Development of a model for predicting the screening performance of a vibrating screen

CIM Bulletin, Vol. 72, No. 804, 1979

V. K. KARRA, Senior Research Engineer, Process Machinery Division, Rexnord, Milwaukee, U.S.A.

A mathematical model for the performance of a vibrating screen is developed in terms of an oversize partition curve. This is a normalized curve for any assemblage of particles presented for screening when their size is normalized with respect to the 50 per cent passing size (d50 ) under the prevailing screening conditions. Based on the throughfall aperture (hT) of the wire mesh on the deck, the effects of oversize (% > hT), half-size under (%<0.5 hT), deck location and feed rate were evaluated using the existing screen sizing information. All these variables and also the near-mesh (1.25 hT x 0.75 hT) content (%) of the feed affect the d50.Performance data from different decks of a double-deck screen with various feed rates, size distributions and screen apertures were used to evaluate the near-mesh factor. Effects of wet screening and material bulk density are also incorporated in the model. This generalized model is useful for the simulation of a multiple-deck screen. It furnishes the sieve analysis information of all the deck output streams and therefore has a potential use in the over-all circuit evaluation when used in conjunction with relevant crushing and grinding performance models. An example illustrating the prediction capabilities of the model is given.
Keywords: Mineral engineering, Models, Screening, Vibrating screens, Partition curves, Sieve analysis, Metallurgy.