Abstract: A system for pre-processing material into groups of different sizes comprising three levels. The second level is positioned above the third level and below the first level. The first level comprising a feeding mechanism, one or more first screens coupled to ducts and having apertures, blowers and vacuum ducts, dust collectors and a diverter. The screens transport the material along the first level in a first direction while a portion is sifted away before being diverted to the second level. The second level comprising one or more second screens coupled to ducts and having apertures, blowers and vacuum ducts and a takeaway device. The screens transport the material along the second level in a second direction different than the first while a portion is sifted away before falling to the third level. The third level comprising blowers and vacuum ducts and takeaway devices for receiving a portion of the material.