There are two different types of scrap metal: ferrous and non-ferrous. Non-ferrous metals (such as copper, aluminium, gold, silver and zinc) can be recycled again and again as they won’t lose their chemical properties during the recycling process, making them extremely valuable. Ferrous metals are more common and include anything made of either steel or iron.
Once the scrap metal reaches the yard – the process of actually recycyling is where it gets intersting:
Firstly, metals are separated from non-metal materials from the load and then the ferrous metals and non-ferrous metals are separated with the use of machinery, magnets and electrical currents. Then the metals are sorted by type by looking at their colour and weight. Lastly, the metals are sorted by cleanliness and ensuring they do not cross-contaminate each other any further.
This part of the process involves compacting the metal together and then cutting them into smaller pieces using hydraulic machinery. Then, it is shredded into even smaller pieces so it’s ready for the next step in the process.
Now we have the smaller pieces, we are ready for the melting phase. This is done in a large furnace which is configured for each particular metal type as each type requires different levels of heat. Depending on the size of the metal and furnace, the process can take anywhere between minutes to hours. While this process does involve using energy, it is far less than needed to mine new metals.
As the metal is melted, impurities rise to the surface, and these can then be separated and removed – leaving only the pure metal. One method of purification is electrolysis where an electric current is passed through the metal and the pure metal is deposited at the cathode while the impure ones are dissolved. The impure metal is an anode and the pure metal is a cathode. The soluble salt from the metal is an electrolyte. These impurities collect below the anode.
The final step in the scrap metal recycling process is where the raw molten material is turned into the finished product. The melted metals are put through a conveyor belt that takes them into a cooling chamber which solidifies them. Some metals are melted into sheets while others compacted into shapes or blocks using moulds.