A number of cases can be distinguished:
- Unused refractory products: bricks discarded because of non-conformity or unused stocks of reserve parts.
- Used refractory products:
- For mechanical and thermal applications used refractories are relatively uncontaminated: e.g. coatings for insulation or safety….
- Under corrosive conditions: contact with molten materials (glass, metal, slag) or gases (soda, sulphates, zinc…)
- surface contamination:
- magnesia-carbon in steel plants
- sliding plates in continuous casting
- electromelting blocks in glass making,…
- deep contamination:
- silica archways and regenerators in glass making
- blast furnace linings
- alumina or magnesia – chrome, rich in hexavalent chrome