Ceramic glaze using raffinate acid and preparation method thereof

Abstract

This invention discloses a ceramic glaze that utilizes residual raffinate as a resource. It is a powder prepared primarily from residual raffinate. The raw materials used and their weight percentages include: 16-20 parts residual raffinate, 5-8 parts citric acid, 4-7 parts alcohol additives, and 5-10 parts water. This invention uses industrial by-product residual raffinate as the main raw material, fully recovering and utilizing the effective elements in the residual raffinate. Furthermore, by combining a control mechanism based on citric acid and alcohol additives, as well as segmented temperature control processes, it can achieve high-value-added resource utilization of residual raffinate in the glaze field, resulting in significant economic and environmental benefits. The obtained ceramic glaze achieves good sintering and crystallization effects, gloss, and mechanical properties, and has wide applicability.

Description

Technical Field

[0001] This invention belongs to the field of ceramic glaze technology, specifically relating to a ceramic glaze that utilizes residual leaching acid and its preparation method. Background Technology

[0002] Ceramic glaze is a thin, glassy layer applied to the surface of a ceramic body, playing a vital role in decoration, protecting the body, and improving product performance. Traditional ceramic glazes typically use high-purity chemical raw materials and natural minerals, resulting in high raw material costs and requiring significant energy consumption during production.

[0003] Residual acid from raffinate is a residue from the wet-process phosphoric acid purification process, containing a certain concentration of acid radicals and a large number of metal ions. Currently, the main methods for treating residual acid from raffinate include precipitation and extraction, which can be used to produce fertilizers for large-scale utilization. Although these methods can consume a large amount of raw acid, they also have problems such as easy scaling during production, affecting the stable operation of the system, and low added value of the product.

[0004] While existing technologies have attempted to utilize industrial waste acid to prepare ceramic glazes, most suffer from drawbacks such as unstable performance, poor glaze quality, and low waste utilization. Some studies have directly added industrial waste acid to the glaze formulation, resulting in violent and uncontrollable gas release during firing, easily leading to defects such as bubbles, pinholes, and dark cracks. Furthermore, waste acid exhibits poor compatibility with other raw materials, resulting in uneven glaze melting, insufficient thermal stability, and difficulty in forming a dense and uniform glaze surface. Therefore, further development of ceramic glazes that can efficiently utilize industrial waste acid while ensuring excellent performance, along with their preparation methods, has significant economic and environmental value. Summary of the Invention

[0005] The main objective of this invention is to overcome the problems and shortcomings of the existing technology and provide a ceramic glaze prepared using residual acid from phosphogypsum by-products. This glaze can efficiently utilize industrial by-products of residual acid, reduce raw material costs, and simultaneously achieve good sintering and crystallization effects, gloss, and mechanical properties.

[0006] Another objective of this invention is to provide a method for preparing the above-mentioned ceramic glaze, which is simple in process, convenient in operation and highly controllable, and suitable for large-scale production.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A ceramic glaze that utilizes residual raffinate as a resource is a powder prepared using industrial residual raffinate as the main raw material. The raw materials and their weight percentages include: 16-20 parts residual raffinate, 5-8 parts citric acid, 4-7 parts alcohol additives, and 5-10 parts water.

[0008] In the above scheme, the total concentration of raffinate (total concentration of solid components) is 1-6 wt%; the main chemical components and their contents include: P 290-342 g / L, Mg 28-31 g / L, Fe 1.4-4.1 g / L, Al 15-22 g / L, Pb 1.40-4.06 g / L, Hg 1.24-4.14 g / L, Ca 1.19-13.24 g / L, Si 0.10-0.54 g / L, and F 0.15-0.17 g / L. Based on the characteristics of raffinate with a concentration of 1-6 wt%, the present invention is suitable for 16-20 parts by weight of raffinate, which is beneficial to ensuring pH control and gel structure stability of the system and can meet the resource utilization needs of raffinate with different concentrations.

[0009] Furthermore, the pH value of the residual acid is -0.8 to -0.1.

[0010] In the above scheme, the residual acid is stirred evenly before use and then the supernatant is obtained by centrifugation.

[0011] In the above scheme, the alcohol additive can be selected from alcohol components such as ethylene glycol, propylene glycol, glycerol, and polyethylene glycol, which have similar flocculation and dispersion effects.

