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Extraction of iron

Done by: Goh Cheng YenG10 Amber

How??

Iron can be obtained by reduction of iron ore in a blast furnace.

Three substances are needed: Iron ore, haematite (Fe2O3).

Limestone(calcium carbonate). Coke- mainly carbon.

The combined mixture of these three is called charge.

Blast furnace

A furnace is normally a steel tower 30 meters high.

The charge is place into the furnace.

And a series of reaction happens.

Hot air is sent into through the holes near the bottom of the furnace.

Role of coke

The coke is burnt in the base of the furnace (around 1900oC) to form carbon dioxide.

Carbon dioxide produced rises and reacts with more coke.

Formation of iron

Iron ore is reduced by carbon monoxide to from molten iron.

Note: This is a reduction reaction.

Role of limestone

The iron ore contains a major impurity, sand, silica(SiO2 ).

Limestone is used to remove this impurity from the iron ore.

The limestone decomposes first to form lime.

Then reacts with the silica to form calcium silicate.

The calcium silicate produced is also called slag,

The molten iron and molten slag flows down to the bottom of the furnace.

The slag and the iron doesn’t mix as the slag is less dense and forms on top.

The slag can be used to make roads.

End result

Summary

Uses of iron made by blast furnace

The iron produced from blast furnace is called “Pig iron” or “Cast iron”.

Contains 4% carbon and other impurities.

The carbon makes the iron brittle thus limiting its usefulness.

Most of them are used for steel making.

Environmental and health issues

Air pollutants Sulphur dioxide, nitrogen dioxide, carbon monoxide

and carbon dioxide. Steel making industry is a major carbon dioxide

releasing source causing greenhouse effect.

Waste water contamination Oil, grease, heavy metal and suspended solid.

Solid waste Coal, coke dust.

Future

Nowadays, more energy and material saving technologies are being produced.

More waste from the blast furnace is being recycled.

Organizations such as the UNEP, United Nation Environment Programme and the IISI, the first international industry association devoted to a single industry are working hard to tackle these problems.

Waste generated and recycled in steel

production in Japan

APABlast furnace. 2013. Retrieved from

http://www.s-cool.co.uk/gcse/chemistry/extraction-of-metals/revise-it/the-blast-furnace

Richard Harwood and Ian Lodge. 2010. Cambridge IGCSE Chemistry Coursebook. UK: Cambridge University Press

Spiegel, Jerry. 2011. Environmental and health issue. Retrieved from

http://www.ilo.org/oshenc/part-xi/iron-and-steel/item/593-environmental-and-public-health-issues