Anti-scouring composite ceramic for furnace bottom discharge hole of high radioactive nuclide glass curing smelting furnace

Abstract

The invention belongs to the technical field of ceramic materials for nuclear waste treatment, and discloses an anti-scouring composite ceramic for a furnace bottom discharge port of a high radioactive nuclide glass curing smelting furnace, which is characterized in that chromium oxide is added with nanoscale zirconium oxide and a binding agent, and a chromium-zirconium sintered body with high density and ultralow porosity is prepared by a spray granulation method; the titanium-aluminum-chromium-zirconium composite ceramic which is ultralow in porosity and high in elasticity modulus is prepared by introducing aluminum titanate ceramic powder, clay, sodium bentonite and aluminum sol to be combined, performing hydraulic forming through a volumetric method and performing high-temperature sintering, is excellent in strong thermal shock resistance and scouring resistance, is applied to a furnace bottom discharge port lining of a high-emission nuclide glass curing smelting furnace, and can be used for manufacturing a high-emission nuclide glass curing smelting furnace. And the service life of the discharge hole of the high-level radioactive nuclide glass curing smelting furnace is effectively prolonged.

Description

Technical Field

[0001] This invention belongs to the technical field of ceramic materials for nuclear waste treatment furnaces, specifically relating to an anti-erosion composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace. Background Technology

[0002] Nuclear waste is characterized by high concentrations of radioactive elements, high heat release rates, and strong corrosiveness. Vitrification technology is currently the only industrially applicable technology for treating high-level radioactive waste. It involves mixing and melting high-level radioactive waste with glass raw materials, then cooling to form a glass body. The glass body has a low leaching rate and high strength, and the high-level radioactive nuclides are contained within a stable glass substrate. This effectively contains radioactive materials and forms a stable morphology, thus converting the waste into a solid, which greatly improves the safety of storage and meets the requirements for long-term stable storage of high-level radioactive waste.

[0003] The glass curing furnace is the core equipment in high-level radioactive waste glass curing technology. The discharge method of the glass curing furnace is bottom discharge. During the service process, the discharge port is subjected to high and low temperature fatigue for a long time. In addition, the repeated melting and curing process of the glass curing material in the discharge port will also repeatedly apply external forces to the discharge port, which will easily cause erosion and damage to the refractory material at the discharge port. This will inevitably affect the entire high-level radioactive waste glass curing process. In view of the harsh operating environment of the discharge port, it is urgent to develop a composite ceramic for the discharge port of the electrically heated ceramic furnace for high-level radioactive waste glass curing to improve its performance and service life. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an anti-erosion composite ceramic for the bottom outlet of a high-radioactive glass-curing furnace. A highly dense, ultra-low porosity chromium-zirconium sintered body is prepared using a spray granulation method. Then, aluminum titanate ceramic powder, clay, sodium bentonite, and alumina sol are introduced and combined, followed by hydraulic molding and high-temperature sintering to produce a titanium-alumina-chromium-zirconium composite ceramic with ultra-low porosity and high elastic modulus. When applied to the lining of the bottom outlet of a high-radioactive glass-curing furnace, it exhibits strong thermal shock resistance and erosion resistance, effectively extending the service life of the furnace outlet.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an anti-erosion composite ceramic for the bottom outlet of a high radionuclide glass curing furnace, wherein the raw material comprises the following components by weight: 85-90 parts of chromium zirconium sintered granules, 4-5 parts of aluminum titanate ceramic powder, 1 part of clay, 0.5 parts of sodium-based bentonite, and 3 parts of aluminum sol.

[0006] The aluminum sol contains 40% alumina solids, 20% organosilicon resin, and 40% deionized water.

[0007] The raw material components of the chromium-zirconium sintered granulation material include, by weight, 90 parts of chromium oxide, 10 parts of nano-zirconium oxide powder, plus 31% of deionized water, 3% isopropanol and 1% polyvinyl acetal, accounting for 31% of the total weight of the raw material.

