Occurrence

Iron is, together with nickel, probably the main component of the earth’s core. Presumably driven by thermal forces, convection flows of liquid iron in the outer core produce the earth’s magnetic field . With a share of 4.7 percent, however, iron is also one of the most common elements of the earth’s crust. The first deposits that were mined were Rasiron and open ores. Today 40% of the iron ore is removed. The most important mineral for the production of iron is hematite, which consists largely of Fe 2 O 3. The largest iron ore deposits are found in the so-called Banded Iron Formations (BIF, banded iron ore or strip ore)

Iron is the 10th most common element in the universe. The fusion of elements in stars ends with the iron, since in the fusion of higher elements energy is no longer free, but must be expended. Heavier elements arise endothermically in supernova explosions, which are also responsible for the scattering of matter arising in the star.

Iron as a mineral

Very rarely, iron can also occur very well. The mineral crystallizes in the cubic crystal system, has a hardness of 4.5 and a steel gray to black color. Also the line color is gray.

Because of the reaction with water and oxygen (rusting), solid iron is not stable. It therefore occurs in alloy with nickel only in iron meteorites, as well as in basaltes , where iron- containing minerals are sometimes reduced. Iron ore is found, however relatively common, important examples are magnetite (Fe 3 O 4), hematite, hematite (Fe 2 O 3), limonite (Fe 2 O 3 · n H 2 O).

Story

Middle East

Iron was used by humans for the first time around 4000 BC in Sumer and Egypt. It was a solid iron of meteorites, used to decorate spears.

Between 3000 and 2000 BC, iron found in Mesopotamia, Anatolia, and Egypt (distinguishable from the meteorite by the absence of nickel). It seems to have been used only ceremonial and was more precious than gold. It may have been in the form of sponges as a by-product of bronze production.

Between 1600 and 1200 BC iron was increasingly used; The Hittites probably knew a method for the economic production of iron. However, it did not solve bronze . During this time it remained largely monopoly of the Hittite Empire (in the area of ​​today’s Turkey) and was a factor of its rise. From 1200 BC the transition from the Bronze Age to the Iron Age took place with the fall of the Hittite Empire and the dissemination of knowledge in the Middle East. It is assumed that not only the material superiority of the iron but a lack of tin (necessary for the bronze production) triggered the transition. However, the superiority of iron armor and weapons against bronze weapons can also be an important reason.

During the first ice-age smelting process, sponges formed. By the use of charcoal in the further processing carbon was added to the iron, with the final result of a (at least superficial) steel. By careful curing (i.e. careful and skillful cooling, generally in a liquid such as water or oil), workpieces with a hitherto unknown elasticity and hardness which were far superior to bronze were produced.

China

Also in China, the first experiences with iron were obtained from meteorite iron. First archaeological traces of wrought iron are found in the north-west, near Xinjiang, from the 8th century BC. It is assumed that these products, which were created with the methods of the Middle East, have reached China through trade.

In 550 BC, the blast furnace was developed: now it was possible to produce cast iron .

Europe

In addition to its outstanding importance as a material, iron was used in alchemy , where it was associated with the sign for Mars / masculinity.

Since European processing techniques ( racing kilns ) only reached temperatures of almost 1,300 ° C, the development of cast iron took place in the 15th century in Sweden (Lapphyttan and Vinarhyttan). With the cast cannon ball, cast iron processing spread rapidly as the campaigns spread across Europe.

When the dwindling forests were no longer able to cover the growing charcoal requirements for iron production in the UK, coal (the coal product of coke) was developed by Abraham Darby as an alternative. This conversion, together with the invention of the steam engine, is considered the beginning of the industrial revolution.

Iron findings

Iron finds are compared with the finds of bronze relatively rare, partly because the iron was used in the earliest periods only to a small extent to the other because of the great tendency of iron in moist air, in the water and in the wet earth corrode , causing the objects Could not get. Only special circumstances or large proportions of the object prevented the loss of such pieces.

