In the InfoMine Library there is an interesting technical paper that explains how ore can be separated from waste material by using image processing techniques.
The paper is written by Aiyush Suhasaria, an undergraduate student in the Department of Mining Engineering at IIT Kharagpur, India, and Khanindra Pathak, a professor in the same department.
In their paper, they describe the technique as follows:
To separate the ore from the waste and gangue materials Image Processing techniques are applied using live video of the ore and gangue mixture on the conveyor. The optical data captured by camera (sensor) is transferred via an optical data transferring system to a processor. The image processing techniques are applied to differentiate the ore and gangue material. The output signal is used to actuate appropriate mechanisms to direct the feed towards appropriate outgoing line. Thus the system reduces the ore dilution and help in enhancing the ore grade.
The paper presents a laboratory scale test of the technique and reports on the software’s output.
Take a look at the paper at this link: http://www.infomine.com/publications/docs/Suhasaria2012.pdf