Ion sieve for salt bath purification, preparation method therefor and use method therefor

Abstract

The present application relates to the technical field of ion sieves and provides an ion sieve for salt bath purification, a preparation method therefor, and a use method therefor. The ion sieve comprises the following components in molar percentage on an oxide basis: 45.0-64.0 mol% of SiO2, 2.0-16.0 mol% of Al2O3, 34.0-45.0 mol% of Na2O, 0-3.0 mol% of ZrO2, and 0-2.0 mol% of Y2O3, wherein after the ion sieve has undergone lithium ion absorption for 0.5-24 h in a salt bath at a temperature of 350-550°C, the crystal form of the ion sieve does not change. In the present application, by controlling the ion sieve not to undergo a crystal form change after lithium ion absorption for 0.5-24 h in the salt bath at the temperature of 350-550°C, the ion sieve does not shed fragments after use in the salt bath, so that the salt bath cannot be contaminated, and there is no fragments attached to the surface of tempered glass and affecting the appearance quality thereof. By controlling the mesh size of a mesh container of a composite salt bath additive to be 0.15 mm or more, the composite salt bath additive does not affect the adsorption effect of the ion sieve on salt bath purification, and the lithium ion adsorption efficiency is high; in addition, the influence of the ion sieve on the appearance quality of the tempered glass can be prevented.

Description

Ion sieve for salt bath purification and preparation method and use method thereof

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 25, 2023, with application number CN202311789340.2 and invention name “Ion sieve for salt bath purification, preparation method and use method thereof”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of ion sieves, and in particular to an ion sieve for salt bath purification and a preparation method and a use method thereof. Background Art

[0003] During the chemical strengthening process of glass, alkali metal ions with large ionic radius (such as K + 、Na + ) replaces the alkali metal ions with small ionic radius (such as Na + 、Li + ), a "crowding effect" is generated within a certain depth range, forming a specific stress distribution, hindering the expansion of micro cracks in the glass, thereby achieving the purpose of improving the strength of the glass. At the same time, alkali metal ions with small ion radius will continuously enter the salt bath from the glass, causing Na + 、Li + Although Na + 、Li + The content is only at the ppm level, but it is enough to seriously hinder the normal chemical strengthening process, resulting in a decrease in the stress level of the glass after subsequent strengthening and a significant decrease in mechanical strength, resulting in the final product performance not meeting the use requirements. + The increase in will seriously weaken the degree of lithium-sodium exchange during the chemical strengthening of lithium aluminosilicate glass, resulting in a rapid decrease in the increase in the size of the glass after strengthening, and it is impossible to achieve the deviation range of glass size within 20μm in mobile phone cover applications, which ultimately leads to an increase in the dimensional defective rate of chemically strengthened glass.

[0004] In the prior art, powdered sodium phosphate is added to a salt bath. After the sodium phosphate dissolves in the salt bath, the phosphate radical reacts with the Li + Form lithium phosphate precipitation to reduce the impurity Li in the salt bath + The content of lithium phosphate can extend the service life of the salt bath. However, lithium phosphate precipitation will make the salt bath turbid, and it will take a long time to clarify before it can be used again. In addition, some lithium phosphate particles will adhere to the surface of the tempered glass, causing defects in the glass, which is not conducive to the mass production of chemically strengthened glass. In addition, too much lithium phosphate precipitation at the bottom of the salt bath will reduce the effective working area of ​​the salt bath, making cleaning difficult. In the prior art, silicon-based glass ionomer screens are used to absorb the impurities Li in the salt bath. +, thereby extending the service life of the salt bath; however, the surface of the silicon-based glass ion sieve will fall off after long-term use in a high-temperature salt bath, and the fallen material is easily adsorbed on the surface of the tempered glass, resulting in poor appearance of the tempered glass. Summary of the Invention

[0005] Based on the above situation, the purpose of this application is to address the shortcomings of the existing technical solutions and provide an ion sieve that does not undergo crystal transformation and does not shed fragments after use in a salt bath. It will not contaminate the salt bath, and no fragments will adhere to the surface of the tempered glass to affect the appearance quality of the tempered glass, and has high lithium ion absorption efficiency.

[0006] In a first aspect, the present application provides an ion sieve, which comprises the following components, calculated in molar percentage of oxides:

[0007] SiO2 45.0-64.0mol%;

[0008] Al2O3 2.0-16.0mol%;

[0009] Na2O 34.0-45.0mol%;

[0010] ZrO2 0-3.0mol%;

[0011] Y2O3 0-2.0mol%;

[0012] Wherein, after the ion sieve absorbs lithium ions in a salt bath at a temperature of 350° C. to 550° C. for 0.5 h to 24 h, the crystal form of the ion sieve does not change.

[0013] In some embodiments of the present application, after the ion sieve undergoes sodium-lithium ion exchange in any proportion within the temperature range of 350° C.-550° C., the crystal content in the ion sieve is less than 10 wt %.

[0014] In some embodiments of the present application, the density of the ion sieve is 2.40 g / cm 3 -2.55g / cm 3 .

[0015] In some embodiments of the present application, the ion sieve does not shed fragments after absorbing lithium ions in a salt bath at 350° C. to 550° C. for 0.5 h to 24 h.

[0016] In some embodiments of the present application, the concentration of lithium ions in the salt bath is 50 ppm-400 ppm.

[0017] In a second aspect, the present application provides a method for preparing the ion sieve as described above, comprising: selecting raw material components according to the composition of the ion sieve, mixing them, melting and forming them, and then annealing them to obtain the ion sieve.

[0018] In some embodiments of the present application, the melting temperature is 1300° C.-1650° C., and the melting time is 1 hour-24 hours.

[0019] In some embodiments of the present application, the annealing temperature is 400° C.-450° C., and the annealing time is 12 h-24 h.

[0020] In a third aspect, the present application provides a composite salt bath additive, which is a mesh container and an alkali metal ion adsorbent filled in the mesh container, wherein the alkali metal ion adsorbent is an ion sieve as described above or an ion sieve prepared by the preparation method of the above-mentioned ion sieve; the mesh of the mesh container is greater than 0.15 mm.

[0021] In some embodiments of the present application, the mesh container is at least one of a stainless steel container and a metal container.

[0022] In some embodiments of the present application, the filling rate of the alkali metal ion adsorbent is 20%-80% relative to the volume of the reticulated container.

[0023] In some embodiments of the present application, the alkali metal ions adsorbed by the alkali metal ion adsorbent are lithium ions.

