In electric arc furnace (EAF) steelmaking, the quality and performance of the bottom ramming mass are critical to ensuring furnace integrity, extending service life, and optimizing steel production efficiency. So, what are the essential technical features of an ideal EAF bottom ramming mass?
- Rapid sintering to form a dense working layer
- Phase transition from low or mediumto high-melting compounds
- Resist slag penetration while maintaining slight porosity in deeper layers
How Does EAF Bottom Ramming Mass Work and Wear Over Time?
The sintering process of dry ramming mass starts after the furnace is powered on. When the temperature reaches around 1250°C, minor Fe₂O₃ components help lower the melting point of CaO, producing a small amount of liquid phase that dissolves into periclase (MgO). Conversely, some MgO also dissolves into calcium ferrite, forming limited solid solutions, which facilitate the initial sintering stage.
As the scrap melts and the temperature rises, these phases evolve. The liquid CaO-rich phases may precipitate as CaO crystals, transform into calcium silicate (C₂S), or enrich into high-calcium zones. Eventually, the raw components transition from MgO + C₂F to RO + SiO₂ structures, completing the sintering process.
Moreover, the interaction between periclase and water vapor can generate magnesium hydroxide gas:
MgO(s) + H₂O(g) → Mg(OH)₂(g)
2MgO(s) + H₂O(g) → 2Mg(OH)(g) + ½O₂(g)
This highlights the importance of moisture prevention, especially during construction and furnace preheating. Water leaks or humidity can significantly hinder the sintering process and cause cracking.
Proper sintering ensures a stable furnace bottom, which also helps absorb the impact of charging operations. However, if temperatures become too high, excessive migration of liquid phases toward molten steel can lead to surface cracking. Thus, maintaining optimal temperature control during preheating is essential to preserve the integrity of the sintered layer and meet the metallurgical requirements of the steelmaking process.
Wear Mechanism and Performance Benefits
The corrosion of the EAF bottom ramming layer is a slow, cyclical reaction governed by time and temperature. With each steelmaking heat, the working surface undergoes a thin oxidation reaction, typically within 1 mm depth, and is regenerated in the following cycle. This dynamic regeneration makes ramming-mass-lined furnace bottoms more chemically stable and longer-lasting than traditional brick linings.
Importantly, the compaction level during installation plays a decisive role. Poorly compacted ramming mass may lead to localized melting, block detachment, or even cold steel penetration. Therefore, meticulous ramming during construction is essential for maximizing service performance and furnace longevity.