One of the oldest finds is from the Cheopspyramide and was found in 1837 by JR Hill in the loss of some stone layers in a wall gap, where it was protected from rust. It is the fragment of a larger wrought iron tool and has an age of about 5,000 years. A later find is the piece discovered by Belzoni under a Sphinx in Karnak, which was recognized as part of a sickle and is about 2,800 years old.

In Asia, iron items were found in the tombs of Turan and larger iron warehouses in the ruins of Khorsabad, where rings and chains were discovered along with about 160,000 kg of iron bars. Layard also encountered iron weapons such as helmets, spears, and daggers during his excavations in Nimrud. The famous pillar of Delhi in the Qutb complex is a 7 m high wrought-iron massive column about half a meter in diameter, which since the beginning of the fifth century has been revered by the Indians as sacred and contains Sanskrit inscriptions.

Among the oldest European pieces are the iron tents and spears that Count Gozzadini discovered in Etruscan tombs near Bologna in 1853. They date from the 9th to 10th century BC.

Production and representation

  Iron ore is extracted in opencast mining and civil engineering (underground construction). Where the deposits of iron ore recognized as degradable are open, the ore can be extracted in a less elaborate opencast mine. Today, iron ore is mined mainly in South America, especially in Brazil, in Western Australia, in the People’s Republic of China, in Eastern Europe (such as Ukraine) and Canada.

In the last few years, these countries have replaced the original iron ore countries, such as France, Sweden or Germany, whose last iron ore mine was closed in the Upper Palatinate in 1987

Huge ore mining areas such as the Ok Tedi mine in Papua New Guinea affect not only the rainforest but also the untreated discharge of sewage and sludge in rivers partly also the population that makes use of the river water. However, the number of people who earn their livelihood through the mine in the bitterest land and often owe their existence is much greater. Only rarely does the iron ore come directly from the mine to the storage facilities of the huts. In most cases, only long distances have to be traveled by land and by sea, with several transshipment.

Before further processing, the ore is finally crushed and milled. Then the ore grains are sorted and sintered according to their size. This means that small ore grains are placed together with lime aggregates on gas-fueled, motor-driven traveling grates (rust conveyor belt) and are “baked together” by strong heating, since only in this form as sintered coarse chunks is the use in the blast furnace possible, Or the air supply (wind) very much.

Only a small part of the ore can be used directly as a lump in the blast furnace. The main part of the iron ore is processed into fine sinter in a sintering plant. The ore is intensively mixed with limestone, fine-grained coke (coke grass) and water and is given up to a rusty rust. The grate is vacuumed from below. From above is ignited and a firing front travels from top to down through the mixture, which is briefly melted. A significant proportion of ore is processed into pellets. For this purpose, the ore is pulverized in a pulverulent manner, which is often already necessary for the separation of gait. With binders, additives and water, a mixture is produced, which is then rolled on pelletizers to beads of 10 to 16 mm diameter. These are burned on a hiking grate with gas firing to pellets. Sinter is not easily transportable and is therefore produced in the metallurgical plant. Pellet plants are mostly operated near the ore mines.

Blast furnace process

The iron is obtained by chemical reduction of the iron oxide of the iron ores with carbon in the blast furnace. The blast furnace is a chess furnace. Coke and ore are alternately poured into layers at the top of the furnace. For this purpose, two bunkers are usually arranged above the furnace vessel and serve as gas sluices between the furnace vessel and the environment. At the top, inside the furnace vessel, there is a rotary chute with which the material is distributed helically over the feed surface. When the ore becomes plastic, the coke layers maintain the permeability of the filling with process gas (coke window) in the lower region of the furnace.

