It is more or less generally known that the material commonly called iron, even in the simplest case, is an alloy of iron itself, as a chemical element, with carbon. When the carbon concentration is less than 0.3%, a soft, ductile, refractory metal is obtained, to which the name of its main ingredient is assigned - iron. An idea of the iron with which our ancestors dealt can now be obtained by examining mechanical properties nail.

With a carbon concentration of more than 0.3% but less than 2.14%, the alloy is called steel. In its original form, steel is similar in its properties to iron, but, unlike it, it can be hardened - upon rapid cooling, the steel acquires greater hardness - a remarkable advantage, however, almost completely negated by the fragility acquired during the same hardening process.

Finally, when the carbon concentration is above 2.14%, we get cast iron. A fragile, fusible metal, well suited for casting, but not amenable to forging.

One of the determining conditions for starting metal production is knowledge about the minerals containing this metal. These minerals must be noticeable and attract attention, both by their unique appearance and by some specific properties that ancient man could be used, including in archaic thermal processes. All iron minerals, which are discussed in detail below, have similar external data and properties in full.

The history of primitive human society was inextricably linked with stone and products made from it. The most primitive of these products were ordinary river pebbles, chipped at one edge. The age of the oldest stone tools dates back to a period of about 2.5 million years.

At first, our ancestors used any pebbles. However, as they explored new territories, they began to show interest in a wide variety of rocks. It is difficult to say when primitive man learned to distinguish between them, but it is known for certain that flint became his favorite stone throughout the entire Anthropocene. This predilection is due to the amazing properties of flint - its ability, during directed blows, not to split into pieces, but to produce thin flakes and plates with sharp edges. Having beaten the stone from different sides, the ancient man received a hand ax and many sharp flakes. Both were used: choppers were used for processing wood, flakes were used for cutting meat.

A lot of time passed before man learned to separate flakes from flint stones. This required the development of certain stone processing skills. By splitting the stone, the ancient master received one or several plates - an excellent material for making spearheads, scrapers and knife-like tools. It was in flint that the form of such famous tools as an ax, sickle, knife, and hammer was first found and embodied.

Jasper, a strong and very hard rock, obsidian and jade also had high consumer properties. However, these stones were and are found in nature much less frequently than flint.

2.2.1 Goethite (α-Fe) (hydrogoethite, limonite, brown ironstone)

This mineral got its name in honor of J.V. Goethe, a brilliant poet, and, in addition, an outstanding naturalist and expert on minerals. Probably, it was he, in all the diversity of its manifestations, that became the first ore from which people learned to extract iron.

Figure 10 – Goethite

On earth's surface iron in divalent form is slowly leached from rocks by soil and river waters containing plant humic acids. In meadows and other open places, in oxygen-saturated lake water, it is oxidized to trivalent and precipitated in the form of insoluble goethite, forming “lake”, “meadow” and “turf” ores. This is where another name for goethite comes from - limonite - from the Greek word “leimon”, which means “wet meadow” or “swamp” (Figures 11,12).

Strictly speaking, limonite is not a mineral, but a mixture of various minerals - iron hydroxides, of which goethite is the main one. Essentially limonite is “natural rust”, from where (for its characteristic rusty-brown color) its other name “brown iron ore” comes. It is in swamps, lakes and shallow seas that unusual-looking limonite ores occur (Figure 13). Limonite from such ores resembles beans or small bird eggs. Therefore, limonite names such as “bean ore” or “pea stone” are widely used. Goethite is also found in the form of loose ocher staining your hand, in the form of lacquered black clusters and buds, and cascades of icicles, and delicate velvet covers and pads in cracks and caves, and in the form of shiny fans and diamond-black or red needles and hairs in crystals amethyst - all are iron hydroxides, that is, all are goethite or hydrogoethite. In addition, goethite is common in the form of “glass heads” - beautiful spherulite crusts with a varnish-black surface.

Figure 11 - Mining of “lake” ores Figure 12 – Mining of “meadow” ores

Figure 13 – Swamp ore

2.2.2 Hematite (Fe 2 O 3)

Hematite is a mineral with a beautiful shape, sparkling edges, color from steel to iron-black, with a special reddish tint, which clearly distinguishes hematite from similar minerals (Figure 14). Modern name This mineral was first found in Theophrastus (a natural scientist and philosopher who lived in 372–287 BC and wrote the treatise “On Stones”). It comes from the Greek word “hema” - blood, which is associated with the cherry or wax-red color of the mineral powder, as well as the synonyms of hematite - “bloodstone”, “red ironstone”. Another ancient synonym for hematite is “iron shine.” Hematite crystals have high hardness and density, a strong semi-metallic luster, and a cherry-red color. Special shiny tabular-shaped crystals were previously called “specularite,” and thin-plate crystals, sometimes collected in parallel packages, were called “iron mica.”

Figure 14 - Hematite

Spherulitic hematite crusts are very common; in the old days, German miners called them “glass heads.” Much less common is another form of splitting hematite crystals - “iron rose”, where plate-like crystals are arranged like cards in an unfolded deck. “Iron roses” are valued on a par with the most expensive minerals.

Hematite is also found in dense masses, in peculiar powdery secretions (“iron sour cream”), and most of all in the form of granular inclusions in various rocks. It is released in significant quantities during volcanic processes. It is a known fact that in 1817, during the eruption of Vesuvius, a meter thick layer of hematite was formed in just 10 days. Dense hematite is an excellent mineral for carving various figures.

