Diagram of the Krupp-Renn direct reduction process, which transforms iron ore in iron. This process was an efficient way to produce <a href="https://en.wikipedia.org/wiki/Direct_reduced_iron" class="extiw" title="en:Direct reduced iron">direct reduced iron</a> during the years 1930-1960.
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<span class="int-own-work" lang="en">Own work</span> from <a rel="nofollow" class="external text" href="http://aei.pitt.edu/40344/1/A4743.pdf">Communauté Européenne du Charbon et de l'Acier</a>