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Saturday, November 23, 2013

Aluminium: The metal that just keeps on giving

Two hundred years ago, no-one knew aluminium existed. Today it is everywhere - in cans, window frames, packaging, even car bodies. New uses for it are constantly being discovered - but it's possible that one day we'll be able to stop mining the ore, and rely completely on recycling.

crushed aluminium cans
A couple of months from now you could be driving these around on the streets

Aluminium has a split personality.
It may look dull, but it is one of the most reactive metals in the periodic table.
"Aluminium fires are quite terrifying," says Andrea Sella, chemistry professor at University College London.
"When you take aluminium and you burn it, you get a very, very intense fire."
From that point of view, it may not be ideal for aircraft construction - but this disadvantage is outweighed by its strength, flexibility and exceptional lightness.
The soft, malleable metal's alter ego is aluminium oxide, which forms a skin on the pure metal the moment it is exposed to air (and makes it unlikely that an aircraft will catch fire).
This oxide is so hard that it is used to make sandpaper and other abrasive materials.

Aluminium - key facts

Aluminium - symbol, atomic number and weight
  • Soft, non-magnetic metal
  • Symbol: Al
  • Atomic number: 13
  • Weight: 26.98
  • 3rd most abundant element in Earth's crust after oxygen and silicon
  • Found mainly as bauxite
  • Yearly primary aluminium production: 53.4m tonnes
  • Increasingly recycled
  • Used in transport, packaging, construction and household goods
Among gemstones, sapphires - crystals formed from the oxide - are second only to diamonds in their hardness.
Indeed, there is a growing industry for manufacturing industrial sapphires the size of a large bucket, suitable for use in bullet-proof glass, aeroplane windows and soon -unscratchable smartphone displays.
Although Aluminium is the third most abundant element in the earth's crust, it was not isolated until 1825, and remained so scarce that it was valued more highly than silver for decades.
The reason it remained hidden for so long, unlike gold or silver, is that it is too reactive to be occur in its pure form.
Instead it is found as bauxite, a reddish-brown ore named after the French town Les Baux, where it was first discovered.
Bauxite is found across the globe, and mining it is the easy part. Far trickier is extracting the metal. It was not until 1886 that a Frenchman and an American both cracked it.
Bauxite is processed at the Compagnie des Bauxites de Guinee  factory, Kamsar, Guinea Bauxite is mined all over the world, from Australia to Brazil to India to Guinea
You have to melt the bauxite in another mineral called cryolite, and then pass an electric current through it, separating the oxygen atoms from the aluminium. It takes four tonnes of bauxite to produce one tonne of aluminium.
The process is highly energy-intensive and therefore expensive.

Baked sapphire

Freshly baked industrial sapphire
  • Naturally-occurring sapphires can take 50,000 years to form
  • Now they can be baked in a week, in ovens made of molybdenum and tungsten - which unlike steel do not melt at 2,200C
  • A sapphire hard drive is reported to have been developed that can store information on nuclear waste dumps for up to a million years - enough time for safe radioactive decay
But recycling aluminium uses a fraction of the energy.
"Beverage cans get recycled within 60 days, so a can of soda is back on the shelves 60 days later," says Nick Madden, who is responsible for buying raw metal for Novelis, the world's biggest manufacturer of rolled aluminium sheets.
Once you have the metal, you can re-use it again and again, almost indefinitely.
"It is one of the few materials that is genuinely 100% recyclable," Madden says.
In theory, a day may come when we have mined all we need, and we can just keep re-using what we already have.
"If demand stops growing, and scrap comes back from older uses like buildings in the future, then that will start to reduce the required primary consumption," says Madden.
For now, though, demand is growing, and carmakers are one reason why. Lighter car bodies mean more fuel efficiency, better acceleration and braking, and lower carbon emissions.
Range Rover car bodies and workers at Jaguar Land Rover, Solihull, UK A new aluminium Range Rover in the making - minus the family
Novelis has seen a 25% increase in demand from the motor industry in the last year, most of it coming from one of its biggest customers, Jaguar Land Rover, which has just begun manufacturing Range Rovers with aluminium.

The new car uses use 25% less fuel partly because its body is 39% lighter, helping to reduce the car's total weight by 420kg (925lb).
"That's the equivalent of five people," says Nick Rogers, the Range Rover vehicle line director.
"So, if you imagine driving around with all your family in the car - you feel the weight of the vehicle.
"When you get in the new Range Rover Sport, all of your family has gone."
Currently, Novelis obtains almost 50% of its aluminium used to make a new Range Rover from junk - empty cans, scrapped vehicles, demolition sites - and it aims to raise that to 80% by 2020.
One challenge is to ensure that more aluminium finds its way into the recycling loop.
"In the UK, I believe the recycle rate [of household aluminium waste] is about 75%," Madden says.
Whether bauxite mining is still needed in our grandchildren's day may depend on the proportion we succeed in recycling, and whether we keep coming up with new uses for aluminium - either the light, malleable metal, or the hard almost unscratchable sapphire.

From BBC news


Endangered pangolins rescued in Thailand

Pangolin

More than 100 endangered pangolins have been rescued by customs officials in Thailand, south-east Asia


The unusual looking scaly creatures, which eat ants and termites, were found in boxes on the back of a car.
It's thought they were being smuggled in from neighbouring Malaysia.
The pangolins are recovering at a national park until they're ready to be taken back to the wild.

From CBBC newsround

Sunday, November 17, 2013

Charity blames climate change for Typhoon Haiyan

Charity workers have called on world leaders to do more to tackle climate change, because they say events like Typhoon Haiyan could be caused by it.
Family stands among rubble in the Philippines


The UK Disasters Emergency Committee (DEC), which is made up of 14 UK charities, say Typhoon Haiyan is an example of the sort of weather that could happen more often if the world doesn't take action.
But not all scientists agree that extreme weather events are caused by man-made climate change.

UN meeting

The United Nations, a joint committee of governments from across the world, are currently holding climate talks in Warsaw in Poland. The group is discussing ways to get countries to lower their carbon footprint.
Recent reports from the UN suggest human activities are causing a rise in gases that cause global warming. Some climate experts say this results in a change in weather and environment.
So the DEC has called on the UN to use this meeting to discuss events like Typhoon Haiyan and take action to tackle it.
But not everyone agrees that extreme weather like Typhoon Haiyan happen because of a rise in gases caused by human activities.
From CBBC Newsround

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