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A vertical ore body having a consistent width of 100 m has been excavated by the open pit method up to a depth of 100 m at a pit slope angle of 45°. The figure shows the cross section of the open pit. If the ore body is further excavated by a depth of 10 m, maintaining the same pit slope angle, the ratio of waste rock to ore is<br><img src="/images/question-image/mining-engineering/introduction-to-mining-engineering/1682335097-M2-1.3-4-24.PNG" title="Introduction to Mining Engineering mcq question image" alt="Introduction to Mining Engineering mcq question image">
A
1.2
B
2.1
C
3.0
D
3.9
Correct Answer:
2.1
Accept
Reject
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A flat coal seam of thickness (t) 3m is excavated and broken roof rock has completely filled the space created due to extraction as shown in the figure. If the bulking factor of roof rock is 1.2. the caving height (H) in m is
A
15
B
16
C
14
D
12
In an opencast mine shown in the figure below, the coal has a density of 1.4 t/m
3
. Assuming mining operation started from plane XY, the operating stripping ratio under the given conditions in m
3
/t is
A
2.32
B
2.47
C
2.56
D
2.64
Figure shows a two pulley system for hoisting a load of 10 kN. The coefficient of friction between each pulley and the rope is 0.2. The vertical and horizontal distances between the centers of the pulleys are 25m and 16m respectively. The tensions T
1
and T
2
respectively in kN are
A
6.00, 5.38
B
12.37, 11.06
C
18.74, 16.73
D
25.11, 22.41
The following characteristic curves (P, Q, R, S) pertain to rotary drilling in rock.
Title of the curve
I : Torque versus RPM
II: Rate of penetration versus uniaxial compressive strength of rock
III : Rate of penetration versus weight on bit
IV : Specific energy versus weight on bit
Match the curves with their titles
A
P-III, Q-IV, R-II, S-I
B
P-II, Q-IV, R-I, S-III
C
P-IV, Q-III. R-II, S-I
D
P-I, Q-III, R-II, S-IV
A two tonne mine car is released from the top of an incline at a height of 3m as shown in the figure. The mine car travels 45m along the inclined track and another 85m along the horizontal track before coming to rest. The specific rolling resistance of the, car in N/tonne is
A
0.226
B
0.326
C
0.526
D
0.126
The following information is provided for an ore deposit:
Number of waste blocks = 10
Number of ore blocks = 5
Volume of each waste block, m
3
= 600
Total cost of waste handling per m
3
= Rs. 100
Tonnage of each ore block = 400
Total cost of ore handling per ton = Rs. 150
Sale price of ore per ton = Rs. 500
The net cash flow of mining the deposit in lakhs of rupees, is
A
3.4
B
2.5
C
1.0
D
0.8
A mining project comprising of A, B and C activities is scheduled for 90 days at a cost of Rs. 1200 million. The manager of the project decides to reduce the time for completion of the project to 85 days. The decision was taken after 45 days, The minimum cost of the project in million rupees after crashing 5 days is
A
100
B
1300
C
1475
D
1825
From the stress-strain diagram shown below, the tangent and the secant moduli of elasticity in GPa are
A
4.0, 2.2
B
3.3, 2.3
C
3.3, 1.5
D
4.0, 1.5
An ore block of length 30m and height 20m having an average width of 1.5m with sharp boundary walls is mined with a minimum mining width of 2m. If the tonnage factors are 3 t/m
3
for ore, 2 t/m
3
for wall rock and average grade of ore is 10%, the diluted grade of ore mined in percent is
A
7.5
B
7.84
C
8.18
D
8.52
A pumping station in a mine has 4 pumps, P
1
, P
2
, P
3
and P
4
which are connected functionally in parallel configuration as shown in the figure. The individual reliability of the pumps P
1
, P
2
, P
3
and P
4
are 0.80, 0.90, 0.85 and 0.95 respectively. For an effective dewatering operation in the mine denoting system success, at least three pumps should be in operation. The reliability of the system is
A
0.19
B
0.93
C
0.99
D
0.58
