1.55 X 106 Btu per ton of sinter
Largest source: windbox
Particulate: iron and sulfur oxides, carbonaceous compounds, aliphatic hydrocarbons, chlorides
Largest source: wet air pollution control devices Typical wastewater volume: 120gal/t of sinter
Source: From Energetics, Inc., Energy and Environmental Profile of the U.S. Iron and Steel Industry, DOE/EE-0229, U.S. Department of Energy, Washington, DC, 2000.
emissions are mainly iron and calcium oxides. A wide variety of organic and heavy metal hazardous air pollutants (HAPs) may be released during sinter operations from the coal/coke on the sinter grate and iron, respectively. The heavy metal HAPs include cadmium, chromium, lead, manganese, and nickel. Total HAPs releases from individual sinter manufacturing operations may exceed 10 t/yr.6 The typical components of the dust generated during sintering practice include iron, carbon, sulfur, Fe2O3, SiO2, Al2O3, CaO, and MgO.
Large quantities of carbon monoxide and sulfur dioxide are also emitted during iron making. The primary source of blast furnace particulate emissions is due to the contact of molten iron and slag with the air above their surface during casting (removal of the molten iron and slag from the furnace). Emissions are also generated by drilling and plugging the taphole, which is an opening at the base of the furnace to allow iron and slag to flow out into runners that lead to transport ladles. Heavy emissions result from the use of an oxygen lance to open a clogged taphole. Another potential source of emissions is the blast furnace top. No serious emission problem is created if charging is through a sealed system. However, minor emissions may occur during charging from imperfect bell seals in the double bell system. Occasionally, a cavity may form in the blast furnace charge, causing a collapse of part of the charge above it. The resulting pressure surge in the furnace opens a relief valve to the atmosphere to prevent damage to the furnace by the high pressure created and is referred to as a "slip."14
During hot metal desulfurization, used to remove or alter sulfur compounds in the hot metal, the exhaust gases are found to bear particulate matter. Emissions may also result from slag handling. Sulfur dioxide is formed when the sulfur in the slag is exposed to air. The presence of moisture can
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