Recycling of composite materials is assuming a growing relevance in Europe, either in economic (materials and energy recovery) or in environmental (impact reduction in good manufacturing) terms. Particularly, the recovery of metallic compounds (when they do not degrade and their chemical characteristics remain unaltered over time) can be recycled more easily than non-metallic compounds. Some of these waste materials have to be dismantled and treated before their definitive disposal. This experimental work, in particular, has been focused on the processes linked to recycling of electric wire cables, constituted by copper filaments coated by special plastics. A preliminary characterization of components has been carried out to define the physical and chemical properties of composite materials, in order to design a proper treatment process. Comminution tests have been performed in order to obtain a proper liberation of the components taking into consideration different kinds of electric wire cables. In particular, the cryo-comminution allows improving liberation of constituents of composite materials, due to low temperature embrittlement. The temperature in the mill chamber has been conditioned by adopting different methods: i.e. under a CO2 flow and after conditioning in liquid nitrogen. Samples have been pre-conditioned by immersion in liquid nitrogen to improve the mill operating conditions. To evaluate the effects of embrittlement due to low temperature on comminution results, a set of experimental tests have been carried out at room temperature too. The samples have been comminuted in order to obtain a size reduction suitable to achieve a proper liberation degree. Finally, the products of the comminution process have been forwarded to a gravity separation process, which aim has been to recover the metallic fraction. The separation process efficiency has been evaluated, controlling the contamination, i.e. the plastic content in the metallic fraction. The experimental results have been compared and discussed, taking into consideration the different test conditions, in term of liberation and relative efficiency of the separation process.
Cryo-comminution of electric wire cables / Gaeta, A; LA MARCA, Floriana; Massacci, Paolo. - (2002). (Intervento presentato al convegno ESC 2002: 10TH EUROPEAN SYMPOSIUM ON COMMINUTION tenutosi a HEIDELBERG, GERMANY nel 2-5 SEPTEMBER, 2002).