iron

1. (Symbol Fe) A silvery-white, lustrous, malleable, ductile, magnetic or magnetizable, metallic element occurring abundantly in combined forms, notably in hematite, limonite, magnetite, and taconite, and used alloyed in a wide range of important structural materials. Atomic number 26; atomic weight 55.845; melting point 1,535°C; boiling point 2,750°C; specific gravity 7.874 (at 20°C); valence 2, 3, 4, 6.
2. An implement made of iron alloy or similar metal, especially a bar heated for use in branding, curling hair, or cauterizing.
3. Great hardness or strength; firmness: a will of iron.
4. Sports. Any of a series of golf clubs having a bladelike metal head and numbered from one to nine in order of increasing loft.
5. A metal appliance with a handle and a weighted flat bottom, used when heated to press wrinkles from fabric.
6. A harpoon.
7. irons Fetters; shackles.
8. A tonic, pill, or other medication containing iron and taken as a dietary supplement.

1. Made of or containing iron: iron bars; an iron alloy.
2. Strong, healthy, and capable of great endurance: an iron constitution.
3. Inflexible; unyielding: iron resolve.
4. Holding tightly; very firm: has an iron grip.

1. 1. To press and smooth with a heated iron: iron clothes.
   2. To remove (creases) by pressing.
2. To put into irons; fetter.
3. To fit or clad with iron.

To iron clothes.

iron out

1. To settle through discussion or compromise; work out.

in irons Nautical.

1. Lying head to the wind and unable to turn either way.

1. An undertaking or project in progress: has many irons in the fire this year.

[Middle English iren, from Old English īren.]

Background

Iron is one of the most common elements on earth. Nearly every construction of man contains at least a little iron. It is also one of the oldest metals and was first fashioned into useful and ornamental objects at least 3,500 years ago.

Pure iron is a soft, grayish-white metal. Although iron is a common element, pure iron is almost never found in nature. The only pure iron known to exist naturally comes from fallen meteorites. Most iron is found in minerals formed by the combination of iron with other elements. Iron oxides are the most common. Those minerals near the surface of the earth that have the highest iron content are known as iron ores and are mined commercially.

Iron ore is converted into various types of iron through several processes. The most common process is the use of a blast furnace to produce pig iron which is about 92-94% iron and 3-5% carbon with smaller amounts of other elements. Pig iron has only limited uses, and most of this iron goes on to a steel mill where it is converted into various steel alloys by further reducing the carbon content and adding other elements such as manganese and nickel to give the steel specific properties.

History

Historians believe that the Egyptians were the first people to work with small amounts of iron, some five or six thousand years ago. The metal they used was apparently extracted from meteorites. Evidence of what is believed to be the first example of iron mining and smelting points to the ancient Hittite culture in what is now Turkey. Because iron was a far superior material for the manufacture of weapons and tools than any other known metal, its production was a closely guarded secret. However, the basic technique was simple, and the use of iron gradually spread. As useful as it was compared to other materials, iron had disadvantages. The quality of the tools made from it was highly variable, depending on the region from which the iron ore was taken and the method used to extract the iron. The chemical nature of the changes taking place during the extraction were not understood; in particular, the importance of carbon to the metal's hardness. Practices varied widely in different parts of the world. There is evidence, for example, that the Chinese were able to melt and cast iron implements very early, and that the Japanese produced amazing results with steel in small amounts, as evidenced by heirloom swords dating back centuries. Similar breakthroughs were made in the Middle East and India, but the processes never emerged into the rest of the world. For centuries the Europeans lacked methods for heating iron to the melting point at all. To produce iron, they slowly burned iron ore with wood in a clay-lined oven. The iron separated from the surrounding rock but never quite melted. Instead, it formed a crusty slag which was removed by hammering. This repeated heating and hammering process mixed oxygen with the iron oxide to produce iron, and removed the carbon from the metal. The result was nearly pure iron, easily shaped with hammers and tongs but too soft to take and keep a good edge. Because the metal was shaped, or wrought, by hammering, it came to be called wrought iron.

Tools and weapons brought back to Europe from the East were made of an iron that had been melted and cast into shape. Retaining more carbon, cast iron is harder than wrought iron and will hold a cutting edge. However, it is also more brittle than wrought iron. The European iron workers knew the Easterners had better iron, but not the processes involved in fashioning stronger iron products. Entire nations launched efforts to discover the process.

The first known European breakthrough in the production of cast iron, which led quickly to the first practical steel, did not come until 1740. In that year, Benjamin Huntsman took out a patent for the melting of material for the production of steel springs to be used in clockmaking. Over the next 20 years or so, the procedure became more widely adopted. Huntsman used a blast furnace to melt wrought iron in a clay crucible. He then added carefully measured amounts of pure charcoal to the melted metal. The resulting alloy was both strong and flexible when cast into springs. Since Huntsman was originally interested only in making better clocks, his crucible steel led directly to the development of nautical chronometers, which, in turn, made global navigation possible by allowing mariners to precisely determine their east/west position. The fact that he had also invented modern metallurgy was a side-effect which he apparently failed to notice.

Raw Materials

The raw materials used to produce pig iron in a blast furnace are iron ore, coke, sinter, and limestone. Iron ores are mainly iron oxides and include magnetite, hematite, limonite, and many other rocks. The iron content of these ores ranges from 70% down to 20% or less. Coke is a substance made by heating coal until it becomes almost pure carbon. Sinter is made of lesser grade, finely divided iron ore which, is roasted with coke and lime to remove a large amount of the impurities in the ore. Limestone occurs naturally and is a source of calcium carbonate.

Other metals are sometimes mixed with iron in the production of various forms of steel, such as chromium, nickel, manganese, molybdenum, and tungsten.

The Ore Extraction and Refining Process

Before iron ore can be used in a blast furnace, it must be extracted from the ground and partially refined to remove most of the impurities.

Extraction

• Much of the world's iron ore is extracted through open pit mining in which the surface of the ground is removed by heavy machines, often over a very large area, to expose the ore beneath. In cases where it is not economical to remove the surface, shafts are dug into the earth, with side tunnels to follow the layer of ore.

Refining

• The mined ore is crushed and sorted. The best grades of ore contain over 60% iron. Lesser grades are treated, or refined, to remove various contaminants before the ore is shipped to the blast furnace. Collectively, these refining methods are called beneficiation and include further crushing, washing with water to float sand and clay away, magnetic separation, pelletizing, and sintering. As more of the world's known supply of high iron content ore is depleted, these refining techniques have become increasingly important.
• The refined ore is then loaded on trains or ships and transported to the blast furnace site.

The Manufacturing
Process

Charging the blast furnace

• After processing, the ore is blended with other ore and goes to the blast furnace. A blast furnace is a tower-shaped structure, made of steel, and lined with refractory, or heat-resistant bricks. The mixture of raw material, or charge, enters at the top of the blast furnace. At the bottom of the furnace, very hot air is blown, or blasted, in through nozzles called tuye'res. The coke burns in the presence of the hot air. The oxygen in the air reacts with the carbon in the coke to form carbon monoxide. The carbon monoxide then reacts with the iron ore to form carbon dioxide and pure iron.

Separating the iron from the slag

• The melted iron sinks to the bottom of the furnace. The limestone combines with the rock and other impurities in the ore to form a slag which is lighter than the iron and floats on top. As the volume of the charge is reduced, more is continually added at the top of the furnace. The iron and slag are drawn off separately from the bottom of the furnace. The melted iron might go to a further alloying process, or might be cast into ingots called pigs. The slag is carried away for disposal.

Treating the gases

• The hot gases produced in the chemical reactions are drawn off at the top and routed to a gas cleaning plant where they are cleaned, or scrubbed, and sent back into the furnace; the remaining carbon monoxide, in particular, is useful to the chemical reactions going on within the furnace.

  A blast furnace normally runs day and night for several years. Eventually the brick lining begins to crumble, and the furnace is then shut down for maintenance.

Quality Control

The blast furnace operation is highly instrumented and is monitored continuously. Times and temperatures are checked and recorded. The chemical content of the iron ores received from the various mines are checked, and the ore is blended with other iron ore to achieve the desired charge. Samples are taken from each pour and checked for chemical content and mechanical properties such as strength and hardness.

Byproducts/Waste

There are a great many possible environmental effects from the iron industry. The first and most obvious is the process of open pit mining. Huge tracts of land are stripped to bare rock. Today, depleted mining sites are commonly used as landfills, then covered over and landscaped. Some of these landfills themselves become environmental problems, since in the recent past, some were used for the disposal of highly toxic substances which leached into soil and water.

The process of extracting iron from ore produces great quantities of poisonous and corrosive gases. In practice, these gases are scrubbed and recycled. Inevitably, however, some small amounts of toxic gases escape to the atmosphere.

A byproduct of iron purification is slag, which is produced in huge amounts. This material is largely inert, but must still be disposed of in landfills.

Ironmaking uses up huge amounts of coal. The coal is not used directly, but is first reduced to coke which consists of almost pure carbon. The many chemical byproducts of coking are almost all toxic, but they are also commercially useful. These products include ammonia, which is used in a vast number of products; phenol, which is used to make plastics, cutting oils, and antiseptics; cresols, which go into herbicides, pesticides, pharmaceuticals, and photographic chemicals; and toluene, which is an ingredient in many complex chemical products such as solvents and explosives.

Scrap iron and steel—in the form of old cars, appliances and even entire steel-girdered buildings—are also an environmental concern. Most of this material is recycled, however, since steel scrap is an essential resource in steelmaking. Scrap which isn't recycled eventually turns into iron oxide, or rust, and returns to the ground.

The Future

On the surface, the future of iron production—especially in the United States—appears troubled. Reserves of high-quality ore have become considerably depleted in areas where it can be economically extracted. Many long-time steel mills have closed.

However, these appearances are deceiving. New ore-enrichment techniques have made the use of lower-grade ore much more attractive, and there is a vast supply of that ore. Many steel plants have closed in recent decades, but this is largely because fewer are needed. The efficiency of blast furnaces alone has improved remarkably. At the beginning of this century, the largest blast furnace in the United States produced 644 tons of pig iron a day. It is believed that soon the possible production of a single furnace will reach 4,000 tons per day. Since many of these more modern plants have been built overseas, it has actually become more economical in some cases to ship steel across the ocean than to produce it in older U.S. plants.

Where To Learn More

Books

Lambert, Mark. Spotlight on Iron and Steel. Rourke Enterprises, 1988.

Hartley, Edward N. Iron and Steel Works of the World. International Publication, 1987.

Lewis, W. David. Iron and Steel in America. Hagley Museum, 1986.

Walker, R. D. Modern Ironmaking Methods. Gower Publication, 1986.

