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SUM710S - Surface Mining 315 - 2nd Opp - June 2022 |
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n Am I BI A u n IVER s I TY
OF SCIEnCE Ano TECHnOLOGY
FACULTYOF ENGINEERINGAND SPATIALSCIENCES
DEPARTMENT OF MINING AND PROCESSENGINEERING
QUALIFICATION: BACHELOR OF ENGINEERING IN MINING ENGINEERING
QUALIFICATION CODE: 08BMIN
LEVEL: 8
COURSE CODE: SUM710S
COURSE NAME: SURFACE MINING 315
SESSION: JUNE 2022
DURATION: 2 HOURS
PAPER: THEORY
MARKS: 100
EXAMINER{S)
SECOND OPPORTUNITY QUESTION PAPER
Mr. Privilege Shava
MODERATOR:
Dr. Mallikarjun Pillalamarry
INSTRUCTIONS
1. Answer all questions.
2. Read all the questions carefully before answering.
3. Marks for each question are indicated at the end of each question.
4. Please ensure that your writing is legible, neat and presentable.
PERMISSIBLEMATERIALS
1. Examination paper.
2. Scientific Calculator
THIS QUESTION PAPER CONSISTS OF 4 PAGES (Including this front page)
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Question 1
a) An open pit zinc mine with a head grade of 3% and a processing recovery of 77% has
the following cost structure per tonne of ore.
Item
Cost (N$)
Mining
156.73
Processing
202.86
General and administrative (G&A)
105.06
Freight, Smelting and Refining
56.81
Depreciation
89.23
The current market price of Zinc metal is US$1.23/ lb.
Required:
I. Net value per tonne of ore in N$.
[3]
11. Estimate break-even cut-off grade.
[3]
You are further required to evaluate the effect of the following:
Ill. Improved recovery of 82%.
[3]
IV. Cost escalation of 7%.
[3]
Use the following conversions for this question:
1 lb= 0.453592 kg; 1US$ = N$14.50
b) Explain the following terms:
I. Stripping ratio.
[2]
II. Overall slope angle.
[2]
c) Explain how the above terms (in part b) impact on the ultimate pit limit (UPL). [4]
d) With the aid of a diagram(s), explain the term "strip mining".
[5]
Question 2
a) You are Mining Engineer at a quarry operation where rock is supposed to be carried
from pit to the crusher. The density of the rock is 1600kg/m 3• Required hourly
production as demanded by the crusher stands at 2100tonne/h. The following shovel
parameters are provided:
Maximum loader activity per hour- 50 mins
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Bucket Size
14m3
Bucket fill factor
0.88
Loaderlnternalcharge/h
$240/h
Hauler Internal charge/h $180/h
First Bucket
0.2 mins
Each Additional Bucket
0.4 miris
On site are Cat 777D trucks with an empty mass of 64 359kg and a Gross Vehicle
Weight of 163 293kg with a permissible over and underload of 5% of payload. The
distances to be covered by the trucks in their HOR (Haul-Dump-Return} route and the
respective speeds are tabulated below:
segment
location
Distance
Speed (km/h}
1
Quarry pit
100
43
2
Haul road
550
17
3
Haul road
700
34
4
Haul road
500
21
5
Dump area
200
43
Return
45
Truck exchange time is 0.5mins. Assume an additional fixed time per cycle of 1.5 mins. Assume
the trucks return at a constant speed of 45km/h through the entire 5 segments.
Evaluate the following:
I. Number of shovels and trucks for satisfying the hourly production
requirements.
[5]
II. Cost per ton for satisfying the hourly requirement.
[5]
Ill. Number of trucks and shovels to give minimum production cost per ton. [3]
IV. Cost per ton for (iii}
[5]
V. Difference in cost, in percentage terms between the two scenarios.
[3]
VI. Make a comment on the two alternatives, cost-wise and efficiency-wise. [4]
You are provided with queue tables to aid you in answering this question.
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r
Question 3
A mining company X has recently discovered a significant offshore diamond deposit off the
coast of Namibia.
a) Explain the process leading to the discovery of the diamond deposit and identify the
factors that the company would have considered to declare the deposit mineable?
[4)
b) With the aid of a suitable diagram, advise the company on a potentially suitable mining
method to economically exploit the deposit.
[6]
c) One of the key factors in the equipment selection for the proposed offshore project is
capital cost versus Life-of-Mine. Explain this factor within the context of the proposed
mining method in b.
[5]
d) With the aid of a suitable diagram, explain Strip Mining.
[10)
General Guide: type of deposits amenable to strip mining, equipment used, production
cycle, and how it differs from other conventional surface mining methods.
Question 4
a) You have been tasked to select equipment for a new uranium open-pit mining operation.
The General Manager assigns you to give an overview of what considerations you would
make in selecting equipment for the entire operation. Highlight and explain the
considerations you would present to the company General Manager.
[5]
b) Explain in detail how the equipment selection process fits into the surface mine
optimization process, clearly outlining its role and significance within the entire mine
optimization and evaluation framework.
[5]
c) Evaluate the concept of in-pit crushing from a productivity and economic viewpoint. [5]
d) Evaluate the factors that affect slope stability in an open-pit mine, clearly outlining their
importance in maintaining slope stability.
[6]
e) State the factors one would consider in determining the following:
I. Bench height
[2]
11. Haul road location
[2]
--End of Question Paper--
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