It is from hematite that the word “gemma” comes from, meaning carved stone. IN Ancient Egypt and Babylon, carved hematite was widely used as decoration, in Ancient Greece carved stones in their own way served as locks and keys. Everything that we are accustomed to locking, the Greeks sealed with a personal seal. To make such seals with in-depth images, hematite and chalcedony were most often used.

Another area of application of hematite was medicine. The famous physician of antiquity, Dioscurus, named hematite among the five main stones for healing (with amber, lapis lazuli, jade and malachite). Hematite was credited with the ability to heal bleeding wounds, heal bladder diseases and venereal diseases.

Fine crocus hematite powder was used in ancient times to polish gold and silver items. It should be noted that the abrasive properties of the mineral, unlike the medical ones, have not lost their importance to this day.

It is believed that the first purpose of hematite was its use in the form of mineral paint. The oldest discovery of hematite paints in human burials dates back to approximately 40 thousand years BC.

Red hematite paint - mummy - was an essential component of mummification among the ancient Egyptians (hence its name). Hematite amulets were placed in a strictly defined order between the bandages of the mummies of the pharaohs. Until the Middle Ages, the only yellow paint was ocher. It was made by mixing hematite with chalk. Later, yellow paint was made from a mixture of lead oxide and red lead.

Finally, amazing bloodstone crystals (“scorpion stone”) found special use in Medieval magic. Only if he had a ring with bloodstone on his finger could a medieval magician dare to call the spirits of the dead into communication.

2.2.3 Siderite (FeCO 3)

Another contender for the title of the first iron ore mineral in human history is siderite. Its natural manifestations are perhaps the least spectacular among other iron ores. They are usually buds, nodules or oolitic (spherical) textures of numerous brownish-yellow shades (Figure 15).

Figure 15 – Siderite

The name of the mineral comes from the Greek word “sideros” - iron (which, in turn, also means a star, i.e. iron is a star metal - a metal that comes from the sky). There is another version of the origin of the word “sideros”, which has become widespread in recent decades. According to this version, the Greek "sideros" is of Caucasian origin from the root "sido", which means "red". An important circumstance confirming this version is the generally accepted fact that the birthplace of ore iron is Asia Minor, from where, through the legendary people of blacksmiths - the Calibers, the ancient Greeks learned about iron. This is also where another name for the mineral comes from – halibite. Other common names: girite, flintz, iron spar, white ore. Especially great importance siderite ores played a role in the development of iron metallurgy in the early Middle Ages, when the Alpine region became the main center of its production. It is in the Alps that there are famous siderite deposits: Neudorf and Eruberg, as well as the famous “mountain” – Eisenerz.

2.2.4 Pyrite and marcasite (FeS 2)

The name “pyrite” comes from the Greek word “pyros” - fire, fire-like.

A blow to it produces sparks, which is why in ancient times pieces of pyrite served as an ideal stone. The mineral received its second name “pyrite” in the 16th century. – it was assigned to pyrite by the outstanding German scientist Agricola (Georg Bauer) and also has Greek roots, since it comes from the name of the Greek peninsula of Halkidiki, rich in various ores. Subsequently, the name “pyrites” extended to the entire class of sulfides similar to pyrite, and pyrite itself began to be called iron or sulfur pyrites.

The yellow color of pyrite is sometimes masked by brown or mottled tarnish, because it often contains impurities of arsenic, cobalt, nickel, and less often copper, gold, and silver. The most characteristic thing in the appearance of a mineral is the shape of its crystals - most often it is a cube (Figure 16). The largest known pyrite crystal, measuring 50 cm along the edge, was found near the city of Xanthi in Northeastern Greece. IN Ancient India Pyrite crystals served as an amulet that protected against crocodiles.

Figure 16 – Pyrite

In nature, pyrite is widespread and very noticeable. It literally catches your eye with its golden color, bright shine of almost always clean edges, and clear crystalline forms. For these reasons, pyrite has been known since ancient times. In color and shine, it resembles brass, and even gold, for which it once earned the condescending nickname “cat’s gold.” Polished pyrite shines even brighter. The ancient Incas made mirrors from polished pyrite. The oldest known deposits of pyrite are Rio Tinto and Novokhun (Spanish Pyrenees), Rio Marina (Elba Island), and the Ural Mountains.

An amazing property of pyrite is its replacement by crystals in the reducing environment of organic remains. In this case, spectacular fossils are formed: pyritized shells, pieces of wood and even whole fragments of trunks and other parts of plants, etc. The replacement process can proceed very vigorously: in the famous case of the “Falun man”, the body of a miner who died in a deep (130 m) working was completely replaced by pyrite in just 60 years. At the same time, it was completely preserved appearance person. Perhaps this is where the famous legend about the “stone guest”, known among many peoples of the world, comes from.

Marcasite has the same chemical composition as pyrite, but a different crystal structure and is much less common than pyrite. In ancient times, pyrite and marcasite were identified. German miners of the late Middle Ages, calling both of these minerals sulfur pyrites, nevertheless distinguished marcasite into a special variety of “spear-shaped”, “radiant”, “comb” pyrites.

