Sorting diamonds or other minerals.

摘要

To sort diamonds from a large number of ore particles 2 conveyed along a wide feed path 1, a line is irradiated across the feed path 1 to excite Raman emission from the diamonds, emission from the ore particles 2 is collected using collection means 6 providing an aperture having an f number of one or less in the view looking across the feed path 1, a narrow band pass filter arrangement 9 filters out all emission from the ore particles except the Raman emission and such broad band luminescence as has frequencies in the narrow band, a signal is given responsive to the emission which passes through the filter arrangement 9, the effect of the broad band luminescence is subtracted 7, 8 from said signal 14, the presence of the diamond is sensed and its location identified 20, and the diamond is blown out of the other ore particles 2 by an ejector 23.