Method for detecting lithium content in solution for producing aluminum oxide by Bayer process

Abstract

The invention discloses a method for detecting the content of lithium in a solution for producing aluminum oxide by a Bayer process, and belongs to the field of chemical analysis. The method for detecting the lithium content in the solution for producing the aluminum oxide through the Bayer process comprises the following steps: S1, preparing a standard solution containing an aluminum and sodium substrate, adding strontium chloride, testing the standard solution through an atomic absorption spectrometer, and drawing to obtain a concentration-absorbance standard curve; s2, taking a to-be-detected solution for producing aluminum oxide by a Bayer process, performing acid treatment, adding strontium chloride, and then diluting to a constant volume; and S3, testing the treated to-be-detected solution through an atomic absorption spectrometer, and substituting the obtained absorbance into a concentration-absorbance standard curve to obtain the lithium content in the to-be-detected solution for producing aluminum oxide through the Bayer process. According to the method, the lithium ion concentration of the Bayer solution in the aluminum oxide production process is measured by adding the aluminum substrate, the sodium substrate and the strontium chloride into the standard solution through the atomic absorption spectrometer, spectral line interference is small, the analysis speed is high, and the accuracy is high.

Description

Technical Field

[0001] The invention belongs to the field of chemical analysis, and in particular relates to a method for detecting the lithium content in a solution produced by a Bayer process for producing aluminum oxide. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Bauxite is an important raw material for the production of alumina. my country's bauxite is mainly diaspore type, with a small amount of boehmite type and gibbsite type. The main components of bauxite are aluminum oxide, silicon dioxide, iron oxide, titanium dioxide, and a small amount of sulfide, organic matter, potassium oxide, sodium oxide, calcium oxide, magnesium oxide, phosphorus pentoxide, vanadium pentoxide and trace amounts of manganese, zinc, strontium, zirconium, gallium, chromium, lithium and other element oxides. In the process of producing alumina, lithium oxide in bauxite is easily dissolved by alkaline solution and enters sodium aluminate solution, and enters alumina products along with the production process. When alumina products rich in lithium oxide are used for electrolysis of aluminum, lithium oxide will react with electrolyte to generate lithium fluoride and accumulate in the electrolytic cell, which has a great impact on the electrolysis process. On the other hand, lithium and its compounds are widely used in energy, chemical, medical and other fields. They are important energy materials and the core materials of lithium batteries.

[0004] In recent years, with the development of new energy vehicles and the demand for energy storage, lithium batteries have developed rapidly, which in turn has driven the market demand for lithium and its compounds. Therefore, upstream alumina production companies need to choose a suitable method to detect the content of lithium ions in the production process of alumina. If the lithium ion content reaches a certain concentration, lithium adsorption and impurity removal can be carried out to produce by-product lithium carbonate, and the lithium content in alumina can be reduced to improve the quality of alumina products to meet the needs of electrolytic aluminum companies. The production of by-product lithium carbonate also increases the revenue of alumina plants. The country has corresponding testing standards for the content of lithium in alumina (GB / T6609.19-2018), but due to the high alkali and high aluminum in the Bayer solution, there is a large interference in the measurement process, and the detection results of lithium concentration in the Bayer solution are low in accuracy. Therefore, it is of great significance to provide a method for detecting the lithium content in the solution of alumina produced by the Bayer process with fast analysis speed and high accuracy. Summary of the invention

[0005] In order to solve the shortcomings of the prior art, the purpose of the present invention is to provide a method for detecting the lithium content in a solution of alumina produced by the Bayer process, which solves the technical problem in the prior art of poor stability of test data due to excessive interference from high alkali and high aluminum in the Bayer solution.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] In one aspect, the present invention provides a method for detecting the lithium content in a solution of alumina produced by the Bayer process, comprising the following steps:

[0008] S1. Prepare a standard solution containing aluminum and sodium substrates, add a chemical modifier, and test the standard solution by atomic absorption spectrometer to draw a concentration-absorbance standard curve;

[0009] S2, taking the solution to be tested produced by the Bayer process of producing alumina, subjecting it to acid treatment, adding a chemical modifier, and then diluting and fixing the volume;

[0010] S3. Testing the treated solution by atomic absorption spectrometer, substituting the obtained absorbance into the standard curve of concentration-absorbance, and obtaining the lithium content in the solution to be tested for producing alumina by the Bayer process.

