Selenium-rich ceramic capable of releasing selenium element and preparation method thereof
Selenium-enriched ceramics were prepared by using specific ratios and process steps, which solved the problems of selenium volatilization and heavy metal residue, and achieved stable selenium release and excellent mechanical properties, making them suitable for the industrial production of food contact ceramic products.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-07
- Publication Date
- 2026-06-30
AI Technical Summary
Existing selenium-enriched ceramic technologies suffer from severe selenium volatilization, excessive heavy metal residues, uncontrollable release concentrations, and vague process parameters, making it difficult to achieve safe and stable industrial production.
Using natural bone meal, kaolin, quartz and feldspar as basic raw materials, combined with high-purity natural selenium powder and a specific glaze ratio, selenium-enriched ceramics that meet food safety standards are prepared through steps such as ball milling, filtration, clay refining, shaping, bisque firing, base glaze sintering and selenium-enriched glaze bonding.
It achieves stable and slow release of selenium, with heavy metal migration levels below national standards, excellent thermal stability and mechanical properties, and well-defined process parameters, making it suitable for industrial production.
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of ceramic materials for food contact, specifically a selenium-enriched ceramic that can release selenium slowly and its preparation method. Background Technology
[0002] Selenium is an essential trace element for the human body, participating in various physiological metabolisms and playing important roles such as anti-oxidation and enhancing immunity. Stable incorporating selenium into ceramic products allows for slow-release of selenium during daily use, providing a convenient and safe way to supplement the body with selenium.
[0003] Existing selenium-enriched ceramic technology has many drawbacks: First, direct high-temperature doping of selenium raw materials easily leads to a large amount of selenium volatilization and poor slow-release effect; second, natural selenium-enriched ore has not been deeply purified, and the residue of heavy metal cadmium exceeds the standard, which does not meet the food contact safety requirements; third, the selenium release concentration is uncontrollable, with too high a concentration posing a safety risk and too low a concentration lacking functionality; fourth, the process parameters are vague, making it difficult to achieve stable industrial production, and the national safety standards for food contact ceramics are not strictly implemented.
[0004] Therefore, developing a selenium-rich ceramic preparation technology that features stable selenium release, no heavy metal residue, compliant process, and industrial production capability has become an urgent problem to be solved in this field. Summary of the Invention
[0005] In view of the above situation and to overcome the defects of the prior art, the present invention provides a selenium-enriched ceramic that can release selenium element slowly and a method for preparing the same, which effectively solves the problems mentioned in the background.
[0006] To achieve the above objectives, the present invention provides the following technical solution: a selenium-enriched ceramic that can slowly release selenium, wherein the raw material components and mass ratio are: natural bone meal: kaolin: quartz: feldspar = 1:5:2:2; The selenium-enriched glaze layer consists of selenium-enriched surface glaze and natural selenium powder, with a mass ratio of selenium-enriched surface glaze to natural selenium powder = 10:1. The natural selenium powder is made from natural selenium-rich ore through water washing, magnetic separation, acid washing to remove cadmium, and grinding to 300 mesh.
[0007] Preferably, the finished product has a selenium migration of 0.01-0.06 mg / L, a lead migration of ≤0.5 mg / L, and a cadmium migration of ≤0.05 mg / L, which meets the national food safety standard GB 4806.4-2016.
