A method for preparing ultrafine lithium tetraborate powder by liquid phase method

Abstract

This invention discloses a liquid-phase method for preparing ultrafine lithium tetraborate powder. First, a lithium bicarbonate solution is prepared using high-purity lithium carbonate. Then, the lithium bicarbonate solution is reacted with an ethanol solution of boric acid. By controlling the amount of boric acid added, the method of addition, and the reaction temperature, wet lithium tetraborate is obtained. The wet lithium tetraborate is then dried twice at different temperatures to obtain a density as high as 1.39 g / cm³. 3 The method of this invention produces ultrafine lithium tetraborate powder; moreover, the lithium tetraborate powder obtained by this invention has a purity of ≥99.99%, making it suitable for fields such as microelectronics, digital technology, optoelectronics, new computers, video transmission, military technology, aerospace, satellite communications, and defense technology. The method of this invention has low energy consumption, simple and easy-to-operate procedures, low cost, and is suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of lithium tetraborate preparation technology, specifically a method for preparing ultrafine lithium tetraborate powder using a liquid phase method. Background Technology

[0002] Borates commonly exhibit supersaturated dissolution in liquid phases, meaning that they do not precipitate as solute in solution but instead form a water glass solution. Even after evaporation and concentration, the solute does not precipitate, resulting in no wet borate powder. Current methods for precipitating borate from water glass solutions involve adding ethanol. However, this method suffers from the following problems in practice: 1. While adding ethanol to the borate water glass solution causes instantaneous precipitate formation, this borate is gel-like and highly viscous, causing it to stick to the stirring device and leading to stirring failure. 2. The resulting gel-like borate requires further addition of large amounts of ethanol under strong stirring to obtain lithium tetraborate powder, resulting in high solvent consumption. Therefore, existing methods for precipitating borate using ethanol suffer from poor production continuity, high equipment requirements, and high costs.

[0003] In addition, high-purity, high-density lithium tetraborate is a novel temperature-compensated surface wave substrate chip and piezoelectric single crystal substrate material, with wide and important applications in many fields such as microelectronics, digital technology, optoelectronics, new computers, video transmission, military technology, aerospace, satellite communications, and defense technology. Lithium tetraborate was produced as early as the beginning of the 20th century, but due to the relatively weak applied chemical technology at that time, it was not widely used in various industries. It wasn't until the 1980s that it gradually began to be used in enamel glazes and lubricating grease components. Later, with the promotion of materials chemistry, lithium tetraborate was gradually used as a buffer and corrosion inhibitor, and also in the development of new materials. In the 21st century, with the innovation of steel smelting technology, lithium tetraborate was used in wavelength dispersive XRF fluorescence spectrometry, AA atomic absorption spectrometry, and ICP to prepare samples for detecting steel components. However, with the continuous advancement of technology, the density produced by traditional methods is approximately 0.7-0.8 g / cm³. 3 High-purity lithium tetraborate can no longer meet the needs of industries such as testing. In order to obtain ultrafine lithium tetraborate, Chinese invention patent CN102838125B adopts a method of crushing lithium tetraborate by mechanical force, then melting it at high temperature, and finally cooling and crystallizing it with water. However, this method has high energy consumption, complex process, high cost, and large loss of lithium tetraborate product. Summary of the Invention

[0004] Based on the above, the purpose of this invention is to provide a method for preparing ultrafine lithium tetraborate powder by liquid phase method, so as to solve the technical problems of difficulty in preparing ultrafine lithium tetraborate, high cost of existing preparation methods, and large product loss.

[0005] To achieve its purpose, the present invention adopts the following technical solution:

[0006] A method for preparing ultrafine lithium tetraborate powder by liquid phase method includes the following steps:

[0007] (1) Pour pure water into the carbonization reactor, turn on the stirring, add high-purity lithium carbonate, and then introduce carbon dioxide to fully react and prepare lithium bicarbonate solution; when the solution is clear and transparent, test the Li content in the lithium bicarbonate solution. If the Li content is between 6-8 g / L, it is a qualified lithium bicarbonate solution, preferably 7.5-8 g / L.

[0008] (2) Take 99.9% boric acid and add it to ethanol. The volume ratio of ethanol to lithium bicarbonate solution in step (1) is 3-4:1 to prepare boric acid ethanol solution.

