Process equipment supplier McLanahan recently noted that for more than half a century, Hydrosizers have offered the mining industry the means to achieve highly efficient classification by size as well as the capability to separate particles by specific gravity using a dense bed of teetered solids. McLanahan’s Hydrosizers are based on the designs of the former LPT Group, which McLanahan acquired more than 20 years ago.

Hydrosizers accept feed material into the top of the unit via a central feed well. Water is injected near the center of the unit to create an upward-rising current which establishes a zone of suspended solids. Smaller or less dense particles are lifted out of the Hydrosizer and over the weir, while larger or denser particles pass through the current to be collected in the underflow cone for discharge.

Over the years, McLanahan has updated Hydrosizer design; for example, switching from square-shaped units to round to eliminate potential dead zones of material buildup in the corners. It also added side-accessible teeter water pipes for easier, faster and safer maintenance of the water distribution system and can tailor standard designs to meet customers’ specific needs.

A lithium mine in Western Australia purchased one of its Hydrosizer units to remove mica from its spodumene-bearing pegmatite ore. For that project, McLanahan included ceramic ball valves in the Hydrosizer instead of the standard pinch and linear dart valves. These ceramic valves are ported for linear control and are expected to perform better than rubber-lined units for this duty. The valves also have special v-gates to prevent them from closing on a pebble of spodumene ore and destroying the ceramic valve.

In another application, a customer making iron ore pellets needed its iron ore concentrate to contain less than 1% silica. Hydrosizers were used to upgrade the conventional 5%-silica concentrate to less than 1%. The overflow from one Hydrosizer was then treated in other Hydrosizers to bring the concentrate back down to less than 5% silica for normal pellet grade.

Hydrosizers are also used in preparation of phosphate for flotation circuits which typically can’t float-out particles coarser than 0.5 mm; consequently, a number of phosphate operations use Hydrosizers to achieve the 0.5-mm separation. The Hydrosizer underflow can be sent back to the grinding circuit or to tailings, depending on grade, while the fines that overflow the unit are sent to the flotation circuit. Other applications, according to McLanahan, include the processing of tantalum, feldspar, garnet, silica, mineral sands, coal and more.