Refractory ceramic mass and its use

Refractory ceramic mass, comprising a mixture of:

• 75 to 95 wt. % of sintered MgO, and
• 5 to 25 wt. % of a spinel of hercynite (Mg,Fe) (Fe,Al).sub.2 O.sub.4,
• in which the spinel comprises
• 45 to 50 wt. % of iron, calculated as FeO,
• 1 to 5 wt. % of MgO,
• 45 to 50 wt. % of Al.sub.2 O.sub.3, and
• <3 wt. % of impurities selected from the group consisting of SiO.sub.2, CaO, Cr.sub.2 O.sub.3, MnO, alkalies, and combinations thereof,
• in which the spinel is a sintered spinel,
• in which the sintered MgO has a particle size of <4 mm and the spinel has a particle size of <2 mm, and
• in which a portion of the sintered MgO has a particle size of <125 .mu.m, said portion consisting of 10 to 35 wt. % of the mass.