For one thing, I believe Ventana is actually as close to production as Greystar is.
With all due charitable respect to GSL, they still have metallurgical difficulties to solve.
Their technical reports state that while they have strategies they are entertaining for dealing with it, there is no completely accepted method of recovering the maximum amount of the gold contained in the mineral body. In other words, metallurgical testing is a work in progress.
Whilst they have started a feasibility study, and declared measured indicated and inferred resources, with rather lower grade at first blush than their 2005 drilling seemed to indicate, they have not actually figured out as far as I know the exact contribution of the high grade ore shoots. If they don't really know this contribution by detailed structural drilling, then they cannot decide what their recovery is, as you can't just heap up a pile of ore of indeterminate grade and then after having leached it for 6 months decide your recovery, as you don't know what you had to start to begin with. If the grade is X then on type of recovery applies economically, if the grade is Y then another might apply. No sense coming to a methodology decision before you know grade, and percentage recovery of gold in actuality by the different processes.
Fort Knox in Alaska runs profitably on a grade of 0.25 grams per ton. Full milling. Not heap leach. The full milling option makes sense to GSL as they can more easily deal with the sulfides by roasting or autoclave in plant with good recoveries. At high tonnage costs are acceptable.
Examples of large in plant ore recovery proceess are the ore bodies at Malartic or Osisko and Detour Gold. Very large plants are envisioned at comparable grades to GSL. Their ore is however not refractory and does not require secondary treatment.
An example of bio heap leach that sort of worked and proves the concept to a degree is Brewery Creek. There is even the possibility of a hybrid recovery process where one ore is leached in plant and the other in heaps as befits the material.
Heap leach is more attractive from thru put and capital cost perspective, so if they can get it to work with acceptable recoveries, they should keep that option in mind right to the end. But for heap leaching to work acceptably they have to do bio-heap leach, and tackle the sulfides ore, as right now the recovery in sulfide or "fresh ore" is abysmal with heap leaching. Bulk recoveries that they quote do not impress me, as the unknown component of losses in the ore due to high grade uncertainties cloud the issue and possibly give a lie to the figures. There may be much more gold to recover than they are calculating. I think they are several bulk tests and 2 years away from getting an satisfactory answer here.
Ventana with triple to quintuple the grade and having underground ore, has no such problem in that it will most probably be a near surface underground mine. That dictates in plant leaching after fine grind. The ore grade can stand it and thus are available many economic ways of dealing with refractory gold that may exist. I admit metallurgy studies have yet to be done.
Ventana has some exceptional intersections of high grade gold. Notable are 5.83 grams per ton over 94.5 metres. This is not that deep, perhaps 1200 feet. Nobody is saying you have to go all the way down there to get at the orebody. That is just the depth they drilled it to.
With Ventana being at early stages, and GSL being a late stage project, the comparison is difficult to make. Ventana is more a stock play than GSL. GSL has to pump to get their stock up to a price that will befit a financing that puts them in production. I think they could be 2 years away to start and 3 years from production. Ventana might be neck and neck with them if they play it right. It makes zero sense for a burgeoning play like Ventana to join forces with an old dog like GSL. Babies and elderly gentlemen do not play in the same crib.
Not that GSL is shabby.
Most mines are built, not found and GSL is a classic example of making the metallurgy to make the mine. There have been many similar stories from Flin Flon to Kerr Addison. Not much noise was made about teh considerable structural and metallurgical work done in bring them to feasibility. It took some doing to unravel the Kerr Orebody. Far harder than GSL. And the metallurgy of the Kerr Mine, while based on a mature approach was bedeviled by graphite and talc. They solved it in house with proprietary methods in flotation and roasting. I am privy to much of their chemistry solution. Flin Flon involved the first cyanide recovery circuits in a massive sulphide ore. That made the economics of that massive copper ore body and the economics of Manitoba as well. Possibly without Flin Flon and the Mills and Crowe solution to their cyanide problem there may have been no Snow Lake.
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