Phase Two Development of a Low Cost Online Measurement of Particle Size and Density for Diagnostics Across the Fine Coal Circuit (Particle Profiler)

This project is based around the development of a prototype system (Particle Profiler) for online analysis of coal quality in the fine circuit of a coal preparation plant (ie in the range of -2+0.125mm). The system determines the distribution of particle size and density using an optical imaging technique. By tracking individual particles as they settle through the optical cell, the size and velocity are used to calculate particle density. The project builds upon fundamental testing in previous work undertaken in project C26014 which found that particles could be estimated within 1-2% in size and 3.4% of relative density using this tracking method.

In this project, the software was developed to enable:

• automatic sampling,
• image acquisition,
• tracking and data extraction,
• statistical histograms of size, velocity and density and
• summary reporting suitable for integration with the plant SCADA systems.

Hardware developments included the use of a new optical cell design and a valve/pump assembly for sampling. Overall, the system takes approximately 8 minutes to conduct a full sample cycle, with the image analysis found to be dependent on computing power (between 1-3 minutes) and tracking time dependent on lowest particle size.

The testing of the system occurred in three phases which are detailed in the report.

The next stages of development should involve pre-commercial trials of a ruggedised prototype system at a coal preparation plant. By necessity, much of the learnings, development cycle and design parameters have not been included in this report due to commercial sensitivity. It is believed that there are opportunities to extend the optical cells to coarse and ultrafine particle sizes, but that specific sampling systems are in need of better design. The data generated in approximately 8 minutes could be potentially incorporated into an automated PID control loop for separation devices and may also be used for prediction of maintenance issues. Of particular novelty in this system, is the measurement of particle settling velocity, which forms the basis of many separation processes in coal preparation. While its use here has been for the determination of particle density (and hence quality), the availability of measured particle settling rate data could have intrinsic value as a coal characterisation variable. It was found that the ability to further disect the density dataset into finer particle size ranges offered greater insight into our coal samples quality. Its use as a dataset could lead to improved decisions in optimising plant design and also in designing of separation units, such through size-specific partition curves.