Only in 1814 was it established that marcasite was a special mineral, and in 1845. his first was compiled scientific description and the name “marcasite” stuck. The ancient Arabic "marcasite" originally also meant pyrite, antimony and bismuth. Jewelers still call pyrite “marcasite.”

2.2.5 Magnetite (Fe 3 O 4)

Magnetite is a very heavy mineral with a semi-metallic “dull” luster, iron-black color, with a blue or iridescent tarnish. Magnetite is characterized by black-gray crystals (Figure 17). According to one legend, magnetite was named after the Greek shepherd Magnes. Magnes was tending his flock on one of the inconspicuous plateaus in Thessaly and suddenly his staff with an iron tip and his sandals lined with nails were pulled towards a mountain made of solid gray stone. It is magnetism that is the rarest distinctive property of magnetite among minerals.

Figure 17 – Magnetite

Many scientists and poets have written about magnetite ancient world and the Middle Ages: Aristotle dedicated a special essay to him (“On the Magnet”), Lucretius and Claudian described it in verse, the fairy tales “A Thousand and One Nights” tell of a magnetic mountain in the middle of the sea, the force of gravity of which was so great that it pulled nails out of ships, which immediately collapsed and sank.

However, the real use of magnets was apparently first found in China, where in the 2nd century. BC. The compass was invented. The oldest known compasses in the countries of the East looked like a small cart on which an iron man sat and pointed with an outstretched hand to the south.

Thus, long before the discovery of metals, iron minerals attracted human attention and were widely used. Therefore, we can say with confidence that the “accidental” discovery of a method for smelting iron from ore was well prepared by the entire previous history of the development of civilization.

The most important geochemical feature of iron is the presence of several oxidation states. Iron in a neutral form - metallic - makes up the core of the earth, is possibly present in the mantle and is very rarely found in the earth's crust. Ferrous iron FeO is the main form of iron found in the mantle and crust. Iron oxide Fe2O3 is characteristic of the uppermost, most oxidized parts earth's crust, in particular, sedimentary rocks.

In terms of crystal chemical properties, the Fe2+ ion is close to the Mg2+ and Ca2+ ions - other main elements that make up a significant part of all earthly rocks. Due to crystal chemical similarity, iron replaces magnesium and, partially, calcium in many silicates. In this case, the iron content in minerals of variable composition usually increases with decreasing temperature.

Iron minerals

Iron is quite widespread in the earth's crust - it accounts for about 4.1% of the mass of the earth's crust (4th place among all elements, 2nd among metals). In the mantle and earth's crust, iron is concentrated mainly in silicates, while its content is significant in basic and ultrabasic rocks, and low in acidic and intermediate rocks.

A large number of ores and minerals containing iron are known. Ores are natural minerals containing iron in such quantities and compounds that the industrial extraction of the metal from them is economically feasible. The iron content in industrial ores varies widely - from 16 to 70%. Depending on the chemical composition, iron ores are used for smelting cast iron in their natural form or, if they contain less than 50% Fe, after beneficiation. Most of the iron ores are used for the smelting of cast iron, steel, and ferroalloys. In relatively no large quantities they are used as natural paints (ochre) and weighting agents for drilling clay solutions.

Of greatest practical importance are red iron ore (hematite, Fe2O3; contains up to 70% Fe), magnetic iron ore (magnetite, FeO.Fe2O3, Fe3O4; contains 72.4% Fe), brown iron ore or limonite (goethite and hydrogoethite and hydrogoethite, respectively FeOOH and FeOOH nH2O). Goethite and hydrogoethite are most often found in the weathering crust, forming so-called “iron hats”, the thickness of which reaches several hundred meters. They may also be of sedimentary origin, falling out of colloidal solutions in lakes or coastal areas of seas. In this case, oolitic, or legume, iron ores are formed. They often contain vivianite Fe(3PO4)2·8H2O, which has the form of black elongated crystals and radial aggregates.

Iron sulfides are also widespread in nature - pyrite FeS2 (sulfur or iron pyrite) and pyrrhotite. They are not iron ore - pyrite is used to make sulfuric acid, and pyrrhotite often contains nickel and cobalt.

Other commonly found iron minerals:

· Siderite -- FeCO3 -- contains approximately 35% iron. It has a yellowish-white (with a gray or brown tint if dirty) color.

· Marcasite -- FeS2 -- contains 46.6% iron. It occurs in the form of yellow, brass-like, bipyramidal rhombic crystals.

· Löllingite -- FeAs2 -- contains 27.2% iron and occurs as silvery-white bipyramidal orthorhombic crystals.

· Mispickel -- FeAsS -- contains 34.3% iron. It occurs in the form of white monoclinic prisms.

· Melantherite - FeSO4·7H2O - is less common in nature and is green (or gray due to impurities) monoclinic crystals with a glassy luster and brittle.

· Vivianite -- Fe3(PO4)2·8H2O -- occurs in the form of blue-gray or green-gray monoclinic crystals.

The earth's crust also contains other, less common iron minerals, e.g.

Lesson objectives:

Educational:

Based on students’ knowledge of the structure of metal atoms, the features chemical bond, properties of metals - simple substances and their compounds, study the structural features of the iron atom and trace the relationship between the structure of the iron atom, its properties and the properties of its compounds;
get acquainted with the most important iron compounds. Develop cognitive interest in the subject, realize interdisciplinary connections chemistry courses

, biology, history, geography and literature.

