question: How are giant piles of random shredded metal scrap recycled? Do they have a way to separate the different types of metal? Or can a random hodgepodge of metal be melted down and still be useful?
comment: There are several methods for sorting out the different metals. Some you can easily do yourself and some are best left to the pros. The most basic would be to separate ferrous and non-ferrous metals using a magnet. The magnet sticks to ferrous metals like iron, and not to non-ferrous like alluminum. Further sorting your non-ferrous can be largely done by color and density (yellow = brass, silver and lightweight=aluminum, heavy and grey=lead, etc.). Going any further gets more complicated. Especially when dealing with alloys or mixed metals. Some can be separated by melting them down and letting the metals separate by density, others need chemical treatments to dissolve one metal and not another, and some simply can't be separated at all.
passages: BULLET::::- There is almost always some money to be made from the stream of recycled chips, whether by the scrap processor, the machine shop, or often both. The scrap value (melt value) of the metal is a net gain beyond any costs of handling and transporting the chips.
  
  Section::::Recycling.:Requirements.
  
  Machine shops are typically required by the scrap collector to: 
  
  BULLET::::- segregate metal types (e.g., aluminum chips in separate barrels from steel chips)
  
  BULLET::::- it is usually "not" required to segregate particular alloys (e.g., to keep 2024 aluminum separate from 6061)
   Due to their extensive use, non-ferrous scrap metals are usually recycled. The secondary materials in scrap are vital to the metallurgy industry, as the production of new metals often needs them. Some recycling facilities re-smelt and recast non-ferrous materials; the dross is collected and stored onsite while the metal fumes are filtered and collected. Non-ferrous scrap metals are sourced from industrial scrap materials, particle emissions and obsolete technology (for example, copper cables) scrap.
  
  Section::::Ancient history.
   Iron and steel are the world's most recycled materials, and among the easiest materials to reprocess, as they can be separated magnetically from the waste stream. Recycling is via a steelworks: scrap is either remelted in an electric arc furnace (90-100% scrap), or used as part of the charge in a Basic Oxygen Furnace (around 25% scrap). Any grade of steel can be recycled to top quality new metal, with no 'downgrading' from prime to lower quality materials as steel is recycled repeatedly. 42% of crude steel produced is recycled material.
  
  Section::::Metals.:Other metals.
  
  For information about recycling other, less common metals, refer to:
   A wide range of metals in commercial and domestic use have well developed recycling markets in most developed countries. Domestic recycling is commonly available for Iron and steel, aluminium and in particular beverage and food cans. In addition, building metals such as copper, zinc and lead are readily recyclable through specialised companies. In the UK, these are usually either specialised scrap dealers or car breakers. Other metals present in smaller quantities in the domestic waste stream such as tin and chromium are also extracted from metal put into the recycling system but are rarely recovered from the general waste stream.
   Batteries and copper are sorted out first for quality control purposes. The materials are then compacted. Next, iron and steel (ferrous metals) are extracted using electromagnets. They are collected and made ready for sale. Then metals are separated from non-metals using eddy currents. Eddy currents are created by rapidly alternating magnetic fields, which induce metals to jump away from non-metals. Then water separation is used to sort plastics and glass from circuit boards and copper wires. Circuit boards and copper content is then sold. Plastics and glass are further compacted for reuse.
  
  Section::::Recycling By Region.
   The process of recycling copper is roughly the same as is used to extract copper but requires fewer steps. High-purity scrap copper is melted in a furnace and then reduced and cast into billets and ingots; lower-purity scrap is refined by electroplating in a bath of sulfuric acid.
  
  Section::::Alloys.
   The sorting component of the plants typically resemble a materials recovery facility. This component is either configured to recover the individual elements of the waste or produce a refuse-derived fuel that can be used for the generation of power.
  
  The components of the mixed waste stream that can be recovered include:
  
  BULLET::::- Ferrous metal
  
  BULLET::::- Non-ferrous metal
  
  BULLET::::- Plastic
  
  BULLET::::- Glass
  
  Section::::Terminology.
   Section::::Divisions.
  
