Current versus design operating costsI tried to figure out how economics of scale will play out. Leaching operation is very hard to handle,
because it obscures the sulphide operating costs. I decided to proceed by excluding leach operation
from both revenues and costs. I.e. it pays it's costs and serves sulphide operation by decreasing
strip ratio. This should be fairly conservative approach.
Q4 2009, the plant was running at 21122 tonnes per day. (note tons vs tonnes)
Mining $1.45 (on average per tonne material moved to mill, leach pads and waste dump)
Mining costs don't scale as well as milling costs, but in my opinion they should be able to do $1.25
per tonne. (guestimate based on how it usually goes). However, they are already using 100 tonne
trucks, and will use the same size equipment at 45500 tonnes per day.
Design processing costs
Leach Processing 0.61 $/ton (but would probably vary a lot month over month?)
Supergene 3.44 $/ton
Hypogene 3.05 $/ton
Q4 they treated 1.03 tons leach ore, and milled 2.14 tons supergene ore. I.e. design milling cost
would be $8.02 m. But in Q4 it was $11.68m. Milling costs are running 45% higher than designed. It's
understable, pre-feas was done 2006. But, raising throughput could cut costs about 20%.
-> $4.3 per tonne ore milling costs on average might be reasonable.
Admin costs are more or less constant. Pre-feas estimated them
.21 per tonne, but in Q4 it was
.76
per tonne ore.
.35/t should be ok to use.
Finally, estimating 31 m annual offsite costs. Which are very close to design numbers. And 0.78 per lb
copper pound produced.
It all would sum up to 1.19 /lb all in (C1) cash costs for copper equivalent pound.