Why mag-c bricks is mostly prefer for ladle and EAF, why not spinel refractory?

EAF is all mag-carbon. Why it works well and zoning is done based on carbon level, anti-oxidant, graphite quality and magnesia grain quality. In steel ladles, however, mag-carbon is the solution in the slagline only. If the shop is in an alumina killed process, the common is alumina/magnesia carbon for the barrel and bottom. For silicon killed shops, the norm is dolomite (carbon bond normally) or magnesia carbon. The selection comes down to what works in the application and which technology is most cost effective. The later takes on a regional aspect. In fact one shop in ---- (blastfurnace not EAF) is using a bottom and barrel that is alumina magnesia castable with a mag-carbon slagline, why? Simple they maintain the barrel profile with shotcrete and recasting through many slaglines. In fact they only reline the barrel and bottom from the shell once a year!


MgO-C is more compatible with high lime fluid slag. Spinel is more neutral and performs well in molten metal contact.

In basic steel making process, the slag is high in lime. So the brick need to be compatible with the slag. So MgO.C is one of the brick suitable for ladle metal line & only brick suitable for slag line. Graphite addition provides nonwetting character, spalling resistance and additional corrosion resistance especially against FeO. Other bricks Al2O3-MgO-C (Al killed) & Dolo-C (Si-Killed) bricks are used mostly on metal line of ladle. Some ultra low-C, Al-killed steel customers use Al2O3-MgO castable & Spinel bricks in ladle metal line, prefab/precast ladle bottom depending on their plant practices. In EAF also basic slag & hot spots suits MgO.C bricks. It is also economic against spinel brick.