[Article by: Joel Simon]

A chemical element, Fe, atomic number 26, and atomic weight 55.847. Iron is the fourth most abundant element in the crust of the Earth (5%). It is a malleable, tough, silver-gray, magnetic metal. It melts at 1540°C, boils at 2800°C, and has a density of 7.86 g/cm³. The four stable, naturally occurring isotopes have masses of 54, 56, 57, and 58. The two main ores are hematite, Fe₂O₃, and limonite, Fe₂O₃ · 3H₂O. Pyrites, FeS₂, and chromite, Fe(CrO₂)₂, are mined as ores for sulfur and chromium, respectively. Iron is found in many other minerals, and it occurs in groundwaters and in the red hemoglobin of blood. See also Periodic table.

The greatest use of iron is for structural steels; cast iron and wrought iron are made in quantity, also. Magnets, dyes (inks, blueprint paper, rouge pigments), and abrasives (rouge) are among the other uses of iron and iron compounds.

There are several allotropic forms of iron. Ferrite or α-iron is stable up to 760°C (1400°F). The change of β-iron involves primarily a loss of magnetic permeability because the lattice structure (body-centered cubic) is unchanged. The allotrope called γ-iron has the cubic close-packed arrangements of atoms and is stable from 910 to 1400°C (1670 to 2600°F). Little is known about δ-iron except that it is stable above 1400°C (2600°F) and has a lattice similar to that of α-iron.

The metal is a good reducing agent and, depending on conditions, can be oxidized to the 2+, 3+, or 6+ state. In most iron compounds, the ferrous ion, iron(II), or ferric ion, iron(III), is present as a distinct unit. Ferrous compounds are usually light yellow to dark green-brown in color; the hydrated ion, Fe(H₂O)₆²⁺, which is found in many compounds and in solution, is light green. This ion has little tendency to form coordination complexes except with strong reagents such as cyanide ion, polyamines, and porphyrins. The ferric ion, because of its high charge (3+) and its small size, has a strong tendency to hold anions. The hydrated ion, Fe(H₂O)₆³⁺, which is found in solution, combines with OH⁻, F⁻, Cl⁻, CN⁻, SCN⁻, N₃⁻, C₂O₄²⁻, and other anions to form coordination complexes. See also Coordination chemistry.

An interesting aspect of iron chemistry is the array of compounds with bonds to carbon. Cementite, Fe₃C, is a component of steel. The cyanide complexes of both ferrous and ferric iron are very stable and are not strongly magnetic in contradistinction to most iron coordination complexes. The cyanide complexes form colored salts. See also Transition elements.

An essential mineral. The average adult contains 4-5 g of iron, of which 60-70% is present in the blood as haem in the circulating haemoglobin, and the remainder present in myoglobin in muscles, a variety of enzymes, and tissue stores. Iron is stored in the liver as ferritin, in other tissues as haemosiderin, and as the blood transport protein transferrin.

Iron balance: losses in faeces 0.3-0.5 mg per day, in sweat and skin cells 0.5 mg, traces in hair and urine, total loss 0.5-1.5 mg per day. Blood loss leads to a considerable loss of iron. The average diet contains 10-15 mg, of which 0.5-1.5 mg is absorbed. The haem iron of meat and fish is considerably better absorbed than the inorganic iron of vegetable foods. Reference intakes are 8.7 mg for adult men and 14.8 mg for women; women who have heavy menstrual blood losses may not be able to obtain enough from food, and supplements are necessary.

Absorption of iron is aided by vitamin C taken at the same time as iron-containing foods, and reduced by calcium, phosphate and phytic acid. Iron content of foods per 100 g: liver 6-14 mg, cereals up to 9 mg, nuts 1-5 mg, eggs 2-3 mg, meat 2-4 mg. Iron is added to flour so that it contains not less than 1.65 mg per 100 g. Fortified cereals provide 35% of the iron of British diets. Prolonged deficiency gives rise to anaemia.

Iron is essential to good health. Most iron in the body is contained in haemoglobin and myoglobin, the red pigments that carry oxygen. It also occurs as part of enzymes involved in energy production. A deficiency of iron results in anaemia, a lowering of haemoglobin concentration in the blood. The muscles and tissues are starved of vital oxygen, we feel tired and lethargic, and less inclined to exercise. Other more specific problems may include a sore tongue, cracks at the corner of the mouth, and nails that lack their usual pink flare. Heavy endurance training and bleeding (including menstrual bleeding) can increase the risk of iron deficiency and the need for iron therapy (increased iron intake by dietary adjustment and supplementation). Ten to fifteen percent of women between the ages of 13 and 45 lose more iron in menstrual bleeding than they acquire throughout the month from foods. Therefore, they probably require iron supplements to prevent iron deficiency.

The best sources of iron are meats, legumes, and watercress. Watercress and some other vegetables may have higher concentrations of iron than some meats, but iron from meat is mainly haem iron, which is easier to absorb than non-haem iron. Meat also contains a factor (not yet identified, but named MFP factor) that increases by four times the absorption of non-haem iron from other foods eaten with the meat. Cooking with traditional cast iron pans or a steel wok significantly increases the iron content of food as the surface releases fine particles, but little (if any) of this iron is absorbed. Vitamin C improves iron absorption, while tannic acid in teas, and phytic acid in many vegetables, interfere with it. (This is why you are advised not to drink large volumes of strong tea with a meal.) Large doses of other minerals (particularly calcium, copper, and zinc) in supplements may also reduce absorption. The recommended daily intake varies, but is about 8-10 mg for men and 15 mg for women of child-bearing age, increasing in physically active people.

Too much iron is toxic. It can damage the liver, heart, and pancreas, and irritate the stomach and gut, causing constipation or diarrhoea. If you take iron supplements, therefore, you should be careful not to overload your body.

noun

Something that physically confines the legs or arms. bond, chain (used in plural), fetter, handcuff (often used in plural), hobble, manacle, restraint, shackle. Archaic gyve. See free/unfree.

adjective

1. Full of vigor: able-bodied, lusty, red-blooded, robust, strapping, sturdy, vigorous, vital. See strong/weak.
2. Firmly, often unreasonably immovable in purpose or will: adamant, adamantine, brassbound, die-hard, grim, implacable, incompliant, inexorable, inflexible, intransigent, obdurate, relentless, remorseless, rigid, stubborn, unbendable, unbending, uncompliant, uncompromising, unrelenting, unyielding. Idioms: stubborn as amuleox. See resist/yield.

verb

To smooth by applying heat and pressure: mangle², press. See smooth/rough.

Idioms beginning with iron:
iron out
irons in the fire, too many

See also pump iron; strike while the iron's hot.

Definition: hard, tough; inflexible
Antonyms: flexible, soft, weak

Hardware, especially older and larger hardware of mainframe class with big metal cabinets housing relatively low-density electronics (but the term is also used of modern supercomputers). Often in the phrase big iron. Oppose silicon. See also dinosaur.

A common metallic element essential for the synthesis of hemoglobin. Its atomic number is 26 and its atomic weight is 55.85. Normal blood levels of iron range between 60 and 190 micrograms.

Description

Iron is a mineral that the human body uses to produce the red blood cells (hemoglobin) that carry oxygen throughout the body. It is also stored in myoglobin, an oxygen-carrying protein in the muscles that fuels cell growth.

General Use

Iron is abundant in red meats, vegetables, and other foods, and a well-balanced diet can usually provide an adequate supply of the mineral. But when there is insufficient iron from dietary sources, or as a result of blood loss in the body, the amount of hemoglobin in the bloodstream is reduced and oxygen cannot be efficiently transported to tissues and organs throughout the body. The resulting condition is known as iron-deficiency anemia, and is characterized by fatigue, shortness of breath, pale skin, concentration problems, dizziness, a weakened immune system, and energy loss.

Iron-deficiency anemia can be caused by a number of factors, including poor diet, heavy menstrual cycles, pregnancy, kidney disease, burns, and gastrointestinal disorders. Individuals with iron-deficiency anemia should always undergo a thorough evaluation by a physician to determine the cause.

Children two years old and under also need adequate iron in their diets to promote proper mental and physical development. Children under two who are not breastfed should eat iron-fortified formulas and cereals. Women who breastfeed need at least 15 mg of dietary or supplementary iron a day in order to pass along adequate amounts of the mineral to their child in breast milk. Parents should consult a pediatrician or other healthcare professional for guidance on iron supplementation in children.

It has been theorized that excess stored iron can lead to atherosclerosis and ischemic heart disease. Phlebotomy, or blood removal, has been used to reduce stored iron in patients with iron overload with some success. Iron chelation with drugs such as desferrioxamine (Desferal) that help patients excrete excess stores of iron can be helpful in treating iron overload caused by multiple blood transfusions.

Iron levels in the body are measured by both hemoglobin and serum ferritin blood tests.

Normal total hemoglobin levels are:

• neonates: 17-22 g/dl
• one week: 15-20 g/dl
• one month: 11-15 g/dl
• children: 11-13 g/dl
• adult males: 14-18 g/dl (12.4-14.9 g/dl after age 50)
• adult females: 12-16 g/dl (11.7-13.8 g/dl after menopause)

Normal serum ferritin levels are:

• neonates: 25-200 ng/ml
• one month: 200-600 ng/ml
• two to five months: 50-200 ng/ml
• six months to 15 years: 7-140 ng/ml
• adult males: 20-300 ng/ml
• adult females: 20-120 ng/ml

Preparations

Iron can be found in a number of dietary sources, including:

• pumpkin seeds
• dried fruits (apricots)
• lean meats (beef and liver)
• fortified cereals
• turkey (dark meat)
• green vegetables (spinach, kale, and broccoli)
• beans, peas, and lentils
• enriched and whole grain breads
• molasses
• sea vegetables (blue-green algae and kelp)

Eating iron-rich foods in conjunction with foods rich in vitamin C (such as citrus fruits) and lactic acid (sauerkraut and yogurt) can increase absorption of dietary iron. Cooking food in cast-iron pots can also add to their iron content.

The recommended dietary allowances (RDA) of iron as outlined by the United States Department of Agriculture (USDA) are as follows:

• Children 0–3: 6-10 mg/day
• children 4–10: 10 mg/day
• adolescent–adult males: 10 mg/day
• adolescent–adult females: 10-15 mg/day
• pregnant females: 30 mg/day
• breastfeeding females: 15 mg/day

A number of herbal remedies contain iron, and can be useful as a natural supplement. The juice of the herb stinging nettle (Urtica dioica) is rich in both iron and vitamin C (which is thought to promote the absorption of iron). It can be taken daily as a dietary supplement. Dandelion (Taraxacum officinale), curled dock (Rumex crispus), and parsley (Petroselinum crispum) also have high iron content, and can be prepared in tea or syrup form.