  Section::::Divisions.:Metals Recycling.
  
  Sims Metal Management buys ferrous metal from metal dealers, peddlers, auto wreckers, demolition firms and others who generate obsolete metal and from manufacturers who generate industrial metal. Ferrous metal is processed for resale using a variety of methods, including sorting, shredding, cutting, torching, baling or breaking. After processing, ferrous recycled metal is sold to end users such as EAF mills, integrated steel mill, foundaires and brokers.
   Section::::Ferrous metal recycling.:Types of scrap used in steelmaking.
  
  BULLET::::- Heavy melting steel – Industrial or commercial scrap steel greater than 6 mm thick, such as plates, beams, columns, channels; may also include scrap machinery or implements or certain metal stampings
  
  BULLET::::- Old car bodies – Vehicles with or without interiors and their original wheels
  
  BULLET::::- Cast iron – Cast iron bathtubs, machinery, pipe, and engine blocks
  
  BULLET::::- Pressing steel – Domestic scrap metal up to approx. thick. Examples - "White goods" (fridges, washing machines, etc.), roofing iron, water heaters, water tanks, and sheet metal offcuts
   Section::::Operation.
  
  Scrap metal is delivered to a scrap bay, located next to the melt shop. Scrap generally comes in two main grades: shred (whitegoods, cars and other objects made of similar light-gauge steel) and heavy melt (large slabs and beams), along with some direct reduced iron (DRI) or pig iron for chemical balance. Some furnaces melt almost 100% DRI.
   Once the correct "recipe" of metal is available, 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. Mainly, cast alloys like ADC12, LM2, AlSi132, LM24 etc. are produced. These secondary alloys ingots are used in die cast companies.
  
  Tilting rotary furnaces are used for recycling of aluminium scrap, which give higher recovery compared to reverberatory furnaces (Skelner Furnace).
  
  Section::::Recycling rates.
   Metal scrap recycling, also called secondary metal processing, is a large industry that processes, in the U.S. alone, 56 million tons of scrap iron and steel (including 10 million tons of scrap automobiles), 1.5 million tons of scrap copper, 2.5 million tons of scrap aluminum, 1.3 million tons of scrap lead, 300,000 tons of scrap zinc and 800,000 tons of scrap stainless steel, and smaller quantities of other metals, on a yearly basis.
  
  Section::::Types.
   Sims is heavily focused on reducing the potential risk of fire at their scrap metal recycling facilities. In light of the stockpiled material fires which occurred in 2013 at the company’s Redwood City, California and Jersey City, New Jersey locations, Sims has considered factors such as stockpile size and the use of technology such as heat sensors.
   Depending on the specification of the required ingot casting, it will depend on the type of scrap used in the start melt. Generally, the scrap is charged to a reverberatory furnace (other methods appear to be either less economical and/or dangerous) and melted down to form a "bath". 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 the refinements have been added, the melt may be tested several times to be able to fine-tune the batch to the specific standard.
   In 2014, the NGO Pure Earth (formally Blacksmith Institute) funded the creation of a Copper Wire Recycling Center within Agbogbloshie and helped to install several automated machines to simplify the removal of plastic coating and reduce the burning. Efforts appear to be moderately successful however the burning continues.
  
  Section::::References in popular culture.
  
  BULLET::::- The official video of the Placebo cover of Talk Talk's song "Life's What You Make It" starts with "This film is dedicated to the workers of Agbogbloshie".
  
  Section::::See also.
  
  BULLET::::- Guiyu (town) (electronic waste site in China)
  
  Section::::External links.
   Ferrous metals are able to be recycled, with steel being one of the most recycled materials in the world. Ferrous metals contain an appreciable percentage of iron and the addition of carbon and other substances creates steel.
  
