Suction Dredges

This is a type of centrifugal pump that is placed in a metallic or a wooden pontoon. It sucks by the means of a semi rigid hose or steel tubing, mixture of water and auriferous material that can be found in the river beds, lakes, swamps etc, emptying out the suctioned material into a conventional sluice made out of wood or steel in one or two stretches in back currents. For the process of the suction in diameters of hoses of 6 inches is required the usage of scuba outfits; for suction hoses or tubes of 8 inches or more, the performance of the suction element is by the means of a hoist chain and winch that is run on a diesel motor, the head or tube terminal submerged consists in a milling cutter, the mixed material of gravel and water, which is of thirty percent and seventy percent, is absorbed by a gravely pump or from solids of moulded or forged steel construction, wrapped with sheets of steel, the roll and impact face with extra strong welding, sealing system, the material that is suctioned goes into a primary screen that takes care of eliminating the bigger gravel of half an inch, and the material that is smaller goes into a system of sluices, positioned with three layers of jute with riffles of 1 inch. 

Surface Suction Dredges
Surface dredges are devices that float or sit on the surface of the water. Suction on the other hand, refers to the fact that it utilizes a type of vacuum in order to build up or lift material to the surface, whether it is water, mud, gravel, coins, silver, gold, rocks etc. in a nutshell, anything that is small enough to fit through a suction hose. After it has been sucked up, the material is then released through or into a classifying device more frequently known as a sluice box. The size of a dredge is determined by the diameter of the hose and its intake. Recreational and weekend prospectors often times prefer using the 1 ½ to 2 inch ones. The grand thing about the dredges these days is that they are not heavy to carry around and are portable and they are built out of very simple to use components all of which need to work well in order for a successful operation to be carried out.