Method and apparatuses for pre-screening

A pre-screening assembly for a vibratory screening machine, comprising:

• a frame having a central spine;
• screen assemblies, including a first substantially vertical screen assembly, a second substantially vertical screen assembly and at least one substantially horizontal screen assembly, wherein the first and second substantially vertical screen assemblies are each disposed at an angle relative to the substantially horizontal screen assembly;
• and
• wherein the frame is configured to be attached to a central member of the vibratory screening machine and the screen assemblies are secured to the frame forming a pre-screening surface having a concave surface.

A method of screening a material, the method comprising:

• attaching a pre-screening assembly to a central member vibratory screen machine, the vibratory screen machine including a primary screening surface disposed between first and second walls of the screening machine, the primary screening area being divided into two screening areas by the central member and the pre-screen assembly including a pre-screening trough having a concave surface between first and second edges, wherein the pre-screening trough is suspended above the primary screening area and the first and second edges of the pre-screening assembly are spaced from the first and second walls of the screening machine, respectively;
• pre-screening the material on the pre-screening surface to generate a pre-screened material;
• and
• screening the pre-screened material on the primary screening surface.