There are various kinds of metals that hukna civilization heavily use. One of these metals and maybe the most important one is iron element. Also, we use it in various applications and nearly in all the engineering and technological applications, we use it in various phases. In automotive, aerospace, and household appliances, it has a very widespread use compared with other metals. In this article, we will try to give some information about these elements from different viewpoints. Furthermore, we would like to give satisfying information to people from all the other fields who are dealing with it in different means. You can find information on these issues on this element;
- What is iron element?
- A brief history of this element
- The chemical properties of it,
- The mechanical and physical properties of it,
- Production of this element from ores and sources,
- Applications that they use this material in human civilization,
- Biggest producers around the world,
- Iron prices and economics of this element in the world.
- Importance of iron in human health.
What is Iron Element?
What is iron? It is a very open-ended question and we can give the answer in different ways for this question. From different viewpoints, we can answer this question in different ways. But if we need to answer from a chemical and scientific viewpoint, this is an element that has an atomic number of 26 and the symbol Fe in the periodic table. This is classified as a transition metal in the periodic table.
A Brief History of the Iron Element
Throughout history, they used it heavily in different means. Starting from the Sumerians and Egyptians around 4000 BC, people used this element in making spearheads and other sharp goods. But in general, people used gold and silver generally to make these goods because the iron trend to bo corroded easily.
In 3500 BC, some metal beads are found that are made from this element. They made these metal beads from meteorites and meteorite-sourced elements. Because they include an evidentiary amount of Nickel.
Around 2000 BC, other goods are found in the Anatolian and Mezoptamia soil made from the iron element. So, people made these goods that from iron do not include Nickel which means they did not produce this element from meteorites. But according to the different sources, the iron element is much more expensive than gold and silver these years. Because of this, people used it only for rare ceremonial events.
The use of iron in different applications such as war clothes and other tools sharply increased in the Middle East around 1600 BC. The transition from bronze to iron takes place with the carburization of the iron element.
What are the Chemical Properties of This Element?
As we stated above, the this element has an atomic number of 26 and it is classified as a transition metal. Furthermore the electron alignment of the this element is 2, 8, 14, 2. The electronegativity of the iron element is 1.83 Pauling scale. The group of the iron element in the periodic table is 8 and the period and block are 4 and d.
The atomic radius of the iron element is around 126pm and the covalent bond radius is 125pm.
Iron element is heavily get oxidize in the atmosphere and this property of this element is one of the most problematic properties.
Mechanical Properties of This Element
Iron element has very distinct and preferred mechanical properties. Because of these properties, people use it is in most applications.
- The general state of it at room temperature is solid. But it has a very malleable nature. We can shape pure iron in different forms easily.
- The density of the pure iron is 7,86 g/cm³ which is very heavy around other engineering materials.
- The melting point of this element is 1538 °C which is quite high if we compare with other elements. In most metal casting processes, this value is familiar.
- The boiling point of the this element is 2861°C if you want to boil the iron element.
- The heat of fusion and heat of evaporation of this element is 13.81 kJ/mol and 340 kJ/mol respectively.
- The heat capacity of the iron element is 25.10 j/(mol.K).
- The electrical resistance of this element is 96,1 nΩ·m which is quite low if we compare with other elements. We call it as a very good electrical conductor because of this reason.
- The heat conductivity of it is 80,4 W/(m·K) which makes the this element a very good heat conductor.
- The Mohs hardness value of this element is 4.0.
- The Vickers hardness of it is 608 MPa.
- The Brinell hardness of this element is 490 MPa.
So, these are the general mechanical properties of iron element that shows why it is the most common metal that human civilization is actively using it.
Steels and cast irons are very important engineering and production materials in metallurgy. And these are the most used materials in industry. Furthermore, almost in every product and every application, we use ferrous materials. Because of that, the supply is very important are in metallurgy.
Ores are the natural sources which we use in general production processes as raw material. Ores are not pure in terms of iron, there are other impurities or chemical compositions. So there must some processes applied to these ores to decompose raw iron or ‘pure’ from them. Also, general ores have iron content between 50-70% inside them. We obtain the general ores from nature are; hematite, magnetite, siderite and limonite.
