with the fluorine-containing acid wastewater to perform a neutralization reaction on the alkaline substance and the fluorine-containing acid wastewater, and filtering to obtain acid-removing wastewater;
Wherein the acid-removing wastewater is used as the waste liquid for recycling.
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