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Steel industry developments
Minimills
In a large country such as the USA, the traditional centres of the steelmaking industry can be a very long way from their markets. These markets often exist in heavily populated, manufacturing regions that generate large volumes of scrap metal. In areas like this, steelmaking plants have developed that do not rely on a supply of Blast Furnace iron. They are called minimills. Minimills make only a small number of steel products for mostly local markets. They convert local scrap metal to steel in Electric Arc Furnaces before further processing takes place in secondary steelmaking and continuous casting facilities.

Raw materialsMeltingRefiningContinuous casting
Scrap
and
DRI
Electric
arc
furnace
Ladle
furnace
Caster
ReheatingTunnel
furnace
ShapingMill
Product

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.

Question 19

a) Make a list of the factors that have contributed to the growth of minimills in the USA

b) Where might you expect to find minimill sites in the UK? Explain your choice of location?

Question 20
Compare the methods that are used for making:

a) Blast Furnace iron and
b) directly reduced iron (DRI)

by completing this table:

 Blast Furnace ironDirectly reduced iron
FuelNatural gas or crude oil
Reducing gas
Typical furnace temperature
State of metallic productliquid
Typical furnace height40 metres
Continuous or batch process?Continuous