The pre-strip is dead money. Crushing rock to get at the minerals is not; you aren't treating waste in this regard, you are treating ore to get a benefit.
Typically, mining can cost around US$5 per bank cubic metre (US$1.80/t) roughly; crushing through a 10Mtpa plant would be around US$8-12/t, depending on the rock. As you say, there are tough rocks (BIF, quartzite, jaspillite) and then there are not so tough rocks (oxide gold ores, etc). I would say Kvanefjeld would be moderately hard, certainly it would get up toward the top end of the range, some of these igneous rocks can be quite robust indeed. However, this will all come out in the PFS.
The other thing to note here is that GGG is investigating a phosphate float process; this could remove the need for a pressure alkaline leach process (as done by RISO in the 80's) which can be, to put a blunt point on it, a bit of a Murrin murrin if its not done properly.
The phosphate float would produce a REO-phosphate-U mineral concentrate. This would then be dissolved in acid (HCl-HSO4) and the dissolved materials treated essentially similarly to the proposed flowsheet over at ALK. Note here that ALK and GGG and LYC and ARU are using ANSTO-CSIRO technology for solvent extraction and concentration of REE's from acid solutions; the technlogy isn't exactly off-the-shelf but the ANSTO-CSIRO processes are cutting edge. The aim would probably be to produce a LREE and a HREE concentrate.
The process involves getting the uranium and thorium out of solution first. The thorium would be stabilised as it is, in large quantities, basically worthless right now. The uranium would be sold as oxide.
This is all straightforward because the Kvanefjeld ore is silicate rock; silicate minerals are not going to float in the phosphate colelctor. The silicates are dense, insoluble, solid.
Clays such as at Mt Weld, are soluble, forming a slush. They are impermeable, hydrophyllic (ie; reactive with all sorts of chemicals and solutions) etc. The LYC process involves a pressure leach, which is the only way to dissolve the REO's out from the clays.
So I think that Kvanefjeld has some advantages in this regard. The key will be the liberation point for the REE-U minerals, the point to which they need to crush the rock to achieve separation of the ore phase from the gangue. If the rock hasd coarse minerals, if it's tough it will not require much energy. if the ore phases are very fine, it will require much more energy. But one there, any flotation process which is effective will basically see the ore minerals removed from the 10Mt of waste efficiently and delivered to a hydromet plant somewhere in the world.
The main criteria is: will this crushing cost more than the value of the metals in the rock? Very unlikely.
GGG Price at posting:
46.5¢ Sentiment: Hold Disclosure: Held
