Dry Beneficiation of Coal by Laser Sorting

The project was designed to demonstrate on a pilot scale, the technical viability of the laser based sorting process to coal cleaning. The project was managed by Callide coalfields with Barco Machine Vision Systems (Elbicon Pacific Pty Ltd), supplying and operating the processing unit. Financial support was obtained from Shell Coal and ACARP.

The project tested five different types of feed, in size ranges between 9.5mm and 75mm, at feed rates up to 32 tph. An open day of demonstrating the process was attended by industry representatives from a wide range of interests. The main conclusions were:-

1. The project demonstrated that laser sorting as designed by Barco Machine Vision Systems, is a technically viable process for the separation of coal and impurities.

2. The process offers a tool towards the development of deposits in remote and/or arid areas.

3. The process offers substantial advantages:

• little to no water required, eliminates the expensive auxiliary circuits
• Simplicity, only screening and conveying are involved
• Dry processing maintains/improves energy content of product.
• Minimal manning requirements
• Operating cost can be expected to be lower than for wet processing of the same size ranges.
• Reduced environmental impact.

4. The process needs to be 'tuned' for each coal, however, changes from on type of coal to another can be almost instantaneous, once the program for each type has been developed.

5. The optimum size for best performance indicated by the tests was >25mm. On sizes below 25mm better performance than shown by the tests is expected to be achievable with more refined tuning of system parameters. This was not possible in the limited time available for the trials.

6. Performance on very high ash, high reject content feeds was especially good, indicating a role for cleaning up high ash coarse material which is often discarded in most mines.

A number of observations relevant to the development and application of the process were also recorded, together with suggestions for future work.

The report was submitted in two volumes. Volume 1 is the main report and contains details of the equipment, the test procedure, summary of results and conclusions. Volume 2 contains the project proposal, and all the laboratory results sheets for every sampling run taken in the project, and will be of limited interest.