In Chinese medicine, dang gui (dong quai), or Angelica sinensis, the root of the angelica plant, is said to both stimulate the circulatory system and aid the digestive system. It can be administered as a decoction or tincture, and should be taken in conjunction with an iron-rich diet. Other Chinese remedies include foxglove root (Rehmannia glutinosa), Korean ginseng (Panax ginseng), and astragalus (Astragalus membranaceus).

Ferrum phosphoricum (iron phosphate), is used in homeopathic medicine to treat anemia. The remedy is produced by mixing iron sulfate, phosphate, and sodium acetate, which is administered in a highly diluted form to the patient. Other homeopathic remedies for anemia include Natrum muriaticum, Chinchona officinalis, Cyclamen europaeum, Ferrum metallicum, and Manganum aceticum. As with all homeopathic remedies, the type of remedy prescribed for iron deficiency depends on the individual's overall symptom picture, mood, and temperament. Patients should speak with their homeopathic professional or physician, or healthcare professional before taking any of these remedies.

Iron is also available in a number of over-the-counter supplements (i.e., ferrous fumerate, ferrous sulfate, ferrous gluconate, iron dextran). Both heme iron and nonheme iron supplements are available. Heme iron is more efficiently absorbed by the body, but non-heme iron can also be effective if used in conjunction with vitamin C and other dietary sources of heme iron. Some multivitamins also contain supplementary iron. Ingesting excessive iron can be toxic, and may have long-term negative effects. For this reason, iron supplements should be taken only under the recommendation and supervision of a doctor.

Precautions

Iron deficiency can be a sign of a more serious problem, such as internal bleeding. Anyone suffering from iron-deficiency anemia should always undergo a thorough evaluation by a healthcare professional to determine the cause.

Iron overdose in children can be fatal, and is a leading cause of poisoning in children. Children should never take supplements intended for adults, and should receive iron supplementation only under the guidance of a physician.

Individuals with chronic or acute health conditions, including kidney infection, alcoholism, liver disease, rheumatoid arthritis, asthma, heart disease, colitis, and stomach ulcer should consult a physician before taking herbal or pharmaceutical iron supplements.

If individuals taking homeopathic dilutions of ferrum phosphoricum experience worsening of their symptoms (known as a homeopathic aggravation), they should stop taking the remedy and contact their healthcare professional. A homeopathic aggravation can be an early indication that a remedy is working properly, but it can also be a sign that a different remedy is needed.

Patients diagnosed with hemochromatosis, a genetic condition in which the body absorbs too much iron and stores the excess in organs and tissues, should never take iron supplements.

Side Effects

Taking herbal or pharmaceutical iron supplements on an empty stomach may cause nausea. Iron supplementation may cause hard, dark stools, and individuals who take iron frequently experience constipation. Patients who experience dark bowel movements accompanied by stomach pains should check with their doctor, as this can also indicate bleeding in the digestive tract.

Other reported side effects include stomach cramps and chest pain. These symptoms should be evaluated by a physician if they occur.

Some iron supplements, particularly those taken in liquid form, may stain the teeth. Taking these through a straw, or with a dropper placed towards the back of the throat, may be helpful in preventing staining. Toothpaste containing baking soda and/or hydrogen peroxide can be useful in removing iron stains from teeth.

Signs of iron overdose include severe vomiting, racing heart, bloody diarrhea, stomach cramps, bluish lips and fingernails, pale skin, and weakness. If overdose is suspected, the patient should contact poison control and/or seek emergency medical attention immediately.

Interactions

Iron supplements may react with certain medications, including antacids, acetohydroxamic acid (Lithostat), dimercaprol, etidronate, fluoroquinolones. In addition, they can decrease the effectiveness of certain tetracyclines (antibiotics). Individuals taking these or any other medications should consult their healthcare professional before starting iron supplements.

Certain foods decrease the absorption of iron, including some soy-based foods, foods with large concentrations of calcium, and beverages containing caffeine and tannin (a substance found in black tea). These should not be taken within two hours of using an iron supplement. Some herbs also contain tannic acid, and should be avoided during treatment with iron supplements. These include allspice (Pimenta dioica) and bayberry (Myrica cerifera, also called wax myrtle).

Individuals considering treatment with homeopathic remedies should also consult their healthcare professional about possible interactions with certain foods, beverages, prescription medications, aromatic compounds, and other environmental elements—factors known in homeopathy as remedy antidotes—that could counteract the efficacy of treatment for iron deficiency.

Resources

Books

Medical Economics Company. PDR 2000 Physicians' Desk Reference. Montvale, NJ: Medical Economics Company, 1998.

Medical Economics Company. PDR for Herbal Medicines. Montvale, NJ: Medical Economics Company, 1998.

Ody, Penelope. The Complete Medicinal Herbal. New York: DK Publishing, 1993.

Periodicals

de Valk, B., and J.J.M. Marx. "Iron, Atherosclerosis, and Is-chemic Heart Disease." Archives of Internal Medicine 159(i14): 1542.

[Article by: Paula Ford-Martin]

Iron is a vital component of heme, the component of hemoglobin that transports oxygen in the blood. Iron deficiency is the world's most common cause of anemia (blood with low hemoglobin and red blood cell components). While some plants have modest amounts of iron (e.g., spinach), meat (red or white) has many times more iron than plants. Meat iron is also absorbed much more efficiently than plant iron. In addition to oxygen transport, iron and heme are key to normal brain development. Iron deficiency during the first six months of life can irreversibly impair cognitive development.

(SEE ALSO: Hematocrit; Hemoglobin)

Bibliography

Bridges, K. R. (2000). "Iron Deficiency." In Coun's Current Therapy, ed. R. E. Rakel. Philadelphia, PA: W. B. Saunders Company.

— KENNETH R. BRIDGES

ˈīǝrn n. 1. (irons) fetters or handcuffs.

2. informal a handgun.

in irons

1. having the feet or hands fettered.

2. (of a sailing vessel) stalled head to wind and unable to come about or tack either way.

See the Introduction, Abbreviations and Pronunciation for further details.

For more information on iron, visit Britannica.com.

One of the fortified cities of Naphtali (Josh 19:38). The name is preserved in the village of Yarun in Upper Galilee, today inside Lebanon. It is situated on a hill 2,400 feet (700 m) above sea level, 3 miles (5 km) south of Bint Jebeil.

Concordance
Josh 19:38

The power of iron to repel evil is very well attested in English folklore, and throughout Europe—all sorts of domestic objects, and even lumps of scrap iron, were placed in homes, stables, and cowsheds as defences against withccraft and harmful fairies, or used in counterspells. Sharp ones were even more effective, and Herrick mentions ‘hooks and shears’ in stables, and knives in babies’ cradles (Hesperides (1648), nos. 890, 892). Redhot iron was a potent counterspell when milk was bewitched.

Touching iron, or merely saying ‘Touch iron!’ or ‘Cold iron!’, cancels the bad luck of breaking a taboo or seeing something ill-omened; it is not as widespread as touching wood, but some groups, such as fishermen, practise it keenly.

A picturesque 19th-century theory was that iron was first reputed magical in prehistoric times, because men using bronze or stone weapons feared those using iron swords; obviously, this is flimsy guesswork, there being no possible evidence for or against the idea.

A ductile metallic element from which pig iron and steel are made; used in its relatively crude form for making tools, castings, and so on. Also see bar iron, cast iron, malleable iron, ornamental iron, wrought iron.

A mineral element essential for health. It is a component of haemoglobin, myoglobin, cytochromes, and other chemicals involved in vital metabolic activities. Dietary sources of iron include red meat, liver, dried fruit, nuts, molasses, and legumes. The best sources contain haem iron (i.e. iron contained within haemoglobin) because it is easily absorbed from the intestine. Vitamin C improves iron absorption, but tannic acid (e.g. in tea) and phytates (e.g. in wholemeal bread) interfere with it. Excessively high iron intakes can damage the liver, heart, and pancreas. Iron deficiency may lead to anaemia, decreased oxygen transport, and feelings of lassitude. Athletes training very strenuously may require higher than normal iron intakes to avoid iron deficiency, but supplementation of iron in those who are not deficient seems to have no benefit. Taking excessive amounts of iron supplements may be dangerous. It can result in serum ferritin levels being so high that not all the iron is maintained within cells or bound to proteins. If so, the excess iron can deposit in various tissues leading to organ dysfunction.

Iron is the second most abundant mineral on earth and is an essential nutrient for nearly all organisms. Iron is necessary for many varied functions in mammals, including the synthesis of DNA, the generation of energy from macronutrients by aerobic respiration, and the transport and metabolism of oxygen. Iron is highly reactive and is potentially toxic at high levels of intake; therefore, its utilization and storage present a major challenge for biological systems. Cellular iron exists primarily in its reduced ferrous (Fe⁺²) and oxidized ferric (Fe⁺³) states, and conversion of the mineral between these states serves to catalyze many reactions. One example is Fenton's reaction, whereby hydrogen peroxide is converted to highly reactive hydroxyl radicals (.OH).

An ancient observation on the occult virtues of iron was made by Pliny the Elder (ca. 23-79 C.E.) in his Natural History (as translated in 1601 by Philemon Holland).

"As touching the use of Yron and steele in Physicke, it serveth otherwise than for to launce, cut and dismember withal; for take the knife or dagger, an make an ymaginerie circle two or three times round with the point thereof upon a young child or an elder bodie, and then goe round withall about the partie as often, it is a singular preservative against all poysons, sorceries, or enchantments. Also to take any yron naile out of the coffin or sepulchre wherein man or woman lieth buried, and to sticke the same fast to the lintle or side post of a dore, leading either to the house or bed-chamber where any dooth lie who is haunted with Spirits in the night, he or she shall be delivered and secured from such phanasticall illusions. Moreover, it is said, that if one be lightly pricked with the point of sword or dagger, which hath been the death of a man, it is an excellent remedy against the pains of sides or breast, which come with sudden prickes or stitches."

In certain parts of Scotland and Ireland, there was a belief in the potency of iron for warding off the attacks of fairies. An iron poker, laid across a cradle, would, it was believed, keep fairies away until the child was baptized. The Reverend John G. Campbell in his Superstitions of the Highlands and Islands of Scotland (1900) relates how, when children, he and another boy were believed to be protected from a fairy that had been seen at a certain spot because one boy possessed a knife and the other a nail.

Many other countries had folklore about iron as a religious taboo or a charm against witchcraft and the supernatural. Iron tools were prohibited in Greek and Hebrew temples in ancient times. In Korea the body of the king was never to be touched by iron. Roman priests were forbidden to shave with iron blades. In India and China evil spirits were warded off by iron.

