Coal Preparation » Gravity Separation
This project evaluated the performance of a large diameter (1450mm cyclone diameter) high capacity (362mm equivalent inlet diameter) dense medium cyclone, treating a full size range of -50+1.4wwmm at cut-points in the range 1.60-1.70RD and 10-15% NG (+/-0.1RD). Under the broad range of feed solids loading / M:C ratios (3:1 to 6:1), and feed pressure conditions (7D to 10D), that were tested, the measured performance of both coarse and fine particles were similar to those that were achieved with smaller diameter cyclones. Low density tails on the partition curves were shown to be insignificant and there was no discernible "breakaway" particle size where separation efficiency rapidly deteriorated.
Partitioning of particles to as small as 0.250mm was determined to be occurring to the extent that +0.250mm material in the DMC overflow medium was generally suitable material for inclusion in the plant product stream.
Existing industry models for Ep by particle size and volumetric split in a DMC were found to be inadequate in describing the performance of large diameter high capacity dense medium cyclones. Models that showed reasonable correlation for estimation of DMC feed volume against volumes determined by pump curve calculation methods were identified.
Effective sample program design, analysis management mechanisms and data validation techniques are described that were able to produce accurate and reliable data sets for large scale dense medium cyclone installations. The magnitude of the sampling and analytical errors involved in generating partition curves and subsequent efficiency parameter interpolation for this project were shown to be minimal in the outcomes of a duplicate test run.