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Topic: The good and the bad about recycled aluminum

This is an article from the blog www.anodizingworld.com

Aluminum can either be produced from bauxite, as seen in the drawing or from aluminum scrap.

When aluminum is produced from bauxite is it called primary aluminum and from aluminum scrap, secondary aluminum.

Refinement of bauxite is sufficiently expensive and uses a lot of energy so that the secondary aluminum production is important in the global sustainable market. About 40% of aluminum in the US is recovered for secondary refining (US EPA).

The energy used to produce aluminum from aluminum scrap is 5% of the energy used for production of primary aluminum.

At the same time recycled aluminium is in no way inferior to the primary aluminium. The composition of a specific alloy is the same regardless of whether it has been produced from primary aluminium or secondary aluminium or a mixture of both.

The recycling of aluminum processes different forms of aluminum scrap, new scrap and old scrap.

New scrap (or process scrap) is the term used to describe the aluminium scrap produced during the manufacture and fabrication of aluminium alloys until such a time as the products are sold to the end-user.

Old scrap (or used scrap) is recovered from used end-products and aluminium components.

The main environmental issue when recycling of aluminum is the air pollution. When remelting used aluminum scrap a flux layer is necessary to cover the aluminum melt from exposure of the oxygen in the air.

From EPA news, released date 08/04/2009, the Aluminum Recyclers have agreed to implement new environmental improvements and controls. Aleris International Inc., is one of US largest aluminum recyclers, and 13 of its subsidiaries have committed to implementing environmental improvements and controls projected to cost $4.2 million at 15 plants located in 11 states, U.S. Environmental Protection Agency (EPA) and the Justice Department announced today.

From Aleris International Inc. website I found this quote, so did you know that?

Aluminum recycling is easy to do, and it makes a difference to the planet. Recycling a single aluminum can save enough energy to light a light bulb for four hours or to operate a television for three hours.

A lot of the information below is found on Alu-Scout, Aluminium on the net.

The aluminum scrap has to be sorted into type and size using various techniques (magnetic sorting and eddy current sorting, flotation, testing, etc.). Depending on the quality and the amount of impurities in the form of other materials, such as coatings, paint, oil, etc., coatings are subsequently removed from the scrap.

A so-called two-chamber process is used to remelt lacquered scrap. The lacquer is stripped thermally in the first chamber and the scrap then enters the melting furnace. This is not the case with anodized scrap. The aluminum oxide will be found in the dross, which comprises of the cover flux, impurities and metal oxides and can be recovered from this dross afterwards.

Depending on the quality of the molten metal, it may be necessary to carry out an additional step, namely refining. This usually takes place in a holding furnace, in which the melt is cleaned and the desired alloy is achieved by the addition of alloying elements or the removal of impurities.

Most scrap is processed to ingots, which are subsequently processed to produce high-quality aluminum castings. As ever-more sophisticated techniques become available, a larger fraction of the scrap is uniform or well sorted. This makes it possible to produce wrought alloys, extrusion ingots and rolling ingots.

Some people think that secondary aluminum is more difficult to surface finish but this is absolutely not true. The secondary aluminum with a specific composition of the alloy following the specification for the alloy, is as good as primary aluminum for anodizing and other surface finishes.

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Sunny regards

Anne


www.anodizingworld.com

skip

Re: The good and the bad about recycled aluminum

First let me preface my random commits by saying;

For me no global warming is possible. Only two sources of energy on earth are the sun and nuclear. Say just for giggles one huge solar panel was needed to power the U.S. This panel would need to cover all of Spain. Turning all of Spain under this solar panel into a permafrost, endless and lifeless wasteland. Of course another solar panel the same size would be needed 180 degrees around the globe for power when night befalls Spain. Plus long electrical extension cords of fiber optics. "Ain't gonna happen."

California is a desert, always was, always will be. Want water? Build nuclear power plants to power 100+ foot~head pumps and squeeze the ocean through some membranes for fresh water. And since the land West of the Mississippi River is up hill from the land East of the Mississippi River not enough electric power can be found to pump and push the east coast water to the west coast's need.

The sun evaporates water and makes rain fall, makes the barometer move and wind blow, makes algae bloom and store btu's, makes plants synthesize light. 'C', in, 'O' out. Where does the 'C' stay? In the plants. Cap and Trade my butt Mr. Al Gore.

Nuclear heat in the core of the globe makes the Old Faithful gusher, faithful. Some 13 foot of sea water is equal to one foot of lead shielding. Admiral Rickover's NR-1 submarine used seawater astern of the nuclear 'kettle' and 1 foot of lead forward where 100% of the crew was stationed. Woods Hole now sails the NR-1.

For me no energy sources are renewable. Alternatives yes. Renewable no. Entropy is the opposite of energy. Entropy is what everything with energy in it, turns into. It is not possible to renew or add energy into 'something' without putting more energy into that 'something' then was taken out.

For me more costly alternative sources can be had. How many more electric power plants would be needed if cars were electric? Two identical cars. One gasoline engine. One electric motor. Both cars require the same exact btu's to cruise down the road at the same speed. The btu difference is the efficiency between a engine and a motor. Waste heat. But an electric generating powerplant is still needed for the motor. Oh I forgot Fan Laws. Resistance through the air squares as speed doubles. Slow down. Drive like you have a raw egg between the gas pedal and your foot. Ever notice the driver in front of you is a moron and the driver passing you is a maniac? Why don't motors [full torque at anything above zero rpm's.] have multispeed transmissions while engines do. Why not multispeed transmissions on yachts?

Some very weird things-->I heard but have no idea if these are true.

Out the Stack:

The U.S.A. has a small number [maybe 5?] steel mills limping along at a reduced tonnage, cold blast furnaces, and a huge 'brain drain' and over all regulated out of business but with clean stack emissions.

China around 2,800 steel mills humming along at a high rate of tonnage without regulation and dirty stacks and a ton of workers enhanced by the whole trickle down effect thing.

India has 3 steel mills, unregulated, well oiled with workers and cash, and out producing all that China rolls out.

Over The Side:

Subaru is owned by Fuji Heavy Industries that have behemoth sized factory ships that travel to Australia, load the sand/bauxite off the beach and once in international waters, fire up the propane fired smelters and pricepate the aluminum out of the beach sand/bauxite, tossing the dregs over the side and freely exhausting the effluents to the atmosphere. Unregulated but very cost efficient. I also heard that Subaru moved some production from Japan, to China. That became too expensive so now moved again to Korea. Of course Subaru still assembles cars in Indiana, south of Chicago. [Indiana has lower taxes then Illinois. Whitch is why the $44 million Palmer Johnson Yachts in my town of Sturgeon Bay, Wisconsin sells and tranferrs ownership in Indiana waters, as well.]

It was interesting to note that when Toyota needed extra capacity for a short time that Subaru allowed Toyota to assemble their cars at Subaru~Indiana. Do you think GM would allow Ford to do this?

Anyone want to talk or rant about the multiplicities of life?

skip.

Last edited by skip (12/31/2009 - 08:17 AM)

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Spikky

Re: The good and the bad about recycled aluminum

The composition of a specific alloy is the same regardless of whether it has been produced from primary aluminium or secondary aluminium or a mixture of both.

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