[0012] This invention also provides a method for preparing the above-mentioned ceramic glaze using recycled raffinate, comprising the following steps: 1) Raw material mixing: Weigh each raw material according to the ratio, mix and stir the weighed raw materials to obtain a mixture; then stir the obtained mixture at low temperature; 2) Intermediate heat treatment; The mixture after low-temperature stirring is heated for low-temperature heat treatment; 3) Grinding and calcination: The product obtained from low-temperature heat treatment is ground into powder and then calcined at a medium temperature in air; 4) Acid washing and purification: The calcined powder is acid washed, dried, and then the ceramic glaze containing the residual acid from the extraction process is obtained.

[0013] In the above scheme, the mixing step 1) includes: first, mixing citric acid and water evenly, then adding residual raffinate and stirring evenly, and finally adding alcohol additives.

[0014] Furthermore, the residual acid and alcohol additives are added dropwise at a rate of 1-2 drops / s.

[0015] In the above scheme, the heating rate of calcination is 5-10℃ / min.

[0016] In the above scheme, the low temperature in step 1) is 80-100℃ (oil bath or other methods), and the time is 24-48h.

[0017] This invention first involves dissolving citric acid in water to form a pH buffer system, then slowly adding residual raffinate, and finally adding an ethylene glycol additive. The resulting mixture is then subjected to low-temperature stirring at 80-100°C. Through the synergistic effect of citric acid and the alcohol additive, the residual raffinate undergoes in-situ chelation modification. The citric acid, through its polycarboxyl structure, interacts with the Fe in the residual raffinate. 3+ Al 3+ Mg 2+ Metal ions form stable chelates, inhibiting ion aggregation, and simultaneously construct a pH buffer system to counteract strong acid shocks. Alcohol-based additives construct a three-dimensional network structure through hydrogen bonding, enhancing gel stability and exerting steric hindrance effects to further disperse components and improve compatibility. Based on the above raw material system and mechanism of action, a uniform and stable gel structure is constructed, enabling precise pH control and improving the compatibility of components within the residual acid system. This effectively solves application problems such as pH runaway, component aggregation, violent gas release during calcination, and the formation of bubbles and pinholes caused by directly adding industrial waste acid.

[0018] In the above scheme, the low-temperature heat treatment in step 2) uses a temperature of 200-250 ℃ and a time of 3-5 h.

[0019] In the above scheme, in step 3), the medium-temperature calcination temperature is 550-600℃ and the time is 10-15 h.

[0020] In the above scheme, in step 4), the pickling time is 4-6 hours; dilute acid with a pH of 2.0-4.0 is used for pickling.

[0021] Furthermore, the dilute acid is dilute nitric acid.

[0022] In the above scheme, in step 4), the drying temperature is 60-80℃ and the drying time is 4-6 hours.

[0023] In the above scheme, the particle size distribution of the obtained ceramic glaze is relatively concentrated, with D50 controlled in the range of 75-85 μm and D90 controlled in the range of 185-195 μm; obvious phosphate decomposition peaks appear at 700~750℃.

[0024] Furthermore, the obtained ceramic glaze is fired at high temperature to form a glaze surface.

[0025] In the above scheme, the high-temperature calcination step includes: heating to 1100-1200℃ at a rate of 5-10℃ / min, and holding the temperature for calcination for 15-30 min.

[0026] Furthermore, the resulting glaze exhibits an "ice crackle" effect, a bright luster, and is free of pinholes, bubbles, and glaze shrinkage defects.

