Impurities form in iron ore. Iron Ore
The basis of the foundations of ferrous metallurgy, its main raw material and source of iron is the mineral - iron ore ; Iron, like most metals, is not found in nature in its pure form.
Iron ore is made up of minerals that are divided into two groups: iron-containing minerals (ore minerals) and non-iron minerals, which form gangue.
IN ore minerals iron is in the form of oxides Fe 2 O 3 , Fe 3 O 4 , carbonates FeCO 3 , sulfides FeS 2 . Currently, more than 300 minerals containing iron are known.
magnetite and hematite
The characteristics of four of them, most commonly used in ferrous metallurgy, are presented in the table.
Main ore minerals
Name of ore mineral |
Name of iron ore |
Chemical formula |
Maximum iron content (wt.%) |
Magnetite |
Magnetic iron ore |
||
Hematite |
|||
Hydrohematite |
Brown iron ore |
n Fe 2 O 3 × m H2O |
|
Spar iron ore |
Based on iron content, iron ores are divided into poor and rich. The higher the iron content in the ore, the more profitable its processing. Unfortunately , currently the reserves of rich ores are almost exhausted, Therefore, poor ores with low iron content are involved in circulation. Direct extraction of iron from such ores is economically ineffective and technologically very difficult. Therefore, modern ferrous metallurgy includes, as a mandatory stage, preparation of iron ores for metallurgical processing.
This preparation includes several stages. Iron ore mined from the depths of the earth is first crushed to a size of 6-8 mm pieces, then the ore mineral is separated from the waste rock (this process is called enrichment). As a result we get concentrate with a higher iron content than the original ore. The concentrate is sintered into pieces measuring 30-40 mm (the process is called agglomeration, and the product is agglomerate), or balls with a diameter of 10-15 mm are formed from the concentrate (the process is called pelletization, and the product is pellets). Thus, an iron-containing material is obtained that is most suitable for further processing in order to extract iron from it.
When they say “iron” about something, they mean durable, strong, indestructible. It is not surprising to hear: “iron will”, “iron health” and even “iron fist”. What is iron?
History of the name
Iron in its pure form is a silver-colored metal, in Latin it is called Fe (ferrum). Scientists argue about the origin of the Russian name. Some believe that it arose from the word “jalja”, which means metal in Sanskrit, others claim that it is the word “zhel”, meaning “to shine”.
How did people get iron?
For the first time, iron found itself in the hands of a man, falling from the sky. After all, many meteorites were almost entirely iron. Therefore, objects made of this metal were depicted as blue - the color of the sky. Many peoples have myths about the heavenly origin of iron tools - supposedly they were given by the gods.
What is the "Iron Age"?
When man discovered bronze, the “Bronze Age” began. Later it was replaced by the “iron” one. This is the name given to the time when the Khalibs, the people who lived on the shores of the Black Sea, learned to melt special sand in special furnaces. The resulting metal was a beautiful silver color and did not rust.
Have gold items always been more highly valued?
In those days, when iron was smelted from meteorites, it was mainly used to make jewelry that only people of noble birth could wear. Often these jewelry had a gold frame, and in ancient Rome even wedding rings were made of iron. A letter has been preserved written by one of the pharaohs of Egypt to the king of the Hittites, where he asked to send him iron, promising to pay in gold in any quantity.
World's Wonders Made of Iron
In India, in Delhi, there is an ancient column more than seven meters high. It was made of pure iron back in 415 AD. But even now on it there is not a trace of rust. According to legend, touching the column with your back grants your cherished desire. Another grandiose iron structure is the Eiffel Tower. More than seven thousand tons of metal were required to make the symbol of Paris.
Where does iron come from?
To get iron, you need iron ore. These are minerals, stones in which iron is combined with various other substances. By purifying iron from impurities, the desired metal is obtained. For example, the raw material can be magnetic iron ore, which contains up to 70% iron. Iron ore is a black or dark gray stone. In Russia it is mined in the Urals, for example, in the depths of the mountain, which is called Magnetic.