[0024] In a fourth aspect, the present application provides the use of the ion sieve as described above, or the ion sieve prepared by the preparation method of the ion sieve as described above, or the composite salt bath additive as described above in salt bath purification.

[0025] In a fifth aspect, the present application provides a method for using the ion sieve as described above or the ion sieve prepared by the preparation method of the ion sieve as described above, comprising:

[0026] Step 1): providing a salt bath to be purified, wherein the salt bath contains lithium ions;

[0027] Step 2): adding an ion sieve to the salt bath to be purified;

[0028] Step 3): After the ion sieve has reacted in the salt bath to be purified for a certain period of time, the ion sieve is taken out.

[0029] In some embodiments of the present application, the added amount of the ion sieve is 0.5 wt%-5.0 wt% of the mass of the salt bath to be purified.

[0030] In some embodiments of the present application, the temperature of the salt bath is 350°C-550°C.

[0031] In some embodiments of the present application, the concentration of lithium ions in the salt bath is 50 ppm-400 ppm.

[0032] In some embodiments of the present application, the ion sieve reacts in the salt bath to be purified for 3 hours to 24 hours.

[0033] In some embodiments of the present application, the absorption efficiency of the ion sieve is 50%-95%.

[0034] In some embodiments of the present application, when the lithium ion concentration of the salt bath to be purified is 50ppm-400ppm, the amount of the ion sieve added is 0.50wt%-5.00wt% of the mass of the salt bath to be purified, and the reaction time of the ion sieve in the salt bath to be purified is 3h-24h, and the absorption efficiency of the ion sieve is 50%-95%.

[0035] In a sixth aspect, the present application provides a method for using the composite salt bath additive as described above, comprising:

[0036] Step 1): providing a salt bath to be purified, wherein the salt bath contains lithium ions;

[0037] Step 2): adding a composite salt bath additive to the salt bath to be purified;

[0038] Step 3): After the composite salt bath additive has reacted in the salt bath to be purified for a certain period of time, it is taken out.

[0039] In some embodiments of the present application, the added amount of the alkali metal ion adsorbent in the composite salt bath additive is 0.5 wt % to 5.0 wt % of the mass of the salt bath to be purified.

[0040] In some embodiments of the present application, the filling rate of the alkali metal ion adsorbent is 20%-80% relative to the volume of the mesh container.

[0041] In some embodiments of the present application, the temperature of the salt bath is 350°C-550°C.

[0042] In some embodiments of the present application, the concentration of lithium ions in the salt bath is 50 ppm-400 ppm.

[0043] In some embodiments of the present application, the composite salt bath additive reacts in the salt bath to be purified for 3 hours to 24 hours.

[0044] In some embodiments of the present application, the absorption efficiency of the composite salt bath additive is 50%-95%.

[0045] In some embodiments of the present application, when the lithium ion concentration of the salt bath to be purified is 50ppm-400ppm, the added amount of the alkali metal ion adsorbent is 0.50wt%-5.00wt% of the mass of the salt bath to be purified, and the filling rate of the alkali metal ion adsorbent relative to the volume of the mesh container is 20%-80%; the reaction time of the composite salt bath additive in the salt bath to be purified is 3h-24h, and the absorption efficiency of the composite salt bath additive is 50%-95%.

[0046] In the seventh aspect, the present application also provides a chemical strengthening process for lithium-containing microcrystalline glass, which includes the following steps: adding the ion sieve described above in the present application or the ion sieve prepared by the above-mentioned ion sieve preparation method or the above-mentioned composite salt bath additive to the salt bath for chemically strengthening the lithium-containing microcrystalline glass.

[0047] Compared with the prior art, this application has the following beneficial effects:

[0048] 1. This invention controls the ion sieve to absorb lithium ions in a salt bath at a temperature of 350°C to 550°C for 0.5 to 24 hours, so that the crystal content does not exceed 10wt% and the change is minimal, thereby preventing the crystal form from changing. As a result, no fragments fall off, which will not contaminate the salt bath, and no fragments will adhere to the surface of the tempered glass, affecting its appearance quality. In addition, the invention has a high lithium ion adsorption efficiency.

[0049] 2. This application achieves that the composite salt bath additive does not affect the actual adsorption effect of the ion sieve on the salt bath purification by controlling the mesh size of the mesh container of the composite salt bath additive to be larger than 0.15 mm, and has a high adsorption efficiency for lithium ions; at the same time, it can prevent the ion sieve from affecting the appearance quality of the tempered glass. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other embodiments can also be obtained based on these drawings.

[0051] FIG1 is an initial XRD (X-ray diffraction) pattern of the ion sieves of Example 1, Example 5, Comparative Example 1 and Comparative Example 4.

[0052] FIG2 is an XRD pattern of the ion sieves of Example 1, Example 5, Comparative Example 1 and Comparative Example 4 after absorbing lithium ions in a 480° C. salt bath for 8 hours.

[0053] FIG3 is an appearance diagram of the ion sieve in Example 1 after absorbing lithium ions in a 480° C. salt bath for 8 hours.

[0054] FIG4 is an appearance diagram of the ion sieve in Example 6 after absorbing lithium ions in a 480° C. salt bath for 8 hours.

[0055] FIG5 is an appearance diagram of the ion sieve in Comparative Example 2 after absorbing lithium ions in a 480° C. salt bath for 8 hours.

[0056] FIG6 is an appearance diagram of the ion sieve in Comparative Example 3 after absorbing lithium ions in a 480° C. salt bath for 8 hours.

[0057] FIG7 is an appearance diagram of the ion sieve in Comparative Example 5 after absorbing lithium ions in a 480° C. salt bath for 8 hours.

[0058] FIG8 is an appearance diagram of the ion sieve in Comparative Example 6 after absorbing lithium ions in a 480° C. salt bath for 8 hours.

[0059] FIG9 is a polarizing microscope image of the surface of the chemically strengthened glass obtained by adding the ion sieve of Example 2 to the salt bath.

[0060] FIG10 is a polarizing microscope image of the surface of the chemically strengthened glass obtained by adding the ion sieve of Comparative Example 4 into the salt bath.

[0061] FIG11 is a polarizing microscope image of the surface of the chemically strengthened glass obtained after adding the composite salt bath additive A3 to the salt bath.