[0027] The principles of this invention include: This invention uses industrial residual acid as the main raw material to prepare ceramic glaze. To effectively improve the problems of violent gas release during the firing process, which easily leads to glaze defects such as bubbles, pinholes, and dark cracks, and to improve the problems of metal ion agglomeration in waste acid affecting the melting uniformity and thermal stability of the glaze, the following special improvement methods are mainly adopted to achieve application breakthroughs: 1) Compound Functional Auxiliary Agent System: Addressing the application bottlenecks of residual acid systems, such as strong acidity, complex metal ion composition, easy agglomeration, and poor thermal stability, this invention proposes and constructs for the first time a compound functional system with citric acid as the core and alcohol-based auxiliary agents as synergies. This system promotes the triple effects of pH buffering, metal ion chelation, and gel construction, effectively solving industry problems such as metal ion agglomeration in waste acid, uneven glaze melting, and firing defects. Its core improvement and control methods include the following: 1-1: Control of Feeding Sequence and Pre-construction of pH Buffer System: This invention first constructs a stable pH buffer system (citric acid buffer solution) using citric acid and water. Then, residual raffinate is slowly added at a rate of 1-2 drops / s, ensuring that the pH of the solution remains stable within the range of 3.0-4.5 during the addition process. Finally, an alcohol-based auxiliary agent is added at a rate of 1-2 drops / s. Conventional processes typically add chelating agents directly to waste acid, which can lead to sudden changes in local pH and instantaneous aggregation of metal ions. Furthermore, the strong acidity of residual raffinate can instantly disrupt conventional buffer systems. This invention, using a raw material system based on residual raffinate, citric acid, and an alcohol-based auxiliary agent, along with the aforementioned feeding mechanism, avoids pH fluctuations from the source, promotes stable buffering under strong acidity, and provides a stable environment for subsequent gel network construction.

[0028] 1-2: Low-temperature gelation: The obtained mixture is first stirred continuously in an oil bath at 80-100℃ for 24-48h. Combined with the chelating effect of citric acid and the flocculation and dispersion effect of alcohol additives, a uniform and stable three-dimensional gel network is constructed, and the pH value of the system is maintained in a stable range of 3.0-4.5. Among them, the introduced citric acid affects the Fe in the residual acid. 3+ Mg 2+ The formation of chelates with adjustable coordination ratios by metal ions eliminates the need for strong chelating agents such as EDTA, ensuring uniform dispersion of metal ions within the gel network without localized aggregation. Furthermore, the hydroxyl and carboxyl groups in citric acid molecules interact through intermolecular hydrogen bonds and undergo hydrogen bond cross-linking with the hydroxyl groups of alcohol-based auxiliaries, promoting the construction of a continuous three-dimensional gel framework. This allows the metal chelates to be uniformly encapsulated within the constructed gel framework network, achieving in-situ modification of the residual acid system and effectively solving problems such as stratification and precipitation in waste acid systems.

[0029] By synergistically controlling the citric acid buffer system and the feeding rate, the pH of the system is stably adjusted to 3.0~4.5. While ensuring the stable chelation of metal ions, problems such as metal hydroxide precipitation and gel network destruction can be effectively avoided. At the same time, it is also beneficial to control the gas release rhythm during firing, effectively avoiding the formation of glaze defects such as bubbles, pinholes, and dark cracks.

[0030] 1-3: Synergistic optimization of raw material ratio: Strictly control the raw material ratio to match the chelation sites of citric acid with the metal ions in the residual acid. At the same time, alcohol additives provide steric hindrance effect to avoid the collapse of gel structure, effectively solve the pH loss problem caused by direct acid addition, and help to control the gas release rhythm during firing, avoid defects such as bubbles and pinholes, and ensure that the glaze is uniform and dense. 2) Segmented temperature control process: Through a three-stage segmented temperature control process of low-temperature oil bath gelation, medium-temperature pre-calcination, and high-temperature final firing, residual small molecules and free acids in the system can be effectively removed, the crystallization behavior of the glaze can be optimized, and based on a step-by-step temperature control mechanism with a rate of 5-10℃ / min, the gas release rhythm during firing can be effectively controlled, so that the gas is discharged slowly and evenly, effectively suppressing defects such as bubbles and pinholes; at the same time, the crystallization behavior of the glaze can be optimized, and the density and mechanical properties of the glaze surface can be improved.

[0031] Compared with the prior art, the beneficial effects of the present invention include: 1) This invention can fully recover and utilize the effective elements in the residual acid, realizing the high-value-added resource utilization of residual acid in the ceramic glaze system; 2) The ceramic glaze obtained by this invention exhibits a higher weight loss peak at 700-750℃, and the weight loss is controllable and moderate, which can form a uniform and regular ice crack glaze surface; at the same time, it can significantly reduce defects such as bubbles and pinholes; the glaze powder has a uniform particle size distribution, good meltability and stability, excellent acid resistance, alkali resistance that meets the characteristics of ice crack glaze, and chemical stability that meets the requirements for daily use and decorative ceramics. 3) The preparation process involved in this invention is simple, low-cost, and has a high yield, and has both environmental benefits and economic value. Attached Figure Description

