Apparatus for controlling discharge of classified sand from a hydraulic classifier

An hydraulic classifier including means for discharging a particulate product comprising:

• a. a vessel tapering in a downward direction and having means for discharging fines at the top and a bottom formed with an aperture;
• b. a rotor in said vessel including
• 1. a shaft having an upright axis,
• 2. drive means for rotating said shaft about said axis,
• 3. an upwardly tapering, hollow member mounted on said shaft and upwardly spaced from said aperture, said member having an annular lower orifice and an annular upper orifice smaller than said lower orifice,
• 4. a flow tube mounted on said shaft for receiving liquid upwardly discharged from said upper orifice for upward flow,
• 5. agitating means projecting radially outward beyond said flow tube above said hollow member, and
• 6. means on said shaft below said hollow member for forcing cleaned particular product through said aperture;
• c. washing means on said vessel for directing a liquid washing medium radially inward against said hollow member intermediate said orifices thereof, whereby said washing medium is deflected into said flow tube and draws additional liquid from said upper orifice,
• 1. said flow tube, said hollow member, and the lowermost portion of said shaft bounding an annular path for downward movement of a suspension of particulate material in liquid in a radially inward direction, said path being bounded by said vessel in a radially outward direction,
• 2. said agitating means projecting into said path;
• and
• d. feeding means for feeding particulate material to a portion of said vessel above said flow tube.