 As the buckets pass over the top tumbler they discharge into a hopper from where a chute directs the dredged material into a revolving (or trommel) screen.Here it is washed by high pressure water jets, the fine ore-bearing material passing through the perforations (normally about in size) and proceeding to the treatment plant and the oversize material continuing over the screen.The undersize from the screen is passed to ore concentrating and recovery equipment, consisting at Nettle Creek of a series of pulsating jigs.