Ceramic tile surface coating material, preparation method and application

Abstract

The present application relates to the technical field of ceramic tile processing, and particularly relates to a ceramic tile surface coating material, a preparation method and application. The coating material is prepared from modified lithium tailing composite powder, zinc-aluminum-boron-silicon fused block, albite, nepheline syenite, calcined kaolin, calcined alumina, wollastonite, calcined talc and dolomite and the like. The modified lithium tailing composite powder is prepared by interfacial modification of low-iron refined lithium tailing powder with phytic acid, zirconium ammonium carbonate, dihydroxy bis(ammonium lactate) titanium(IV), calcium lactate, ammonium pentaborate and polyacrylammonium crystallization inducers and heat treatment. The coating material can improve the whiteness and gloss of the glaze layer, reduce the yellowing tendency, reduce pinhole and cave defects, and realize high-value utilization of lithium tailings in ceramic tile surface decoration.

Description

Technical Field

[0001] This invention relates to the field of ceramic tile processing technology, specifically to a ceramic tile surface coating material, its preparation method, and its application. Background Technology

[0002] The surface coating material of ceramic tiles is a crucial factor affecting their decorative effect and surface quality. Existing ceramic tile glazes or surface coatings typically use feldspar, kaolin, quartz, alumina, frit, zirconium silicate, or titanium-based opacifiers as main raw materials. Whiteness, gloss, and a smooth glaze surface are achieved by adjusting the glaze's melting properties and opacification crystallization effect. However, traditional zirconium white raw materials are expensive, and ordinary titanium sources are prone to yellowing. Furthermore, directly adding tailings-like solid waste as ordinary silica-alumina raw materials to the glaze system often results in insufficient whiteness, dark spots, pinholes, cavities, and an uneven glaze surface due to iron impurities, insufficient particle activity, and uneven distribution of crystallized components. Therefore, developing a ceramic tile surface coating material that can utilize lithium tailings solid waste while achieving high whiteness, low yellowing, and low defects is of great significance.

[0003] Chinese invention patent CN110128016A discloses a zirconium-free ultra-white glaze and its preparation method. It uses raw materials such as quartz, calcined talc, washed kaolin, calcined kaolin, potassium feldspar, sodium feldspar, lithium porcelain stone, nepheline, dolomite, alumina, titanium dioxide frit, and zinc oxide. By removing zirconium compounds and adjusting the glaze formula, it aims to reduce costs and radiation. This invention can address the high cost of traditional zirconium white glazes to some extent. However, it primarily relies on adjusting the formula using conventional glaze mineral raw materials and titanium dioxide frit. It does not involve using lithium tailings as a functional composite powder for interface modification, nor does it address the problems of decreased whiteness, yellowing, and pinholes / cavities that easily occur when tailings are directly added.

[0004] Chinese invention patent CN104909570A discloses an opacifier, its preparation method, and a ceramic glaze containing the opacifier. It uses calcium carbonate and crystalline titanium dioxide as the main components to form a stable titanium sphene crystal structure in the ceramic glaze, thus avoiding the yellowing problem caused by directly adding titanium dioxide particles. This invention demonstrates that the synergistic effect of calcium and titanium sources in improving the yellowing problem of titanium-based opacifiers is significant. However, it uses an independently prepared calcium carbonate-titanium dioxide opacifier, rather than anchoring the calcium and titanium components to the surface of lithium tailings particles as water-soluble precursors. Furthermore, it does not address the issue of high-value utilization of lithium tailings in ceramic tile surface coating materials.

[0005] Chinese invention patent CN113860728A discloses a SiO2-CaCO3-TiO2 composite ceramic emulsion based on ordered interfacial bonding and its preparation method. The method involves first modifying SiO2, CaCO3, and TiO2 powders, then mixing, adjusting pH, heating and stirring, and calcining at low temperature to obtain the composite ceramic emulsion. While this invention improves the emulsification effect through interfacial bonding between powders, it still relies on externally added SiO2, CaCO3, and TiO2 powders to construct the composite emulsion. It does not utilize the silicon and aluminum components of lithium tailings themselves as the main carrier, nor does it combine phytic acid complexation and anchoring, ammonium pentaborate melting adjustment, and zinc-aluminum-boron-silicon frit to regulate glaze melting and spreading to simultaneously address issues of whiteness, yellowing, smoothness, and pinhole defects.

