Extraction of Metals

The Blast Furnace

Up to 1709, furnaces could only use charcoal to produce iron.  However, wood (which is what charcoal is made from) was becoming more expensive, as forests were being cleared for farmland and timber.

Coal was a possible alternative to wood, but although it was cheap and plentiful, it wasn't a feasible fuel for making iron, because it contained sulphur, and this made the iron too brittle to be of any use.  However, in 1709, a man called Abraham Darby finally succeeded in extracting iron using coke(impure carbon).

The purpose of a blast furnace is to chemically reduce and physically convert iron oxides into liquid iron.  Iron or (mainly called haematite), coke and limestone are dumped into the top, and preheated air is blown into the bottom. 

The raw materials require 6 to 8 hours to descend to the bottom of the furnace where they become the final product of liquid **** and liquid iron.  Liquid iron is denser than liquid **** and therefore the **** layer forms on the top of the iron layer.  The waste gases formed in the furnace escape from the top.

What happens inside a blast furnace?

Coke is impure carbon…