Let’s take a look at the GRG (gravity recoverable gold) tests. The GRG test is going to give you information about the total GRG content in the ore and the size distribution of the GRG. So how do we get that? You’ll see here, there’s a multi-stage test. We’ve got a nominal coarse crush. We’ve got a first gravity concentration step and we’ve got a grinding step, then a second gravity concentration step and a grinding step and a third gravity concentration step. So why do we do this? If we were only going to do, let’s say this part, the final grind to the final grind size and a gravity concentration step, at that point, all we would get is this: the gravity recoverable gold content of the ore at this nominal grind size, which is fine.
But with only that, we lack information about the size distribution of the GRG. We’d be missing out on this information here, which is very important to the modeling of the circuit. So when we do the three steps, we actually build a release curve that gives us information about the size distribution of the GRG. This can also be done with a mineralogical study. It’s more theoretical and less empirical because you can’t always be a hundred percent confident about how the gold will grind at a given size. It can tell you the size of the particles, but it won’t necessarily tell you whether or not they’re actually going to get released and separated at these various size ranges. Both are very useful. But ultimately if we’re trying to predict gravity recovery, we want to be doing a GRG test. So what does that give us?
This gives us the size distribution of the GRG. And here’s just an example where we’re seeing the different amounts of GRG at different size ranges. And we use this information. So this information here to then make a partition curve that talks about, or that informs us about how the cyclone is going to perform at retaining gold and retaining particles.
If you found this video interesting, please visit minerals.seprosystems.com to find the extended video series, as well as additional shorter clips, addressing specific points around gold recovery for milling circuits. Thanks very much for watching.