Evaluation of recycled MgO-C bricks and dead-burned dolomite fines in setting slag foaming in the electric arc furnace

Abstract

Production cost reduction for the Electric Arc Furnace (EAF) technology is strongly dependent on the efficiency of the electrical energy being introduced into the metal bath. Besides EAF technology, the slag foaming process is currently applied to some other equipment for steel production aiming to save energy, productivity improvements, enhance the refractory service life and inhibit steel re-oxidation. In this way, this study involved the recycling options of Crushed MgO-C spent refractories removed from the EAF without complex and costly beneficiation, with emphasis on its application as a slag conditioner, since its composition presents high MgO content. The experiments were performed in a laboratory induction furnace and the temperature was controlled at 1700°C.The initial height of the slag was recorded and foaming briquettes added into the furnace. The experiments were carried out for 30 minutes. When the foaming process was finalized, an aliquot from the slag was collected to be analyzed by chemical analysis. Then, the metal with slag was tapped into a mold. The results indicated that the best viscosity was 0.39poise. The maximum height of foam formation was observed for a binary basicity greater than 1.2. The concentration of MgO in the slag is close to the saturation point.

Visualization of Slag Data for Efficient Monitoring and Improvement of Steelmaking Slag Operation in Electric Arc Furnaces, with a Focus on MgO Saturation

“…The amount of dissolved MgO in the slag from the beginning of heating until tapping is related to the MgO losses from the lining, due to the MgO mass balance [19]. Therefore, it is recommended to apply MgO-containing slag additives or modifiers as early as possible in order to decrease the corrosion potential of the process slag [4,5,[19][20][21][22]. This keeps the MgO activity in the slag at high levels, ideally close to 1.…”