[0011] Furthermore, the solution to be tested in the Bayer process for producing alumina is a Bayer solution, which includes Bayer crude liquor, Bayer refined liquor, seed liquor, circulating liquor and evaporated liquor in the alumina production process.

[0012] The test body in Bayer solution is sodium aluminate solution, and aluminum, sodium base and strontium chloride are added to improve the test accuracy.

[0013] The lithium content in Bayer solution is 0-80 mg / L.

[0014] Furthermore, in step S1, the standard solution containing aluminum and sodium substrates includes a lithium standard solution containing aluminum and sodium substrates and a blank standard solution containing aluminum and sodium substrates.

[0015] Furthermore, several lithium standard solutions of different concentrations are prepared for drawing a standard curve, wherein the number of the lithium standard solutions is ≥ 4, and the dilution multiple is 50-500 times.

[0016] Further, in step S1, the aluminum and sodium substrates are aluminum nitrate and sodium nitrate, aluminum chloride and sodium chloride, or aluminum sulfate and sodium sulfate;

[0017] The ratio of the aluminum substrate to the aluminum content in the Bayer process aluminum oxide solution to be tested is (0.8-1.2): (150-200), g: g / L; the ratio of the sodium substrate to the sodium content in the Bayer process aluminum oxide solution to be tested is (0.1-0.4): (50-100), g: g / L. The amount of A1 and Na substrate added is calculated according to the aluminum and sodium contents in the solution to be tested.

[0018] Furthermore, in step S1, the chemical modifier is strontium chloride. The general regulations require a recovery rate of 95% to 105%. When strontium chloride is added as a chemical modifier, the detection accuracy will be greatly improved, and it can be further refined on the basis of meeting the general regulations. However, other chemical modifiers, such as lanthanum chloride, do not significantly improve the detection accuracy and may not meet the above regulations.

[0019] The volume ratio of the strontium chloride solution to the solution to be detected is (0.8-1.2):1, preferably 1:1. The concentration of the strontium chloride solution is 90-110 g / L, preferably 100 g / L.

[0020] Furthermore, in step S1, an acid is added. The acid is one or a combination of hydrochloric acid, nitric acid or sulfuric acid; the volume ratio of the acid solution to the solution to be detected is (4-6):1, preferably 5:1. The concentration of the acid solution is 4-7 mol / L, preferably 6 mol / L.

[0021] In the lithium standard solution containing aluminum and sodium substrates and the blank standard solution containing aluminum and sodium substrates, the added amounts of aluminum and sodium substrates, chemical modifiers and acid solutions are the same, and the concentrations of the chemical modifiers and acid solutions are the same.

[0022] Preferably, in step S1, the preparation of a standard solution containing aluminum and sodium substrates, the addition of corresponding chemical modifiers, the testing of the standard solution by an atomic absorption spectrometer, and the drawing of a concentration-absorbance standard curve specifically include:

[0023] (1) Take a certain amount of lithium single element standard solution (concentration is 1000 mg / L), add water to make up to volume, and shake well (concentration is 10 mg / L) to obtain the lithium standard working solution.

[0024] (2) Preparation of standard solutions containing base: Pipette different volumes of lithium standard working solution into volumetric flasks respectively, and add a certain amount of aluminum compound and sodium compound as base. The amount of A1 and Na base added is calculated according to the content of aluminum and sodium in the Bayer solution to be tested, add a certain amount of strontium chloride solution, add a certain amount of hydrochloric acid or nitric acid or sulfuric acid, dilute to volume with water, and shake well.

[0025] (3) Preparation of blank standard solution containing substrate: Add water to a volumetric flask, add a certain amount of aluminum compound and sodium compound as substrate. The amount of A1 and Na substrate added is calculated according to the content of aluminum and sodium in the Bayer solution to be tested, add a certain amount of strontium chloride solution, add a certain amount of hydrochloric acid or nitric acid or sulfuric acid, make up to volume with deionized water, and shake well.

[0026] (4) On the atomic absorption spectrometer, use an air-acetylene flame at a wavelength of 670.8 nm and adjust to zero with pure water. When the sample of the solution to be tested is diluted 100 times, the standard concentration input values ​​are: 10, 20, 30, 40, 50. The standard concentration input value calculation formula is:

[0027]

[0028] X: volume of lithium standard working solution pipetted, mL;

[0029] Y: Standard concentration input value.