The insert sinks in the furnace shaft and is thereby dried, heated, reduced and finally melted (redox reaction) by the ascending process gas . The entire process takes about eight hours. The process gas is produced by blowing air preheated to about 1200 ° C. down into the furnace by water-cooled copper nozzles (blow molding). The oxygen of the air burns with coke to form carbon monoxide, whereby the process gas, which consists of carbon monoxide and nitrogen, which is about 2000 ° C. hot, reduces the iron oxides. The exhaust gas remaining therefrom, obtained at the upper end of the furnace well, is combustible and is used for preheating the air. Excess gas is used to generate electricity in a power plant.

The furnace produces liquid slag next to the liquid iron. Both are peeled off at a temperature of about 1450 ° C. by means of a tapping hole, which is opened approximately every two hours by tapping and is closed by a ceramic mass after about one hour each time by clogging. Iron and slag are separated outside the furnace. The iron is filled into transport pans and transported to the steelworks. The iron is liquid at 1450 ° C, as by the dissolved carbon in the iron, a melting point depression is performed. The slag is evaporated with water. It solidifies as a fine-grained glass (slag sand) by quenching. This slag sand is finely ground and used as cement. A blast furnace produces about 200 to 300 kg of slag per ton of iron.

Ore and coke contain silica (silica sand, silicates) SiO 2 and alumina Al 2 O 3 as the main contaminant . A small portion of the silicon dioxide is reduced to silicon, which is dissolved in the iron. The rest forms together with the alumina the slag (aluminum silicates).

Since the melting point of a mixture of SiO 2 and Al 2 O 3 is too high to form a slag which is liquid at 1450 ° C., calcium oxide (calcined lime, CaO) is used for the melting point reduction. This is usually already added as limestone during the production of the iron ore sinter.

The iron of the furnace (pig iron) has only an iron content of about 95%. It contains for most applications too much carbon, sulfur, silicon and phosphorus. Therefore, in the steelworks, a reduction in the amount of calcium carbide, magnesium or burnt lime is first desulphurized. The desulfurization slag is removed and then the pig iron in a converter (oxygen blowing) under addition of quicklime oxidizing blown. In this case, silicon to silicon dioxide and carbon to carbon dioxide burned. The phosphorus is used as calcium phosphate bound. The liquid iron thereafter has a temperature of about 1600 ° C. It contains enough oxygen to form carbon monoxide bubbles when solidified from remaining carbon. This is undesirable in the case of the most commonly used continuous casting today. Therefore, when tapping the steel from the converter into the ladle is aluminum added to adjust the oxygen as alumina to bind. In the case of high demands on the quality of the steel, further process steps, such as, for example, a vacuum treatment ( secondary metallurgy ), are followed by the converter process. The liquid iron thereafter has a temperature of about 1600 ° C. It contains enough oxygen to form carbon monoxide bubbles when solidified from remaining carbon. This is undesirable in the case of the most commonly used continuous casting today. Therefore, when tapping the steel from the converter into the ladle is aluminum added to adjust the oxygen as alumina to bind. In the case of high demands on the quality of the steel, further process steps, such as, for example, a vacuum treatment ( secondary metallurgy ), are followed by the converter process. The liquid iron thereafter has a temperature of about 1600 ° C. It contains enough oxygen to form carbon monoxide bubbles when solidified from remaining carbon. This is undesirable in the case of the most commonly used continuous casting today. Therefore, when tapping the steel from the converter into the ladle is aluminum added to adjust the oxygen as alumina to bind. In the case of high demands on the quality of the steel, further process steps, such as, for example, a vacuum treatment ( secondary metallurgy ), are followed by the converter process. Carbon monoxide bubbles are formed during solidification from remaining carbon. This is undesirable in the case of the most commonly used continuous casting today. Therefore, when tapping the steel from the converter into the ladle is aluminum added to adjust the oxygen as alumina to bind. In the case of high demands on the quality of the steel, further process steps, such as, for example, a vacuum treatment ( secondary metallurgy ), are followed by the converter process. Carbon monoxide bubbles are formed during solidification from remaining carbon. This is undesirable in the case of the most commonly used continuous casting today. Therefore, when tapping the steel from the converter into the ladle is aluminum added to adjust the oxygen as alumina to bind. In the case of high demands on the quality of the steel, further process steps, such as, for example, a vacuum treatment ( secondary metallurgy ), are followed by the converter process. In the case of high demands on the quality of the steel, further process steps, such as, for example, a vacuum treatment ( secondary metallurgy ), are followed by the converter process. To bind the oxygen as alumina . In the case of high demands on the quality of the steel, further process steps, such as, for example, a vacuum treatment ( secondary metallurgy ), are followed by the converter process.

