24-MMP-A4 Mine Valuation and Mineral Resource Estimation · May 2016
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
EGBC National Exam — Mining and Mineral Processing Engineering, 09-Mmp-A4 Mine Valuation and Mineral Resource Estimation, 2016-May. 3 hours duration; one handwritten 8.5×11 in reference sheet permitted (not an open-book exam); only approved Sharp or Casio calculators allowed. Question 1 is compulsory (40 marks, parts 1.1–1.6); candidates then select THREE of the six optional Questions 2–7 (20 marks each) to complete the paper.
Reference texts: Isaaks & Srivastava, An Introduction to Applied Geostatistics (variogram modelling, kriging estimators, volume–variance relations); Hustrulid, Kuchta & Martin, Open Pit Mine Planning and Design (mine valuation, NPV and cut-off grade methodology, mineable reserves); Gentry & O'Neil, Mine Investment Analysis (Canadian mining taxation, inflation and financing effects on DCF yield, smelter/refining contract terms, net smelter return); SME Mining Engineering Handbook, 3rd ed. (mineral exploration/evaluation stages, ore reserve classification, ore deposit models); CIM Best Practice Guidelines and NI 43-101 (Canadian Securities Administrators).
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.
5.1.a) 100%-equity case. With straight-line depreciation computed on historical (undepreciated original) cost and NOT indexed to inflation, the depreciation tax shield is fixed in NOMINAL dollars while revenue and operating costs both inflate. As inflation rises, taxable income rises in nominal terms even though real income is unchanged, so the EFFECTIVE tax rate on real income increases (a "phantom income" effect) – the real DCF yield therefore decreases as inflation rises, because more of the growing nominal cash flow is siphoned off as tax on a depreciation shield that itself never grows.
5.1.b) 60/40 leveraged case. Fixed-nominal DEBT interest is, like depreciation, a nominal-dollar deduction that does not grow with inflation, deepening the same phantom-income tax effect on the interest side. However, debt PRINCIPAL is also repaid in progressively cheaper, inflated future dollars – a real wealth transfer from lender to equity holder that grows with inflation and it is this effect, not the interest-deduction erosion, that dominates. Combined, the 60/40 leveraged project's DCF yield still decreases with inflation but far less steeply than the all-equity case – leverage provides a meaningful, though partial, hedge against the depreciation-erosion effect.
5.1.c) Do the effects cancel, and can inflation be ignored? The two effects (depreciation-shield erosion pushing yield down; cheap-dollar debt repayment pushing equity yield up) work in OPPOSITE directions and, for a specific combination of leverage ratio, interest rate and inflation rate, can approximately offset – some practitioners have used this observation to argue for ignoring inflation in a simplified constant-dollar analysis. This is not a safe general rule, however: the offset is exact only at a particular leverage/inflation combination, is never exact for other cost/revenue-side inflation differentials (e.g. if operating costs inflate faster than product prices), and depends on debt actually being available on fixed-nominal terms (not inflation-indexed financing). A prudent evaluator models inflation explicitly (Question 5.5 below) rather than relying on an offset that only coincidentally cancels under specific assumptions.
