Modern cable preparation plants typically consist of a combination of different granulators for material shredding and disintegration, separation plants for the copper fraction, and air handling systems for material transport and dust removal. First, the long cables are pre-shredded into short pieces and then crushed by granulators until the copper separates from the insulation. The degree of disintegration is determined, among other things, by the screen size in the granulator. In the case of thin wires or stranded cables in particular, very fine comminution is required to break the mechanical bond between the copper wire or strand and the plastic insulation.
The separation between copper and plastic insulation is then carried out with so-called setting tables. When operating cable preparation plants, the focus is always on producing a copper fraction that is as one hundred percent clean as possible. This is particularly important because even small impurities in the copper (for example, from plastic particles) lead to considerable reductions in revenue when the copper is sold to the smelter.
For technical reasons, setting tables do not succeed to the desired extent in producing a highly concentrated, plastic-free copper fraction on the one hand and a copper-free plastic insulation on the other.
Depending on the type of recycled cable, considerable amounts of copper are sometimes lost in the plastic waste in the form of fine copper strands and other small metal particles. Typical copper losses can be between 2 % and 12 %, depending on the cable type.
The recovery of this residual copper fraction is therefore a must in order to ensure the economic efficiency of the entire cable preparation process. This fine residual copper can be easily recovered by dry means with electrostatic separators.
The result is higher copper yields, thus increased economic efficiency of the entire recycling process and minimized copper losses due to metal-free plastic granules.