The following Three movies are all of the same Gravel Classifier at a different mine. This unit is different from the previous one. It is basically a modified Gravel and sand classifier that you would find at a gravel pit. A sluice box has been added to the final stage. This setup uses a motor to shake the "Hopper" to help the big rocks move down the incline while the pressurized water sprays over them to wash smaller gravel and gold off of them. The boulders are then carried by a conveyor belt out of the way while the smaller gravel, sand and GOLD are diverted into the sluice box.
Underwater Closeup (2 MB Quicktime Movie) of the suction dredge nozzle sucking up gravel.