How is ore mined?
Iron ore deposits are found not only in Russia, but also in Ukraine, Sweden, Norway, Brazil, the USA and some other countries. The reserves of this mineral are not the same everywhere; they begin to extract it only if it seems profitable, because development is expensive and will not pay off if there is too little iron.
Most often, iron ore is mined using the open-pit method. They dig a huge hole called career. It is very deep - half a kilometer deep. And the width depends on how much ore there is around. Special machines scoop out the ore, separating it from the unwanted rock. Then trucks take it to factories.
However, not every deposit can be developed in this way. If the ore is deep, you have to make mines to extract it. For a mine, they first dig a deep well, which is called a shaft, and below it there are corridors - drifts. The miners are coming down. These are brave people, they find ore and they blow it up, and then transport it piece by piece to the surface. The work of miners is very dangerous, because the mine can collapse, and there are dangerous gases below, and even in an explosion, people can get hurt, although they are very careful and follow safety rules.
How is iron obtained from ore?
But getting ore is not everything! After all, obtaining iron from ore is also a difficult process. Although they learned to smelt iron from ore a long time ago. In ancient times, blacksmiths smelted it; they were very respected people. Ore and charcoal were placed in a special furnace called a forge and then set on fire. However, the usual combustion temperature is not high enough for smelting, so the fire was fanned using a bellows - a device that blows air with great force. At first they were moved by hands, and later they learned to use the power of water. As a result of heating, a sintered mass was obtained, which the blacksmith then forged, giving the iron the desired shape.
Alloys
More often it was used (and is still used) not pure iron, but steel or cast iron. It is an alloy of iron and carbon dioxide. If the alloy contains more than 2% carbon, then cast iron is obtained. It is fragile, but it melts easily and can be given any shape. If carbon is less than 2%, then . It is very durable and is used to make many necessary things, cars, weapons.
Now, of course, other methods are used, although their principle is the same: smelting with the addition of carbon dioxide at high temperatures. Currently, electricity is used for this purpose.
Why does the human body need iron?
If a person lacks iron, he gets sick. This the metal is needed for the formation of hemoglobin, which delivers oxygen to every cell of the body. Therefore, you need to eat foods rich in iron - liver, legumes, apples.
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Iron Ore is the main raw material for the global metallurgical industry. The economies of different countries largely depend on the market for this mineral, which is why the development of mines is receiving increased attention throughout the world.
Ore: definition and features
Ores are rocks that are used for processing and extracting the metals they contain. The types of these minerals differ in origin, chemical content, concentration of metals and impurities. The chemical composition of the ore contains various oxides, hydroxides and carbon dioxide salts of iron.
Interesting! Ore has been in demand on the farm since ancient times. Archaeologists were able to find out that the manufacture of the first iron objects dates back to the 2nd century. B.C. This material was first used by the inhabitants of Mesopotamia.
Iron- a common chemical element in nature. Its content in the earth's crust is about 4.2%. But in its pure form it is almost never found, most often in the form of compounds - in oxides, iron carbonates, salts, etc. Iron ore is a combination of minerals with a significant amount of iron. In the national economy, the use of ores containing more than 55% of this element is considered economically feasible.
What is made from ore
Iron ore industry is a metallurgical industry that specializes in the extraction and processing of iron ore. The main purpose of this material today is the production of cast iron and steel.
All products made from iron can be divided into groups:
- Pig iron with high carbon concentration (above 2%).
- Foundry cast iron.
- Steel ingots for the production of rolled products, reinforced concrete and steel pipes.
- Ferroalloys for steelmaking.
What is ore needed for?
The material is used for smelting iron and steel. Today there is practically no industrial sector that can do without these materials.
Cast iron is an alloy of carbon and iron with manganese, sulfur, silicon and phosphorus. Pig iron is produced in blast furnaces, where the ore is separated from iron oxides at high temperatures. Almost 90% of the resulting cast iron is marginal and is used in steel smelting.