[0008] The chromium oxide particles are 325 mesh.

[0009] The solid content of polyvinyl acetal is ≥65%.

[0010] The preparation of chromium zirconium sintered granules by spray granulation includes the following steps: (1) Chromium oxide and nano-sized zirconium oxide powder are added to a ball mill in proportion, and then deionized water is added. The slurry is ball-milled for 36 hours. (2) After the slurry is finely ground, isopropanol and polyvinyl acetal are added while forcibly stirring to obtain a mixed slurry. The viscosity of the mixed slurry is controlled at 400 Pa·s. (3) After vacuum degassing, the mixed slurry is added to a centrifugal spray granulator for spray granulation. The high-speed centrifugal rotating spray disc is used for atomization spraying to form small droplet spheres of 80-100 μm. At the same time, it is instantaneously dried with hot air at 300-350℃. (4) The dried particles are blown to a separator with hot air for gas separation and sieving to obtain spherical granules. (5) The spherical granules are sintered in a high-temperature vertical kiln at 2250-2350℃ to form chromium zirconium sintered granules with high density and ultra-low porosity.

[0011] The method for preparing erosion-resistant composite ceramics for the bottom outlet of a high-radioactive nuclide glass curing furnace by volumetric static pressing includes the following steps: (1) Preparing alumina sol as a binder, first mixing alumina with deionized water evenly, then adding silicone resin and stirring thoroughly; (2) Mixing chromium zirconium sintered granules, aluminum titanate ceramic powder, clay, and sodium bentonite in proportion, then forcibly stirring, then adding the prepared alumina sol as a binder and mixing evenly to form a mixed blank; (3) Using a 4000t hydraulic press isostatic pressing method. The mixed blanks are pressed into block ceramic blanks with a molding pressure of 150-200MPa and a static pressure of 60-160s; (4) The ceramic blanks are placed in a drying furnace and dried at 100-150℃ for 24h. Then the dried ceramic blanks are placed in a high-temperature tunnel kiln for firing. The temperature is raised to 500℃ at a rate of 0.5-2℃ / min and held for 2-5h. Then the temperature is raised to 1750-1800℃ at a rate of 2-5℃ / min and fired for 6 hours to obtain titanium-aluminum-chromium-zirconium composite ceramics.

[0012] This invention produces highly dense, ultra-low porosity chromium-zirconium sintered granules using a spray granulation method. These granules are then combined with aluminum titanate ceramic powder, clay, sodium bentonite, and alumina sol. The mixture is then hydraulically formed using a volumetric method and sintered at high temperature to produce a titanium-aluminum-chromium-zirconium composite ceramic material with ultra-low porosity and high elastic modulus. This improves the overall thermal shock resistance, erosion resistance, and corrosion resistance of the ceramic material. The normal operating temperature of this composite ceramic is 900-1000℃, which is below the temperature range where aluminum titanate decomposes at 1000-1200℃. The addition of aluminum titanate enhances the thermal shock resistance of the composite ceramic.

[0013] The centrifugal spray granulator operates by passing air through a filter and heating device before it enters a hot air distributor at the top of the drying chamber. The hot air is evenly distributed within the drying chamber and rotates in a spiral pattern, simultaneously delivering the mixed slurry to a centrifugal spray disc located at the top of the drying chamber. The slurry is atomized into extremely small droplets, significantly increasing the surface area of ​​contact between the slurry and the hot air, allowing for rapid evaporation of moisture and drying of the finished product in a very short time. In this invention, the spray granulation method for preparing chromium-zirconium sintered granules employs a vacuum degassing process during slurry preparation. This aims to reduce the number of tiny air bubbles in the slurry, ensuring uniformity and forming highly dense, ultra-low porosity granular particles. These particles are then sintered at high temperature to form the chromium-zirconium sintered granules.

[0014] In addition, during the production of ceramic materials, the addition of chromium-zirconium sintering granules in the form of spherical granules has better dispersibility and flowability, greatly improves the toughness of composite ceramics, reduces the sintering temperature, and changes the properties of ceramic materials.

