A device for the mechanical separation of wet natural manure masses into a wet phase and a dry phase, said device comprising:
- a substantially horizontal cylindrical sleeve having an upstream end longitudinally spaced from a downstream end, means for receiving masses of natural manure at said upstream end of said sleeve, said sleeve having a cylindrical strainer portion intermediate said ends of said sleeve through which the wet phase of the manure masses is discharged;
- a jacket surrounding said strainer portion of said sleeve for receiving the wet phase of the manure masses, said jacket having at least one outlet for the wet phase of the manure masses;
- a rotatable screw conveyor arranged concentrically within said sleeve, said screw conveyor comprising a central, driven rotary shaft carrying a first longitudinally extending screw thread section having an upstream end and a downstream end, said upstream end of said first screw thread section being proximate to said upstream end of said sleeve, said first screw thread section extending along a portion of said strainer portion of said sleeve so that said downstream end of said screw thread section is positioned in said sleeve at a location that is longitudinally spaced in the upstream direction from said downstream end of said sleeve, said first screw thread section moving manure masses longitudinally through said sleeve from said upstream end of said sleeve toward said downstream end of said sleeve, said rotary shaft carrying a second longitudinally extending screw thread section positioned within said strainer portion and having an upstream end and a downstream end, said downstream end of said first screw thread section being longitudinally separated from said upstream end of said second screw thread section along said rotary shaft to form a longitudinal space along said shaft intermediate said downstream end of said first screw thread section and said upstream end of said second screw thread section, said longitudinal space forming a corresponding longitudinal, annular zone within said sleeve which is free of obstruction around the entire circumference of said shaft, said longitudinal, annular zone being located upstream of said downstream end of said sleeve and establishing a zone within said sleeve in which a plug of relatively dry manure is continuously formed from the manure masses moved by said first screw thread section, said plug comprising a barrier in said sleeve exerting pressure on said manure masses moved through said sleeve by said first screw thread section for assisting in removing the wet phase from the manure masses upstream of said plug for discharge into said jacket, said second screw thread section removing manure in its dry phase from a downstream end of said manure plug for discharge from said downstream end of said sleeve;
- and
- driving means for rotating said screw conveyor.