[0032] Figure 1 The XRD patterns are of the ceramic glazes described in Examples 1-2 and Comparative Example 1; Figure 2 Thermogravimetric analysis diagram of the ceramic glaze obtained in Example 1; Figure 3 Thermogravimetric analysis diagram of the ceramic glaze obtained in Example 2; Figure 4 Thermogravimetric analysis diagram of the ceramic glaze described in Comparative Example 1; Figure 5 The images show the morphology of the glaze powder obtained in Examples 1 and 2. Figure 6 These are morphological images of the glaze surfaces obtained in Examples 1-3. Detailed Implementation

[0033] The applicant will now provide a more detailed description of the present invention with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention. However, the following content should not be construed as limiting the scope of protection claimed in the claims of the present invention.

[0034] The present invention will be further described in detail below with reference to specific embodiments. Unless otherwise specified, all raw materials used in the present invention are commercially available.

[0035] In the following examples, the solid component concentrations of the raffinate used were 1 wt% and 6 wt%, respectively, provided by a phosphate chemical company in Hubei Province. The main component content information obtained by characterizing the two concentrations of raffinate using inductively coupled plasma atomic emission spectrometry (ICP) and X-ray fluorescence spectrometry (XRF) is as follows: The main chemical components and contents of 1 wt% residual acid are as follows: P 341.52 g / L, Mg 28.268 g / L, Fe 1.447 g / L, Al 15.585 g / L, Pb 1.406 g / L, Hg 1.247 g / L, Ca 1.194 g / L, Si 0.1 g / L, F 0.161 g / L; pH value is -0.8. The main chemical components and contents of the 3wt% residual acid raffinate include P 323.26 g / L, Mg 29.256 g / L, Fe 3.665 g / L, Al 18.286 g / L, Pb 3.461 g / L, Hg 3.82 g / L, Ca 9.242 g / L, Si 0.325 g / L, and F 0.158 g / L; the pH value is -0.5. The main chemical components and contents of the 6 wt% residual acid are as follows: P 290.14 g / L, Mg 30.752 g / L, Fe 4.052 g / L, Al 21.635 g / L, Pb 4.051 g / L, Hg 4.139 g / L, Ca 13.234 g / L, Si 0.533 g / L, F 0.155 g / L; pH value is -0.1.

[0036] Furthermore, the residual acid is stirred with an electric stirrer (150 rpm) for 3 hours before use, and then centrifuged at 4000 rpm for 15 minutes before using the supernatant.

[0037] Example 1 A ceramic glaze prepared using residual raffinate, comprising the following raw materials and their respective weight proportions: 16 parts 1wt% residual raffinate, 5 parts citric acid monohydrate, 4 parts ethylene glycol, and 5 parts water; the specific preparation steps of the ceramic glaze are as follows: 1) Raw material mixing: Weigh each raw material according to the above weight proportions, stir and mix evenly to obtain a mixture; the specific addition and stirring steps include: first, mix citric acid and water evenly, then add residual raffinate at a rate of 1-2 drops / s, stir evenly, and finally add ethylene glycol at a rate of 1-2 drops / s, stir evenly to obtain a mixture. The resulting mixture was transferred into a three-necked flask and stirred for 24 h in an oil bath at 80°C. 2) Intermediate heat treatment; the mixture obtained in step 2) is treated at 200 °C for 5 h; 3) Grinding and calcination: Grind the product obtained in step 3) into powder and then calcine it in air at 550 °C for 10 h.

[0038] 4) Acid washing and purification: Add the calcined powder to dilute nitric acid with pH=2.0 and acid wash for 5 h; 5) High-temperature molding: After drying the acid-washed powder for 5 hours, the temperature is increased to 1100 ℃ at a rate of 5℃ / min, held at the temperature for 15 minutes, and then cooled to obtain ceramic glaze.

