Sources of iron

After aluminium, iron is the most abundant metal and the fourth most abundant of all the elements it occurs chiefly as oxides (for example haematite (FCjO,), magnetite (lodestonej (FC3O4) and as iron pyrites FeSj- Free iron is found in meteorites, and it is probable that primitive man used this source of iron for tools and weapons. The extraction of iron began several thousand years ago, and it is still the most important metal in everyday life because of its abundance and cheapness, and its ability to be cast, drawn and forged for a variety of uses. 

Even high-quality ammonium acetate contains a significant amount of iron. Why is this source of iron not a problem ... 

Since all samples and standards are prepared using the same volume of ammonium acetate buffer, the contribution of this source of iron is accounted for by the calibration curve s reagent blank. 

Minerals. Iron-bearing minerals are numerous and are present in most soils and rocks. However only a few minerals are important sources of iron and thus called ores. Table 2 shows the principle iron-bearing minerals. Hematite is the most plentiful iron mineral mined, followed by magnetite, goethite, siderite, ilmenite, and pyrite. Siderite is unimportant in the United States, but is an important source of iron in Europe. Tlmenite is normally mined for titania with iron as a by-product. Pyrite is roasted to recover sulfur in the form of sulfur dioxide, leaving iron oxide as a by-product. 

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. 

Methods exist to make impure iron direcdy from ore, ie, to make DRI without first reducing the ore in the blast furnace to make pig iron which has to be purified in a second step. These processes, generally referred to as direct-reduction processes, are employed where natural gas is readily available for the reduction (see also Ironbydirectreduction). Carbonization of iron ore to make iron carbide as an alternative source of iron units is in its infancy as of the mid-1990s but may grow. 

The activation of aromatics by organo-iron groups has been used with two families of complexes [10-13], both synthesized from the arene and A1C13 with variation in the source of iron only [19-20] as shown in Scheme II ... 

Precipitated iron also acts as a binder and forms deposits with other materials. The source of iron originates either from contaminated condensate or from MU water, where it is present in the form of ferrous bicarbonate [Fe(HC03)2]. 

Iron oxides are complex corrosion deposits of variable composition that originate from anywhere in the boiler plant system and then are transported to some other location (usually back to the boiler). The most common sources of iron oxide are the economizer (pre-boiler section), boiler tubes (boiler section) and the condensate system (post-boiler section). 

With the same tactic, a meta-stable 3-coordinate iron(III) imido complex was reported by Holland and coworkers [40]. Using the diketiminate-supported dinitrogen iron(I) complex [L T eNNFeU ] as a source of iron(I) precursor [L = 2,4-bis (2,6-diisopropylphenylimino)pent-3-yl], the addition of adamantyl azide (AdN3) in... 

R. Pinton, S. Cesco, M. De Nobili, S. Santi, and Z. Varanini, Water- and pyrophosphate-extractable humic substances fractions as a source of iron for Fe-dettcient cucumber plants. Biol. Fert. Soils 26 23 (1998). 

TABLE 63-2. Food Sources of Iron, Folic Acid, or Vitamin B125... 

Spent foundry sand can be used as a good source of silica in manufacturing portland cement. Also, the clay fraction of foundry sand is an additional source of iron and aluminum oxides. According to the portland cement industry, spent foundry sand can be beneficially used in the manufacture of Portland cement, as sand possesses the following characteristics ... 

Another potential source of iron, at least for hepatocytes, is receptor-independent uptake of iron from transferrin. This appears to involve an iron uptake pathway from transferrin which is neither suppressed in hepatocytes by antibodies to TfR (Trinder et at, 1988), nor by transfection of HuH-7 hepatoma cells with transferrin receptor anti-sense cDNA (Trinder etat, 1996). The same pathway may also be utilized for iron uptake from isolated transferrin N-lobe, which is not recognized by the receptor (Thorstensen et at, 1995). The possible role of TfR2 in this process remains to be established, as does the physiological importance of this pathway in intact liver. Human melanoma cells (Richardson and Baker, 1994) and Chinese hamster cells lacking transferrin receptors but transfected with melanotransferrin (Kennard et at, 1995) use another pathway for transferrin iron uptake, independent of the transferrin receptor, but utilizing iron transfer from transferrin or simple iron chelates to membrane-anchored melanotransferrin, and from there onwards into the cellular interior. 

Lynch et al. (5 7) found non-heme iron absorptions, as measured by single test meals, for black beans, lentils, mung beans split peas, and whole soybeans to be low (0.84 to 1.91%). This suggests that many commonly consumed legumes are poor sources of iron whether legumes other than soy may have an "offsetting" enhancing effect on heme-iron absorption cannot be predicted. 

Raiswell R, Canfield DE (1998) Sources of iron for pyrite formation in marine sediments. Am J Sci 298 219-245... 

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