24-MMP-A5 Surface Mining Methods and Design · December 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-Dec. 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 seven parts 1.1–1.7); a candidate then selects THREE of Questions 2–7 (each worth 20 marks).
Reference texts: Hartman & Mutmansky (eds.), SME Mining Engineering Handbook, 3rd ed. (dragline stripping systems, truck-shovel productivity, mine dewatering, mine cost estimation); 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); 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; Mular, A.L. & Poulin, R. (1998), CapCosts: A Handbook for Estimating Mining and Mineral Processing Equipment Costs, CIM Special Volume 47 (parametric open-pit capital-cost formulae used throughout Question 7).
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.
1.6.1 – Simple side casting. The dragline sits on the original ground surface (grade), digs the full overburden depth in a single pass, and casts the spoil directly into the adjacent previously-mined-out strip – the basic, single-machine method suitable only where the overburden depth is shallow enough that one pass, from grade, reaches both the coal floor and the required spoil-pile stacking height (Question 6.5–6.6 shows numerically what happens when it is not).
1.6.2 – Advanced bench mining. A secondary machine (dozer or scraper) pre-strips a bench of the UPPER overburden ahead of the dragline, so the dragline itself only has to dig and cast the LOWER portion in its single pass – this reduces the total volume (and hence stacking height) the dragline itself must cast in one lift, allowing a total overburden depth beyond what simple side casting could handle with the same machine (directly the fix Question 6.7 recommends once side casting is shown inadequate).
1.6.3 – Extended bench mining. The dragline works from a bench raised ABOVE the original pit floor (created either by the pre-stripped material of 1.6.2 or by leaving a shelf cut into the overburden), which extends both its effective digging reach and its effective dumping height beyond what is achievable sitting at grade – allowing an even greater total overburden depth to be handled than advanced bench mining alone, at the cost of an extra bench-preparation pass.
