Kimberlite samples are processed through Stornoway's 5 tonne per hour dense media separation ("DMS") plant in North Vancouver, our 10 tonne per hour DMS on site at the Renard Project, or in our 1.5 tonne per hour facility in Thunderbay (operated by Microlithics Laboratories) to recover diamonds greater than 0.85 mm as measured by a square aperture screen (cut-off sieve size may vary with sample size) .
Samples are first disaggregated through a reiterative crushing process designed to limit the risk of diamond breakage. The crushed kimberlite is then processed through a sequence of washers and screens, and fed into the core of the DMS plant. In essence, this device consists of a high-pressure centrifuge or "cyclone". In the operation of the DMS plant, the kimberlitic material is mixed with water and ferrosilicon, a dense, fine-grained powder which effectively increases the density of the process water. The resulting slurry is spun at high speeds, creating a very effective density gradient. As a result, the lighter materials rise to the top of the cyclone and are discarded as waste. The higher density indicator minerals, including diamonds, concentrate at the lower levels of the device and leave the cyclone through an opening at the bottom.
The concentrate is then examined for diamonds using the X-ray flow sorter and grease table.