Dredge Section

 It is composed by the following equipment, machinery and accessories as mentioned in a specific developing country:

• Centrifuge pump or suction pump of 5” or 6”.
• Diesel motor, Yanmar, of 18 HP or 36 HP.
• Suction hoses of 5” (5” or 6”), 20 meters of length.
• Discharge hose of 5” or 6” – 10 meters of length.
• compressor of 200 PSI, Shulz.
• Diving equipment (suit, mask, mouth piece, belt).

Of these equipments, the ones which are submitted to higher waste are the pumps (inner waste), which must be repaired every thirty days.

The operation of dredging or lifting of the material of the bottom of the river is effectuated by the centrifuge pump; through the suction hose the pump is actioned by the diesel motor. The suctioned material by the pump is poured through the discharge hose in the mill hopper of reception of the wash sluices.

The suctioned material is constituted by a pulp of water and gravel, the owners of the rafts not taking no type of technical control referring to the relation water above gravel which passes through the pump, not knowing, hereby, the volume of the processed gravel by unit of time.

On the other hand, it was observed that the density of the pulp is variable during the process, this possibly depending by the experience and ability of the diver in the handling of the suction hose, as well as the changes of dredge sectors.

The depth of average dredging in the visited zone was of 12 m. having reached in some cases until 18 meters, according to what miners indicated.

Referentially, we will mention that according to information a suction pump of 6” lifts 150 m3 of pulp/hour, of which 4.5 or 7.5 m3 are solids, depending on the pellet of the material principally, and that in the same manner has a reach of suction of up to 30 m. of depth for the case of suction of slurry.

The control of dredging is under the charge of the divers which effectuate turns of 3h. For a work day of 9 hours, to provide the divers of air we can count on a compressor of 200 PSI, effectuating the control of air to the divers through a manometer placed in the covering of the boat.

The personnel who operates in this section is conformed by three divers for a one-day’s-work of 9 hours.