Scrap metal Direct reduced iron Hot briquetted iron Cold pig iron Hot metal
Alloy materials (e.g., aluminum, manganese, chromium, nickel) Fluxes (e.g., lime) Electricity Oxygen Nitrogen Natural gas Oil
Coal or other carbon source Water
Molten steel Slag
Nitrogen oxides and ozone
EAF emission control dust and sludge (K061)
Source: From U.S. EPA, Profile of the Iron and Steel Industry, EPA 310-R-95-005, U.S. EPA, Washington, DC, 1995.
as oil, grease, and other combustible materials evolve from the surface of the scrap. In the presence of sufficient oxygen these compounds will burn to emit more of CO2. NOX is formed in furnace operations when nitrogen passes through the arc between electrodes and also during burner use in EAFs. Levels of about 36 to 90 g of NOX per ton of steel have been reported.1
The organic compounds present in scrap mixes are burned off as VOCs in the furnace or destroyed by preheating followed by afterburning. However, in the absence of sufficient oxygen these hydrocarbon compounds enter the off-gas system. Iron and zinc oxide are the predominant particulate constituents emitted during melting, and nitrogen oxides and ozone are generated in minor amounts. During the refining process small amounts of calcium oxide may also be emitted from the slag. Melting emissions account for about 90% of total EAF emissions. The remaining 10% of emissions are generated during charging and tapping. Iron oxides and oxides from the fluxes are the primary constituents of the slag handling emissions. During tapping, iron oxide is the major particulate compound emitted.14
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