Exploitation of Alluvial Gold Deposits

Factors for choosing exploitation methods
In some areas auriferous mining is developed in a very incipient level, with elevated costs of operation due to factors such as scarcity of workers, supplies, equipment, tools and others that are very high in cost; added to the limited reserves that have less value, which obligate the mechanism and optimization of the actual methods including from the exploration, exploitation and recovery stage of the metal.

Excavation with front end loader or combined systems.
The mining system consists in open cut and open cast method. This method is mainly utilized in deposits that have a medium terrace, high ground that are not consolidated. For its operation a stationary plant is required and or a portable one, based integrally on gravimetric principles, whose recovery element is the sluices that have the riffling systems. The starter equipment, cargo and feeding to the washing plant will be done through front end loaders or other combined equipment, utilizing bulldozers for clearing of the overload of the area that is to be mined on. The evacuation of the thick tailings selected by the crosscurrent by means of a sieve can be done with the front end loaders, and the fine debris eliminated with venturi tubes and the provision of the water to the plant by a pumping system. In this method of mining there is the facility of exploring and sampling and there is a good amount of recovery since the deposit is dry; however there is the disadvantage that the unitary operation costs are high.

Draglines. These are used to dredge small deposits of a small amount of depth and for materials that are not consolidated, with enough amount of water and material without the bigger rocks. This is made up by a type of movable crane that has a beam of steel with a relatively large ratio of action, where the scoop is subject to two steel cables, one of them operates through a pulley that is situated on the top extreme of the coach man’s seat and is used to lift, lower and pull back; the other cable is used to throw the scoop along the terrain, in order to fill and empty the scoop. The weight and the dimension of the scoop play an important role in the excavation; both the coach man’s seat as well as the scoop is activated from the booth of the crane by a series of winch moved by electric motors. The locomotion of the dragline can be mounted in caterpillar or crawler tractors with high capacity caterpillar track wheels.

The washing plant consists in a Washing plant that goes mounted on a hull or floating barge. The classifying element of the thick debris is the trommel, the recovery can be done through sluices with riffles or jigs and the elimination of the tailings is done with a transporting conveyor. The advantages of carrying the job out this way is the it digs the top part of the alluvial bank, vegetation, clay sand and other materials and places them in places where they do not interfere with the exploitation.