[0015] The beneficial effects of this invention are as follows: The titanium-aluminum-chromium-zirconium composite ceramic material prepared by this invention has ultra-low porosity and high elastic modulus, which can resist the damage to the furnace outlet accelerated by radiation and irradiation heating of highly radioactive and toxic nuclides such as cesium-137, strontium-90, and plutonium-239; it can resist the erosion of molten borosilicate glass, and in particular, it will not produce a low-melting phase of sodium aluminosilicate with borosilicate glass; its strong thermal shock resistance can resist the long-term high and low temperature fatigue of the outlet during service, and the repeated melting and solidification process of the glass curing material in the outlet will also repeatedly apply external force to the outlet, resisting erosion damage; when applied to the inner lining of the outlet of the furnace bottom of a high-radioactive nuclide glass curing furnace, it has a long service life. Attached Figure Description

[0016] Figure 1 The crystal phase diagram is shown for the titanium-aluminum-chromium-zirconium composite ceramic prepared in Example 1 of this invention.

[0017] In the diagram: Mark 1 is Mark 2 as Mark 3 as Vitreous body. Detailed Implementation

[0018] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0019] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are conventional methods; and the reagents and materials used are commercially available unless otherwise specified.

[0020] The particle size of chromium oxide is 325 mesh; the solid content of polyvinyl acetal is ≥65%; the solid content of alumina in the aluminum sol is 40%, the solid content of organosilicon resin is 20%, and the solid content of deionized water is 40%.

[0021] Example 1:

[0022] An anti-erosion composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace, the raw material comprises the following components by weight: 88 parts of chromium zirconium sintered granules, 4.5 parts of aluminum titanate ceramic powder, 1 part of clay, 0.5 parts of sodium-based bentonite, and 3 parts of aluminum sol.

[0023] The raw material composition of the chromium-zirconium sintered granulation material includes, by weight, 90 parts of chromium oxide, 10 parts of nano-sized zirconium oxide powder, plus 31% of deionized water, 3% of isopropanol and 1% of polyvinyl acetal, accounting for 31% of the total weight of the raw material.

[0024] The preparation of chromium zirconium sintered granules by spray granulation includes the following steps: (1) Chromium oxide and nano-sized zirconium oxide powder are added to a ball mill in proportion, and then deionized water is added. The slurry is ball-milled for 36 hours. (2) After the slurry is finely ground, isopropanol and polyvinyl acetal are added while forcibly stirring to obtain a mixed slurry. The viscosity of the mixed slurry is controlled at 400 Pa·s. (3) After vacuum degassing, the mixed slurry is added to a centrifugal spray granulator for spray granulation. The high-speed centrifugal rotating spray disc is used for atomization spraying to form small droplet spheres of 80-100 μm. At the same time, it is instantaneously dried with hot air at 350℃. (4) The dried particles are blown to a separator with hot air for gas separation and sieving to obtain spherical granules. (5) The spherical granules are sintered in a high-temperature vertical kiln at 2300℃ to form chromium zirconium sintered granules with high density and ultra-low porosity.

[0025] A method for preparing erosion-resistant composite ceramics for the bottom outlet of a high-radioactive nuclide glass curing furnace using volumetric static pressing includes the following steps: (1) Preparing aluminum sol as a binder, first mixing alumina with deionized water evenly, then adding silicone resin and stirring thoroughly; (2) Mixing chromium zirconium sintered granules, aluminum titanate ceramic powder, clay, and sodium bentonite in proportion, then forcibly stirring, then adding the prepared aluminum sol as a binder and mixing evenly to form a mixed blank; (3) Using 400 The 0t hydraulic press isostatic pressing method is used to press the mixed blank into a block ceramic blank. The forming pressure is 200MPa and the static pressure is 160s. (4) The ceramic blank is placed in a drying furnace and dried at 120℃ for 24h. Then the dried ceramic blank is placed in a high-temperature tunnel kiln for firing. The temperature is raised to 500℃ at a rate of 1℃ / min and held for 3h. Then the temperature is raised to 1800℃ at a rate of 3℃ / min and fired for 6 hours to obtain titanium aluminum chromium zirconium composite ceramic.

