Shaped Carbon-Bearing Magnesia and Doloma Refractories for the Steel Industry

摘要

Magnesia - and doloma-carbon briquettes were processed from graded dead-burned Chinese magnesite and Egyptian dolomite. From 10 to 20 percent flaky graphite as a source of carbon, as well as suitable amounts of pitch, resole phenolic resin as carbonaceous bond and Al-met-al as antioxidant were selected for processing these briquettes. The oxidation resistance, den-sification parameters and cold crushing strength of the processed briquettes were assessed in relation to their solid-phase composition and mi-crostructure after firing at up to 1500 deg C in a reducing atmosphere. It is concluded thatthe cold crushing strength is maximized aftertempering magnesia- and doloma-C briquettes at 200 deg C and then slightly reduced on firing at up to 1000 deg C in reducing atmosphere. This is correlated to the polymerization of pitch / resoles ingredients into fine hollow fibres, which persists up to 1500 deg C. On increasing the flaky graphite content from 10 percent to between 15 and 20 percent, a noticeable appreciable decrease in bulk density occurs along with increasing apparent porosity after firing at up to 1500 deg C in a reducing atmosphere.