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  • What happens to aluminum in the recycling process?

    Aluminium recycling is not new.   Aluminium recycling is the process by which scrap aluminum can be reused in products after its initial production.  It has been a common practice since the early 1900s and extensively capitalized during World War II.    It was, however, a low-profile activity until the late 1960s when the exploding popularity of aluminium beverage cans finally placed recycling into the public consciousness.

    The process involves  re-melting the metal.  This is far less expensive and energy intensive than creating new aluminium through the electrolysis of aluminium oxide (Al2O3), which must first be mined from bauxite ore and then refined using the Bayer process. Since recycling does not transmute the element, aluminium can be recycled indefinitely and still be used to produce any product for which new aluminium could have been used.

    Recycling aluminium uses about 5% of the energy required to create aluminium from bauxite.

    The recycling of aluminium  produces significant cost savings over the production of new aluminium ….even when the cost of collection, separation and recycling are taken into account.   Over the long term, even larger national savings are made when the reduction in the capital costs associated with landfills, mines and international shipping of raw aluminium are considered.  Recycling aluminium uses about 5% of the energy required to create aluminium from bauxite. 

    For this reason, approximately 31% of all aluminium produced in the United States comes from recycled scrap.  The amount of energy required to convert aluminium oxide into aluminium can be vividly seen when the process is reversed during the combustion of thermite or ammonium perchlorate composite propellant.

    Used beverage containers are the largest component of processed aluminum scrap, with most UBC scrap manufactured back into aluminum cans.  Other sources for recycled aluminium include aircraft, automobiles, bicycles, boats, computers, cookware, gutters, siding, wire, and many other products that need a strong light weight material, or a material with high thermal conductivity.

    After collection, the scrap aluminium is separated into a range of categories such as  irony aluminium (engine blocks etc.), clean aluminium (alloy wheels) and then cleaned in preparation for the next step.  Tthe specification of the required ingot casting it will determine on the type of scrap used in the start melt.  The scrap is then taken to a reverberatory furnace (other methods appear to be either less economical and/ or dangerous) and melted down to form a “bath”.  The re-melt process removes any coatings or nk that may be present on the aluminum.  The molten metal is tested using spectroscopy on a sample taken from the melt to determine what refinements are needed to produce the final casts.   After any necessary refinements have been added the melt may be tested several times to be able to fine tune the batch to the specific standard

    Once the”recipe” of metal is correct, the furnace is tapped and poured into ingot moulds, usually via a casting machine. The melt is then left to cool, stacked and sold on as cast silicon aluminium ingot to various industries for re-use.

    There is also a secondary recycling process for aluminum.   White dross from primary aluminium production and from secondary recycling operations still contains useful quantities of aluminium which can be extracted industrially.  The process produces aluminium billets, together with a highly complex waste material.  This is a difficult to manage waste because it reacts with water, releasing a mixture of gases (including, among others, hydrogen, acetylene, and ammonia) which spontaneously ignite on contact with air.   Contact with damp air results in the release of large quantities of ammonia gas. Despite these difficulties, the waste has found use as a filler in asphalt and concrete.

     

     

    Of course there are creative ways to recycle also.  Check out what some people have done to make good use of their aluminum.CERT-34104 aluminum recycling rim table bike wheel trellis

     

    Aluminum is an amazing metal!