This is the most efficient single piece of equipment for separating minerals and waste with different specific gravities. The graphic above demomstrates the various processes combined in the Drum Plant.
It can separate raw material which is 50% coal and 50% shale.
Operation – 2 product separator
The dense medium drum is horizontal and revolves slowly (about 1 – 3 rpm). As the raw material enters the drum, magnetite is added via the water circuit to achieve the required density. Separation is achieved entirely by the buoyancy of the medium; dynamic effect plays no part. The coal floats near the surface of the medium and flows out of the end of the drum. The heavier shale falls to the bottom of the drum and is moved along the scrolls to perforated lifters which scoop it into a waste chute.
Operation – 3 product separator
This drum has a second chamber which repeats the process (at a higher separation gravity) thus producing prime coal, middlings and shale.