Iron is an element that is familiar to every person on our planet. And this is not surprising. Indeed, in terms of its content in the earth's crust (up to 5%), this component is the most common. However, only the fortieth portion of these reserves can be found in deposits suitable for development. The main ore minerals of iron are siderite, brown iron ore, hematite and magnetite.
origin of name
Why does iron have such a name? If we consider the table of chemical elements, then in it this component is marked as "ferrum". Abbreviated as Fe.
According to many etymologists, the word "iron" came to us from the Pre-Slavic language, in which it sounded like zelezo. And this name passed from the vocabulary of the ancient Greeks. They called the metal so famous today “iron”.
There is another version. According to her, the name "iron" came to us from Latin, where it meant "star". The explanation for this lies in the fact that the first samples of this element discovered by people had a meteorite origin.
Use of iron
In the history of mankind, there was a period when people valued iron more than gold. This fact was recorded in Homer's Odyssey, which states that the winners of the games hosted by Achilles were given, in addition to gold, a piece of iron. This metal was extremely necessary for almost all artisans, farmers and warriors. And it was the huge need for it that became the best engine for the production of this material, as well as the further technical progress of its manufacture.
9-7 centuries BC. considered the Iron Age in the history of mankind. During this period, many tribes and peoples of Asia and Europe began to develop metallurgy. However, iron remains a high demand today. Indeed, until now it is the main material used for the manufacture of tools.
Cheese product
What is the technology for producing critical iron, which mankind began to mine at the dawn of the development of metallurgy? The very first method invented by mankind was called raw-cheese. Moreover, it was used for 3000 years, without changing from the time of the end of the Bronze Age to the period until the 13th century. a blast furnace was not invented in Europe. This method was called raw-cheese. Hens were built for him from stone or clay. Sometimes the material for their walls were pieces of slag. The last version of the hearth was coated on the inside with refractory clay, to which sand or crushed horn was added to improve quality.
What makes critical iron? “Raw” meadow or swamp ore was laid in the prepared pits . The smelting space of such furnaces was filled with charcoal, which was then heated up well. At the bottom of the pit was a hole for air supply. Initially, it was blown in with manual furs, which were later replaced by mechanical ones.
In the very first horns, natural traction was organized. It was carried out through special holes - nozzles, which were located on the walls of the lower part of the furnace. Often, the ancient metallurgists provided air supply through the use of a design that made it possible to obtain the effect of a pipe. They created a high and at the same time narrow inner space. Very often, such stoves were built at the foot of the hills. In these places there was the largest natural wind pressure, which was used to increase traction.
As a result of the ongoing process, the conversion of ore into metal took place. In this case, the waste rock gradually flowed down. At the bottom of the furnace, iron grains formed. They stuck together, turning into the so-called “kritz”. This is a loose spongy mass saturated with slag. In the furnace, the cry was white-hot. It was in this state that they removed it and quickly forged it. Pieces of slag just fell off. Next, the resulting material was welded into a monolithic piece. The result was screaming iron. The final product externally resembled a cake.
What was the composition of critical iron? It was an alloy of Fe with carbon, which was very small in the final product (if we consider the percentage ratio, then no more than hundredths).
However, the screaming iron that people received in the raw-iron furnace was not very solid and durable. That is why products made from such material quickly failed. Spears, axes and knives bent and did not remain sharp for very long.
Steel
In the production of iron in furnaces, along with its soft lumps, those that had a higher hardness were also found. These were pieces of ore in close contact with charcoal during the smelting process. A person noticed this pattern and began to specifically increase the area in contact with coal. This made it possible to carbonize iron. The resulting metal began to satisfy the needs of craftsmen and those who used products made from it.
This material was steel. It is still used in the manufacture of a huge number of structures and products. Steel smelted by ancient metallurgists is critical iron, which contains up to 2% carbon.
There was such a thing as mild steel. It was screaming iron, which contained less than 0.25% carbon. If we consider the history of metallurgy, it is precisely mild steel that was produced at the initial stage of cheese-production. What is the name for screaming iron? There is its third variety. When it contains more than 2% carbon, it is cast iron.
Invention of the blast furnace
The critical method of producing iron using raw-iron furnaces was highly dependent on the weather. Indeed, for such a technology it was important that the wind necessarily blow into the manufactured tube. It was the desire to get away from the vagaries of the weather that led the person to create furs. These were the devices necessary to fan the fire in a syrup-burning furnace.