[0006] Therefore, although existing technologies disclose zirconium-free ultra-white glazes, perovskite-based opacifiers, and SiO2-CaCO3-TiO2 composite opacifiers, they still suffer from problems such as limited utilization of solid waste, insufficient control of whiteness and defects when lithium tailings are directly added to the glaze, easy yellowing when titanium sources are used alone, and difficulty in uniformly distributing crystallization components on the surface of tailings particles. Based on this, it is necessary to provide a ceramic tile surface coating material, its preparation method, and its application. Summary of the Invention

[0007] To address the shortcomings of the existing technology, this invention provides a ceramic tile surface coating material, its preparation method, and its application.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A ceramic tile surface coating material is composed of the following raw materials: modified lithium tailings composite powder, zinc-aluminum-borosilicate frit, sodium feldspar, nepheline syenite, calcined kaolin, calcined alumina, wollastonite, calcined talc, and dolomite. The modified lithium tailings composite powder is prepared by a method including the following steps: lithium tailings are subjected to magnetic separation to remove iron to obtain low-iron lithium tailings powder, which is then mixed with a crystallization inducer for interface modification treatment, and then heat-treated at 500-650℃. The crystallization inducing agent comprises phytic acid, zirconium ammonium carbonate, dihydroxybis(ammonium lactate)titanium(IV), and calcium lactate.

[0009] Preferably, the crystallization inducing agent further comprises ammonium borate and ammonium polyacrylate; based on 100 parts by weight of the low-iron lithium tailings powder, the crystallization inducing agent comprises: 2-5 parts of 50wt% phytic acid aqueous solution, 5-10 parts of 20% zirconium carbonate ammonium solution (calculated as ZrO2), 15-22 parts of crystallization component, 0.5-1.5 parts of ammonium pentaborate, and 0.1-0.5 parts of ammonium polyacrylate; the crystallization component is composed of ammonium titanate lactate aqueous solution and calcium lactate pentahydrate in a mass ratio of 1:(1.8-2.2); Preferably, the aqueous solution of titanium lactate is an aqueous solution of dihydroxybis(ammonium lactate)titanium(IV).

[0010] Preferably, the heat treatment temperature is 520-600℃ and the holding time is 30-90min.

[0011] Preferably, the zinc-aluminum-boron-silicon frit comprises, by mass percentage: 45-55% SiO2, 12-18% B2O3, 8-14% Al2O3, 8-15% ZnO, 4-8% Na2O+K2O, and 2-6% CaO, with a softening temperature of 680-760℃.

[0012] Preferably, the conditions for the interface modification treatment are: pH 7.5-9.0, temperature 50-70℃, and time 30-90min.

[0013] Preferably, the mixture comprises 30-70 parts of modified lithium tailings composite powder, 2-8 parts of zinc-aluminum-boron-silicon frit, 3-12 parts of sodium feldspar, 2-10 parts of nepheline syenite, 8-18 parts of calcined kaolin, 2-10 parts of calcined alumina, 2-8 parts of wollastonite, 1-5 parts of calcined talc, 1-5 parts of dolomite, and 30-50 parts of water.

[0014] Preferably, the ceramic tile surface coating material further comprises: 0.1-0.8 parts of sodium carboxymethyl cellulose and 0.1-0.6 parts of sodium tripolyphosphate.

[0015] Preferably, the Fe2O3 content in the low-iron lithium tailings powder is not higher than 0.75%, the residue on a 325-mesh sieve is less than 0.5%, and the D90 is less than 22μm.