We need to use some kinds of other materials to reduce the iron from their ores. These materials are; coke and limestone. So, coke is a high carbon fuel that we produce by heating bituminous coal in a limited oxygen atmosphere for several hours, followed by water spraying in special quenching towers. It is a very good fuel to reduce it from ores and produces CO is a very important gas to reduce iron from its ore.
Limestone is a type of rock that includes very high amount of calcium carbonate. So we can use to react with impurities inside these ores and remove them from iron to obtain pure element.
In machining processes, casting processes and various types of manufacturing processes that we apply to ferrous metals, and they produce lots of scraps. We use these scraps also as source, and it is a very important iron source in terms of recycling of materials.
How Do We Produce It?
Iron element production may be the most common practice in the metal production and metal industry. We obtain from the nature ore of hematite(Fe2O3) and magnetite(Fe3O4). These are different oxides of this metal. So, there must be a process that dioxide these ores to obtain pure iron elements from them.
With the application of hot gas(roughly around 1650 Celsius degrees), the coke burns. Carbon monoxide comes as hot gas and it also emerges from the combustion of coke. The iron charge is come from the top of the furnace to the below side with the application of hot gases. The hot gas includes also, carbon dioxide, oxygen, vapor, hydrogen, and nitrogen. We can summarize the production of it from ores by following chemical reactions inside the blast furnaces;
In general, we use blast furnaces or cupola furnaces to produce pure iron element. In these furnaces, the oxides of ores are filled. And limestone(CaCO3) is also filled with this ore. The purpose of this mixture is to get the required chemical reaction to separate the oxygen from the this element.
In these furnaces filled with elements stated above, hot air comesfrom the bottom of the furnace. With this air blast, the furnace gets very hot around 2100K temperatures. At the top side of the furnace, the temperatures are around 500K. This temperature variation in iron element production is very important.
With the application of hot oxygen these chemical reactions occur;
2C + O2 = 2CO(gas) + heat
We use the carbon and the carbon monoxide to reduce the pure iron from the oxidized ore with the chemical reactions;
Fe2O3 + 3C = 2Fe + 2CO2
Fe2O3 + 3CO2 = 2Fe + 3CO2
As the chemical reaction continues, the molten pure element reduces from the bottom of the furnace. But this pure element has some degrees of impurities that are chemically bond with oxygen. Sulfur and phosphorus are the common impurities in the produced pure element. We apply the oxidation process of these impurities as the final purifying process to pure iron element. The obtained element has nearly 99% of purity.
This element in blast furnaces called as pig iron which has roughly 4% of carbon and other impurities inside it. We use cupola furnaces commonly to obtain gray cast iron from pig iron. To produce steel from pig iron, we must control the impurities in much more precise manner.
The Iron-Carbon Alloys And Fe-C Phase Diagram
The iron-carbon phase diagram and these systems are the most important binary systems in engineering. Steels, cast irons, and various kinds of applications are dependent on iron-carbon systems. We also explained the tin-lead phase diagram and nickel-copper phase diagrams which are also very important in metallurgy and engineering.
The phases and phase diagram is slightly complex, compared with other diagrams. The horizontal axis of the Fe-C diagram shows the percentage of carbon inside the Fe-C systems. The solubility limit of carbon inside this element is very low. So the diagram above shows up to 6.11% of carbon content which is also the solubility limit of carbon inside this element. The two vertical axes are showing the temperature on which the right side is Celsius, the left side is Fahrenheit.
If we take a look at the pure iron element from the left side, there are lots of phases. The first phase that starts from the ambient temperature of pure element that we call as the alpha solid phase which we also call ferrite. At 912 Celsius degrees of temperature, the austenite phase of element is formed. At 1394 celsius degrees, the delta phase occurs up to the melting point of pure iron element which is 1539 Celsius degrees.