Developmental:
To develop students’ ability to analyze, compare, generalize and draw conclusions based on existing and newly acquired knowledge, both in chemistry and in other disciplines.
Instill search and independent work skills.

Continue work on developing skills in applying knowledge when solving theoretical and practical problems (building subject-matter competence). Educational:

During the lesson, promote the formation of a scientific worldview, communicative and information competence. Lesson type:

A lesson in learning new knowledge. Primary consolidation of new knowledge. Form of organization of educational activities of students: group work, predominant work - independent. Lesson with elements

technologies of critical thinking. Equipment:

PSCE, metal crystal lattices, videos confirming the chemical properties of iron and its compounds, reagents (iron powder, sulfur, solutions of hydrochloric and sulfuric acids, copper sulfate, sodium hydroxide, red and yellow blood salts, iron (II) sulfate, ferric chloride (III), potassium thiocyanate), multimedia equipment, a disk with a recording of the presentation, an electronic manual on the topic "Metals".

DURING THE CLASSES

I. Organizational moment (1-2 min) Stage 1

“Challenge”. At this phase, the knowledge available to students is updated, and interest in the issue under discussion arises.

Today we will continue our journey into the world of metals: we will not only explore the present, but also look into the distant past. The attention of visitors to the World Industrial Exhibition in 1958 in Brussels was attracted by the Atomium building. Nine huge metal balls, 18 meters in diameter, seemed to float in the air: eight at the tops of the cube, the ninth in the center. This was a model of the unit cell of crystalline alpha iron, magnified 165 billion times (slide 2)

The teacher announces the topic of the lesson: “Iron and its compounds” (slide 3)

Reception "Let's dig into memory"

Stage 2- Understanding new information. The teacher offers students new information that they must learn. At this stage, you may be asked to work with the text, fill out a matrix table, read the text with notes, or extract from the text.

Finding iron in nature.

Pupils are given printed material (The most important natural compounds of iron) and minerals containing iron are demonstrated.

Working with a table.

Answer the questions: a) What classes of inorganic compounds are included in the composition of iron minerals? b) Which mineral has the highest value mass fraction gland? c) In which regions of Russia is iron mined?

The most important natural iron compounds(slide 4)

Name of mineral	Chemical formula	Iron content (V %)	Major deposits
Magnetic iron ore (magnetite)	Fe3O4	up to 72	South Ural, Magnitogorsk, KMA, Kola Peninsula
Hematite (hematite)	Fe2O3	up to 65	Krivoy Rog, North. Ural, KMA
Brown iron ore (limonite)	2Fe 2 O 3 *3H 2 O	up to 60	Kerch, South Ural, Karelia, Lipetsk and Tula regions.
Spar iron ore (siderite)	FeCO3	up to 35	Yu. Ural, KMA, Kerch
Sulfur pyrite (pyrite)	FeS 2	up to 47	Ural, Altai, Transcaucasia

2. Physical properties gland. Iron crystal lattices (slide 5,6,7)

Reception "Cluster"

1. Write the key expression in the middle of the sheet: “Physical properties of iron”

2. Start writing down words or sentences that come to mind in connection with this task.

H. As you come up with ideas and write them down, begin to make connections between the ideas that feel right to you.

4. Write down as many ideas as come to your mind until all your ideas are exhausted.

At this stage of the lesson, it is possible to use the “Marking table” technique (working with the text, students fill out the table), for example:

"+" (I know)	"-" (Contradicts my knowledge)	"V" (This is new to me)	"?" (Unclear)
A simple substance with a metal bond. It has plasticity and malleability.		Iron symbol of the planet MARS	Has 4 allotropic modifications
Iron conducts heat and electricity.	The most common metal on Earth
Iron has a metallic luster and has magnetic properties	The most brilliant metal is iron.	Light is absorbed by the surface of the metal, and its electrons begin to emit their own, secondary, radiation waves.	Why does it conduct heat?

3. Position of the iron atom in the periodic table and structure of the atom(slide 8)

26 Fe)))) d - element VIII-B group, Ar = 56 1s 2 2s 2 2p 6 3s 2 3p 6 3d 6 4s 2

4. Chemical properties gland(Slide 9,10)

At this stage of the lesson, it is possible to use the “Self-Analysis” technique based on knowledge of the general properties of metals.

A) When heated, it interacts with many non-metals:

* with oxygen 3Fe + 2O 2 = Fe 3 O 4

* with chlorine 2Fe + 3Cl 2 = 2FeCl 3

* sulfur Fe + S = FeS

* with nitrogen 2Fe + N 2 = 2FeN

B) Water vapor is decomposed by hot iron: 3Fe + 4H 2 O = Fe 3 O 4 + 4H 2

C) Dilute HCL and H 2 SO 4 dissolve iron.

