In the steel industry, the linings of core equipment such as blast furnaces, converters, and ladles must endure temperatures above 1500°C every day, the scouring of molten iron, and the erosion of alkaline slag. There are not many refractory materials capable of withstanding such harsh conditions, and magnesia-alumina spinel bricks are among the "top performers". In recent years, more and more steel mills have replaced traditional magnesite-chrome bricks with this product. What specific outstanding advantages does it possess?
1. Strong resistance to basic slag erosion and longer service life: Slags generated in steel furnaces are mostly alkaline. When conventional magnesia-chrome bricks contact basic slag, chemical reactions easily occur and cause brick pulverization. The spinel crystal structure inside magnesia-alumina spinel bricks is stable. It can form a dense protective layer with basic slag to block slag penetration, delivering a service life 30%-50% longer than magnesia-chrome bricks.
2. Excellent thermal shock resistance, low cracking tendency: During tapping and charging operations of steel furnaces, temperature fluctuates sharply (dropping rapidly from 1600℃ to 1000℃). Traditional refractory bricks tend to crack due to thermal expansion and contraction. This product features a low thermal expansion coefficient (around 7×10⁻⁶/℃), which is 80% of that of magnesia-chrome bricks. It can withstand drastic temperature changes, with the cracking rate reduced by over 60%.
3. Chrome-free & eco-friendly, complying with green production requirements
Conventional magnesia-chrome bricks contain hexavalent chromium, which contaminates soil and water after disposal. Magnesia-alumina spinel bricks are chrome-free environmental refractories without pollution, matching the trend of "green production" in the steel industry.
To fully exert the material's performance, the following points should be noted during application:
For bricklaying, magnesia refractory mortar must be adopted instead of high-alumina mortar to avoid joint cracking caused by material incompatibility. The mortar joint thickness shall be controlled uniformly within 1–2 mm. Excessively thick joints allow slag infiltration to damage the lining, while uneven thickness leads to unbalanced stress and local spalling;Maintain regular inspections. Check the condition of the lining after each steel discharge. Fill minor cracks less than 3mm with magnesia repair material, repair small areas of spalling with refractory plastic, and promptly replace large areas of damage to prevent defects from continuing to expand and causing accidents.
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