CN114112783B - Method for detecting lithium content in lithium phosphate - Google Patents
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- CN114112783B CN114112783B CN202111425956.2A CN202111425956A CN114112783B CN 114112783 B CN114112783 B CN 114112783B CN 202111425956 A CN202111425956 A CN 202111425956A CN 114112783 B CN114112783 B CN 114112783B
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- 229910001386 lithium phosphate Inorganic materials 0.000 title claims abstract description 81
- TWQULNDIKKJZPH-UHFFFAOYSA-K trilithium;phosphate Chemical compound [Li+].[Li+].[Li+].[O-]P([O-])([O-])=O TWQULNDIKKJZPH-UHFFFAOYSA-K 0.000 title claims abstract description 81
- 238000000034 method Methods 0.000 title claims abstract description 37
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 35
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 35
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 claims abstract description 58
- 238000001514 detection method Methods 0.000 claims abstract description 16
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 48
- 239000000523 sample Substances 0.000 claims description 41
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 33
- 239000000706 filtrate Substances 0.000 claims description 25
- 229910001961 silver nitrate Inorganic materials 0.000 claims description 24
- 238000001354 calcination Methods 0.000 claims description 23
- 239000002244 precipitate Substances 0.000 claims description 19
- 239000012488 sample solution Substances 0.000 claims description 18
- 229910052709 silver Inorganic materials 0.000 claims description 18
- 239000004332 silver Substances 0.000 claims description 18
- -1 silver ions Chemical class 0.000 claims description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- FJOLTQXXWSRAIX-UHFFFAOYSA-K silver phosphate Chemical compound [Ag+].[Ag+].[Ag+].[O-]P([O-])([O-])=O FJOLTQXXWSRAIX-UHFFFAOYSA-K 0.000 claims description 11
- 229940019931 silver phosphate Drugs 0.000 claims description 11
- 229910000161 silver phosphate Inorganic materials 0.000 claims description 11
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 10
- 239000000047 product Substances 0.000 claims description 10
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 9
- 229910017604 nitric acid Inorganic materials 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 8
- 239000007787 solid Substances 0.000 claims description 6
- 238000001556 precipitation Methods 0.000 claims description 5
- 239000007788 liquid Substances 0.000 claims description 4
- 230000001105 regulatory effect Effects 0.000 claims description 4
- 238000000926 separation method Methods 0.000 claims description 4
- 238000012360 testing method Methods 0.000 abstract description 30
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 14
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 7
- 239000000126 substance Substances 0.000 abstract description 5
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 abstract description 3
- 229910052698 phosphorus Inorganic materials 0.000 abstract description 3
- 239000011574 phosphorus Substances 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 25
- 239000011259 mixed solution Substances 0.000 description 10
- 238000005303 weighing Methods 0.000 description 8
- 229910019142 PO4 Inorganic materials 0.000 description 5
- 238000001914 filtration Methods 0.000 description 5
- 239000010452 phosphate Substances 0.000 description 5
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000008367 deionised water Substances 0.000 description 4
- 229910021641 deionized water Inorganic materials 0.000 description 4
- 238000009413 insulation Methods 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- YPJKMVATUPSWOH-UHFFFAOYSA-N nitrooxidanyl Chemical compound [O][N+]([O-])=O YPJKMVATUPSWOH-UHFFFAOYSA-N 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N5/00—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid
- G01N5/04—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid by removing a component, e.g. by evaporation, and weighing the remainder
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Life Sciences & Earth Sciences (AREA)
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- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
Abstract
The invention belongs to the technical field of chemical detection, and particularly discloses a method for detecting the lithium content in lithium phosphate. The detection method of the invention adopts the steps of separating first, separating lithium ions in the lithium phosphate sample to be detected, then burning out, burning out lithium nitrate formed by the separated lithium ions, and then calculating according to the burned-out matter to obtain the content of lithium in the lithium phosphate sample to be detected. By the method for separating the lithium element from the phosphorus element and then measuring the lithium element, the influence of the interference element in the lithium phosphate sample on the test result is obviously reduced, the accuracy of the test result is improved, and the accuracy problem of the lithium phosphate content test is effectively solved. The method has the advantages of direct and simple test and accurate test result.
Description
Technical Field
The invention relates to the technical field of chemical detection, in particular to a method for detecting the content of lithium in lithium phosphate.
