An innovative talk in the Geometallurgy session at Xplor 2019.
Montréal, Queen Elizabeth Hotel, October 23th 2019, 3:00 PM

https://xplor.aemq.org/conferenciers/rejean-girard/

Did you know that most gold mines in Québec produce less ounces of gold then what is thrown in the tailings by Canadian Malartic? And still, we invest hundreds of millions to find new mines! May we think out-of-the-box and change our focus a little? Although gold recovery in mills is excellent, typically above 90%, it still means that 10% of the gold is accumulating in the tailing! And any gain in recovery adds directly to the profits of the producer! So, let's take our mineralogist's eye and our exploration arsenal to investigate what is going on in mills... one gold grain at the time since mills are just factories that separate gold grains. In order to improve mills efficiency, it is essential to gain understanding on what is happening to the gold grains and how they are lost to the tailings, which is dictated by its deportment. Gold does not only occur as grains of free native metal, it also can be micronized, in sulfosalts, non-liberated, encapsulated in sulfides or silicate, refractory as solid solution in sulfides, ionic in solution, etc. But how do we measure that, since we are dealing with grades in the order of 50 ppb with an ubiquitous nugget effect? It's a real technological challenge!

Conventional approaches for deportment measurement are based on replicating in laboratory the process used in the mill. Sorry, but mills are more efficient than laboratories, that merely replicate the issues of the mill. At such low grades, representativeness is a serious issue that makes such measurement imprecise, costly and time consuming. A battery of new approaches that circumvents the nugget effect was thus developed, based on grain counting just as for glacial sediment exploration methods. Backed by counter-intuitive mathematical modeling, deportment of gold at very low grade can be measure precisely. The technique being fast and cost effective, it can be implemented as a routine to track mill's operations, notably to have quick feedback when the mill faces a recovery issue.

The technique is to be presented as a talk in the « Geometallurgy » session at Xplor 2019, the hub of mineral exploration in Québec. Furthermore, our ARTPhot automated gold grain counting technology will be in display at our booths (#314 and #315). The Québec Mineral Exploration Association is eager to welcome you at the Queen Elizabeth Hotel, October 23nd-24th. See you then!

« There are those who follow the rules... and those who define them! »

Back scattered electron image of micrometer size gold-grains recovered from the tailings of Goldex Mine, Val-d'Or. Notice the smallest grain is about 300 nanometres in diameter!