Electric arc furnaces (EAF) are implementing oxy-fuel burners, injection of oxygen and natural gas through tuyeres, and more energy recovery through post-combustion in an effort to increase productivity. The result has been increased roof temperatures and the creation of localized areas of stress. These changes demand that the refractories utilized in the EAF Delta section be more resistant to thermal shock, thermal cycling, chemical corrosion, and mechanical erosion. A summary of factors affecting the delta life should include;
- Refractory quality
- Scrap quality/chemistry
- Slag practice and chemistry
- Furnace power input
- Oxygen injection practice and volume input
- Operating temperature
- Charging quantity and practice
- Fume evacuation system and practice
- Electrode cooling
- Furnace maintenance cycle.
MMI’s Refractory Technology for the EAF Delta is based on our line of Metpump® no-cement castables (pumpables). These materials contain no calcium aluminate cement and instead rely on a unique colloidal silica (sol-gel) binder system. Our delta line of materials range from 70% – 90% Al2O3 and all exhibit excellent hot modulus of rupture, creep resistance, alkali and acid resistance, thermal shock resistance and thermal cycling resistance when compared to cement bearing castables.
Steel Ladles are being operated for longer continuous periods while minimizing downtime for maintenance or repair. In addition, an ever-increasing number of metallurgical operations are now being performed in the ladle as opposed to the furnace. These changes demand that the refractories used should last longer, be easy to install, lend themselves for use in a preventative maintenance program, while maintaining compatibility with the steelmaking operational and/or metallurgical requirements. MMI has developed a family of materials, which are achieving a performance level in steel ladles considered to be the new standard.
Benefits – Some of these designs, which range from castable bottoms only to cast safety linings and working linings, are exhibited on the following pages. This range of design reflects Magneco/Metrel’s desire to develop the system best suited for each and every steel plant.
- Increased ladle availability
- Reduction of total ladles due to increased ladle availability
- Longer service life of refractory
- Increased safety lining and steel shell life
- Increased safety due to elimination of joints
- Reduction of heat loss
- Increased ladle volume
- Reduction of total cost per ton of steel