At the recent Kimberley Diamond Symposium and Trade show, Russian equipment manufacturer, Bourevestnik, demonstrated their latest diamond x-ray fluorescence separator technology.
The diamond symposium took place in the old mining town of Kimberley, South Africa from 11 to 13 September 2014, and followed in the footsteps of the highly successful ‘Diamonds in Kimberley Symposium’ held in Kimberley in August 2007.
More refined separator
Bourevestnik, an affiliate branch of leading diamond producer Alrosa, says its latest separator technology is a more refined x-ray fluorescence separator for second-stage processing.
An x-ray fluorescence separator works on the basis of diamond emitting light (fluoresces) when exposed to x-rays. A thin stream of particles from the concentrate falls through the air under an intense beam of x-rays.
The recovery of diamonds from kimberlite or alluvial gravel, whether on land or sea, requires a processing plant, explains Bourevestnik.
These plants consist of a milling or crushing component, a scrubbing and screening component that is followed by dense media separation (DMS) and thereafter x-ray or grease sorting for final diamond recovery.
When a diamond fluoresces, it activates a photodetector that triggers a jet of air which deflects the diamond in to a collector box.
This system is also completely enclosed or hands-off and provides significantly increased security in during the final recovery process.
Analysing diamond type
Care must be taken to accurately analyse the type of diamonds produced from each deposit as this will have an effect on the final recovery and determine which technology is most suitable.
Certain diamonds may be coated with material that is ‘wettable’, requiring treatment before the recovery process.
Other diamonds, particularly the more valuable type II stones, do not respond well to x-rays, which requires the use of other technologies such as ‘grease technology’.
Bourevestnik says its second more refined x-ray fluorescence separator is designed for the second-stage processing.
The x-ray fluorescence separator plants can be fitted quite snugly, with room to spare, in an adapted trailer-mounted shipping container, reports the company.
Today, there are more than 1 400 of these sorters operating around the world.