Self-cleaning gravimetric and volumetric dosing apparatuses

A self-cleaning dosing apparatus comprising:

• a material hopper adapted to contain pellets of material;
• a feed screw;
• a first material outlet at the material hopper adapted to deliver pellets of material to a first end of the feed screw;
• a cylindrical insert surrounding the feed screw;
• a motor configured to rotate the feed screw inside of the cylindrical insert to push pellets of material to a second end of the feed screw where the pellets of material fall out of the cylindrical insert;
• a second material outlet located beneath the first end of the feed screw;
• a gate configured to selectively block the second material outlet;
• a piston configured to open the gate to unblock the second material outlet;
• a pump located under the second material outlet;
• and
• an air nozzle configured to create and direct a stream of air through the cylindrical insert;
• wherein:
• the motor is configured to reverse the direction of rotation of the feed screw to thereby transport pellets of material located between threads of the feed screw backwards towards the second material outlet;
• the air nozzle is configured to direct the stream of air to push pellets of material that have fallen to a bottom of the cylindrical insert back through the cylindrical insert towards the second material outlet;
• and
• the Venturi pump is configured to pull pellets of material from the material hopper through the first material outlet and from the feed screw through the second material outlet to direct the pellets of material out of the apparatus.