Star Diamond Corporation recently announced that Rio Tinto Exploration Canada Inc. (RTEC) has commenced the processing of bulk samples from RTEC's trench cutter program at the Orion South Diamond Project in Saskatchewan, Canada. These bulk samples, estimated by RTEC to be approximately 8,271 wet tonnes, were collected in 2019 and are stored on-site in approximately 6,848 cubic metre bulk bags.
Star Diamond currently expects that all or substantially all of the bulk samples collected during 2019 will be processed through to final diamond recovery and reported over the balance of calendar 2020, provided that there are not any unexpected material delays in this process including arising from COVID-19 issues.
The on-site bulk sampling plant (BSP) was fabricated by Consulmet of South Africa. The BSP uses X-ray transmission (XRT) sorting technology to recover any large diamonds present (6 to 25 mm). All the 0.85 to 6.0 mm kimberlite fraction is then processed through a DMS cyclone to prepare a diamond-bearing heavy mineral concentrate for the recovery of the 0.85 to 6.0 mm diamonds. A secondary crushing circuit, using a high-pressure roll crusher, aims to maximise the liberation of smaller diamonds from the kimberlite. Star Diamond has been advised by RTEC that it is has completed commissioning of the BSP. The mineral concentrates produced by the BSP are expected to be shipped, on an ongoing basis, to an off-site facility for final diamond recovery and reporting of such recovery to Star Diamond and RTEC.
The preliminary economic assessment for the Star Orion South Project estimates that 66 million carats of diamonds could be recovered in a surface mine over a 38-year project life, with a Net Present Value (7%) of $2.0 billion after tax, an Internal Rate of Return of 19% and an after-tax payback period of 3.4 years after the commencement of diamond production.