[0026] Example 2:

[0027] An anti-erosion composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace, the raw material comprises the following components by weight: 85 parts of chromium zirconium sintered granules, 4 parts of aluminum titanate ceramic powder, 1 part of clay, 0.5 parts of sodium-based bentonite, and 3 parts of aluminum sol.

[0028] The raw material composition of the chromium-zirconium sintered granulation material includes, by weight, 90 parts of chromium oxide, 10 parts of nano-sized zirconium oxide powder, plus 31% of deionized water, 3% of isopropanol and 1% of polyvinyl acetal, accounting for 31% of the total weight of the raw material.

[0029] The preparation of chromium zirconium sintered granules by spray granulation includes the following steps: (1) Chromium oxide and nano-sized zirconium oxide powder are added to a ball mill in proportion, and then deionized water is added. The slurry is ball-milled for 36 hours. (2) After the slurry is finely ground, isopropanol and polyvinyl acetal are added while forcibly stirring to obtain a mixed slurry. The viscosity of the mixed slurry is controlled at 400 Pa·s. (3) After vacuum degassing, the mixed slurry is added to a centrifugal spray granulator for spray granulation. The high-speed centrifugal rotating spray disk is used for atomization spraying to form small droplet spheres of 80-100 μm. At the same time, it is instantaneously dried with hot air at 300℃. (4) The dried particles are blown to a separator with hot air for gas separation and sieving to obtain spherical granules. (5) The spherical granules are sintered in a high-temperature vertical kiln at 2250℃ to form chromium zirconium sintered granules with high density and ultra-low porosity.

[0030] A method for preparing erosion-resistant composite ceramics for the bottom outlet of a high-radioactive nuclide glass curing furnace using volumetric static pressing includes the following steps: (1) Preparing aluminum sol as a binder, first mixing alumina with deionized water evenly, then adding silicone resin and stirring thoroughly; (2) Mixing chromium zirconium sintered granules, aluminum titanate ceramic powder, clay, and sodium bentonite in proportion, then forcibly stirring, then adding the prepared aluminum sol as a binder and mixing evenly to form a mixed blank; (3) Using 400 The mixed blanks were pressed into block ceramic blanks by isostatic pressing method using a 0t hydraulic press. The molding pressure was 150MPa and the static pressure was 60s. (4) The ceramic blanks were placed in a drying furnace and dried at 100℃ for 24h. Then the dried ceramic blanks were placed in a high-temperature tunnel kiln for firing. The temperature was raised to 500℃ at a rate of 0.5℃ / min and held for 2h. Then the temperature was raised to 1750℃ at a rate of 2℃ / min and fired for 6 hours to obtain titanium aluminum chromium zirconium composite ceramics.

[0031] Example 3:

[0032] An anti-erosion composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace, the raw material comprises the following components by weight: 90 parts of chromium zirconium sintered granules, 5 parts of aluminum titanate ceramic powder, 1 part of clay, 0.5 parts of sodium-based bentonite, and 3 parts of aluminum sol.

[0033] The raw material composition of the chromium-zirconium sintered granulation material includes, by weight, 90 parts of chromium oxide, 10 parts of nano-sized zirconium oxide powder, plus 31% of deionized water, 3% of isopropanol and 1% of polyvinyl acetal, accounting for 31% of the total weight of the raw material.