Sources:

French, Roger. Science in the Early Roman Empire: Pliny the Elder, His Sources and His Influence. New York: Barnes & Nobel, 1986.

Pliny the Elder. Natural History. New York: Penguin, 1991.

Environment

In meteorites and rarely in basalt.

Practically unknown in crystals, and rare except in meteorites. Sometimes found in large masses in basalt or smaller disseminated grains, rarely in placers in nuggets (as josephinite, a nickel-iron alloy).

Steel gray. Luster metallic; hardness 4-5; specific gravity 7.3-7.8; fracture hackly; cleavage cubic, also has distinct partings parallel to the cube and dodecahedron. Magnetic.

Iron, usually with some nickel. In meteorites nickel may be abundant.

Magnetic, easily soluble in acids with rusty residue on evaporation.

Native iron is so rare that its few sources are well known, one in Germany, and one on an island in the Arctic. Masses of iron from slag are often mistaken for meteorites. A suspected meteorite should be tested for nickel (see millerite, p. 117), after the presence of iron has been shown by a magnet or a compass. A polished surface is then acid-etched to bring out a crystal pattern, known as Widmanstaetten lines, for final confirmation.

Because of its easy oxidation (rust), native iron is naturally most uncommon. It has been found in disseminated grains in a basalt in Bühl, northwest of Kassel, Germany, and in masses of considerable size once thought to be meteorites at Disko I., Greenland. Iron-nickel alloy nuggets are found in gold placers in New Zealand, Oregon, and British Columbia. Native iron is found in meteorites, which range from pure metal to stone with small percentages of metal. The nickel content roughly determines the crystal texture and the pattern that is brought out by etching with dilute nitric acid.

Tremendous numbers of meteorites fall, though most burn up in the sky. Few reach the earth, and fewer yet are found. Fewer in number, iron meteorites are more often recognized than the stones. There is usually a crust on a fresh meteorite from the dissipation of heat on the surface during its fall. In their passage through the air, meteorites are never actually melted; they never contain cavities, enclose pebbles, or make casts of objects they hit. They are most often confused with concretions of various sorts, with pyrite balls, and with corroded rocks; but none of these is ever magnetic.

A chemical element, atomic number 26, atomic weight 55.847, symbol Fe. Iron is chiefly important to the animal body because it is the main constituent of hemoglobin, cytochrome, and other components of respiratory enzyme systems. A constant although small intake of iron in food is needed to replace erythrocytes that are destroyed in the body processes.

• i.-59 — a radioisotope of iron having a half-life of 45 days; used in ferrokinetics tests to determine the rate at which iron is cleared from the plasma and incorporated in red cells. Symbol ⁵⁹Fe.
• i. binding — absorbed iron is rapidly and tightly bound to a specific transport protein, transferrin or siderophilin, from which it is discharged at iron receptor sites in the bone marrow.
• i. dextran — an injectable form of iron used in the prevention of iron deficiency. See iron poisoning (below).
• i. galactan — used as an injection vehicle for iron in young piglets.
• i. nutritional deficiency — is most common in piglets raised on sows kept indoors under artificial conditions. Clinical signs are pallor, dyspnea, edema of the head and a secondary diarrhea.
• organic i. poisoning — see iron poisoning (below).
• i. overload — storage of excessive iron in body tissues such as occurs in human idiopathic hemochromatosis is not recorded in animals, but overload may occur as a result of excessive therapy.
• i. poisoning — overdosing piglets with iron compounds by mouth causes diarrhea and death. Organic iron preparations, usually dextrans, injected in piglets can cause deaths acutely, within an hour or two of injection. At postmortem examination there is myonecrosis of skeletal muscle. Deaths have also occurred within a few minutes of intramuscular injection of organic iron preparations in horses. Sudden death due to massive liver damage also recorded in newborn foals dosed orally with ferrous fumarate with or without yeast in a paste. Asymmetry of the hindquarters in pigs is also recorded as a sequel of intramuscular injections of iron. See also asymmetric hind quarter syndrome. Bore water often contains significant levels of iron and when used for fish culture in dams may cause mortalities.
• i. pool — a source of readily available iron for metabolic emergencies, probably located in the bone marrow.
• i. storage disease — hemochromatosis.
• i.-sulfur proteins — polypeptides that contain iron-sulfur centers capable of Fe₂S₂ or Fe₄S₄ stoichiometry and with standard reduction potential between NAD+ and ubiquinone. Critical components of many electron transport chains, e.g. in oxidative phosphorylation and photosynthesis.
• total i.-binding capacity — the serum iron plus the unbound iron-binding capacity of the serum.
• i. turnover — see iron turnover.
• unbound i.-binding capacity — that portion of the plasma transferrin molecule that is not bound to Fe³+.
• i.-yeast paste — highly hepatoxic in some newborn foals when fed as a dietary supplement.

An element with atomic number 26; symbol: Fe. Iron is one of the most abundant elements in the rocky planets. It is the most abundant element in the metallic cores of the inner planets.

A nutrient needed for the manufacture of chlorophyll. Plants in alkaline soils may not be able to absorb iron, resulting in chlorosis of their leaves.

Iron is associated with strength and willpower (an iron will), which may play into the meaning of a dream in which iron is explicitly a part.

"Fe" redirects here. For other uses, see Fe (disambiguation).

This article is about the chemical element. For other uses, see Iron (disambiguation).

manganese ← iron → cobalt - ↑ Fe ↓ Ru 26Fe Periodic table
Appearance
lustrous metallic with a grayish tinge
General properties
Name, symbol, number	iron, Fe, 26
Element category	transition metal
Group, period, block	8, 4, d
Standard atomic weight	55.845(2) g·mol−1
Electron configuration	[Ar] 3d6 4s2
Electrons per shell	2, 8, 14, 2 (Image)
Physical properties
Phase	solid
Density (near r.t.)	7.874 g·cm−3
Liquid density at m.p.	6.98 g·cm−3
Melting point	1811 K, 1538 °C, 2800 °F
Boiling point	3134 K, 2862 °C, 5182 °F
Heat of fusion	13.81 kJ·mol−1
Heat of vaporization	340 kJ·mol−1
Specific heat capacity	(25 °C) 25.10 J·mol−1·K−1
Vapor pressure
P/Pa 1 10 100 1 k 10 k 100 k at T/K 1728 1890 2091 2346 2679 3132
Atomic properties
Electronegativity	1.83 (Pauling scale)
Ionization energies (more)	1st: 762.5 kJ·mol−1
	2nd: 1561.9 kJ·mol−1
	3rd: 2957 kJ·mol−1
Atomic radius	126 pm
Covalent radius	132±3 (low spin), 152±6 (high spin) pm
Miscellanea
Magnetic ordering	ferromagnetic
	1043 K
Electrical resistivity	(20 °C) 96.1 nΩ·m
Thermal conductivity	(300 K) 80.4 W·m−1·K−1
Thermal expansion	(25 °C) 11.8 µm·m−1·K−1
Speed of sound (thin rod)	(r.t.) (electrolytic) 5120 m·s−1
Young's modulus	211 GPa
Shear modulus	82 GPa
Bulk modulus	170 GPa
Poisson ratio	0.29
Mohs hardness	4
Vickers hardness	608 MPa
Brinell hardness	490 MPa
CAS registry number	7439-89-6
Most stable isotopes
Main article: Isotopes of iron
iso NA half-life DM DE (MeV) DP 54Fe 5.8% >3.1×1022y 2ε capture  ? 54Cr 55Fe syn 2.73 y ε capture 0.231 55Mn 56Fe 91.72% 56Fe is stable with 30 neutrons 57Fe 2.2% 57Fe is stable with 31 neutrons 58Fe 0.28% 58Fe is stable with 32 neutrons 59Fe syn 44.503 d β− 1.565 59Co 60Fe syn 2.6×106 y β− 3.978 60Co
This box: view • talk • edit

Iron (pronounced /ˈаɪ.ərn/) is a metallic chemical element with the symbol Fe (Latin: ferrum) and atomic number 26. Iron is a group 8 and period 4 element and is therefore classified as a transition metal. Iron and iron alloys (steels) are by far the most common metals and the most common ferromagnetic materials in everyday use. Fresh iron surfaces are lustrous and silvery-grey in color, but oxidize in air to form a red or brown coating of ferric oxide or rust. Pure single crystals of iron are soft (softer than aluminium), and the addition of minute amounts of impurities, such as carbon, significantly strengthens them. Alloying iron with appropriate small amounts (up to a few per cent) of other metals and carbon produces steel, which can be 1,000 times harder than pure iron.

Iron-56 is the heaviest stable isotope produced by the alpha process in stellar nucleosynthesis; heavier elements than iron and nickel require a supernova for their formation. Iron is the most abundant element in the core of red giants, and is the most abundant metal in iron meteorites and in the dense metal cores of planets such as Earth.

Contents 1 Characteristics 2 Mechanical properties 2.1 Allotropes 2.2 Occurrence 2.3 Isotopes 3 Chemistry and compounds 4 History 5 Industrial production 5.1 Blast furnace 5.2 Further processes 6 Applications 6.1 Elemental iron 6.2 Iron compounds 7 Biological role 7.1 Dietary sources 7.2 Regulation of uptake 8 Precautions 9 See also 10 References 11 Books 12 External links

Characteristics

Pure iron is a metal but is rarely found in this form on the surface of the earth because it oxidizes readily in the presence of oxygen and moisture. In order to obtain metallic iron, oxygen must be removed from naturally occurring ores by chemical reduction – mainly of the iron ore hematite (Fe₂O₃) by carbon at high temperature. The properties of iron can be modified by alloying it with various other metals (and some non-metals, notably carbon and silicon) to form steels.

Nuclei of iron atoms have some of the highest binding energies per nucleon, surpassed only by the nickel isotope ⁶²Ni. The universally most abundant of the highly stable nuclides is, however, ⁵⁶Fe. This is formed by nuclear fusion in stars. Although a further tiny energy gain could be extracted by synthesizing ⁶²Ni, conditions in stars are unsuitable for this process to be favoured. Elemental distribution on Earth greatly favours iron over nickel, and also presumably in supernova element production.^[1]

Iron (as Fe²⁺, ferrous ion) is a necessary trace element used by almost all living organisms. The only exceptions are several organisms that live in iron-poor environments and have evolved to use different elements in their metabolic processes, such as manganese instead of iron for catalysis, or hemocyanin instead of hemoglobin. Iron-containing enzymes, usually containing heme prosthetic groups, participate in catalysis of oxidation reactions in biology, and in transport of a number of soluble gases. See hemoglobin, cytochrome, and catalase.