[0009] (3) The lithium bicarbonate solution in step (1) is added to the ethanol solution of boric acid in step (2) by spraying to carry out the reaction at a temperature of 120-130℃ to obtain a reaction slurry;

[0010] (4) Centrifuge the reaction slurry from step (3) to obtain filtrate and wet lithium tetraborate;

[0011] (5) Wash the wet lithium tetraborate from step (4) with ethanol and centrifuge again to obtain centrifuged lithium tetraborate;

[0012] (6) The centrifuged lithium tetraborate in step (5) is dried once at 100-120℃ to obtain lithium tetraborate powder;

[0013] (7) The lithium tetraborate powder in step (6) is dried twice at 400-450℃ to obtain ultrafine anhydrous lithium tetraborate powder.

[0014] As a further preferred embodiment of the technical solution of the present invention, in step (1), the purity of the high-purity lithium carbonate is ≥99.999%.

[0015] Furthermore, in step (2), the amount of boric acid used is 1.1-1.2 times the theoretical amount used in the reaction with lithium carbonate.

[0016] Furthermore, in step (2), the volume fraction of ethanol is ≥99.7%.

[0017] Furthermore, in step (3), when the lithium bicarbonate solution is added to the ethanol solution of boric acid, the stirring speed is controlled to be 600-800 r / min.

[0018] Furthermore, in step (3), the reaction time is 6-8 hours.

[0019] Furthermore, in step (3), when the lithium bicarbonate solution is added to the ethanol solution of boric acid, a reflux condenser is provided to prevent the high-temperature volatilization of the solution and boric acid from affecting the ratio of boron and lithium, generating other borates, and thus affecting the purity of the prepared lithium tetraborate.

[0020] Furthermore, in step (5), the solid-liquid ratio of the washing process is 1:2-5, and the washing time is 30-60 min.

[0021] Furthermore, in step (6), the pre-drying time is 2-3 hours.

[0022] Furthermore, in step (7), the re-drying time is 2-3 hours.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. This invention first prepares a lithium bicarbonate solution using high-purity lithium carbonate, then reacts the lithium bicarbonate solution with an ethanol solution of boric acid. By controlling the amount of boric acid added, the method of addition, and the reaction temperature, wet lithium tetraborate is obtained. The wet lithium tetraborate is then dried twice at different temperatures to obtain a density as high as 1.39 g / cm³. 3 The method of this invention produces ultrafine lithium tetraborate powder; moreover, the lithium tetraborate powder prepared by this invention has a purity of ≥99.99%, and is suitable for many fields such as microelectronics, digital technology, optoelectronics, new computers, video transmission, military technology, aerospace, satellite communications, and defense technology.

[0025] 2. The method of the present invention has low energy consumption, simple and easy-to-operate process, low cost, and is suitable for large-scale production.

[0026] 3. In this invention, the prepared centrifuged lithium tetraborate is subjected to a second drying process. The first drying process yields lithium tetraborate dry powder, and the second drying process removes the water of crystallization from the lithium tetraborate dry powder after the first drying process, thereby obtaining anhydrous lithium tetraborate powder. Detailed Implementation

[0027] The present invention will now be described in detail with reference to specific embodiments.

[0028] In the following embodiments of the present invention, the purity of high-purity lithium carbonate is 99.999%; the purity of boric acid is 99.9%; and the volume fraction of ethanol is 99.9%.

[0029] Example 1

[0030] (1) Pour 1L of pure water into the carbonization reactor, turn on the stirring, add 42.55g of high-purity lithium carbonate, and then introduce carbon dioxide to fully react and prepare a lithium bicarbonate solution; when the solution is clear and transparent, use atomic absorption spectrometry to test the Li content in the lithium bicarbonate solution. When the Li content is 8g / L, it is a qualified lithium bicarbonate solution.

[0031] (2) Take 170.87g of boric acid (1.2 times the theoretical amount) and add it to 3L of ethanol to prepare boric acid ethanol solution;

[0032] (3) The lithium bicarbonate solution in step (1) is added to the ethanol solution of boric acid in step (2) by spraying. When adding, the stirring speed is controlled at 800 r / min, the reaction temperature is 120℃, and the reaction time is 8h to obtain the reaction slurry. This spraying process is a high temperature reaction process and is equipped with a condensation reflux device to prevent the volatilization of the solution and boric acid, which would affect the purity of the obtained lithium tetraborate.