[0016] The method for preparing the ceramic tile surface coating material includes: mixing the raw materials, wet ball milling, sieving, adjusting the specific gravity to 1.75-1.85 g / cm³ and the flow rate to 40-50 s, and aging the mixture to obtain the final product.

[0017] The method for applying the ceramic tile surface coating material in ceramic tile surface decoration is characterized by comprising: applying the lithium tailings-based ceramic tile surface coating material to the surface of the ceramic tile body by bell glazing, with a dry glaze application amount of 200-250 g / m²; drying at 90-110℃ for 10-25 min after glazing, and then firing in a roller kiln at a maximum firing temperature of 1100-1250℃ for 5-12 min, and obtaining a ceramic tile with a surface coating after cooling.

[0018] Existing ceramic tile surface coating materials typically rely on feldspar, frit, zirconium silicate, or titanium-based opacifiers to achieve whiteness and glaze decoration effects. However, higher zirconium silicate content leads to higher costs, and ordinary solid waste raw materials are difficult to directly replace traditional glaze raw materials. If lithium tailings are directly added to ceramic tile surface coating materials, due to their iron impurities, insufficient particle surface activity, and uneven distribution of crystallized components, it is easy to cause insufficient whiteness, yellowing, dark spots, pinholes, cavities, and reduced glaze smoothness.

[0019] This invention does not directly add lithium tailings as ordinary filler to the glaze. Instead, it first reduces the impact of iron impurities in lithium tailings on the whiteness and dark spots of the glaze by removing iron through magnetic separation and refining treatment. Then, it uses a crystallization inducer to perform interface modification on the low-iron refined lithium tailings powder, so that the lithium tailings are transformed from ordinary siliceous aluminous raw materials into functional composite powders with interface crystallization induction effect. Among them, dihydroxybis(ammonium lactate)titanium(IV) aqueous solution and calcium lactate pentahydrate constitute the calcium-titanium lactate complex crystallization component. Dihydroxybis(ammonium lactate)titanium(IV) provides the titanium source, and calcium lactate pentahydrate provides the calcium source. The two work together as water-soluble precursors, which can be more uniformly distributed on the surface of lithium tailings particles than directly adding TiO2 powder and calcium carbonate powder. During the firing process, the calcium and titanium components can react synergistically with SiO2 in lithium tailings to induce the formation of fine and dispersed calcium-titanium-silicon opaque crystallization phase, thereby improving the light scattering ability and whiteness of the glaze layer, and reducing the problem of yellowing caused by the formation of free titanium oxide crystal phase by a single titanium source. Phytic acid aqueous solution possesses a polyphosphate complex structure, which can complex, anchor, and stabilize the zirconium, titanium, and calcium components, allowing the crystallization-inducing components to be more uniformly fixed on the surface of lithium tailings particles. Zirconium ammonium carbonate provides auxiliary emulsification and interface stabilization, further improving the uniformity of emulsification crystallization centers in conjunction with phytic acid. Ammonium pentaborate is used to regulate glaze melting and venting windows, enabling the glaze to both expel gas during firing and form a continuous and smooth glassy phase in the later stages. Ammonium polyacrylate improves the dispersion stability of the crystallization inducer in the aqueous system, reducing uneven crystallization caused by local agglomeration. After low-temperature heat treatment, the composite interface modification layer is pre-fixed on the surface of lithium tailings particles, reducing the risk of concentrated venting during subsequent firing and improving the stability of the modified lithium tailings composite powder in the glaze system.

[0020] Through the above technical solution, this invention can reduce reliance on traditional zirconium white raw materials while achieving high-value utilization of lithium tailings solid waste in ceramic tile surface coating materials. The modified lithium tailings composite powder, in synergy with components such as zinc-aluminum-borosilicate frit, wollastonite, calcined talc, and dolomite, can improve the glaze's opacity whitening, melting and spreading, and degassing processes. This results in a ceramic tile surface coating with higher whiteness, lower yellowing tendency, higher gloss, lower surface roughness, and fewer pinholes and cavities, thus obtaining a smoother, whiter ceramic tile glaze with fewer appearance defects.