Background
At present, the lithium phosphate material is widely used as a lithium source and a phosphorus source in the new energy battery material industry and is used as a raw material for producing lithium iron phosphate. In particular, with the development of new energy automobile industry, the requirements on the quality of raw materials are more and more strict, so that the accurate determination of element lithium in lithium phosphate is also very important. The determination accuracy of lithium element in lithium phosphate has a crucial influence on production control, product performance research, product quality control and the like.
However, at present, no effective and accurate detection method for detecting lithium phosphate exists. At present, the lithium content in lithium phosphate is detected by an ICP method and a flame atomic absorption method. However, the ICP method and the atomic absorption method are high in requirement on an instrument for testing lithium element content, and are mostly used for trace tests, and the lithium element content in the lithium phosphate material is very high, so that the requirement on the instrument testing environment can be met only by multiple dilutions in the testing process. And the operation of repeated dilution is easy to bring errors, so that the accuracy of the lithium content test result in the lithium phosphate can be affected.
Therefore, it is necessary to develop a detection method capable of simply and rapidly determining the lithium content in lithium phosphate so as to meet the development requirements of the new energy battery industry.
Disclosure of Invention
The invention mainly solves the technical problem of providing a simple and rapid method for determining the lithium content in lithium phosphate, which can realize accurate determination of the lithium content in lithium phosphate.
In order to solve the technical problems, the invention provides a method for detecting the lithium content in lithium phosphate, which comprises the following steps:
(1) Dissolving a lithium phosphate sample to be detected by nitric acid to prepare a lithium phosphate sample solution;
(2) Mixing a silver nitrate solution with the lithium phosphate sample solution, regulating the pH value to 4.0-5.8, reacting to generate a silver phosphate precipitate, and carrying out solid-liquid separation to obtain the silver phosphate precipitate and a lithium nitrate filtrate;
(3) Removing silver ions in the lithium nitrate filtrate by precipitation, and carrying out solid-liquid separation to obtain filtrate;
(4) Calcining the filtrate in an insulation way to obtain a lithium nitrate solid loss-on-ignition substance;
(5) And calculating the mass percentage content of lithium in the lithium phosphate sample to be detected according to the mass of the burning loss.
According to the method for detecting the lithium content in the lithium phosphate, firstly, a lithium phosphate sample to be detected is dissolved by nitric acid to prepare a lithium phosphate sample solution; adding water into the pure silver nitrate to prepare a silver nitrate solution; mixing the silver nitrate solution with the lithium phosphate sample solution, regulating the pH value of the mixed solution to 4.0-5.8 by using dilute acetic acid, fully reacting phosphate radical in the mixed solution with silver ions under the condition to generate silver phosphate precipitate, fully releasing lithium ions in lithium phosphate, fully combining the lithium ions with nitrate radical to generate a lithium nitrate solution, and filtering and separating to obtain a lithium nitrate filtrate;
in order to enable phosphate radicals to fully react with silver ions, silver nitrate is in excessive reaction, and at the moment, the lithium nitrate filtrate possibly contains residual unreacted silver ions, so that the silver ions in the lithium nitrate filtrate are further removed by adopting a precipitation method, the influence of the silver ions on a detection result is avoided, and then the filtrate is filtered, and is obtained, wherein the filtrate is a pure lithium nitrate solution;
calcining the filtrate to obtain a loss-on-ignition lithium nitrate solid, and weighing the loss-on-ignition lithium nitrate solid;
and calculating the mass percentage content of lithium in the lithium phosphate sample to be detected according to the mass of the lithium phosphate sample to be detected and the mass of the obtained burning loss.
The detection method of the invention adopts the steps of separating the lithium ions in the lithium phosphate sample to be detected firstly, then burning out the lithium ions, namely burning out the lithium nitrate formed by the separated lithium ions, and then calculating the content of lithium in the lithium phosphate sample to be detected according to the burned-out matter. By the method for separating the lithium element from the phosphorus element and then measuring the lithium element, the influence of the interference element in the lithium phosphate sample on the test result is obviously reduced, the accuracy of the test result is improved, and the accuracy problem of the lithium phosphate content test is effectively solved. The method has the advantages of direct and simple test and accurate test result.
As a preferred embodiment of the present invention, the formula used in calculating the lithium content in the present invention is:
Li(wt,％)＝m 2 /m 1 ×0.10067×100
wherein, -m 1 Representing the mass of a lithium phosphate sample to be detected;
-m 2 indicating the quality of the burn-out.
In the above formula, 0.10067 is the ratio of the molar amount of lithium 6.941 to the molar amount of lithium nitrate burned as a loss product 68.947.