[0062] FIG12 is a polarizing microscope image of the surface of the chemically strengthened glass obtained after adding the composite salt bath additive B3 to the salt bath. DETAILED DESCRIPTION

[0063] The following will be combined with the accompanying drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0064] In a first aspect, the present application provides an ion sieve, which comprises the following components, calculated in molar percentage of oxides: SiO2 45.0-64.0 mol%; Al2O3 2.0-16.0 mol%; Na2O 34.0-45.0 mol%; ZrO2 0-3.0 mol%; Y2O3 0-2.0 mol%;

[0065] Wherein, after the ion sieve absorbs lithium ions in a salt bath at a temperature of 350° C. to 550° C. for 0.5 h to 24 h, the crystal form of the ion sieve does not change.

[0066] In some embodiments of the present application, the content of SiO2 in the ion sieve can be 45.0mol%, 46.0mol%, 47.0mol%, 48.0mol%, 49.0mol%, 50.0mol%, 51.0mol%, 52.0mol%, 53.0mol%, 54.0mol%, 55.0mol%, 56.0mol%, 57.0mol%, 58.0mol%, 59.0mol%, 60.0mol%, 61.0mol%, 62.0mol%, 63.0mol%, 63.10mol%, 64.0mol%, or a value within the range formed by any two of the above values ​​as endpoints. SiO2 is a forming oxide of the glass network and is used to form a skeleton of the ion sieve network structure composed of covalent bonds. The selection of its composition and content directly affects the adsorption performance of the ion sieve network structure and the thermal stability of the ion sieve in a high temperature environment. Too low SiO2 content will lead to poor formability of the ion sieve, while too high SiO2 content will lead to higher viscosity of the glass, making it difficult to melt the glass.

[0067] In some embodiments of the present application, the content of Al2O3 in the ion sieve can be 2.0mol%, 3.0mol%, 4.0mol%, 5.0mol%, 6.0mol%, 7.0mol%, 8.0mol%, 9.0mol%, 10.0mol%, 11.0mol%, 12.0mol%, 13.0mol%, 14.0mol%, 15.0mol%, 16.0mol%, or a value within a range formed by any two of the above values ​​as endpoints. Al2O3 is a component of the network structure and is beneficial to enhancing the lithium ion absorption rate during the ion sieve's adsorption of lithium ions and improving the ion sieve's resistance to decomposition at high temperatures. However, too high an aluminum oxide content will make it difficult to form the ion sieve.

[0068] In some embodiments of the present application, the content of Na2O in the ion sieve may be 34.0 mol%, 35.0 mol%, 36.0 mol%, 37.0 mol%, 38.0 mol%, 39.0 mol%, 40.0 mol%, 41.0 mol%, 42.0 mol%, 43.0 mol%, 44.0 mol%, 45.0 mol%, or a value within a range formed by any two of the above values ​​as endpoints. Na2O is a network oxide formed by glass, and its content directly affects the ability of the ion sieve to adsorb lithium ions. However, too high a Na2O content may cause the chemical stability of the ion sieve to decrease.

[0069] In some embodiments of the present application, the ZrO2 content in the ion sieve may be 0 mol%, 0.5 mol%, 1.0 mol%, 1.5 mol%, 2.0 mol%, 2.5 mol%, 3.0 mol%, or a value within a range formed by any two of the above values. ZrO2 can improve the chemical and thermal stability of the ion sieve, but a higher ZrO2 content increases the tendency of crystallization.

[0070] In some embodiments of the present application, the Y2O3 content in the ion sieve may be 0 mol%, 0.5 mol%, 1.0 mol%, 1.5 mol%, 2.0 mol%, or a value within a range formed by any two of the above values. Y2O3 can improve the hardness and chemical stability of the ion sieve, but a higher Y2O3 content increases the tendency to crystallize.

[0071] In some embodiments of the present application, the ion sieve has a crystal content of less than 10 wt% before absorbing lithium ions in a salt bath; wherein the crystal content is measured as the proportion of the crystalline phase peak area in the XRD spectrum of the ion sieve. In some embodiments of the present application, the ion sieve has a crystal content of 0.5-9.0 wt%, 0.5-7.0 wt%, 0.5-5.0 wt% before absorbing lithium ions in a salt bath; and can further be 0.5 wt%, 0.8 wt%, 1.5 wt%, 2.8 wt%, 3.7 wt%, 5.0 wt%, 7.0 wt%, 9.0 wt%, 10 wt%, or a value within a range formed by any two of the above values ​​as endpoints.

[0072] In some embodiments of the present application, after the ion sieve undergoes sodium-lithium ion exchange in any proportion within the range of 350°C-550°C, the content of crystals in the ion sieve is less than 10wt%; wherein, the crystal content is measured by the proportion of the crystalline phase peak area in the XRD spectrum of the ion sieve. In some embodiments of the present application, after the ion sieve undergoes sodium-lithium ion exchange in any proportion within the range of 350°C-550°C, the content of crystals in the ion sieve can be 0.5-9.0wt%, 0.5-7.0wt%, 0.5-5.0wt%; further, it can be 0.5wt%, 0.8wt%, 1.5wt%, 2.8wt%, 3.7wt%, 5.0wt%, 7.0wt%, 9.0wt%, 10wt% or a value within the range formed by any two of the above values ​​as endpoints. Without being limited to any theory, the inventors believe that: when the ion sieve absorbs impurity lithium ions in the salt bath, although Na + He Li +ion exchange; however, since the crystal content of the ion sieve before and after absorbing lithium ions is less than 10wt%, the change is small, and the crystal form will not change. Therefore, the structure of the ion sieve before and after absorbing lithium ions is stable, and no fragments will fall off.

[0073] In some embodiments of the present application, the ion sieve absorbs lithium ions for 0.5 h to 24 h in a salt bath at 350° C. to 550° C., and the crystal form of the ion sieve does not change. In some embodiments of the present application, the temperature of the salt bath may be 350° C., 360° C., 370° C., 380° C., 400° C., 410° C., 420° C., 430° C., 440° C., 450° C., 460° C., 470° C., 480° C., 490° C., 500° C., 510° C., 520° C., 530° C., 540° C., 550° C., or a value within a range formed by any two of the above values ​​as endpoints. In some embodiments of the present application, the time for lithium ion absorption can be 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 12h, 16h, 14h, 18h, 20h, 22h, 24h, or a value within the range formed by any two of the above values ​​as endpoints. The present application does not particularly limit the type of salt bath, as long as it contains lithium ions, wherein the impurity ions are mainly lithium ions; for example, it can be a salt bath containing NaNO3, a salt bath containing KNO3, or a mixed salt bath containing NaNO3 and KNO3 in the presence of lithium ions. In some embodiments of the present application, the concentration of lithium ions in the salt bath is 50ppm-400ppm.

