Electric arc furnace

01

Know what modern practice achieves

An NPTEL steelmaking lecture (Indian Institute of Technology course) summarises EAF development: power consumption fell from 630 to 290 kWh per tonne, tap-to-tap time from 180 to 40 minutes and electrode consumption "from arounf [sic] 6.2 kg/ton to as low as 1.2 kg/ton" over the period shown, developments strongly supported by secondary steelmaking. [1]

These are trend figures from the lecture's chart, not guarantees for a given furnace and charge. Ask suppliers for reference furnaces with your charge mix and their measured energy, electrode and refractory consumption.

Give the supplier the charge mix (scrap grades, DRI or hot metal share), target tap weight and steel grades, the grid connection and short-circuit power, and the downstream ladle furnace and caster rate.

02

Use chemical energy, foamy slag and injection

The lecture states that "In recent years the chemical energy supply amounts to 35% to 40% of the total energy in most of the modern EAFs"; its sources include oxidation reactions and post-combustion. Foamy slag covers the arc so that more energy goes to the bath rather than the walls; carbon and oxygen are injected to foam the slag when bath carbon is low; the lecture states "Typically carbon injection rates for slag foaming are 2.5 to 5 kg/ ton of steel", and 5–10 kg/t in high-powered furnaces. [3] [4] [5]

Oxygen injection must be controlled to keep iron oxidation, and so yield loss, down; injectors work in five modes (hold, burner, soft lancing for post-combustion, supersonic lancing for decarburisation and foaming, carbon injection). Fixed shell-mounted injectors avoid the splashing and repairs of slag-door lances. [5] [6]

03

Consider scrap preheating and bottom stirring

According to the lecture, scrap preheating with furnace waste heat can cut energy by 40–60 kWh per tonne depending on preheat temperature, electrode consumption by 0.3–0.36 kg per tonne, refractory by 0.9–1.4 kg per tonne and tap-to-tap time by 5–8 minutes; it is economical only when waste heat is used. [4]

Argon or nitrogen bottom stirring, through plugs in contact with the melt or embedded in porous refractory, removes temperature and concentration gradients, shortens tap-to-tap time and reduces refractory, electrode and power consumption. [3]

04

Choose the furnace design features

The lecture describes larger-diameter hearths for bigger charges and lower heat losses; split-shell construction so the upper shell can be changed quickly; high-power and ultra-high-power transformers; eccentric bottom tapping to cut tap time, temperature loss and slag carry-over; and DC arc furnaces as an alternative to AC. [2]

Ask how each feature is matched to your charge, power supply and downstream ladle furnace, and what auxiliary systems (water-cooled panels, off-gas and dust handling, electrode regulation) are included.

05

AC and DC furnaces, top or continuous charging, and auxiliaries

CHNZBTECH and ANCORE between them list AC and DC electric arc furnaces, top-charging and continuous-charging furnaces, and furnace auxiliaries. [7] [8]

CHNZBTECH lists EAFs, top-charging EAFs, submerged arc furnaces and auxiliaries such as water-cooled cables and dust chambers; ANCORE describes turnkey EAF solutions with a team from Xi'an Electric Furnace Research Institute; China Electric (Shanghai) lists its HX series EAF and LF ladle furnaces; Hani lists EAF steelmaking equipment. Capacities and references are suppliers' own claims. [7] [8]

06

Shell, transformer, cooled panels, injection, tapping, stirring and off-gas

Each row links back to the lecture section that describes it; panel cooling has no figure in these sources.

07

Capacity, transformer, electrodes, energy and tap-to-tap for the quotation

Charge mix, tap weight and grid data come from your melt shop. The NPTEL trend figures in the middle column describe the industry, not the furnace being offered.

08

Send the charge, grid and plant data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Charge: [scrap grades and density; DRI or hot metal share; charging method]
Product: [steel grades; tap weight; heats per day; downstream ladle furnace and caster]
Power: [grid voltage; short-circuit power; flicker limits; transformer rating sought]
Chemical energy: [oxygen and carbon injection; burners; post-combustion]
Design: [AC or DC; split shell; eccentric bottom tapping; bottom stirring; scrap preheating]
Utilities: [cooling water; oxygen; natural gas; compressed air]
Environment: [off-gas and dust system; noise]
Documents: [reference plants with consumptions; guarantees and their basis]

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