Metal

Scrap metal originates both in business and residential environments. Typically a “scrapper” will advertise their services to conveniently remove scrap metal for people who don’t need it.

 

Scrap is often taken to a wrecking yard (also known as a scrapyard, junkyard, or breaker’s yard), where it is processed for later melting into new products. A wrecking yard, depending on its location, may allow customers to browse their lot and purchase items before they are sent to the smelters, although many scrap yards that deal in large quantities of scrap usually do not, often selling entire units such as engines or machinery by weight with no regard to their functional status. Customers are typically required to supply all of their own tools and labor to extract parts, and some scrapyards may first require waiving liability for personal injury before entering. Many scrapyards also sell bulk metals (stainless steel, etc.) by weight, often at prices substantially below the retail purchasing costs of similar pieces.

 

A scrap metal shredder is often used to recycle items containing a variety of other materials in combination with steel. Examples are automobiles and white goods such as refrigerators, stoves, clothes washers, etc. These items are labor-intensive to manually sort things like plastic, copper, aluminum, and brass. By shredding into relatively small pieces, the steel can easily be separated out magnetically. The non-ferrous waste stream requires other techniques to sort.

 

In contrast to wrecking yards, scrapyards typically sell everything by weight, instead of by item. To the scrapyard, the primary value of the scrap is what the smelter will give them for it, rather than the value of whatever shape the metal may be in. An auto wrecker, on the other hand, would price exactly the same scrap based on what the item does, regardless of what it weighs. Typically, if a wrecker cannot sell something above the value of the metal in it, they would then take it to the scrapyard and sell it by weight. Equipment containing parts of various metals can often be purchased at a price below that of either of the metals, due to saving the scrapyard the labor of separating the metals before shipping them to be recycled.

 

According to research conducted by the US Environmental Protection Agency, recycling scrap metals can be quite beneficial to the environment. Using recycled scrap metal in place of virgin iron ore can yield:

75%

savings in energy.

90%

savings in raw materials used.

86%

reduction in air pollution.

40%

reduction in water use.

76%

reduction in water pollution.

97%

reduction in mining wastes.

Every ton of new steel made from scrap steel saves:

  • 1,115 kg of iron ore.
  • 625 kg of coal.
  • 53 kg of limestone.

Energy savings from other metals include:

  • Aluminium savings of 95% energy.
  • Copper savings of 85% energy.
  • Lead savings of 65% energy.
  • Zinc savings of 60% energy.

The metal recycling industry encompasses a wide range of metals. The more frequently recycled metals are scrap steel, iron (ISS), lead, aluminium, copper, stainless steel and zinc. There are two main categories of metals: ferrous and non-ferrous. Metals which contain iron in them are known as ferrous.

Metals without iron are non-ferrous.

 

Common non-ferrous metals are copper, brass, aluminum, zinc, magnesium, tin, nickel, and lead.

 

Usable coins can be deposited in banks. Damaged US coins can be redeemed for money via the Mutilated Coin Redemption Program.

 

Non-ferrous metals also include precious and exotic metals:

 

Precious metals are metals with a high market value in any form, such as gold, silver, and platinum group metals.

 

Exotic metals contain rare elements such as cobalt, mercury, titanium, tungsten, arsenic, beryllium, bismuth, cerium, cadmium, niobium, indium, gallium, germanium, lithium, selenium, tantalum, tellurium, vanadium, and zirconium. Some types of metals are radioactive. These may be “naturally occurring” or formed by nuclear reactions. Metals that have been exposed to radioactive sources may also become radioactive in settings such as medical environments, research laboratories, and nuclear power plants.

 

OSHA guidelines should be followed when recycling any type of scrap metal to ensure safety.

 

Aluminium recycling is the process by which scrap aluminium can be reused in products after its initial production. The process involves simply re-melting the metal, which 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. Recycling scrap aluminium requires only 5% of the energy used to make new aluminium from the raw ore. For this reason, approximately 36% of all aluminium produced in the United States comes from old recycled scrap. Used beverage containers are the largest component of processed aluminum scrap, and most of it is manufactured back into aluminium cans.

Process for beverage cans

 

Aluminium beverage cans are usually recycled by the following method:

 

Cans are first divided from municipal waste, usually through an eddy current separator, and cut into small, equally sized pieces to lessen the volume and make it easier for the machines that separate them.

 

Pieces are cleaned chemically/mechanically and blocked to minimize oxidation losses when melted. (The surface of aluminium readily oxidizes back into aluminium oxide when exposed to oxygen.[11])

 

Blocks are loaded into the furnace and heated to 750 °C ± 100 °C to produce molten aluminium.

 

Dross is removed, and the dissolved hydrogen is degassed. (Molten aluminium readily disassociates hydrogen from water vapor and hydrocarbon contaminants.) This is typically done with chlorine and nitrogen gas. Hexachloroethane tablets are normally used as the source for chlorine. Ammonium perchlorate can also be used, as it decomposes mainly into chlorine, nitrogen, and oxygen when heated.

 

Samples are taken for spectroscopic analysis. Depending on the final product desired, high-purity aluminium, copper, zinc, manganese, silicon, and/or magnesium is added to alter the molten composition to the proper alloy specification. The top-five aluminium alloys produced are 6061, 7075, 1100, 6063, and 2024.