This is the VOA Special English Development Report.
People have been recycling metals for hundreds of years.
Today, re-using metal waste or scrap provides work for many people, especially
in developing countries. Three kinds of metals are recycled. They are ferrous metals, non-ferrous metals and
precious metals
.
Ferrous metals contain iron. They are low in cost and
recycled in large amounts. Metallic iron called pig iron is produced when
iron is heated in a hot industrial stove. This kind of stove is called a blast furnace. Pig iron
contains another element, carbon. Pig iron is useful because it can be formed
into solid, heavy objects or objects with unusual shapes.
Another kind
of iron is steel, which is iron without the carbon. Making steel is simply
removing the carbon by burning it away. This makes the steel stronger and easier
to cut than iron. Both pig iron and steel waste or scrap are useful because they
can be melted to make new products.
In countries where there is a shortage of steel scrap, old tin cans are
sometimes used. Tin cans are mostly steel. They can be melted. If the scrap is
heated before the temperature gets to the melting point, the blast furnace can
be more simply designed and less costly. These simpler furnaces are called
foundries. Products are made in foundries all over the world, but especially in
Asia.
Non-ferrous metals include copper and aluminum. Copper is the perfect
material for recycling. It is valuable, easy to identify and easy to clean.
People who operate foundries around the world buy copper wire and cable to
recycle.
Aluminum is another very popular non-ferrous scrap metal. It is cheap to
produce and very easy to work with. In developing countries, small foundries
produce aluminum bars, sheets and wire.
Precious metals like silver also are recycled. Silver can be found in
pictures made with old cameras. And it can be found in X-rays after they have
been developed. X-ray film is very valuable for recycling silver, because both
sides of the film are usually developed.
And that's the VOA Special English Development Report. You can learn more
about recycling metals through VITA, Volunteers in Technical Assistance. VITA is
on the Web at enterpriseworks.org. And Internet users can find transcripts and
archives of all of our reports at voaspecialenglish.com. This is Shep O'Neal.
ferrous metal :黑色金屬
precious
metal :貴金屬
blast
furnace :鼓風爐
pig iron :生鐵
（來源：VOA 英語點津姍姍編輯）