[0033] (4) Centrifuge the reaction slurry from step (3) to obtain filtrate and wet lithium tetraborate;

[0034] (5) Wash the wet lithium tetraborate from step (4) with ethanol at a solid-liquid ratio of 1:2 for 30 min, and then centrifuge again to obtain centrifuged lithium tetraborate.

[0035] (6) The centrifuged lithium tetraborate from step (5) is dried at 100°C for 3 hours to obtain lithium tetraborate powder;

[0036] (7) The lithium tetraborate powder in step (6) is dried again at 400℃ for 3h to obtain ultrafine anhydrous lithium tetraborate powder.

[0037] The main content, elemental composition, and density of the ultrafine anhydrous lithium tetraborate powder prepared in Example 1 were analyzed, and the results are shown in Table 1.

[0038] Table 1. Main content, elemental composition, and density analysis of ultrafine lithium tetraborate powder in Example 1

[0039]

[0040] Example 2

[0041] The difference between this embodiment and Embodiment 1 is as follows: Step (1) 425.5g of lithium carbonate is used to prepare 10L of lithium bicarbonate solution; Step (2) 1708.7g of boric acid is used to prepare 30L of ethanol slurry; Step (3) 10L of lithium bicarbonate solution is sprayed into 30L of ethanol slurry for reaction. All other steps are the same as in Embodiment 1.

[0042] The main content, elemental composition, and density of the ultrafine lithium tetraborate powder prepared in Example 2 were analyzed, and the results are shown in Table 2.

[0043] Table 2. Main content, elemental composition, and density analysis of ultrafine lithium tetraborate powder in Example 2.

[0044]

[0045] Example 3

[0046] The difference between this embodiment and Embodiment 1 is as follows: Step (1) 4255g of lithium carbonate is used to prepare 100L of lithium bicarbonate solution; Step (2) 17087g of boric acid is used to prepare 300L of ethanol slurry; Step (3) 100L of lithium bicarbonate solution is sprayed into 300L of ethanol slurry for reaction. All other steps are the same as in Embodiment 1.

[0047] The main content, elemental composition, and density of the ultrafine lithium tetraborate powder prepared in Example 3 were analyzed, and the results are shown in Table 3.

[0048] Table 3. Main content, elemental composition, and density analysis of ultrafine lithium tetraborate powder in Example 3.

[0049]

[0050] Example 4

[0051] The difference between this embodiment and Embodiment 1 is that in step (2), 156.63g of boric acid (1.1 times the theoretical amount) is added to 3L of ethanol solution to prepare an ethanol slurry of boric acid. All other steps are the same as in Embodiment 1.

[0052] The main content, elemental composition, and density of the ultrafine lithium tetraborate powder prepared in Example 4 were analyzed, and the results are shown in Table 4.

[0053] Table 4. Main content, elemental composition, and density analysis of ultrafine lithium tetraborate powder in Example 4.

[0054]

[0055] Example 5

[0056] The difference between this embodiment and Embodiment 1 is that in step (2), 163.75g of boric acid (1.15 times the theoretical amount) is added to 3L of ethanol solution to prepare a boric acid ethanol slurry. All other steps are the same as in Embodiment 1.

[0057] The main content, elemental composition, and density of the ultrafine lithium tetraborate powder prepared in Example 5 were analyzed, and the results are shown in Table 5.

[0058] Table 5. Main content, elemental composition, and density analysis of ultrafine lithium tetraborate powder in Example 5.

[0059]

[0060] Table 6 shows a comparison of the main content and density data of lithium tetraborate in Examples 1, 4 and 5.

[0061] Table 6 Comparison of main content and density data of lithium tetraborate in Examples 1, 4, and 5

[0062]

[0063] A comparison of the main content and density data of lithium tetraborate in Examples 1, 4, and 5 shows that using 1.1-1.2 times the theoretical amount of boric acid to prepare lithium tetraborate results in better purity and density, with a purity ≥99.99% and a density ≥1.29 g / cm³. 3 .

[0064] Example 6

[0065] The difference between this embodiment and Embodiment 1 is that the volume ratio of ethanol used in step 2 to the volume of lithium bicarbonate solution used in step 1 is 4:1. All other steps are the same as in Embodiment 1.

