Basic oxygen

The most basic oxygen transfer equation (6) states that the amount of diffusion is proportional to the surface of the interface (6,20) ... 

Most ferrous scrap is recycled in steelmaking processes by melting the scrap in either a basic oxygen or an electric arc furnace. However, a significant market exists for cast-iron products, which are also made by melting ferrous scrap. In 1991, world production of cast irons was estimated at nearly 3.9 X 10 t at over 14,000 iron foundries (15). 

In Germany and Japan, pulverized quicklime is used in making self-fluxing sinters, partially replacing limestone. Granular dead-burned dolomite is stiU used to protect the refractory lining of open-hearth and electric furnaces, but not the basic oxygen furnace. Refractory time has declined with the... 

A comprehensive history of ferrous scrap recycling ia the United States beginning ia 1646 has beea pubUshed (3). Some selected eveats of iaterest iaclude the first opea-hearth steel produced (1868) the first commercial direct-arc electric furnace steel produced ia the United States (1906) the first large iaduction furnace iastaHed ia the United States (1914) the first basic oxygen steel produced ia the United States (1954) the rise of continuous casters and scrap-based minimills (1965) the first thin-slab continuous caster at a minimill (1989) U.S. exports and imports of ferrous scrap at record highs (1990) and the end of production of open-hearth steel (1991). 

Pig iron and iron and steel scrap are the sources of iron for steelmaking in basic-oxygen furnaces. Electric furnaces have rehed on iron and steel scrap, although newer iron sources such as direct-reduced iron (DRI), iron carbide, and even pig iron are becoming both desirable and available (see Iron bydirectreduction). In basic-oxygen furnaces, the pig iron is used in the molten state as obtained from the blast furnace in this form, pig iron is referred to as hot metal. 

In oxygen steelmaking, 99.5% pure oxygen gas is mixed with hot metal, causiag the oxidation of the excess carbon and siHcon ia the hot metal and thereby produciag steel. In the United States, this process is called the basic-oxygen process (BOP) (4,9,10). The first U.S. commercial iastallation began operation in 1955. 

Top-Blown Basic Oxygen Process. The top-blown basic oxygen process is conducted ia a cylindrical furnace somewhat similar to a Bessemer converter. This furnace has a dished bottom without holes and a tmncated cone-shaped top section ia which the mouth of the vessel is located. The furnace shell is made of steel plates ca 50-mm thick it is lined with refractory 600—1200-mm thick (11). 

Fig. 4. Sketch of a basic-oxygen steelmaking furnace, where an oxygen lance is iaserted through the mouth of the furnace (1).

Because the basic-oxygen process uses a refining agent containing practically no nitrogen, the product has a low nitrogen content. Oxygen residues depend on the carbon content. 

Residual alloying elements such as copper, nickel, or tin are usually considered undesirable. Their main source is purchased scrap. Because of the generally high consumption of hot metal in the basic-oxygen process, the residual alloy content is usually sufficiently low, depending on the quaUty of the purchased scrap. 

The finished steel from any furnace, whether basic-oxygen or electric, is tapped into ladles. Most ladles hold all the steel produced in one furnace heat. 

In modem steel (qv) manufacture, pebble quicklime is used as a flux in the basic oxygen, basic open-hearth, basic Bessemer, and basic electric furnaces. 

Crambe was introduced to the United States in the 1970s. It is an oilseed, the oil of which is very high in emcic acid [112-86-7] (13-docosanoic acid), C22H42O2. This oil can be used to provide industrial lubricants, especially those needed for the basic oxygen furnace process for making steel (qv). Crambe is grown in relatively small volume in the midwestem United States. 

Secondary Brass and Bronze Production Plants Primary Emissions from Basic Oxygen Process Furnaces for Which Construction Commenced after June 11, 1973... 

Secondary Emissions from Basic Oxygen Process Steelmaking Facilities for Which Construction Commenced after January 20, 1983 Sewage Treatment Plants Primary Copper Smelters Primary Zinc Smelters... 

Basic oxygen furnaces oxygen blowing Fumes, smoke, CO, particulates (dust) Proper hooding (capturing of emissions and dilute CO), scrubbers, or electrostatic precipitator... 

At low temperatures unstable adsorption products or reaction intermediates could be trapped. Thus, carbonite CO, ions arise on CO interaction with basic oxygen ions which account for catalytic reaction of isotopic scrambling of CO or thiophene on activated CaO. 

Bessemer Open hearth Electric Basic oxygen furnace Total... 

Basic oxygen furnaces (BOFs) have largely replaced open hearth furnaces for steelmaking. A water-cooled oxygen lance is used to blow high-purity oxygen into the molten metal bath. This causes violent agitation and rapid oxidation of the carbon, impurities, and some of the iron. The reaction is exothermic, and an entire heat cycle requires only 30-50 min. The atmospheric emissions from the BOF process are listed in Table 30-16. 

Air Pollution Emissions and Controls Basic Oxygen Furnace... 

BPM 20 Iron works and steel works. Basic oxygen steel plants... 

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