Mechanical properties

Characteristic values of tensile strength (TS) and Brinell hardness (BH) of different forms of iron.^[2][3]

Material	TS (MPa)	BH (Brinell)
Iron whiskers	11000
Ausformed (hardened) steel	2930	850–1200
Martensitic steel	2070	600
Bainitic steel	1380	400
Pearlitic steel	1200	350
Cold-worked iron	690	200
Small-grain iron	340	100
Iron containing dissolved carbon	140	40
Single crystal of pure iron	10	3

Mechanical properties of iron and its alloys are traditionally evaluated using various measurements, such as Brinell test, Rockwell test, tensile strength and other; their results are so much consistent among each other that universal relations are often used to relate results of one measurement to another.^[3][4] Those measurements reveal that mechanical properties of iron crucially depend on purity: Purest research-purpose single crystals of iron are softer than aluminium. Addition of only 10 parts per million of carbon doubles their strength.^[2] The hardness increases rapidly with carbon content up to 0.2% and saturates at ~0.6%.^[5] The purest industrially produced iron (about 99.99% purity) has hardness of 20–30 Brinell ^[6]

Allotropes

Main article: Allotropes of iron

Iron represents perhaps the best-known example of allotropy in a metal. There are three allotropic forms of iron, known as α, γ and δ.

As molten iron cools down it crystallizes at 1538 °C into its δ allotrope, which has a body-centred cubic (bcc) crystal structure. As it cools further its crystal structure changes to face-centred cubic (fcc) at 1394 °C, when it is known as γ-iron, or austenite. At 912 °C the crystal structure again becomes bcc as α-iron, or ferrite, is formed, and at 770 °C (the Curie point, T_c) the iron becomes magnetic. As the iron passes through the Curie temperature there is no change in crystalline structure, but there is a change in "domain structure", where each domain contains iron atoms with a particular electronic spin. In unmagnetized iron, all the electronic spins of the atoms within one domain are in the same direction; however, in neighbouring domains they point in various directions and thus cancel out. In magnetized iron, the electronic spins of all the domains are all aligned, so that the magnetic effects of neighbouring domains reinforce each other. Although each domain contains billions of atoms, they are very small, about 10 microns across.

Iron is of most importance when mixed with certain other metals and with carbon to form steels. There are many types of steels, all with different properties; and an understanding of the properties of the allotropes of iron is key to the manufacture of good quality steels.

Alpha iron, also known as ferrite, is the most stable form of iron at normal temperatures. It is a fairly soft metal that can dissolve only a small concentration of carbon (no more than 0.021% by mass at 910 °C).^[7]

Above 912 °C and up to 1400 °C α-iron undergoes a phase transition from body-centred cubic to the face-centred cubic configuration of γ-iron, also called austenite. This is similarly soft and metallic but can dissolve considerably more carbon (as much as 2.04% by mass at 1146 °C). This form of iron is used in the type of stainless steel used for making cutlery, and hospital and food-service equipment.

Occurrence

See also: Category:Iron minerals

The red appearance of this water is due to ferric ion, Iron(III) or Fe³⁺, in the rocks.

Iron is the sixth most abundant element in the Universe, formed as the final act of nucleosynthesis, by silicon fusing in massive stars. While it makes up about 5% of the Earth's crust, the Earth's core is believed to consist largely of an iron-nickel alloy constituting 35% of the mass of the Earth as a whole. Iron is consequently the most abundant element on Earth, but only the fourth most abundant element in the Earth's crust.^[8] Most of the iron in the crust is found combined with oxygen as iron oxide minerals such as hematite and magnetite.

About 1 in 20 meteorites consist of the unique iron-nickel minerals taenite (35–80% iron) and kamacite (90–95% iron). Although rare, iron meteorites are the major form of natural metallic iron on the Earth's surface.

The red color of the surface of Mars is thought to derive from an iron oxide-rich regolith.

Isotopes

Main article: Isotopes of iron

Naturally occurring iron consists of four isotopes: 5.845% of radioactive ⁵⁴Fe (half-life: >3.1×10²² years), 91.754% of stable ⁵⁶Fe, 2.119% of stable ⁵⁷Fe and 0.282% of stable ⁵⁸Fe. ⁶⁰Fe is an extinct radionuclide of long half-life (1.5 million years).

Much of the past work on measuring the isotopic composition of Fe has centred on determining ⁶⁰Fe variations due to processes accompanying nucleosynthesis (i.e., meteorite studies) and ore formation. In the last decade however, advances in mass spectrometry technology have allowed the detection and quantification of minute, naturally occurring variations in the ratios of the stable isotopes of iron. Much of this work has been driven by the Earth and planetary science communities, although applications to biological and industrial systems are beginning to emerge.^[9]

The most abundant iron isotope ⁵⁶Fe is of particular interest to nuclear scientists. A common misconception is that this isotope represents the most stable nucleus possible, and that it thus would be impossible to perform fission or fusion on ⁵⁶Fe and still liberate energy. This is not true, as both ⁶²Ni and ⁵⁸Fe are more stable, being the most stable nuclei. However, since ⁵⁶Ni is much more easily produced from lighter nuclei in the alpha process in nuclear reactions in supernovae (see silicon burning process), nickel-56 (14 alpha particles) is the endpoint of fusion chains inside extremely massive stars, since addition of another alpha would result in zinc-60, which requires a great deal more energy. This nickel-56, which has a half-life of about 6 days, is therefore made in quantity in these stars, but soon decays by two successive positron emissions within supernova decay products in the supernova remnant gas cloud, to first radioactive cobalt-56, and then stable iron-56. This last nuclide is therefore common in the universe, relative to other stable metals of approximately the same atomic weight.

In phases of the meteorites Semarkona and Chervony Kut a correlation between the concentration of ⁶⁰Ni, the daughter product of ⁶⁰Fe, and the abundance of the stable iron isotopes could be found which is evidence for the existence of ⁶⁰Fe at the time of formation of the solar system. Possibly the energy released by the decay of ⁶⁰Fe contributed, together with the energy released by decay of the radionuclide ²⁶Al, to the remelting and differentiation of asteroids after their formation 4.6 billion years ago. The abundance of ⁶⁰Ni present in extraterrestrial material may also provide further insight into the origin of the solar system and its early history. Of the stable isotopes, only ⁵⁷Fe has a nuclear spin (–1/2).

Chemistry and compounds

Iron forms compounds mainly in the +2 and +3 oxidation states. Traditionally, iron(II) compounds have been called ferrous, and iron(III) compounds ferric. There are many compounds in each of the oxidation states (see Category:Iron compounds for a list); representative examples would include iron(II) sulfate (FeSO₄) and iron(III) chloride (FeCl₃). There are also numerous examples of compounds that contain iron atoms in both of these oxidation states, such as magnetite and prussian blue. The ferrate anion [FeO₄]²⁻ contains an iron(VI) centre, its highest known oxidation state, and is present, for example in potassium ferrate (K₂FeO₄). There are numerous organometallic compounds (such as iron pentacarbonyl) that contain formally zerovalent (or lower) iron.

History

This section requires expansion.

The symbol for Mars has been used since ancient times to represent iron.

The Delhi iron pillar is an example of the iron extraction and processing methodologies of India. The iron pillar at Delhi has withstood corrosion for the last 1600 years.

Main article: History of ferrous metallurgy

The first wrought iron used by mankind during prehistory came from meteors. The smelting of iron in bloomeries began in the second millennium BC. Artifacts from smelted iron occur in India from 1800–1200 BC.^[10] in the Levant from about 1500 BC (suggesting smelting in Anatolia or the Caucasus).^[11][12]

Cast iron was first produced in China about 550 BC,^[13] but not in Europe until the medieval period^{[citation needed]}. During the medieval period, means were found in Europe of producing wrought iron from cast iron (in this context known as pig iron) using finery forges. For all these processes, charcoal was required as fuel.

Steel (with smaller carbon content than pig iron but more than wrought iron) was first produced in antiquity. New methods of producing it by carburizing bars of iron in the cementation process were devised in the 17th century AD. In the Industrial Revolution, new methods of producing bar iron without charcoal were devised and these were later applied to produce steel. In the late 1850s, Henry Bessemer invented a new steelmaking process, involving blowing air through molten pig iron, to produce mild steel. This and other 19th century and later processes have led to wrought iron no longer being produced.

Industrial production

Iron ore pellets from Kiruna, Sweden.

See also: Iron ore

The production of iron or steel is a process unless the desired final product is cast iron. The first stage is to produce pig iron in a blast furnace. The second is to make wrought iron or steel from pig iron by a further process.

Blast furnace

Main article: Blast furnace

Ninety percent of all mining of metallic ores is for the extraction of iron. Industrially, iron is produced starting from iron ores, principally hematite (nominally Fe₂O₃) and magnetite (Fe₃O₄) by a carbothermic reaction (reduction with carbon) in a blast furnace at temperatures of about 2000 °C. In a blast furnace, iron ore, carbon in the form of coke, and a flux such as limestone (which is used to remove impurities in the ore which would otherwise clog the furnace with solid material) are fed into the top of the furnace, while a blast of heated air is forced into the furnace at the bottom.

Iron output in 2005

In the furnace, the coke reacts with oxygen in the air blast to produce carbon monoxide:

2 C + O₂ → 2 CO

The carbon monoxide reduces the iron ore (in the chemical equation below, hematite) to molten iron, becoming carbon dioxide in the process:

3 CO + Fe₂O₃ → 2 Fe + 3 CO₂

The flux is present to melt impurities in the ore, principally silicon dioxide sand and other silicates. Common fluxes include limestone (principally calcium carbonate) and dolomite (calcium-magnesium carbonate). Other fluxes may be used depending on the impurities that need to be removed from the ore. In the heat of the furnace the limestone flux decomposes to calcium oxide (quicklime):

CaCO₃ → CaO + CO₂

Then calcium oxide combines with silicon dioxide to form a slag.

CaO + SiO₂ → CaSiO₃

The slag melts in the heat of the furnace. In the bottom of the furnace, the molten slag floats on top of the denser molten iron, and apertures in the side of the furnace are opened to run off the iron and the slag separately. The iron once cooled, is called pig iron, while the slag can be used as a material in road construction or to improve mineral-poor soils for agriculture.^{[citation needed]}

How Iron was extracted in the 19th century

This heap of iron ore pellets will be used in steel production.

In 2005, approximately 1,544 million metric tons of iron ore were produced worldwide. China was the top producer of iron ore with at least one-fourth world share followed by Brazil, Australia and India, reports the British Geological Survey.

