The “Limits to Growth” and ‘Finite’ Mineral Resources:
Re-visiting the Assumptions and Drinking From That Half-Capacity Glass
G M Mudd
The “Limits to Growth” and ‘Finite’ Mineral Resources:
Re-visiting the Assumptions and Drinking From That Half-Capacity Glass
G M Mudd#
Environmental Engineering, Department of Civil Engineering,
Monash University, Clayton, Melbourne, Australia; #[email protected]
Major Theme: Limits to Growth
Abstract
The famous 1972 study “Limits to Growth” (LtG) created global controversy about its dire
assessment of the potential future of humanity in the 21st century – eg. global population
crash, rampant pollution, and running out of major non-renewable resources. Amongst some
of the most fervent critics of LtG (after economic rationalists) were the mining industry, who
argued that mineral resources are easily recyclable, new technology can increase known
resources, price drives supply-demand balances, as well as exploration continuing to find new
mineral deposits. This paper will re-visit the fundamental assumptions in the LtG study,
comparing them in detail to the mega-trends in the global mining industry over the past
century – trends such as declining ore grades, increasing tailings and mine waste rock, more
refractory ores, deeper and/or larger mines, etc. Overall, the paper points to strong evidence
for both points of view regarding non-renewable mineral resources: in one corner is the ‘glass
half-full’ (industry) crew who look back and always remain optimistic about the future; while
in an opposing corner is the ‘glass half-empty’ (LtG) crew who think about the future and
believe the past justifies pessimism. Given the massive global scale of the modern mining
industry, a detailed analysis of the assumptions regarding mineral resources in the LtG study
is long overdue. This paper therefore provides a unique and thorough assessment of the
primal factors governing the sustainability of mineral resources, pointing to significant limits
to mining sometime this century – although the glass remains at half-capacity, a pessimist
might argue that optimism is proving harder to maintain.
1
Introduction
Ever since the dawn of the Industrial Revolution in the late 18th century, human population
and resource consumption has grown substantially. By 2009, human population has now
reached some 6.8 billion people and is expected to reach some 9.1 billion by 2050 (UNDESA,
2008). At about the same time, global food consumption reached 1.1 billion tonnes (Gt) of
coarse grains, 22.6 Gt of dairy products, 273.1 million tonnes (Mt) of meat products plus a
range of other food and agricultural products (eg. oils, wines, textiles, etc), as well as 1,725
Mt of iron ore, 39.3 Mt of aluminium, 15.5 Mt of copper, 11.7 Mt of zinc, 3.9 Mt of lead, and
a range of other base, precious and specialty metals (nickel, gold, platinum, etc) (ABARE,
2009). The long-term growth in resources production over time is clear, but the crucial
question is can growth be maintained into the future to meet future population projections ?
4th International Conference on Sustainability Engineering & Science: Transitions to Sustainability
Auckland, New Zealand – Nov 30.-3 Dec. 2010
1
The “Limits to Growth” and ‘Finite’ Mineral Resources:
Re-visiting the Assumptions and Drinking From That Half-Capacity Glass
G M Mudd
This has been a recalcitrant question to address, from Malthus’ time in the early 19th century
to more recent policy issues in populous countries such as China, India or in smaller countries
in Africa or South America. There have been numerous contributions since Malthus,
including Paul R. Ehrlich’s ‘Population Bomb’ (1968), the response by Julian Simon’s ‘The
Ultimate Resource’ (1981), more recently by Jared Diamond’s ‘Collapse’ (2005) and so on.
Suffice to say, population issues remain contentious and controversial.
One of the most famous and well respected studies on population and consumption was the
1972 study “Limits to Growth” (LtG), led by Donella Meadows (see Meadows et al., 1972).