As a preferred embodiment of the present invention, the calcination is carried out at 300 to 500℃and preferably at 350 to 450 ℃.
It was found that the detection result RSD was the smallest and the test result was the most stable, especially when the calcination was carried out at 400 ℃.
As a preferred embodiment of the present invention, the temperature rising rate is controlled to be 2 to 5 ℃ per minute, preferably 2 to 4 ℃ per minute, more preferably 3 ℃ per minute, during the heat-insulating calcination.
As a preferred embodiment of the present invention, in the step (2), the pH of the mixed solution is adjusted to 4.5 to 5.5 by adjusting the pH with dilute acetic acid. Further preferably, the pH is adjusted to about 5.0, and the accuracy of the detection result is high.
As a preferred embodiment of the present invention, the preparation of a lithium phosphate sample solution comprises the steps of: mixing a lithium phosphate sample to be detected with water, adding concentrated nitric acid, and shaking until the lithium phosphate sample is completely dissolved, thus obtaining a lithium phosphate sample solution.
Preferably, the ratio of the lithium phosphate sample to be measured to water is 0.3-2.0 g/mL, namely, 0.3-2.0 g of the lithium phosphate sample to be measured is added into 1mL of water.
Preferably, the concentration of the concentrated nitric acid used is 60 to 68% by mass, more preferably 65%.
Further preferably, the step of preparing a lithium phosphate sample solution is: 1.0-2.0 g of lithium phosphate sample to be measured is weighed and is firstly mixed with 1-3 ml of water, then 1-3 ml of concentrated nitric acid is added, and the mixture is shaken until the mixture is completely dissolved, so that a lithium phosphate sample solution is prepared.
As a preferred embodiment of the present invention, the concentration of the silver nitrate solution is 0.5 to 2.0g/ml.
It is further preferred that the silver nitrate solution is mixed with the lithium phosphate sample solution in a molar ratio of (1.01 to 1.05): 1.
As a more preferable embodiment of the invention, the silver nitrate solution is prepared by adopting a silver nitrate pure product, and the purity of the adopted silver nitrate pure product is more than or equal to 99.5 percent.
During detection, the sample weighing amount of the silver nitrate is slightly larger than the reaction required amount, namely the silver nitrate is in excessive reaction so as to ensure that phosphate radical in lithium phosphate is completely reacted, but the excessive reaction is not proper, so that reagent waste can be caused, the purity of a lithium nitrate solution obtained later can be influenced, and the detection accuracy can be further influenced.
In a preferred embodiment of the invention, in order to improve the detection accuracy, the lithium nitrate filtrate is purified, and silver ions therein are removed by precipitation, preferably by a hydrochloric acid precipitation method.
Further preferably, hydrochloric acid is added to the lithium nitrate filtrate to fully react the silver ions remaining in the solution to generate white precipitate, and then the white precipitate is filtered to obtain a pure lithium nitrate solution.
The invention also provides application of the detection method in lithium content detection of the lithium phosphate material. The method can accurately detect the lithium content in the lithium phosphate material, reduce the influence of interfering elements (such as sulfur and the like) in the lithium phosphate sample on the test result, and effectively solve the problem of accuracy of lithium phosphate content test because the calcined burned-out matter is only the lithium-containing compound.
Drawings
FIG. 1 is a photograph of silver phosphate precipitate obtained in example 5 of the present invention, the precipitate being yellow;
FIG. 2 is a photograph of the burned product obtained by the thermal insulation calcination in example 5 of the present invention, which is silver gray.
Detailed Description
The technical scheme of the invention is described in detail through specific examples.
Test group 1
The test procedure is as follows:
(1) Weighing 1g of lithium phosphate sample to be measured, wherein the theoretical value of the mass percent content of lithium in the sample is 17.5%, adding 2ml of deionized water into the weighed lithium phosphate sample to be measured, adding 2ml of concentrated nitric acid, and shaking until the sample is completely dissolved to obtain a lithium phosphate sample solution;
(2) Weighing 4.5g of pure silver nitrate, wherein the purity of the pure silver nitrate is more than or equal to 99.5%, adding 5ml of deionized water for complete dissolution, and preparing silver nitrate solution by clarifying and transparentizing the solution;
(3) Mixing a silver nitrate solution with a lithium phosphate sample solution, adding a dilute acetic acid solution to regulate the pH value of the mixed solution, completely reacting phosphate radical with silver ions to generate yellow silver phosphate precipitate, and filtering and separating to obtain the silver phosphate precipitate and a lithium nitrate filtrate;
(4) Adding 1ml of concentrated hydrochloric acid (the mass percentage concentration is 37%) into the lithium nitrate filtrate, completely reacting the rest silver ions in the solution to generate white precipitate, filtering, separating and removing the silver-containing precipitate, and collecting filtrate with the volume of not more than 300ml;
(5) Calcining the filtrate obtained in the step (4) at the temperature of 400 ℃, wherein the temperature rising rate is 3 ℃/min during the heat-preserving calcining, calcining to constant weight to obtain a lithium nitrate solid as a lost material, and weighing the lost material;
(6) And calculating to obtain the mass percentage content of lithium in the lithium phosphate sample to be detected according to the mass of the lithium phosphate sample to be detected and the mass of the burned-out product.
