RE: Stark27 Oct 2023 10:54
Hi Sprint,
That's correct; the ore is sorted to improve grades before grinding and then flotation. (A few more stages, but that's the gist)
Surprisingly there’s not been much discussion on the feed, sorting and grinding circuit upgrades from STARK. There’re significant and will have a meaningful impact on performance and economics.
The problem was getting consistent grind size from the mill, and it struggled with the moisture content of the grinds re-feed circuit.
Stark has solved the milling problems and, in addition, added a Hydrosizer (Good piece of kit) and, even better, a UV sorter.
The UV sorter was made in collaboration with another company and is the first of it’s kind. It runs in sequence with the XRT sorters - The results are proving to be excellent.
For perspective, average feed grades are generally 1-1.5%, this can then be floated off to be SC6.
STARK indicates that the sorter is proving material in the range of 3-6%. I.e. SC3 to SC6. That’s world-class standard feed grades from such a small plant. Impressive stuff. I’m sure people are going to recognise the significance of this in hindsight.
Those grades are saleable as is. (+ Mag sep etc). This is the first run of the new sorters and mill, which has been successful, so the good news for holders is that prem is producing (Subject to RNS) saleable grade spodumene. It's not SC6, but it's still a valuable commercial product.
Now there’re optimising the float circuit to get SC6 (5.5%). The float circuit floats off the mica first and then floats the spodumene, it takes time to find the correct operating parameters, as every ore body is different—aeration rate, regnant mix, feed rate and, agitation rate, etc.
The inconsistent feed sizing from the last mill led to problems in the Mica float - It’s difficult to adjust for the right chemical density/composition for too considerable a variation in particulate size - This should now be resolved.
The rest is all about tuning. But as confirmed by Stark it’s producing spodumene. So, it’s just about time now. The float plant is from an excellent supplier.
It’s just a matter of time now; hopefully, no more unforeseen items in the short term.