[0030] Test the blank and standard solutions under optimal conditions and draw concentration-absorbance curves.

[0031] Further, in step S2, the acid is one or a combination of hydrochloric acid, nitric acid or sulfuric acid; the volume ratio of the added acid to the solution to be detected is (4-6): 1, preferably 5: 1. The concentration of the acid solution is 4-7 mol / L, preferably 6 mol / L.

[0032] Furthermore, in step S2, the chemical modifier is strontium chloride; the volume ratio of the strontium chloride solution to the solution to be detected is (0.8-1.2):1, preferably 1:1. The concentration of the strontium chloride solution is 90-110 g / L, preferably 100 g / L.

[0033] Furthermore, in step S2, the solvent for dilution and volume adjustment is water.

[0034] Furthermore, in step S2, the solution to be tested must be fresh and cannot be left standing, and must be filtered immediately after being retrieved. If left standing for a long time, aluminum hydroxide and other precipitates will form in the solution to be tested, causing lithium to be adsorbed by the precipitate, thereby causing inaccurate determination of the lithium content.

[0035] Furthermore, the atomic absorption spectrometer uses an air-acetylene flame, and the test analysis wavelength is 670.8nm or 610.4nm.

[0036] The beneficial effects of the present invention are:

[0037] The present invention uses an atomic absorption spectrometer to add aluminum, sodium substrate and chemical modifier strontium chloride to a standard solution to determine the lithium ion content of the Bayer solution in the alumina production process, with less spectral line interference, fast analysis speed and high accuracy.

[0038] Compared with the prior art, the present invention fills the gap in the prior art for detecting the lithium content of Bayer solution in the alumina production process, and realizes the testing of the lithium content in Bayer concentrate, seed liquor, circulating liquor, etc. in the Bayer process of alumina production. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0040] Figure 1 This is a standard curve diagram of concentration-absorbance in Example 1 of the present invention. DETAILED DESCRIPTION

[0041] The reagents and instruments used in the present invention can be purchased from the market.

[0042] The instruments and reagents used in the following examples are as follows:

[0043] For the flame atomic absorption spectrometer, an atomic absorption spectrophotometer AA320N Plus was selected, with a wavelength of 670.8 nm, an element slit of 0.2 nm, a lamp current of 2.5 mA, an air flow rate of 6.5 L / min, an acetylene flow rate of 1.5 L / min, and a burner head height of 10 mm.

[0044] Lithium single element standard solution (1000mg / L), high-grade pure nitric acid (65-68%), high-grade pure hydrochloric acid (36-38%), high-grade pure sodium chloride (≥99.8%), analytical pure aluminum chloride hexahydrate (98%), analytical pure strontium chloride hexahydrate (≥99.5%), deionized water resistivity ≥18.25MΩ.

[0045] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0046] Example 1

[0047] 1. Preparation of standard solution containing base lithium

[0048] (1) Lithium standard solution: Pipette 1 mL of lithium standard solution (concentration 1000 mg / L) and add pure water to make up to 100 mL, and shake well (concentration 10 mg / L).

[0049] (2) Preparation of base series lithium standard solution: Pipette 1 mL, 2 mL, 3 mL, 4 mL, and 5 mL of lithium standard working solution (10 mg / L) into a 100 mL volumetric flask, add 0.84 g AlCl3·6H2O (the aluminum oxide content in Bayer sperm is about 180 g / L), 0.2 g NaCl (the sodium content in Bayer sperm is about 80 g / L), 1 mL strontium chloride solution (concentration 100 g / L), and 5 mL hydrochloric acid (concentration 1+1), dilute to 100 mL with pure water, and shake well.

[0050] (3) Preparation of blank standard solution containing substrate: 50 mL of deionized water, add 0.84 g of AlCl3·6H2O, 0.2 g of NaCl, 1 mL of strontium chloride solution (concentration 100 g / L), 5 mL of hydrochloric acid (concentration 1+1), dilute to 100 mL with pure water, and shake well.

[0051] (4) On an atomic absorption spectrometer, use an air-acetylene flame at a wavelength of 670.8 nm and adjust the zero value with pure water. The standard concentration input values ​​are: 10, 20, 30, 40, and 50.

