The Motion of Mineral Sand Particles on the Roll in High Tension Separators

Abstract

A number of models of the high tension roll separator have been described in the literature. All the models, in their calculation of the centrifugal force component of the force balance, appear to assume that particles introduced onto the top of the roll instantaneously reach roll speed. This paper questions that assumption. A theoretical analysis of the forces involved suggests that particles almost certainly do not reach roll speed (even if they have been charged in a corona field) until they have been carried a considerable distance with the roll. Experimental evidence was found to confirm the theoretical analysis, with 150 – 180 μm zircon particles having a speed of 180 rpm after travelling 55 degrees on a roll revolving at 275 rpm.