Gas supply component, also called purging plug bricks is used to blow noble gases into steel smelting vessels for steel liquid stirring. Gas blowing is an important method of modern metal smelting, is a key step of out-furnace refinery. Purging plug’s main function is strengthening smelting speed, speeding reaction process, shortening smelting time, homogenizing steel liquid temperature and ingredients. Meanwhile, non metal impurities in steel liquid can float to surface and be removed, steel liquid is purified and steel quality is improved. Purging plug bricks are widely used in converter steel making, electric furnace steel smelting and refinery ladles. Air supply bricks have a trend to be used in whole smelting process, including tundish, tornado tank and so on.
As air supply component is important functional refractory material of steel smelting, different materials and structures of air supply bricks can be used for different smelting vessels and operation conditions. There are mainly two kinds of purging plug bricks now: one is converter and electric furnace purging plug, the other is steel ladle purging plug brick. They are significantly different in working condition, using requirements, so the materials, structure and manufacturing crafts of them are different.
Converter bottom blowing gas supply component is important refractory material for top and bottom combined blowing craft, it plays an important role in smelting process. Top and bottom combined blowing converter’s gas supply component is magnesia carbon purging plug, which is installed at converter bottom. Currently, mainly used converter purging plug is isostatic pressing molded magnesia carbon air supply brick. This kind of purging plug brick has small expansion coefficient, good spalling resistance and long service life.
Electric furnace bottom blowing air supply components can be divided into two types. One is direct stirring system air supply bricks, which is similar to converter magnesia carbon containing, high pressure formed, sectionally combined air supply bricks. The other is indirect stirring system air supply components. Purging plug won’t contact with steel liquid directly, and air is supplied by surface air permeable ramming mass. Compared with direct stirring air supply component, indirect stirring air supply component’s service life is longer, and requires large flow rate purging plug bricks.
|Item||Converter air supply component||UHP air supply component||Purging ramming mass|
|Apparent porosity %||4.0||2.93||/|
|Bulk density Mpa||/||56||/|
|Rupture strength Mpa||/||23||/|
|High temperature rupture strength Mpa(1400℃)||10.0||12.6|
|Air flow rate m3.h-1||20||/||/|