Application of pulsed HV discharges to material fragmentation and recycling

The physical basis of electric impulse fragmentation and its applications to the recycling of composite materials are reviewed. The method is based on the initiation of a pulsed electric discharge inside the solid dielectric material. With pulse amplitudes of /spl sim/300 kV, material layers of /spl sim/2 cm can be punctured. Specific energy deposition, of /spl lsim/100 J/cm at a GW power level, leads to pressure buildup of /spl lsim/10/sup 10/ Pa in the discharge channel. Pressure waves and radially propagating cracks are launched into the solid body, which can lead to the separation of inclusions from the matrix or to detachment at material boundaries. To induce the discharge in the solid dielectric it must be immersed in a dielectric liquid with higher breakdown strength. Most applications use water, which has excellent breakdown strength at fast ramp rates and, due to its high permittivity, leads to field concentration in the solid dielectric. Electric impulse fragmentation is a clean physical method without any environmental burden and therefore well suited for recycling applications. In this paper we consider applications in the fields of demolition debris, incineration ashes, contaminated surface layers, electric appliances, glass, and elastoplastic materials. Finally, the economy and the scaling of the technique to large material throughput are discussed.