Fe + H 2 SO 4 = FeSO 4 + H 2 Fe + 2HCl = FeCl 2 + H 2

D) Does not react with concentrated nitric and sulfuric acids under normal conditions (acids passivate the metal)

E) When heated, the reaction with concentrated sulfuric acid proceeds according to the equation 2Fe + 6H 2 SO 4 = Fe 2 (SO 4) 3 + 3SO 2 + 6H 2 O

E) Interacts with salts: Fe + CuCl 2 = FeCl 2 + Cu

5. Properties of Fe +2 and Fe +3 compounds(slide 11, 12)

IRON COMPOUNDS
+2	+3
OXIDES
FeO - basic	Fe 2 O 3 - weakly amphoteric
General properties: 1. Do not dissolve in water
2. Reacts with acids
FeO+2HCl = FeCl 2 + H 2 O FeO + 2H + = Fe 2+ + H 2 O	Fe 2 O 3 + 6HCl = 2FeCl 3 + 3H 2 O Fe 2 O 3 + 6H + = 2Fe 3+ + 3H 2 O
3. React with acid oxides
FeO + SO 3 -> FeSO 4	Fe 2 O 3 + 3SO 3 -> Fe 2 (SO 4) 3
4. React with reducing agents
Fe0 + H 2 = Fe + H 2 O	Fe 2 O 3 + 3H 2 = 2Fe + 3H 2 O
Differences:
1. Unstable connections	1. React with alkalis: Fe 2 O 3 +2NaOH -> 2NaFeO 2 +H 2 O Fe 2 O 3 +2KOH+3H 2 O=2K
Iron hydroxides
Fe(OH) 2 - basic		Fe(OH) 3 - weakly amphoteric
General properties:
1. React with acids: Fe(OH) 2 +2HCl=FeCl 2 +2H 2 O Fe(OH) 2 + 2H + = Fe 2+ + 2H 2 O 2. At t 0 they decompose: Fe(OH) 2 = FeO + H 2 O		1. React with acids: Fe(OH) 3 +3HCl=FeCl 3 +3H 2 O Fe(OH) 3 + 3H + = Fe 3+ + 3H 2 O 2. At t 0 they decompose: 2Fe(OH) 3 = Fe 2 O 3 + 3H 2 O
Differences:
1. Oxidizes in air: 4Fe(OH) 2 +2H 2 O+O 2 =4Fe(OH) 3		1. React with alkalis: Fe(OH) 3 +KOH=K Fe(OH) 3 + OH - = -

6. Laboratory experiments. Qualitative reactions to Fe +2, Fe +3 ions.

1. To a solution of iron (II) sulfate - (FeSO 4) add a few drops of a solution of potassium hexacyanoferrate (III) - red blood salt K 3. We observe the precipitation of Turnboule's blue. What colour?

Write the reaction equation: FeSO 4 + K 3 ->

2. To a solution of iron (III) chloride - (FeCl 3) add a few drops of a solution of potassium hexacyanoferrate (II) K 4 - yellow blood salt. Note the color of the Prussian blue precipitate. Write down the reaction equation:

FeCl 3 + K 4 ->

3. Add a few drops of potassium thiocyanate (KCNS) solution to the iron (III) chloride solution. Observe the color of the solution. Write down the reaction equation:

FeCl 3 + KCNS ->

7. Practical significance iron salts(slide 13)

FeSO 4 * 7H 2 O - iron sulfate;
used in the textile industry for dyeing fabrics, in agriculture for treating seeds and controlling agricultural pests, producing ink.
FeCl 2 - iron (II) chloride; used to obtain pure iron, a component of antianemic drugs, a catalyst in organic synthesis.
FeCl 3 - iron (III) chloride; It is used in technology as an oxidizing agent in the production of organic dyes, in the textile industry - for etching fabrics when preparing them for dyeing, in medicine as a hemostatic agent, a component of tinting solutions in photography, a coagulant in water purification, for the determination of phenols. Fe 2 (SO 4) 3 - iron (III) sulfate; used as a chemical reagent in hydrometallurgical processing of copper ores, as a coagulant in purification

Wastewater, to obtain alum, Fe 2 O 3 pigment.

Stage 3

- Reflection, Contemplation. All information received at stage 2 is comprehended. Reflection and generalization of “what the child learned” in the lesson on this issue. At this stage, a supporting outline can be compiled in the student's notebook. In addition, the following can be done:

a) return to the call stage;

b) return to keywords;

c) return to inverted logical chains;

d) return to clusters.

It is possible to use the following techniques: "Confused logical chains"
or "Sinquain":
on the first line the topic is called in one word (noun)
the second line is a description of the topic in two words (adjectives).
the third line is a description of the action within the topic using three verbs.

the fourth is a four-word phrase showing the attitude towards the topic.

Task: From the proposed formulas of compounds, compose the genetic series Fe +2 (for the first option) and the genetic series Fe +2 (for the second option).

Fe(OH) 2, Fe, Fe(OH) 2, FeCl 3, Fe 2 O 3, FeCl 2, FeO

8. Homework (slide 14)

1. Write equations of chemical reactions that can be used to carry out the following transformations:

Fe -> FeCl 3 -> Fe(OH) 3 -> Fe 2 O 3 -> Fe -> FeSO 4 -> Fe(OH) 2 -> FeOa Fe -> Fe 3 O 4

2. Write the reaction equations for the stepwise hydrolysis of a Fe 2 (SO 4) 3 solution.

3. In Eq. chemical reaction arrange the coefficients using the electronic balance method: Fe 2 O 3 + KOH + KNO 3 -> K 2 FeO 4 + KNO 2 + H 2 O

Iron belongs to the group of native elements. Native iron is a mineral of terrestrial and cosmogenic origin. The nickel content is 3 percent higher in terrestrial iron compared to cosmogenic iron. It also contains impurities of magnesium, cobalt and other trace elements. Native iron has a light gray color with a metallic luster; inclusions of crystals are rare. This is a fairly rare mineral with a hardness of 4-5 units. and a density of 7000-7800 kg per cubic meter. Archaeologists have proven that native iron was used by ancient people long before they developed the skills to smelt iron from ore.

