Instrumentation and online control of hydrocyclones

Hydrocyclones are widely used in the mineral processing industry for classifying and thickening of slurries. Their controlled operation is important as variations in the particle sizes of outlet streams could affect down-stream processes resulting in poor overall performance and economic losses. A single parameter, defining the classifying efficiency of a hydrocyclone, is the d50 value. The d50 represents the separation of a particular particle size reporting 50% to the underflow and 50% to the overflow. The d50 is not a directly monitorable parameter, but has to be established from separation curves known as Tromp Curves. The authors examined the possibility of producing a consistent output product with minimum variations under various operational conditions by controlling the d50. A computer control system was realised and various control algorithms were developed to optimise performance of the cyclone. Some design parameters, such as vortex height and spigot opening, were made to function as operational parameters by acceptable alterations and appropriate instrumentation