Tar-Bonded Dolomite Refractory

any of the materials formed by pressing calcined dolomite powder (grain size up to 6–8 mm) that has been mixed upon heating to 100°-120°C with 4–6 percent coal tar or pitch. Tar-bonded dolomite refractories have an apparent density of 2,800–2,900 kg/m³ and a compressive strength of 20–40 meganewtons/m² (200–400 kilograms-force/cm²). They are resistant to basic slags. Additions of magnesite powder yield materials known as tar-bonded dolomite magnesite refractories. The free CaO present in large amounts in tar-bonded dolomite refractories is hydrated upon exposure to air. The resistance of the refractories to hydration increases after heat treatment at 300°-350°C in a reducing environment.

Tar-bonded dolomite refractories are used for lining oxygen converters; gaps in these converters are filled with a mixture known as tar-bonded dolomite substance, whose composition is analogous to that of the refractories. The refractories are sometimes used for lining electric arc steelmaking furnaces.