There are two key pieces of information that would greatly assist understanding the Grants operation that Management are not providing.
- How much of the waste rock movement has been completed at Grants?
- Does the Grants mining plan still have a final year with unbelievably cheap ore?
While some mines will mine the cheap ore first and mining costs will get progressively higher as the mine ages, that was not the mining plan developed for the Grants deposit. The mining plan had huge amounts of waste rock being moved in the initial periods and very little in the late periods. The first period is a volume-based waste to ore ratio of 34.8:1 and that is super-high. It creates a very high cost structure and C1 that is unprofitable in anything but very high prices. Nobody tries to mine Spod at a 35:1 strip ratio, you would be nuts to do so unless prices were super high.
The only reason why Core did this was because on the volumes provided by Core in its DFS, the overall Grants strip ratio average was 16.6:1. Still high, but ok if you have a good mining contractor and process the ore efficiently. At times it is almost as if with the staff turnover Core has forgotten the structure of this mining plan and have focused purely on the here and now where a crazy cost structure does exist. That cost structure becomes even worse if you are trying to build ROM up while mining high strip ratio material. Lets for a moment consider what the financials would look like if you were to mine 22:1 material and put one part to ROM and one part to the processing plant. I'll assume mining costs are $5/t and 5.7t of ROM is needed for a ton of SC4.8.
You would be mining 46 units. 44 units of waste rock, one unit that is used by the DMS and one that goes onto the ROM. Your cost for each unit used by the DMS would be a staggeringly high A$230/t. If the DMS were using 5.7t of ROM for each unit of SC4.8 then the mining cost element of that concentrate is $1,311/t. Add on some processing and logistics costs and you could have the circa A$1,900/t prices being reported. Is this how these high figures come about? Also, if you were to mine 600kt of ore from an area with a 22:1 strip ratio requirement, at A$5/t you would be spending $69m over the period.
Lets try that with the last year of the Grants mining planYou need to mine 1,050k cubic metres of material to get 290k cubic metres of Ore. The strip ratio is 2.6:1 and there is no ROM build.
If the mining cost is $6.5/t (smaller operation, less efficient). You need to shift 3.62t of material for each ton of ore. Your cost of ROM is $23.4/t. If you still used 5.7t for each ton of concentrate (a 63% recovery rate would pull that down to 5.5t), the mining cost is A$133/t. That sort of mining cost should be profitable at US$1,000/t selling prices for SC6.0. That sort of mining cost is associated with far left on the cost curve operations like Greenbushes.
So Core management:- How much waste rock has been moved and how much is still to be moved?
- Does the Grants mining plan still have a period with super-cheap ore at the end of it?
- Forgetting the past, what is the remaining life of mine strip ratio at Grants? [aka how big is the departure from the original plan]
I have asked the last question of Core, but unsurprisingly my request was not answered (it would be commercially sensitive to tell me and not the market). Why can't Core tell the market this piece of information to assist them to help understand cost structures where mining may restart is unknown to me.
From the July 2021 DFS. Note the Total column doesn't add to the figures presented because it includes Hang Gong.
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