Characteristics

The average iron atom has about 56 times the mass of a hydrogen atom. The atomic nucleus of the iron isotope 56Fe has one of the largest mass defects and thus one of the highest binding energies per nucleon of all atomic nuclei. For this reason, it is regarded as a final stage in the generation of energy by nuclear fusion in the stars.

At room temperature the allotropic modification of pure iron is ferrite or α-iron. This modification has a cubic space-centered crystal lattice , which is below 911 ° C. Below the Curie point at 766 ° C the ferrite is ferromagnetic . The modification between 766 ° C and 911 ° C is called β-iron. Since, apart from the magnetic properties, it does not differ from the ferrite α-iron, it is usually also referred to as α-iron.

To 1392 ° C, it is the face-centered cubic γ-modification or austenite before. As the temperature continues to rise, the iron transforms into δ-ferrite, which again has a cubic, space-centered lattice. The melting point is 1535 ° C.

This characteristic of the conversion of the lattice from cubic-space-centered (up to 911 ° C) over cubic-surface-centered (up to 1392 ° C) to cubic-centered (up to 1539 ° C) as well as the subsequent decay of the lattice structures is also called the ” polymorphism of the iron “.

Iron is resistant to dry air, dry chlorine, concentrated sulfuric acid, concentrated nitric acid and basic agents (except hot sodium hydroxide solution) with a pH of more than 9.

Isotopes

Iron has four naturally occurring, stable isotopes, with the relative abundances: 54 Fe (5.8%), 56 Fe (91.7%), 57 Fe (2.2%) and 58 Fe (0.3%). The isotope 60 Fe has a half-life of 1.5 million years. The existence of 60 Fe at the beginning of the formation of the planetary system was demonstrated by the correlation between the frequencies of 60 Ni , the decay product of 60 Fe, and the frequencies of the stable Fe isotopes in some phases of some meteorites (for example in the meteorites Semarkona and Chervony Kut ) can be detected. Possibly, the released energy played a role in the melting and differentiation of the asteroids immediately after their formation about 4.6 billion years ago in the radioactive decay of 60 Fe, in addition to the atomic decay energy of the radioactive 26 Al, which is also present. Today, nearly all of the original 60 Fe was decomposed completely into 60 Ni. The distribution of nickel and iron isotopes in meteorites makes it possible to measure the isotope and element frequency in the formation of the solar system and to open up the prevailing conditions before and during the formation of the solar system. In addition to the atomic decay energy of the radioactive 26 Al , which is also present, plays a role in the melting and differentiation of the asteroids immediately after their formation about 4.6 billion years ago. Today, nearly all of the original 60 Fe was decomposed completely into 60 Ni. The distribution of nickel and iron isotopes in meteorites makes it possible to measure the isotope and element frequency in the formation of the solar system and to open up the prevailing conditions before and during the formation of the solar system. In addition to the atomic decay energy of the radioactive 26 Al , which is also present, plays a role in the melting and differentiation of the asteroids immediately after their formation about 4.6 billion years ago. Today, nearly all of the original 60 Fe was decomposed completely into 60 Ni. The distribution of nickel and iron isotopes in meteorites makes it possible to measure the isotope and element frequency in the formation of the solar system and to open up the prevailing conditions before and during the formation of the solar system. 6 billion years. Today, nearly all of the original 60 Fe was decomposed completely into 60 Ni. The distribution of nickel and iron isotopes in meteorites makes it possible to measure the isotope and element frequency in the formation of the solar system and to open up the prevailing conditions before and during the formation of the solar system. 6 billion years. Today, nearly all of the original 60 Fe was decomposed completely into 60 Ni. The distribution of nickel and iron isotopes in meteorites makes it possible to measure the isotope and element frequency in the formation of the solar system and to open up the prevailing conditions before and during the formation of the solar system.