Wherein, the formula adopted in the calculation is:
Li(wt,％)＝m 2 /m 1 ×0.10067×100
in the formula, -m 1 The mass of the lithium phosphate sample to be detected is 1.5g;
-m 2 indicating the mass of the burn-out;
0.10067 is the molar ratio of the molar amount of lithium to the molar amount of lithium nitrate of the burn-out.
According to the test process, in the step (3), the pH value of the mixed solution is regulated by adopting a dilute acetic acid solution formed by mixing acetic acid and water according to the volume ratio of 2:1.
The differences between examples 1 to 3 in the following tables are that in the step (3), when the pH of the mixed solution is adjusted with a dilute acetic acid solution, the adjusted pH is 4.0, 5.0 and 6.0, respectively, and the other steps are the same.
The test results of the mass percent content of lithium in the lithium phosphate sample to be measured obtained through calculation are shown in the following table 1.
TABLE 1
As can be seen from the data of examples 1 to 3 of the above table, in the step (3), when the pH value of the mixed solution is adjusted to about 5.0, the test result is closest to the theoretical value, the relative error with the theoretical value is minimal, the RSD is small, and the test result is relatively more stable.
In order to ensure the accuracy of the test results, it is preferable to adjust the pH of the mixed solution to about 5.0 in the step (3) by using a dilute acetic acid solution.
Test group 2
The test procedure is as follows:
(1) Weighing 1g of lithium phosphate sample to be measured, wherein the theoretical value of the mass percent content of lithium in the sample is 17.5%, adding 2ml of deionized water into the weighed lithium phosphate sample to be measured, adding 2ml of concentrated nitric acid, and shaking until the sample is completely dissolved to obtain a lithium phosphate sample solution;
(2) Weighing 4.5g of pure silver nitrate, wherein the purity of the pure silver nitrate is more than or equal to 99.5%, adding 5ml of deionized water for complete dissolution, and preparing silver nitrate solution by clarifying and transparentizing the solution;
(3) Mixing a silver nitrate solution with a lithium phosphate sample solution, then adopting a dilute acetic acid solution prepared by mixing acetic acid and water according to a volume ratio of 2:1 to adjust the pH value of the mixed solution, adding the dilute acetic acid solution to adjust the pH value of the mixed solution to 5.0, completely reacting phosphate radical with silver ions to generate yellow silver phosphate precipitate, and then filtering and separating to obtain the silver phosphate precipitate and lithium nitrate filtrate;
(4) Adding 1ml of concentrated hydrochloric acid into the lithium nitrate filtrate, completely reacting the rest silver ions in the solution to generate white precipitate, filtering, separating and removing silver-containing precipitate, and collecting filtrate with volume not more than 300ml;
(5) Calcining the filtrate obtained in the step (4) at a temperature-maintaining speed of 3 ℃/min, calcining to constant weight, calcining to obtain a lithium nitrate solid as a loss-on-fire substance, and weighing the loss-on-fire substance;
(6) And calculating to obtain the mass percentage content of lithium in the lithium phosphate sample to be detected according to the mass of the lithium phosphate sample to be detected and the mass of the burned-out product.
Wherein, the formula adopted in the calculation is:
Li(wt,％)＝m 2 /m 1 ×0.10067×100
in the formula, -m 1 The mass of the lithium phosphate sample to be detected is 1.5g;
-m 2 indicating the mass of the burn-out;
0.10067 is the molar ratio of the molar amount of lithium to the molar amount of lithium nitrate of the burn-out.
The difference between example 4 and example 6 in the following table is that in step (5), the temperature of the calcination for heat preservation was selected to be 300℃and 400℃and 500℃respectively, and the other steps were the same.
