Liberation of composite waste from manufactured products

With regard to liberation, composite materials resulting from industrial manufacturing processes differ from locked mineral resources. The simultaneous requirements of low weight, high strength and apparent softness etc., ask for the combination of materials with different mechanical properties. These composites can be liberated by selective comminution, where a defined stress by impact or pressure causes breakage of only one component of the composite, Similarly by shear it is possible to detach different components at their interface due to focusing of strains at the transition of materials. In our experiments good results were obtained for various samples of manufacturing waste and used products. In addition, the interface between different materials of manufactured composites is rather small, i.e, the bond is considerably lower than for natural mineral resources where the interface dimension is sometimes a fractal, This is due to geometrical simplicity of manufactured goods like cables and other layer composites. For the case of known interface area A and volume V of a single part of composite, a useful length x = V/A can be derived. This geometrical interface factor x enables us to predict the particle size D necessary to achieve a certain liberation rate L = 1 - D/x, These explanations indicate that the particularities of manufactured composites lead to new possibilities of liberation by comminution.