Ya, usually no problems with granite. However, if the kimberlite is not strong, the pillars must be nice and wide for room and pillar mining. Say a 3:1 or 4:1 aspect ratio. In other words they must be 3 or 4 times wider than they are high depending upon the depth below surface (in-situ stress levels increase with depth). The amount of ore you can take out is then a function of how wide you can make the rooms.
For instance, if the rooms are 10 metres wide and the pillars need to be 10 metres wide for stability reasons, then you are only getting 50% recovery of the geological resource. Probably better off looking at another method. The consultants will figure this out.
Likewise, you need to leave a good "crown pillar" to keep the elements out (rain and groundwater). I would suggest at least 50 metres of vertical height below surface. This ore can be tied up (not mined) for a long time.
So what is it Walt? Is the kimberlite soft or hard? As I say, I have not done any due diligence on this one so I hope I'm not giving everyone a mining lesson for no reason.
As for the capital cost, much depends upon surface soil conditions. ie. unstable tundra? Stable bedrock? etc.
Remember, all the cement, diesel, propane etc. has to come in from Edmonton most likely. Probably around $8,000 a 30T load or so. I'll stand by my $C500M estimate. This is what Echo Bay would have cost in todays' dollars.
Funny the way these projects go... the scoping study says $C200M, the pre-feasibility study says $C300M, the feasibility study says $C400M and the guy who builds it does it for $C500M!!
Gee, for a lurker, I'm not doing bad,eh? Cheers. |
