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HMT710S - Hydrometallurgy 314 - 1st Opp - June 2023 |
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n Am I BI A u n IVE Rs ITY
OF SCIEnCE Ano TECHn OLOGY
FACULTY OF ENGINEERING AND SPATIAL SCIENCES
DEPARTMENT OF MINING AND PROCESSENGNEERING
QUALIFICATION : BACHELOR OF ENGINEERING IN METALLURGY
QUALIFICATION CODE: 08BEMT
LEVEL: 7
COURSE CODE: HMT 710S
COURSE NAME: HYDROMETALLURGY 314
SESSION: JUNE 2023
DURATION: 2.5 HOURS
PAPER: THEORY
MARKS: 75
FIRST OPPORTUNITY QUESTION PAPER
EXAMINER{S) Mr. Bernard Sililo
Ms Foibe Uahengo
MODERATOR: Dr. Theresa Coetsee
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.
THIS QUESTION PAPER CONSISTS OF 4 PAGES (Including this front page)
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Question 1
[11]
1.1 Water is an important solvent in hydrometallurgy.
a) Explain why water at normal temperatures is a good solvent for ionic substances.
(2)
b) Explain why and how the salvation properties of water changes with an increase in
temperature.
c) Briefly explain the difference between hydration and hydrolysis.
(2)
i'I
i'
(2)
I:
d) Explain how water is different from other chemical liquids.
j'I I
(2)
1.2 The standard process for zinc sulphide extraction follows the 'Roast-leach-electrowinning'
route. However, there is an available leaching method that is used in zinc extraction industries
today. Briefly describe this leaching procedure.
(3)
Question 2
[8]
Using the precipitation diagram below, answer the following questions.
-,
--c :-
3-..
."3' -3
12
14
pH
a) Discusshow you would separate silver{I) ions from the solution containing magnesium(II) ions.
(4)
b) From the diagram, why do the lines for +3 ions have a different gradient than those for +2
ions?
(4)
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Question 3
[13)
A preliminary process design is required for the electrowinning of copper from strip solutions
produced by solvent extraction. As shown below, the pregnant strip liquor will be produced at a rate
of 100 m3/h and will contain 63.6 g/dm 3 of copper in a sulphate solution. The composition of the
desired spent electrolyte is shown.
Calculate,
a) The daily rate of production of copper.
(3)
b) The required acid concentration in the pregnant strip liquor. What assumptions have you
made in these calculations?
(10)
Solvent
Extraction
31,2g/dm3 Cu
198g/dm3 H S0 4
Electro-
winning
100m3/h
63,6g/dm 3 Cu
Cu
Figure 1. The solvent extraction and electrowinning circuit
Question 4
[12)
Skorpion Zinc (SZ)is one of the mines in Namibia that processes zinc and since its start till about 2019,
SZ processed the orebody as explored. Answer the following questions on zinc extraction at SZ.
a) Skorpion zinc ore is a unique orebody and could not be processed using traditional zinc
extraction routes. Explain why.
(4)
b) What is SZore deposit?
(1)
c) Given the SZ unique orebody, how would you effectively and efficiently leach such ore
deposit?
(S)
d) Write the balanced equation of leaching zinc silicate ore with sulphuric acid.
(2)
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Question 5
[9]
5.1 Discussthe advantages of roasting copper sulphide ores followed by acid leaching of the calcine.
(5)
5.2 The technologies of copper hydrometallurgy for treating copper oxide and sulphide ore and
concentrates are continuously developing and expanding. Briefly discuss the key drivers for this
development around SX-EWroute of copper processing.
(4)
Question 6
[10]
You are given a project to leach a copper sulphide ore from a newly explored mine site. The mine
stakeholders are unclear of the importance of doing mineralogical analysis before leaching begins as
they want the leaching process to commence immediately. Briefly discuss the importance of
mineralogy to present to the stakeholders.
Question 7
[12]
In an electrolysis device, an external direct- current supply is connected to two platinum electrodes
immersed in a 1.0 M CuSQ4(aq) solution at 25°C.As the cell runs, copper metal is deposited onto one
electrode and 02(g) is produced at the other electrode.
a) Sketch this cell and label the anode and cathode electrodes, also the direction of the flow of
electrons.
(4)
b) Write the balanced net ionic equation of the overall electrolysis reaction that occurs in the
cell.
(2)
c) Determine the Gibbs free energy for this reaction.
(3)
d) An electric current of 1.50 amps passesthrough the cell for 40 Minutes. Calculate the mass in
grams of the CU(stlhat is deposited on the electrode.
(3)
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Table 1: Standard reduction potential
Reduction Half-Reaction
I
F,(g)+2c--+ 2F(aq)
S,O/(aq)+2c·-+ 2SO,'·(aq)
O,(g)+4H·(aq)+4c--+ 2H,O(I)
Br,(1)+2c·-+ 2Br'(aq)
I
Ag·(aq)+c·-+ Ag(s)
I
Fc'·(aq)+c·-+ Fe'·(aq)
I,(1)+2c--+ 21·(aq)
Cu'·(aq)+2c·-+ Cu(s)
Sn'·(aq)+2c·-+ Sn'·(aq)
!
