Andalusite
Aluminosilicate mineral that mullitises directly on firing, giving refractories high creep and thermal-shock resistance without a separate sintering step.
Applications
- Steel ladle and tundish linings
- Blast furnace runners and troughs
- Monolithic castables and gunning mixes
- Kiln furniture and ceramic setters
Frequently Asked Questions
What makes andalusite different from other aluminosilicates?
It converts to mullite directly on firing, without passing through a liquid phase, and it does so with very little volume change. Kyanite by contrast expands substantially on mullitisation and has to be pre-calcined. That direct, low-expansion conversion is why andalusite can go into a lining raw and still give creep and thermal-shock resistance.
What grain sizes are available?
Standard fractions of 0–1, 1–3 and 3–6 mm, plus milled powder. Coarser fractions form the aggregate skeleton of a castable; the fines contribute to matrix mullitisation. Most formulations use two or three fractions together.
Does iron content matter?
Yes, significantly. Fe₂O₃ forms low-melting glassy phases at grain boundaries that undo the creep resistance the mineral is bought for. Keep it at or below 1.0% for demanding steel applications; a higher-iron grade is acceptable in lower-temperature service and costs less.