Only the iron isotope 57 Fe has a nuclear spin.

Use

  Iron is technically very important for the production of steel. Steels are alloys of iron that are formed during mixing (alloying) with other metals and also non-metals (especially carbon ). Iron is the most widely used in the world with 95 percent of the metal used. The reason for this is its wide availability, which makes it quite inexpensive, as well as the excellent strength and toughness achieved with the incorporation of alloys with other metals such as chromium, molybdenum and nickel, which makes it a basic material for many areas in the art. It is used in the production of land vehicles, ships and the entire construction sector (reinforced concrete).

Iron (besides cobalt and nickel) is one of those three ferromagnetic metals which, by virtue of their property, enable the large-scale use of electromagnetism in generators, transformers, chokes, relays and electric motors. It is alloyed pure or, among other things, with silicon , aluminum, cobalt or nickel (see Mu metal ) and serves as soft magnetic core material for guiding magnetic fields, shielding magnetic fields or increasing the inductance. It is produced massively, in the form of sheets or powder (powder cores).

Pure iron powder is also used in chemistry.

Various steels are widely used in industry; In Germany about 7.500 varieties are standardized. Iron is used in the following forms:

  • Pig ironcontains four to five percent carbon and varying amounts of sulfur, phosphorus and silicon. It is an intermediate in the production of cast iron and steel.
  • Cast ironcontains 2.06 to 6.67% carbon and other alloying elements such as silicon and manganese. Depending on the cooling rate, the carbon is found in the cast iron as a carbide or elementary as a graphite. According to the appearance of the fracture surfaces, the former is called white, and in the second case, gray cast iron. Cast iron is very hard and brittle. It can usually not be plastically deformed.
  • Steelcontains between 0.06% and 2.06% carbon. In contrast to cast iron, it is plastically deformable. By alloying, as well as by a suitable combination of thermal treatment and plastic forming (cold rolling), the mechanical properties of the steel can be varied within wide limits.
  • In the case of unalloyed steels with a carbon content of up to 0.8%, steel is referred to as structural steel, and over 0.8% of tool steel.

In medicine, iron-containing preparations are used as antianamines , causally in the treatment of iron deficiency anemia and additive in the treatment of anemia caused by other causes.

Smell of iron

  The typical smell, classified as metallic, when touching iron objects is a chemical reaction of substances of sweat and fat of the skin with divalent iron ions. [2]

One of the most important fragrance carriers is 1-octen-3-one, which still smells fungal-like metallic in large dilution. The precursors of the odorants are lipid peroxides. These arise when skin fat is oxidized by certain enzymes or other processes (eg UV-content of the light). These lipid peroxides are then decomposed by the divalent iron ions to form the fragrances. The divalent iron ions are formed by corrosion of the iron in contact with the hand weld, which contains corrosive organic acids and chlorides.

When rubbing blood on the skin, a similar smell is produced. Blood also contains iron ions.

