About 25% of steelmaking plants in the USA are minimills. They are very efficient and relatively cheap to build compared to a traditional iron and steelworks.
In some parts of the world, minimills are developing alongside newer methods of iron production. The absence or shortage of coking coal in these areas has led to a search for new ways of reducing iron ore.
In the Middle East, for example, natural gas or crude oil products are used instead of coke to generate the gas that reduces the ore. The reducing gas that is made in this way is usually a mixture containing carbon monoxide and hydrogen.
To make iron, this mixed reducing gas is typically blown at about 800oC through a tall furnace that is packed with ore. At this temperature iron does not melt and the furnace product is a solid known as directly reduced iron (DRI). This metal can be processed in the Electric Arc Furnace in the same way as scrap metal.