eng.monash.edu.au/enveng

Dr Gavin M MuddDr Gavin M MuddEnvironmental EngineeringEnvironmental Engineering

Sustainability Metrics Sustainability Metrics of Gold Miningof Gold Mining

February 2007February 2007

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 2Institute for Sustainable Water Resources

Gold …Gold …

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 3Institute for Sustainable Water Resources

Gold Mining v Sustainability ?Gold Mining v Sustainability ?

• Define oxymoron : sustainable gold miningDefine oxymoron : sustainable gold mining• Gold mining has been a critical aspect of Gold mining has been a critical aspect of

economic and social development in many economic and social development in many countriescountries

• Gold mining has also left a legacy of Gold mining has also left a legacy of impacts – social, environmental, etcimpacts – social, environmental, etc

• The application of sustainability principles The application of sustainability principles to gold mining is, at first, counter-intuitiveto gold mining is, at first, counter-intuitive

• This paper attempts to compile such data !This paper attempts to compile such data !

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 4Institute for Sustainable Water Resources

Gold Mining & Sustainability MetricsGold Mining & Sustainability Metrics

• Data Sources and MethodologyData Sources and Methodology• Analysis of Sustainability MetricsAnalysis of Sustainability Metrics• Results – Global Gold ProductionResults – Global Gold Production• Results – Energy, Water and Cyanide Results – Energy, Water and Cyanide

ConsumptionConsumption• Results – Greenhouse EmissionsResults – Greenhouse Emissions• Discussion : Deficiencies, Future Work …Discussion : Deficiencies, Future Work …• SummarySummary

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 5Institute for Sustainable Water Resources

Analysis of Sustainability MetricsAnalysis of Sustainability Metrics

• Some key issues for sustainability include Some key issues for sustainability include energy, water and cyanide consumption energy, water and cyanide consumption and greenhouse emissionsand greenhouse emissions

• The ‘eco-efficiency’ of various gold mines The ‘eco-efficiency’ of various gold mines is compared using the unit consumption is compared using the unit consumption (/emission) per gold produced relative to (/emission) per gold produced relative to ore grade and ore throughput :ore grade and ore throughput :– kL water / kg Au; t COkL water / kg Au; t CO22 / kg Au; GJ energy / kg Au / kg Au; GJ energy / kg Au

– kL water / t ore; t COkL water / t ore; t CO22 / t ore; GJ energy / t ore / t ore; GJ energy / t ore

– t cyanide / kg Aut cyanide / kg Au

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 6Institute for Sustainable Water Resources

Global Historical Gold ProductionGlobal Historical Gold Production

0

250

500

750

1,000

1,250

1,500

1,750

2,000

2,250

2,500

2,75018

40

1850

1860

1870

1880

1890

1900

1910

1920

1930

1940

1950

1960

1970

1980

1990

2000

Go

ld P

rod

uc

tio

n (

t A

u)

Rest of the World

United States

South Africa

Canada

Australia

United States - California

Australia - Eastern States

South Africa(Witwatersrand)

Australia -Western Australia

Gold price rise,Carbon-in-pulp developed

major world expansion of gold mining

AustraliaCanada

USA

South Africa

Rest ofthe World

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 7Institute for Sustainable Water Resources

Global Historical Gold Ore GradesGlobal Historical Gold Ore Grades

0

5

10

15

20

25

30

35

40

1830 1845 1860 1875 1890 1905 1920 1935 1950 1965 1980 1995

Go

ld G

rad

e (

g/t

Au

)

Brazil

USA

South Africa

Australia

Canada

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 8Institute for Sustainable Water Resources

Unit Water Consumption v GradeUnit Water Consumption v Grade

0

1,500

3,000

4,500

6,000

7,500

0 10 20 30 40 50

Gold Grade (g/t Au)

Wa

ter

Co

ns

um

pti

on

pe

r G

old

Pro

du

ced

(k

L/k

g A

u)

Africa

Asia-Pacific

Australia

Canada

Central & South America

United States

Canada - (82.4, 51.6)

Asia-Pacific (4.27, 8,342; 5.11, 9,442)

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 9Institute for Sustainable Water Resources

Unit Water Consumption v OreUnit Water Consumption v Ore

0

1

2

3

4

5

6

7

8

9

0 5 10 15 20 25 30 35 40 45

Ore Milled (Mt/yr)

Wa

ter

Co

ns

um

pti

on

pe

r t

Ore

Mil

led

(k

L/t

ore

)

Africa

Asia-Pacific

Australia

Canada

Central & South America

United States

Asia-Pacific (1.97, 28.0; 2.35, 48.0; 2.91, 38.9; 3.41, 32.6; 4.09, 43.0)Africa - (12.87, 21.33)

United States - (59.6, 0.088)& (63.2, 0.102)