[0039] Example 2 A ceramic glaze prepared using residual raffinate, comprising the following raw materials and their respective weight proportions: 18 parts 3wt% residual raffinate, 7 parts citric acid monohydrate, 6 parts ethylene glycol, and 8 parts water; the specific preparation steps of the ceramic glaze are as follows: 1) Raw material mixing: Weigh each raw material according to the above weight proportions, stir and mix evenly to obtain a mixture (the feeding and mixing steps are the same as in Example 1); transfer the obtained mixture into a three-necked flask and stir for 36 h under a constant temperature of 90°C in an oil bath. 2) Intermediate preheating treatment; the mixture obtained in step 2) is treated at 220 °C for 4 h; 3) Grinding and calcination: Grind the product obtained in step 3) into powder and then calcine it at 580 °C for 13 h in air.

[0040] 4) Acid washing and purification: Add the calcined powder to dilute nitric acid with pH=2.0 and acid wash for 5 h; 5) High-temperature molding: After drying the acid-washed powder for 5 hours, the temperature is increased to 1150 ℃ at a rate of 8℃ / min, held at the temperature for 20 minutes, and then cooled to obtain ceramic glaze.

[0041] Example 3 A ceramic glaze prepared using residual raffinate, comprising the following raw materials and their respective weight proportions: 20 parts 6wt% residual raffinate, 8 parts citric acid monohydrate, 7 parts ethylene glycol, and 10 parts water; the specific preparation steps of the ceramic glaze are as follows: 1) Raw material mixing: Weigh each raw material according to the above weight proportions, stir and mix evenly to obtain a mixture (the feeding and mixing steps are the same as in Example 1); transfer the obtained mixture into a three-necked flask and stir for 48 h under constant temperature conditions of 100°C oil bath; 2) Intermediate preheating treatment; the mixture obtained in step 2) is treated at 250 °C for 3 h; 3) Grinding and calcination: Grind the product obtained in step 3) into powder and then calcine it at 600 °C for 15 h in air.

[0042] 4) Acid washing and purification: Add the calcined powder to dilute nitric acid with pH=2.0 and acid wash for 5 h; 5) High-temperature molding: After drying the acid-washed powder for 5 hours, the temperature is increased to 1200 ℃ at a rate of 10℃ / min, held at the temperature for 30 minutes, and then cooled to obtain ceramic glaze.

[0043] Comparative Example 1 A commercially available conventional ceramic glaze is mainly composed of traditional mineral raw materials such as quartz, feldspar, and kaolin in conventional proportions. The specific formula is as follows: 30-40 wt% quartz powder, 25-35 wt% potassium feldspar, 15-20 wt% kaolin, 5-10 wt% calcium carbonate, and 5-8 wt% talc. The glaze's properties and sintering characteristics include: a white powdery form, a pH value of 6.5-7.5, good fluidity, and after firing at 1200℃, a glaze surface gloss ≥80, with no obvious bubbles or pinhole defects, serving as a benchmark for conventional, qualified daily-use ceramic glazes.

[0044] Comparative Example 2 An industrial raffinate-based ceramic glaze comprises the following components and their respective weight percentages: 16 parts raffinate (same as in Example 1) and 5 parts water; the specific preparation method includes the following steps: 1) Raw material mixing: Weigh each raw material according to the ratio, stir and mix them directly to obtain a mixture (the feeding and mixing steps are the same as in Example 1); no low-temperature oil bath gelation modification treatment is performed, only stirring at room temperature for 1 hour; 2) Intermediate heat treatment: The mixture is heated at 200℃ for 4 hours; 3) Grinding and calcining: Grind the product into powder and calcine it at 550℃ in air for 10 hours; 4) Acid washing and purification: The calcined powder was acid washed with dilute nitric acid with a pH of 2.0 for 5 hours; 5) High-temperature molding: The acid-washed powder is washed, dried at 60℃ for 5 hours, and then heated to 1100℃ at a rate of 5℃ / min. It is then held at this temperature for 30 minutes to obtain ceramic glaze.

[0045] Comparative Example 3 An industrial raffinate-based ceramic glaze, comprising the following raw materials and their respective weight proportions: 16 parts raffinate (same as in Example 3), 5 parts citric acid, and 5 parts water; the specific preparation method includes the following steps: 1) Raw material mixing and modification: Weigh each raw material according to the ratio, first mix and dissolve citric acid with water, slowly add raffinate and stir evenly, stir only at room temperature for 1 hour, do not perform low temperature oil bath treatment, do not introduce ethylene glycol for flocculation and dispersion, and obtain a mixed liquid; 2) Intermediate heat treatment: The mixture is heated at 200℃ for 4 hours; 3) Grinding and calcining: Grind the product into powder and calcine it at 550℃ in air for 10 hours; 4) Acid washing and purification: The calcined powder was acid washed with dilute nitric acid with a pH of 2.0 for 5 hours; 5) High-temperature molding: The acid-washed powder is washed, dried at 60℃ for 5 hours, and then heated to 1200℃ at a rate of 5℃ / min. It is then held at this temperature for 20 minutes to obtain ceramic glaze.

