Solid state ore reduction

The first production of iron from ore dates back to around 500 BC, and is thought to have taken place in the Austrian Alps. The technique employed was the reduction of ores to a solid state at high temperature. It involves charging several alternating layers of ore and charcoal into small furnaces. The charcoal provides the carbon needed to reduce the oxide to iron and form carbon dioxide. As it burns, it provides the energy to raise the charge to a temperature of around 1,000°C, the minimum temperature required to initiate the reduction reaction. The resulting material is a spongy, pasty mixture of iron, carbon and slag, known as bloom. This bloom is then refined and shaped by hot-hammering. This operation is long and arduous, and the quality of the resulting material still leaves much to be desired, as its carbon and impurity content is not controlled, and its characteristics are highly...