24-MMP-A5 Surface Mining Methods and Design · May 2014
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
EGBC National Exam — Mining and Mineral Processing Engineering, 09-MMP-A5 Surface Mining Methods and Design, 2014-May. 3 hours duration, closed book; one hand-written 8.5×11 inch reference sheet and an approved Casio or Sharp calculator permitted. Question 1 is compulsory (40 marks, all six parts 1.1–1.6); a candidate then selects THREE of Questions 2–6 (each worth 20 marks).
Reference texts: Hartman & Mutmansky (eds.), SME Mining Engineering Handbook, 3rd ed. (dragline stripping systems, truck-shovel productivity, mine cost estimation — the primary reference throughout this paper); Hustrulid, Kuchta & Martin, Open Pit Mine Planning and Design, 3rd ed. (block-model economics, floating/moving-cone algorithm, the Lerchs–Grossmann graph-theoretic pit-optimization method, annual push-back scheduling); Kennedy, B.A. (ed.), Surface Mining, 2nd ed., SME (dragline range-diagram geometry, stripping methods); Lerchs, H. & Grossmann, I.F. (1965), “Optimum Design of Open-Pit Mines,” CIM Bulletin, 58, 47–54.
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.
Spotting is the manoeuvre of positioning an empty truck under the shovel’s dipper/bucket swing arc so loading can begin — the truck reverses into place, guided by the operator or a spotter, so the bucket can dump into the box with minimal swing angle and no double handling. Double back-up loading uses two truck positions on either side of the shovel (or two queue lanes), so a second empty truck backs into its spot WHILE the first is finishing loading, cutting the shovel’s idle (queue/spot) time between trucks to near zero. Drive-by (or “fly-by”) loading has the truck approach FORWARDS past the shovel and stop already correctly positioned (no reversing manoeuvre at all), which is fastest when road/bench geometry allows a forward approach at the loading point but needs more room and a well laid-out blast pattern/bench width to execute safely.
All three are ways of minimizing the shovel’s non-productive (spot/queue) time between successive truck loads, which is exactly the quantity that determines the match factor and cycle-time calculations of Question 5 below.
Truck drive types. Off-highway mining haul trucks in typical use are (1) mechanical (diesel-mechanical) drive — a diesel engine drives the wheels through a torque-converter and multi-speed mechanical transmission, favoured on smaller/mid-size trucks for lower first cost and simpler maintenance; and (2) diesel-electric drive (AC or DC) — the diesel engine drives a generator/alternator that powers electric wheel-motors, favoured on the largest ultra-class trucks because it delivers full rimpull from a standing start, handles grade and payload variability more smoothly, and scales to higher gross vehicle weights than a mechanical driveline can practically manage.