The test results of the mass percent content of lithium in the lithium phosphate sample to be measured obtained through calculation are shown in the following table 2.
A photograph of the silver phosphate precipitate obtained in example 5 is shown in fig. 1, and the precipitate is yellow; the photo of the burned-out product obtained by the thermal insulation calcination in example 5 is shown in FIG. 2 and is silver gray.
TABLE 2
As is evident from the data of examples 4-6 of the above tables, the test results also differed at different holding calcination temperatures. The test results are smaller at 300 ℃ or 500 ℃; at 400 ℃, the test result is closest to the theoretical value, the RSD is minimum, and the test result is most stable. Therefore, the calcination temperature is preferably about 400 ℃.
Comparative example
1.5g of lithium phosphate sample to be detected is weighed, the theoretical mass percent content of lithium in the sample is 17.5%, and the lithium content in the sample is detected by adopting the existing ICP method. And compared to the data of example 5, see in particular table 3 below.
TABLE 3 Table 3
As can be seen from the comparison of Table 3, the detection method of the present invention has higher accuracy and better stability than the ICP method.
While the invention has been described in detail in the foregoing general description, embodiments and experiments, it will be apparent to those skilled in the art that modifications and improvements can be made thereto. Accordingly, such modifications or improvements may be made without departing from the spirit of the invention and are intended to be within the scope of the invention as claimed.
Claims (16)
1. The method for detecting the lithium content in the lithium phosphate is characterized by comprising the following steps:
(1) Dissolving a lithium phosphate sample to be detected by nitric acid to prepare a lithium phosphate sample solution;
(2) Mixing a silver nitrate solution with the lithium phosphate sample solution, regulating the pH value to 4.0-5.8, reacting to generate a silver phosphate precipitate, and carrying out solid-liquid separation to obtain the silver phosphate precipitate and a lithium nitrate filtrate;
(3) Removing silver ions in the lithium nitrate filtrate by precipitation, and carrying out solid-liquid separation to obtain filtrate;
(4) Calcining the filtrate at 300-450 ℃ to obtain a lithium nitrate solid loss-on-ignition product;
(5) And calculating the mass percentage content of lithium in the lithium phosphate sample to be detected according to the mass of the burning loss.
2. The method of claim 1, wherein the calculation uses the formula:
Li(wt,％)＝m 2 /m 1 ×0.10067×100
wherein, -m 1 Representing the mass of a lithium phosphate sample to be detected;
-m 2 indicating the quality of the burn-out.
3. The method according to claim 1 or 2, wherein the calcination is performed at 350 to 450 ℃.
4. The method according to claim 3, wherein the calcination is performed at 350 to 400 ℃.
5. The method according to claim 3, wherein the calcination is performed at 400 ℃.
6. The method according to claim 1 or 2, wherein the temperature rise rate upon calcination is 2 to 5 ℃/min.
7. The method according to claim 6, wherein the temperature rise rate during calcination is 2 to 4 ℃/min.
8. The method according to claim 6, wherein the temperature rise rate upon calcination is 3 ℃/min.
9. The method according to claim 1 or 2, wherein in step (2), acetic acid is used to adjust the pH.
10. The method according to claim 1 or 2, wherein in the step (2), the pH is adjusted to 4.5 to 5.5.
11. The method according to claim 10, wherein in step (2), the pH is adjusted to 5.0.
12. The method of claim 1 or 2, wherein preparing a lithium phosphate sample solution comprises the steps of: and mixing the lithium phosphate sample to be detected with water, and then adding concentrated nitric acid until the lithium phosphate sample is dissolved, thus obtaining the lithium phosphate sample solution.
13. The method according to claim 12, wherein the ratio of the lithium phosphate sample to be measured to water is 0.3-2.0 g/mL.
14. The method according to claim 1 or 2, wherein the concentration of the silver nitrate solution is 0.5 to 2.0g/mL, and/or the silver nitrate solution is mixed with the lithium phosphate sample solution, wherein the molar ratio of silver nitrate to lithium phosphate is (1.01 to 1.05): 1.
15. The method according to claim 1 or 2, wherein silver ions in the lithium nitrate filtrate are removed by precipitation with hydrochloric acid.
16. Use of the detection method according to any one of claims 1 to 15 for detecting the lithium content of a lithium phosphate material.
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| CN113533309A (en) * | 2021-07-13 | 2021-10-22 | 湖北亿纬动力有限公司 | Method for testing content of iron element in lithium iron phosphate material |
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