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.