Various technologies are used:
- electron beam melting to obtain pure high-quality material;
- vacuum processing;
- electro-slag remelting;
- steel refining (removal of harmful impurities).
The difference between steel and cast iron is the minimum concentration of impurities. Oxidative smelting in open-hearth furnaces is used for purification.
The highest quality steel is smelted in electric induction furnaces at extremely high temperatures.
Ore differs in the concentration of the element it contains. It can be enriched (with a concentration of 55%) and poor (from 26%). It is advisable to use low-grade ores in production only after enrichment.
Based on their origin, the following types of ores are distinguished:
- Magmatogenous (endogenous) - formed under the influence of high temperature;
- Surface - settled remains of the element on the bottom of sea basins;
- Metamorphogenic - obtained under the influence of extremely high pressure.
Main mineral compounds containing iron:
- Hematite (red iron ore). The most valuable source of iron with an element content of 70% and a minimum concentration of harmful impurities.
- Magnetite. A chemical element with a metal content of 72% is distinguished by high magnetic properties and is mined from magnetic iron ores.
- Siderite (iron carbonate). There is a high content of waste rock, the iron itself is about 45-48%.
- Brown iron ores. A group of aqueous oxides with a low percentage of iron, with admixtures of manganese and phosphorus. An element with such properties is characterized by good recoverability and porous structure.
The type of material depends on its composition and the content of additional impurities. The most common red iron ore with a high percentage of iron can be found in different states - from very dense to dusty.
Brown iron ores have a loose, slightly porous structure of brown or yellowish color. Such an element often requires enrichment, but is easily processed into ore (high-quality cast iron is obtained from it).
Magnetic iron ores are dense and granular in structure, looking like crystals embedded in the rock. The color of the ore is characteristic black-blue.
How ore is mined
Iron ore mining is a complex technical process that involves diving into the depths of the earth to search for minerals. Today, there are two methods of ore mining: open and closed.
Open (quarry method) is a common and safest option compared to closed technology. The method is relevant for cases where there are no hard rocks in the working area, and there are no populated areas or utility systems nearby.
First, a quarry up to 350 meters deep is dug, after which iron is collected and removed from the bottom by large machines. After extraction, the material is sent on diesel locomotives to steel and iron factories.
Quarries are dug using excavators, but this process takes a lot of time. As soon as the machine reaches the first layer of the mine, the material is submitted for examination to determine the percentage of iron content and the feasibility of further work (if the percentage is above 55%, work in this area continues).
Interesting! Compared to the closed method, mining in quarries costs half as much. This technology does not require the construction of mines or the creation of tunnels. At the same time, the efficiency of work in open pits is several times higher, and the loss of material is five times less.
Closed mining method
Mine (closed) ore mining is used only if it is planned to maintain the integrity of the landscape in the area where ore deposits are being mined. This method is also relevant for work in mountainous areas. In this case, a network of tunnels is created underground, which leads to additional costs - the construction of the mine itself and the complex transportation of metal to the surface. The main drawback is the high risk to the lives of workers; the mine can collapse and block access to the surface.
Where is ore mined?
Iron ore mining is one of the leading areas of the economic complex of the Russian Federation. But despite this, Russia's share in world ore production is only 5.6%. World reserves amount to about 160 billion tons. The volume of pure iron reaches 80 billion tons.
Countries rich in ores
The distribution of minerals by country is as follows:
- Russia - 18%;
- Brazil - 18%;
- Australia - 13%;
- Ukraine - 11%;
- China - 9%;
- Canada - 8%;
- USA - 7%;
- other countries - 15%.
Significant deposits of iron ore have been noted in Sweden (the cities of Falun and Gellivar). In America, a large amount of ore was discovered in the state of Pennsylvania. In Norway, the metal is mined in Persberg and Arendali.
Ores of Russia
The Kursk magnetic anomaly is a large deposit of iron ore in the Russian Federation and in the world, in which the volume of unrefined metal reaches 30,000 million tons.