[0074] In some embodiments of the present application, the ion sieve absorbs lithium ions in a salt bath at 350°C-550°C for 0.5-24 hours without shedding fragments. In some embodiments of the present application, the temperature of the salt bath can be 350°C, 360°C, 370°C, 380°C, 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, or a value within a range formed by any two of the above values ​​as endpoints. In some embodiments of the present application, the time for lithium ion absorption can be 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 12h, 16h, 14h, 18h, 20h, 22h, 24h, or a value within the range formed by any two of the above values ​​as endpoints. The present application does not particularly limit the type of salt bath, as long as it contains lithium ions, wherein the impurity ions are mainly lithium ions; for example, it can be a salt bath containing NaNO3, a salt bath containing KNO3, or a mixed salt bath containing NaNO3 and KNO3 in the presence of lithium ions. In some embodiments of the present application, the concentration of lithium ions in the salt bath is 50ppm-400ppm.

[0075] In some embodiments of the present application, the concentration of lithium ions in the salt bath may be 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm, 100 ppm, 120 ppm, 140 ppm, 150 ppm, 160 ppm, 170 ppm, 180 ppm, 190 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, or a value within a range formed by any two of the foregoing values ​​as endpoints.

[0076] In some embodiments of the present application, the density of the ion sieve is 2.40 g / cm 3 -2.55g / cm 3 In some embodiments of the present application, the density of the ion sieve may be 2.40 g / cm 3 , 2.41g / cm 3 , 2.42g / cm 3 , 2.43g / cm 3 , 2.44g / cm 3 , 2.45g / cm 3 , 2.46g / cm 3 , 2.47g / cm 3 , 2.48g / cm 3 , 2.49g / cm 3 , 2.50g / cm 3 , 2.51g / cm3 , 2.52g / cm 3 , 2.53g / cm 3 , 2.54g / cm 3 , 2.55g / cm 3 Or a value within the range formed by any two of the above values ​​as endpoints.

[0077] In a second aspect, the present application provides a method for preparing the ion sieve as described above, comprising: selecting raw material components according to the composition of the ion sieve, mixing them, melting and forming them, and then annealing them to obtain the ion sieve.

[0078] The present application does not particularly limit the method of forming. For example, the molten liquid may be injected into a mold or a cast iron platform for forming. After the annealing treatment of the present application, post-processing such as cutting and polishing may be performed to process the ion sieve into a shape commonly found in the field. For example, it may be one or more of granular, sheet-like, porous and / or plate-like. The present application does not particularly limit the size of the shape of the ion sieve. For example, the cutting size may be 50 mm × 50 mm × 0.7 mm.

[0079] In the preparation method of the ion sieve of the present application, the melting temperature is 1300°C-1650°C, and the melting time is 1h-24h. In the preparation method of the ion sieve of the present application, the melting temperature can be 1300°C, 1350°C, 1400°C, 1450°C, 1500°C, 1550°C, 1600°C, 1650°C or a value within the range formed by any two of the above values ​​as endpoints. In the preparation method of the ion sieve of the present application, the melting time can be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 12h, 15h, 17h, 20h, 21h, 24h or a value within the range formed by any two of the above values ​​as endpoints.

[0080] In the preparation method of the ion sieve of the present application, the annealing temperature is 400°C-450°C, and the annealing time is 12h-24h. In the preparation method of the ion sieve of the present application, the annealing temperature can be 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, or a value within the range formed by any two of the above values ​​as endpoints. In the preparation method of the ion sieve of the present application, the annealing time can be 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, or a value within the range formed by any two of the above values ​​as endpoints.

[0081] In a third aspect, the present application provides a composite salt bath additive, which is a mesh container and an alkali metal ion adsorbent filled in the mesh container, wherein the alkali metal ion adsorbent is an ion sieve as described above or an ion sieve prepared by the preparation method of the above-mentioned ion sieve; the mesh of the mesh container is above 0.15 mm.

[0082] In some embodiments of the present application, the filling rate of the alkali metal ion adsorbent relative to the volume of the reticulated container is 20%-80%. In some embodiments of the present application, the filling rate of the alkali metal ion adsorbent relative to the volume of the reticulated container can be 20%, 30%, 40%, 50%, 60%, 70%, 80%, or a value within a range formed by any two of the above values ​​as endpoints. Here, the filling rate of the alkali metal ion adsorbent relative to the volume of the reticulated container refers to the value (%) calculated as the ratio of the volume of the alkali metal ion adsorbent to the volume of the reticulated container.

[0083] In some embodiments of the present application, the alkali metal ions adsorbed by the alkali metal ion adsorbent are lithium ions. In some embodiments of the present application, the alkali metal ions adsorbed by the alkali metal ion adsorbent may also be sodium ions or lithium ions and sodium ions. In some embodiments of the present application, when the alkali metal ion with a small radius is a lithium ion, the adsorbed alkali metal ion is preferably a lithium ion, and when the alkali metal ion with a small radius is a sodium ion, the adsorbed alkali metal ion is preferably a sodium ion.

[0084] In some embodiments of the present application, there are no particular restrictions on the material of the mesh container, as long as it does not react with the components in the salt bath; it can be a stainless steel container, a metal container, etc., preferably made of SUS304, SUS316, etc., and preferably the metal is selected from titanium materials, etc. The present application does not particularly limit the specific structure of the mesh container, as long as it contains a mesh. The stainless steel container can be a stainless steel cage. The mesh container described in the present application can be a wire mesh container, a perforated metal container, a metal mesh container, etc., preferably a wire mesh container.

[0085] In some embodiments of the present application, the mesh size of the mesh container is greater than 0.15 mm, preferably greater than 0.18 mm, and more preferably greater than 0.20 mm.

[0086] In some embodiments of the present application, the shape of the alkali metal ion adsorbent filled in the mesh container is not particularly limited, and various shapes such as plates, rods, blocks, granules, agglomerates, flakes, and powders can be used. The size of the alkali metal ion adsorbent is also not particularly limited, and is controlled based on the mesh size of the actual mesh container to prevent it from flowing out of the mesh container and contaminating the salt bath.

