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MPC711S - Mineral Separation Process 314 - 1st OPP - JUN 2023 |
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n Am I BI A u n IVER s ITY
OF SCIEnCE
TECHnOLOGY
FACULTY OF ENGINEERING AND THE BUILT ENVIRONMENT
DEPARTMENT OF CIVIL, MINING AND PROCESSENGINEERING
QUALIFICATION: BACHELOR OF ENGINEERING IN METALLURGY, CHEMICAL ENGINEERING &
MINING ENGINEERING
QUALIFICATION CODE:
08BEMT /08BECE/08BM EG
LEVEL: 7
COURSE CODE: MPC711S
COURSE NAME: MINERAL SEPARATION PROCESSES
314
SESSION: JUNE 2023
DURATION: 3 HOURS
PAPER: THEORY
MARKS: 100
EXAMINER(S)
FIRST OPPORTUNITY QUESTION PAPER
Dr Clement Kwasi Owusu
MODERATOR:
Prof. Godfrey Dzinomwa
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.
PERMISSIBLE MATERIALS
1. Examination paper.
2. Non-programmable calculator
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Question 1
(25Marks)
Rosh Pinah ore sample was floated using the Magotteaux laboratory flotation to
produce lead and zinc concenh·ate. The outcome of the laboratory flotation test after
assaying is presented in the Table below. Calculate;
i. the recovery of Pb in copper concentrate
(5 marks)
ii. the recovery of Zn in zinc concentrate
(5 marks)
iii. the tonnage (tph) of the lead concenh·ate
(5 marks)
iv. the tonnage (tph) of the zinc concenh·ate
(5 marks)
v. the tonnage (tph) tailings
(5 marks)
Sh·eam
Feed
Pb concenh·ate
Zn concenh·ate
Tailings
Throughput (tph)
150
-
-
-
Pb(%)
5.7
50.3
0.2
0.15
Assay
Zn(%)
4.3
2.1
60.7
0.10
Question 2
(20 marks)
A comminution circuit comprising of three crushers, a mill and hydrocyclone for a
gold processing plant is presented in the figure below. Per the plant design, 600 t/h
of material at a size of 80% passing 50 mm goes through the primary crushers.
1
\\QI
Primary
Crusher
l,lill
Crusher
6
I
Overflow
5 Hydrocyclone
Tertiary
Crusher
Underflow
z. If the reduction ratios for the primary, secondary and tertiary crushers are 5,
3.5 and 1.5 respectively, determine the product size for each crusher. (6 marks)
ii. What is the mill product size (in microns) if the energy required to grind the
600 t/h of material is 8219.204kWh and the work index of the ore is 14.8 kWh/t.
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(Assume that cyclone underflow has the same size as the tertiary crusher
product)?
(10 marks)
ill. If the circulating load is 25%, estimate the mass for cyclone overflow and
underflow.
(4 marks)
Question 3
(26 marks)
a. Briefly explain the impact of the following on screen performance
z. Percentage near mesh particles
(3 marks)
zz. Moisture content of feed
(3 marks)
m. Feed rate
(3 marks)
b. Mention two areas in minerals processing where hydrocyclones are widely
used as a classifier
(4 marks)
c. Mention two advantages of dense medium separation
(5 marks)
d. Calculate the mass of water in tonnes required to be added to 48.2 tonnes of
ferrosilicon compound to make a slurry of pulp density of 2.92 t/m 3. Assume
the density of ferrosilicon compound is 7.0 t/m 3 and that of water is 1 t/m 3·
(8 marks)
Question4
(29 marks)
a. Explain the terms rougher cell, scavenger cell and cleaner cell as applied in
flotation
(9 marks)
1. A single cell in a given bank of flotation cells gives a Copper recovery of
45% for a residence time of 5 minutes. Find the number of similar sized
cells in a continuous flotation bank that would give a total recovery of
93%.
(6 marks)
b. Explain the subaqueous deposition method as applied in tailings management.
(4 marks)
ii. Mention 3 possible causes for tailings dam failure.
(6 marks)
c. Explain the relevance of gravity take-up pulley in conveyor belt system
(4 marks)
THIS QUESTION PAPER CONSISTS OF 3 PAGES (Including this front page)
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