24-MMP-A4 Mine Valuation and Mineral Resource Estimation · Undated paper
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, undated sitting. 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 (parts 1.1–1.5); candidates then select THREE of the five optional Questions 2–6 (20 marks each) to complete the paper.
Reference texts: Isaaks & Srivastava, An Introduction to Applied Geostatistics (variogram modelling, anisotropy, volume–variance relations); Hustrulid, Kuchta & Martin, Open Pit Mine Planning and Design (mine scheduling, NPV/valuation methods, stripping-ratio economics); Gentry & O'Neil, Mine Investment Analysis (Canadian mining taxation, CCA classes, smelter/refining contract terms, net smelter return); SME Mining Engineering Handbook, 3rd ed. (mineral exploration/evaluation stages, ore reserve classification); Guilbert & Park, The Geology of Ore Deposits (volcanogenic massive sulphide genesis); 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.
4.3.1–4.3.3 — Trucking cost trends with depth. As a pit deepens, haul distance and lift both increase, directly raising fuel consumption, tire wear (tire cost scales strongly with haul-road grade and cycle time) and cycle time per tonne — so ore trucking cost per tonne rises through the mine life, tracking the increasing depth of the ore benches; waste trucking cost per tonne follows the same physical driver but on the waste-bench depth profile, which in a push-back sequence often precedes the ore trend (waste is stripped ahead of ore, so waste haul depth/cost typically rises somewhat earlier in the schedule than ore haul depth/cost); and the total mining cost curve (ore + waste) is the sum of both, generally rising most steeply during the peak pre-production and early-production stripping years when waste tonnage (and depth) is greatest relative to ore, then moderating in later years as the stripping ratio typically falls once the pit has reached its planned waste benches. On purchase vs. rental of used trucks: renting/leasing used haul trucks avoids large up-front capital outlay and lets fleet size flex with the mine's own rising/falling truck-hour demand through the schedule (useful given this cost is explicitly non-constant), but rental typically costs more per operating hour over the truck's life and offers less control over maintenance standards/availability than an owned fleet — purchase is generally favoured once the mine's long-term truck-hour demand is well-established and stable enough to justify the capital commitment.
4.4.1 — Stripping ratio and constant truck-hour planning. Per the question's own stated range, the annual stripping ratio for this operation varies from a minimum near 0.5:1 to 1:1 (low-cost periods where waste barely exceeds, or is less than, ore tonnage) up to a maximum of roughly 3:1 (heavy pre-production/early-production stripping years). Knowing this range lets the planner deliberately counter-balance the schedule: since total truck-hours are driven by combined ore+waste tonnage and haul distance, a planner facing a low-stripping-ratio year (spare truck-hour capacity relative to the fleet) can pull forward waste stripping from an upcoming high-ratio year into the current low-ratio year, smoothing the truck-hour (and hence fleet-size and labour) requirement across the mine life rather than sizing the fleet to the single worst (3:1) year and leaving it under-utilized in low-ratio years — this is precisely the "waste ahead of ore, but not more than necessary" balance the question's own scheduling rules are built to enforce.