[0066] The main content, elemental composition, and density of the ultrafine lithium tetraborate powder prepared in Example 6 were analyzed, and the results are shown in Table 7.

[0067] Table 7. Main content, elemental composition, and density analysis of ultrafine lithium tetraborate powder in Example 6.

[0068]

[0069] Increasing the amount of ethanol did not significantly change the main content, elemental content, or density of the prepared lithium tetraborate. Considering cost, a 3:1 ratio of ethanol to the total ethanol content is preferred.

[0070] Example 7

[0071] The difference between this embodiment and Embodiment 1 is that the stirring speed in step 3 is changed to 600 r / min. All other steps are the same as in Embodiment 1.

[0072] The main content, elemental composition, and density of the ultrafine lithium tetraborate powder prepared in Example 7 were analyzed, and the results are shown in Table 7.

[0073] Table 8. Main content, elemental composition, and density analysis of ultrafine lithium tetraborate powder in Example 7.

[0074]

[0075] Example 8

[0076] The difference between this embodiment and Embodiment 1 is that the stirring speed in step 3 is changed to 700 r / min. All other steps are the same as in Embodiment 1.

[0077] The main content, elemental composition, and density of the ultrafine lithium tetraborate powder prepared in Example 8 were analyzed, and the results are shown in Table 9.

[0078] Table 9. Main content, elemental composition, and density analysis of ultrafine lithium tetraborate powder in Example 8.

[0079]

[0080] Table 10 shows a comparison of the main content and density data of lithium tetraborate in Examples 1, 7 and 8.

[0081] Table 10 Comparison of lithium tetraborate main content and density data in Examples 1, 7, and 8

[0082]

[0083] A comparison of the main content and density data of lithium tetraborate in Examples 1, 7, and 8 shows that preparing lithium tetraborate by reaction at 600-800 r / min yields superior results in terms of purity and density, with a purity ≥99.99% and a density ≥1.26 g / cm³. 3 .

[0084] Example 9

[0085] The difference between this embodiment and Embodiment 1 is that the reaction time in step (3) is changed to 6 hours. All other steps are the same as in Embodiment 1.

[0086] The main content, elemental composition, and density of the ultrafine lithium tetraborate powder prepared in Example 9 were analyzed, and the results are shown in Table 11.

[0087] Table 11. Main content, elemental composition, and density analysis of ultrafine lithium tetraborate powder in Example 2

[0088]

[0089] Example 10

[0090] The difference between this embodiment and Embodiment 1 is that the reaction time in step 3 is changed to 7 hours. All other steps are the same as in Embodiment 1.

[0091] The main content, elemental composition, and density of the ultrafine lithium tetraborate powder prepared in Example 10 were analyzed, and the results are shown in Table 12.

[0092] Table 12. Main content, elemental composition, and density analysis of ultrafine lithium tetraborate powder in Example 10

[0093]

[0094] Table 13 shows a comparison of the main content and density data of lithium tetraborate in Examples 1, 9 and 10.

[0095] Table 13 Comparison of main content and density data of lithium tetraborate in Examples 1, 9, and 10

[0096]

[0097] A comparison of the main content and density data of lithium tetraborate in Examples 1, 9, and 10 shows that preparing lithium tetraborate by reacting for 6-8 hours yields superior results in terms of purity and density, with a purity ≥99.99% and a density ≥1.24 g / cm³. 3 .

[0098] Examples 11-15

[0099] Examples 11-15 are identical to Example 1 in all other steps, except for the lithium content in step (1). The effect of lithium content on whether a clear and transparent solution can be obtained is shown in Table 14.

[0100] Table 14. Effect of lithium content on the availability of a clear and transparent solution.

[0101]

[0102] As can be seen from the data in the above embodiments, when the lithium content is ≤8g / L, lithium carbonate can be completely dissolved into a clear and transparent lithium bicarbonate solution, which is convenient for the next step of spraying reaction to precipitate lithium tetraborate. Considering the dissolved lithium content, the lithium content is preferably selected to be 7.5-8g / L for precise batching.

[0103] Examples 17-23

[0104] Examples 17-23 are identical to Example 1 in all other steps, except for the reaction temperature in step (3). The effect of reaction temperature on the purity of lithium tetraborate is shown in Table 15.