[0087] In a fourth aspect, the present application provides the use of the ion sieve as described above, or the ion sieve prepared by the preparation method of the ion sieve as described above, or the composite salt bath additive as described above in salt bath purification.

[0088] The present application does not particularly limit the type of salt bath, as long as it contains lithium ions, wherein the impurity ions are mainly lithium ions; for example, it can be a salt bath containing NaNO3 in the presence of lithium ions, a salt bath containing KNO3, or a mixed salt bath containing NaNO3 and KNO3.

[0089] In a fifth aspect, the present application provides a method for using the ion sieve as described above or the ion sieve prepared by the preparation method of the ion sieve as described above, comprising:

[0090] Step 1): providing a salt bath to be purified, wherein the salt bath contains lithium ions; wherein the impurity ions are mainly lithium ions;

[0091] Step 2): adding the ion sieve to the salt bath to be purified;

[0092] Step 3): After the ion sieve has reacted in the salt bath to be purified for a certain period of time, the ion sieve is taken out.

[0093] In the method for using the ion sieve of the present application, in step 1), the concentration of the lithium ions is 50ppm-400ppm; preferably 50ppm-200ppm, more preferably 50ppm-100ppm. For example, the concentration of the lithium ions can be 50ppm, 60ppm, 70ppm, 80ppm, 90ppm, 100ppm, 120ppm, 140ppm, 150ppm, 160ppm, 170ppm, 180ppm, 190ppm, 200ppm, 250ppm, 300ppm, 350ppm, 400ppm or a value within the range formed by any two of the above values ​​as endpoints.

[0094] In the method for using the ion sieve of the present application, the salt bath in step 1) also contains sodium salt and / or potassium salt; preferably NaNO3 and / or KNO3. In some embodiments of the present application, the salt bath may contain a combination of NaNO3 and KNO3, or may be pure NaNO3 or pure KNO3. The combination of NaNO3 and KNO3 can be selected according to the desired application, and the concentrations of NaNO3 and KNO3 in the salt bath can be balanced according to the composition of the glass material undergoing ion exchange, thereby providing sufficient CS and DOL for the glass material; the glass material comprises lithium-containing glass-ceramics and lithium aluminosilicate glass; further, the crystalline phase of the lithium-containing glass-ceramics comprises one or more of petalite, lithium disilicate, lithium monosilicate, and eucryptite; it should be understood that, in the embodiments, any of the above ranges can be combined with any other ranges.

[0095] In the method for using the ion sieve of the present application, the temperature of the salt bath in step 1) is 350°C-550°C; preferably 380°C-530°C; more preferably 380°C-500°C. For example, the salt bath temperature can be 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, or a value within the range formed by any two of the above values ​​as endpoints.

[0096] In the method for using the ion sieve of the present application, the amount of the ion sieve added in step 2) is 0.50wt%-5.00wt% of the mass of the salt bath to be purified; preferably 1.00wt%-5.00wt% of the mass of the salt bath to be purified. For example, the amount of the ion sieve added can be 0.50wt%, 0.60wt%, 0.70wt%, 0.80wt%, 0.90wt%, 1.00wt%, 1.30wt%, 1.50wt%, 1.60wt%, 1.80wt%, 2.00wt%, 2.30wt%, 2.50wt%, 2.70wt%, 3.00wt%, 3.50wt%, 4.00wt%, 4.50wt%, 5.00wt% of the mass of the salt bath to be purified, or a value within a range formed by any two of the above values ​​as endpoints.

[0097] In the method for using the ion sieve of the present application, the reaction time of the ion sieve in the salt bath to be purified in step 3) is 3h-24h; preferably 6h-24h; more preferably 8h-16h. For example, the reaction time of the ion sieve in the salt bath to be purified can be 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 12h, 14h, 16h, 18h, 20h, 21h, 22h, 23h, 24h or a value within the range formed by any two of the above values ​​as endpoints.

[0098] In the method for using the ion sieve of the present application, when the lithium ion concentration of the salt bath to be purified is 50ppm-400ppm, the amount of ion sieve added is 0.50wt%-5.00wt% of the mass of the salt bath to be purified, and after the reaction time in the salt bath to be purified is 3h-24h, the absorption efficiency of the ion sieve is 50%-95%, preferably 53%-95%. For example, the absorption rate of the ion sieve can be 50%, 53%, 56%, 58%, 60%, 65%, 70%, 75%, 78%, 80%, 88%, 90%, 95% or a value within the range formed by any two of the above values ​​as endpoints.

[0099] In a sixth aspect, the present application provides a method for using the composite salt bath additive as described above, comprising:

[0100] Step 1): providing a salt bath to be purified, wherein the salt bath contains lithium ions;

[0101] Step 2): adding a composite salt bath additive to the salt bath to be purified;

[0102] Step 3): After the composite salt bath additive has reacted in the salt bath to be purified for a certain period of time, it is taken out.

[0103] In the method for using the composite salt bath additive of the present application, in step 1), the concentration of the lithium ions is 50ppm-400ppm; preferably 50ppm-200ppm, more preferably 50ppm-100ppm. For example, the concentration of the lithium ions can be 50ppm, 60ppm, 70ppm, 80ppm, 90ppm, 100ppm, 120ppm, 140ppm, 150ppm, 160ppm, 170ppm, 180ppm, 190ppm, 200ppm, 250ppm, 300ppm, 350ppm, 400ppm, or a value within the range formed by any two of the above values ​​as endpoints.

[0104] In the method for using the composite salt bath additive of the present application, the salt bath in step 1) further contains sodium salt and / or potassium salt; preferably NaNO3 and / or KNO3. In some embodiments of the present application, the salt bath may contain a combination of NaNO3 and KNO3, or may be pure NaNO3 or pure KNO3. The combination of NaNO3 and KNO3 can be selected according to the desired application, and the concentrations of NaNO3 and KNO3 in the salt bath can be balanced according to the composition of the glass material undergoing ion exchange, thereby providing the glass material with sufficient CS (surface compressive stress) and DOL (depth of compressive stress layer); the glass material comprises lithium-containing glass-ceramics and lithium aluminosilicate glass; further, the crystalline phase of the lithium-containing glass-ceramics comprises one or more of petalite, lithium disilicate, lithium monosilicate, and eucryptite; it should be understood that, in the embodiments, any of the above ranges can be combined with any other ranges.

[0105] In the method for using the composite salt bath additive of the present application, the temperature of the salt bath in step 1) is 350°C-550°C; preferably 380°C-530°C; more preferably 380°C-500°C. For example, the salt bath temperature can be 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, or a value within the range formed by any two of the above values ​​as endpoints.