[0046] Comparative Example 4 An industrial raffinate-based ceramic glaze is prepared using a method largely the same as in Example 1, except that sodium citrate (sodium citrate dihydrate) is used in the same molar amount instead of the citric acid (citric acid monohydrate) described in this invention. Comparative Example 5 An industrial raffinate-based ceramic glaze uses the same formulation system as in Example 1, but the specific preparation method includes the following steps: 1) Raw material mixing stage: The residual raffinate, citric acid, ethylene glycol and water are directly stirred at room temperature for 24 hours, without the oil bath gelation treatment of 80-100℃ of this invention. 2) Calcination stage: Instead of performing the medium-temperature pre-calcination treatment of 550-600℃ as in this invention, the mixture obtained in step 1) is directly heated to 1100℃ at a rate of 5℃ / min and kept at that temperature for calcination for 30min. The remaining operations are exactly the same as in Example 1.

[0047] The ceramic glazes described in Examples 1-2 and Comparative Example 1 were subjected to performance tests, and the test results are as follows.

[0048] 1) XRD test: The phase characterization of the glaze powder samples obtained in Example 1, Example 2 and Comparative Example 1 was performed using an X-ray diffractometer. Test conditions: scanning range 10°~90°, step width 0.02°, scanning speed 2° / min. The results are shown in the figure. Figure 1 As can be seen from the XRD patterns, the main diffraction peaks of the glazes in Examples 1 and 2 include characteristic diffraction peaks with magnesium phosphate crystals as the core, and also match characteristic diffraction peaks of composite phosphates such as aluminum phosphate and iron phosphate; indicating that the glaze material formed after calcination at 1100-1200℃ by the glaze obtained in this invention is a composite crystal phase system with magnesium phosphate as the main body and metal phosphates such as aluminum / iron as auxiliary components.

[0049] 2) Thermogravimetric analysis: The ceramic glazes described in Examples 1 and 2 and Comparative Example 1 were subjected to thermogravimetric analysis in air atmosphere using a thermogravimetric analyzer. The heating rate was 10℃ / min, and the test range was room temperature to 1320℃. The results are shown in the figures below. Figures 2-4 TG-DTG results showed that the glazes obtained in Examples 1 and 2 of this invention exhibited obvious phosphate decomposition peaks at 700-750℃, and the peak temperatures were higher than those in Comparative Example 1. This provides a moderate, uniform, and stable driving force for volume shrinkage during high-temperature firing, resulting in continuous, regular, and clear ice crackle patterns. It overcomes the problems of sparse, unevenly sized, and uncontrollable crackle patterns caused by insufficient shrinkage in commercially available glazes.

[0050] The increased decomposition peak temperature delays gas release to the temperature range where the glaze has begun to melt and the viscosity is moderate. This results in a more stable and gentler gas release, which can significantly reduce defects such as pinholes, bubbles, and dark cracks in the resulting glaze surface, thereby greatly improving the yield and decorative quality of the glaze.

[0051] 3) Particle size distribution: The particle size distribution of the powder was determined by laser particle size analyzer according to the national standard GB / T19077-2024 Particle size analysis by laser diffraction. The D50, D90, D95 and volume average particle size MV of the sample were measured by volume particle size analyzer. The specific test results are shown in Table 1.

[0052] Table 1. Detection results of particle size distribution of ceramic glazes obtained in Examples 1, 2 and Comparative Example 1.

[0053] Data analysis: The three samples exhibit concentrated particle size distribution, good stability, and minimal fluctuation. The D50 is controlled within the range of 75-85 μm, and the D90 is within the range of 185-195 μm, demonstrating high overall particle size matching. The powder particles obtained in Examples 1 and 2 of this invention are of moderate size, without excessively large agglomerates or excessively fine dust. The uniform particle size distribution and good dispersibility ensure stable composition and uniform melting, facilitating the formation of dense, smooth, and consistent finished products, meeting the requirements for large-scale production and application.

