Patent ID: 7905358
Filing Date: 2011-03-15
Classification: B07B

Abstract:
1. A method of screening solid particulate ammonium perchlorate, the method comprising passing particles of solid ammonium perchlorate through a composite screen comprising: passing the plurality of particles of solid ammonium perchlorate through a first plurality of apertures in a generally planar first screen; passing a first fraction of the plurality of particles of solid ammonium perchlorate through a second plurality of apertures in at least one perforated region of a plurality of perforated regions of a second non-planar screen, the at least one perforated region of the second screen being disposed adjacent the first screen and oriented at an angle relative to the first screen; and retaining an additional fraction of the plurality of particles of solid ammonium perchlorate on at least one elongated, non-perforated valley region of the non-planar second screen between two perforated regions of the plurality of perforated regions to prevent the additional fraction of the plurality of particles of solid ammonium perchlorate from passing through the at least one perforated region of the plurality of perforated regions of the non-planar second screen.