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 10Institute for Sustainable Water Resources

Unit Energy Consumption v GradeUnit Energy Consumption v Grade

0

100

200

300

400

500

600

700

0 10 20 30 40 50

Gold Grade (g/t Au)

En

erg

y C

on

su

mp

tio

n p

er

Go

ld P

rod

uc

ed (

GJ

/kg

Au

)

Africa

Asia-Pacific

Australia

Canada

Central & South America

United States

Central & South America - (0.64, 1,076)

Canada - (82.4, 21.9)& (77.1, 22.9)

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 11Institute for Sustainable Water Resources

Unit Energy Consumption v OreUnit Energy Consumption v Ore

0

0.5

1

1.5

2

2.5

3

0 5 10 15 20 25 30 35 40 45

Ore Milled (Mt/yr)

En

erg

y C

on

su

mp

tio

n p

er

t O

re M

ille

d (

GJ

/t o

re)

Africa

Asia-Pacific

Australia

Canada

Central & South America

United States

Africa - (0.98, 3.87)

United States - (59.6, 0.042)& (63.2, 0.038)

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 12Institute for Sustainable Water Resources

Unit Cyanide Consumption v GradeUnit Cyanide Consumption v Grade

0

100

200

300

400

500

600

700

800

900

1,000

1,100

0 2 4 6 8 10 12 14 16 18

Gold Grade (g/t Au)

Cy

an

ide

Co

ns

um

pti

on

pe

r G

old

Pro

du

ce

d (

kg

CN

/kg

Au

)

Africa

Asia-Pacific

Australia

Canada

Central & South America

United States

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 13Institute for Sustainable Water Resources

Unit Greenhouse Emissions v GradeUnit Greenhouse Emissions v Grade

0

10

20

30

40

50

0 10 20 30 40 50

Gold Grade (g/t Au)

CO

2 E

mis

sio

ns

pe

r G

old

Pro

du

ce

d (

t C

O2/k

g A

u)

Africa

Asia-Pacific

Australia

Canada

Central & South America

United States

Central & South America - (0.64, 76.7)

Canada - (82.4, 0.2)& (77.1, 0.2)

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 14Institute for Sustainable Water Resources

Unit Greenhouse Emissions v OreUnit Greenhouse Emissions v Ore

0

50

100

150

200

250

0 10 20 30 40 50 60 70

Ore Milled (Mt/yr)

CO

2 E

mis

sio

ns

pe

r t

Ore

Mil

led

(k

g C

O2/

t o

re)

Africa

Asia-Pacific

Australia

Canada

Central & South America

United States

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 15Institute for Sustainable Water Resources

Discussions & Debates ..Discussions & Debates ..

• Gold mining has occurred throughout the Gold mining has occurred throughout the world, with main factors including :world, with main factors including :– new discoveries, prices, technology, social, …new discoveries, prices, technology, social, …

• The most recent gold boom (>1980) has The most recent gold boom (>1980) has seen unprecedented global gold miningseen unprecedented global gold mining

• Fundamental trends for gold mining :Fundamental trends for gold mining :– declining ore grades, open cuts, technology, …declining ore grades, open cuts, technology, …

• Sustainability metrics, unit consumption/ Sustainability metrics, unit consumption/ emissions, are highly grade dependentemissions, are highly grade dependent

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 16Institute for Sustainable Water Resources

Sustainability ‘Costs’ of GoldSustainability ‘Costs’ of Gold

• In general, based on data within this paper, In general, based on data within this paper, the production of gold entails :the production of gold entails :

per t Oreper t Ore per kg Auper kg Au

WaterWater 1.69 kL / t ore1.69 kL / t ore 773 kL / kg Au773 kL / kg Au

EnergyEnergy 0.34 GJ / t ore0.34 GJ / t ore 149 GJ / kg Au149 GJ / kg Au

CyanideCyanide -- 147 kg / kg Au147 kg / kg Au

Carbon Carbon DioxideDioxide

23.4 kg CO23.4 kg CO22 / t / t

oreore11.6 t CO11.6 t CO22 / t ore / t ore

2nd Int Conf on Sustainability Eng/Sci : Sustainability Metrics of Gold Mining / 17Institute for Sustainable Water Resources

Summary & ConclusionsSummary & Conclusions

• Gold Mining continues around the worldGold Mining continues around the world

• Gold ore grades are in terminal declineGold ore grades are in terminal decline

• Sustainability metrics are clearly linked and Sustainability metrics are clearly linked and very sensitivevery sensitive to ore grade to ore grade

• Due to the low grade, gold production Due to the low grade, gold production entails significant unit costs for water, entails significant unit costs for water, energy, cyanide, greenhouse emissionsenergy, cyanide, greenhouse emissions

• Future sustainability is difficult to predict …Future sustainability is difficult to predict …