In continuing the previous studies (This Journal, 60 No. 668, p. 60-65 and No. 676, p. 422-425 (1952); 61 No. 682, p. 152-154 (1953)), the present authors reported in the present paper, the results of further studies on the chromite-magnesia refractories by using chromite ore and special sea-water magnesia clinker obtained by dead burning special magnesium hydroxide contained a few percents of ferric oxide, which was specially obtained from dilute bittern solution by settling with slaked dolomite slurry from calcined dolomite with 3-5% limonite powder.
Among many comparative testings, the best result was obtained as one of the example, having, the following phisical properties and chemical compositions: True density: 3.86, Aparent density: 3.83, Volume density: 2.90, Perosity: 24.1%, Water absorption: 8.3%, Compressive strength: 420kg/cm², SiO₂: about 8%, Al₂O₃: about 12%, Fe₂O₃: about 15%, CaO: about 3%, MgO: about 32% and Cr₂O₃: about 32%. But these contents of SiO₂, Al₂O₃ and Fe₂O₃ are a little too large owing to the low grade of chromite ore, and the content of CaO is a little too large owing to the high lime content of sea-water magnesia clinker.