Editing Steel (section)

====Processes starting from pig iron====
[[File:Siemens Martin Ofen Brandenburg.jpg|thumb|An [[open hearth furnace]] in the Museum of Industry in [[Brandenburg]], Germany]]
[[File:Allegheny Ludlum steel furnace.jpg|thumb|White-hot steel pouring out of an electric arc furnace in [[Brackenridge, Pennsylvania]]]]
The modern era in [[steelmaking]] began with the introduction of [[Henry Bessemer]]'s [[Bessemer process|process]] in 1855, the raw material for which was pig iron.<ref>{{cite book |title=History of the Manufacture of Iron in All Ages |last=Swank |first=James Moore |isbn=0-8337-3463-6 |date=1892 |publisher=Burt Franklin}}</ref> His method let him produce steel in large quantities cheaply, thus [[mild steel]] came to be used for most purposes for which wrought iron was formerly used.<ref>{{cite book |chapter=Bessemer process |chapter-url= https://www.britannica.com/technology/Bessemer-process |volume=2 |page=168 |title=[[Encyclopædia Britannica]] |edition=online |date=2005}}</ref> The Gilchrist-Thomas process (or ''basic Bessemer process'') was an improvement to the Bessemer process, made by lining the converter with a [[basic (chemistry)|basic]] material to remove phosphorus.

Another 19th-century steelmaking process was the [[Siemens-Martin process]], which complemented the Bessemer process.<ref name="britannicaironandsteel" /> It consisted of co-melting bar iron (or steel scrap) with pig iron.

These methods of steel production were rendered obsolete by the Linz-Donawitz process of [[basic oxygen steelmaking]] (BOS), developed in 1952,<ref name="zs">{{cite news |last1=Sherman |first1=Zander |title=How my great-grandfather's Dofasco steel empire rose and fell, and his descendants with it |url= https://www.theglobeandmail.com/business/rob-magazine/article-how-my-great-grandfathers-dofasco-steel-empire-rose-and-fell-and-his/ |work=[[The Globe and Mail]] |date=4 September 2019}}</ref> and other oxygen steel making methods. Basic oxygen steelmaking is superior to previous steelmaking methods because the oxygen pumped into the furnace limited impurities, primarily nitrogen, that previously had entered from the air used,<ref>{{cite book |chapter=Basic oxygen process |title=[[Encyclopædia Britannica]] |date=2007}}</ref> and because, with respect to the open hearth process, the same quantity of steel from a BOS process is manufactured in one-twelfth the time.<ref name="zs" /> Today, [[electric arc furnace]]s (EAF) are a common method of reprocessing [[scrap|scrap metal]] to create new steel. They can also be used for converting pig iron to steel, but they use a lot of electrical energy (about 440 kWh per&nbsp;metric ton), and are thus generally only economical when there is a plentiful supply of cheap electricity.{{sfnp|Fruehan|Wakelin|1998|pp=48–52}}