[0008] Preferably, the material exhibits thermal stability of not cracking upon rapid cooling from 180℃ to 20℃, a water absorption rate of ≤0.5%, and a flexural strength of ≥80MPa. A method for preparing selenium-enriched ceramics with slow-release selenium element includes the following steps: S1. Ingredients: Weigh the raw materials according to the mass ratio of natural bone meal: kaolin: quartz: feldspar = 1:5:2:2. The raw materials are high-purity, pollution-free and meet the safety requirements for food contact materials. S2. Ball milling pulping: The mixed raw materials are ball milled at 300 rpm for 48 hours until the pulp fineness reaches 200 mesh, and the output is a uniform pulp without agglomeration and with good flowability; S3, Filtering, Refining, and Molding: Vacuum filter the mud until the moisture content of the mud cake is 25%±1%. After three vacuum refining processes, the mud is hydraulically molded under a pressure of 50 MPa and held for 30 seconds to obtain a uniform blank. S4. Blank treatment: Air dry naturally for 72 hours at a temperature of 25±3℃ and relative humidity of ≤60%, and lightly sand with 800-grit wet sandpaper to remove burrs; S5. High-temperature bisque firing: Heat to 1320℃ at a rate of 5℃ / minute, hold for 2 hours, and cool naturally to room temperature to obtain a ceramic embryo. S6. Embryo surface treatment: Wipe the bisque-fired body with a soft cloth or remove dust with compressed air, without mechanical polishing; S7. Base glaze sintering: Apply the base glaze by spraying, with a thickness of 0.1 mm, and keep it at 1180℃ for 1.5 hours to obtain a smooth and defect-free base glaze layer; S8. Preparation of natural selenium powder: Natural selenium-rich ore is washed with water, magnetically separated to remove impurities, acid-washed with dilute hydrochloric acid or citric acid solution to remove cadmium, ground to 300 mesh, dried and stored in a dark, sealed container. S9. Selenium-enriched glaze bonding: Selenium-enriched glaze and natural selenium powder are ball-milled together for 2 hours at a mass ratio of 10:1 to prepare a selenium-enriched glaze slurry. The glaze is sprayed with a thickness of 0.15 mm and kept at 1180℃ for 2 hours to allow the glaze layer to melt and encapsulate selenium elements to form a stable slow-release structure. S10. Finished Product Inspection: Inspect appearance, physical properties and food safety indicators, and isolate and handle unqualified products. S11. Post-processing and packaging: Wash with deionized water, sterilize with ultraviolet light or ≥120℃ high-temperature steam for 30 minutes, and then package aseptically for food grade.
[0009] Preferably, the material is ground to 300 mesh in S8 to prevent the selenium from volatilizing.
[0010] Preferably, the finished product testing is conducted in accordance with GB 4806.4-2016 and GB / T 3532-2022, and the selenium migration is controlled within 0.01-0.06 mg / L.
[0011] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention provides safe selenium supplementation, with selenium migration within a safe and effective range, posing no risk of overdose, and lead and cadmium levels far below national standard limits; 2. This invention has excellent performance, with thermal stability, flexural strength, and water absorption meeting the standards, thus satisfying the long-term use requirements of daily-use ceramics; 3. The process of this invention is stable, with clear and traceable parameters, making it suitable for industrial mass production; 4. This invention has a wide range of applications and can be used to make various food contact ceramic products such as tableware, tea sets, and wine sets. Detailed Implementation
[0012] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0013] This invention provides a selenium-enriched ceramic that can release selenium in a controlled manner. Selenium-rich ceramic components Basic ceramic raw materials (by mass): natural bone meal: kaolin: quartz: feldspar = 1:5:2:2; Functional component: Natural selenium powder obtained by purifying and grinding natural selenium-rich minerals; Glaze system: base glaze, selenium-enriched top glaze, with a mass ratio of selenium-enriched top glaze to natural selenium powder of 10:1.
[0014] Raw material requirements: All raw materials must be of high purity and free from pollution. Natural bone meal and natural selenium-rich minerals must be accompanied by third-party testing reports to ensure that heavy metals do not exceed the standards and that they meet the safety standards for food contact materials.
