Its good to see some robust analysis/discussion in HC again.
The difficulty Core has around its recoveries is shown in the diagram below. They have a DMS plant that is operating at least ok, if not well. DMS plants are known to have a lower size they process effectively so the fines are screened out before getting to the DMS. Core have a crushing problem whereby a lot more fines are being generated than expected. Lots of fines is not a current management competency issue. It might reflect a past management team competency issue around either the test work undertaken or choosing to ignore warning indicators from test work. Advice from ex PLS staff on how to run a blended DMS/Flotation plant won't help this problem because its primarily occurring before material gets to the concentrator.
There are three basic options available around fines:
- Fix the crushing problem so less fines are generated (Which may not be possible and crushing is already being done by an industry expert)
- Increase the crush size so that less grinding occurs to get to that crush size (less grinding = less fines)
- Adjust/implement plant that can process fines aka the flotation debate
In a larger deposit there may be the option of processing from a different area of the deposit, but that isn't an option for Core with Grants.
Core have taken the actions you would expect. They have done tests then increased the crush size which appears to have decreased fines more than its negative impact on DMS recoveries. Core have negotiated amended terms with customers enabling the delivery of a lower concentrate product. This option is feasible because transport logistics remain a tiny part of Core's cost structure. While fines prices were ok, Core also achieved some indirect recoveries from fines by DSO shipping them although that has now stopped.
One of many differences between PLS and CXO is PLS made the early decision that flotation was required. Many WA projects are finding this to be the pathway they need to follow despite its higher startup capital cost and higher operational costs. As per the media article below, from June 2018 PLS were producing a fines concentrate from flotation. PLS therefore had a more difficult commissioning exercise of both flotation and DMS however with both concentration plant options onsite, PLS then had a greater range of options available around how they presented ore to the different processes so as to improve recoveries.
https://im-mining.com/2018/06/26/pilbara-minerals-produces-first-concentrates-pilgangoora/
Pilbara Minerals produces first concentrates at Pilgangoora - International Mining (im-mining.com)
(20min delay)