[0052] Standard concentration input value calculation formula:

[0053]

[0054] X: volume of lithium standard working solution pipetted, mL, X = 1, 2, 3, 4, 5;

[0055] Y: standard concentration input value, mg / L, Y=10, 20, 30, 40, 50.

[0056] Test the blank and standard solutions under the best conditions and draw the concentration-absorbance curve, such as Figure 1 shown.

[0057] 2. Sample processing

[0058] (1) Take Bayer semen samples A and B from two production lines, filter them immediately after processing, take 1 mL of the filtrate and place it in a 100 mL volumetric flask, add 5 mL of hydrochloric acid (concentration 1+1) and shake until completely dissolved, add 1 mL of strontium chloride solution (concentration 100 g / L), dilute to 100 mL with pure water, and shake well.

[0059] 3. Sample test analysis

[0060] The sample was tested and analyzed on an atomic absorption spectrometer at a wavelength of 670.8 nm using an air-acetylene flame. The test results are directly the content of lithium in the semen sample in mg / L. The test results of sample A and sample B are shown in Table 1.

[0061] Table 1

[0062] Sample name Measurement value (mg / L) Bayer semen sample A 35.06 Bayer semen sample B 38.20

[0063] According to the standard addition method, a recovery test is performed. Recovery = (measured content - sample content) / added amount × 100%; the general requirement is that the recovery is 95% to 105%. The recovery of the lithium salt content determined by the standard addition-atomic absorption flame method of the present invention is 98.67% to 100.67% (as shown in Table 2 below). This shows that the determination results of this detection method are accurate and reliable.

[0064] Table 2

[0065]

[0066] Embodiment 2:

[0067] 1. Preparation of standard solution containing base lithium

[0068] (1) Lithium standard solution: Pipette 1 mL of lithium standard solution (concentration 1000 mg / L) and add pure water to make up to 100 mL, and shake well (concentration 10 mg / L).

[0069] (2) Preparation of base series lithium standard solution: Pipette 1 mL, 2 mL, 3 mL, 4 mL, and 5 mL of lithium standard working solution (10 mg / L) into a 100 mL volumetric flask, add 0.42 g AlCl3·6H2O (the content of aluminum oxide in the Bayer seed solution is about 90 g / L), 0.3 g NaCl (the content of sodium in the Bayer seed solution is about 120 g / L), 1 mL strontium chloride solution (concentration 100 g / L), and 5 mL nitric acid (concentration 30%), dilute to 100 mL with pure water, and shake well.

[0070] (3) Preparation of blank standard solution containing substrate: 50 mL of deionized water, add 0.42 g of AlCl3·6H2O, 0.3 g of NaCl, 1 mL of strontium chloride solution (concentration 100 g / L), 5 mL of nitric acid (concentration 30%), dilute to 100 mL with pure water, and shake well.

[0071] (4) On an atomic absorption spectrometer, use an air-acetylene flame at a wavelength of 670.8 nm and adjust the zero value with pure water. The standard concentration input values ​​are: 10, 20, 30, 40, and 50.

[0072] Standard concentration input value calculation formula:

[0073]

[0074] X: volume of lithium standard working solution pipetted, mL, X = 1, 2, 3, 4, 5;

[0075] Y: standard concentration input value, mg / L, Y=10, 20, 30, 40, 50.

[0076] Test the blank and standard solutions under optimal conditions and draw concentration-absorbance curves.

[0077] 2. Sample processing

[0078] (1) Take Bayer seed liquor samples C and D from two production lines, filter them immediately after processing, take 1 mL of the filtrate and place it in a 100 mL volumetric flask, add 5 mL of nitric acid (concentration 30%) and shake until completely dissolved, add 1 mL of strontium chloride solution (concentration 100 g / L), dilute to 100 mL with pure water, and shake well.

[0079] 3. Sample test analysis

[0080] The sample was tested and analyzed on an atomic absorption spectrometer at a wavelength of 670.8 nm using an air-acetylene flame. The test results are directly the lithium content in the semen sample in mg / L. The test results of sample C and sample D are shown in Table 3.

[0081] Table 3

[0082] Sample name Measurement value (mg / L) Bayer seed liquor sample C 8.02 Bayer seed liquor sample D 9.26

[0083] According to the standard addition method, the recovery rate test is performed, and the recovery rate = (measured content - sample content) / added amount × 100%; the general regulations require a recovery rate of 95% to 105%. The recovery rate of the lithium salt content determined by the standard addition-atomic absorption flame method of the present invention is 99.4% to 100.22% (as shown in Table 4 below). This shows that the determination results of this detection method are accurate and reliable.

