Materials Production;
energy used and carbon emitted T. G. Gutowski
2.83/2.813
2
Readings
1. Exergy Accounting, Five Metals Industries,
(Ayres, Ayres and Masini, 2006)
2. Ellingham Diagrams
3. Thermodynamics of Separation (Materials
Separation and Recycling, Ch 4 Gutowski 2011)
4. Scale/Improvements (Gutowski, Sahni, Allwood,
Ashby and Worrell, 2013)
3
Outline
1. Exploration and Mining
2. Smelting (liquid metal) – Iron (Fe)
– Aluminum (Al)
– Copper (Cu)
– Gold (Au)
3. Liquid metal to sheet
4. Efficiency improvements
5. Prices, saturation and new materials
4
World Energy and Carbon
IEA 2010
5
The Role of Materials in
Manufacturing
Final Energy Carbon Dioxide
6
What’s in the crust
7
Diverse Sources of Uranium
Chapman & Roberts
8
What’s at the mine
Chapman
9
“McKelvey Box”
10
QuickTime™ and a decompressor
are needed to see this picture.
Gold ~ 250 GJ/kg
Ashby 2009
11
Geo-physical
processes
Mining &
concentrating
Materials
production
Crustal composition
Concentrated ore
Pure ore
Pure metal/mineral
Other inputs
Other inputs
Other inputs
Exergy Analysis
gives us the minimum
work for Mat’l Prod
See Thermodynamics of
Separation
Separate slides, and “Materials
Separation and Recycling”, TG Ch 4
14
For Ideal Mixtures
Bmixture Ni bi RT0 Ni ln xi
Bmixture (N1 1)b1 Ni2
bi RT0(N1 1)ln x1 RT0 Ni2
ln xi
Bmixture
B’mixture
B1
Wmin = - RT0lnx1
15
“Separation”
wmin T0R xii1
n
ln xi
16
))xln(NxlnN(RTW)N(
mini 1210
))1ln(ln)1(( 210
)1(
min1 xNxNRTW
N
wmin, 1 T0R(ln1
x1
)
“Extraction”
17
Extraction from the crust: Fe2O3
Extracting Fe2O3 from x 1.3x103(crust) to x 1
exo ToR ln
1
1.3x103
exo 298.2K 8.314
J
molK ln
1
1.3103 16.5
kJ
mol
Note: R = k Navo (Boltzmann’s constant X Avogadro’s number)
18
Extraction from the crust: Gold
Extracting Au from x 1.36x109 (crust) to x 1
exo ToR ln
1
1.36x109
exo 298.2K 8.314
J
molK ln
1
1.36 109 50.6
kJ
mol
Szargut’s Table updated by Rivero & Garfias Energy (2006); was 50.5
19
“Sherwood Plot”
20
Chapman and
Roberts ‘83
21
Cost Scaling for Metals
kv mp cv > kc mp, or kv > kc/cv
where
kv is the market value of the target material ($ per kg of target material),
mp is the total mass of ore processed (kg of ore),
cv is the concentration of the target material in the ore (kg of target
material per kg of ore), and
kc is the cost of processing the ore ($ per kg of ore).
