Spiral Classifiers

It consists of a slow rotating and gently elevating spiral screw in a tub with an inclined trough and its function is simple. Water is sprayed under pressure on to sand fines in the screen and the sand slurry is gently let into the classifier tub full of water without causing any turbulence. The silt and other impurities get floated and discharged over weirs. The coarser particles i.e. sand settle at the bottom. The double start screw rotating at slow speed rakes up the settled sand particles and conveys up through the inclined trough. This is a continuous process and as the washed sand moves up the excess water in the sand mix is drained back to the tub and at the discharge point a relatively water free sand is obtained.