Lattice Structures of Them
If we take a look at the lattice structures of the phases, the alpha and beta phases of pure element have a BCC lattice structure, and the gamma phase which is between these phases has an FCC lattice structure.
As we explained in another article, if the carboın content of the iron-carbon alloy is between 0-2.07%, we call this alloy as steel. Steel is one of the most important metals in industry.
At the 0.77% carbon and 723 Celsius degrees point, called eutectoid composition. Steels that have carbon content bigger than 0.77% we call hyper-eutectoid and we call the other ones as hypo-eutectoid steels. There is another point that we call the eutectic point that is occurring at 4.3% of carbon and 1130 Celsius degrees temperature.
If the carbon content is between 2.07-6.11%, we call this alloy as cast iron.
There is an F3C phase in the diagram above that is prominent at low temperatures that we call cementite. Cementite is the hard and brittle phase of iron-carbon alloy which is solid also.
Difference between Steel and Cast Iron
We generally use ferrous engineering metals generally for production of commercial customer products. So engineering metals are generally classified as ferrous and nonferrous metals. Ferrous metals includes very important commercial material inside it: Fe-C alloys. You can see Fe-C metals wherever you look. So these Fe-C alloys are generally classified as; Steels and Cast Irons.
FeC metals are the ferrous metals this element that includes a specified amount of carbon inside the. The features of FeC metals are generally changes with the carbon content inside it. So this carbon content defines the FeC metals either Steel ot Cast Iron.
In general applications, the carbon percent inside this element, ranges from 0.005% to 6.67%. There are various kinds of FeC metals that used in thousands of casual applications or professional applications. But if we take a look at the, what is the difference between steel and cast iron is like that;
Steels includes up to 2% of carbon inside this element. But most general steel applications are ranging from around 0.2% to 1.1% of carbon content inside it.
Also cast irons include from 2% to 6.67% of carbon content inside it.
Which Applications that We Use This Element?
It has the vast majority of applications that are very useful for human civilization. Maybe it is very hard to state all the applications in that we mainly use. But we stated the most important applications that we use this material mainly.
Steel is one of the most used structural materials in engineering and applications. They are corrosion-resistant and mechanically very high-strength materials. Compared with other high-strength materials, steel is very cheap. And also, we produce steel with the alloying element of carbon that we alloy with this element. We add the 0.1-2.11% of carbon content to iron to produce steel. Steel has very good characteristics compared with it. Also, we add other alloying elements to obtain different characteristics such as stainless steel.
We use stainless steels generally as general structural parts such as automobile body elements, sheet metal products of automotive external parts, and high-strength applications such as steel apartment doors.
In the sheet metal industry, we use steel commonly. Because of its very good formability, we use steel sheets in sheet metal production techniques. In general, we use steel sheet metal parts as outer coatings of different machinery such as automotive, machine tools, coating of movable parts from human touch… Also, we can use high thickness sheet metal as structural parts such as seats of busses, etc.
With the changing percentage of carbon content, the mechanical characteristics of steel change. With the increasing amount of carbon, the strength of the steel increases but the formability of steel decreases. High alloyed and high carbon content steels are more brittle if we compare with low carbon steels. We use high carbon steels in the general production of cutter blades, knives, etc. We prefer low carbon steels as sheet metal external coatings.
Also, the machinability of steel is very good and we can produce nearly all kinds of parts with the steel machining processes.
Pig Iron Production
Pig iron production is a very important intermediate process between the production of pure elements and steel and cast iron. Furthermore, they are produced after the production of pure element with the redox process. 5-6% of carbon is added to the pure element to obtain it. This is used by different producers to produce cast iron or steel. So, they adjust the carbon content and the other alloying elements to obtain the required type of steel or this element.
Cast Iron Production
If we increase the percentage of the carbon content of iron above 2.11%, the material classification is called cast iron. Also, the top limit of the carbon percentage of the cast iron is 6%. The reason that these percentages of carbon content in this element are called cast iron, is they are very good capabilities of casting. So, rteel is not a good material to be cast. Molten ones have very good fluidity through casting channels and have very good shaping characteristics.
