A method and device for separating light fractions, in particular longitudinally extending wood (27), from granulometrically sieved rubble mixtures (9), in which on a vibrating panel (3), are arranged a plurality of partition walls (7) defining channels (8) for orienting and longitudinally guiding the rods (27), where is provided a variable size composite opening (13) allowing to from a first curtain (21) comprising the heavy fractions and smaller light fractions, and a second curtain (24) formed by light paper and larger synthetic sheet material fractions and wood 'rods' (27) or only by the latter. The subject separating device (1) can be used as an end separating stage, and can practically provide a recovery of the actual end weight due to the residual presence of the light fraction comprising the wood rods (27) to prevent any disposal of in disposal sites, since the rods (27) are cleaned and accordingly can be reused. Moreover, the end inert material, after the above mentioned operation, is cleaner and has an improved value.