Screening And Classification
The size of screen aperture needed so that the oversize particles can be separated completely into sand and coal by elutriation = 4.6056 x 10-5 m The required water velocity = 1.9079 x 10 -3 m/sec By operating at the water velocity of 1.9079 x 10 -3 m/sec, coal particles will be carried along with water, and sand particles will settle down.