There are signs of the use of iron since the fourth millennium BC, by the Sumerians and Egyptians.
In the second and third millennium BC, more and more iron objects (distinguished from iron from meteorites by the absence of nickel) appear in Mesopotamia, Anatolia and Egypt. However, its use seems to be ceremonial, being a very expensive metal, more so than gold. Some sources suggest that it may have been obtained as a by-product of obtaining copper.
Between 1600 BC C. and 1200 BC. C. Its use is increasing in the Middle East, but it does not replace the predominant use of bronze.
Between the centuries BC. C. and a. C. there is a rapid transition in the Middle East from bronze to iron weapons. This rapid transition was perhaps due to a lack of tin, rather than an improvement in iron-working technology. This period, which occurred on different dates depending on the location, is called the Iron Age, replacing the Bronze Age. In Greece it began to be used around the year 1000 BC. C. and did not reach Western Europe until the century BC. C. The replacement of bronze by iron was gradual, as it was difficult to manufacture iron pieces: locate the mineral, then melt it at high temperatures to finally forge it.
In Central Europe, it emerged in the century BC. C. the Hallstatt culture (replacing the urn field culture, which is called the "first Iron Age", as it coincides with the introduction of this metal).
Around 450 BC. C. the La Tène culture developed, also called the "second Iron Age." Iron is used in tools, weapons and jewelry, although bronze objects are still found.
Along with this transition from bronze to iron, the "carburization" process was discovered, consisting of adding carbon to iron. Iron was obtained as a mixture of iron and slag, with some carbon or carbides, and was forged, removing the slag and oxidizing the carbon, thus creating the product already in shape. This wrought iron had a very low carbon content and could not be easily hardened by cooling in water. It was observed that a much harder product could be obtained by heating the piece of wrought iron in a bed of charcoal, and then submerging it in water or oil. The resulting product, which had a steel surface, was harder and less brittle than the bronze, which it began to replace.
In China, the first iron used also came from meteorites, with wrought iron objects having been found in the northwest, near Xinjiang, from the century BC. C. The procedure was the same as that used in the Middle East and Europe. In the last years of the Zhou dynasty (550 BC) it was possible to obtain cast iron (product of the fusion of pig iron). The mineral found there has a high phosphorus content, which means it melts at lower temperatures than in Europe and other places. However, for quite some time, until the Qing dynasty (around 221 BC), it did not have a great impact.
Cast iron took longer in Europe, as the temperature was not sufficient. Some of the earliest samples of cast iron have been found in Sweden, in Lapphyttan and Vinarhyttan, from 1150 to 1350.
In the Middle Ages, and until the end of the century, many European countries used the Catalan forging as a steelmaking method. Iron and low-carbon steel were obtained using charcoal and iron ore. This system was already implemented in the 19th century, and it was possible to reach up to about 1200 °C. This procedure was replaced by the one used in blast furnaces.
Initially, charcoal was used to obtain iron as a heat source and as a reducing agent. In the 19th century, in England, charcoal became scarce and more expensive, and this led to the use of coke, a fossil fuel, as an alternative. It was first used by Abraham Darby, at the beginning of the century, who built a "blast furnace" at Coalbrookdale. Likewise, coke was used as a source of energy in the Industrial Revolution. In this period the demand for iron was increasing, for example for its application in railways.
The blast furnace evolved over the years. Henry Cort, in 1784, applied new techniques that improved production. In 1826 the German Friedrich Harkot built a blast furnace without masonry for smoke.
Towards the end of the century and the beginning of the century, iron began to be widely used as a structural element (in bridges, buildings, etc.). Between 1776 and 1779, the first cast iron bridge was built, built by John Wilkinson and Abraham Darby. In England it was first used in the construction of buildings, by Mathew Boulton and James Watt, at the beginning of the century. Other works from that century are also known, for example the Crystal Palace built for the 1851 World's Fair in London, by the architect Joseph Paxton, which has an iron frame, or the Eiffel Tower, in Paris, built in 1889 for the World's Fair, where thousands of tons of iron were used.