[0015] The preparation steps of selenium-enriched ceramics with slow-release selenium are as follows: S1. Ingredients: Weigh natural bone meal, kaolin, quartz, and feldspar according to the mass ratio. All raw materials meet food contact safety requirements. S2. Ball milling pulping: The ball milling speed is 300 rpm, the ball milling time is 48 hours, the pulp fineness reaches 200 mesh, and the output state is uniform without particle agglomeration and with good fluidity; S3, Filtering, Refining, and Shaping: Vacuum filter the mud until the moisture content of the mud cake is 25%±1%; vacuum refine the mud 3 times to remove air bubbles and increase the density of the green body; hydraulically shape at 50 MPa for 30 seconds to ensure uniform structure of the green body. S4. Body treatment: Ambient temperature 25±3℃, relative humidity ≤60%, air dry for 72 hours; lightly sand with 800-grit wet sandpaper to remove burrs and flash, improve glaze adhesion, and do not perform high-gloss polishing on the unglazed body. S5. High-temperature bisque firing: The heating rate is 5℃ / minute, from room temperature to 1320℃, held for 2 hours, and then naturally cooled to room temperature to obtain a ceramic embryo. S6. Embryo surface treatment: Clean and remove dust with a soft cloth or compressed air. Do not mechanically polish during the unglazed stage to avoid affecting the adhesion of the glaze. S7. Base glaze sintering: Apply base glaze by spraying, with a thickness of 0.1 mm; fire at 1180℃ and hold for 1.5 hours, resulting in a smooth glaze surface without pinholes or glaze runs; S8. Preparation of natural selenium powder: Natural selenium-rich ore is washed with water and magnetically separated to remove impurities; it is then soaked in dilute hydrochloric acid or citric acid solution to remove cadmium; it is ground to 300 mesh; and then dried, protected from light, and stored in an airtight container. S9. Selenium-enriched glaze bonding: Selenium-enriched glaze and natural selenium powder are ball-milled together at a mass ratio of 10:1 for 2 hours to obtain a uniform selenium-enriched glaze slurry; the glaze is sprayed and applied with a glaze layer thickness of 0.15 mm; it is then sintered at 1180℃ for 2 hours, where the glaze layer melts and encapsulates the selenium element, forming a stable crystalline structure and achieving a slow-release function. S10. Finished Product Inspection: Appearance: No cracks, no pinholes, no color difference, and the glaze surface is smooth and flat; Physical properties: No cracking after rapid cooling from 180℃ to 20℃, water absorption ≤0.5%, flexural strength ≥80 MPa; Food safety testing (GB 4806.4-2016): Lead migration ≤0.5mg / L, Cadmium migration ≤0.05mg / L, Selenium migration 0.01-0.06mg / L; Non-compliant products shall be isolated and not allowed to flow into the next process. S11. Post-processing and packaging: Rinse with deionized water; sterilize with ultraviolet light or ≥120℃ high-temperature steam for 30 minutes; food-grade aseptic packaging, labeled with production batch and expiration date.
[0016] This invention implementation standard GB 4806.4-2016 National Food Safety Standard for Ceramic Products; GB / T 3532-2022 "Daily-use Porcelain"; The product's lead and cadmium migration, selenium migration, thermal stability, water absorption, and flexural strength all meet the requirements for superior grade products as specified in the above standards.
[0017] Specifically, the basic raw materials of this invention are natural bone meal: kaolin: quartz: feldspar in a specific ratio of 1:5:2:2, resulting in a green body with high density, uniform structure, and excellent safety and mechanical properties. Natural selenium-rich ore is purified by water washing, magnetic separation, and acid washing to remove cadmium, thoroughly removing harmful heavy metals and retaining selenium to the maximum extent. The selenium-enriched glaze uses a 10:1 ratio, and the glaze layer melts and encapsulates the selenium element, achieving a stable and controllable slow release of 0.01-0.06 mg / L; The entire process is traceable, key parameters are strictly compliant with national safety standards for food contact ceramics, and industrial production is feasible. Example 1:
[0018] Ingredients: 1 kg natural bone meal, 5 kg kaolin, 2 kg quartz, 2 kg feldspar; Ball mill: 300 rpm, 48 hours, 200 mesh; Filtering and refining the mud into shape: moisture content 25%, refining the mud 3 times, holding pressure at 50 MPa for 30 seconds; Air dry: 25℃, 50% humidity, 72 hours, sand with 800-grit sandpaper; Plain roasting: Increase the temperature to 1320℃ at a rate of 5℃ / minute, and keep warm for 2 hours; Base coat: Spray 0.1 mm, keep warm at 1180℃ for 1.5 hours; Selenium powder preparation: Selenium-rich ore is washed, magnetically separated, and acid-washed to a fineness of 300 mesh; Selenium-enriched glaze: glaze: selenium powder = 10:1, ball milling for 2 hours, spraying 0.15 mm, heat preservation at 1180℃ for 2 hours; Test results: All indicators meet the standards; Post-processing: Steam sterilization at 121℃ for 30 minutes, then aseptic packaging.
