Element symbol: Fe

Element Name: Iron

Atomic weight of element: 55.85

Element type: metal

Discovered by: year of discovery:

Discovery process:

Iron was discovered in ancient times.

Element description:

This is a bright silvery white metal. The density is 7.86 g/cm3. Melting point 1535℃, boiling point 2750℃. The common valence is +2 and +3, which has good ductility and thermal conductivity. Can also conduct electricity. Pure iron can be magnetized and demagnetized quickly. The ionization energy is 7.870 electron volts. Because of its active chemical properties, it is a good reducing agent. If there are impurities, it is easy to rust in humid air; In humid air containing acid gas or halogen vapor, rust will be faster. Soluble in dilute acid. Can be passivated in concentrated nitric acid. It can be combined with halogen, sulfur, silicon, carbon and phosphorus when heated. In addition to +2 and +3 valence oxides, there is also a composite oxide Fe3O4 (which is a magnetic oxide). Iron is an indispensable metal in the industrial sector.

Element source:

Iron is the most abundant element in the earth's crust. Magnetite, hematite, limonite and siderite are important iron ores. Monomer metals are usually made of coke, iron ore and Carboniferous stones. Pure iron can be obtained by reducing pure iron oxide with hydrogen. Iron with carbon content exceeding 1.7% is called pig iron (or cast iron). Iron melt with carbon content less than 0.2% is called wrought iron or wrought iron. Iron melt with carbon content between 1.7-0.2 is called steel. Pig iron is hard, but brittle; Steel is elastic; Wrought iron is easy to process, but softer than steel. Pig iron steelmaking is to reduce the carbon content in pig iron and remove impurities such as silicon, sulfur and phosphorus.

Element usage:

Its biggest use is steelmaking; It is also widely used to make cast iron and wrought iron. Iron and its compounds are also used as magnets, dyes (ink, blue printed cloth, rouge pigment) and abrasives (red iron powder). Reduced iron powder is widely used in metallurgy.

Element auxiliary data:

One of the main components of the crust. Iron is widely distributed in nature, but it was discovered and utilized later than gold and copper. First of all, there is no iron in the state of natural elements on the earth, which is easy to oxidize and rust. In addition, its melting point (1535℃) is much higher than that of copper (1083℃), and it is more difficult to smelt than copper.

Humans first discovered that iron is a meteorite falling from the sky, and the percentage of iron in meteorites is very high (90.85% in iron meteorites), which is a mixture of iron, nickel and cobalt. Archaeologists once found an axe made of meteorites in the ancient tomb; In the religious scriptures hidden in the pyramids of the fifth to sixth dynasties in Egypt, it was recorded that the thrones of important gods such as the sun god were made of iron at that time. Iron was considered as the most mysterious precious metal at that time, and the Egyptians simply called it "Shi Tian". In ancient Greek, "star" and "iron" are the same word.

1978, a Shang Dynasty tomb was excavated in Liuhe Village, Pinggu County, Beijing, and many bronzes were unearthed. The most striking thing is an ancient iron-edged bronze cymbal, which was identified as forged by meteorites. This not only shows that the earliest iron discovered by human beings came from meteorites, but also shows that the working people in our country knew iron and were familiar with its forging properties more than 3300 years ago, and realized the difference in nature between iron and bronze.

Because the source of meteorites is extremely scarce, the iron obtained from meteorites has little effect on production. With the maturity of bronze smelting technology, it has gradually created conditions for the development of iron smelting technology. The earliest artificial iron smelting in China appeared at the turn of the Spring and Autumn Period and the Warring States Period, about 2500 years ago. China's steelmaking technology also developed very early. 1978, the cultural relics excavation team of Changsha Railway Station Construction Project of Hunan Provincial Museum unearthed a steel sword from an ancient tomb, which was determined to be a tomb in the late Spring and Autumn Period from the shape, decoration and shape of the buried pottery. The steel used in this sword is medium carbon steel with a carbon content of about 0.5%, and the metallographic structure is relatively uniform, which indicates that it may be overheated.

The ironmaking skills of the ancient working people were also outstanding. The iron pillar erected behind the gate of a mosque near Delhi, India, is made of rather dull iron. How to produce such iron at that time was considered a miracle by modern people. According to human analysis, the iron content is more than 99.72%, and the rest is carbon 0.08%, silicon 0.046%, sulfur 0.006% and phosphorus 0. 1 14%.

A foundry worker named Bessemer initiated a new era of modern steelmaking. He announced his tiltable converter on August 1856+0 1.

With the development of industry, a lot of scrap steel and scrap iron appeared in production, construction and life, which could not be used in converter, so open hearth steelmaking appeared, which was founded by Siemens brothers in Germany and Martin brothers in France at the same time, and the time was 65438+early 1960s.