After the appearance of bellows, the hens for metal production were no longer built on the hillsides. People began to use stoves of a new type, called "wolf pits." They were structures, one part of which was in the ground, and the second (domnica) towered above it in the form of a structure made of stones fastened together by clay. At the base of such a furnace there was an opening into which a tube of bellows was inserted to inflate the fire. The coal laid in the house was burned, after which it was possible to get the cry. She was pulled out through a hole that formed after the removal of several stones from the bottom of the structure. Then the wall was restored and the furnace was filled with ore and coal to start all over again.
Critical iron production was constantly improved. Over time, Domnica began to build larger. This necessitated an increase in the productivity of the bellows. As a result, coal began to burn faster, saturating iron with carbon.
Cast iron
What's the name of high carbon cricket iron? As mentioned above, it is so common today cast iron. Its distinctive feature is the ability to melt at relatively low temperatures.
Screaming iron - cast iron in solid form - could not be forged. That is why the ancient metallurgists at first did not pay any attention to him. From one blow with a hammer, this material simply shattered into pieces. In this regard, cast iron, like slag, was initially considered a waste product. In England, this metal was even called "pig iron." And only over time, people realized that this product, while it is in liquid form, can be poured into molds to obtain various products, for example, cannonballs. It is thanks to this discovery in the 14-15 centuries. Blast furnaces for the production of pig iron began to be erected in industry. The height of such structures reached 3 meters or more. With their help, cast iron was smelted for the production of not only cores, but also the guns themselves.
Blast furnace development
The real revolution in the metallurgical business occurred in the 80s of the 18th century. It was then that one of the Demidov clerks decided that for greater efficiency in the operation of blast furnaces, air should not be supplied to them through one, but through two nozzles, which should be located on both sides of the hearth. Gradually, the number of such nozzles grew. This allowed us to make the blasting process more uniform, increase the hearth diameter and increase the productivity of the furnaces.
The development of blast furnace production was also facilitated by the replacement of charcoal, for the sake of which forests were cut down, with coke. In 1829, in Scotland, the Klade plant was first used to blow hot air into a blast furnace. Such an innovation significantly increased the productivity of the furnace and reduced fuel consumption. Nowadays, the blast furnace process has been improved, replacing part of the coke with natural gas, which has an even lower cost.
Damask
What is the name of screaming iron, which has unique properties that were used in the manufacture of weapons? We know this material as damask. This metal, like Damascus steel, is an alloy of iron and carbon. However, unlike its other types, it is a screaming iron with good qualities. It is elastic and hard, and also capable of giving exceptional sharpness in the blade.
The metallurgists of many countries have tried to solve the secret of damask production for more than a century. A large number of recipes and methods were proposed that included the addition of ivory, precious stones, gold and silver to iron. However, the secret of damask steel was revealed only in the first half of the 20th century by the remarkable Russian metallurgist P. P. Anosov. He took the screaming iron, which was laid in a furnace with charcoal, where open fire was burning. The metal melted while being saturated with carbon. At this time, it was covered with slag from crystalline dolomite, sometimes with the addition of pure iron oxide. Under such a layer, the metal was very intensely released from silicon, phosphorus, sulfur, and oxygen. However, that was not all. The resulting steel had to be cooled as slowly and calmly as possible. This allowed the formation, first of all, of large crystals having a branched structure (dendrites). There was such cooling directly in the furnace, which was filled with hot coal. At the next stage, skillful forging was performed, in which the resulting structure was not supposed to collapse.
The unique properties of damask subsequently found explanation in the works of another Russian metallurgist D.K. Chernov. He explained that dendrites are refractory but relatively mild steel. The space between their “branches” in the process of solidification of iron is filled with more saturated carbon. That is, mild steel is surrounded by harder. This explains the properties of damask, concluded in its viscosity and at the same time high strength. Such a steel hybrid during smelting retains its tree-like structure, turning it only from rectilinear to zigzag. The peculiarity of the resulting drawing largely depends on the direction of the blows, the strength, as well as the skill of the blacksmith.
Damascus steel
In antiquity, this metal was the same damask steel. However, somewhat later, Damascus steel began to be called material obtained by forging from a large number of wires or strips. These elements were made of steel. Moreover, each of them was characterized by a different carbon content.
The art of manufacturing such metal reached its greatest development in the Middle Ages. For example, in the structure of the well-known Japanese blade, researchers found about 4 million steel threads of microscopic thickness. Such a composition made the manufacturing process of weapons very laborious.
