just some thoughts in response to poster talantless
1. Very hard with no clean friable cut between the quartz lode and the hard dolerite/basalt host. I.e. no alteration halo. If most of the gold is on the contact (which it generally is within antitaxial veins) then you run the risk of excess dilution or missing most of the gold.
how do you come to the conclusion that there will be excessive dilution, couldnt they blast at closer centres with a smller charge so there is less disturbance of ore but still fractured sufficnetly for a digger to remove
2. The control/s on the au mineralisation was not simple. Having bashed around down there for a while it was not apparent what was controlling the higher grades.
not sure why that is a problem the ground controll drilling should delineate the ore body
3. Angle of the ore body is 45 degrees. A miners nightmare (especially in OP) meaning excess dilution up to 100% (do the trig)
Agreed if it was a UG mine and cut and fill mining was difficult due to being too far off vertical, but this is opencut where all the ore and country rock needs to be removed.
4. Very difficult, if not impossible, to be able to blast ore and waste separately = more dilution. Also small pits = large heave. Are they planning pre-splits? If so extra cost.
I dont know what pre-splits are sorry nor what large heave is
5. There are old workings and knowing the old boys they took the best bits. Unfortunately the records are never good and you never know when you will come across an old ballroom which has taken the honey. I very much doubt these have been (or could have been) accounted for in the modeling. Void = to probe drilling = extra cost.
6. Very hard drill and blast + hard wear and tear on the gear (especially on the digger) = extra cost.
Cant see the ore being too hard to blast would it not be oxide and transition laterite ore as previoulsy they were talking heap leach which wont work on harder sulphinde ore
7. Small pit means if you do double shift you will be mining ore on night shift (which I would NEVER allow). No double shift = extra cost.
cant see how that is relevant as guessing it is a campaign mining scenario with NAV picking ore up when it has surplus capacity only
8. Small pit = small gear/small team means high cost/bcm. Day costs add up pretty quickly too. Gear standing idle still costs!
The pits are not that small would think they can still use triple 7 CAT dump trucks and 120 ton diggers
There is no way IMO that you can mine this without suffering excess dilution and ore loss and cost blow outs.
The biggest costs to NME are the haul and treat. If you are hauling as far as they are and the dirt turns out to be heavily diluted the grade a lot less than expected they will do their dough. How are they going to establish the grade before they haul? Dump sampling is notoriously inaccurate. If the choose to crush before they haul that is an extra cost.
THey will campaign mine through bronzewing sure its a big plant that needs large baches of ore to treat but low grade ore is far easier to determine grade from on the ROM than narrow vein UG mines
Why haul at all if the gravity recovery is high anyway and you are planning to heap leach. Gravity circuits are pretty cheap to set up cf the cost of hauling 200+km and toll treating.
Agreed but why use a gravity circuit just heap leach the oxide on site
Trouble with gravity circuits is mass recovery can become an unachievable target.
just some thoughts I am not a mineing professional
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