Interesting! Analysts note that the scale of mineral production at the KMA mines will continue until 2020, and there will be a decline in the future.
The area of the Kola Peninsula mines is 115,000 sq. km. Iron, nickel, copper ores, cobalt and apatites are mined here.
The Ural Mountains are also among the largest ore deposits in the Russian Federation. The main development area is Kachkanar. The volume of ore minerals is 7000 million tons.
The metal is mined in smaller quantities in the West Siberian basin, Khakassia, the Kerch basin, Zabaikalsk and the Irkutsk region.
Iron ore are called natural mineral formations that contain iron in large quantities and such chemical compounds that its extraction is possible and advisable. The most important are: magnetite, magnetite, titanomagnetite, hematite, hydrohematite, goethite, hydrogoethite, siderite, ferruginous chlorites. Iron ores differ in mineral composition, iron content, useful and harmful impurities, formation conditions and industrial properties.
Iron ores are divided into rich (more than 50% iron), ordinary (50-25%) and poor (less than 25% iron). Depending on the chemical composition, they are used for smelting cast iron in its natural form or after enrichment. Iron ores used to make steel must contain certain substances in the required proportions. The quality of the resulting product depends on this. Some chemical elements (besides iron) can be extracted from the ore and used for other purposes.
Iron ore deposits are divided by origin. Usually there are 3 groups: magmatic, exogenous and metamorphogenic. They can be further divided into several groups. Magmatogenous are formed mainly when various compounds are exposed to high temperatures. Exogenous deposits arose in valleys during the deposition of sediments and weathering of rocks. Metamorphogenic deposits are pre-existing sedimentary deposits that have been transformed under high temperature conditions. The largest amount of iron ore is concentrated in Russia.
The largest in Russia:
Bakchar iron ore deposit
This deposit is one of the largest such iron ore deposits in Russia and the world. It is located on the territory of the Tomsk region in the interfluve of the Andorma and Iksa rivers. The deposit was discovered by accident during mining exploration in the 1960s.
The Bakcharovskoe iron ore deposit covers an area of 16 thousand km2. Iron ore formations are located at a depth of 190 to 220 meters. The ores contain up to 57% iron, as well as admixtures of other chemical elements (phosphorus, vanadium, palladium, gold and platinum). The iron content in enriched ore reaches 95-97%. Iron ore reserves in this territory are estimated at 28.7 billion tons.
Currently, new technologies for field development are being introduced. It is planned to extract ore not by quarrying, but by borehole hydraulic mining.
Abagaskoe iron ore deposit
The Abagaskoye iron ore deposit is located in the Krasnoyarsk Territory, 186 km west of the city of Abakan in the territory of and. The deposit was discovered back in 1933, but its development began only 50 years later. The ores here are mainly magnetite, high-alumina, and magnesium.
The main ore mineral here is magnetite, and the minor ones are musketovite, hematite, and pyrite.
The Abagas iron ore deposit is divided into two zones: Southern (length over 2600 m) and Northern (2300 m). Balance reserves of iron ore amount to over 73 million tons. Development is carried out in an open way. Total average annual production of 4.4 million tons of ore with an iron content of 28.4%.
Abakan iron ore deposit
The Abakan iron ore deposit is located in Khakassia, near the city of Abaza. It is located in the northeastern spurs. Opened in 1856, it was originally called “Abakan Grace”. After the discovery, the development of ores was carried out periodically. From 1947 to 1959, enterprises for the extraction and enrichment of ores were built. From 1957 to 1962, the deposit was developed by open pit mining and then underground (400 m deep mine).
Abakanskoye is a magnetite ore deposit. It contains: magnetite, actinolite, chlorite, calcite, andesite and cobalt-bearing pyrite.
Explored reserves of ore with an average iron content of 41.7 - 43.4% with an admixture of zinc and sulfur amount to 140 million tons. Average annual production is 2.4 million tons. The industrial product contains about 47.5% iron. The centers of production and processing are the cities of Abaza, Abakan, Novokuznetsk.
