What is the usual Current and Voltage of an Electric arc furnace?
U: 120-1000V
I: 60-80 kA
What is the plasma temperature?
5000-15000K
What role do the busbars and flexible cords play in EAF?
They distribute electrical power to the electrodes, with flexibility to allow movement of electrodes.
What is the typical material of electrodes used in EAF?
Graphite electrodes, with varying sizes depending on furnace capacity.
How does electrode regulation impact the EAF process?
Regulating electrode distance controls the arc length and intensity, affecting heat generation and melting efficiency.
What is the role of the roof in EAF?
It contains the heat within the furnace and has openings for electrode entry and exhaust gas exit.
What is the tap-to-tap time in EAF operations?
It varies from 45 minutes to 2 hours, including charging, melting, refining, and tapping.
Where isoxygen blowing conducted in EAF?
one or multiple of the following:
sidewall insertion (working door)
oxifuel lances (switch to oxygen only)
specific fixed O2 lances on the sidewall
bottom injection through tuyere
What is the purpose of using oxy-fuel burners in EAF and how are they powered?
To provide additional heat for melting scrap, especially in cold spots, and assisting in initial heating.
How does scrap type affect the EAF process?
Different scrap types (heavy, light, shredded) have varying melting characteristics and impact furnace efficiency.
What is the significance of chemical energy in EAF?
It supplements electrical energy, reducing overall power consumption and improving process efficiency.
Explain the concept of foaming slag in EAF.
How: Pulverized C is injected into mold and reacts with O2 to form CO bubbles
Why: Better heat transfer to bath, noise reduction, lower gas absorbtion.
How is post-combustion managed in EAF?
By oxidizing CO to CO2, it improves energy efficiency and reduces emissions.
What are the main considerations in the mass and heat balance of EAF?
Accounting for input and output energies, including electric, chemical, and thermal aspects to optimize the process.
How is oxidation of organic matter in scrap managed in EAF?
Organic components are oxidized to CO2 and H2O, affecting emissions and requiring efficient evacuation systems.
What are the main types of electrode wear in EAF?
Tip consumption (sublimation), sidewall oxidation, and mechanical stresses leading to breakage.
How is water cooling utilized in EAF?
In cooling panels and electrode systems to manage furnace temperature and prolong refractory life.
How long do refractories last in a conventional EAF?
They last for 90 to 130 heats.
What is the lifespan of refractories in a watercooled EAF?
Up to 5000 heats
What is the role of DRI in EAF steelmaking?
DRI is used for its low impurities and dilution effect, typically comprising 10-20% of the charge.
What is the typical charge size for an EAF?
50-150t
What types of scrap are used in EAF steelmaking?
Internal scrap, process scrap, and capital scrap.
What are the stages of melting operations in an EAF?
Charging, melting, refining and heating, and tapping.
How is scrap arranged in the EAF for efficient melting?
Fine and light scrap is placed on top and the bottom, with coarse and heavy scrap in the center. Flux additions are placed on the side.
How is refractory wear measured in an EAF?
Using the Refractory Wear Index (RWI) formula.
Describe the stages for the arc length of the EAF process.
What influences the stability of the foamed slag?
Slag viscosity
Surface tension
Flow rate of O2 blowing
How should the slag viscocity be in an EAF?
low to favour the slag metal reaction
not too low to avoid damaging the walls
How does the typical energy balance look like in an EAF?
What is the main reason for losses in an EAF?
Due to the cooled sidewalls.
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