Question: Who invented the process to remove impurities by blasts of cold air blown through heated iron?
Disambiguated questions and answers: question: What Englishman invented the process to remove impurities by blasts of cold air blown through heated iron?
What American independently discovered  the process to remove impurities by blasts of cold air blown through heated iron?
answer: Henry Bessemer
William Kelly
Natural Questions answer: Song Dynasty (from the Wikipedia article "Bessemer process")