Crude sand is classified and fractions stored in separate silos - with outlets metered to mix predetermined grain size distribution

摘要

The arrangement is intended for preparing a sand mixture with predetermined grain size distribution starting from unclassified crude sand (2). This sand is separated into a number of grain size fractions by classifier units (7-13; 7'-13'; 16,17,13"; 18,19,13"') and stored in separate silos (13-13"'). Each silo is provided with a metering unit (14-14'") at its outlet which permit selected quantities of each fraction to be withdrawn and moved (15-15"') to a mixing unit for preparing the required mixture. The classifier unit may receive the crude sand, pumped (4) in water, via a hydro-cyclone (5) which removes the transport water, grain size classification then by upward water flow (8,8') in classifier vessels (7,7') followed by screening on a vibrator screen (16) and dewatering screen (18) to produce the final coarse fractions.