[0021] The beneficial effects of this invention are: 1. This invention provides a ceramic tile surface coating material, its preparation method, and its application. Modified lithium tailings composite powder is prepared by refining lithium tailings powder with low-iron and interfacial modification with a crystallization inducing agent. This transforms lithium tailings from being directly added to glazes as ordinary silica-alumina fillers into a functional composite powder with interfacial crystallization inducing properties. This method can reduce the impact of iron impurities in lithium tailings on the whiteness and dark spots of the glaze and improve the utilization value of lithium tailings in ceramic tile surface coating materials.

[0022] 2. This invention employs a calcium-titanium lactate composite crystallization component composed of an aqueous solution of dihydroxybis(ammonium lactate)titanium(IV) and calcium lactate pentahydrate, combined with an aqueous solution of phytic acid and an aqueous solution of zirconium ammonium carbonate, to allow the titanium, calcium, zirconium, and other crystallization components to be more uniformly anchored on the surface of lithium tailings particles. During firing, this composite interface modification layer can synergistically interact with components such as SiO2 in the lithium tailings to induce the formation of fine and dispersed calcium-titanium silicon-like opaque crystallization phases, thereby improving the whiteness of the glaze and reducing the yellowing problem that is easily caused by adding titanium sources alone.

[0023] 3. This invention regulates the melting, venting, and spreading processes of the glaze layer using ammonium pentaborate and zinc-aluminum-borosilicate frit, enabling the glaze layer to fully expel gases during firing and form a continuous, smooth glassy phase in the later stages. Therefore, the ceramic tile surface coating material obtained by this invention exhibits high whiteness, low yellowing tendency, high gloss, low surface roughness, and fewer pinholes and cavities. Simultaneously, it reduces reliance on traditional zirconium white raw materials and possesses significant value for solid waste resource utilization. Detailed Implementation

[0024] The invention will now be described in further detail with reference to specific embodiments, but it should not be construed as limiting the scope of the invention to the following embodiments.

[0025] The raw materials described in this application are partially described; all other raw materials not described are commercially available. Sodium carboxymethyl cellulose was purchased from Hubei GREAT Biomedical Technology Co., Ltd., model number GREAT0514.

[0026] Sodium tripolyphosphate was purchased from Jiangsu Maige Biotechnology Co., Ltd., model number 238503-500G.

[0027] Ammonium polyacrylate was purchased from Guangdong Fangxin Biotechnology Co., Ltd., with a molecular weight of 30 million g / mol.

[0028] The dihydroxybis(ammonium lactate)titanium(IV) aqueous solution was purchased from Guangdong Yuanfeng Chemical Reagent Co., Ltd., with an active ingredient content of 50%.

[0029] Example 1

[0030] A ceramic tile surface coating material is prepared from the following raw materials in parts by weight: 52 parts modified lithium tailings composite powder, 8 parts sodium feldspar, 6 parts nepheline syenite, 12 parts calcined kaolin, 6 parts calcined alumina, 5 parts wollastonite, 3 parts calcined talc, 2 parts dolomite, 4 parts zinc-aluminum-boron-silicon frit, 0.25 parts sodium carboxymethyl cellulose, 0.35 parts sodium tripolyphosphate, and 42 parts water.

[0031] The zinc-aluminum-boron-silicon frit comprises, by mass percentage: 50% SiO2, 15% B2O3, 12% Al2O3, 12% ZnO, 6% Na2O+K2O, and 5% CaO, with a softening temperature of 720℃ and a residue of less than 0.5% on a 325-mesh sieve.

[0032] The lithium tailings powder comprises, by mass percentage: 78.2% SiO2, 13.1% Al2O3, 0.32% CaO, 0.36% MgO, 0.72% Fe2O3, 2.20% K2O, and 5.10% Na2O; the D50 of the lithium tailings powder is 6.5-8.5 μm, and the D90 is less than 22 μm.

