Discussed below is GL1's initial DMS works for Marble Bar released today. These results will most likely be improved but at present historical work ADV commissioned has GT1 being in better shape than GL1 is currently regarding metallurgical results. Core lithium is also explored for its historical Metallurgical results. GT1's early results are better than Core's (disc holder in Core).
In doing this I've also managed to explain to myself why GT1 was having recovery rates above those of existing operators (which seemed odd). These high 80% and even low 90% recovery rates would appear to be from crushed and screened material. Some of the lithia content is lost as fines in the crushing process. In different place you will see inclusive of fines recovery rates and in other places exclusive of fines recovery rates. Stats from in production companies include losses as fines.
GL1 DMS on Marble BarSo today GL1 released some "positive" initial DMS results re Marble Bar. Key details were:
- 200kg bulk sample from recent drill cores with a head assay result of 1.38% 1.38% Li2O and 0.93% Fe2O3
- Crushed to P100 3.35mm and screened to 0.85mm
- Magnetic separation added as a step
- Grade achieved of 6.08% Li2O and 0.59% Fe2O3 with a 50.1% lithia recovery (Not that flash!!)
- The text is a little unclear on this, but I think a subsequent flotation circuit on the non-DMS successful material and fines had a 58% recovery
- Combined DMS and Floation circuit recovery was 76% Li2O at a 5.9% grade (and Fe2O3 was back up to 1%)
- The share price of GL1 was up, but only modestly on the announcement
Lets now look at the bulk GT1's Seymour DMS results of 15 Nov 2017 reported by ADV:
- 500kg bulk sample of course spodumene particles up to 6.0mm with an average head grade of 1.29% Li2O (so the head grade being used is slightly lower than what GL1 used. No Fe2O3 grades were noted in this 15 Nov announcement)
- The chips were hand broken (I'd have preferred machine broken as it may more closely match production conditions)
- Particle sizes of 0.5mm to 6mm (so the largest pieces were bigger than GL1's and the same as early Core work)
- The recovery rate was 86.46% using feed of 0.5mm to 6.0mm at 1.37%. Fines were 13.54% at 0.84%.
- At a grade of 6.05% there was a DMS recovery rate of 85.58% from the 0.5mm to 6.0mm material (Dropping the grade to around 5.5% to 5.8% would improve this recovery figure but by how much is unclear from the announcement)
- Conservatively assuming no recovery from the fines material, there would be an overall 74% recovery of Lithia (86.46% * 85.58%) before assuming any recovery in relation to fines or minor improvement from DMS crush sizes, pressures.
- Potential would appear to exist to increase this further through fines processing and tweaking settings.
- This would mean that 1Mt of 1.17% North Aubry resource could be expected to generate over 144kt of 6% Spod. That production size would be an 8 year mine life if the 7.8Mt (North Aubry only) if North Aubry existing inferred could be convered to Measured and indicated.
- Current drilling is on-track to expand this 7.8Mt at North Aubry.
Context from Core
I've included four snapshots of Core lithium recovery tables/announcements.
- From 30 March 2017, Core used DMS+Flotation to get 82.39% for 6% (but like GT1's 85.6% this figure excludes the recovery losses that occur through fines)
- Through changing the max size among other things, an Aug 2018 Core announcement "improved" this to 79% for 5.5%. The improvement was that an expensive flotation circuit was avoided. This figure is more directly comparable to GT1's 6% @ 86% recovery
- By the DFS of April 2019 the recovery rate was 71.9% for 5.5% grade. I'm presuming the drop was through fines recovery losses being factored in.
- By the Final DFS of July 2021 the recovery rate was 71.7% for 5.8%. Clearly this was sufficient for the project to progress to construction. GT1's early results are above this.