This metal in its original form has a silvery-white tint; the surface quickly becomes covered with rust in high humidity or in oxygen-rich water. This rock has good ductility, melts at a temperature of 1530 degrees Celsius, and can be easily forged into products and rolled. The metal has good electrical and thermal conductivity; it is additionally distinguished from other rocks by its magnetic properties.

When interacting with oxygen, the surface of the metal is covered with the resulting film, which protects it from corrosive effects. And when there is moisture in the air, iron oxidizes and rust forms on its surface. In some acids, iron dissolves and hydrogen is released.

The history of iron

Iron had a huge impact on the development of human society and continues to be valued today. It is used in many industries. Iron helped primitive man to master new methods of hunting and led to the development Agriculture thanks to new tools. Pure iron in those days was part of fallen meteorites. To this day, there are legends about the unearthly origin of this material. Metallurgy dates back to the middle of the second millennium BC. At that time, Egypt mastered the production of metal from iron ore.

Where is iron mined?

In its pure form, iron is found in celestial bodies. The metal was discovered in lunar soil. Now iron is mined from rock ore, and Russia occupies a leading position in the extraction of this metal. Rich deposits of iron ore are located in the European part, in Western Siberia and in the Urals.

Areas of use

Iron is essential in the production of steel, which has a wide range of applications. This material is used in almost every production. Iron is widely used in everyday life; it can be found in the form of forged products and cast iron. Iron allows you to give the product different shapes, so it is used in forging and creating gazebos, fences and other products.

All housewives use iron in the kitchen, because products made of cast iron are nothing more than an alloy of iron and carbon. Cast iron cookware heats up evenly, maintains temperature for a long time and lasts for decades. Almost all cutlery contains iron, and stainless steel is used to make dishes and various kitchen utensils and such necessary items as shovels, pitchforks, axes and other useful tools. This metal is also widely used in jewelry.

Chemical composition

Telluric iron contains impurities of nickel (Ni) 0.6-2%, cobalt (Co) up to 0.3%, copper (Cu) up to 0.4%, platinum (Pt) up to 0.1%, carbon; in meteorite iron, nickel ranges from 2 to 12%, cobalt is about 0.5%, and there are also impurities of phosphorus, sulfur, and carbon.

Behavior in acids: dissolves in HNO3.
In nature, there are several modifications of iron - the low-temperature one has a bcc cell (Im3m), the high-temperature (at temperatures > 1179K) the fcc cell (Fm(-3)m). Found in large quantities in meteorites. Widmanstätten figures appear in iron meteorites when etched or heated.
Origin: telluric (terrestrial) iron is rarely found in basaltic lavas (Uifak, Disko Island, off the western coast of Greenland, near Kassel, Germany). At both points, pyrrhotite (Fe1-xS) and cohenite (Fe3C) are associated with it, which is explained by both reduction by carbon (including from the host rocks) and the decomposition of carbonyl complexes such as Fe(CO)n. In microscopic grains, it has more than once been established in altered (serpentinized) ultrabasic rocks, also in paragenesis with pyrrhotite, sometimes with magnetite, due to which it arises during reduction reactions. Very rarely found in the oxidation zone of ore deposits, during the formation of swamp ores. Findings have been recorded in sedimentary rocks associated with the reduction of iron compounds with hydrogen and hydrocarbons.
Almost pure iron was found in lunar soil, which is associated with both meteorite falls and magmatic processes. Finally, two classes of meteorites - stony-iron and iron - contain natural iron alloys as a rock-forming component.

Native iron family (according to Godovikov)
Native iron group
< 2,9, редко до 6,4 ат. % Ni - феррит
< ~ 6,4 ат. % Ni - камасит

Native Nickel Group
> 24 at. % Ni - taenite
62.5 - 92 at. % Ni - awaruite Ni3Fe
(Ni, Fe) - Native nickel

Iron (English Iron, French Fer, German Eisen) is one of the seven metals of antiquity. It is very likely that man became acquainted with iron of meteorite origin earlier than with other metals. Meteoric iron is usually easy to distinguish from terrestrial iron, since it almost always contains from 5 to 30% nickel, most often 7-8%. Since ancient times, iron has been obtained from ores that occur almost everywhere. The most common ores are hematite (Fe 2 O 3,), brown iron ore (2Fe 2 O 3, ZN 2 O) and its varieties (swamp ore, siderite, or spar iron FeCO3,), magnetite (Fe 3 0 4) and some others . All these ores, when heated with coal, are easily reduced at a relatively low temperature, starting from 500 o C. The resulting metal had the appearance of a viscous spongy mass, which was then processed at 700-800 o With repeated forging.

In ancient times and the Middle Ages, the seven then known metals were compared with the seven planets, which symbolized the connection between metals and celestial bodies and the celestial origin of metals. This comparison became common more than 2000 years ago and is constantly found in literature until the 19th century. In the II century. n. e. iron was compared with Mercury and was called mercury, but later it began to be compared with Mars and called Mars, which, in particular, emphasized the external similarity of the reddish color of Mars with red iron ores.