[0033] The preparation method of the modified lithium tailings composite powder is as follows: S1. The lithium tailings raw material is dried, crushed, magnetically separated to remove iron, and ball-milled to obtain low-iron refined lithium tailings powder; the low-iron refined lithium tailings powder has an Fe2O3 content of no more than 0.75%, a 325-mesh sieve residue of less than 0.5%, and a D90 of less than 22μm. S2. Disperse 100 parts by weight of low-iron refined lithium tailings powder in 150 parts by weight of water, add a crystallization inducing agent, stir at 60°C for 45 min, and adjust the pH of the system to 8.2 with 1 mol / L ammonia water to obtain a compound interface-modified lithium tailings slurry; the crystallization inducing agent includes the following components: 3.6 parts by weight of 50 wt% phytic acid aqueous solution, 7.5 parts by weight of 20% zirconium carbonate ammonium aqueous solution (calculated as ZrO2), 18 parts by weight of crystallization component, 0.8 parts by weight of ammonium pentaborate, and 0.25 parts by weight of ammonium polyacrylate; wherein, the crystallization component is composed of dihydroxybis(ammonium lactate)titanium(IV) aqueous solution and calcium lactate pentahydrate in a mass ratio of 1:2; the dihydroxybis(ammonium lactate)titanium(IV) solution has a mass fraction of 50% based on TiO2; S3. The compound interface-modified lithium tailings slurry is dried at 105℃ until the moisture content is less than 1.0%, then kept at 560℃ for 45 minutes, cooled and crushed to obtain modified lithium tailings composite powder.

[0034] The preparation method of the surface coating material of the ceramic tile is as follows: Modified lithium tailings composite powder, albite, nepheline syenite, calcined kaolin, calcined alumina, wollastonite, calcined talc, dolomite, and zinc-aluminum-borosilicate frit are weighed according to the above-mentioned weight proportions. Sodium carboxymethyl cellulose, sodium tripolyphosphate, and water are added. The mixture is wet-milled for 6 hours according to the raw material:ball stone:water mass ratio of 1:1.8:0.42 to obtain a mixed glaze slurry. The mixed glaze slurry is filtered, and the specific gravity of the glaze slurry is adjusted to 1.80 g / cm³. 3 The flow rate was measured to be 45s using a 100mL flow rate cup, and the material was aged for 16 hours to obtain the surface coating material for ceramic tiles.

[0035] Example 2

[0036] The method is basically the same as in Example 1, except that the surface coating material of the ceramic brick is prepared from the following raw materials in parts by weight: 45 parts modified lithium tailings composite powder, 10 parts albite, 7 parts nepheline syenite, 13 parts calcined kaolin, 7 parts calcined alumina, 6 parts wollastonite, 2 parts calcined talc, 3 parts dolomite, 5 parts zinc-aluminum-boron-silicon frit, 0.25 parts sodium carboxymethyl cellulose, 0.35 parts sodium tripolyphosphate, and 40 parts water; the rest of the preparation method is the same as in Example 1.

[0037] Example 3

[0038] The method is basically the same as in Example 1, except that the surface coating material of the ceramic brick is prepared from the following raw materials in parts by weight: 60 parts modified lithium tailings composite powder, 6 parts sodium feldspar, 5 parts nepheline syenite, 11 parts calcined kaolin, 5 parts calcined alumina, 4 parts wollastonite, 4 parts calcined talc, 2 parts dolomite, 3 parts zinc-aluminum-boron-silicon frit, 0.25 parts sodium carboxymethyl cellulose, 0.35 parts sodium tripolyphosphate, and 44 parts water; the rest of the preparation method is the same as in Example 1.

[0039] Example 4

[0040] The process is basically the same as in Example 1, except that: in the crystallization inducing agent, the calcium titanate complex crystallization component is 15 parts by weight, which is composed of 5 parts by weight of a 50% by weight aqueous solution of dihydroxybis(ammonium lactate)titanium(IV) based on TiO2 and 10 parts by weight of calcium lactate pentahydrate.

