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UDM711S - Under Ground Mining 315 - 1st Opp - June 2022 |
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n Am I B I A u n IVE Rs I TY
OF SCIEnCE Ano TECHnOLOGY
FACULTYOF ENGINEERINDAND SPATIALSCIENCES
DEPARTMENTOF MINING, MECHANICALAND PROCESSENGINEERING
QUALIFICATION : BACHELOROF ENGINEERING {BEng) - MINING ENGINEERING
QUALIFICATION CODE: 0SBMIN-05
LEVEL: 7
COURSE CODE: UDM711S
COURSE NAME: UNDERGROUND MINING 315
SESSION: JUNE 2022
DURATION: 2 HOURS
PAPER: THEORY AND CALCULATIONS
MARKS: 100
EXAMINER
FIRSTOPPORTUNITYQUESTION PAPER
Mr. Tshivute lipinge
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.
THIS QUESTION PAPER CONSISTS OF 4 PAGES (Including this front page)
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Question 1
There is a vertical ore deposit as indicated on figure 1. Vertical shaft was designed to be sunk in
position 1, 2 as indicated in the diagram. Compare and contrast these two scenarios and suggest the
preferred scenario. Support your preference. (8 marks)
Sh.:ift
Shi!h
Position 1
µosition 2
~,.,,----.~~, tC'.,,,r
II
\\
II
\\
11
\\
\\
II
1st level'
'\\
2nd level
~~------'-I
"11
1,
Bottom mining level
-------
,..,...~''" '", ""7
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Subsidence angle
_____
_
Layout of vertical shaft.ain vertical ore body
Figure 1. Diagram showing the lay out of vertical shaft positions 1 and 2 o-in vertical orebody
Question 2
The block development work is an important part of underground mine development to successful
mine the orebody. What are the factors you should take in consideration while developing main level
layout development? (8 marks).
Question 3
Many factors influence the decision of selecting a shaft or decline/ramp to access an underground
mine. Describe some of these factors that influence your decision of selecting the access to your
orebody. (8 marks).
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Question 4
Given the following data for the design of friction sheave hoists; calculate the total cycle time and
skip capacity and its weight.
Two balanced skips, tower mounted hoists
Production rate= 8000 tons/day
Working time = 3 shift/day
Shaft distance= 1200 m
Headframe height= 35m
Skip load = 0.67 live load
Load time= dump time= 6 sec
Hoisting speed = 12.5 m/sec
Acceleration = retardation = 2.3 m/s 2
(12 marks)
Question 5
As a mining engineer you are required to develop a drift of about 600m along the orebody with a
Jumbo drill. The drift (tunnel) dimensions are as follows:
a) 5.Sm x Sm
b) Drill steel 4.5 m
c) 3 shifts
d) Actual drill meter per round 4 m
e) Efficiency of 85 %
f) Specific gravity of rock is 2.5 tfm 3
Calculate the development meters per day and per week? Estimate how long will you develop the
tunnel, the number of tonnages to be hauled per day, week, for the entire length of 600m? (10
marks).
Question 6
As a mine planning engineer, describe the six dimensions that are vital in characterising the work
conditions of your equipment selection? (12 marks).
Question 7
A mine has a zinc deposit that is being mined with a target of 20 000 tonnes of ore per month, with
an open stope mining method. The stope is on average 15m wide and inter-level spacing of 45m.
Longitudinal mining is being executed with the length of the stope being around 150m long. Rings are
planned with a burden of 1.Sm and spacing 2.m. If blasting is done once every week to meet
production and specific gravity of 2.5 can be applied.
a) Draw the section of the mining method (4 marks)
b) Compute stope Volume (2 marks)
c) Compute the stope, and the ring tonnages (3 marksj
d) The number of rings that must be blasted every week (3 marks)
e) How long does the stope last before it is mined out? (3 marks)
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f) The cross cut to the loading bay is 1 km long and it takes 10 minutes cycle time for LHDwith
3.5 m3 bucket to travel. A 20-tonne truck takes 30 minutes cycle time to haul material to
surface. Would the two pieces equipment meet the production target if you have three shifts
of 8 hours? (12 marks).
Question 8
Discussthe mining method shown in the picture below, in sub areas of suitability of mining method,
how development, and production is undertaken. (15 marks)
JSECTION
Ii '
I I SECTION 2-2'
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End of question paper.
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5/6/22, 10:20 AM
Queuing Model, Single Server Formulas
Queuing Model, Single Server Formulas
J_ p _ Prob [system is.
0
-
empty (idle)
1
µ
L = average number
q in the queue
µ(µ - 1)
L = average number = 2
in the system
µ -- A
W = average time=
A
4 in the queue µ(µ - l)
W = average time = l
in the system µ - A
Note:
}¥ is the arrival rate.
µ is the service rate.
web.pdx.edu/-stipakb/download/PA557/QueuingModelSingleServerFormulas.html
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