S(s)+2H·(aq)+2c--+ H,S(g)
I
2H·(aq)+2e--+ H,(g)
Sn,,.(aq)+2c--+ Sn(g)
I
v•·(aq)+c·-+ V'·(aq)
Fc'·(aq)+2c--+ Fe(s)
Cr'·(aq)+ 3c·-+ Cr(s)
Zn'·(aq)+2c--. Zn(s)
I
Mn'·(aq)+2c--+ Mn(s)
I
Na·(aq)+c·-+ Na(s)
I
Li'(aq)+c--+ Li(s)
Standard Reduction Potential (V)
+2.87
+2.01
+l.23
+1.09
+0.80
+0.77
+0.54
+0.34
+0.15
+0.14
0.00
-0.14
-0.26
-0.44
-0.74
-0.76
-1.18
-2.71
-3.04
i
--
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The Periodic Table of the Elements
1
H
Hydrogen
1.00794
3
Li
Lithium
6.941
11
Na
Sodium
22.989770
19
K
Potassium
39.0983
37
Rb
Rubidium
85.4678
55
Cs
Cesium
132.90545
87
Fr
Francium
(223)
4
Be
Beryllium
9.012182
12
Mg
Magncsium
24.3050
20
Ca
Calcium
40.078
38
Sr
Strontium
87.62
56
Ba
Barium
137.327
88
Ra
Radium
(226)
21 22 23
Sc
Scandium
44.955910
Ti
Titonium
47.867
V
Vanadium
50.9415
39 40 41
y Zr Nb
Yttrium Zirconium Niobium
88.90585 91.224 92.90638
57 72 73
La Hf Ta
Lanthanum
138.9055
Hafnium
178.49
Tantalum
180.9479
89 104 105
Ac Rf Db
Actinium Rutherfordium Dubnium
(227)
(261)
(262)
24 25
Cr Mn
Chromium
51.9961
42
Manganese
54.938049
43
Mo Tc
Molybdenum Technetium
95.94
(98)
74
w
Tungsten
183.84
75
Re
Rhenium
186.207
106 107
Sg
Scaborgium
(263)
Bh
Bohrium
(262)
26
Fe
Iron
55.845
44
Ru
Ruthenium
101.07
76
Os
Osmium
190.23
108
Hs
Hnssium
(265)
27
Co
Cobol!
58.933200
45
Rh
Rhodium
102.90550
77
Ir
Iridium
192.217
109
Mt
Mcitncrium
(266)
28
Ni
Nickd
58.6934
46
Pd
Palladium
106.42
78
Pt
Platinum
195.078
110
(269)
29
Cu
Copper
63.546
47
Ag
Silver
107.8682
79
Au
Gold
196.96655
111
(272)
30
Zn
Zinc
65.39
48
Cd
Cadmium
112.411
80
Hg
Mercury
200.59
112
5
B
Boron
10.811
13
Al
Aluminum
26.981538
31
Ga
Gallium
69.723
49
In
Indium
114.818
81
Tl
Thallium
204.3833
113
6
C
Carbon
12.0107
14
Si
Silicon
28.0855
32
Ge
Germanium
72.61
50
Sn
Tin
118.710
82
Pb
Lcod
207.2
114
7
N
Nitrogen
14.00674
15
p
Phosphorus
30.973761
33
As
Arsenic
74.92160
51
Sb
Antimony
121.760
83
Bi
Bismuth
208.98038
(277)
8
0
Oxygen
15.9994
16
s
Sulfur
32.066
34
Se
Sdenium
78.96
52
Te
Tellurium
127.60
84
Po
Polonium
(209)
9
F
Fluorinc
18.9984032
17
Cl
Chlorine
35.4527
35
Br
Bromine
79.904
53
I
Iodine
126.90447
85
At
Astatine
(210)
2
He
Helium
4.003
10
Ne
Neon
20.1797
18
Ar
Argon
39.948
36
Kr
Krypton
83.80
54
Xe
Xenon
131.29
86
Rn
Rodon
(222)
58
Ce
Cerium
140.116
90
Th
Thorium
232.0381
59 60
Pr Nd
Praseodymium Neodymium
140.90765 144.24
91 92
Pa u
Prot.ictinium Uranium
231.03588 238.0289
61
Pm
Promethium
(145)
93
Np
Nc:plunium
(237)
62
Sm
Samarium
150.36
94
Pu
Plutonium
(244)
63
Eu
Europium
151.964
95
Am
Amc:ricium
(243)
64
Gd
Gadolinium
157.25
96
Cm
Curium
(247)
65
Tb
Terbium
158.92534
97
Bk
Bc:rkc:lium
(247)
66
Dy
Dysprosium
162.50
98
Cf
C.ilifomium
(251)
67
Ho
Holmium
164.93032
99
Es
Einstc:inium
(252)
68
Er
Erbium
167.26
100
Fm
Fc:nnium
(257)
69
Tm
Thulium
168.93421
101
Md
Mc:nddc:vium
(258)
70
Yb
Ytterbium
173.04
102
No
Nobdium
(259)
71
Lu
Lutetium
174.967
103
Lr
Lowrc:ncium
(262)
1995JUPACmasses and ApprovedNomcsfrom ht1p://www.chcm.9mw.ac.uk/iup:ic/A1Wt/
masses for 107-111from C&EN,March 13. 1995.p. 35
112from h11p://www.gsi.de/zl 12c.htm_!
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