[0105] Table 15 Effect of reaction temperature on the purity of lithium tetraborate

[0106]

[0107] The experimental data from the above examples show that when the reaction temperature is 120-130℃, the purity of the obtained lithium tetraborate is ≥99.99%, and the density of the obtained lithium tetraborate is 1.38 g / cm³. 3 Therefore, the optimal reaction temperature is 120-130℃.

[0108] Examples 24-28

[0109] Examples 24-28 are identical to Example 1 in all other steps, except for the washing solid-liquid ratio in step (5). The effect of the washing solid-liquid ratio on the purity of lithium tetraborate is shown in Table 16.

[0110] Table 16 Effect of washing solid-liquid ratio on the purity of lithium tetraborate

[0111]

[0112] The experimental data from the above embodiments show that when the washing solid-liquid ratio is 1:2, 1:3, 1:4, and 1:5, the purity of the prepared lithium tetraborate is ≥99.99%, and the density of the obtained lithium tetraborate is ≥1.38 g / cm³. 3 Considering cost, a solid-liquid ratio of 1:2 is selected as the optimal washing method.

Claims

1. A method for preparing ultrafine lithium tetraborate powder by liquid phase method, characterized in that, The method comprises the following steps: (1) injecting pure water into a carbonization reactor, starting stirring, adding high-purity lithium carbonate, and then introducing carbon dioxide to fully react to prepare a lithium bicarbonate solution; when the solution is clear and transparent, testing the Li content in the lithium bicarbonate solution, and the Li content being between 6-8 g / L, i.e. the lithium bicarbonate solution is qualified; (2) taking 99.9% boric acid and adding it into ethanol to prepare a boric acid ethanol solution; the volume ratio of ethanol to the lithium bicarbonate solution in step (1) being 3-4:1; (3) adding the lithium bicarbonate solution in step (1) into the boric acid ethanol solution in step (2) by spraying to react, the reaction temperature being 120-130°C, and obtaining a reaction slurry; (4) centrifuging the reaction slurry in step (3) to obtain a filtrate and wet lithium tetraborate; (5) washing the wet lithium tetraborate in step (4) with ethanol, and centrifuging again to obtain centrifuged lithium tetraborate; (6) drying the centrifuged lithium tetraborate in step (5) at 100-120°C for the first time to obtain lithium tetraborate powder; (7) drying the lithium tetraborate powder in step (6) at 400-450°C for the second time to obtain superfine anhydrous lithium tetraborate powder.

2. The method according to claim 1, wherein the method is characterized by, In step (1), the high-purity lithium carbonate has a purity of ≥99.999%.

3. The method of claim 1, wherein the method is a liquid phase method for preparing ultrafine lithium tetraborate powder, characterized in that, In step (2), the amount of boric acid is 1.1-1.2 times the theoretical amount of lithium carbonate.

4. The method of claim 1, wherein the method is a liquid phase method for preparing ultrafine lithium tetraborate powder, characterized in that, In step (2), the volume fraction of ethanol is ≥99.7%.

5. The method of claim 1, wherein the method is a liquid phase method for preparing ultrafine lithium tetraborate powder, characterized in that, In step (3), the stirring speed is controlled to be 600-800 r / min when the lithium bicarbonate solution is added into the boric acid ethanol solution.

6. The method for preparing ultrafine lithium tetraborate powder by liquid phase method as described in claim 5, characterized in that, In step (3), the reaction time is 6-8 h.

7. The method of claim 6, wherein the liquid phase method for preparing ultrafine lithium tetraborate powder is characterized by, In step (3), a condensation reflux device is provided when the lithium bicarbonate solution is added into the boric acid ethanol solution.

8. The method according to any one of claims 1-7, wherein the method is a liquid phase method for preparing ultrafine lithium tetraborate powder, characterized in that, In step (5), the solid-liquid ratio for washing is 1:2-5, and the washing time is 30-60 min.

9. The method according to any one of claims 1-7, wherein the method is a liquid phase method for preparing ultrafine lithium tetraborate powder, characterized in that, In step (6), the first drying time is 2-3 h.

10. The method of claim 9, wherein the liquid phase method for preparing ultrafine lithium tetraborate powder is characterized by, In step (7), the second drying time is 2-3 h.

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