Strip-out by excavator or by hand: criteria for the demolition method

Stripping out the old lining is the least spectacular part of a complete relining — and the part that decides the schedule. Done too cautiously, it eats up the overhaul window. Done too roughly, it damages the furnace structure and creates rework that only becomes visible during relining. We have stripped out old linings both mechanically with an excavator and by hand — the choice is not made by preference, but by four criteria.

Four questions before the first blow

• What is the accessibility like? An excavator needs an access route and working space. On a cupola furnace in cramped conditions it is ruled out, no matter how much faster it would be.
• What will the structure carry? The shell and the load-bearing components have to absorb the forces introduced. Where that is unclear, the first step is to check, not to demolish.
• How many cubic metres are involved? With large volumes, deploying machinery pays for itself quickly. For individual zones, the set-up time is greater than the time saved.
• Do materials have to be separated by type? If materials are to be collected separately for disposal or recovery, the hand works more precisely than the bucket.