  Section::::Ferrous metal recycling.:Description.
   It is normal that good-quality scrap copper, such as that from a nuclear plant, is refined in one furnace before being refined further in an electrochemical process. The furnace generates impure metal, slag, dust and gases. The dust accumulates in a bag house, while the gases are vented to the atmosphere. The impure metal from the furnace may be further refined in an electrochemical process.
  
  If the copper refinery includes an electrochemical process after the furnace, then unwanted elements are removed from the impure metal and deposited as anode slime.
  
  Section::::See also.
  
  BULLET::::- Nuclear crime
  
  Section::::External links.
   Many materials used in computer hardware can be recovered by recycling for use in future production. Reuse of tin, silicon, iron, aluminium, and a variety of plastics that are present in bulk in computers or other electronics can reduce the costs of constructing new systems. Components frequently contain copper, gold, tantalum, silver, platinum, Palladium, and lead as well as other valuable materials suitable for reclamation.
   BULLET::::6. The furnace is tapped, the molten aluminium poured out, and the process is repeated again for the next batch. Depending on the end product, it may be cast into ingots, billets, or rods, formed into large slabs for rolling, atomized into powder, sent to an extruder, or transported in its molten state to manufacturing facilities for further processing.
  
  Section::::Ingot production using reverberatory furnaces.
  
  The scrap aluminium is separated into a range of categories such as irony aluminium (engine blocks etc.), clean aluminium (alloy wheels). Scraps are classified according to ISRI (Institute of Scrap Recycling Industries).
   Section::::Hazards.
  
  Great potential exists in the scrap metal industry for accidents in which a hazardous material present in scrap causes death, injury, or environmental damage. A classic example is radioactivity in scrap; the Goiânia accident and the Mayapuri radiological accident were incidents involving radioactive materials. Toxic materials such as asbestos, and toxic metals such as beryllium, cadmium, and mercury may pose dangers to personnel, as well as contaminating materials intended for metal smelters.
  
  Many specialized tools used in scrapyards are hazardous, such as the alligator shear, which cuts metal using hydraulic force, compactors, and scrap metal shredders.
  
  Section::::Benefits of recycling.
   Globally, metal recycling is generally low. In 2010, the International Resource Panel, hosted by the United Nations Environment Programme published reports on metal stocks that exist within society and their recycling rates. The authors of the report observed that the metal stocks in society can serve as huge mines above ground. They warned that the recycling rates of some rare metals used in applications such as mobile phones, battery packs for hybrid cars and fuel cells are so low that unless future end-of-life recycling rates are dramatically stepped up these critical metals will become unavailable for use in modern technology.
   Levels of metals recycling are generally low. In 2010, the International Resource Panel, hosted by the United Nations Environment Programme (UNEP) published reports on metal stocks that exist within society and their recycling rates. The Panel reported that the increase in the use of metals during the 20th and into the 21st century has led to a substantial shift in metal stocks from below ground to use in applications within society above ground. For example, the in-use stock of copper in the USA grew from 73 to 238 kg per capita between 1932 and 1999.
   BULLET::::- Scrap reporting – This can be the most difficult area to maintain with any integrity. Start with isolating the scrap by providing scrap bins at the production site and then record the scrap from the bins on a daily basis. One benefit of reviewing the scrap on site is that preventive action can be taken by the engineering group.
   Section::::Source melting.:Aluminium scrap.
  
  It is normal to place silicon, aluminium scrap and flux in a furnace. This is heated to form molten aluminium. From the furnace three main streams are obtained, metal product, dross (metal oxides and halides which are skimmed off the molten metal product) and off gases which go to the baghouse. The cooled waste gasses are then allowed out into the environment.
  
  Section::::Source melting.:Copper scrap.
   Bremen Castings foundry produces castings made from recycled materials such as plate and structural steel and old cast products. A Cupola and medium frequency furnaces are used at the foundry for melting recycled materials to be poured into green sand molds produced by match plate molding machines. Once the metal has been cast and shaken out, the products flow through the state of the art cleaning room (mill room) then on its way to the CNC machining centers.
  
  Section::::Engineering.
  