(1) Refractories for converter
Magnesia carbon brick is used for furnace cap, tapping converter mouth, before and after the surface, weld pool and bottom; high strength magnesia carbon brick is used for trunnion and slag line. Usually the MgO content in magnesia carbon brick is 70 ~ 75%, graphite is 16 ~ 20%, bulk density is 2.8 ~ 2.9 g/cm3, compressive strength is 25 ~ 30 MPa. The elements of high strength magnesia carbon brick are the same elements as magnesia carbon brick, but its compressive strength should be 30 ~ 42 MPa.
(2) Refractories for electric furnace
Furnace hearth, furnace slope and molten pool are overall rammed with magnesia clinker, or constructed with magnesia brick which is made of magnesia carbon brick and tar asphalt; high-quality magnesia carbon brick is used for hot and slag line area; magnesia brick and magnetite chrome brick are used for tapping hole and the two sides of furnace door; high alumina bricks or high alumina uncalcined brick are used for furnace cover.
(3) Refractories for UHP EAF
For permanent lining of ultra high power EAF, using magnesium stone; for furnace doorjamb, using magnesia chrome brick; for slag line, eccentric bottom and molten pool, using magnesia brick; for hot spots, furnace wall and tapping hole, using magnesia carbon brick; for furnace cover, using high alumina brick; for tapping hole filler, using high ankerite filling material.
According to the working conditions of various steel furnaces, it can be proved that the refractory material for steel making working circumstance is very bad. Therefore, whatever refractories are used, it must possess the following properties.
(1) High temperature resistant and high refractoriness.
(2) Erosion and erosion resistance to high temperature molten steel and slag.
(3) The steelmaking furnace works discontinuously, thus requires refractory materials for furnace with good thermal shock resistance and spalling resistance.
(4) High mechanical strength, can withstand impact of furnace tilting and furnace charge loading with no damage.
Basic properties of refractory material for steel making