Recycling of Copper and Copper Alloys

Recycling saves resources, reduces the footprint on the environment, and conserves energy.  Idealy suited for reuse, copper is perhaps the most recycled material the world over.  Thus, the marketplace has been well organised for the trading of scrap copper and copper alloys for generations.

A deciding factor in the production of metal out of scrap, as well as the energy savings, is the final quality of the recycled materials.  Were the recycled metal's quality not sufficient, one would question the energy costs required to recycle the material.  This is where the recycling of copper differs from that of other metals and plastics. Recycled copper's quality matches that of new copper and, indeed, cannot be distinguished from primary material regardless of how many times it has been reprocessed.  That's the copper advantage. 

The classic rate of recycling is calculated by the amount of secondary material that is produced per year in relation to the total yearly production.  Using this definition, copper has a recycling rate of approximately 45%.  This figure, however, does not provide much information about the true reuse of the resource.  The recycling rate does not account for the fact that much of the salvaged material comes from old machinery that was created when the copper production rate was much lower.  The classic recycling rate, however, is calculated on the much higher current production.  This means that the recycling rate is misleading because it does not provide a true measure of how much old material is being reused.

A more accurate copper recycling rate would be reached if the useful life expecatancies of copper products were used as a basis for calculation. Copper and copper alloys, thanks to their durability, have a long useful life expectancy, as table 1 shows below: 

Use inUseful Life Expectancy
small electric motors10 - 12 years

automobiles

15 - 18 years (life of the automobile)
cables30 - 40 years
buildings60 - 80 years

Table 1: Useful life expectancy of various copper products

Were the average use expectency of 35 years used as a base, you would arrive at a "true" recycling rate of almost 80%.  With the "true" recycling rate, it is clear how valuable reused copper is.  For example, it is estimated that 90% of a scrapped automobile's copper is extracted.  Additionally, with the modernization of extraction techniques, it is possible to recycle more and more copper from used electronics. 

Nevertheless, the recycling rate implies that 45% of the total demand for copper can be met through the use of recycled materials.  Because Germany has all but no copper mining of its own, the reuse of older materials will be an important resource in satisfying the demand for the metal. 

Copper recycling can be differentiated between direct scrap use in semifinished products and the use of return material, that can be later used for copper refinement.  Reminants of semi-finished products, such as shavings, chads and compact scrap, are often gathered up again and directly resmelted and reused.  Rods from voltage metering (free cutting alloys), are, for example, nearly made from 100% recycled materials.  Resmelted casings from the casting production of ingot metals are also almost exclusively from recycled materials.

Return materials that will be made into secondary copper can be grouped into the following three categories:

  • New scrap such as production extras and semi-finished products that are without impurities such as shavings or chads.
  • Old scrap pulled from used goods: remnants of cables, electronic, automobile, armature scrap with a relatively high and calculable copper content.
  • Semini-finished products or residual material such as slag, dross, and galvanic sludge, etc. 

Scrap can be further categorised:

  • Scrap that is mixed with other metals or non-metal materials.  Belonging in this category are electric motors, automobile scrap, electronic scrap, etc.  The automobile industry undertakes much of the scrap recycling in this category. 
  • Sorted, pure scrap such as wire or cable that can be directly resmelted.
  • Alloy scrap with a certain composition of brass, bronze, red bronze, etc. These materials can be processed by resmelting or fire-refinement.
  • Scrap that is mixed with other metals or non-metal materials. Belonging in this category are electric motors, automobile scrap, electronic scrap, etc. The automobile industry undertakes much of the scrap recycling in this category.

The first step in scrap recycling is the mechanical shredding and sorting of the materials.  Essential equipment for this process includes shredders, magnetic and air separators, and sink-float seperation systems.  For some scrap, namely auto parts (starters, alternators, cable harnesses, radiators, catalytic converters), the materials are best picked apart and separated by hand.   

Auto scrap materials are then further reduced by a shredder into 100 to 250 mm pieces.  An air separator sorts the mixture into heavy and light materials.  A magnetic separator then pulls the metals out of the heavy materials.  To further separate the various types of metals, a combination of processes are used such as eddy current separation, electronic separation, laser impulse, etc.  Materials identified as containing copper are gathered for recycling.  Other high-quality scrap such as wire and cord must be prepared for recycling beforehand.  For example, a cryogenic process is used to remove the plastic coatings.  Electric scrap, that is so often a combination of metals and plastics, is best processed by a firm that specialises in recycling these materials.