Coal Preparation » Gravity Separation
This report represents a follow-on project from the first stage large diameter dense medium cyclone (LD DMC) project (ACARP C10048).
The use of LD DMCs has become widespread in the Australian coal industry and, in the future, they are likely to be the dominant processing unit. While the initial study gathered statistically significant data for the 1000 mm cyclone there were insufficient data supplied in relation to the larger cyclones, up to 1300 mm diameter. Prior study of the detailed trends for the 1000 mm diameter cyclone indicated that, for particle sizes below 4 mm, there were poorer efficiencies and higher cut points. Significantly more data were needed before any conclusions could be drawn on the performance of larger cyclones.
The thrust of this second stage project was to increase the performance knowledge of the larger dense medium cyclones. This was to provide a better understanding of the operational efficiency of the larger cyclones and allow the industry to optimise their plant designs and operations.
The project outcomes comprise efficiency data (size by size partition data and derived parameters) from new detailed sampling and analysis programs, and data on 1150 mm and 1300 mm cyclones from testing completed and published or contributed by others in the intervening period.
It has been determined that cut point spread (drift) is the principal contributor to overall cyclone Ep, rather than the Ep values achieved for individual size fractions, which were found to be relatively constant for any given size fraction.
The data generated from this project have been used to formulate suggested changes to modelling parameters for LD DMC.
The study has demonstrated that cyclone performance at many CPPs is sub-optimal, where design compromises can cause, and have led to, large financial losses due to reduced product coal recovery. The data obtained have been evaluated in terms of equipment configuration and operating practices.