Low hearth

The low hearth is a Four with internal combustion which was useful, since the age of iron, to transform the Minerai Fer (Hématite, Limonite, etc) into metal iron.

History

In Europe, the first low hearths appeared towards 1200 av. J. - C.

Towards the end of the Middle Ages, the furnace evolved to the Haut-fourneau in a broad northern half of Europe. Direct reduction with the low hearth was however practiced until the 19th century in the south of Europe (in the “ forging mills catalane ” of the Pyrenean area) and until the 20th century in other areas of the world.

Operation

The low hearth is presented in the form of a chimney of human size (one or two meters in height) in brick S and Terra cotta, in which one lays out in alternation a layer of iron ore and a coal seam of Bois. When fire is put, the Charcoal produces Carbon monoxide (Gaz CO) which comes to reduce the minerai : iron is present in the ore in oxidized form Fe₃O₄ or Fe₂O₃, by reaction with CO, it is formed fer :

Fe₃O₄ + 4CO → 3Fe + 4CO₂

The pulling of the furnace is assured either by natural ventilation, or by bellows, generally handbooks. The impurities which accompany the ore form a dairy which runs out with bottom of the furnace or in a pit spared in lower part of its base (“ furnaces with cuve ” of single use).

In the bottom of the furnace a spongy solid, made up of metal and slag accumulates, which one calls “ massiot ” or “ loupe ”. The metal obtained by this process is very heterogeneous. The massiot can be made up of iron and going steel from 0,02% to carbon 2%.

The magnifying glass is initially purified and welded, by repeated hammering, in order to withdraw slag and to make metal homogeneous. There nevertheless remain slag inclusions in the metal matrix. One obtains after this long process, a block of metal which could be formatted by the Forgeron to manufacture the Outil (plowshare of Charrue, Serpe, hooping of wheel…) or the Weapon.

See too

To produce a low hearth

External bonds

The Smelter' S Art - Experimental Iron Production At The Rockbridge Bloomery, a page of Washington and Lee University (WLU) explaining the manufacture of iron with a low hearth ( bloomery smelting )
Historical Background off Damascus blades
File on iron: Iron falls the mask This file on iron presents the realization of a traditional raw ground low hearth builds according to the known elements of the traditional modes of the age of iron (experiment of archeology). The objective was to try to find the same type of slags as those provided by the excavations.

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