Properties of the mineral

Origin of name: The designation of the chemical element is from the Latin ferrum, Iron - from the Old English word meaning this metal
Opening location: Qeqertarsuaq Island (Disko Island), Qaasuitsup, Greenland
Opening year: known since ancient times
Thermal properties: P. tr. Melting point (pure iron) 1528°C
IMA status: valid, first described before 1959 (before IMA)
Typical impurities: Ni,C,Co,P,Cu,S
Strunz (8th edition): 1/A.07-10
Hey's CIM Ref.: 1.57
Dana (7th edition): 1.1.17.1
Molecular Weight: 55.85
Cell parameters: a = 2.8664Å
Number of formula units (Z): 2
Unit cell volume: V 23.55 Å³
Twinning: by (111)
Point group: m3m (4/m 3 2/m) - Hexoctahedral
Space group: Im3m (I4/m 3 2/m)
Separateness: by (112)
Density (calculated): 7.874
Density (measured): 7.3 - 7.87
Type: isotropic
Reflected color: white
Selection form: Form of crystalline deposits: dense grains with irregular sinuous outlines, films, dendrites, and occasionally nuggets.
USSR taxonomy classes: Metals
IMA classes: Native elements
Chemical formula: Fe
Syngony: cubic
Color: Steel grey, grey-black, white on polished surface
Trait color: Gray-black
Shine: metal
Transparency: opaque
Cleavage: imperfect by (001)
Kink: hooked splintered
Hardness: 4 5
Microhardness: VHN100=160
Ductility: Yes
Magnetity: Yes
Literature: Zaritsky P.V., Dovgopolov S.D., Samoilovich L.G. Composition and genesis of the native iron ore occurrence in the town of Ozyornaya in the river basin. Chickens. - Bulletin of Kharkov University, 1986, No. 283 (Central Siberia) Meltser M.A. and others. Native iron in the gold-bearing veins of the Allah-Yun region and some questions of their genesis. - New data on the geology of Yakutia. Ya., 1975, p. 74-78

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Articles on the topic

Iron is one of the seven metals of antiquity.
It is very likely that man became acquainted with iron of meteorite origin earlier than with other metals

Deposits of the mineral Iron

Krasnoyarsk region
Russia
Kugda, Khatanga, Taimyr.

Iron ore is an important fossil product that humanity began to mine many centuries ago. Since ancient times, iron has found wide application in everyday life and other conditions of human society. One of the key advantages and properties of iron ore is the ability to make steel, obtained through the process of smelting it.

Iron ore can have different properties, mineral composition, as well as the percentage of impurities and metals depending on the type and location of its development. Finding places to mine iron ore minerals with the appropriate technical equipment is not a difficult task, since iron makes up more than 5% of the solid deposits of the earth's crust across the entire surface of the planet. According to Wikipedia and other reliable sources, iron ore is the fourth most common mineral mined in the world.

However, it is not possible to find this metal in nature in its pure form - it can be found in certain quantities in most known types and types of stone (rocks). Minerals (iron ore) are among the most profitable in terms of extraction. The quantitative content of iron in it depends on the nature of the origin of iron ore.

What does iron ore look like and what is it like?

As a key chemical element, iron is found in many rocks. However, not every such rock can be a potential raw material for mining and development. The feasibility of developing iron ores, as such, largely depends on the percentage composition.

Its mining began in earnest more than 3 thousand years ago, due to the ability to produce iron-based products of higher quality and durability in comparison with bronze and copper, which began to be mined even earlier. Even in those days, craftsmen working in smelters could accurately distinguish between types of iron ore.

Currently, it is customary to distinguish several types of raw materials suitable for subsequent smelting of useful metal:

magnetite;
magnetino-apatite;
Magnetino-titanium;
hydrogoethite-goethite;
hematite-magnetin.

An iron ore deposit with a compositional percentage of iron of 57% is considered rich. But, as mentioned above, it may be advisable to develop deposits in which the ore contains 26% of this useful metal. In rocks, iron predominates in the form of oxides. The remaining components are phosphorus, sulfur and silicas.

There are tables of iron ore that reflect its raw materials, chemical composition and percentage of iron. If we are guided by the numerical indicators of most of these tables, then we can conditionally divide valuable ores according to the degree of their richness and properties into 4 categories

very rich – base metal content more than 65%;
moderately rich - average iron percentage 60-65%;
moderate – from 45% or more;
poor - less than 45% of mined useful elements in general.

Depending on the amount of by-products included in the iron deposit being developed, more or less energy is required for processing. The efficiency of production of finished iron-based products largely depends on this.

Nature of origin

Most of the known mine types were formed under the influence of three main factors. The features and characteristics of iron ore actually depend on them.

Igneous formation. Igneous compositions were formed under the influence of high temperatures of magma or under conditions of high activity of ancient volcanoes. In fact, there were natural processes mixing and melting of rocks.

This type of mineral is a crystalline mineral compound characterized by a high percentage of iron content. Deposits of igneous fossils can usually be found in ancient formation zones in mountainous areas. It was in these places that the molten substances came as close as possible to the surface layers of the soil.

Metamorphic formation. In the process of this formation, sedimentary type minerals are formed. The essence of this process comes down to the movement of individual sections of the Earth's crust, during which certain layers, rich in certain elements, fall under the rocks that lie above.

