Patent ID: 8636149

Claim:
A sand washing apparatus for separating organic material from a mixture comprising sand and organic material, the apparatus comprising: (a) a wash chamber for accepting a mixture comprising sand and organic material, the chamber including a lower portion in a shape of a cylinder with an internal wall through which sand can descend in a downward direction and water can flow in an upward direction; and (b) an agitator comprising a screw having two or more flights extending into the lower portion such that the two or more flights extend across an internal periphery of the cylinder, the screw having a root diameter and an outer diameter, wherein the agitator and lower portion of the wash chamber are arranged relative to each other such that rotation of the agitator creates a lifting action tending to force at least a first portion of sand descending through or already present in the cylinder to flow in the upward direction and permits a second portion of sand to sink in the downward direction because of gaps located between the root diameter and the outer diameter of the screw in the cylinder.