Medical significance

Normal iron metabolism

Iron is an essential trace element for almost all living beings, especially for the formation of blood. It is oxidized in the body as iron (II) and iron (III). As the central atom of the cofactor heme in hemoglobin and myoglobin, it is responsible for oxygen transport and storage in many animals and humans. In these proteins it is surrounded by a planar porphyrin ring. Furthermore, iron is a component of iron-sulfur complexes (iron-sulfur cluster) in many enzymes , for example nitrogenases , hydrogenases or the complexes of the respiratory chain . The third important class of iron enzymes is the so-called non-heme iron enzymes, for example methane monooxygenase , ribonucleotide reductase and hämerythrin. These proteins are responsible for oxygen activation , oxygen transport, redox reactions and hydrolysis in various organisms . Equally important is trivalent iron as the central ion in the enzyme catalase, which degrades the metabolic toxin of hydrogen peroxide in the peroxisomes of the cells. These proteins are responsible for oxygen activation, oxygen transport, redox reactions and hydrolysis in various organisms . Equally important is trivalent iron as the central ion in the enzyme catalase, which degrades the metabolic toxin of hydrogen peroxide in the peroxisomes of the cells. These proteins are responsible for oxygen activation, oxygen transport, redox reactions and hydrolysis in various organisms . Equally important is trivalent iron as the central ion in the enzyme catalase , which degrades the metabolic toxin of hydrogen peroxide in the peroxisomes of the cells.

Iron and iron

Especially women often suffer from iron deficiency, the reason for this is menstruation – on each day the body loses about 15 milligrams, at the birth of a child about 1000 milligrams of iron. The daily requirement of an adult man is about 10 milligrams of iron. An adult woman (up to 51 years old) should supply approximately 15 milligrams of iron. By the simultaneous intake of vitamin C, the resorption rate is significantly increased. Particularly rich is iron contained in meat, liver, legumes and whole grain bread. The absorption of iron by food is inhibited by the simultaneous consumption of dairy products, coffee or black tea.

Toxicity and iron overload

Although iron is an important trace element for humans, too much iron can be toxic to the body , i.e. toxic . For large amounts of Fe 2+ – ions react with peroxides , where free radicals are formed. In the normal state, the latter are controlled by body-specific processes.

About one gram of iron causes serious poisoning symptoms in a two-year-old child, three grams can be fatal. In an adult man, from about 2.5 grams of iron (which is not bound to hemoglobin) in the blood serious poisoning phenomena occur. Long-term over-supply with iron leads to hemochromatosis , an iron storage disease. The iron accumulates in the liver and leads to siderosis (deposition of iron salts) and organ damage. Therefore, iron preparations are only recommended for iron deficiency. However, in the case of iron supply the body does not absorb this from the food. [3] Since iron is a transition metal, it can, especially in its divalent form (Fe 2+ ) Can also lead to neurodegenerative diseases such as Parkinson’s disease or Alzheimer’s disease due to an over-supply in the brain under certain conditions. [4]

Proof

In the detection reaction for iron ions, the two cations Fe 2+ and Fe 3+ are first distinguished.

Iron detection with thioglycolic acid

With thioglycolic to leave Fe 2+ – and Fe 3+ prove ions:

Fe 2+ + 2 HS-CH 2 -COOH → [Fe (SCH 2 COO) 2 ] 2- + 4H +

In the presence of Fe 2+ or Fe 3+ ions, an intense red coloration results.

Iron detection with hexacyanoferrates

The Fe 2+ ions can be detected with a red blood leaching salt:

3 Fe 2 + 2 K 3 [Fe (CN) 6 ] → Fe 3 [Fe (CN) 6 ] 2 + 6 K +

The product is called Turnbull’s Blue (which is basically the same as Berlin Blue). No complexing reaction takes place but only ion exchange ( precipitation reaction ).

Fe 3+ ions can be detected with yellow blood leaching salt:

4 Fe 3 + 3 K 4 [Fe (CN) 6 ] → Fe 4 [Fe (CN) 6 ] 3 + 12 K +

This detection reaction produces Berlin blue , an important dye.

The Fe 2+ or Fe 3+ ions can therefore be detected as soluble or insoluble Berlin / Turnbulls blue with the aid of potassium hexacyanoferrate (II / III). Berliner Blau and Turnbull’s blue are actually just two names for the same connection. This is easy to understand when you know that the blue color results from metal-metal batch transfer . Fe III turns into Fe II and vice versa. It is noteworthy that this known iron detection reagent itself contains iron, which is chemically well masked by the cyanide ions (innerorbital complex) and thus reveals the limitations of chemical analysis.