[0041] Example 5

[0042] The process is basically the same as in Example 1, except that: in the crystallization inducing agent, the calcium titanate complex crystallization component is 21 parts by weight, which is composed of 7 parts by weight of a 50% by weight aqueous solution of dihydroxybis(ammonium lactate)titanium(IV) based on TiO2 and 14 parts by weight of calcium lactate pentahydrate.

[0043] Comparative Example 1

[0044] The process is basically the same as in Example 1, except that the modified lithium tailings composite powder in Example 1 is replaced with an equal amount of unmodified lithium tailings powder; the unmodified lithium tailings powder is only dried, crushed and ball-milled, without magnetic separation to remove iron, crystallization inducer interface modification and 560°C heat treatment.

[0045] Comparative Example 2

[0046] The process is basically the same as in Example 1, except that no crystallizing components are added to the crystallization inducing agent, that is, no aqueous solution of dihydroxybis(ammonium lactate)titanium(IV) and calcium lactate pentahydrate are added, while the remaining components and preparation steps remain unchanged.

[0047] Comparative Example 3

[0048] The process is basically the same as in Example 1, except that: calcium lactate pentahydrate is not added to the crystallization inducer, but only 18 parts by weight of a 50% (by mass) aqueous solution of dihydroxybis(ammonium lactate)titanium(IV) based on TiO2 is added, while the other components and preparation steps remain unchanged.

[0049] Comparative Example 4

[0050] The process is basically the same as in Example 1, except that: no aqueous solution of dihydroxybis(ammonium lactate)titanium(IV) is added to the crystallization inducing agent, only 18 parts by weight of calcium lactate pentahydrate is added, and the remaining components and preparation steps remain unchanged.

[0051] Comparative Example 5

[0052] The process is basically the same as in Example 1, except that: instead of using calcium titanium lactate compound crystallization components, 2.88 parts by weight of TiO2 powder and 3.89 parts by weight of calcium carbonate powder are added to the crystallization inducing agent so that the equivalent amounts of TiO2 and CaO are basically consistent with the aqueous solution of dihydroxybis(ammonium lactate)titanium(IV) and calcium lactate pentahydrate in Example 1.

[0053] Comparative Example 6

[0054] The process is basically the same as in Example 1, except that 50wt% phytic acid aqueous solution is not added to the crystallization inducer, while the other components and preparation steps remain unchanged.

[0055] Comparative Example 7

[0056] It is basically the same as Example 1, except that: ammonium pentaborate is not added to the crystallization inducer, and the other components and preparation steps remain unchanged.

[0057] Comparative Example 8

[0058] The process is basically the same as in Example 1, except that zinc-aluminum-borosilicate frit is not added to the surface coating material of the ceramic tile, and an equal amount of sodium feldspar is used instead.

[0059] Test Example 1

[0060] The ceramic tile surface coating materials prepared in Examples 1-5 and Comparative Examples 1-8 were applied to the surface of ceramic tile blanks of the same batch using a bell-jar glazing method, with a dry glaze application amount of 225 g / m². After glazing, the blanks were dried at 100°C for 15 min, and then fired in a roller kiln at a maximum firing temperature of 1185°C for 8 min, with a total firing cycle of 58 min. After cooling, the ceramic tile samples to be tested were obtained. Five samples were prepared for each group, and the average value of the test results was taken.

[0061] 1. Whiteness test The test was conducted in accordance with GB / T 5950-2008 "Method for Measurement of Whiteness of Building Materials and Non-metallic Mineral Products". Five test points were selected for each sample, including the center point and four corners 50 mm from the edge, and the average value was taken.

