官方APP下载:英语全能特训(微信小程序版,支持苹果手机、安卓手机)
创办于2003年
UNSV记不住?那就记中文谐音“忧安思危”吧!
  Slow and Steady Wins the Race!
UNSV英语学习频道 - Slow and steady wins the race!
公众微信服务号
英语全能特训(微信公众服务号)
UNSV英语学习频道淘宝网店
客服短信:18913948480
客服邮箱:web@unsv.com
初级VIP会员
全站英语学习资料下载。
¥98元/12个月

DEVELOPMENT REPORT - Recycling Scrap Metal

阅读次数:


VIP会员专享下载:(非VIP会员无权下载!如果想下载,但还不是VIP会员,请点此订购
下载方式:使用鼠标右键(注意是鼠标右键!)点击下面的MP3音频/MP4视频链接,然后选择“另存为…”。
PDF节目文稿 PDF节目文稿  MP3节目录音 MP3节目录音 
文章正文
同步字幕

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.

Graphic Image
Graphic Image

Ferrous metals contain iron. They are low in cost and recycled in huge 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 also 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 and melted. Tin cans are mostly steel. 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 an old black-and-white camera. 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.

You can learn more about recycling metals from Volunteers in Technical Assistance, or VITA. VITA is on the Internet at vita.org.

This VOA Special English Development Report was written by Gary Garriott.

网友的学习评论(0条):
版权所有©2003-2019 南京通享科技有限公司,保留所有权利。未经书面许可,严禁转载本站内容,违者追究法律责任。 互联网经营ICP证:苏B2-20120186
网站备案:苏ICP备05000269号-1中国工业和信息化部网站备案查询
广播台