[0034] Chromium-zirconium sintered granules were prepared by spray granulation, including the following steps: (1) Chromium oxide and nano-sized zirconium oxide powder were added to a ball mill in proportion, and then deionized water was added. The slurry was ball-milled for 36 hours. (2) After the slurry was finely ground, isopropanol and polyvinyl acetal were added while forcibly stirred to obtain a mixed slurry. The viscosity of the mixed slurry was controlled at 400 Pa·s. (3) After vacuum degassing, the mixed slurry was added to a centrifugal spray granulator for spray granulation. The high-speed centrifugal rotating spray disk was used for atomization spraying to form small droplet spheres of 80-100 μm. At the same time, the spheres were instantly dried with hot air at 320℃. (4) The dried granules were blown to a separator with hot air for gas separation and sieving to obtain spherical granules. (5) The spherical granules were sintered in a high-temperature vertical kiln at 2350℃ to form chromium-zirconium sintered granules with high density and ultra-low porosity.

[0035] A method for preparing erosion-resistant composite ceramics for the bottom outlet of a high-radioactive nuclide glass curing furnace using volumetric static pressing includes the following steps: (1) Preparing aluminum sol as a binder, first mixing alumina with deionized water evenly, then adding silicone resin and stirring thoroughly; (2) Mixing chromium zirconium sintered granules, aluminum titanate ceramic powder, clay, and sodium bentonite in proportion, then forcibly stirring, then adding the prepared aluminum sol as a binder and mixing evenly to form a mixed blank; (3) Using 400 The 0t hydraulic press isostatic pressing method is used to press the mixed blank into a block ceramic blank. The forming pressure is 180MPa and the static pressure is 100s. (4) The ceramic blank is placed in a drying furnace and dried at 150℃ for 24h. Then the dried ceramic blank is placed in a high-temperature tunnel kiln for firing. The temperature is raised to 500℃ at a rate of 2℃ / min and held for 5h. Then the temperature is raised to 1780℃ at a rate of 5℃ / min and fired for 6 hours to obtain titanium aluminum chromium zirconium composite ceramic.

[0036] The main chemical compositions of the titanium-aluminum-chromium-zirconium composite ceramics prepared in Examples 1-3 are shown in the table below:

[0037]

[0038] The main performance indicators of the titanium-aluminum-chromium-zirconium composite ceramics prepared in Examples 1-3 are shown in the table below:

[0039]

[0040] The test data in the table above shows that the main chemical components of the prepared titanium-aluminum-chromium-zirconium composite ceramic are: alumina 3-4%, chromium oxide 84-86%, zirconia 8%, titanium oxide 2%, silicon dioxide and others 1.5%.

[0041] The main performance indicators of the prepared titanium-aluminum-chromium-zirconium composite ceramics are: bulk density Elastic modulus 220-280 GPa; Thermal conductivity at 1000℃ 3.0-3.1 W / (m·K); Coefficient of thermal expansion at 1000℃ Thermal shock resistance: 10 cycles (DIN standard, water-cooled).

[0042] Depend on Figure 1 It can be seen that at high-temperature sintering temperatures, a structure is formed... , As the skeleton, with The solid-state equilibrium relationship where the glassy phase acts as a binder, i.e., chromium trioxide ( Zirconium dioxide (ZrO2) ) and aluminum-titanium-silicon ternary oxide glass ( A multiphase titanium-aluminum-chromium-zirconium ceramic system composed of a glassy body.

[0043] The titanium-aluminum-chromium-zirconium composite ceramic material prepared by this invention has ultra-low porosity and high elastic modulus, which can resist the damage to the furnace outlet accelerated by radiation and irradiation heating of highly radioactive and toxic nuclides such as cesium-137, strontium-90, and plutonium-239. Its strong thermal shock resistance can resist the fatigue of the outlet under high and low temperature conditions during long-term service. In addition, the repeated melting and solidification process of the glass curing material in the outlet will also repeatedly apply external forces to the outlet, resisting erosion damage. When applied to the inner lining of the outlet of the furnace bottom of a high-radioactive nuclide glass curing furnace, it has a long service life.

[0044] The specific embodiments of the present invention have been described in detail above with reference to the examples, but the scope of protection of the present invention should not be limited thereto. The present invention is not limited to the above embodiments, and any changes made within the scope of protection of the claims of the present invention are within the scope of protection of the present invention.

