Zinc is the 30th element on the periodic table. It is a silvery-white metal that tarnishes in air, and has many uses in society. Zinc is the 4th most common metal in use, next to iron, aluminum and copper.
Over 13 million tonnes of zinc are produced worldwide each year, primarily in China, Australia, and Peru. Considering the embodied energy in zinc production is, on average, between 49-55 MJ/kg, this puts the total annual energy required to produce zinc between 637-715 petajoules (1015 joules).
Some useful properties of zinc include:
|Density (at 0oC)||7.134 g/cm3|
|Boiling point||1180 K|
|Melting point||692.68 K|
|Embodied energy||49-55 MJ/kg|
Roughly a third of all zinc is used to galvanize other metals - this means it protects the metal from rusting. An object such as an iron nail is protected from corrosion by giving it a protective layer of zinc. Galvanized steel is used for car bodies, street lamp posts, and suspension bridges.
Zinc is also used to make useful alloys such as brass, where it is mixed with up to 95% copper. Brass is a very common alloy, and was used more than 2500 years ago by the Ancient Romans. Today, brass is used to make musical instruments, screws and other hardware. Zinc is also alloyed with lead and tin to make solder, used in joining electrical pieces together such as pairs of copper wire.
Zinc is essential for life, as it forms the site for over 20 metallo-enzymes. The average human contains around 2.5 grams of zinc at any one time, and intakes around 15 milligrams per day from foods such as beef, lamb, or cheese.
Too much zinc is dangerous however, as it can be carcinogenic in excess.