How did it work?
Iron is a metal that readily combines with other elements to form compounds such as oxides. Rust is an example. Thus the metal is not found naturally but some of its compounds, termed ores, are plentiful.
Releasing the metal from the ore is called smelting and takes place in the furnace where heat and chemical reactions combine to release the iron in liquid form which pools at the bottom of the furnace. The waste products also melt but being lighter than the metal, they float on it. Both can be tapped, and run out from the bottom of the furnace to solidify on cooling.
The following link takes you to a BBC animation showing how a blast furnace like that at Whitecliff worked.
THE WHITECLIFF IRONWORKS
Scheduled Monument No 1021420
Location NGR: SO 56870 10149
Address 1 Whitecliff, Coleford GL16 8NB, UK
Reg. Charity No. 114775. A company limited by guarantee No. 6859885.
Registered Office: Security Office, Whitecliff Quarry, Coleford, GL16 8NB