[0062] 2. Yellowness Tendency Test The color parameters of the sample glaze were tested according to GB / T 3979-2008 "Methods for Measuring the Color of Objects" using a colorimeter under D65 standard illuminant and a 10° viewing angle. The b-value is used to evaluate the yellowing tendency of the glaze; the higher the b-value, the more obvious the yellowing tendency of the sample. Five points are tested on each sample, and the average value of the five samples is taken.

[0063] 3. Gloss test The specular gloss of the sample glaze was tested according to GB / T 13891-2008 "Determination of Specular Gloss of Building Facing Materials" using a 60° incident angle. Five points were tested on each sample, and the average value of the five samples was taken.

[0064] 4. Surface roughness test The surface roughness Ra of the glaze was tested using a surface roughness meter. Five different areas were selected for testing on each sample, with a single measurement length of 4 mm. The average value of the five samples was taken. The lower the Ra value, the smoother the glaze surface.

[0065] 5. Testing the number of pinholes and karst caves The surface quality inspection method was carried out in accordance with GB / T 3810.2-2016 "Test Methods for Ceramic Tiles - Part 2: Inspection of Dimensions and Surface Quality" and combined with the glaze defect evaluation requirements of this invention. The samples were placed under a light source with an illuminance of not less than 600 lx and observed vertically at a distance of 1 m from the sample surface. A 10x magnifying glass was used to confirm pinholes and cavities in the glaze surface. The number of pinholes and cavities with a diameter of not less than 0.2 mm on the surface of each sample was recorded and converted into the number of defects per square meter.

[0066] Table 1 Indicator Test Results

[0067] The results above show that Examples 1-5 all exhibited high whiteness, low yellowing tendency, high gloss, low surface roughness, and fewer pinholes and cavities. Among them, Example 1 showed the best overall effect, indicating that the present invention, through the synergistic effect of modified lithium tailings composite powder, calcium titanate compound crystallization component, phytic acid interface anchoring component, ammonium pentaborate melting component, and zinc-aluminum-boron-silicon frit, can effectively improve the opacity whitening, glaze smoothness, and defect control of the surface coating of lithium tailings-based ceramic bricks.

[0068] Examples 2 and 3 show that when the amount of modified lithium tailings composite powder varies within a certain range, the coating material can still maintain good whiteness and glaze smoothness. However, when the amount of modified lithium tailings composite powder is too high, the glaze melting and spreading performance decreases slightly, gloss decreases, and roughness and the number of defects increase slightly. Examples 4 and 5 show that there is an optimal dosage range for the calcium titanate compound crystallizing component. When the dosage is too low, the formation of opacified crystallization centers is insufficient, and when the dosage is too high, it may lead to local over-crystallization or microscopic unevenness of the glaze surface. Therefore, the ratio in Example 1 is more conducive to balancing whiteness, low yellowing, and glaze smoothness.

[0069] Comparative Example 1, using unmodified lithium tailings powder, showed a significant decrease in whiteness and a marked increase in pinholes and cavities, indicating that it is difficult to achieve good glaze quality when lithium tailings are directly used in surface glazes. Comparative Example 2, without the addition of the calcium titanate-based crystallization component, showed a significant decrease in both whiteness and gloss, indicating that this crystallization component is key to the formation of opacity crystallization centers. Comparative Example 3, with only the addition of dihydroxybis(ammonium lactate)titanium(IV) aqueous solution, showed some improvement in whiteness, but... The significantly increased value indicates that titanium source alone easily causes yellowing; in Comparative Example 4, only calcium lactate pentahydrate was added, resulting in limited improvement in whiteness, indicating that calcium source alone is difficult to form effective opacification crystallization centers. This proves that there is a synergistic effect between dihydroxybis(ammonium lactate)titanium(IV) aqueous solution and calcium lactate pentahydrate.

