Question 23 of 23: 6.4: NSV and NSR Calculation for a Copper Concentrate

Question 6.3–6.4: NSV and NSR Calculation for a Copper Concentrate (8 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

Given.

Find. NSV (per tonne concentrate); NSR at the smelter (per tonne concentrate).

Approach. Convert the payable copper grade (assayed grade less the unit deduction, applied as grade POINTS, not a dollar figure) to payable pounds per tonne of concentrate, value it at the quoted metal price for NSV, then subtract the deductions this contract actually specifies — treatment charge and transport — for NSR (no refining charge or precious-metal credit is given in this table, so none is applied).

1. Payable metal content. The unit deduction removes 1.20 percentage POINTS from the assayed grade before payment: $$\%\ \text{Cu payable}=M-D=38-1.20=36.80\%\ \Rightarrow\ 0.3680\ \text{t Cu/tonne concentrate}$$ Converting to pounds (1 tonne = 2204.62 lb): $$\text{Payable Cu}=0.3680\times2204.62=\boxed{811.30\ \text{lb Cu/tonne concentrate}}$$
2. NSV (6.3). Gross value of the payable metal at the quoted market price, before any deductions: $$NSV=811.30\times0.90=\boxed{730.17\ \text{USD/tonne concentrate}}$$
3. NSR (6.4). Subtract the treatment charge and the mine-to-smelter transport cost this contract specifies (no RC or precious-metal credit given): $$NSR=NSV-T-\text{Freight}=730.17-100.00-340.00=\boxed{290.17\ \text{USD/tonne concentrate}}$$