Drum-type sand classifier

A wet-type sand classifier comprising:

• a. a rotary drum which has a front outlet at its front end and a rear outlet at its rear end,
• b. a feeding means for feeding muddy water containing sand into said drum, said feeding means being enclosed by said drum and disposed concentrically within said drum, and attached to said drum for rotation with said drum,
• c. a classifying means for causing sand which is contained in said muddy water to settle onto the bottom of said drum and transferring said settled sand towards the rear end of said drum, said classifying means being disposed on the interior surface of said drum and covering the entire length of said drum, said classifying means comprising a plurality of helicoid blades of the same pitch which are fixedly secured to the inner wall of said drum at regular intervals, said helicoid blades being of a height which gradually increases toward the rear end of said drum, and a plurality of paddles radially disposed around the inner periphery of said drum at the rear end of said drum, each of said paddles having a number of apertures on the entire surface thereof for separating the water from the sand before the sand is discharged from the classifier, and
• d. a discharging means for expelling said transferred sand from the rear outlet of said drum, said discharging means being disposed at the rear end of said drum and attached to said drum for rotation with said drum, whereby substantially water-free classified sand of a desired size range is produced by the rotation of said drum with minimum wear of the classifier due to friction from the sand.