Iron detection with thiocyanates

Alternatively, iron (III) salts with thiocyanates (rhodanides) can be detected. This reacts with iron (III) ions to give iron (III) thiocyanate:

Fe 3+ + 3 SCN  → Fe (SCN) 3

The deep red Fe (SCN) 3 forms , which remains in solution. However, some of these entropies disrupt this detection (eg Co 2+ , Mo 3+ , Hg 2+ , excess of mineral acids ), so that a cation separation may have to be carried out.

links

Valences and oxidation states

  • Fe1+ , extremely unusual, eg as Fe [(H 2 O) 5 NO] 2+ . (Ring test, detection of NO  )
  • Fe2+ , these salts are mostly pale green,
  • Fe3+ , these ions are almost colorless. Solutions of Fe (III) salts are strongly acidic and yellow. The color is formed by charge-transfer bands of hydroxo ions, as in [Fe (H 2 O) 5 OH] 2+ .
  • Fe4+ occurs in the catalysis cycles of some enzymes (for example, cytochrome c oxidase , cytochrome P450 , peroxidases ),
  • Fe5+ , FeO 3-
  • Fe6+ is rare (for example K 2 FeO 4 ).

Oxides

Iron forms divalent and trivalent oxides with oxygen:

  • Iron (III) oxide(Fe 2 O 3 ) is a brown substance. It is formed by the oxidation of iron in the oxygen excess.
  • Iron (II) oxide(FeO) is produced by direct burning of iron, eg with the cutting torch. It is black and unstable to 560 ° C.
  • Iron (II, III) oxide(Fe 3 O 4 ) is produced by conversion of FeO.

Since these oxides do not form a solid protective layer, an iron body exposed to the atmosphere oxidises completely. When collected prior to final rusting and recycled, rusted iron and rusted steel are a coveted and valuable oxygen carrier for steel production in the electric melting furnace. This oxygen in the iron scrap acts as an oxidizing agent in “steel cooking” in order to oxidize (burn) unwanted quality-reducing impurities (eg light metals).

Salts

Iron forms divalent and trivalent salts:

  • Iron (II) chloride(FeCl 2 ) is used for sulphide precipitation , sludge desulphurization , biogas desulphurisation , chromate reduction and phosphate elimination; This includes simultaneous precipitation.
  • Iron (II) sulfate(FeSO 4 ) is alsocalled the green salt because of its color. Applications such as iron (II) chloride and dried iron (II) sulfate as a chromate reducer especially in the cement against the chromate energy.
  • Iron (III) chloride(FeCl 3 ) can oxidize and dissolve copper ; Therefore aqueous ferric chloride solutions can be used for gentle etching of printed circuit boards. Reaction formula:

Cu + 2 FeCl 3 = CuCl 2 + 2 FeCl 2

  • Iron (III) chloride sulfate (FeClSO4 )

All iron salts are used, inter alia, as flocculants and for the elimination of phosphate, including precipitation, simultaneous precipitation, post-precipitation and flake filtration as well as sulphide precipitation , sludge gas desulphurisation , biogas desulphurisation

Other iron compounds

Single iron compounds:

  • Fe3 C, iron carbide ,
  • Fe (CO)5 , iron carbonyl , iron pentacarbonyl, IPC (I for iron), is formed under pressure from iron and carbon monoxide and, after its decomposition, forms a particularly pure iron powder, the carbonyl iron, next to carbon monoxide. A further variant of iron carbonyl is Fe 2 (CO) 9 and Fe 3 (CO) 12 .
  • Fe (SCN)3 , iron (III) thiocyanate , iron rhodanide , has a very rich blood-red coloring and serves to detect Fe 3+