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The oldest known blast furnaces were built in Han China in the 1st century BC. However, cast iron artifacts found in China have been dated as early as the 5th century BC, so it is possible that the history of the blast furnace in china is older than presently known. These early furnaces had clay walls and used phosphorus-containing minerals as a fluxIn metallurgy Flux is an aid to melting; a material which by its chemical action facilitates soldering or brazing of metals. Such a flux applied to a metallic surface cleans it and renders it receptive to amalgamation with the solder or brazing metal.. The oldest known blast furnace in the West were built in SwedenThe Kingdom of Sweden Konungariket Sverige in Swedish) is a Nordic country in Scandinavia, in Northern Europe. It is bordered by Norway on the west, Finland on the northeast, the Skagerrak and the Kattegat on the southwest, and the Baltic Sea and the Gulf at Lapphyttan, sometime between 1150Events Ahus, Sweden gains city privileges City of Airdrie, Scotland founded King Sverker I of Sweden is deposed and succeeded by Eric IX of Sweden. Albrecht the Bear inhabits Brandenburg Peter the Lombard publishes Sentences University of Paris, now known and 1350Events Hayam Wuruk becomes ruler of the Majapahit Empire The Black Death ravages Europe (1347-1351) Births Manuel II Palaeologus, future Byzantine Emperor John Montacute, 3rd Earl of Salisbury (approximate date). Deaths March 27 King Alfonso XI of Castile. It is unclear whether the blast furnace was independently developed there, or whether the technology was transmitted to EuropeFor the band of the same name, see Europe (band . Europe is a continent forming the westermost part of the Eurasian supercontinent. Europe is bounded to the north by the Arctic Ocean, to the west by the Atlantic Ocean, to the south by the Mediterranean Se by the MongolsThe Mongol Empire was founded by Genghis Khan in 1206. At its height, it was arguably the largest contiguous empire in human history, stretching from Southeast Asia to Europe, covering 13. 8 million square miles or more than 35 million square kilometers..
In 1709Events January 12 Two-month freezing period begins in France The coast of the Atlantic and Seine River freeze, crops fail and at least 24. 000 Parisians die February 2 Alexander Selkirk is rescued from shipwreck on a desert island, inspiring the book Robi, Abraham DarbyAbraham Darby is the name of three generations of an English Quaker family that was key to the development of the Industrial Revolution. The first Abraham Darby b. circa 1678 d. March 8, 1717) was a Quaker who started his trade at Bristol where he develop developed a blast furnace that could be fired by coke instead of charcoal. Deforestation in Europe had progressed to the point that fuel-wood was becoming a strategic resource , and the use of a coal-derived fuel made blast-furnace based iron smelting significantly less expensive.
The blast furnace relied on the fact that the unwanted sulfur-iron compounds were lighter than the pure iron and iron-carbon mix, pig iron, that was its main product. The furnace was built in the form of a tall chimney-like cauldron lined with refractory brick. Coke, limestone and iron ore are poured in the top, which would normally burn only on the surface. Pre-heated air was blown into the middle, thus the "blast", allowing combustion in the middle of the mixture. The results of this localized burning was a liquid that sank to the bottom of the furnace, with the lighter materials on top. A valve was opened to allow the slag to pour out, and once emptied, another valve at the bottom opened to remove the pig iron.
The exact nature of the reaction is:
Fe2O3 + 3 CO → 2 Fe + 3 CO2
Air blown into the furnace reacts with the carbon in the coal to produce carbon monoxide, which then mixes with the iron oxide, reacting chemically to produce pure iron and carbon dioxide, which leaks out of the furnace at the top.
The temperature in the furnace typically runs at about 1500°C, which is enough to also decompose limestone ( calcium carbonate) into calcium oxide and additional carbon dioxide:
CaCO3 → CaO + CO2
The calcium oxide reacts with various acidic impurities in the iron (notably silica) and floats with the slag, thereby further purifying the iron.
The pig iron produced by the blast furnace is not very useful directly due to its high carbon content, around 4-5%, making it very brittle. Further processing was needed to reduce the carbon content for use as a construction material. For some time the products of the blast furnace was used almost directly as wrought iron after additional processing, the conversion to steel using the crucible technique was too expensive to operate on a large scale. However with the introduction of the Bessemer process the conversion to steel was also dramatically improved, and by the turn of the late 1800s almost all iron was being converted to steel before use.
The blast furnace remains an important part of modern iron production. Modern furnaces include cowper stoves to pre-heat the blast air to high temperatures in order to avoid cooling (and thus having to re-heat) the mix, and use fairly complex systems to extract the heat from the hot carbon dioxide when it escapes from the top of the furnace, further improving efficiency. The largest blast furnaces produce around 60,000 tonnes of iron per week, enough for about four cars per minute.
Metallurgists use the name cupola to refer to a cylindrical shaft type of blast furnace used for remelting metals (usually iron) before casting.| Politics | Business | Finance |
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