[0106] In the method for using the composite salt bath additive of the present application, the amount of the alkali metal ion adsorbent added to the composite salt bath additive in step 2) is 0.5wt%-5.0wt% of the mass of the salt bath to be purified; preferably 1.00wt%-5.00wt% of the mass of the salt bath to be purified. For example, the amount of the alkali metal ion adsorbent added to the composite salt bath additive can be 0.50wt%, 0.60wt%, 0.70wt%, 0.80wt%, 0.90wt%, 1.00wt%, 1.30wt%, 1.50wt%, 1.60wt%, 1.80wt%, 2.00wt%, 2.30wt%, 2.50wt%, 2.70wt%, 3.00wt%, 3.50wt%, 4.00wt%, 4.50wt%, 5.00wt% of the mass of the salt bath to be purified, or a value within a range formed by any two of the above values ​​as endpoints.

[0107] In the method for using the composite salt bath additive of the present application, the reaction time of the composite salt bath additive in the salt bath to be purified in step 3) is 3h-24h; preferably 6h-24h; more preferably 8h-16h. For example, the reaction time of the composite salt bath additive in the salt bath to be purified can be 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 12h, 14h, 16h, 18h, 20h, 21h, 22h, 23h, 24h or a value within the range formed by any two of the above values ​​as endpoints.

[0108] In the method for using the composite salt bath additive of the present application, when the lithium ion concentration of the salt bath to be purified is 50ppm-400ppm, the amount of alkali metal ion adsorbent added to the composite salt bath additive is 0.50wt%-5.00wt% of the mass of the salt bath to be purified, and after the reaction time in the salt bath to be purified is 3h-24h, the absorption efficiency of the composite salt bath additive is 50%-95%, preferably 53%-95%. For example, the absorption rate of the composite salt bath additive can be 50%, 53%, 56%, 58%, 60%, 65%, 70%, 75%, 78%, 80%, 88%, 90%, 95% or a value within the range formed by any two of the above values ​​as endpoints.

[0109] In the seventh aspect, the present application also provides a chemical strengthening process for lithium-containing microcrystalline glass, which includes the following steps: adding the ion sieve described above in the present application or the ion sieve prepared by the above-mentioned ion sieve preparation method or the above-mentioned composite salt bath additive to the salt bath for chemically strengthening the lithium-containing microcrystalline glass.

[0110] Test method:

[0111] <Density Test>

[0112] The density of the ion sieve was tested using an electronic density balance SD-200L from ALFA MIRAGE in Japan. The test principle was the "Archimedes drainage method".

[0113] <Measurement of the lithium ion concentration in the salt bath>

[0114] An appropriate amount of molten salt bath to be measured for lithium ion concentration was taken out from the strengthening furnace. After the molten salt bath cooled, 0.25 g of the cooled solid substance was accurately weighed into a 100 mL glass beaker. After adding an appropriate amount of deionized water to dissolve it, it was filtered through a slow filter paper into a 100 mL volumetric flask. Then, 1 mL of 18 wt% hydrochloric acid aqueous solution was added to the volumetric flask. After adding deionized water to the volumetric flask to make up the volume and shaking well, the absorbance was measured using an atomic absorption spectrophotometer AA-6880, and then the lithium ion concentration in the salt bath was measured using the corresponding standard curve.

[0115] <Measurement of the lithium ion absorption rate of the ion sieve>

[0116] Step S1: In a clean stainless steel crucible, 700 g of potassium nitrate, 300 g of sodium nitrate and 1 g of lithium nitrate were mixed and melted at a temperature of 480 °C to prepare a salt bath with a lithium ion concentration of 100 ppm, and the concentration was denoted as C1;

[0117] Step S2: 50 mm × 50 mm × 0.7 mm ion sieve with a polished surface accounting for 1.00 wt% of the salt bath by mass was added to the mixed salt bath described in Step S1. After holding and reacting at 480 °C for 8 h, an appropriate amount of the salt bath was taken, and the lithium ion concentration was detected using the method in <Measurement of the lithium ion concentration in the salt bath>, denoted as C2;

[0118] The lithium ion absorption rate of the ion sieve = (C1 - C2) / C1 × 100%.

[0119] <XRD test>

[0120] The initial ion sieve and the ion sieve after reacting in a 480 °C salt bath with a lithium ion concentration of 100 ppm for 8 h were respectively ground into fine powders using a pulverizer, with a particle size less than 75 μm. Then, they were tested using an X-ray diffractometer to obtain XRD diffraction peak curves. The XRD diffraction data was analyzed using JADE software.

[0121] The X-ray diffractometer used in this application was Shimadzu XRD-6100. The range of the incident angle for testing was 2θ = 10 - 80°, the scanning speed was 6° / min, the working voltage was 40 KV, and the working current was 30 mA.

[0122] <Stability determination>

[0123] The crystal form of the ion sieve after absorbing lithium ions for 8 hours in a 480°C salt bath with a lithium ion concentration of 100 ppm is compared with the crystal form before absorbing lithium ions. If obvious changes occur, the ion sieve is considered unstable; otherwise, the ion sieve is considered stable.

[0124] <Test of crystal content in ion sieve>

[0125] The crystal content in the ion sieve is measured by the ratio of the crystal phase peak area in the XRD spectra of the initial ion sieve and the ion sieve after absorbing lithium ions in the salt bath, that is, the ratio of the crystal phase peak area based on the XRD spectrum fitting to the total peak area of ​​the fitting is the crystal content.

[0126] In the present invention, an X-ray diffractometer is used to test the initial ion sieve and the ion sieve after absorbing lithium ions in a salt bath, and the X-ray diffractometer test result file (RAW format) is imported into X-ray diffraction data Rietveld refinement software (such as Jade) for fitting and calculation.

[0127] <Determination of the status of fallen fragments>

[0128] A polished ion sieve measuring 50 mm x 50 mm x 0.7 mm was added to the salt bath to be purified. The amount of plate-shaped ion sieve added was 1.0 wt% of the salt bath mass. The salt bath consisted of 700 g of KNO₃, 300 g of NaNO₃, and 1 g of LiNO₃, with a lithium ion concentration of 100 ppm. The reaction was continued at 480°C for 8 hours before removal. The ion sieve was observed after purification in the salt bath. If no fragments were detached, the fragmented state was recorded as "no fragments were detached." If fragments were detached, the size of the fragments was measured.

