Medium Quality and DMC Performance: Effect of Clay and Fine Coal

Abstract

A closed-loop medium circuit incorporating a 150 mm Dense Medium Cyclone (DMC) has been developed at the CSIRO QCAT laboratory to investigate the effect of changing the medium quality on medium stability. The dimensions of the cyclone were similar to the Dutch State Mines recommended values, except for the spigot. This was set at 35 mm since this provided the best operation and 2 mm colored tracers were available for determination of the partitioning performance of the DMC. For mediums with clay, magnetite, and/or fine coal, there is a considerable spread in the values obtained for overflow and underflow densities and the separation density of the tracers at each feed density. This is clear evidence that the composition of the medium (the medium quality) does influence the density differential and the effect becomes very significant for feed densities below 1.4. Empirically derived quantitative relationships were obtained for the underflow (RhoU) and overflow (RhoO) medium densities and separation density (RD50) using multilinear regression analysis. This improved quantitative understanding will allow the application of “smart sensors” to improve the level of process control that could be applied to a DMC circuit.