What's the difference between a sand dredger and a sand extractor? Should the type of sand dredger be selected according to the water depth and sediment concentration? Thank you very much

Sand dredger is a general term, including grab sand dredger, chain bucket sand dredger, rake suction sand dredger and jet sand dredger. Sand dredgers are different in "pumping". They can use "pumping" and "sucking" sand mining, and only towed suction sand dredgers and jet sand dredgers are available. The model of the ship is mainly determined according to the thickness and depth of the sand layer and the amount of sand mining. Of course, we need to use a high-powered ship, because the project is large and the construction period is tight. Grab sand dredgers and chain bucket sand dredgers are mainly used in inland rivers, while trailing suction sand dredgers and jet sand dredgers are mainly used for dredging and filling offshore waterways. Example: Yang Jun 1 trailing suction dredger 20000m3 per hour; The cutter suction dredger of the Celestial Whale is 4500 cubic meters per hour. You should first choose the dredger type according to your own task.