[0084] Table 4

[0085]

[0086] Example 3

[0087] The difference from Example 1 is that the solution to be tested is Bayer crude solution in the alumina production process.

[0088] Example 4

[0089] The difference from Example 1 is that the solution to be detected is the circulating mother liquor in the alumina production process.

[0090] Example 5

[0091] The difference from Example 1 is that the solution to be detected is the evaporated mother liquor in the production process of aluminum oxide.

[0092] Comparative Example 1

[0093] 1. Preparation of standard solution containing base lithium

[0094] (1) Lithium standard solution: Pipette 1 mL of lithium standard solution (concentration 1000 mg / L) and add pure water to make up to 100 mL, and shake well (concentration 10 mg / L).

[0095] (2) Preparation of standard solutions without substrate: Pipette 1 mL, 2 mL, 3 mL, 4 mL, and 5 mL of lithium standard working solution (10 mg / L) into a 100 mL volumetric flask, add 1 mL of strontium chloride solution (concentration 100 g / L), 5 mL of nitric acid (concentration 30%), dilute to 100 mL with pure water, and shake well.

[0096] (3) Preparation of blank standard solution without substrate: 50 mL of deionized water, 1 mL of strontium chloride solution (concentration 100 g / L), 5 mL of nitric acid (concentration 30%), dilute to 100 mL with pure water, and shake well.

[0097] (4) On an atomic absorption spectrometer, use an air-acetylene flame at a wavelength of 670.8 nm and adjust the zero value with pure water. The standard concentration input values ​​are: 10, 20, 30, 40, and 50.

[0098] Standard concentration input value calculation formula:

[0099]

[0100] X: Volume of lithium standard working solution pipetted, mL, X=1, 2, 3, 4, 5.

[0101] Y: standard concentration input value, mg / L, Y=10, 20, 30, 40, 50.

[0102] Test the blank and standard solutions under optimal conditions and draw concentration-absorbance curves.

[0103] 2. Sample processing

[0104] (1) Take Bayer semen samples E and F from two production lines, filter them immediately after processing, take 1 mL of the filtrate and place it in a 100 mL volumetric flask, add 5 mL of nitric acid (concentration 30%) and shake until completely dissolved, add 1 mL of strontium chloride solution (concentration 100 g / L), dilute to 100 mL with pure water, and shake well.

[0105] 3. Sample test analysis

[0106] The samples were tested and analyzed on an atomic absorption spectrometer at a wavelength of 670.8 nm using an air-acetylene flame. The test results were directly expressed as the lithium content in the semen sample in mg / L. The test results of Sample E and Sample F are shown in Table 5.

[0107] Table 5

[0108] Sample name Measurement value (mg / L) Bayer Sperm Sample E 18.68 Bayer Sperm Sample F 19.29

[0109] According to the standard addition method, the recovery rate test is performed, and the recovery rate = (measured content - sample content) / added amount × 100%; the general regulations require a recovery rate of 95% to 105%. The recovery rate of the lithium salt content determined by the standard addition-atomic absorption flame method of the present invention is 73.60% to 73.75% (as shown in Table 6 below). This shows that the determination result of this detection method is obviously low.

[0110] Table 6

[0111]

[0112] Comparative Example 2

[0113] Different from Example 1, strontium chloride is not added to the preparation of the base series lithium standard solution, and no anti-interference strontium chloride is added to the sample to be tested. According to the standard addition method, a recovery test is performed, and the recovery rate = (measured content - sample content) / added amount × 100%; the test results are shown in Table 7 below.

[0114] Table 7

[0115]

[0116] The general regulations require a recovery rate of 95% to 105%. The recovery rate of the lithium salt content determined by the standard addition-atomic absorption flame method of the present invention is 90.87% to 106.13%, indicating that the accuracy of the determination result of this detection method is insufficient.

[0117] Comparative Example 3

[0118] The difference from Example 1 is that the preparation of the base series lithium standard solution is added with the same amount of lanthanum chloride, and the sample to be tested is also added with the same amount of lanthanum chloride. According to the standard addition method, the recovery rate test is performed, and the recovery rate = (measured content - sample content) / added amount × 100%; the test results are shown in Table 8 below.

