Heavy-Media Separation

Another method of concentrating ores and minerals by floating (but actually quite different from the flotation method described above) is known as the heavy- media separation or sink-float process. Here, the differences in specific gravity of the various minerals in the rock mined are used to achieve the desired separation of ore from gangue.

In the sink-float plant, coarsely crushed ore is fed into a suspension of finely ground ferrosilicon (or magnetite or another heavy mineral) in water. This suspension is carefully maintained at a specific gravity between that of the desired feed and the unwanted minerals or gangue. As a result, the heavier mineral components sink, and are retained, while the lighter constituents float, and are discarded.