Reference no: EM133026957
ENGIN3503 Surface Mining Operations and Equipment - Federation University
1. Explain the terms
a) Overall pit slope angle
b) Mineral resource
c) Cut-off grade
d) Charge density
2. An open pit mine employs ANFO at a density of 0.85 g/cc as its explosive. Given the following details, determine the blasthole spacing
• Bench height is 12m.
• Burden and spacing of blastholes are the same, i.e. B = S.
• The specific gravity of the rock is 2.5.
• The powder factor is 0.6 kg of explosive per m3 of rock.
• Hole diameter is 200 mm.
• Stemming column length is 20 times of hole dia and subdrill is 10% of the bench height.
• Blast face is inclined at 15° from the vertical and the blastholes need to be parallel to the face.
If ANFO has a cost of $1250 per tonne, what will be the cost of explosives per tonne of rock?
3. Why is the individual bench slope angle steeper than the stack slope angle, which is steeper than the overall pit slope angle?
4. Explain various deciding factors related to choice of opencast mining over open pit
5. Discuss the concept of stripping ratio and how haul road gradient, bench, stack and overall slope angles affect it
6. Illustrate with a suitable diagram, how waste overburden and orebody geometry dictate the choice of surface mining method
7. A discontinuity is found fully developed from the toe to the bench surface on a 20 m high slope, slope angle 61°. The discontinuity (frictional angle 31° and cohesion 18 kN/m2) is planar and its strike is parallel to the slope face with a dip 38°. Determine the factor of safety in case of a planar slope failure assuming drained conditions. Unit weight of the rock is 2.5 t/m3.
8. What is meant by "break-even stripping ratio" and what factors would you consider when you need to determine its value?
9. What is the difference in opencast, open pit and quarry mining?
10. Briefly describe frontal cut, drive-by and stop-and-reverse parallel operations with suitable diagrams.
11. Explain the following terms with the aid of sketches, as they apply to an open-pit operation;
(a) Overall slope angle
(b) Bench stack slope angle
12. A dragline is to be selected to remove overburden at a rate of 395,000 cubic meters per month. If it will be scheduled to operate 720 hours per month with an operating efficiency of 0.80, its bucket factor is 0.85 and its cycle time is 54 seconds, what should be the size of its bucket?
13. Describe briefly how the operational life of a mine can influence the choice of transport equipment. Refer in your answer to a new open-pit mine and a deep open-pit mine that is near the end of its production lifetime.
14. Briefly describe the applications of the below equipments in surface mining. What are the major factors affecting the selection?
a) Mining shovel,
b) Dragline
c) Bucket wheel excavator
d) In-pit crusher
e) Rail haulage
f) Conveyor belt
15. Explain the importance of slope angle in economics of surface mines by some examples and diagrams.
16. Illustrate bench width. Why should we provide a safety bench? What are the factors affecting the safety bench width?
17. What is the pit limit? Describe a procedure to determine pit limits.
18. Estimate the unit profit in mining and processing a 0.85% copper ore deposit if the selling price of copper in concentrate is $1.76/kg and overall unit costs are $5.5/ton. Overall recovery is 80.5%. Calculate the cut-off grade of the Copper deposit.
19. A 20 m bench is required to be blasted for a large face shovel. The hole diameter is 250 mm and stemming is set to 20 times the hole diameter. The burden has been set to 6.0 m and the spacing set to 7.0 m to provide best fragmentation. The charging plan is to use a toe charge of 3 m of 1.3 density heavy ammonium nitrate fuel oil (ANFO) and a cap of 1 m of 1.2 density heavy ANFO. The remainder of the column is ANFO (density= 0.83). Calculate the powder factor for this blast. State any assumptions made.
20. Assume an underground mining cost of $22.5/ton ore for an orebody. Assume open pit mining costs at $0.0028/kg ore removal and $0.0035/kg waste removal. Determine the stripping ratio for an open operation that results in break-even cost differential between the two mining methods
21. What is the purpose of pit limit optimisation and typical computer based optimisation methods?
22. What are typical mine wastes? Describe measures to safely contain mine wastes.
23. Briefly describe :
a). Objectives of production planning;
b). Taylor's mine life rule;
c). Sequencing by nested pits;
d). Production scheduling.
Attachment:- Surface Mining Operations and Equipment.rar