Kursk magnetic anomaly
The Kursk magnetic anomaly is the most powerful iron ore basin in the world. Ore deposits on its territory are estimated at 200-210 billion tons, which is about 50% of the iron ore reserves on the planet. It is located mainly in the Kursk, Belgorod and Oryol regions.
Currently, the boundaries of the Kursk magnetic anomaly cover an area of over 160 thousand km2, covering the territories of nine regions of the Center and South of the country. The promising reserves of rich iron ores in the unique basin amount to many billions of tons, and ferruginous quartzites are practically inexhaustible.
The magnetic anomaly in this area was discovered back in the 18th century, but scientists started talking about its possible cause - magnetic ore deposits - only in the last century. Rich ores were discovered in 1931. The area is about 120 thousand km2. Ores: magnetite quartzites, high-grade iron ores in the weathering crust of ferruginous quartzites. Reserves of ferruginous quartzites are over 25 billion tons with an iron content of 32-37% and over 30 billion tons of rich ores (52-66% iron). The deposits are developed by both open-pit and underground methods.
The Kursk magnetic anomaly includes the Prioskol iron ore deposit and the Chernyanskoe iron ore deposit.
Iron ore is a natural mineral formation that contains iron in the amount necessary for its industrial extraction. Iron ore consists of various oxides, carbon dioxide, and ore minerals. Among the latter, it is important to highlight the most important ones - magnetite and iron luster, as well as brown and red iron ore. Swamp and lake ores are part of brown iron ore, and spherosiderite is one of the varieties of spar.
Ore minerals in nature are mixed with minerals without iron in the composition, such as clay or limestone. There is also a combination with igneous crystalline rocks.
There are cases when an accumulation of the above-mentioned minerals was found in one deposit, however, a specific type of mineral still remained predominant, others are simply genetically related to it.
Having obtained a general idea of what iron ore consists of, it is necessary to specify all the data obtained.
It is advisable to start with magnetic iron ore. So, it represents the formula Fe 2O4 oxide and ferrous oxide. Its pure form contains about 72% metallic iron, but such a pure form is very rare due to the fact that various impurities are added to it. These are mainly ores of other metals: zinc blende, for example, or copper pyrites, or sulfur pyrites. The rocks accompanying magnetic iron ore are chlorite, feldspar and a number of other rocks. Magnetic iron ore can be considered one of the most developed ores, because in nature its deposits are found both in layers and nests, and in places of rock eruptions even in entire rock formations.
The next thing to study is Fe 2 O3, or anhydrous iron oxide, in other words, iron luster. It contains about 69 – 70% metal and is one of the purest iron ores. It occurs in the form of continuous layers, as well as in gneisses and shales.
Red iron ore, usually dense and columnar iron oxide, is the source of iron deposits, as well as one of the main sources for the smelting of steel and cast iron.
Brown iron ore is an ore, more than half of which is represented by hydrous iron oxide. Brown iron ores contain various impurities, sometimes containing harmful substances, for example, sulfur, manganese or phosphorus. This iron ore is found very often, but the size of the deposits is very small.
The closest in composition to brown iron ores are considered to be bog and iron ores, which form the residue of iron oxide, clay and sand in the form of round “cakes” in the lake and swamp. Iron in such ores is about 40 - 45%, and due to their fusibility, they serve as a source of iron of not very high quality.
Sparite iron ore, which is present in recently appeared sedimentary formations, with an admixture of clay or carbonaceous matter, contains several percent more metallic iron.
When talking about ore mining methods, several options should be mentioned. The choice of a specific technology depends, first of all, on the economic and technical feasibility of the action.
For many years, the most used has been the so-called open method, the essence of which is to build a quarry and use specialized equipment for this. It should also be understood that this method can be rationally used for not very deep deposits.
For deeper deposits, the borehole hydraulic extraction method is suitable, during which a relatively deep well is drilled. A pipe with a water monitor is lowered into this well and a stream of water is passed, the purpose of which is to crush the rock. After this, the ore rises from the ground.