Alumina residue, obtained as byproduct in the reclaiming of aluminium metal from its scrap, was determined to be useful as raw material of alumina cement. But the large content of magnesia (about 3-8%), aluminium nitride (about 3-10%) and metallic aluminium (about 5-15%) are the disadvantageous points to make alumina cement of good quality by the ordinary electric melting process. In the present paper, these disadvantageous points were skilfully eliminated by (1) mixing the alumina residue with quick or slaked lime and ferric oxide containing raw material, kneading with water and decomposing these aluminium nitride and metal, and (2) by sintering to 1300-1400°C, without melting, and the spicial alimina cement of good quality was obtained by grinding the high aluminous clinker thus produced.
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