[0054] 4) Acid and alkali resistance test: The acid and alkali resistance of the ceramic glazes obtained in each embodiment and comparative example were tested in accordance with the requirements of the national standard GB / T 3810.13-2016. The results are shown in Table 2 and Table 3.

[0055] Table 2. Acid resistance test results of ceramic glazes obtained in Examples 1-3 and Comparative Examples 1-5

[0056] Table 3. Alkali resistance test results of ceramic glazes obtained in Examples 1-3 and Comparative Examples 1-5

[0057] The above results indicate that: The glazes obtained in Examples 1-3, after being immersed in citric acid solution for 8 hours, showed no change in glaze integrity, color, or smoothness, and no significant loss in quality, demonstrating excellent acid resistance. In the strongly alkaline NaOH solution, only slight cracking occurred, consistent with typical characteristics of ice-crack glazes, and the overall chemical stability met the standards for daily-use and decorative ceramics. Comparative Example 2, without any functional additives or modification treatment, resulted in a glaze with extremely poor acid and alkali resistance. After immersion, it exhibited significant corrosion, roughness, large-area cracking, and peeling, failing to meet usage requirements. Comparative Example 3 lacked ethylene glycol flocculant components, resulting in insufficient system dispersibility and structural stability. Its acid and alkali resistance was significantly inferior to the examples, and the glaze was prone to corrosion and cracking. Comparative Example 4 used sodium citrate instead of citric acid, failing to construct the stable gel system and pH buffer environment described in this invention, significantly reducing acid and alkali resistance and resulting in insufficient corrosion resistance of the glaze. Comparative Example 5 did not employ segmented temperature control and low-temperature gelation processes, resulting in poor glaze density and stability, and significantly lower acid and alkali resistance than the examples of this invention.

[0058] In summary, this invention, by combining citric acid-alcohol additives with segmented temperature control, can significantly improve the chemical stability of raffinate-based ceramic glazes and effectively overcome the defects of poor corrosion resistance and easy corrosion and cracking caused by directly using raffinate.

[0059] 5) Gloss test: The gloss of each embodiment and comparative example was tested in accordance with the requirements of the national standard GB / T 3295-2025. The results are shown in Table 4.

[0060] Table 4. Gloss test results of ceramic glazes obtained in Examples 1-3 and Comparative Examples 1-5

[0061] As can be seen from Table 4: The 60° gloss of the glazes obtained in Examples 1-3 were 93.80 GU, 89.39 GU, and 91.55 GU, respectively, all significantly higher than the conventional commercially available glaze (83.20 GU) described in Comparative Example 1. The glazes were bright, smooth, and had excellent decorative effects. Comparative Example 2, without modification or gelation treatment, had numerous defects such as bubbles, pinholes, and glaze shrinkage, resulting in a gloss of only 41.50 GU and extremely poor appearance. Comparative Example 3 lacked ethylene glycol dispersion components, resulting in uneven melting and a rough surface, with a gloss of only 66.70 GU, significantly lower than the examples. Comparative Example 4 used sodium citrate instead of citric acid, leading to pH imbalance and poor crystal development, resulting in a gloss of only 72.30 GU. Comparative Example 5 did not employ a segmented temperature control process, resulting in low glaze density, numerous defects, and a gloss of only 69.80 GU.

[0062] The above results show that the present invention, by combining in-situ gel modification and segmented temperature control, can effectively reduce glaze defects and improve the uniformity and gloss of glaze melting.

[0063] 6) Hardness test: Hardness tests were conducted on each example and comparative example in accordance with the requirements of the national standard GB / T 16534-2023.

