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MEHRAN UNIVERSITY OF ENGINEERING & TECHNOLOGY

REGULAR EXAMINATION OF 2ND TERM 23RD-BATCH (FULL TIME EVENING)

POSTGRADUATE DIPLOMA OF POSTGRADUATE STUDIES IN (MINING ENGINEERING)

(UNDER EXTERNAL EXAMINERS SYSTEM) 0F 2011.

OPEN PIT MINE PLANNING AND DESIGN

Dated:13 12 2011 Total Time Allowed 03 Hrs Max: Marks: 75Attempt Any FIVE Questions. All questions carry equal marks.

1. (a) Determine the Breakeven cutoff grade from the Figure 1, as shown below: and add

the Breakeven stripping ratio axis to this graph.

Figure 1: Net Value Vs Ore Grade Grpah(b) Calculate the area of steeply dipping ore body, as shown in Figure 2, using segment end

points. Coordinates of points are shown in Table 1.

Figure 2: Cross section of ore body showing 17 end points.Table 1: Showing the coordinates of segment end points as shown in Figure 2.

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Point X Y Point X Y

1 5500 680 9 5305 1110

2 5488.5 760 10 5406 1100

3 5453.5 760 11 5419 1100

4 5442 840 12 5523 1073

5 5407 840 13 5558 1065

6 5399.1 896 14 5667.7 766.8

7 5379 896 15 5666.6 760

8 5298 1112 16 5631.5 760

17 5620 680

2. Explain step wise procedure of Lerchs-Grossmann 3-D approach with the help of an example as

shown below in Figure 3, using arbitrary tree algorithm. Weights of nodal points are given below:

X1=X2=X3=X4= -4

X5 = X6 = 10

Figure 3: Showing the two level nodal points for Lerchs-Grossmann approach

3. Explain the objectives of production planning. Differentiate between short term and long term

planning. Express planning commandments proposed by Couzens.

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4. (a) Derive an equation for the determination of reach factor of a dragline using the geometrical

parameters as shown below in the figure:

(b) In a level terrain, determine the maximum height of highwall that a dragline can strip without rehandling, usingthe following information:

Operating radius of dragline (OR)= 47 m

Tub diameter (d) = 11 m

Dragline positioning (P) = 0.75d

Spoil angle of repose () = 37o

Highwall angle of repose () = 74o

Width of slice (W) = 15 m

Coal seam thickness (T) = 1.22 m

Swell factor (S) = 30%

5. (a) Discuss the objectives and importance of geotechnical investigations for the design and

planning of an open pit mine.

(b) What is the role of haul roads in surface mining? State the influencing factors for the

design and layout of haul roads.

6. (a) What is the criteria of ore body description? Explain the role of reserves and ore grade

in the calculation of open-pit life

(b) Give a detailed account of the stability conditions of a pit slope. In what circumstances a

particular part of a slope is likely to suffer a failure?

7. Determine the minimum number of front load shovels required for removing the

overburden in an open pit mine using the following information:

Annual production = 36,163,613 m3

Estimated annual operating time = 6,120 hours

Cycle time = 55 seconds

Bucket size = 9.94 m3

Swell factor = 0.50

Dipper fill factor = 0.80

T H E E N D