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PPD710S - Process Plant Design - 1st Opp - June 2022 |
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nAmlBIA unlVERSITY
OF SCIEnCE Ano TECHnOLOGY
FACULTYOF ENGINEERING
DEPARTMENT OF MINING & PROCESS ENGINEERING
QUALIFICATIONS: BACHELOR OF ENGINEERING IN METALLURGY & CHEMICAL ENGINEERING
QUALIFICATION CODE: 08BEMT & 08BECE LEVEL: 8
COURSE CODE: PPD710S
SESSION: JUNE 2022
DURATION: 3 HOURS
COURSE NAME: PROCESSPLANT DESIGN &
ECONOMICS 315
PAPER: THEORY
MARKS: 100
EXAMINER:
MODERATOR:
FIRSTOPPORTUNITYQUESTION PAPER
Mr. Thomas Moongo
Prof. Vusimuzi Sibanda
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. Calculator and stationery.
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THIS QUESTION PAPER CONSISTS OF 7 PAGES (Including this front page)
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SECTIONA
[30 marks]
Question 1
[5 marks]
Design a simplified P&ID for a water tank with a tank level control system. Clearly show all
relevant instruments and equipment required to control the tank level.
Question 2
[5 marks]
How would you describe a process flow diagram (PFD)?Give at least four (4) features of the
PFD and four (4) aspects that should be considered for characterizing process streams.
Question 3
[5 marks]
During metallurgical testwork the ore must go through mineralogical and chemical analysis.
Write the following ore characterization techniques in full.
a) QUEMSCAN
b) SEM
c) AAS
d) ICP- OES
e) ICP- AES
Question 4
[5 marks]
By means of a table, give five (5) factors you would consider when making a decision whether
to apply a jaw crusher and a gyratory crusher onto your design. The table should compare the
two crushers.
Question 5
[5 marks]
Give names of appropriate models that you can apply when designing the following unit
processes or equipment listed in the table below by completing the table.
Unit process/equipment
1.
Model name
(a) Particle size distribution
2.
(b) Sizing of screens
3.
(c) Hydrocyclone
4.
(d) Sedimentation velocity
5.
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Question 6
Write the following economics abbreviations in full and define them.
a) TVM
b) DCF
c) CAPEX
d) EBITDA
e) MIRR
[5 marks]
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SECTION B
[70 marks]
Question 1
[10 marks]
The designed green hydrogen pilot plant is expected to experience the cash flows shown in the table
below. As a design engineer working on the green hydrogen project you were tasked with determining
the profitability index of this project at 5% and 10% discount rate. What criteria would you use to
conclude on which discount rate will be acceptable and what is your conclusion?
Year
0
1
2
3
4
5
Cashflow (N$}
-10 000
2 000
2 000
2 000
2 000
5 000
Question 2
[10 marks]
All design engineers should be able to communicate with other technical experts by using appropriate
diagrams. For the following operations, develop an appropriate block flowsheet with at least five (5)
major unit processes each of the following operations:
(a) Dundee Precious Metal Tsumeb copper smelter that produces blister copper.
(b) AfriTin's Uis Tin Mine concentrator.
(5 marks]
(5 marks]
Question 3
[10 marks]
Chemical and Metallurgical Engineers with an entrepreneurial mindset have established a Process
Design Company. These design engineers are interested in winning a tender for designing the entire
gold processing plant for the Twin Hills gold deposit that was recently discovered by an exploration
company named Osino Resources northeast of Karibib town. You have been requested by the project
manager to design a detailed process flow diagram (PFD)for the entire gold ore processing plant that
will produce gold bars. The design should have at least ten (10) labelled unit processes or equipment,
all the streams should be clearly shown, and standard equipment icons should be utilized.
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Question 4
[10 marks]
Namib Lead and Zinc Mine is considering undertaking experiments to improve process
efficiencies. First, they are considering determining the minimum quantity of a sample
required for metallurgical testwork for a lead ore assaying 5% Pb which must be routinely
sampled for assayto a confidence level of ±0.1% Pb, 95 times out of 100. Galena is essentially
liberated from the quartz gangue at a particle size of 150µm. Assume that the sample will be
collected during crushing to a top size of 25 mm. The mean density of Galena and Quartz is
7.50 g/cm 3 and 2.65 g/cm 3.
Question 5
[10 marks]
Uis Tin Mine is assessing if they should replace the existing mill motor after they installed a
newly designed mill. In this case, a jaw crusher product is milled such that 80% passes a 500-
micron sieve down to a size at which 80% passes an 88-micron sieve. A 5hp motor is sufficient
for the required throughput and for grinding. If the requirements are changed after the new
mill was installed such that grinding is now done to 80% passing a 125-micron sieve, but the
throughput will be increased by 50%, is the existing motor sufficient to operate the mill?
Assume Bond's equation applies.
Question 6
[10 marks]
Kombat Copper Mine seek advice from process design consultants regarding the below
proposed design modification in their processing plant. The rod mill is fed at the rate of 20tph
with dry solids (density 2900 kg/m 3). The cyclone feed contains 35% solids by weight and size
analysis on the rod mill discharge, ball mill discharge and cyclone feed gave the following:
Circuit equipment
Rodmill discharge
Ball mill discharge
Cyclonefeed
Analysisby weight
26.9%
4.9%
13.8%
Sizeanalysis
+250µm
+250µm
+250µm
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Ore Feed
Water
Cyclone
Underflow
Overflow
Ball mill
Flotation
As an expert in process plant design, advice Kombat Copper Mine management on what
should be the volumetric flowrate of the feed stream to the cyclone. Draw a sketch of the
problem and show all your work.
Question 7
[10 marks]
Rosh Pinah Zinc Mine is considering re-designing its flotation circuit due to mineralogical
changes observed in the ore. As a student who is well versed with the design of flotation
circuits you were given a responsibility to derive the following:
(a) Derive the first-order flotation rate equation for batch flotation.
[5 Marks]
(b) Derive the equation for the number of similar size cells (N) in a continuous flotation bank
given residence time (r), total recovery (R) and flotation rate constant (k).
[5 Marks]
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Listof Equations
Power (P) = K(J)pLD2·5 ~Sin0
Ncrit
C = fglm
Pip= fiP + W}:j":J.bijSjwi -SiwiW
i>l
Cash flow
Present value = (l+t ·)n
42.3
N. ----
mt -
Y= 100G)m
(R = Q 60LTvW(2LMIN + LT)
1)
M=-
Cd 3
sz
P = E (kWh/t) x F (t/h)
R = 1 - (1 + kr)-N
F= U + 0
(100) loglog R = mxlog(x) + c
m =-1[(-aa1-
Ff= Cc+ Tt
a)r + at]
E= Es(l - £2) ( MB )
MB +Ms
Screen
area = -----~-~--Feed rate (tph)
Standard screen capacity
(t/hm 2 )
E= lOWi(-
1
-
-
1
- -)
__________________
THE END______________
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