24-MMP-A5 Surface Mining Methods and Design · December 2018
Question 14 of 27
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Notes on this paper
Paper: Surface Mining Methods and Design (09-MMP-A5), National Exam, December 2018 — 20 pages, compulsory Question 1 (40 marks, parts 1.1–1.8) plus THREE of five optional Questions 2–6 (20 marks each) normally constitute a complete paper. As a study resource, this solution answers Question 1 in full AND all five optional Questions 2–6.
Reference texts: Hustrulid, Kuchta & Martin, Open Pit Mine Planning and Design (3rd ed.) — truck-shovel match factor, dragline stripping geometry, capital cost indexes, open-pit scheduling; SME Mining Engineering Handbook (3rd ed.) — equipment costing, mine dewatering, cost-index escalation.
Given. The dragline and overburden specifications used through Questions 3.4–3.9:
Given data — dragline & overburden specifications
Dragline
Value
Tub diameter
20 m
Operating radius
90 m
Positioning factor
75%
Rated stacking height
12 m
Rated digging depth
35 m
Overburden / pit
Value
High-wall angle (from horizontal)
63°
Coal face angle (simplified)
90° (vertical)
Spoil pile slope (angle of repose)
35°
Spoil pile swell factor
0.25
Depth of overburden
25 m
Pit width
40 m
Coal seam thickness
3 m
Find. Distance from the highwall edge to the dragline centerline, and the resulting maximum stacking distance from the highwall edge, at 75% positioning.
Check — positioning is taken here as the centerline sitting 75% of tub diameter INTO the pit side of the highwall edge (maximising digging reach across the 40 m pit, well inside the 90 m operating radius), with spoil stacked on the OPPOSITE (back) side of the centerline. This is the interpretation that keeps the machine’s reach comfortably covering the 40 m pit width and is the standard convention for maximum-reach side-casting; the exam figure that would fix this convention explicitly is not part of the extraction.
Maximum stacking distance from the highwall edge. With the centerline 15 m into the pit side, the reach available on the spoil (back) side is the operating radius less that offset: $$d_{stack} = R - d_{ce} = 90 - 15$$ $$\boxed{d_{stack} = 75\text{ m}}$$
Fig. S3.4 — dragline positioning: centerline 15 m from the highwall edge (into the pit); spoil-side reach 75 m from the edge.
