Particle shape of copper milled by swing-hammer-type impact mill

In order to apply a shape sorting technique to recover the copper component from printed wiring board (PWB) scrap, the particle shape of copper milled by a swing-hammer-type impact mill was experimentally investigated. Copper plate and PWB scraps were used as samples. The effects of mill operating conditions, i.e,, hammer circumferential speed (v(c)) and screen aperture size (diam. d(s)), on shape and size distribution of milled products were examined. Sphericity and homogeneity in the shape of milled copper particles largely depended on mill operating conditions. In the cases of both copper plate and PWB scrap milling, the most effective operating conditions to obtain spherical copper particles were v(c) similar or equal to 50 m s(-1) and d(s)=1 mm, and to obtain homogeneous shaped copper particles v(c)=70 m s(-1) and d(s)=1 mm. The most effective operating conditions of the mill to recover the copper component from PWB scrap using an inclined vibrating plate (IVP) were v(c) similar or equal to 70 m s(-1) and d(s)=1 mm.