Joint Evaluation of Monitoring Instruments for Dense Medium Cyclones

The objective of this project was to bring together at a single site the two research groups involved in dense medium cyclone (DMC) instrumentation and software development to demonstrate:

• A comprehensive DMC monitoring and measurement reporting capability; and
• The benefits in improved plant performance of having such a facility providing minute-by-minute process information that is otherwise not available.

The plant management at the New Acland coal preparation plant provided a unique environment for the conduct of this project. This project has allowed the extensive evaluation of a number of new monitoring/measurement devices which have the potential to significantly change the management and control of coal reparation plants in the future. The main activities were the investigation of:

• The devices over an extended period of time to develop an understanding of their ability to maintain their capability in the difficult process environment found in coal preparation plants. Action was taken when problems were encountered.
• The accuracy with which they could measure important plant processing conditions; for example the fluid density of a processing stream or the amount of solids on a screen.
• The potential for remote monitoring of their output to provide early warning that a measuring device was having problems, and the potential of these devices to be used in more autonomous operation.

The measurement devices employed and their location in the New Acland number 2 coal preparation plant are:

• Screen motion analysers located on the desliming and the product and reject drain and rinse screens. These give a clear understanding of the motion and condition of the screens and also provide an estimate of the tonnes of solids passing over the screens. The yield from the DMC circuit and an indication of the size distribution of the feed to the plant can then be quantified.
• Electrical Impedance Spectrometers (EIS) which provide measurements of the medium density and its composition. These were placed on the return correct medium, the overflow and underflow mediums and the feed medium.
• The Through Tile Density Meter and In Stream Density Meter were placed in the overflow pipe from the DMC vortex finder and underneath the product drain and rinse screen. These provided measurements of the amount of magnetite in the medium at these points in the circuit.

An e-newsletter has also been published for this project, highlighting its significance for the industry.