Non-ferrous metallurgy · 2026-10-28
Toughness, spalling and erosion in slag-resistant linings
The reaction zone of a non-ferrous furnace must resist slag ingress, thermal-shock spalling, and erosion by gas and burden at the same time. The damage parameter R‴ is a reminder that how much strength remains after cracking depends on whether the brick is tough enough.
In the reaction zone of a zinc-volatilisation kiln, and in the hot zones of gasifiers, reverberatory furnaces and bottom- or side-blown furnaces, failure is rarely of one kind only. Slag wants to infiltrate, the hot face must take temperature swings, and gas and burden keep eroding, building up or ringing. A brick that is only slag-resistant, and spalls quickly under thermal shock, will not stay in these furnaces.
A flexible slag-resistant brick holds corrosion resistance, spalling resistance and erosion resistance in the same microstructure: the matrix must slow the advance of slag along grain boundaries, while the aggregate and the bond absorb strain at microcracks or phase boundaries, so that a crack does not run through. Build-up and ringing change the boundary condition at the hot face and raise local stress, so resistance to ringing is not an extra demand — it is another side of the same problem.
Slag viscosity, oxygen potential and the severity of erosion differ widely from one raw material and one furnace to another. The same family of slag-resistant material will not automatically behave in the same way in a zinc leach-residue kiln, a lead-iron slag furnace or a waste incinerator. The choice starts from the slag and from the path of thermal shock, not from the assumption that one brick can cover every non-ferrous furnace.