[0119] Table 8

[0120]

[0121] The general regulations require a recovery rate of 95% to 105%. The recovery rate of the lithium salt content determined by the standard addition-atomic absorption flame method of the present invention is 92.20% to 107.80%, indicating that the accuracy of the determination result of this detection method is insufficient.

[0122] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for detecting the lithium content in a solution produced by the Bayer process for producing alumina, characterized in that: The following steps are involved: S1. Prepare a standard solution containing aluminum and sodium substrates, add a chemical modifier, and test the standard solution by atomic absorption spectrometer to draw a concentration-absorbance standard curve; S2, taking the solution to be tested produced by the Bayer process of producing alumina, subjecting it to acid treatment, adding a chemical modifier, and then diluting and fixing the volume; S3. Testing the treated solution by atomic absorption spectrometer, substituting the obtained absorbance into the standard curve of concentration-absorbance, and obtaining the lithium content in the solution to be tested for producing alumina by the Bayer process.

2. The method for detecting the lithium content in the solution of the Bayer process for producing alumina according to claim 1, characterized in that: The solution to be tested in the Bayer process for producing aluminum oxide includes Bayer crude liquor, Bayer refined liquor, seed mother liquor, circulating mother liquor and evaporated mother liquor in the process of aluminum oxide production.

3. The method for detecting the lithium content in the solution of the Bayer process for producing alumina according to claim 1, characterized in that: In step S1, the standard solution containing aluminum and sodium as substrates includes a lithium standard solution containing aluminum and sodium as substrates and a blank standard solution containing aluminum and sodium as substrates.

4. The method for detecting the lithium content in the solution of the Bayer process for producing alumina according to claim 1, characterized in that: Prepare a number of lithium standard solutions of different concentrations for drawing a standard curve, wherein the number of the lithium standard solutions is ≥ 4; The dilution multiple is 50-500 times.

5. The method for detecting the lithium content in the solution of the Bayer process for producing alumina according to claim 1, characterized in that: In step S1, the aluminum and sodium substrates are aluminum nitrate and sodium nitrate, aluminum chloride and sodium chloride, or aluminum sulfate and sodium sulfate; Or, the ratio of the aluminum content of the aluminum substrate to the aluminum content of the test solution produced by the Bayer process is (0.8-1.2):(150-200), g:g / L; Or, the ratio of the sodium substrate to the sodium content in the test solution of the Bayer process alumina production is (0.1-0.4):(50-100), g:g / L.

6. The method for detecting the lithium content in the solution of the Bayer process for producing alumina according to claim 1, characterized in that: In step S1, the chemical modifier is strontium chloride; The volume ratio of strontium chloride solution to the solution to be tested is (0.8-1.2):1; The concentration of strontium chloride solution is 90-110g / L; Furthermore, in step S1, an acid solution is also added, and the acid is one or a combination of hydrochloric acid, nitric acid or sulfuric acid; The concentration of the acid solution is 4-7 mol / L; the volume ratio of the acid solution to the solution to be tested is (4-6):

1.

7. The method for detecting the lithium content in the solution of the Bayer process for producing alumina according to claim 1, characterized in that: In step S2, the solution to be tested produced by the Bayer process for producing alumina is a fresh solution and cannot be left standing.

8. The method for detecting the lithium content in the solution of the Bayer process for producing alumina according to claim 1, characterized in that: In step S2, the acid is one or a combination of hydrochloric acid, nitric acid or sulfuric acid; The concentration of the acid solution is 4-7 mol / L; The volume ratio of the acid solution to the solution to be tested is (4-6):

1. Further, in step S2, the chemical modifier is strontium chloride; The concentration of the strontium chloride solution is 90-110 g / L; the volume ratio of the strontium chloride solution to the solution to be tested is (0.8-1.2):

1.

9. The method for detecting the lithium content in the solution of the Bayer process for producing alumina according to claim 1, characterized in that: In step S2, the solvent for dilution and volume fixing is water.

10. The method for detecting the lithium content in the solution of the Bayer process for producing alumina according to claim 1, characterized in that: The atomic absorption spectrometer uses an air-acetylene flame, and the test analysis wavelengths are 670.8nm and 610.4nm.

Images