[0129] Method for measuring the size of detached fragments: collect the detached fragments generated by the ion sieve, weigh them and record them as W1, sieve them with a 100-mesh sieve, and the weight of the sieve residue is recorded as W2. If W2 / W1=100%, it indicates that the size of the fragments detached from the above ion sieve is greater than 0.15mm, and the detached fragment size is recorded as greater than 0.15mm; if W2 / W1 is less than 100%, it indicates that the size of the fragments detached from the above ion sieve is less than 0.15mm, and the detached fragment size is recorded as less than 0.15mm.

[0130] <Appearance test>

[0131] The selected microcrystalline glass sheet was cleaned and dried, the sample was placed on a stage, and photographed using a Canon entry-level digital camera to obtain the appearance of the glass sheet surface.

[0132] <Pianguan Microscope Test>

[0133] The selected glass-ceramic sheets were ultrasonically cleaned and dried, and the samples were placed on a stage and photographed using an AxioLab 5 polarizing microscope to obtain a surface polarizing microscope image of the glass sheet surface.

[0134] The present application is described below by means of specific embodiments:

[0135] Example 1

[0136] The raw materials were accurately weighed according to the following proportions: SiO2 57.0 mol%, Al2O3 3.0 mol%, and Na2O 40.0 mol%; the total mass of the raw materials was 1 kg, and then melted at 1450°C for 5 hours to form a glass liquid.

[0137] The glass liquid was injected into a mold for molding, annealed at 420° C. for 12 h, and then cut and polished to obtain an ion sieve with a size of 50 mm×50 mm×0.7 mm and a polished surface.

[0138] The plate-like ion sieves obtained above were subjected to density tests respectively; then the plate-like ion sieves were added to a salt bath to be purified, the amount of the plate-like ion sieve added being 1.0 wt% of the mass of the salt bath to be purified, the salt bath being a salt bath of 700 g KNO3, 300 g NaNO3 and 1 g LiNO3, and the lithium ion concentration being 100 ppm; after reacting at 480°C for 8 hours, the ion sieves were taken out; the lithium ion absorption rate of the ion sieves was tested, and the stability and the state of the shedding fragments were determined, and the crystal content was tested; the results are shown in Table 1-2.

[0139] Example 2-11

[0140] Except for adjusting the raw material ratio as shown in Table 1, the rest is the same as Example 1.

[0141] Comparative Examples 1-6

[0142] Except for adjusting the raw material ratio as shown in Table 2, the rest is the same as Example 1.

[0143] Comparative Example 7

[0144] The process is the same as in Example 1 except that the temperature for absorbing lithium ions in the salt bath is 565°C.

[0145] In addition, a lithium aluminum silicate substrate glass having a composition of SiO2 70 mol%, Al2O3 4.15 mol%, Li2O 20.68%, P2O5 1.02%, ZrO2 2.66%, Na2O 0.29%, K2O 0.09%, CaO 0.80 mol%, and B2O3 0.31 mol% was placed in a mixed salt bath of 70 wt% NaNO3 and 30 wt% KNO3 at 480°C, and the ion sieves of Example 2 and Comparative Example 4 were respectively added at an amount of 1 wt% of the mass of the mixed salt bath. After chemical strengthening treatment for 8 hours, the surface appearance of the chemically strengthened glass obtained after chemical strengthening treatment was observed using a polarizing microscope. The obtained surface appearance images are shown in Figures 9-10.

[0146] Furthermore, the ion sieves from Example 4 were placed in 316 stainless steel cages A (260 mm long, 110 mm wide, 50 mm high) with different mesh sizes to form composite salt bath additives A1-A4. These were then added to the salt bath to be purified and reacted at 480°C for 8 hours. The lithium ion absorption rate of the ion sieves was then tested. The mesh sizes of the 316 stainless steel cages A were 20, 80, 100, and 120 mesh, respectively. The salt bath contained 700 g of KNO₃, 300 g of NaNO₃, and 1 g of LiNO₃, with a lithium ion concentration of 100 ppm. The ion sieves from Example 4 had a filling rate of 30% relative to the volume of the 316 stainless steel cages A, and the amount added was 0.8 wt% of the mass of the salt bath to be purified. The results are shown in Table 3.

[0147] The ion sieves from Example 7 were placed in 316 stainless steel cages B (100 mm long, 100 mm wide, 20 mm high) with different mesh sizes to form composite salt bath additives B1-B4. These were then added to the salt bath to be purified and reacted at 480°C for 8 hours. The lithium ion absorption rate of the ion sieves was then tested. The mesh sizes of the 316 stainless steel cages B were 20, 80, 100, and 120 mesh, respectively. The salt bath contained 700 g of KNO₃, 300 g of NaNO₃, and 1 g of LiNO₃, with a lithium ion concentration of 100 ppm. The ion sieves from Example 7 had a filling rate of 40% relative to the volume of the 316 stainless steel cages B, and the amount added was 1.0 wt% of the mass of the salt bath to be purified. The results are shown in Table 4.

[0148] In addition, a lithium aluminum silicate substrate glass having a composition of SiO2 70 mol%, Al2O3 4.15 mol%, Li2O 20.68%, P2O5 1.02%, ZrO2 2.66%, Na2O 0.29%, K2O 0.09%, CaO 0.80 mol%, and B2O3 0.31 mol% was placed in a mixed salt bath of 70 wt% NaNO3 and 30 wt% KNO3 at 480°C, and composite salt bath additive A3 or composite salt bath additive B3 was added, respectively, wherein the amount of ion sieve added to composite salt bath additive A3 or composite salt bath additive B3 was 1.2 wt% of the mass of the mixed salt bath. After chemical strengthening treatment for 8 hours, the surface appearance of the chemically strengthened glass obtained after chemical strengthening treatment was observed using a polarizing microscope. The obtained surface appearance images are shown in Figures 11-12.

[0149] Table 1. Composition and related performance parameters of the ion sieves of Examples 1-11

[0150] Table 2. Composition and related performance parameters of the ion sieves in Comparative Examples 1-7

[0151] Table 3. Composite salt bath additives and their lithium ion absorption rates

[0152] Table 4. Composite salt bath additives and their lithium ion absorption rates

[0153] (1) The ion sieves prepared in the examples of the present application had a crystal content of less than 10 wt% before and after absorbing lithium ions, with no crystal transformation. The composition and structure of the ion sieves were stable, no fragments were shed, and they had high lithium ion absorption efficiency. Comparative Examples 1-6, which were prepared outside the formulation of the present application, showed significant changes in crystal content before and after absorbing lithium ions, resulting in crystal transformation, as shown in Figures 1 and 2.

