Lilleby smelteverk was a smeltmill located in Lilleby, Trondheim, Sør-Trøndelag county, Norway, next to City Lade. It is well known for having produced the world's cleanest ferrosilicon (an alloy that contains iron and silicon) for NASA. Shut down in December 20th, 2002, the production moved to Mo I Rana.
The building is demolished.