Table of Contents
Physical Separation in Science and Engineering
Volume 12, Issue 4, Pages 223-236

Electromagnetic De-Shaling of Coal

Faculty of Applied Earth Sciences, Delft University of Technology, Mijnbouwstraat 120, Delft 2628 RX, The Netherlands

Received 22 December 2003; Revised 20 January 2004

Copyright © 2003 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The efficiency with which an electromagnetic sensor array is able to distinguish density and ash content of coal and shale mixtures was determined experimentally. The investigated sensor was originally designed for automatic metal detection and sorting in industrial glass recycle processing, where it is widely applied. In coal preparation, the results indicate good possibilities to remove automatically the remaining shale from the coal product, or to recover the remaining coal from the waste rock. Compared to alternative methods, the system has advantages of simple construction, insensitivity to fluctuating dust or moisture levels and a proven industrial reference. Applications can be either sorting of lump-sized coal or coal separation in the 10–50mm size range in a dry preparation process.