A PROCESS OF PRODUCING IMPROVED DOLOMITE BRICKS FOR USE AS LINING MATERIALS OF L.D. CONVERTERS IN STEEL PLANTS

摘要

The invention provides a process of producing dolomite bricks of improved quality for lining L.D. converters in steel plants, comprising the following steps : (a) granulating sintered dolomite/magnesia to produce grains of size 0 to 8 mm; (b) preparing the optimum batch composition containing grains of different sizes—(by. weight %) as :-5.0 to 8.0 mm - 15, 3.0 to 5.0 mm - 17, 1.6 to 3.0 mm - 20, 0.5 to 1.6 nm - 13 and 0 to 0.3 nm (containing 60% of grains smaller than 0.06 nm) - 35; (c) dividing the grains into "coarse" grains of size 0.5 to 8.0 nm and "fine" grains of size 0 to 0.3 nm; (d) mixing the coarse and fine grains in the weight ratio of 65 : 35; ,(e) heating the coarse grains in a grain heater to a temperature of 160-200°C; (f) preparing molten pitch by heating solid pitch by means of a thermic oil heating medium system at a temperature of 3000C; (g) mixing hot coarse grains with molten pitch of 5.0-5.5% by weight of total mix in the bricks; (h) pressing the mix of hot coarse grains, molten pitch and cold fine grains at a pressure of 1100-1200 kg/cm2 and temperature of 100-110°C; and (i) tempering the green bricks in the optimum schedule comprising: fast heating in a closed chamber to a temperature of 180-230°C for 1 hour, slow heating by maintaining the temperature at 280-325° C for 7 hours and slow cooling to 80-90°C in 11 hours.