2. Ferrous metals

Talking book

Iron minerals from the Earth's surface undergo different processes to obtain pure iron and its alloys: steel and cast iron.

Depending on the percentage of carbon, ferrous metals are classified as:

Ferrous metals	Properties	Uses
Pure iron	Greyish white colour. Good magnetic properties. Disadvantages: only melts at high temperatures; difficult to machine; fragile and brittle.	Rarely used. Used in electronics and electrical components.
Cast iron	Very hard and resistant.	Machine parts, casing for engines, stands for machines, pistons, street lamps, drain covers ...
Steel	Very hard and resistant. Very resistant to traction. Easy to weld. Alloys with chrome and nickel to make stainless steel.	Structures in construction, car chassis, boats, trains, machinery, tools, screws, domestic appliances, kitchen utensils, taps ...

Pure iron is used in electronics and electrical components. It has good magnetic properties, a high melting point and is fragile and brittle.
Cast iron is used for machinery, mainly because it is very hard and resistant.
Steel is the most widely-used metal in industry and construction, and in machinery and transport because it is very hard, tough and resistant to traction.
Stainless steel is made by adding chrome and nickel to steel.

The steel-making process includes the following stages:

Iron mineral is washed to eliminate any impurities.
It is crushed and sieved to separate the gangue from the ore.
The ore is mixed with coke and limestone, and then put into a blast furnace with temperatures of over 1500°C.
Slag is obtained. This is a by-product made up of carbon and other impurities.
The pig iron is taken to a converter to:

reduce the percentage of carbon.
eliminate impurities.
adjust the composition of the steel by adding other elements such as nickel or chrome.

To improve the mechanical properties of steel, it undergoes different thermal processes.

Look for information about wrought iron and how it’s made. Then, find three examples of what it’s used for.

Apart from iron, the river water contains other metals. Find out which ones.

Río Tinto, Huelva

Find out about the different minerals in iron. Complete the following table:

Find out where there are steelworks in Spain. Give some reasons for their location.

The tools we use to cut metal are usually made of steel, which includes some chrome in its composition. Why is that?

Find out when the first furnaces in history were made. How were they constructed?

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