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What are magnesia alumina spinel brick?
Magnesia alumina spinel brick is a high-performance refractory material, mainly composed of magnesium oxide (มก) and aluminum oxide (อัล2O3), which is made by artificial synthesis3. This brick is very rare in nature, so the magnesia alumina spinel bricks in industrial applications are obtained by artificial synthesis.
Other magnesia-containing refractory bricks
Main ingredients and preparation
Alumina (อัล2O3): The content is usually above 76%;
Magnesia (มก): The content is usually above 95%;
These components are sintered at a high temperature of more than 1800°C in an ultra-high temperature tunnel kiln through a multi-stage homogenization process.
Magnesia alumina spinel brick
Physical and chemical indicators of magnesia alumina spinel
| Physical and chemical indicators | Numeric |
|---|---|
| MgO content | ≥82% |
| Al2O3 content | 13-15% |
| SiO2 content | ≤0.7% |
| CaO content | ≤1.3% |
| Fe2O3 content | ≤0.8% |
| Bulk density | ≥2.98 g/cm³ |
| Apparent porosity | ≤17% |
| Normal temperature compressive strength | ≥60 MPa |
| โหลดอุณหภูมิเริ่มต้นอ่อนตัว | ≥1700°C |
| เสถียรภาพการกระแทกจากความร้อน | ≥15次（1100°C Water Cooling） |
| การหักเหของแสง | ≥1800°C |
From Wikipedia：Periclase、Refractory
Please note that when selecting magnesia-alumina spinel bricks, the required physical and chemical indicators should be determined according to the specific conditions of use and requirements.
Main parameters
- เสถียรภาพการกระแทกจากความร้อน: Magnesia alumina spinel bricks have good thermal shock stability and can withstand 20~25 times of water cooling and more than 100 times of air cooling.
- Erosion resistance: Magnesia aluminate spinel bricks have strong resistance to alkaline slag and iron oxide slag, and their ability to protect periclase particles from slag erosion is stronger than that of calcium magnesium olivine.
- Anti-stripping performance: Magnesia aluminate spinel bricks will react with clinker during use, forming a very thin calcium aluminate protective layer on the surface of the brick, making their anti-stripping performance better than that of directly bonded magnesia chrome bricks.
- Thermal expansion coefficient: Since both magnesium aluminate spinel and periclase belong to the cubic crystal system, the thermal expansion along each crystal axis is the same, so the expansion and contraction are relatively uniform when the temperature fluctuates, and the thermal stress generated is small.
Price of magnesia spinel bricks
The price ranges from 200 yuan to 9,300 yuan, depending on the supplier and product specifications.
What is magnesium aluminate spinel used for?
เตาเผาแบบหมุนปูนซีเมนต์: used in high temperature zones, replacing traditional magnesia chrome bricks to avoid chromium pollution.
การถลุงเหล็ก: used to make ladle lining bricks and ladle castables to improve the erosion resistance of steel plate linings.
Glass industry kiln: used in high temperature areas to ensure efficient operation of the kiln.
Precautions for magnesia alumina spinel bricks
ความต้านทานการกัดกร่อน: In some corrosive environments, its corrosion resistance may not be as good as that of directly bonded magnesia chrome bricks.
Hydration problem: Sintered spinel bricks are easy to hydrate, which may cause volume changes, so be careful when using them.
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