24-MMP-A4 Mine Valuation and Mineral Resource Estimation · May 2017
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, 2017-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 five optional Questions 2–6 (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, smelter/refining contract terms, net smelter return, transportation logistics); SME Mining Engineering Handbook, 3rd ed. (cost-estimating relationships, mineral exploration/evaluation stages, ore reserve classification); Evans, An Introduction to Ore Geology and Guilbert & Park, The Geology of Ore Deposits (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.
(a) Stoppages. Smelter contracts include force majeure and stoppage clauses covering both parties – a mine-side stoppage (strike, equipment failure, natural disaster) that interrupts concentrate deliveries, and a smelter-side stoppage (furnace rebuild, labour action, environmental shutdown order) that interrupts receiving/processing. Terms typically specify notice periods, whether minimum tonnage commitments are suspended or merely deferred, demurrage/storage cost allocation for concentrate that cannot be delivered or received, and, for extended stoppages, a right for either party to seek alternate delivery/off-take arrangements without breaching the contract.
(b) Assaying rules. The contract specifies the sampling protocol (mechanical sampling of each lot per an agreed standard, e.g. ISO or ASTM procedures), which laboratory(ies) perform the umpire/referee assay, the analytical method for each payable and penalty element, and the moisture-determination procedure (since payment is on a DRY-weight basis) – all designed to give both mine and smelter confidence that the tonnage and grade used for payment genuinely reflect the lot shipped.
(c) Price fix date/time/location. The contract specifies WHEN (a defined quotational period, e.g. the average of LME/COMEX prices over the month of, or a month following, arrival/delivery) and WHERE (LME cash settlement, COMEX, or another named exchange) the metal price used for final settlement is fixed, since concentrate price participation exposes both parties to price risk over the shipping/processing timeline – the mine typically has an option to select or "price-fix" within a defined window to manage that exposure (analogous to provisional vs. final pricing in Question 6.2 below).
(d) Assay dispute resolution. If mine-assay and smelter-assay results diverge beyond an agreed tolerance (a "split" or disagreement), the contract specifies referral to a mutually-agreed independent UMPIRE laboratory whose result is binding within a further tolerance; unresolved commercial disputes beyond assay splits are typically referred to commercial arbitration (e.g. ICC or LCIA rules) under a named governing law and seat, rather than ordinary domestic litigation, reflecting that smelter contracts are frequently cross-border (a BC mine shipping to an Asian or European smelter) and both parties prefer a neutral, specialized, faster forum than the courts of either party's home jurisdiction.
(e) Blending/mixing concentrates to avoid demurrage. Smelters often contract with several mines simultaneously and BLEND multiple mines' concentrate lots in port storage or in transit to build full shipload lots, avoiding costly vessel demurrage (charter penalty for a ship waiting idle at berth) that would result from any single mine's production being too small or too irregular to fill a vessel on its own schedule. This benefits smaller producers (who individually could never economically charter a full bulk carrier) but requires careful contractual allocation of blended-lot assay results back to each contributing mine's own tonnage share, and clear rules on whose concentrate chemistry (impurity/penalty elements) governs if blending affects overall lot quality.