Claims

1. An erosion-resistant composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace, characterized in that, The raw materials include the following components by weight: 85-90 parts of chromium zirconium sintered granules, 4-5 parts of aluminum titanate ceramic powder, 1 part of clay, 0.5 parts of sodium-based bentonite, and 3 parts of aluminum sol. The raw material composition of the chromium zirconium sintered granulation material includes, by weight, 90 parts of chromium oxide, 10 parts of nano-sized zirconium oxide powder, plus 31% of deionized water, 3% of isopropanol and 1% of polyvinyl acetal, accounting for 31% of the total weight of the raw material. Chromium-zirconium sintered granules were prepared by spray granulation and titanium-aluminum chromium-zirconium composite ceramics were prepared by volumetric static pressing. The main chemical composition of the ceramics was: alumina 3-4%, chromium oxide 84-86%, zirconium oxide 8%, titanium oxide 2%, silicon dioxide and others 1.5%.

2. The erosion-resistant composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace according to claim 1, characterized in that: The particle size of chromium oxide is 325 mesh.

3. The erosion-resistant composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace according to claim 1, characterized in that: The solid content of polyvinyl acetal is ≥65%.

4. The erosion-resistant composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace according to claim 1, characterized in that: The aluminum sol contains 40% alumina solid solution, 20% organosilicon resin, and 40% deionized water.

5. The erosion-resistant composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace according to claim 1, characterized in that, The preparation of chromium zirconium sintered granules by spray granulation includes the following steps: (1) Chromium oxide and nano-sized zirconium oxide powder are added to a ball mill in proportion, and then deionized water is added. The slurry is ball-milled for 36 hours. (2) After the slurry is finely ground, isopropanol and polyvinyl acetal are added while forcibly stirring to obtain a mixed slurry. The viscosity of the mixed slurry is controlled at 400 Pa·s. (3) After vacuum degassing, the mixed slurry is added to a centrifugal spray granulator for spray granulation. The high-speed centrifugal rotating spray disc is used for atomization spraying to form small droplet spheres of 80-100 μm. At the same time, it is instantaneously dried with hot air at 300-350℃. (4) The dried particles are blown to a separator with hot air for gas separation and sieving to obtain spherical granules. (5) The spherical granules are sintered in a high-temperature vertical kiln at 2250-2350℃ to form chromium zirconium sintered granules with high density and ultra-low porosity.

6. The erosion-resistant composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace according to claim 1, characterized in that, The preparation of erosion-resistant composite ceramics for the bottom outlet of a high-radioactive glass curing furnace by volumetric static pressing includes the following steps: (1) Prepare aluminum sol as a binder, first mix alumina and deionized water evenly, then add silicone resin and stir thoroughly; (2) Mix chromium zirconium sintered granules, aluminum titanate ceramic powder, clay, and sodium bentonite in proportion, force stir, then add the prepared aluminum sol as a binder and mix evenly to form a mixed blank; (3) Press the prepared mixed blank into a block ceramic blank using a 4000t hydraulic press isostatic pressing method; (4) Place the ceramic blank in a drying furnace and dry it at 100-150℃ for 24h, then place the dried ceramic blank in a high-temperature tunnel kiln for firing to obtain titanium aluminum chromium zirconium composite ceramics.

7. The erosion-resistant composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace according to claim 6, characterized in that: In step (3), the hydraulic forming pressure of the ceramic blank is 150-200MPa, and the static pressure is 60-160s.

8. The erosion-resistant composite ceramic for the bottom outlet of a high-radioactive nuclide glass curing furnace according to claim 6, characterized in that, In step (4), the temperature is increased to 500℃ at a rate of 0.5-2℃ / min, and held for 2-5 hours. Then the temperature is increased to 1750-1800℃ at a rate of 2-5℃ / min and fired for 6 hours.

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