[0070] Comparative Example 5, which used TiO2 powder and calcium carbonate powder to replace the calcium-titanium lactate composite crystallization component, still showed lower results than Example 1. This indicates that the present invention is not simply about adding titanium-calcium inorganic powder, but rather about forming a more uniform interfacial crystallization-inducing layer on the surface of lithium tailings particles through a water-soluble precursor. Comparative Example 6 did not add phytic acid aqueous solution, indicating that phytic acid plays an important role in the interfacial anchoring and uniform distribution of zirconium, titanium, and calcium components. Comparative Example 7 did not add ammonium pentaborate, resulting in a decrease in glaze gloss and an increase in defects, indicating that ammonium pentaborate can regulate glaze melting and venting windows. Comparative Example 8 did not add zinc-aluminum-borosilicate frit, resulting in a significant decrease in glaze smoothness and gloss, indicating that zinc-aluminum-borosilicate frit can improve the later-stage melting and spreading performance of the glaze.

Claims

1. A ceramic tile surface coating material, characterized in that, The product is prepared by weight from the following raw materials: 30-70 parts modified lithium tailings composite powder, 2-8 parts zinc-aluminum-boron-silicon frit, 3-12 parts sodium feldspar, 2-10 parts nepheline syenite, 8-18 parts calcined kaolin, 2-10 parts calcined alumina, 2-8 parts wollastonite, 1-5 parts calcined talc, 1-5 parts dolomite, and 30-50 parts water. The modified lithium tailings composite powder is prepared by a method including the following steps: lithium tailings are subjected to magnetic separation to remove iron to obtain low-iron lithium tailings powder, which is then mixed with a crystallization inducer for interface modification treatment, and then heat-treated at 500-650℃. Based on 100 parts by weight of the low-iron lithium tailings powder, the crystallization inducing agent comprises: 2-5 parts of 50wt% phytic acid aqueous solution, 5-10 parts of zirconium carbonate ammonium solution with a mass fraction of 18-25% (calculated as ZrO2), 15-22 parts of crystallization component, 0.5-1.5 parts of ammonium pentaborate, and 0.1-0.5 parts of ammonium polyacrylate; the crystallization component is composed of dihydroxybis(ammonium lactate)titanium(IV) and calcium lactate pentahydrate in a mass ratio of 1:(1.8-2.2).

2. The ceramic tile surface coating material according to claim 1, characterized in that, The heat treatment temperature is 520-600℃, and the holding time is 30-90min.

3. The ceramic tile surface coating material according to claim 1, characterized in that, The zinc-aluminum-boron-silicon frit comprises, by mass percentage: SiO2 45-55%, B2O3 12-18%, Al2O3 8-14%, ZnO 8-15%, Na2O+K2O 4-8%, CaO 2-6%, and has a softening temperature of 680-760℃.

4. The ceramic tile surface coating material according to claim 1, characterized in that, The conditions for the interface modification treatment are: pH value of 7.5-9.0, temperature of 50-70℃, and time of 30-90min.

5. The ceramic tile surface coating material according to claim 1, characterized in that, It also contains: 0.1-0.8 parts of sodium carboxymethyl cellulose and 0.1-0.6 parts of sodium tripolyphosphate.

6. The ceramic tile surface coating material according to claim 1, characterized in that, The Fe2O3 content in the low-iron lithium tailings powder is no higher than 0.75%, the residue on a 325-mesh sieve is less than 0.5%, and the D90 is less than 22μm.

7. A method for preparing a ceramic tile surface coating material according to any one of claims 1-6, characterized in that, include: After mixing all the raw materials, wet ball milling and sieving are performed to adjust the specific gravity to 1.75-1.85 g / cm³. 3 The flow rate is increased to 40-50 seconds, and the mixture is aged to obtain the final product.

8. The method of applying the ceramic tile surface coating material according to any one of claims 1-6 in the surface decoration of ceramic tiles, characterized in that, include: The surface coating material of the ceramic tile is applied to the surface of the ceramic tile body by bell glazing, with a dry glaze application amount of 200-250g / m². After glazing, it is dried at 90-110℃ for 10-25min, and then sent to a roller kiln for firing at 1100-1250℃ for 5-12min. After cooling, the ceramic tile with the surface coating is obtained.

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