b. What does it depend on?
c. What has an impact on it?
a. SR measures the relative depth
b. Stop mining when you stop making money
* Value of ore (UVO) is equal or less than the sum of:
* cost of mining (UCM),
* cost of waste removal (UCW), and
* “other costs” (UCO)
ESR = [UVO - (UCM + UCO)] / UCW
c. Interpretation:
* how many units of waste can be removed for each unit of ore before you stop making money
What Are “Other Costs”
a. Costs borne in relation to this property
* Cost of discovery and exploration
* Or cost of acquisition
* Permitting and other costs
* Cost of infrastructure and development
b. Minimum acceptable profit
* Shareholders expect a return
* Consider that you have other alternatives in relation to spending money
SR: Definition of Pit Limit
Slope Angle & Pit Limits
Interest Rate & Pit Limits
SR & Underground Mining Cost
SR & Open Pit Mining Cost
Note: Mining Cost Changes!
So,…
How deep / far will
we mine this one?
What is the value
of ore?
Does grade has
to be considered?
a. Unit cost of surface mining is
* Waste at $1.50 per ton
* Ore at $2.00 per ton
b. Unit cost of underground mining is $15/ton
c. Unit value of ore is $20/ton
d. Other cost of mining (“profit”) are $2/ton
___________________________________________________________
Define the depth at which u/g mining should be considered
Define the depth at which you should stop mining
Other Considerations
a. BESR and ESR depend on economics
* unit value of ore
* unit cost of mining waste, ore, other
b. Economics do change
c. The results are valid only if these changes are insignificant
d. Significant changes must trigger re-evaluation of the deposit