A scaffold is an unwanted crust or bridge of semi-molten ore, slag, and coke that adheres to the refractory lining above the tuyeres. It disrupts the downward flow of the burden and the upward flow of reducing gases. If a scaffold grows too large, it can cause the furnace to hang and eventually slip, dropping a massive cold chunk into the hearth.
Heard on the job
The pressure drop across the stack tells me we're building a scaffold on the north wall.
Also heard as
- scaffolding
- bridge