Non-ferrous metallurgy · 2026-10-27
Magnesia-chrome and magnesia-alumina-chrome spinel in non-ferrous furnaces
From sintered and direct-bonded to fused rebonded, magnesia-chrome grades follow the severity of temperature and slag attack. Magnesia-alumina-chrome spinel resists sulphur dioxide, ferrous oxide and lead oxide, while keeping a moderate density and spalling resistance.
Non-ferrous slags often carry iron, lead and sulphur, and the temperature is high, so the working lining has long been a basic brick. Magnesia-chrome bricks are graded by bond and by raw material: sintered magnesia-chrome for lighter duties in smaller furnaces; direct-bonded magnesia-chrome, made from high-purity magnesia and chrome concentrate, formed under high pressure and sintered at high temperature, resisting heat, thermal shock and corrosion in a wider range of non-ferrous furnaces; fused semi-rebonded and fused rebonded grades raise the density and slag resistance of the fused grain still further, and are reserved for the more severe hot zones.
Magnesia-alumina-chrome composite spinel brick has periclase and synthetic magnesia-alumina spinel as its main phases, with a contribution from chrome. It resists high temperature, spalling and erosion, and stands up clearly to SO₂, FeO and PbO. At a moderate bulk density, in the reaction zone of a zinc-volatilisation kiln, it can ease the load on the rollers and allow a higher kiln speed; in reverberatory and fuming furnaces, where the temperature is high and swings widely, resistance to reduction and to spalling matters equally. If it is used as an alternative to magnesia-chrome in a high-temperature reaction zone, it is on the strength of that combination of slag and spalling resistance, not as a simple substitute.