[0064] Table 5. Hardness test results of ceramic glazes obtained in Examples 1-3 and Comparative Examples 1-5

[0065] As can be seen from Table 5: The glazes obtained in Examples 1-3 all achieved a Mohs hardness of 7, higher than the 6 of the commercially available glaze in Comparative Example 1. These glazes exhibited superior wear and scratch resistance, better mechanical properties, and greater durability. Comparative Example 2, lacking functional additive formulation and structural control, had a porous glaze with extremely low mechanical strength, resulting in a Mohs hardness of only 4. Comparative Example 3, without the addition of ethylene glycol, had an incomplete gel structure and insufficient density, resulting in a Mohs hardness of 5. Comparative Example 4, using sodium citrate instead of citric acid, failed to form a stable composite phosphate crystal phase, resulting in a glaze hardness of only 5. Comparative Example 5 lacked the key processes of segmented calcination and low-temperature gelation, leading to incomplete glaze crystallization, poor mechanical properties, and a Mohs hardness of 5.

[0066] The above results show that the composite crystalline phase system constructed in this invention can significantly enhance the mechanical strength and hardness of the glaze surface, making it less prone to scratches and wear during long-term use.

[0067] To visually characterize the morphology and glaze effect of the samples, the appearance of the raw glaze powder and the actual glaze surface after firing were observed. See details below. Figure 5 The left image shows Example 2, and the right image shows Example 1. Figure 5 As can be seen, the glaze powder obtained by this invention is a uniform blackish-gray powder with good dispersibility and no obvious agglomeration or clumping.

[0068] Figure 6 The glaze surface appearance after sintering shows that the glaze surfaces obtained in Examples 1 to 3 (from top to bottom are Examples 1, 2, and 3) exhibit an "ice crack" effect, have a bright luster, and are free of pinholes, bubbles, and glaze shrinkage defects. The appearance quality is excellent and meets the requirements for ceramic glaze application.

[0069] The embodiments of the present invention have been described in detail above, but this should not be construed as limiting the scope of protection of the present invention. All equivalent variations and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A ceramic glaze for resource utilization of extraction residue acid, characterized in that, It is a powder prepared mainly from residual raffinate; The raw materials and their respective weight percentages include: 16-20 parts of residual raffinate, 5-8 parts of citric acid, 4-7 parts of alcohol additives, and 5-10 parts of water.

2. The ceramic glaze according to claim 1, characterized in that, The total concentration of the residual acid is 1-6 wt%; the main chemical components and their contents include: P 290-342 g / L, Mg 28-31 g / L, Fe 1.4-4.1 g / L, Al 15-22 g / L, Pb 1.40-4.06 g / L, Hg 1.24-4.14 g / L, Ca 1.19-13.24 g / L, Si 0.10-0.54 g / L, F 0.15-0.17 g / L.

3. The ceramic glaze according to claim 1, characterized in that, The pH value of the residual acid is -0.8 to -0.

1.

4. The ceramic glaze according to claim 1, characterized in that, The alcohol additive is one or more of ethylene glycol, propylene glycol, glycerol, and polyethylene glycol.

5. The method for preparing ceramic glazes utilizing residual raffinate as described in any one of claims 1 to 4, characterized in that, Includes the following steps: 1) Raw material mixing: Weigh each raw material according to the ratio, mix and stir the weighed raw materials to obtain a mixture; then stir the obtained mixture at low temperature; 2) Intermediate heat treatment; The mixture after low-temperature stirring is heated for low-temperature heat treatment; 3) Grinding and calcination: The product obtained from low-temperature heat treatment is ground into powder and then calcined at a medium temperature in air; 4) Acid washing and purification: The calcined powder is acid washed, dried, and then the ceramic glaze containing the residual acid from the extraction process is obtained.

6. The preparation method according to claim 5, characterized in that, Step 1) The raw material mixing step includes: first, mixing citric acid and water evenly, then adding residual raffinate and stirring evenly, and finally adding alcohol auxiliaries.

7. The preparation method according to claim 5, characterized in that, Step 1) uses a low-temperature stirring temperature of 80-100℃ for 24-48h; Step 2) uses a low-temperature heat treatment at 200-250℃ for 3-5h; Step 3) uses a medium-temperature calcination at 550-600℃ for 10-15h.

8. The preparation method according to claim 5, characterized in that, Pickling time is 4-6 hours; pickling is carried out using dilute acid with a pH of 2.0-4.

0.

9. The preparation method according to claim 5, characterized in that, The ceramic glaze is further fired at high temperature to form a glaze surface.

10. The preparation method according to claim 9, characterized in that, The high-temperature calcination step includes: heating to 1100-1200 ℃ at a rate of 5-10℃ / min, and holding the temperature for calcination for 15-30 min.

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