22
Grübler 2004
23
energy requirements for mining and
milling, possible future trends
Chapman and Roberts p 113 & 116
underground ~ 1000/g (MJ/t metal)
open pit ~ 400/g (MJ/t metal)
24 Gutowski, Sahni, Allwood, Ashby, Worrell, 2013
Importance of Dilution
25
Eart
h’s
Cru
st
Compound
Formula Mass
Composition
Silica SiO2 59.71%
Alumina A12O3 15.41%
Lime CaO 4.90%
Magnesia MgO 4.36%
Sodium oxide Na2O 3.55%
Iron(II) oxide FeO 3.52%
Potassium oxide K2O 2.80%
Iron (III) oxide Fe2O3 2.63%
Water H2O 1.52%
Titanium dioxide TiO2 0.60%
Phosphorus
pentoxide
P2O5 0.22%
Total 99.22%
Density ≈
2.70g/cm3
26
CO2 from Materials Production
• Reduction of oxides with carbon
2Fe2O3 + 3C 4Fe + 3CO2
2 Al2O3 + 3 C 4 Al + 3 CO2
• Calcination of limestone in cement
production
CaCO3 + heat CaO + CO2
27
28
Gutowski, Sahni, Allwood, Ashby, Worrell, 2013
However, most CO2 comes from fuel use
29
Smelting (Liquid Metal)
1. Iron - carbon reduction
2. Aluminum - electrolytic process
3. Copper - sulfide ores & recycling
4. Gold - the effects of dilution
refs Ayres 2006 and Mudd 2007
30
Iron: Important oxide ores
Hematite: Fe2O3
Magnetite: Fe3O4
Sources: http://en.wikipedia.org/ &
http://resourcescommittee.house.gov/subcommittees/emr/usgsweb/materials/images/imgTaconite.jpg
Taconite
31
32
Hibbing MN taconite mine
34
Blast Furnace
Source: http://www.ssabox.com/news/Imagebank/blast%20furnace4.jpg
35
Iron Blast Furnace
Materials required:
1. Iron Ore
2. Carbon (coke is used both as fuel and reducing agent).
3. Hot air (hot enough to ensure combustion of the fuel).
4. Flux (removes earthy matter – turns into slag)
5. Slag (combination of calcium carbonate, silica, alumina and other impurities).
Source: http://www.yourdictionary.com/images/ahd/jpg/A4blfurn.jpg
36
Reactions taking place in the furnace:
• 2 C + O2 2 CO (1300 °C)
• CaO + SiO2 CaSiO3 (1200 °C)
• FeO + CO Fe + CO2 (800 °C - 1000 °C)
• CaCO3 CaO + CO2 (800 °C - 1000 °C)
• CO2 + C 2 CO (800 °C)
• Fe3O4 + CO 3 FeO + CO2 (600 °C)
• 3 Fe2O3 + CO 2 Fe3O4 + CO2 (450 °C)
37
Steel Exergy (US)
Ayres, Ayres and Masini, 2006
38
Steel Summary (US)
Ayres, Ayres and Masini, 2006
39
Aluminum It is the most abundant metal (7% of the earth’s crust)
but one of the more energy intensive metals to refine
Aluminum occurrence:
Bauxite : Al2O3·2H20 Cryolite: Na3AlF6
+ many silicates such as clay: H2Al2(SiO4)2·H20
Sources: http://en.wikipedia.org/ & http://www.musee.ensmp.fr/mineral//1021x.jpg
40
Aluminum Production:
1. Bayer Process: obtain Alumina (Al2O3) from Bauxite.
A. Extraction: dissolve oxides with hot
solution of NaOH.
Al(OH)3 + Na+ + OH- Al(OH)4
- + Na+
B. Precipitation: reverse of above, but
controlling crystal formation.
Al(OH)4- + Na+ Al(OH)3 + Na+ + OH-
C. Calcination: water is driven off Al(OH)3
to form alumina (aluminum oxide).
Al(OH)3 ---> Al2O3 + 3 H2O
Source: http://www.world-aluminium.org
41
2. Hall-Heroult Process (Electrolytic Reaction).
Source: http://www.world-aluminium.org
Prebake Cell
A. Al2O3 is dissolved in molten
cryolite (Na3AlF6)
B. As the current passes
through this mixture, (4-5
volts, 50,000-280,000
amperes) aluminum ions
reduce to molten aluminum
at the cathode, and oxygen
is produce at the anode
reacting with carbon to
produce CO2.