[0019] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0020] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A selenium-enriched ceramic that can slowly release selenium, characterized in that, The raw material composition and mass ratio are: natural bone meal: kaolin: quartz: feldspar = 1:5:2:2; The selenium-enriched glaze layer consists of selenium-enriched surface glaze and natural selenium powder, with a mass ratio of selenium-enriched surface glaze to natural selenium powder = 10:
1. The natural selenium powder is made from natural selenium-rich ore through water washing, magnetic separation, acid washing to remove cadmium, and grinding to 300 mesh.
2. The selenium-enriched ceramic with slow-release selenium element according to claim 1, characterized in that, The finished product has a selenium migration of 0.01-0.06 mg / L, a lead migration of ≤0.5 mg / L, and a cadmium migration of ≤0.05 mg / L, which meets the national food safety standard GB 4806.4-2016.
3. The selenium-enriched ceramic with slow-release selenium element according to claim 1, characterized in that, It has thermal stability of 180℃ to 20℃ without cracking after rapid cooling, water absorption rate ≤0.5%, and flexural strength ≥80MPa.
4. A method for preparing selenium-enriched ceramics with slow-release selenium element, characterized in that, Includes the following steps: S1. Ingredients: Weigh the raw materials according to the mass ratio of natural bone meal: kaolin: quartz: feldspar = 1:5:2:
2. The raw materials are high-purity, pollution-free and meet the safety requirements for food contact materials. S2. Ball milling pulping: The mixed raw materials are ball milled at 300 rpm for 48 hours until the pulp fineness reaches 200 mesh, and the output is a uniform pulp without agglomeration and with good flowability; S3, Filtering, Refining, and Molding: Vacuum filter the mud until the moisture content of the mud cake is 25%±1%. After three vacuum refining processes, the mud is hydraulically molded under a pressure of 50 MPa and held for 30 seconds to obtain a uniform blank. S4. Blank treatment: Air dry naturally for 72 hours at a temperature of 25±3℃ and relative humidity of ≤60%, and lightly sand with 800-grit wet sandpaper to remove burrs; S5. High-temperature bisque firing: Heat to 1320℃ at a rate of 5℃ / minute, hold for 2 hours, and cool naturally to room temperature to obtain a ceramic embryo. S6. Embryo surface treatment: Wipe the bisque-fired body with a soft cloth or remove dust with compressed air, without mechanical polishing; S7. Base glaze sintering: Apply the base glaze by spraying, with a thickness of 0.1 mm, and keep it at 1180℃ for 1.5 hours to obtain a smooth and defect-free base glaze layer; S8. Preparation of natural selenium powder: Natural selenium-rich ore is washed with water, magnetically separated to remove impurities, acid-washed with dilute hydrochloric acid or citric acid solution to remove cadmium, ground to 300 mesh, dried and stored in a dark, sealed container. S9. Selenium-enriched glaze bonding: Selenium-enriched glaze and natural selenium powder are ball-milled together for 2 hours at a mass ratio of 10:1 to prepare a selenium-enriched glaze slurry. The glaze is sprayed with a thickness of 0.15 mm and kept at 1180℃ for 2 hours to allow the glaze layer to melt and encapsulate selenium elements to form a stable slow-release structure. S10. Finished Product Inspection: Inspect appearance, physical properties and food safety indicators, and isolate and handle unqualified products. S11. Post-processing and packaging: Wash with deionized water, sterilize with ultraviolet light or ≥120℃ high-temperature steam for 30 minutes, and then package aseptically for food grade.
5. The method for preparing a selenium-enriched ceramic with slow-release selenium element according to claim 4, characterized in that, Grind to 300 mesh in S8 to prevent selenium from volatilizing.
6. The method for preparing a selenium-enriched ceramic with slow-release selenium element according to claim 4, characterized in that, Finished product testing is conducted in accordance with GB 4806.4-2016 and GB / T 3532-2022, with selenium migration controlled between 0.01-0.06 mg / L.