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Scrap-Metal Separation May Become Cheaper
According to the Environmental Protection Agency, the United States throws 14.8 million tons of scrap metal into landfills every year. One of the main reasons is the difficulty of large-scale separation of non-ferrous metals. Scientists at the University of Utah now say they have solved that problem.
Recycling metals is much cheaper than extracting them from the ore. But chopping up old cars, appliances or industrial equipment results in a mixture of different metal parts.
Iron and steel are easily separated with strong magnets, while others, such as copper, aluminum and titanium, either end up in landfills or are shipped to countries with cheap labor to pick out the different metal by hand.
Researchers at the University of Utah now say they have developed a method for mechanically separating light metals with high degree of accuracy.
Don Eggert of O2M Technologies, which partnered with the school in developing the technology, said the system is based on the fact that all metals react to a strong magnetic field.
“When the metal falls through the field, even it’s non-ferrous, it’s not attracted to the magnet, but the magnet causes there to be an electric current inside the metal and that causes the metal to have a magnetic field itself, which interacts with the magnetic field that it’s falling through and pushes it to the side,” said Eggert.
Eggert said rapid change in the frequency of the magnetic field results in metal pieces falling into different bins.
“So, for example, if we want to separate aluminum and copper we hit the right frequency for it and the aluminum would push more away from the magnet than the copper will," he said. "So the copper falls straight down, the aluminum falls into a different bucket.”
This is just one of the technologies for separating different metals but Eggert says it is much cheaper to build since it requires only one large circular magnet and a frequency controller.
“What we have calculated so far is that the expense to value ratio -- that is how quickly you can pay back the cost of the technology over time - we’re currently estimating it to be less than one year.”
At the moment, the separator works only with pellets up to one centimeter wide. Researchers are now building a bigger magnet with a wider cut to accommodate larger metal parts. They hope to have it installed at a metal shredding facility sometime this year, where they will be able to test it in a real-life environment.
詞匯解析
swallow
難度：3星常用詞匯，屬常用6000詞
英漢解釋
n.燕子；吞咽；一次吞咽的量
v.忍受；吞下；咽下；輕信；不流露感情；收回
參考例句
用作名詞 (n.)
There are many swallows flying in the sky.
天空中有許多燕子。
1用作動(dòng)詞 (v.)
They can't treat me like that; I'm not going to swallow it.
他們不能這樣對待我，我忍不下這口氣。
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identify
難度：4星核心詞匯，屬常用3000詞
英漢解釋
vt.鑒定；識(shí)別，辨認(rèn)出，認(rèn)出；認(rèn)明；把…看成一樣
vi.認(rèn)同；感同身受
參考例句
用作及物動(dòng)詞 (vt.)
The test can identify the presence of abnormalities in the unborn child.
這項(xiàng)化驗(yàn)?zāi)荑b定胎兒是否有不正常現(xiàn)象。
用作不及物動(dòng)詞 (vi.)
I identified with the heroine of the novel.
我與小說中的那個(gè)女主人公感同身受。
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poverty
難度：4星核心詞匯，屬常用3000詞
英漢解釋
n.貧困；貧乏；劣質(zhì)
參考例句
用作名詞 (n.)
They were handicapped by (a) poverty of resources.
他們因資源短缺處境窘迫。
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repeatedly
難度：2星擴(kuò)展詞匯，屬常用10000詞
英漢解釋
adv.重復(fù)地；再三地
參考例句
用作副詞 (adv.)
He drew a long breath and repeatedly chanted the name of Rama, every word showering nectar into the hearts of the devotees.
他深深地吸了一口氣，重復(fù)地唱頌著羅摩的名字，每一個(gè)字都像甘露般地灑落在奉獻(xiàn)者的心里。
B. However, in order to restore peace and social order, individual states or the international community has repeatedly used force in history.
然而，歷史上為了恢復(fù)和平和社會(huì)秩序，個(gè)別的國家或國際社會(huì)再三地使用武力。
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rescue
難度：4星核心詞匯，屬常用3000詞
英漢解釋
vt.營救；援救
n.營救；救援
參考例句
用作及物動(dòng)詞 (vt.)
The government has rescued the firm from bankruptcy by giving them a grant.
政府撥款給這家公司使其免于破產(chǎn)。
用作名詞 (n.)
Rescue workers rushed to the site of the plane crash.
搶救人員沖向飛機(jī)墜毀的現(xiàn)常
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restrict
難度：4星核心詞匯，屬常用3000詞
英漢解釋
vt.限制；約束
參考例句
用作及物動(dòng)詞 (vt.)
In a move to restrict imports, the government raised custom duties.
政府在限制進(jìn)口的措施中提高了關(guān)稅。
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approve
難度：4星核心詞匯，屬常用3000詞
英漢解釋
v.批準(zhǔn)；贊成；同意；稱許
參考例句
用作動(dòng)詞 (v.)
I approve of your trying to earn some money, but please don't neglect your studies.
我同意你去掙一些錢，可是請不要誤了功課。
No teacher can approve of cheating in exams.
任何教師都不能允許考試作弊。
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