{"id":2343,"date":"2026-04-29T07:53:47","date_gmt":"2026-04-29T07:53:47","guid":{"rendered":"https:\/\/boshiya.com\/?p=2343"},"modified":"2026-04-29T09:25:57","modified_gmt":"2026-04-29T09:25:57","slug":"electric-arc-furnace-steelmaking-guide","status":"publish","type":"post","link":"https:\/\/boshiya.com\/ja\/blog\/electric-arc-furnace-steelmaking-guide\/","title":{"rendered":"\u96fb\u52d5\u30a2\u30fc\u30af\u7089 (EAF): \u30d7\u30ed\u30bb\u30b9\u3001\u30bf\u30a4\u30d7\u3001\u88fd\u92fc\u30ac\u30a4\u30c9"},"content":{"rendered":"

What Is an Electric Arc Furnace (EAF)? Process, Types, and Steelmaking Applications<\/span><\/p>\n

An electric arc furnace (EAF) is an industrial steelmaking furnace that produces extreme heat through electrical arcs between graphite electrodes and a metallic charge. Unlike blast furnaces that rely on coal and iron ore, an EAF melts pre-reduced feedstock \u2014 primarily scrap steel \u2014 using electricity alone, making them the backbone of the modern recycled steel industry. Electric steelmaking accounts for approximately 30% of global steel production, and EAFs now represent over 49% of all new steelmaking capacity currently under development worldwide.This guide covers the EAF process step by step, compares AC and DC furnace types, reviews graphite electrode specifications, benchmarks EAF against blast furnace-basic oxygen furnace (BF-BOF) steelmaking, and explores the technology’s role in green steel decarbonization. For plant engineers and project teams evaluating steel plant equipment solutions<\/a>, this is the technical reference you need.<\/p>\n

Quick Specs: What Is an Electric Arc Furnace?<\/h2>\n

\"Quick<\/p>\n

An electric arc furnace ignites a metallic charge with a direct face-to-face electrical arc, with line current passing from graphite electrode corners through the charge material. Highly concentrated arcs reach temperatures far beyond any combustion fuel, making the EAF the premier choice for both high-volume scrap recycling and precision alloy making.<\/p>\n

<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n
EAF Quick Specifications Reference<\/caption>\n
Parameter<\/th>\nTypical Range<\/th>\nNotes<\/th>\n<\/tr>\n<\/thead>\n
Furnace capacity<\/strong><\/td>\n1 \u2013 420 t per heat<\/td>\nFoundry units from 1 t; Tokyo Steel (DC) runs 420 t<\/td>\n<\/tr>\n
Arc temperature<\/strong><\/td>\n~3,000 \u00b0C (5,400 \u00b0F)<\/td>\nArc itself; charge reaches 1,600\u20131,800 \u00b0C molten<\/td>\n<\/tr>\n
Transformer power<\/strong><\/td>\n10 \u2013 150+ MVA<\/td>\nMid-sized plant: ~60 MVA; 400\u2013900 V secondary<\/td>\n<\/tr>\n
Heat duration (tap-to-tap)<\/strong><\/td>\n40 \u2013 90 min<\/td>\n~50 min for 80-t AC EAF; ~60\u201370 min for 90-t medium-power<\/td>\n<\/tr>\n
Energy consumption<\/strong><\/td>\n400 \u2013 500 kWh\/tonne<\/td>\nTheoretical minimum: 300 kWh\/t; advanced 280\u2013400 kWh\/t<\/td>\n<\/tr>\n
Electrode type<\/strong><\/td>\nUHP graphite<\/td>\nAC: 3 electrodes; DC: 1 electrode<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

<\/p>\n

Three major structural sections define every EAF: the shell<\/strong> (sidewalls and lower steel bowl), the hearth<\/strong> (refractory-lined lower bowl holding molten metal), and the roof<\/strong> (retractable or swing-out, supporting graphite electrodes through a central delta). Modern plants often raise the furnace off-grade level so ladles and slag pots can be positioned directly beneath either end.<\/p>\n

How Does an Electric Arc Furnace Work? Step-by-Step Process<\/h2>\n

\"How<\/p>\n

Within a single EAF vessel, operators must accomplish tasks that integrated mills spread across multiple units: melt the scrap charge, achieve dephosphorization and decarburization, raise temperature, deoxidize, desulfurize, remove inclusions, and adjust both chemical composition and thermal conditions. That operational density makes EAF process control genuinely demanding. Mastering the EAF steelmaking process from cold charge to tapped heat is the foundation for sound plant investment and engineering decisions.<\/p>\n

