A description of the application
There are three main groups of copper scrap to be recycled: Production scrap (copper content usually higher than 99.5%; also called clean scrap or new scrap, it is directly melted for products without further refining and therefore it is often out of the statistics); Old scrap (copper content typically higher than 90%; it usually enters the process chain of cathode production); Other materials (such as within electronic components, where the copper fraction is lower: ≈30%).
The challenges that appear regarding this application
In the end-of-life of copper containing products, different aspects have to be considered:
Identification and awareness: The first aspect is whether the collection is the most effective. For example, if a mobile phone ends in the stream of municipal waste, the metals will be lost. Creating awareness in the society is relevant, helping saving resources.
Weight and fractions: Regarding the preparation for recycling homogeneous material composition and high volumes of waste streams are the easiest to manage. But for example the miniaturization of products increases the complexity and variety of materials and disperses the material value with lower volumes per product. It becomes more challenging keeping the recycling as an economically viable option.
Selection of recycling option: The main challenge is ensuring that the right recycling route for the different metals is followed, which might not be always obvious. Different options might be considered, since for example the copper fraction frequently is not the main fraction in the products which contain this metal.
Considering the case of scrap from electronics products, for example, often steel case chassis or large aluminium heat sinks might determine the recycling option, if the copper is not clearly identifiable. If the electronics would enter steel or aluminium recycling routes without fractionising and separation before, the scrap quality would drop due to contamination from non-steel and non-aluminium components and all the other metals, besides steel and/or aluminium would be lost in the recycling process.
A similar example is given by the case of automotive industry, where steel has typically the main share in terms of weight in the scrap of a car and is easily identified. But the recycling of steel only recovers steel and (stainless) steel alloying elements. All the other (mainly non-ferrous) metals get lost in this process. Furthermore, if the copper, e.g. from cable harness and electronics remains in the scrap resulting from the shredding of a car, the whole value of steel would be lost due to contamination. For this reason, it is important to separate the copper fraction, ensuring that it doesn’t enter the steel smelting processes.
It is therefore of relevance to highlight the importance of having a separation, which considers recycling of copper and copper containing fractions, as besides getting the copper back, there are also further benefits associated.
How copper serves as a key factor to overcome this hurdle
Copper is, by its properties, a carrier for many metals, being a collector metal mainly for Platinum Group Metals (PGM), arsenic, selenium, and tellurium. At integrated copper smelters, additional treatment processes can be combined with the copper processes to recover also lead, nickel, zinc, silver and other elements. Besides, copper doesn’t lose its quality when recycled, even if it doesn’t dominate the material share of the recycling fraction.
Therefore copper has a high potential to carry many materials and high value metals such as PGM in the loop, which would most-likely be lost in aluminium or steel recycling routes. PGM can even define the scrap value, though it references only very low volumes in the waste streams. When processing copper, the metals, such as aluminium and steel do not have a negative influence in the metallurgical processes. Typically they are converted into oxides and move to the slag. In case of iron silicate, it is even applicable as by-product, substituting gravel. The collective elements remain with the copper up to the anodes. In the electrolysis, they are separated into the anode slime, whilst the copper ions move to the cathode. The results of the electrolysis is the copper cathode (99.999% pure copper) and the anode slime containing the collective elements, which can be then processed (mainly chemical processing).
From this perspective, copper supports a closed loop economy further then the two other main important recycling routes of steel and aluminium, by providing additional advantages through
- Enabling recovery of high value metals, which often drive the collection and separation also of small and dispersed waste streams due to their economic substance
- Allowing easier recycling by better identification of valuable recycling fractions and less difficulty at product separation into recycling fractions
- Less dependency on high scrap volumes
- Ensuring 100% property stability during endless material loops due to missing negative impacts from other elements
The key message as a conclusion
It is important to improve the existing collection systems, avoiding losses from the metals in general. The three metal recycling systems which dominate the market are steel, aluminium and copper. Whilst steel and aluminium require fairly prepared, suitable fractions from End of Life (EoL) products in order to avoid contamination with negative effects on properties from some elements, copper serves as collection metal. It carries high value metals, such as PGM and Critical Raw materials (CMR), during its processing and enables their recycling too. It almost doesn’t suffer negative contamination from other elements and it keeps its properties without losses of quality during endless life cycle loops.
Copper is the reference metal for circular economy.
The Value Chain of Copper – from Mining to Application. European Copper Institute, 2014
E-Book: International Resource Panel Work on Global Metal Flows. UNEP, 2013