2 Al2O3 + 3 C 4 Al + 3 CO2
Prebake
Anode
42
Aluminum Exergy (US)
Ayres, Ayres and Masini, 2006
43
Aluminum Summary (US)
Ayres, Ayres and Masini, 2006
Main Ore Types for Copper
globally 90% sulfides, 10% oxides
Sources: http://en.wikipedia.org/
Cu2S: Chalcocite Cu20: Cuprite
Cu2CO3 (OH)2: Malachite
CuFeS2: Chalcopyrite
(50% of Copper Production)
45
Source: http://encarta.msn.com/media_461533479_761561391_-1_1/Open-Pit_Copper_Mine_Utah.html
Open-Pit Copper Mine, Utah
46
Chuquicamata, Chile
47
drilling rig in underground mine in
the Głogow area of Poland C
opper
concentr
ations in t
his
are
a a
re a
bout
2%
48
Copper Ore Grades in the US
49
Historical Costs for Copper
Tilton, 2003
50
Głogow* Copper Smelter
*pronounced Gwogov
51
Copper Smelting Process
Source: http://encarta.msn.com/media_461533478_761561391_-1_1/Production_of_Copper.html
52
1) Copper Ore (~ 1%) → Concentrate (~20 to 35%)
• milling, flotation, separation
2) Roasting and Smelting
Copper Smelting Process
CuFeS2
Cu2S (matte)
2FeOSiO2 (slag)
0.34 -1% Cu
Cu (blister)
~98% Cu
53
3) Roasting and Smelting
2FeS+3O2 2FeO+2SO2
xFeO + ySiO2 (FeO)x·(Si02)y - slag
2Cu2S + 3O2 2Cu2O + 2SO2
Cu2S + 2Cu2O 6Cu + SO2 (blister copper ~98%)
4) Electrolytic Refining (99.99%)
sulfuric acid electrolyte
anode mud (1:100) contains (Cu, Ag, As, Se, Bi, ..Au, Te…)
Copper Smelting Process
54 Source: http://encarta.msn.com/media_461547490_761561391_-1_1/Smelting_Copper.html
55
electro-refining of copper
Cu Ag Au Se Te As Sb Bi Fe Ni
20 5 0.5 5 1 5 1 3 0.25 0.05
Anode slime analysis (%) see Greadel et al (2002)
56
“The Metal Wheel”
57
Copper Summary (US)
Ayres, Ayres and Masini, 2006
58
Copper Mass Flows (US)
Ayres, Ayres and Masini, 2006
59
Copper Exergy (US)
Ayres, Ayres and Masini, 2006
60
Tailings pond at Głogow, Poland
about 7 km across
61
Estimated concentration of tailings
~ 0.2%, these tailings will be mined in the future
62
Gold Production
Placer Gold
Metal Slimes from Cu Production Open Pit Nevada
63
Open Pit Mining
Open Pit Mine in Nevada
Ore grades (ppm) Vs Time
Ref Gavin Mudd 2007
64
Open Pit Process
• Milling (grinding)
• Froth floatation
• Sodium Cyanide leaching
• Precipitation
• Extraction (Carbon in Pulp)
4 Au + 8 NaCN + O2 + 2 H2O → 4 Na[Au(CN)2] + 4 NaOH
2 Au(CN) + Zn = 2Au + Zn(CN)4-2
65
Cerro Vanguardia Gold and Silver Mine,
Argentina
66
Energy
67
Water
68
69
70
Summary
71
Liquid Metal to sheet stock
72
Material Flow Diagrams
Allwood, Cullen & Milford ES&T, 2010
73
Energy intensity of downstream processes
74
Down stream yield losses and embodied energy
75
And CO2
76
Steel dominates
(Ashby, 2011)
77
World Steel Production 1900-2010
World Steel Association
Peter Marsh, 2012
78
79 Data taken from Ashby 2009
80
81 (DOE)
82
Trends in energy intensity
IEA
Aluminum: Hall-Heroult Process
83
Material Prices
Figures from Ashby 2009
84
Apparent Saturation in Steel Stocks
Muller 2001
85
New Materials
88
2 orders
of mag.
4 to 5 orders of mag.