With the increasing amount of carbon in these systems, the casting capabilities increases but the brittle nature of the cast iron also increases. At 6% of carbon, cast iron has a very brittle structure like bricks or ceramics.
The most important characteristic of it is the capability to absorb mechanical vibrations. Because of this feature of cast irons, they are used in the machinery bases to prevent the vibrations and excitations that are coming from the other sides. In machine tools, the machine bases that carry all the parts and components of machine tools are made from them. It is because they are very strong both for static and dynamic loads and it absorbs the external vibrations to improve the machining accuracy.
Types of Cast Iron
Cast iron is a very common material in engineering and it is obtained with special processes from iron ores. Cast iron is the iron-carbon alloys that includes carbon ratio around 2,11-6,4%. So there are bunch of types of cast irons between these ratio.
Gray Cast Iron: Gray cast iron has the biggest market around other types. It includes 2.5-4% of carbon and 1-3% of silicon inside this element. There is a phenomenon in the structure that is flakes of carbon elements. When we brake gray cast iron, these carbon flakes gives gray color on the surface of this cast iron. Gray cast iron has very good vibration damping property which is a attractive material at engine blocks, basis of tool machinery and applications that has vibrations that we must like them. It is a very brittle material which means ductility of it is very low. Compression strength of gray cast iron is much more high if we compare with tensile strength. Machinability of it is also superior because of internal lubrication property.
Ductile Iron: It has the same alloying element ratios with gray cast iron, but the geometric shapes or carbon that we create inside the ductile iron are spheroids, instead of flakes like in gray one. We can obtain this structure can with special chemical threatments at solidification phase. Ductile ones has ductile property as its name implies, and has very good wear resistance and high strength. We can use in machinery components.
White Cast Iron: The chemical composition of white cast iron has less amount of carbon and silicon, compared with other types. And also, there are no such carbon flakes or spheroids in the structure of white cast iron. With rapid solidification, carcbon elements stay bonded with these elements in the form of Fe3C which we call as cementite. Because of that, there is no carbon precipitation in white cast iron. When its broken, the color of teh surface is white that gives the name of it. White cas iron has very good strength, hard and brittle.
Malleable Iron: If we apply heat treatment to the white cast iron to separate the carbon as graphite aggregates, we obtain malleable one. The ductility of it is very high up to 20% of elongation.
Alloy Cast Irons: We can alloy cast irons also to obtain specific properties. For example, we can apply heat treatment to some of cast irons to obtain martensite microstructure. We can obtain corrosion resistant ones with addition of chromium and nickel.
Production of Iron Element in the World
The production of it must be examined in two-stage: production of ore and production of pig iron. Pig iron is the form of pure element that is obtained by ores. And there is a very big difference between the production or mining of ores and the production of pig iron. Because the production of pure element requires some different technology compared with the extraction of ore.
Production of Iron Ore in the World
If we take a look at the production of ore in the world, Australia is the leader country. In the world, the general production of usable element ore is around 2.5 million tonnes. And the 930.000 tones of ore are produced in Australia which holds around 37.2% of the total production. So in the procurement to the world, Australia has a very important place around other countries. The second biggest ore producer is Brazil with 480.000 million tonnes. Ths percentage of iron ore production in Brazil is around 19.2% which is very high. Furthermore, China is the third country in the production of ore with 350.000 tonnes and 14% of the total ore production. The rest of the other producers are like this;
- Australia: 930.000 million tonnes.
- Brazil: 480.000 million tonnes.
- China: 350.000 million tonnes.
- India: 210.000 million tonnes.
- Russia: 99.000 million tonnes.
- South Africa: 77.000 million tonnes.
- Ukraine: 62.000 million tonnes.
- Canada: 54.000 million tonnes.
- The US: 48.000 million tonnes.
- Kazakhstan: 43.000 million tonnes.
- Other countries: 147.000 million tonnes.