Production in modern conditions
Ancient metallurgists left a model of their skill not only in weapons products. The most striking example of pure critical iron is the famous column located near the capital of India. Archaeologists have determined the age of this monument of metallurgical art. It turned out that the column was built another 1.5 thousand years ago. But the most amazing thing is that today it is impossible to detect even small traces of corrosion on its surface. The material of the column was subjected to rigorous research. It turned out that this is pure critical iron, which contains only 0.28% of foreign impurities. Such a discovery amazed even modern metallurgists.
Over time, screaming iron gradually lost its popularity. Metal smelted in an open-hearth or blast furnace began to be in greatest demand. However, when applying these methods, a product of insufficient purity is obtained. That is why recently the oldest way to produce this material, which allows you to produce metal with the highest quality characteristics, has received its second life.
What is critical iron called today? It is familiar to us as direct reduction metal. Of course, screaming iron today is received differently than in antiquity. For its production, the most modern technologies are used. They allow you to release a metal that has virtually no impurities. In production, tube-type rotary kilns are used. Such structural elements are used for firing various bulk materials using high temperatures in the chemical, cement and many other industries.
What is the critical iron called now? It is considered clean and is used when receiving a method that, in essence, is not much different from the one that existed in ancient times. All the same, metallurgists use iron ore, heated in the process of obtaining the final product. However, to date, raw materials are initially subjected to additional processing. It is enriched, creating a kind of concentrate.
Modern industry uses two methods. Both of them allow you to get critical iron from the concentrate.
The first of these methods is based on bringing the raw material to the required temperature using solid fuel. Such a process is very similar to that carried out by the ancient metallurgists. Instead of solid fuel, a gas that is a combination of hydrogen and carbon monoxide can be used.
What precedes the receipt of this material? What is the name of screaming iron today? After heating the iron ore concentrate, pellets remain in the furnace. It is from them that they subsequently produce pure metal.
The second method used to reduce iron is very similar in technology to the first. The only difference is that pure hydrogen is used as fuel for heating the metallurgical concentrate. With this method, iron is obtained much faster. That is why it is distinguished by higher quality, because in the process of interaction of hydrogen with enriched ore, only two substances are obtained. The first of these is pure iron, and the second is water. It could be assumed that this method is very popular in modern metallurgy. However, today it is used infrequently, and, as a rule, only for the release of iron powder. This is explained by the fact that it is rather difficult to obtain pure hydrogen both in terms of solving technical issues and because of economic difficulties. A difficult task is the storage of the resulting fuel.
More recently, scientists have developed yet another, third way of producing reduced iron. It involves the production of metal from ore concentrate, without going through the stage of its transformation into pellets. Studies have shown that with this method, pure iron can be produced much faster. However, this method has not yet been introduced in industry, as it requires significant technological changes and a change in the equipment of metallurgical enterprises.
What is the name of screaming iron today? We know this material as direct reduction metal, sometimes it is also called sponge metal. This is a cost-effective, high-quality, environmentally friendly material that does not have impurities of phosphorus and sulfur. Owing to its characteristics, critical iron is used in engineering industries (aircraft, shipbuilding, and instrumentation).
Fechral
As you can see, today, using the most modern technologies, such material as critical iron is used. Fechral is also a popular alloy. In addition to iron, it contains components such as chromium and aluminum. Nickel is also present in its structure, but not more than 0.6%.
Fechral has good electrical resistance, high hardness, works wonderfully with high-alumina ceramics, has no tendency to ulcerative corrosion and is heat-resistant in the atmosphere in which sulfur and its compounds, hydrogen and carbon are located. But the presence of iron in the alloy makes it quite fragile, making it difficult to process the material in the manufacture of various products.
Fechral finds its application in the manufacture of heating elements for laboratory and industrial furnaces, the maximum operating temperature of which is 1400 degrees. Sometimes parts from this alloy are used for another purpose. They are placed in household heating appliances, as well as in electrical heaters. Fechral was widely used in the production of electronic cigarettes. Also, an alloy of iron, aluminum and chromium is in demand in the field of manufacturing resistive elements. It can be, for example, brake resistors of electric locomotives.
From fechral release wire, as well as thread and tape. Sometimes circles and bars are obtained from it. All these products are used in the manufacture of various forms of heaters for electric furnaces.