Electric arc furnace (EAF) - scrap-based steelmaking with electric heating

An electric arc furnace (EAF) melts steel scrap, direct reduced iron and alloy additions in a refractory-lined vessel using high-current arcs from graphite electrodes. It is the core furnace of mini-mill steelmaking and an important route for lower-carbon steel when supplied by low-carbon electricity and high-quality scrap or DRI.

Process and gas path

A typical EAF cycle includes charging, melting, oxygen lancing, carbon injection, slag foaming, refining, tapping and turnaround. Off-gas leaves through a fourth-hole duct in the roof and is usually combined with secondary fume captured by canopy hoods or doghouse enclosures. The gases pass through water-cooled ductwork, spark boxes or settling chambers, dilution air systems and then a large baghouse.

Dust and fume character

EAF dust is fine, reactive and metal-rich. It commonly contains iron oxides, zinc oxide from galvanised scrap, lime, carbon, alkalis, chlorides and trace metals. Zinc-bearing dust can be sticky or hygroscopic, especially when temperature and humidity vary. Dust loading changes sharply during charging, oxygen blow and tapping, so the extraction system must handle both steady flow and high-intensity fume bursts.

Failure modes and maintenance

Common reliability issues include duct accretion, spark carryover, baghouse hopper bridging, high differential pressure, bag abrasion, fan imbalance, damper sticking and fugitive emissions during furnace movements. Refractory wear, electrode breakage and water leaks are separate furnace risks, but they can also change dust chemistry and off-gas temperature.

Maintenance teams watch baghouse pressure drop, compartment temperature, broken-bag detectors, hopper level, rotary valves, screw conveyors and fan vibration. Dust handling is safety-critical because EAF dust can contain regulated metals and may need controlled disposal or recycling.

Acoustic cleaning relevance

Sonic horns are useful on EAF baghouse hoppers, dirty-air plenums and selected duct transitions where fine dust bridges or clings between pulse-cleaning events. They do not replace pulse-jet cleaning of bags, but they help keep dust moving out of compartments and reduce manual intervention around hazardous dust.

Design and safety notes

EAF fume systems must tolerate sparks, pressure pulses, air dilution and high dust swings. Spark boxes, dropout chambers and duct velocities are selected to protect bags from fire while avoiding duct settlement. Water-cooled ducts need leak detection because water contacting hot metal or dust can create violent events. Dust handling is also a compliance issue: EAF dust is often recycled for zinc recovery or managed as hazardous waste depending on jurisdiction and composition. Cleaning devices must be maintainable without exposing workers to uncontrolled dust release.

Plant interfaces and control variables

An electric arc furnace is not only a melting vessel; it is the centre of a high-energy material-handling and gas-cleaning system. The furnace interacts with scrap charging, direct-reduced iron feed, oxygen lances, carbon injection, slag foaming, roof extraction, off-gas ducts, water-cooled panels, transformers, electrode regulation and baghouse capacity. Key variables include arc power, tap-to-tap time, oxygen flow, carbon addition, slag basicity, furnace pressure, off-gas temperature and post-combustion in the duct.

Failure modes include water leaks into the shell or roof, electrode breakage, refractory washout, slag foaming instability, uncontrolled fume release during charging, duct accretion and baghouse overload after a hot or dusty heat. Acoustic cleaning is usually more relevant downstream than at the furnace itself. It can help keep dry duct sections, dropout boxes or hoppers clear, but it must be placed outside zones where impact, high radiant heat or molten material exposure would destroy equipment.

Electric arc furnace