Minerals that were formed during the next movement migrate closer to the earth's surface. Iron ore, which is formed during metamorphic formation, typically has a high percentage of useful metallic compounds and is not located too deep from the surface. One of the most common examples is magnetic iron ore, which contains up to 75% iron.

Sedimentary formation. In this case, the main factors for this type of mine formation are natural forces, in particular winds and water. Rock layers are destroyed and moved to lowlands - this is where they accumulate, forming separate layers. Water acts as a reagent, which leaches the starting materials. During such processes, deposits of brown iron ore are formed, which is a crumbly, loosened mass with a high content of mineral impurities and a percentage of iron of up to 35-40%.

Due to the different specifics of the formation of metamorphic rocks, raw materials are often mixed within layers with igneous rock, limestone and clay. In the same deposit, indicated by the corresponding sign on the map, deposits of different origins are found, which are mixed with each other. Places supposedly rich in sedimentary iron ores in this case are determined during geological exploration activities.

Basic properties and types. What ore is iron obtained from?

The most common type is considered to be red iron ore, which is based on hematite oxide. Its composition contains a minimum of by-products and over 70% iron.

The next most common is brown iron ore (limonite), which is an iron oxide containing H 2 O. As a rule, limonite contains about a quarter of the percentage of iron. In nature, brown iron ore can be found in the form of porous, loose rocks containing phosphorus and manganese. The ore contains clay as waste rock.

Magnetic iron ore contains a magnetic oxide, the properties of which are lost under conditions of strong heating. In nature, it is found much less frequently than the above-mentioned rocks and, in terms of the percentage of iron, in some cases is not inferior to red iron ore.

Iron spar is an ore rock containing siderite with a high clay content in its composition. This is a very rare breed, and due to the low iron content, it is mined much less frequently, especially when it comes to industrial use.

In addition to oxides, there are other types of iron ore, which are based on carbonates and silicates.

Geographical location of key deposits

All main deposits are usually divided into:

Metamorphogenic – quartzite deposits;
Exogenous – brown iron ore and other sedimentary rocks;
Endogenous – predominantly titanomagnetite compositions.

Similar ore deposits are found on almost every continent. Most of the iron ore deposits are located on the territory of the CIS countries, in particular the territory of Kazakhstan, Russia and Ukraine. Countries such as South Africa, India, the USA, Australia, Canada and Brazil can boast of fairly large reserves of iron ore accumulations. There are maps of iron ore deposits, both on a global scale and with more detailed indications of deposits on the territory of a particular state.

The importance of iron ore and the areas in which it is used

Mostly all industries in which these minerals are involved are associated with the metallurgical sector. For the most part, iron ore is used in the smelting of pig iron using a converter or open-hearth furnace. In turn, cast iron is widely used in many industrial sectors.

Today, another heavy-duty, anti-corrosion alloy, steel, is extremely popular and actively produced, for which iron ore minerals are also used. This is the most popular industrial alloy, which is famous for its corrosion resistance and high strength.

Steel and cast iron materials are used in the following industries:

rocket and military industries, production of special equipment;
mechanical engineering, including the manufacture of machine tools and other factory mechanisms;
automotive production (automotive frames, engine components, housings and other mechanical components are manufactured);
mining industry (production of heavy mining equipment and other special equipment);
construction – reinforcing materials, creation of a load-bearing frame.

Extraction methods

Methods and methods for extracting ore mineral resources from the subsoil depend on the depth at which the sought-for material lies. In this context, it is customary to distinguish three main methods:

Borehole method (hydraulic extraction) - to work in this way, specialists drill wells that reach rock layers. Tubular structures are placed in the resulting sections, through which the material is crushed and extracted using a powerful water jet. This is the least effective, stagnant and outdated method, which is rarely used these days.

Mine method - used provided that the layers lie deeper (up to 900 meters). First of all, mine sections are cut through and drifts are developed from them along the seam. The rock is crushed and delivered to the surface via special conveyors.

The quarry method, unlike the well method, is considered the most common. It is used to work at medium depths (up to 300 meters). Powerful excavators and rock crushing mechanisms are used for mining. After crushing, the material is loaded and transported directly to the processing plant.

How are iron ore materials enriched?

Because there are different types of ores based on how much iron the ore contains, less enriched materials are sent to special plants where they are sorted, crushed, separated, and agglomerated.

In general, there are 4 main methods of ore dressing:

Flotation. A specially prepared dusty mass is immersed in H 2 O with the addition of air and substances called flotation reagents. Hence the name of the process itself - flotation. They connect iron particles with air bubbles and raise them to the surface in a foamy form. Waste rocks settle to the bottom.

Magnetic separation. The most common method, based on the difference in the effects of magnetism on various components of the ore mass. Separation can be carried out in the case of wet and dry rocks. During processing, drum mechanisms equipped with powerful electromagnetic elements are used.

Gravity cleaning. To carry it out, special suspensions with a density lower than the density of iron and higher than the density of waste rock are used. Natural gravitational forces push the by-products upward, and the suspension absorbs iron particles and leaves them below.

Flushing. It is used to remove sand and clay from mined materials - to separate them, it is enough to use a water jet under high pressure. The process occurs under high pressure and provides up to 5% enrichment. This is a relatively small indicator, because this method is always used in conjunction with other methods.