[0154] (2) FIG3 is a diagram showing the appearance of the ion sieve in Example 1 after absorbing lithium ions in a salt bath at 480°C for 8 hours; FIG4 is a diagram showing the appearance of the ion sieve in Example 6 after absorbing lithium ions in a salt bath at 480°C for 8 hours; FIG5 is a diagram showing the appearance of the ion sieve in Comparative Example 2 after absorbing lithium ions in a salt bath at 480°C for 8 hours; FIG6 is a diagram showing the appearance of the ion sieve in Comparative Example 3 after absorbing lithium ions in a salt bath at 480°C for 8 hours; FIG7 is a diagram showing the appearance of the ion sieve in Comparative Example 5 after absorbing lithium ions in a salt bath at 480°C for 8 hours; FIG8 is a diagram showing the appearance of the ion sieve in Comparative Example 6 after absorbing lithium ions in a salt bath at 480°C for 8 hours. FIG9 is a polarizing micrograph of the surface of the chemically strengthened glass obtained by adding the ion sieve of Example 2 to the salt bath; FIG10 is a polarizing micrograph of the surface of the chemically strengthened glass obtained by adding the ion sieve of Comparative Example 4 to the salt bath. As can be seen from FIG9 , no detached fragments of the ion sieve are attached to the surface of the chemically strengthened glass; while as can be seen from FIG10 , a relatively large amount of detached fragments of the ion sieve are attached to the surface of the chemically strengthened glass.

[0155] (3) As can be seen from Tables 3-4, when the ion sieve is placed in a 316 stainless steel cage with a mesh size of 100 mesh or less, i.e., a mesh size of 0.15 mm or more, for salt bath purification, the mesh size of the 316 stainless steel cage has little effect on the lithium ion absorption rate of the ion sieve, and basically does not affect the actual effect of the ion sieve on salt bath purification; and it has a high lithium ion adsorption efficiency. Figure 11 is a surface polarizing micrograph of the chemically strengthened glass obtained after adding the composite salt bath additive A3 to the salt bath; Figure 12 is a surface polarizing micrograph of the chemically strengthened glass obtained after adding the composite salt bath additive B3 to the salt bath. As can be seen from Figures 11-12, there are no detached fragments of the ion sieve attached to the surface of the chemically strengthened glass.

[0156] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit the technical solutions. Those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present application that do not depart from the purpose and scope of the technical solutions of the present application should be included in the scope of the claims of the present application.

Claims

1. An ion sieve, characterized in that, In terms of molar percentage of oxides, the ion sieve comprises the following components: SiO2 45.0 - 64.0 mol%; Al2O3 2.0 - 16.0 mol%; Na2O 34.0 - 45.0 mol%; ZrO2 0 - 3.0 mol%; Y2O3 0 - 2.0 mol%; Among them, after the ion sieve undergoes lithium ion absorption for 0.5 h - 24 h in a salt bath at a temperature of 350°C - 550°C, the crystal form of the ion sieve does not change.

2. The ion sieve according to claim 1, wherein After any proportion of sodium-lithium ion exchange occurs within the range of 350°C - 550°C for the ion sieve, the content of crystals in the ion sieve is less than 10 wt%.

3. The ion sieve according to claim 1, wherein The density of the ion sieve is 2.40 g / cm 3 - 2.55 g / cm 3 .

4. The ion sieve according to claim 1, characterized in that, After the ion sieve undergoes lithium ion absorption for 0.5 h - 24 h in a 350°C - 550°C salt bath, no fragments fall off.

5. The ion sieve according to any one of claims 1-4, characterized in that, The concentration of lithium ions in the salt bath is 50 ppm - 400 ppm.

6. The preparation method of the ion sieve according to any one of claims 1-5, characterized in that, Including: Select raw material components according to the composition of the ion sieve for mixing, and after melting and shaping, through annealing treatment, an ion sieve is obtained.

7. The preparation method according to claim 6, characterized in that, The melting temperature is 1300°C - 1650°C, and the melting time is 1 h - 24 h; Preferably, the annealing temperature is 400°C - 450°C, and the annealing time is 12 h - 24 h.

8. A composite salt bath additive, the composite salt bath additive is a mesh container and an alkali metal ion adsorbent filled in the mesh container, the alkali metal ion adsorbent is the ion sieve according to any one of claims 1 - 5 or the ion sieve prepared by the preparation method of the ion sieve according to any one of claims 6 - 7; the mesh size of the mesh container is more than 0.15 mm.

9. The composite salt bath additive according to claim 8, characterized in that, The mesh container is at least one of a stainless steel container and a metal container.

10. The composite salt bath additive according to claim 8, wherein, Relative to the volume of the mesh container, the filling rate of the alkali metal ion adsorbent is 20% - 80%.

11. The application of the ion sieve according to any one of claims 1 - 5 or the ion sieve prepared by the preparation method of the ion sieve according to any one of claims 6 - 7 or the composite salt bath additive according to any one of claims 8 - 9 in salt bath purification.

12. The method for using the composite salt bath additive according to any one of claims 8-10, characterized in that, Including steps: Provide a salt bath to be purified, and the salt bath contains lithium ions; Add the composite salt bath additive to the salt bath to be purified; Take out the composite salt bath additive after it reacts in the salt bath to be purified for a certain time; Preferably, the addition amount of the alkali metal ion adsorbent in the composite salt bath additive is 0.5 wt% - 5.0 wt% of the mass of the salt bath to be purified; Preferably, the temperature of the salt bath is 350°C - 550°C; Preferably, the concentration of lithium ions in the salt bath is 50 ppm - 400 ppm; Preferably, the reaction time of the composite salt bath additive in the salt bath to be purified is 3 h - 24 h; Preferably, when the lithium ion concentration of the salt bath to be purified is 50 ppm - 400 ppm, the addition amount of the alkali metal ion adsorbent is 0.50 wt% - 5.00 wt% of the mass of the salt bath to be purified, and with respect to the volume of the net container, the filling rate of the alkali metal ion adsorbent is 20% - 80%; the reaction time of the composite salt bath additive in the salt bath to be purified is 3 h - 24 h, and the absorption efficiency of the composite salt bath additive is 50% - 95%.

Images