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Iron


Iron
Free native iron in the Earth's crust, unlike copper, almost does not occur. But it is part of many minerals and spread much wider non-ferrous metals. In ancient times, it could produce literally everywhere - from the lake, marsh, meadow and other ores. However, compared with the metallurgy of copper, iron and steel it is a very complicated process. Iron melts at 1539 degrees. This high temperature was totally unavailable to ancient masters. Therefore, the iron man came into use much later copper. Its widely used as a material for the manufacture of weapons and tools only began in the 1st millennium BC, when he became known syrodutny iron reduction method (however, some people have learned to iron metallurgy much earlier, for example, the tribes that inhabited the territory of modern Armenia , were able to obtain iron from the ore early in the 3rd millennium BC).
The most common iron ores (magnetite, hematite and limonite) are either iron compound with oxygen (iron oxide), or ferric hydroxide. In order to isolate the metallic iron of these compounds is necessary to recover it - that is to take away his oxygen. Of course, the ancient masters had no idea about the complicated chemical process that occurs in the reduction of iron. However, watching the "melting" of ore, they eventually established a number of important laws, which formed the basis of the simplest methods of iron production. First of all, our ancestors noticed that for iron does not necessarily bring it to the melting point. Metallic iron can be produced at much lower temperatures, but it should be more fuel efficient than the smelting of copper, and this fuel must be of better quality. It is also necessary that the fire was as a "hot". All this required a special furnace device and melting conditions.

As a rule, starting the "melting" iron master first dug a round hole, which inside wall coated with a thick layer of clay. On the outer side of this hole was supplied hole for air injection. Then, over the rounded lower portion constructed in the form of an upper cone. The fuel used charcoal. He fell asleep in the bottom of the oven - in a hole. Top layers stacked on it charge - ground ore and coal. At the top peppered thick layer of coal. Once the fuel is ignited at the bottom, it started strong heating of the ore. When this chemical was oxidation reaction of carbon (coal) and the reduction of iron. In the form of tiny petals pasty iron, which were three times heavier than the slag and settles down sinking at the bottom of the furnace. As a result, the bottom hole going weld soft iron com - bloom, weighing from 1 to 8 kg. It consisted of a soft metal with voids filled with solid slag. When the "melting" came to an end, the oven was broken and removed from her Critz. Further processing takes place in the smithy, where Critz again warmed in the furnace and treated with blows of the hammer to remove slag. The metallurgy of iron forging for many centuries became the main type of metal working and blacksmithing has become the most important manufacturing industry. Only after forging iron has gained satisfactory quality. Pure iron, however, can not be used due to its softness. The economic importance was only an alloy of iron with carbon. If the resulting metal contained between 0, 3 and 1, 7% carbon steel was obtained, that is iron, which has acquired a new property - the ability to quenching. For this purpose made tool is heated red hot, and then cooled in water. After hardening, it becomes very hard and gained remarkable cutting quality.

In natural air inflow into the furnace temperature rose no higher than 1000 degrees. Already in ancient times it was observed that from the same ore more iron can be obtained and a better quality if oven artificially pumping air through the bellows. Fur made of skins supplied dulcitol and drives the hand movement. With the help of nozzles into the furnace and bellows pumped raw unheated air, hence the name of the whole process. However, in this method, only the temperature can rise up to 1200 degrees, and been removed from the ore is not more than half of the iron contained therein.

As a public and a cheap material, iron very soon penetrated all branches of production, life and military affairs and has made a revolution in all spheres of life. Iron ax and a wooden plow with an iron plowshare it possible to master the farming peoples who until then it was completely inaccessible. Only after the spread of iron farming in most peoples has become an important branch of industry. Iron gave Craftsman tools a hardness and severity, which could not withstand any stone or bronze. They were the basis on which began to flourish other crafts. These major shifts ended the primitive society. It was replaced by a more developed - a class society.

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