Sponge-reduced iron

Collective (2003) The Iron Ore Market 2002-2004. UNCTAD Iron Ore Trust Fund, UNCTAD, Geneva, Switzerland. 

Harvey, Ph. (1982) Engineering Properties of Steels. ASM Books, Materials Park, OH. 

Hanson, A. Lula, R.A. (1985) Stainless Steels. ASM Books, Materials Park, OH. Roberts, G.A. Cary, R.A. (1980) Tool Steels, 4th. ed. ASM Books, Materials Park, OH. 

(2004) Stahlschlussel (Key to Steel), 20th ed. ASM Books, Materials Park, OH. BRINGAS, J.E. (1995) The Metals Black Book, Vol. I Ferrous Metals, 2nd ed. CASTI, Edmonton, Canada. 

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Direct reduced iron (DRI, sponge iron), metal powders, titanium sponge Processing of metal or metal-bearing wastes for recycling... 

Iron oxide also can be reduced in a direct reduction furnace, which operates at much lower temperatures (1300-2000°F) than a blast furnace and produces a solid "sponge iron" rather than molten Iron. Because of the milder reaction conditions, the direct reduction furnace requires a higher grade of iron ore (with fewer impurities) than that used in a blast furnace. The iron from the direct reduction furnace is called DRI (directly reduced iron) and contains —95% iron, with the balance mainly silica and alumina. 

The coke must be strong enough to resist the weight of overburden in the blast furnace, which is why coking coal is so important in making steel by the conventional route. However, the alternative route to is direct reduced iron, where any carbonaceous fuel can be used to make sponge or pelletized iron. 

The furnace was fed from above with iron ore, limestone and charcoal. Air was blown into the lower parts of the furnace. Then carbon monoxide CO was formed, which reduced iron oxide to solid iron sponge in the middle of the furnace. In the lower part the iron absorbed carbon and melted as pig iron with 4% carbon. 

Sponge powdered iron contains many small holes in the iron particles due to the escaping of the oxygen when the iron is reduced. Water atomized powdered iron has much smoother and denser particles as the powder is formed from molten iron. 

In atomization, a stream of molten metal is stmck with air or water jets. The particles formed are collected, sieved, and aimealed. This is the most common commercial method in use for all powders. Reduction of iron oxides or other compounds in soHd or gaseous media gives sponge iron or hydrogen-reduced mill scale. Decomposition of Hquid or gaseous metal carbonyls (qv) (iron or nickel) yields a fine powder (see Nickel and nickel alloys). Electrolytic deposition from molten salts or solutions either gives powder direcdy, or an adherent mass that has to be mechanically comminuted. 

Chenot An early steelmaking process. Iron ore was first reduced to sponge iron this was mixed with charcoal, manganese, and resin and compressed into small blocks. These blocks were then melted as in the Crucible process. Invented by A. Chenot in France in 1846 and operated on a small scale in Sheffield in the 1860s, but abandoned after the introduction of the Open Hearth process. 

Kinglor-Metor A DR process. Lump iron ore, mixed with coke or coal, and lime, is passed through a heated rectangular chamber and there reduced to sponge iron. First operated in Italy in 1973 and now operating in Burma. See DR. 

One of the more important alternatives to the blast furnace for the production of iron is direct reduction of pelletised ore in a shaft reactor. The reducing gas mixture is usually obtained by steam reforming of natural gas and flows upward,countercurrent to the downward flow of solids. Sponge iron obtained by direct reduction may be used directly in arc furnaces for steel production. 

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