In the hierarchy of magnesia materials, while Fused Magnesia (as discussed in our previous article) is the king of purity and crystal size, High-Purity Sintered Magnesia (HPSM) is the industry’s reliable workhorse. HPSM, also known as Dead Burned Magnesia (DBM), forms the essential foundation for most high-performance magnesia-based refractory products worldwide.
What is Sintered Magnesia?
Sintered Magnesia is produced through a thermal process known as sintering. High-purity natural magnesite or chemically purified magnesium hydroxide is first calcined (light-burned) to form active
These briquettes are then fired in ultra-high-temperature kilns, such as shaft kilns or rotary kilns, at temperatures ranging from 1750°C to 2000°C. This intense heat causes the particles to densify, reducing porosity and promoting the growth of periclase crystals, resulting in the final, stable, and highly dense product known as DBM.
The Critical Difference: Fused vs. Sintered
While both HPSM and Fused Magnesia are essential refractory materials, their production method leads to distinct applications:
| Feature | High-Purity Sintered Magnesia (HPSM) | Large Crystal Fused Magnesia (LCFM) |
| Production Temp. | 1750°C – 2000°C (Kiln) | Over 3000°C (Electric Arc Furnace) |
| Purity (MgO) | Generally 96% – 98% | Typically 97.5% – 99% |
| Crystal Size | Fine to Medium Grains (50 – 200 µm) | Large, Well-Developed Crystals (200 – 1000 µm) |
| Primary Use | Refractory bricks, castables, and gunning mixes. | Slag line bricks, critical components requiring ultimate stability. |
Key Performance Advantages
HPSM is indispensable due to its balance of cost-effectiveness and performance:
- Excellent High-Temperature Volume Stability: The high firing temperature eliminates volume shrinkage at application temperatures, which is critical for maintaining the structural integrity of furnace linings.
- High Bulk Density and Low Porosity: A density often exceeding 3.30 g/cm³ and extremely low open porosity grant the material resistance against thermal shock and alkali/slag penetration.
- Cost-Efficiency: Compared to the energy-intensive fusion process, sintering offers a more economical pathway to high-purity material, making it accessible for large-volume applications.
Primary Applications
High-Purity Sintered Magnesia is the workhorse in major industrial sectors:
- Magnesia Bricks (e.g., Magnesia-Chrome, Magnesia-Alumina): It is the main component for manufacturing various shapes of sintered magnesia bricks used in steel ladle permanent linings, non-ferrous smelting furnaces, and transition zones of cement kilns.
- Monolithic Refractories: Used as an aggregate in high-grade ramming mixes, gunning mixes, and castables for patching and maintaining furnace linings.
Conclusion
High-Purity Sintered Magnesia remains vital for any operation demanding durability and efficiency at high temperatures. By balancing high performance with superior volume stability and cost-effectiveness, HPSM ensures your refractory linings can withstand the most rigorous industrial demands.