Further processes

Main articles: Steelmaking and Ironworks

Pig iron is not pure iron, but has 4–5% carbon dissolved in it with small amounts of other impurities like sulfur, magnesium, phosphorus and manganese. As the carbon is the major impurity, the iron (pig iron) becomes brittle and hard. This form of iron is used to cast articles in foundries such as stoves, pipes, radiators, lamp-posts and rails.

Alternatively pig iron may be made into steel (with up to about 2% carbon) or wrought iron (commercially pure iron). Various processes have been used for this, including finery forges, puddling furnaces, Bessemer converters, open hearth furnaces, basic oxygen furnaces, and electric arc furnaces. In all cases, the objective is to oxidize some or all of the carbon, together with other impurities. On the other hand, other metals may be added to make alloy steels.

The hardness of the steel depends upon its carbon content, the higher the proportion of carbon, the greater the hardness and the lesser the ductility. The properties of the steel can also be changed by tempering it. To harden the steel, it is heated to red hot and then cooled by quenching it in the water. It becomes harder and more brittle. This steel is then heated to a required temperature and allowed to cool. The steel thus formed is less brittle.

Applications

This article contains embedded lists that may be poorly defined, unverified or indiscriminate. Please help to clean it up to meet Wikipedia's quality standards. (March 2009)

Elemental iron

Iron is the most widely used of all the metals, accounting for 95% of worldwide metal production. Its low cost and high strength make it indispensable in engineering applications such as the construction of machinery and machine tools, automobiles, the hulls of large ships, and structural components for buildings. Since pure iron is quite soft, it is most commonly used in the form of steel. Some of the forms in which iron is produced commercially include:

• Pig iron has 3.5–4.5% carbon^[14] and contains varying amounts of contaminants such as sulfur, silicon and phosphorus. Its only significance is that of an intermediate step on the way from iron ore to cast iron and steel.
• Cast iron contains 2–4% carbon, 1–6% silicon, and small amounts of manganese. Contaminants present in pig iron that negatively affect material properties, such as sulfur and phosphorus, have been reduced to an acceptable level. It has a melting point in the range of 1420–1470 K, which is lower than either of its two main components, and makes it the first product to be melted when carbon and iron are heated together. Its mechanical properties vary greatly, dependent upon the form carbon takes in the alloy. "White" cast irons contain their carbon in the form of cementite, or iron carbide. This hard, brittle compound dominates the mechanical properties of white cast irons, rendering them hard, but unresistant to shock. The broken surface of a white cast iron is full of fine facets of the broken carbide, a very pale, silvery, shiny material, hence the appellation. In grey iron the carbon exists free as fine flakes of graphite, and also renders the material brittle due to the stress-raising nature of the sharp edged flakes of graphite. A newer variant of grey iron, referred to as ductile iron is specially treated with trace amounts of magnesium to alter the shape of graphite to spheroids, or nodules, vastly increasing the toughness and strength of the material.
  

  

  The fining process of smelting iron ore to make wrought iron from pig iron, with the right illustration displaying men working a blast furnace, from the Tiangong Kaiwu encyclopedia, published in 1637 by Song Yingxing.

• Wrought iron contains less than 0.25% carbon.^[14] It is a tough, malleable product, but not as fusible as pig iron. If honed to an edge, it loses it quickly. Wrought iron is characterized by the presence of fine fibres of slag entrapped in the metal. Wrought iron is more corrosion resistant than steel. It has been almost completely replaced by mild steel for traditional "wrought iron" products and blacksmithing. Mild steel corrodes more readily that wrought iron, but is cheaper and more widely available.
• Carbon steel contains 2.0% carbon or less,^[15] with small amounts of manganese, sulfur, phosphorus, and silicon.
• Alloy steels contain varying amounts of carbon as well as other metals, such as chromium, vanadium, molybdenum, nickel, tungsten, etc. Their alloy content raises their cost, and so they can usually only be justified for specialist uses. Recent developments in ferrous metallurgy have produced a growing range of microalloyed steels, also termed 'HSLA' or high-strength, low alloy steels, containing tiny additions to produce high strengths and often spectacular toughness at minimal cost.

The main disadvantage of iron and steel is that pure iron, and most of its alloys, suffer badly from rust if not protected in some way. Painting, galvanization, passivation, plastic coating and bluing are some techniques used to protect iron from rust by excluding water and oxygen or by sacrificial protection.

Iron compounds

Iron chloride hexahydrate

• Iron oxides (FeO, Fe₃O₄, and Fe₂O₃) are ores used for iron production (see bloomery and blast furnace). They are also used as a catalyst in the Space Shuttle Solid Rocket Boosters,^[16] and in the production of magnetic storage media in computers. They are often mixed with other compounds, and retain their magnetic properties in solution.
• Iron(II) acetate (Fe(CH₃CO₂)₂ (ferrous acetate) is used as a mordant in the dyeing of cloth and leather, and as a wood preservative.
• Iron(III) ammonium citrate (C₆H_5+4yFe_xN_yO₇) is used in blueprints.
• Iron(III) arsenate (FeAsO₄) is used in insecticides.
• Iron(III) chloride (FeCl₃) is used in water purification and sewage treatment, in the dyeing of cloth, as a colouring agent in paints, as an additive in animal feed, and as an etchant for copper in the manufacture of printed circuit boards.
• Iron(III) chromate (Fe₂(CrO₄)₃) is a yellow pigment for paints and ceramics.
• Iron(III) hydroxide (Fe(OH)₃) is used as a brown pigment for rubber and in water purification systems.
• Iron(III) phosphate (FePO₄) is used in fertilizers and as an additive in human and animal food.
• Iron(II) gluconate (Fe(C₆H₁₁O₇)₂) is used as a dietary supplement in iron pills.
• Iron(II) oxalate (FeC₂O₄) is used as yellow pigment for paints, plastics, glass and ceramics, and in photography.
• Iron(II) sulfate (FeSO₄) is used in water purification and sewage treatment systems, as a catalyst in the production of ammonia, as an ingredient in fertilizer, herbicide, and moss killer, as an additive in animal feed, in wood preservative, and as an additive to flour to increase nutritional iron levels. Experimental iron fertilization of areas of the ocean using iron(II) sulfate has proven successful in increasing plankton growth.^[17][18][19]

The use of iron compounds in organic synthesis is mainly for the reduction of nitro compounds.^[20] Additionally, iron has been used for desulfurizations,^[21] reduction of aldehydes,^[22] and the deoxygenation of amine oxides.^[23]

Biological role

Structure of Heme b

Main article: Human iron metabolism

Iron is essential to nearly all known organisms. In cells, iron is generally stored in the centre of metalloproteins, because "free" iron (which binds non-specifically to many cellular components) can catalyse production of toxic free radicals. Iron deficiency can lead to iron deficiency anemia.

In animals, plants, and fungi, iron is often the metal ion incorporated into the heme complex. Heme is an essential component of cytochrome proteins, which mediate redox reactions, and of oxygen carrier proteins such as hemoglobin, myoglobin, and leghemoglobin. Inorganic iron also contributes to redox reactions in the iron-sulfur clusters of many enzymes, such as nitrogenase (involved in the synthesis of ammonia from nitrogen and hydrogen) and hydrogenase. Non-heme iron proteins include the enzymes methane monooxygenase (oxidizes methane to methanol), ribonucleotide reductase (reduces ribose to deoxyribose; DNA biosynthesis), hemerythrins (oxygen transport and fixation in marine invertebrates) and purple acid phosphatase (hydrolysis of phosphate esters).

Iron distribution is heavily regulated in mammals, partly because iron has a high potential for biological toxicity^[24]. Iron distribution is also regulated because many bacteria require iron, so restricting its availability to bacteria (generally by sequestering it inside cells) can help to prevent or limit infections. This is probably the reason for the relatively low amounts of iron in mammalian milk. A major component of this regulation is the protein transferrin, which binds iron absorbed from the duodenum and carries it in the blood to cells.^[25]

Dietary sources

Good sources of dietary iron include red meat, fish, poultry, lentils, beans, leaf vegetables, tofu, chickpeas, black-eyed peas, fortified bread, and fortified breakfast cereals. Iron in low amounts is found in molasses, teff and farina. Iron in meat (haem iron) is more easily absorbed than iron in vegetables,^[26] but heme/hemoglobin from red meat has effects which may increase the likelihood of colorectal cancer.^[27][28]

Iron provided by dietary supplements is often found as iron (II) fumarate, although iron sulfate is cheaper and is absorbed equally well. Elemental iron, despite being absorbed to a much smaller extent (stomach acid is sufficient to convert some of it to ferrous iron), is often added to foods such as breakfast cereals or "enriched" wheat flour (where it is listed as "reduced iron" in the list of ingredients). Iron is most available to the body when chelated to amino acids - iron in this form is ten to fifteen times more bioavailable^[29] than any other, and is also available for use as a common iron supplement. Often the amino acid chosen for this purpose is the cheapest and most common amino acid, glycine, leading to "iron glycinate" supplements.^[30] The RDA for iron varies considerably based on age, gender, and source of dietary iron (heme-based iron has higher bioavailability).^[31] Infants may require iron supplements if they are bottle-fed cow's milk.^[32] Blood donors and pregnant women are at special risk of low iron levels and are often advised to supplement their iron intake.^{[citation needed]}

Regulation of uptake

Iron uptake is tightly regulated by the human body, which has no regulated physiological means of excreting iron. Only small amounts of iron are lost daily due to mucosal and skin epithelial cell sloughing, so control of iron levels is mostly by regulating uptake.^[33] Regulation of iron uptake is impaired in some people as a result of a genetic defect that maps to the HLA-H gene region on chromosome 6. In these people, excessive iron intake can result in iron overload disorders, such as hemochromatosis. Many people have a genetic susceptibility to iron overload without realizing it or being aware of a family history of the problem. For this reason, it is advised that people do not take iron supplements unless they suffer from iron deficiency and have consulted a doctor. Hemochromatosis is estimated to cause disease in between 0.3 and 0.8% of Caucasians.^[34]

MRI finds that iron accumulates in the hippocampus of the brains of those with Alzheimer's disease and in the substantia nigra of those with Parkinson disease.^[35]

Precautions

Main article: Iron poisoning

Large amounts of ingested iron can cause excessive levels of iron in the blood. High blood levels of free ferrous iron react with peroxides to produce free radicals, which are highly reactive and can damage DNA, proteins, lipids, and other cellular components. Thus, iron toxicity occurs when there is free iron in the cell, which generally occurs when iron levels exceed the capacity of transferrin to bind the iron. Damage to the cells of the gastrointestinal tract can also prevent them from regulating iron absorption leading to further increases in blood levels. Iron typically damages cells in the heart, liver and elsewhere, which can cause significant adverse effects, including coma, metabolic acidosis, shock, liver failure, coagulopathy, adult respiratory distress syndrome, long-term organ damage, and even death.^[36] Humans experience iron toxicity above 20 milligrams of iron for every kilogram of mass, and 60 milligrams per kilogram is considered a lethal dose.^[37] Over-consumption of iron, often the result of children eating large quantities of ferrous sulfate tablets intended for adult consumption, is one of the most common toxicological causes of death in children under six.^[37] The DRI lists the Tolerable Upper Intake Level (UL) for adults as 45 mg/day. For children under fourteen years old the UL is 40 mg/day.

