Processing Options: GravityGravity
A gravity circuit uses the high density of gold relative to the rock it occurs in. A gravity circuit only works when gold exists as discrete grains, large enough to be differentiated from the other rock. Many ore types contain gold so fine that gravity is not effective. In practice a gravity circuit will be part of a larger processing circuit that includes methods to recover the fine gold after the coarse gold has been removed. In its simplest form, gravity is used when gold panning. Sediment and water is agitated allowing the heavier gold grains to fall to the base of the pan. The lighter sediments can then be removed leaving a concentrate containing much of the gold. The same principles apply to the large scale process at a mine but involves a centrifuge to maximise the separation. Crushed ore and water are fed into the centrifuge. The heavier sediment including gold pass through the base and the loghter waste products through the top. In both cases the waste material will still have gold in it, and so will be processed by flotation or CIL/CIP further down the line. |