Editing Pig iron (section)

==History==
{{see also|Ferrous metallurgy}}
[[File:Casting pig iron, Iroquois smelter, Chicago.jpg|thumb|upright=1.1|Casting pig iron at the Iroquois smelter in [[Chicago]] between 1890 and 1901]]
The Chinese were already making pig iron during the later [[Zhou dynasty]] (which ended in 256&nbsp;BC).<ref name="Wagner">Wagner, Donald. ''Iron and Steel in Ancient China''. Leiden 1996: [[Brill Publishers]]{{ISBN?}}{{page?|date=September 2022}}</ref> Furnaces such as [[Lapphyttan]] in Sweden may date back as far back as the 12th century; and some in the [[County of Mark]] dating back to the 13th century, which is now part of [[Westphalia]], Germany.<ref>Several papers in ''The importance of ironmaking: technical innovation and social change: papers presented at the Norberg Conference, May 1995'' ed. Gert Magnusson (Jernkontorets Berghistoriska Utskott H58, 1995), 143–179.</ref> It remains to be established whether these northern European developments were derived from the Chinese ones. Wagner<ref>{{Cite journal |last1=Golas |first1=Peter |year=1995 |title=Donald B. Wagner : Iron and Steel in Ancient China |url=https://www.persee.fr/doc/befeo_0336-1519_1995_num_82_1_2347 |journal=Bulletin de l'École Française d'Extrême-Orient |volume=82 |issue=1 |pages=426–428}}</ref> has postulated a possible link via Persian contacts with China along the [[Silk Road]] and Viking contacts with Persia,<ref name="Wagner" /> but there is a chronological gap between the Viking period and Lapphyttan.

Smelting and producing [[wrought iron]] were known in ancient Europe and the Middle East, but it was produced in [[bloomery|bloomeries]] by [[direct reduction]]. Small [[prill]]s of pig iron dispersed in [[slag]] are produced in all iron furnaces, but the operator of a bloomery had to avoid conditions causing the [[phase transition]] of the iron into liquid in the furnace, as the prill globules or any resulting pig iron are not malleable so can't be hammered in a single piece. Alternatively, [[Decarburization|decarburizing]] the pig iron into steel was an extremely tedious process using medieval technology, so in Europe before the [[Middle Ages]] the prills were discarded with the slag.<ref>{{Cite web |title=Medieval Iron in Society II. Papers and discussions presented at the symposium in Norberg, May 6–10, 1985. |url=https://www.jernkontoret.se/sv/publicerat/bergshistoria/bergshistoria/rapport-h-39 |access-date=2023-12-15 |website=Rapport H 39 - Jernkontoret |language=sv}}</ref>