The medical management of iron toxicity is complex, and can include use of a specific chelating agent called deferoxamine to bind and expel excess iron from the body.^[36][38]

See also

• El Mutún in Bolivia, where 20% of the world's accessible iron and magnesium is located.
• Iron Age
• Iron fertilization - Proposed fertilization of oceans to stimulate phytoplankton growth.
• Iron (metaphor)
• Iron in mythology
• List of countries by iron production
• Pelletising - Process of creation of iron ore pellets.
• Rustproof iron
• Specht Building - A historic landmark in Omaha, Nebraska utilizing an iron facade.

References

1. ^ "Iron and Nickel Abundances in H~II Regions and Supernova Remnants". June 14, 1995. http://www.aas.org/publications/baas/v27n2/aas186/abs/S3707.html. Retrieved 2008-05-21. .
2. ^ ^{a b} Walter H. Kohl (1995). Handbook of materials and techniques for vacuum devices. Springer. pp. 164–167. ISBN 1563963876. http://books.google.com/books?id=-Ll6qjWB-RUC&pg=PA164. 
3. ^ ^{a b} prepared under the direction of the ASM International Handbook Committee ; Howard Kuhn, Dana Medlin, volume editors. (2000). ASM Handbook – Mechanical Testing and Evaluation. 8. ASM International. p. 275. ISBN 0871703890. http://www.gorni.eng.br/e/Gorni_SFHTHandbook.pdf. 
4. ^ "Hardness Conversion Chart". http://mdmetric.com/tech/hardnessconversion.html. Retrieved 2009-07-07. 
5. ^ V. Raghavan (2004). Materials Science and Engineering. PHI Learning Pvt. Ltd.. p. 218. ISBN 8120324552. http://books.google.com/books?id=LgB5dkmPML0C&pg=PA218. 
6. ^ "Properties of Various Pure Irons : Study on pure iron I". Tetsu-to-Hagane 50 (1): 42–47. http://ci.nii.ac.jp/naid/110001459778/en. 
7. ^ John Wilson Martin (2007). Concise encyclopedia of the structure of materials. Elsevier. p. 183. ISBN 0080451276. http://books.google.com/books?id=xv420pEC2qMC&pg=PA183. 
8. ^ "Iron: geological information". http://www.webelements.com/iron/geology.html. Retrieved 2008-05-21. .
9. ^ Dauphas, N. & Rouxel, O. (2006). "Mass spectrometry and natural variations of iron isotopes". Mass Spectrometry Reviews 25: 515–550. doi:10.1002/mas.20078. http://geosci.uchicago.edu/~dauphas/OLwebsite/PDFfiles/Dauphas_Rouxel_MSR06.pdf. 
10. ^ The origins of Iron Working in India: New evidence from the Central Ganga plain and the Eastern Vindhyas by Rakesh Tewari (Director, U.P. State Archaeological Department)
11. ^ E. Photos (1989). "The Question of Meteoritic versus Smelted Nickel-Rich Iron: Archaeological Evidence and Experimental Results". World Archaeology 20 (3): 403–421. 
12. ^ Muhly, James D. 'Metalworking/Mining in the Levant' pp. 174-83 in Near Eastern Archaeology ed. S. Richard Winona Lake, IN: Eisenbrauns (2003): 180.
13. ^ Donald B. Wagner (2003). "Chinese blast furnaces from the 10th to the 14th century". Historical Metallurgy 37 (1): 25–37.  originally published in Donald B. Wagner (2001). "Chinese blast furnaces from the 10th to the 14th century". West Asian Science, Technology, and Medicine 18: 41–74. 
14. ^ ^{a b} Camp, James McIntyre; Francis, Charles Blaine (1920). The Making, Shaping and Treating of Steel. Pittsburgh: Carnegie Steel Company. pp. 173–174. http://books.google.com/books?id=P9MxAAAAMAAJ. 
15. ^ "Classification of Carbon and Low-Alloy Steels". http://www.key-to-steel.com/Articles/Art62.htm. Retrieved 2008-01-05. 
16. ^ Solid rocket boosters
17. ^ Vivian Marx (2002). "The Little Plankton That Could…Maybe". Scientific American. http://www.sciam.com/article.cfm?articleID=000A5750-8AC2-1D9C-815A809EC5880000. 
18. ^ Melinda Ferguson, David Labiak, Andrew Madden, Joseph Peltier. "The Effect of Iron on Plankton Use of CO2". CEM 181H. http://www.cem.msu.edu/~cem181h/projects/96/iron/cem.html. Retrieved 2007-05-05. 
19. ^ Dopyera, Caroline (October 1996). "The Iron Hypothesis". EARTH. http://www.palomar.edu/oceanography/iron.htm. Retrieved 2007-05-05. 
20. ^ Fox, B. A.; Threlfall, T. L. (1973), Org. Synth. 5: 346 
    Fox, B. A.; Threlfall, T. L. (1964), Org. Synth. 44: 34  Article
21. ^ Blomquist, A. T.; Dinguid, L. I. (1947). "Benzothiazoles. II. Nuclear chlorination in the Herz process". J. Org. Chem. 12: 718. doi:10.1021/jo01169a005. 
22. ^ Clarke, H. T.; Dreger, E. E. (1941), Org. Synth. 1: 304 
    Clarke, H. T.; Dreger, E. E. (1926), Org. Synth. 6: 52  Article
23. ^ den Hertog, J.; Overhoff (1950). Recl. Trav. Chim. 69: 468. 
24. ^ Nanami, M. et al. (2005). "Tumor necrosis factor-α-induced iron sequestration and oxidative stress in human endothelial cells". Arteriosclerosis, thrombosis, and vascular biology 25 (12): 2495–2501. doi:10.1161/01.ATV.0000190610.63878.20. http://cat.inist.fr/?aModele=afficheN&cpsidt=17328512. 
25. ^ Rouault, Tracey A. (2003). "How Mammals Acquire and Distribute Iron Needed for Oxygen-Based Metabolism". PLoS Biology 1: e9. doi:10.1371/journal.pbio.0000079. 
26. ^ Food Standards Agency - Eat well, be well - Iron deficiency
27. ^ Sesink AL, Termont DS, Kleibeuker JH, Van der Meer R (1999). "Red meat and colon cancer: the cytotoxic and hyperproliferative effects of dietary heme". Cancer Research 59 (22): 5704. PMID 10582688. 
28. ^ Glei M, Klenow S, Sauer J, Wegewitz U, Richter K, Pool-Zobel BL (2006). "Hemoglobin and hemin induce DNA damage in human colon tumor cells HT29 clone 19A and in primary human colonocytes". Mutat. Res. 594 (1-2): 162–71. doi:10.1016/j.mrfmmm.2005.08.006. PMID 16226281. 
29. ^ Pineda O, Ashmead HD (2001). "Effectiveness of treatment of iron-deficiency anemia in infants and young children with ferrous bis-glycinate chelate". Nutrition 17 (5): 381–4. doi:10.1016/S0899-9007(01)00519-6. PMID 11377130. 
30. ^ Ashmead, H. DeWayne (1989). Conversations on Chelation and Mineral Nutrition. Keats Publishing. ISBN 0-87983-501-X. 
31. ^ "Dietary Reference Intakes: Elements" (PDF). The National Academies. 2001. http://www.iom.edu/Object.File/Master/7/294/0.pdf. Retrieved 2008-05-21. 
32. ^ "Iron Deficiency Anemia" (web page). MediResource. http://bodyandhealth.canada.com/condition_info_details.asp?disease_id=274. Retrieved 2008-12-17. 
33. ^ Kumar, Vinay; Abbas, Abul K; Fausto, Nelson (2005). "Anemia". Robbins and Cotran: Pathologic Basis of Disease, 7th edition. Elsevier Saunders. http://www.mdconsult.com/das/book/body/90234262-4/0/1249/121.html. Retrieved 2008-03-14. 
34. ^ Durupt S, Durieu I, Nove-Josserand R, et al. (2000). "Hereditary hemochromatosis". Rev Med Interne 21 (11): 961–71. doi:10.1016/S0248-8663(00)00252-6. 
35. ^ Brar S, Henderson D, Schenck J, Zimmerman EA. (2009). Iron accumulation in the substantia nigra of patients with Alzheimer disease and parkinsonism. Arch Neurol. 66(3):371-4. PMID 19273756
36. ^ ^{a b} Cheney K, Gumbiner C, Benson B, Tenenbein M (1995). "Survival after a severe iron poisoning treated with intermittent infusions of deferoxamine". J Toxicol Clin Toxicol 33 (1): 61-6. doi:10.3109/15563659509020217. PMID 7837315. 
37. ^ ^{a b} "Toxicity, Iron". Emedicine. http://www.emedicine.com/emerg/topic285.htm. Retrieved 2006-06-19. 
38. ^ Tenenbein M (1996). "Benefits of parenteral deferoxamine for acute iron poisoning". J Toxicol Clin Toxicol 34 (5): 485-9. doi:10.3109/15563659609028005. PMID 8800185. 

Books

• Doulias PT, Christoforidis S, Brunk UT, Galaris D. Endosomal and lysosomal effects of desferrioxamine: protection of HeLa cells from hydrogen peroxide-induced DNA damage and induction of cell-cycle arrest. Free Radic Biol Med. 2003;35:719-28.
• H. R. Schubert, History of the British Iron and Steel Industry ... to 1775 AD (Routledge, London, 1957)
• R. F. Tylecote, History of Metallurgy (Institute of Materials, London 1992).
• R. F. Tylecote, 'Iron in the Industrial Revolution' in J. Day and R. F. Tylecote, The Industrial Revolution in Metals (Institute of Materials 1991), 200-60.

External links

Look up iron in Wiktionary, the free dictionary.

