Rio Tinto has completed a 10-hole bulk sample at Star Diamonds’ Star-Orion South project in Saskatchewan using a Bauer trench butter rig. Credit: Rio Tinto
SASKATOON – Rio Tinto has completed its 2019 bulk sampling program at Star Diamond’s Star-Orion South diamond project, 60 km east of Prince Albert, in central Saskatchewan.
Using novel technology – a trench cutter sampling rig normally used in civil engineering projects that has been adapted for use at the project – the company has collected 8,271 wet tonnes of material. Each trench took between 9 to 17 days to complete, and reached a depth of up to 251.1 metres.
George Read, Star Diamond’s senior vice-president exploration and development, said in a press release that the new sampling technology has the potential to revolutionize future bulk sampling and mining of kimberlites like those at Star-Orion South.
“This ambitious sampling program required significant time to assemble all the components on site, but once it commenced the trench cutter has operated efficiently and successfully, recovering a large bulk sample from the Star kimberlite,” Read said.
An onsite bulk sample processing plant is in the final stages of construction. Once completed, it will be commissioned using kimberlite from Orion South in a 2009 underground bulk sample program. Final diamond recovery will be done off site at a secure facility.
Rio Tinto is earning up to a 60% interest in the project under an agreement signed in 2017. The major will earn its first 51% in Star-Orion South once it completes the first two phases of work: a 10-hole bulk sampling program within the first three years, and then another 10-hole program (or $18.5 million in spending) within the following 18 months.
The Star and Orion-South kimberlites contain global resources of 66 million carats (193 million indicated tonnes grading 15 carats per hundred tonnes and 57 million inferred tonnes grading 11 cpht in Star; and 200 million indicated tonnes grading 14 cpht and 72 million inferred tonnes grading 7 cpht in Orion South).
Although they are very low grade, the kimberlites are known to host high-value, rare, Type IIa diamonds, as well as large stones.