Scrap and Metal Feedstock: Preparing the Charge for EAFs<\/h3>\n

<\/p>\n

    \n
  1. Scrap Charging.<\/strong> Scrap steel is loaded into large baskets (“charge buckets”) layered strategically: heavy melt at the base, lighter shred on top for arc protection. With the roof swung open, the basket tips and cold scrap falls in. Charge operators consider this the highest-risk phase \u2014 thousands of kilograms of falling metal displace any retained liquid metal upward. A pre-heater may recover off-gas energy before the basket reaches the melt shop.<\/li>\n
  2. Meltdown (Power-On).<\/strong> Electrodes lower onto the scrap; an arc is struck at reduced voltage to protect the roof. Once arcs bore into the heavy melt layer and are shielded by surrounding scrap, voltage increases and arc length extends \u2014 accelerating melt pool formation. Oxygen lances and sidewall oxy-fuel burners supply chemical heat to cold spots, particularly near the hearth perimeter in AC furnaces. Meltdown accounts for 60\u201370% of total electrical energy consumed per heat. \n
    \u2699 Engineering Note \u2014 Bore-In Voltage Management:<\/strong> After the charge has melted more than three-quarters, the arc is no longer shielded by solid scrap. Prolonged high-power input at this stage directly exposes the furnace roof and sidewalls to arc radiation. Operators reduce power at this transition point, but without real-time melt pool sensors, the timing relies heavily on operator experience \u2014 listening to furnace acoustics or watching light emissions from the slag door.<\/div>\n<\/li>\n
  3. Refining. Once the entire charge of scrap is in liquid form, additional slag\u2014specifically calcined lime and dolomite mortar\u2014are introduced to produce a basic slag layer. Injection of oxygen dephosphoryates and removes phosphorus, sulphur, silicon, aluminum, manganese, as well as additional carbon. Simultaneous injection of carbon into the slag releases CO gases which “foam” the slag, improving arc shielding, thermal efficiency, and electrical efficiency metrics. Should the temperature fall below roughly 1,530 C, the C\u2013O combination begins to temporarily slow or stop, then reverse (“surge back”); this process produces violent slag overflow. Real-time sampling of temperature and chemistry occur using automated Lances; a “chill sample” is spectrometrically examined to verify grade.<\/li>\n
  4. Tapping.<\/strong> Once temperature and chemistry targets are met, the furnace tilts and liquid steel flows through an eccentric bottom tap-hole (EBT) into a pre-heated ladle. Alloy additions are made during tapping. A “hot heel” \u2014 a few tonnes of retained liquid steel and slag \u2014 is often left to preheat the next charge and accelerate its meltdown. From there, the ladle moves to a ladle furnace (LF)<\/strong> for secondary steelmaking \u2014 final chemistry and temperature adjustment \u2014 before continuous casting. Each heat of steel from charge to tap runs 60\u201390 minutes in a modern EAF.<\/li>\n<\/ol>\n

    <\/p>\n

    \u26a1 Common Misconception:<\/strong> Many engineers assume EAF operations are as inflexible as blast furnaces, which run continuously for years at a time and cannot simply be “paused.” In reality, an EAF can be cold-started in under an hour and shut down just as quickly \u2014 a major operational advantage for plants adjusting to demand fluctuations or electricity pricing windows.<\/div>\n

    AC vs. DC Electric Arc Furnace \u2014 Types and Configurations<\/h2>\n

    \"AC<\/p>\n

    Two primary EAF configurations dominate modern steelmaking. A DC arc furnace uses a single graphite electrode and a conductive hearth return path; an AC design uses three electrodes fed by a three-phase supply. Understanding their differences allows project teams to select the right design for their production scale, power supply constraints, and scrap mix. For detailed steel plant configuration guidance<\/a>, compare the key parameters below.<\/p>\n

    <\/p>\n

    \n\n\n\n\n\n\n\n\n\n\n\n
    AC EAF vs. DC EAF \u2014 Technical Comparison<\/caption>\n
    Parameter<\/th>\nAC (Three-Phase)<\/th>\nDC (Single Electrode)<\/th>\n<\/tr>\n<\/thead>\n
    Electrodes<\/strong><\/td>\n3 graphite electrodes (three-phase supply)<\/td>\n1 graphite electrode + conductive hearth return<\/td>\n<\/tr>\n
    Capacity range<\/strong><\/td>\nFoundry units to 300+ t<\/td>\n30 t to 420 t (Tokyo Steel)<\/td>\n<\/tr>\n
    Electrode consumption<\/strong><\/td>\nHigher (3 electrodes in simultaneous use)<\/td>\nLower per tonne (single electrode; less thermal cycling)<\/td>\n<\/tr>\n
    Power quality<\/strong><\/td>\nHigher harmonic distortion; visible flicker on grid<\/td>\nLower harmonics; less grid flicker<\/td>\n<\/tr>\n
    Hearth uniformity<\/strong><\/td>\nHot\/cold spots between electrodes; burners compensate<\/td>\nMore uniform melt bath stirring<\/td>\n<\/tr>\n
    Key limitation<\/strong><\/td>\nMore electrode breakage risk; hot spot refractory wear<\/td>\nConductive hearth maintenance is a long-run bottleneck<\/td>\n<\/tr>\n
    Best suited for<\/strong><\/td>\nMost mini-mills; any grid infrastructure<\/td>\nHigh-capacity, low-electrode-cost operations<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

    <\/p>\n

    <\/p>\n

    \n

    \ud83d\udd27 AC vs. DC Selection Framework:<\/strong><\/p>\n