Wikimedia Commons has media related to: Iron

• WebElements.com – Iron
• It's Elemental – Iron
• The Most Tightly Bound Nuclei
• Crystal structure of iron
• Chemistry in its element podcast (MP3) from the Royal Society of Chemistry's Chemistry World: Iron

v • d • e Periodic table
H																															He
Li	Be																									B	C	N	O	F	Ne
Na	Mg																									Al	Si	P	S	Cl	Ar
K	Ca	Sc															Ti	V	Cr	Mn	Fe	Co	Ni	Cu	Zn	Ga	Ge	As	Se	Br	Kr
Rb	Sr	Y															Zr	Nb	Mo	Tc	Ru	Rh	Pd	Ag	Cd	In	Sn	Sb	Te	I	Xe
Cs	Ba	La	Ce	Pr	Nd	Pm	Sm	Eu	Gd	Tb	Dy	Ho	Er	Tm	Yb	Lu	Hf	Ta	W	Re	Os	Ir	Pt	Au	Hg	Tl	Pb	Bi	Po	At	Rn
Fr	Ra	Ac	Th	Pa	U	Np	Pu	Am	Cm	Bk	Cf	Es	Fm	Md	No	Lr	Rf	Db	Sg	Bh	Hs	Mt	Ds	Rg	Uub	Uut	Uuq	Uup	Uuh	Uus	Uuo
Alkali metals Alkaline earth metals Lanthanoids Actinoids Transition metals Other metals Metalloids Other nonmetals Halogens Noble gases

v • d • e   Iron compounds FeBr2 · FeBr3 · FeCl2 · FeCl3 · FeF2 · FeF3 · Fe(NO3)3 · FeO · FeO(OH) · Fe(OH)2 · FePO4 · FeS · FeSO4 · Fe2(CrO4)3 · Fe2O3 · Fe2(SO4)3 · Fe3O4 · Fe3(PO4)2

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - jern, kraft, styrke, strygejern, pistol
v. tr. - stryge, beklæde/beslå med jern
v. intr. - stryge
adj. - af jern, jern-, ubarmhjertig, hård

idioms:

• in irons    i lænker
• Iron Age    Jernalder
• iron curtain    jerntæppe
• iron discipline    hård disciplin
• iron hand    jernhånd
• iron horse    jernhest
• iron lung    jernlunge
• iron man    iron man, hel triatlon
• iron out    glatte ud, bringe ud af verden
• iron rations    nødration
• irons in the fire    jern i ilden

Nederlands (Dutch)
ijzer, steunbeugel, schietijzer, zilveren munten, strijkijzer, strijken, onbuigzaam, ijzeren, ijzersterk

Français (French)
n. - fer, fer à repasser, fer (au golf), attelle, (Méd) fer
v. tr. - repasser
v. intr. - repasser, se repasser (un vêtement)
adj. - de fer, en fer, draconien

idioms:

• in irons    aux fers
• Iron Age    âge de fer
• iron curtain    rideau de fer
• iron discipline    discipline de fer
• iron hand    (fig) poigne de fer
• iron horse    (US, Hist) locomotive à vapeur
• iron lung    poumon d'acier
• iron man    homme d'acier
• iron out    (lit) faire partir (qch) au fer, (fig) aplanir (un problème), peaufiner
• iron rations    vivres de réserve, vivres/rations, vivre sur ses rations
• irons in the fire    (avoir) beaucoup d'affaires en train

Deutsch (German)
n. - Eisen, Bügeleisen, Hand-/Fußschellen
v. - bügeln
adj. - eisern, stählern

idioms:

• in irons    in Eisen
• Iron Age    Eisenzeit
• iron curtain    eiserner Vorhang
• iron discipline    eiserne Disziplin
• iron hand    eiserne Faust
• iron horse    Dampfroß (Lokomotive)
• iron lung    eiserne Lunge
• iron man    stahlharter Mann
• iron out    herausbügeln, ausgleichen, beseitigen
• iron rations    eiserne Ration
• irons in the fire    mehrere Eisen im Feuer

Ελληνική (Greek)
n. - σίδερο, σίδηρος, σίδερο σιδερώματος, είδος μπαστουνιού του γκολφ, (καθομ.) σιδερικό, κουμπούρι
v. - σιδερώνω (ρούχα κ.λπ.)
adj. - σιδηρούς, σιδερένιος

idioms:

• in irons    στα σίδερα, σιδηροδέσμιος
• Iron Age    Εποχή του Σιδήρου
• iron curtain    το Σιδηρούν Παραπέτασμα
• iron discipline    αυστηρή/σιδηρά πειθαρχία
• iron hand    σιδερένια πυγμή
• iron horse    ατμομηχανή
• iron lung    (ιατρ.) τεχνητός πνεύμονας
• iron man    δυνατός αθλητής, τρίαθλο
• iron out    εξομαλύνω, ομαλοποιώ
• iron rations    (στρατ.) ξηρά τροφή
• irons in the fire    πολλές δουλειές ταυτόχρονα

Italiano (Italian)
ferri, stirare, ferro, ferro da stiro, di ferro

idioms:

• in irons    in catene
• Iron Age    età del ferro
• iron curtain    cortina di ferro
• iron discipline    disciplina di ferro
• iron hand    pugno di ferro
• iron horse    locomotiva
• iron lung    polmone d'acciaio, contenitore per spillare la birra (irlandese)
• iron man    uomo di ferro
• iron out    appianare
• iron rations    razioni di riserva
• irons in the fire    carne al fuoco

Português (Portuguese)
n. - ferro (m) (de passar roupa), ferro (m) (Quím.)
v. - passar a ferro, resolver (coloq.)
adj. - férreo

idioms:

• in irons    sem poder manobrar (barco a vela)
• Iron Age    idade (f) do ferro
• iron curtain    cortina (f) de ferro
• iron discipline    disciplina (f) férrea
• iron hand    mão firme
• iron horse    locomotiva (f)
• iron lung    pulmão (m) de aço
• iron man    homem (m) firme
• iron out    resolver as diferenças
• iron rations    ração (f) de reserva (enlatados)
• irons in the fire    dispor de muitos recursos ou estar envolvido em muitas tarefas ao mesmo tempo

Русский (Russian)
железо, железное изделие, утюг, оковы, оружие, железный, сильный, жестокий, злой, утюжить, покрывать железом, заковывать

idioms:

• in irons    в кандалах, связанный по рукам и ногам, плыть против ветра
• Iron Age    Железный век
• iron curtain    железный занавес
• iron discipline    железная дисциплина
• iron hand    железная рука
• iron horse    стальной конь (паровоз), мотоцикл
• iron lung    искусственные легкие
• iron man    серебряный доллар, врубовая машина
• iron out    выравнивать, устранять
• iron rations    неприкосновенный запас
• irons in the fire    несколько дел одновременно, различные средства

Español (Spanish)
n. - hierros, grilletes, grillos, hierro, acero, plancha
v. tr. - herrar, planchar, aherrojar
v. intr. - herrar, planchar
adj. - de hierro, férreo

idioms:

• in irons    encadenado, engrillado
• Iron Age    Edad del Hierro
• iron curtain    cortina de hierro
• iron discipline    disciplina férrea
• iron hand    mano de hierro
• iron horse    locomotora
• iron lung    pulmón de acero
• iron man    dólar, dólar de plata, hombre de hierro (musculoso), máquina que ejecuta un trabajo que antes se hacía a mano
• iron out    allanar dificultades, hacer desaparecer, suprimir, planchar
• iron rations    ración de reserva, raciones de campaña
• irons in the fire    tener muchas actividades, tener muchos recursos

Svenska (Swedish)
n. - järn (äv. bildl.), strykjärn, brännjärn, järnklubba (golf), järnpreparat (med.), järn (skjutvapen)
v. - stryka, slå i järn (bojor), fjättra, järnbeslå, gå att stryka
adj. - järn-, järngrå, järnhård, obarmhärtig

中文（简体）(Chinese (Simplified))
铁, 坚强, 熨斗, 用铁铸成, 熨, 烫平, 用铁包, 烫衣服, 铁的, 残酷的, 刚强的

idioms:

• in irons    被监禁
• Iron Age    铁器时代
• iron curtain    铁幕
• iron discipline    铁的纪律
• iron hand    铁腕, 坚强严厉的手段
• iron horse    火车
• iron lung    人工呼吸器
• iron man    铁人
• iron out    烫平, 消除
• iron rations    军用干粮, 野战应急口粮
• irons in the fire    手头上同时做各种工作

中文（繁體）(Chinese (Traditional))
n. - 鐵, 堅強, 熨斗
v. tr. - 用鐵鑄成, 熨, 燙平, 用鐵包
v. intr. - 燙衣服
adj. - 鐵的, 殘酷的, 剛強的

idioms:

• in irons    被監禁
• Iron Age    鐵器時代
• iron curtain    鐵幕
• iron discipline    鐵的紀律
• iron hand    鐵腕, 堅強嚴厲的手段
• iron horse    火車
• iron lung    人工呼吸器
• iron man    鐵人
• iron out    燙平, 消除
• iron rations    軍用乾糧, 野戰應急口糧
• irons in the fire    手頭上同時做各種工作

한국어 (Korean)
n. - 철, 다리미, 수갑
v. tr. - 다림질 하다, 수갑을 채우다, 철을 입히다
v. intr. - 다림질 하다
adj. - 철의, 굳은, 냉혹한

idioms:

• in irons    수갑을 차고, 잡힌 몸이 되어
• iron out    다림질 하여 펴다, 해소하다, 변동을 억제하다

日本語 (Japanese)
n. - 鉄, アイロン, 鉄製品, アイアン, 手かせ, 強さ
adj. - 鉄の
v. - アイロンをかける, アイロンがけをする

idioms:

• in irons    足かせをはめられて, 操船不能になって
• Iron Age    鉄器時代, 黒鉄時代
• iron curtain    鉄のカーテン, 共産圏の
• iron discipline    鉄の訓練
• iron fist    鉄拳
• iron hand    アイアンハンド
• iron horse    機関車, 戦車
• iron lung    鉄の肺
• iron man    1ドル銀貨, ドル, 粘り強くやりぬく男, 鉄人
• iron out    アイロンをかける, アイロンで伸ばす, 解決する, 取り除く
• iron rations    非常食
• soldering iron    はんだごて

العربيه (Arabic)
‏(الاسم) حديد, أصفاد, مكواة (فعل) يزود أو يكسو بالحديد, يكوي (صفه) حديدي‏

עברית (Hebrew)
n. - ‮ברזל, מגהץ‬
v. tr. - ‮גיהץ, ציפה בברזל, כבל באזיקים‬
v. intr. - ‮התגהץ‬
adj. - ‮עשוי מברזל, בלתי-נכנע, שלשלאות, כבלים, נחושתיים, ארכוף (לרגלי נכה)‬

If you are unable to view some languages clearly, click here.

To select your translation preferences click here.