Link for Mount Weld Mineral Resource and Ore Reserve Update 2015 (dated 5 Oct 2015)
https://www.lynascorp.com/Shared Documents/Investors and media/Announcements and media/2015/151005 Ore Reserves and Resources 1481136.pdf
In the table entitled "SUMMARY OF THE ORE RESERVE UPDATE", there is a key change to the economic cut-off grade assumption. For the 2012 estimates, a COG of 4% was used for CZ and LI ores while a 7.5% COG was used for AP ore. For the 2015 estimates, a single COG of 4% was used for all ores.
Lynas has been setting aside the fluoride-containing apatite (AP) ore, saying it will "require modifications to the existing flotation circuit". I recently read that fluoride can interfere with effective flotation (
https://www.researchgate.net/public..._of_Fluoride_on_Hydrometallurgical_Operations), already a challenging part of the beneficiation of Mt Weld ore. Currently the flotation stage slurry is heated with diesel (40% of diesel consumption), so this is also an expensive step. Not saying modifications will make it more expensive, but I'm still surprised that they chose to use the same COG for all ores.
Suffice to say just a bit of study makes it evident why they are setting the AP ore aside.
That said, in the November 2017 Significant Drill Intersections at Mt Weld announcement (
https://www.lynascorp.com/Shared Documents/Investors and media/Announcements and media/2017/Lynas ASX Significant Intersections 28 Nov 2017 rev 7.pdf), the Table shows several thick intervals of AP ore under the thinner CZ/LI that grade better than the 4% cutoff., so
AP ore is a BIG PART of the future of Lynas. I recently reviewed a 2015 paper out of the Colorado School of Mines on the beneficiation of Mt Weld apatite ore and it was not productive. Hopefully
we will hear more about how they are advancing with the flowsheet in the near future.
It will be interesting to see how they handle the COG issue in the next update. My guess is that if they can retain "more than 25 years" of reserves at 4%, they won't change it.
The 2015 Update gave 680,000 tons proved REO in the pit design and stockpiles about which they said: "The Ore Reserves represent
more than 25 years of economic, continuous operations based on the estimated production of 22,000 tonnes per annum REO of finished products": 680,000/22,000=30.9 years.
The August 2017 D&D gave a "CLD Reserve Update 2016 (Reserve cut-off grade 4.0% REO )", not otherwise published, of 648,000 tons: 648,000/22,000=29.5 years.
Oddly enough, in the period between the 2015 Update and the "2106 D&D Update", the March 2017 Intro to Lynas Presentation stated "Central Lanthanide Deposit, the highest grade operating Rare Earths mine in the world with a current operating LOM JORC
reserve of 20+ years". Just kind of curious why they didn't repeat the "more than 25 years".
(
https://www.lynascorp.com/Shared Documents/Investors and media/Announcements and media/2017/170323 Introduction to Lynas Presentation.pdf)[/BCOLOR]
They've definitely significantly extended the AP ore depth in this lastest drill campaign, so the LOM is a matter of what COG they use and just how many holes exceeded their past expectations. Until they actually start processing AP ore, however, ...
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