1) Operator of a metal plant 
An ironmaster is the manager, and usually owner, of a forge or blast furnace for the processing of iron. It is a term mainly associated with the period of the Industrial Revolution, especially in Great Britain. The ironmaster was usually a large scale entrepreneur and thus an important member of a community. He would have a large country house or ...
head of an ironworks
• (n.) A manufacturer of iron, or large dealer therein.
I'ron·mas`ter noun A manufacturer of iron, or large dealer therein. Bp. Hurd. 
the master of a foundry or ironworks; a manufacturer of iron.