Production of Pig Iron in the World
Pig iron is the most common type of production of pure element in the world. According to the 2015 data, the total pig iron production is around 1180 million metric tonnes. The biggest pig iron manufacturer is Chine with 710 million metric tonnes. In addition, the percentage of the total pig iron production in China is 60.12% which is very high compared with other countries. The second-biggest producer of pig iron is Japan with 84 million metric tonnes which make 7.11% of the total production. Also, the third one is India with 54 million metric tonnes which make up 4.6% of the total pig iron production. Other countries;
- China: 710 million metric tonnes.
- Japan: 84 million metric tonnes.
- India: 54 million metric tonnes.
- Russia: 51 million metric tonnes.
- South Korea: 47 million metric tonnes.
- Brazil: 30 million metric tonnes.
- Germany: 28 million metric tonnes.
- The US: 26 million metric tonnes.
- Ukraine: 25 million metric tonnes.
- The UK: 9 million metric tonnes.
- Other countries: 101 million metric tonnes.
You can see there is no parallel relation between ore production and pig iron production in the world.
Prices and Economics of Iron Element in the World
Iron is the most important material that is used by most of the industrialized countries in the world. So, the economics and prices of it are very important factors in the technology and other products in which the main material is iron or iron-based materials.
While examining the prices of it, we should not think about the investment behaviors of iron. Because this is not used as an investment tool such as gold and silver. In the examination of the gold prices, we need to consider the investor behaviors because a very big amount of gold is used as an investment tool. The most important factors that are affecting the prices in the world;
- Production rate of ore and pig iron,
- The demand for ore and pig iron from different industries,
- Logistics of it,
- Effects of politics on the factors above.
Production and Demand of Iron Element
Like other commercial materials and tools, it has a specific demand and production balance. According to the production of pig iron and ore data, the biggest demand for ore comes from China. So, the biggest importer of ore is China. China produces the biggest percentage of pig iron and it makes China the biggest exporter of pig iron to other countries. The most industrialized countries that are importing pig iron are generally, Japan, Germany, the US, and the UK. So, there is a very big logistics of pig iron between China and western countries.
As a result, the political and economical situations between China and the western countries will affect the prices directly.
Pig iron supply has also a very important effect on prices. The biggest ore miner country is Australia. So, there is a very big export of ore from Australia to China. This means the economical and political situations between Australia and China will affect prices heavily.
Logistics of This Element in the World
If we take a closer look at the importing and exporting activities of iron throughout the world, logistics lines are very obvious. There is a very big pig iron logistics between China and the western countries. These logistics are taking place with the sea transport system. If there will be new developments in sea transportation both technologically and politically between China and western countries, the prices will be affected by this.
Also, pig iron production and exportation to China in Australia has a very big logistics web. The logistics between China and Australia are also a very important factor in iron prices.
Iron Prices in the World
We take a look at the chart that shows the ore prices through the years, there is no stability. Stable increments or decrements are generally expected from investment tools because of investor behavior.
You can see the sharp increments and sharp decrements in the ore prices. The reason for these sharp increments and decrements can be because of the various reasons that we stated above. But we can use the variables above to make estimations of the ore prices.
Importance of Iron for Health
Iron is a very important mineral for our health and our body to absorption of other important minerals such as calcium, copper, and the production of various enzymes by the red blood cells.
Plants are taking it from the soil. And by eating plants, we are taking this element from the plant in sufficient amounts. The sufficient amount of iron for the human body is around 8-10 mg/day. The best nutrients to take the sufficient amount of iron to our bodies; are animal offals, fish, beans, spinach, and wheat.
The deficiency of iron leads to anemia which shows itself as a bleaching color of the tissue.
In this article, we tried to give sufficient and the most general information about an iron element from different viewpoints. The information about iron can be enhanced but we would like to hold the scope of this article to a specific level to be understood by all the readers.
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Because it has very unique mechanical and chemical properties to be used in such applications. Also, the ease of alloying with carbon to produce very high-quality materials at very low prices makes them very special among other metals.
It did not come from anywhere in the world. It is the fourth most abundant element in the world and the core of the world is largely composed of this element. Because of content of the core, our planet has a protective magnetic area from harmful radiation rays from the Sun.