page 9
What is steel?
Routes to steel
Two methods of making steel are dominant in modern steel industries all over the world.
Pie chart graphic of different production methods
Figure 1. Pie chart to show realtive amounts of steel produced by EAF and BOS methods. The numbers are in millions of metric tonnes in 1997.
Route 1 Basic Oxygen Steelmaking (BOS)
The hot metal from the Blast Furnace contains up to 4.5% of carbon.

Steelmaking reduces the carbon content to a level that matches the customer’s requirements. This is often less than 0.1%. Basic Oxygen Steelmaking (BOS) makes steel from Blast Furnace iron and small amounts of scrap metal.

blast furnace iron + scrapBOS furnacesteel
Animation of uses of steel

Some uses of steels
Route 2 Electric Arc Furnace Steelmaking (EAF)
We also make steel in the UK using the Electric Arc Furnace (EAF). This is an electrically heated furnace that makes steel from scrap metal only.
scrapEAF furnacesteel
Most of the metal that is made in the BOS furnace is sold as bulk steel. More specialist steels are made in the Electric Arc Furnace, although this furnace is also capable of producing large volumes of other types of steel.
Unlike the manufacture of iron, steel production is not a continuous process. As we have already seen, there are different types of steel and the exact composition of a steel will depend on the customer’s specification. This is why steelmaking has to be a batch process.
Question 9

Give some examples of industrial or commercial processes which are:

(a) continuous
(b) batch