The study became a best selling book and created global controversy about its dire assessment
of the potential future of humanity in the 21st century – eg. global population crash, rampant
pollution, and running out of major non-renewable resources. The primary hypothesis of the
LtG study was that exponential growth in a finite world is unsustainable. A systems dynamics
model called ‘World3’ was developed to assess trends and links in population, consumption,
resources, pollution and the economy. The World3 model was essentially qualitative, but was
tested via different scenarios or possible futures – the standard run (or business-as-usual),
comprehensive technology or a stabilised world. Under the first two scenarios, global
population crashed by the mid 21st century due to exhaustion of non-renewable resources,
environmental pollution and related problems.
One of the most strident industries critical of the LtG study was the mining industry – arguing
that most mineral resources are easily recyclable, that new technology can increase known
resources, prices drive supply-demand balances, as well as exploration continuing to find new
mineral deposits. Thus, for the foreseeable future, there was no shortage or constraint in sight
for ‘non-renewable’ mineral resources.
It is somewhat surprising that, given the gravity of LtG’s model projections and criticisms of
the LtG study by the mining industry, there is yet to be a thorough assessment of the
assumptions behind LtG’s World3 model with respect to historical trends in mining and
mineral resources. After all, every new car (conventional, hybrid or electric), electronic
gadget, building, computer, plane, etc., requires substantial mineral resources. Given the high
growth in countries such as China, and with India expected to follow soon (and not forgetting
Africa, South America, Eurasia and South-east Asia), whether currently known mineral
resources can support similar western-style consumption patterns on a global basis is much
more than a mere mathematical exercise. In terms of transitions for sustainability, it is crucial
to understand the evidence behind economic mineral resources, thereby allowing informed
technological choices, consumption patterns and a range of trade and policy initiatives.
This paper seeks to compile such a study, compiling a range of data on key mega-trends in the
global mining industry, and comparing these to the original assumptions of the LtG study.
The ongoing availability of resources and various materials is fundamental area of
sustainability which is becoming increasingly important to address given rising consumption
and more complex technological needs. The results should provide a unique and valuable
contribution to the ongoing debate concerning resources and material consumption.
2
The World3 Model, Mineral Resources and Case Study Methodology
This section will only briefly review the hypotheses used by the World3 model for mineral
resources. Further detail is given by Meadows et al. (1972), including the 30 year LtG update
(Meadows et al., 2004).
4th International Conference on Sustainability Engineering & Science: Transitions to Sustainability
Auckland, New Zealand – Nov 30.-3 Dec. 2010
2
The “Limits to Growth” and ‘Finite’ Mineral Resources:
Re-visiting the Assumptions and Drinking From That Half-Capacity Glass
G M Mudd
The two primary hypotheses used by the World3 model for non-renewable resources include:
• Finite resources: In most scenarios, minerals, metals and fossil fuels are assumed to be 7000 times
that produced in 1900 (in the remaining scenarios, half this amount is adopted).
• Increasing extraction cost: As rich and easily extracted resources are invariably developed first,
the unit discovery and production cost gradually increases over time.
These two hypotheses will be explored by case studies of trends in major mineral and metal
resources, namely coal, iron ore, bauxite-aluminium, copper, lead, zinc, nickel and platinum
group metals (PGMs). These are chosen since they play a crucial role in energy, built
infrastructure, manufactured goods and appliances or pollution control. The primary countries
analysed will include the major mining nations of Australia, Canada and the United States,
but also global trends where possible. The key aspects to be analysed, where data are
available, include production, mining method, economic resources and ore grades. Finally,
evidence on extraction cost will be reviewed, such as energy costs and pollution intensity of
resource extraction. Overall, this leads to a comprehensive and, most importantly, quantitative
assessment of the LtG hypotheses.
All data is sourced from government periodicals and series on mining, as well as industry
sources, mining companies and academic literature. Major sources include Australia (ABARE,
2009; GA, var.; Mudd, 2009), Canada (CDBS, var.; NRC, var.), and United States (Kelly et al., 2010),
global data (USBoM, var.; USGS, var.) or for specific commodities such as coal (EIA, var.; Mohr,
2010; Mohr & Evans, 2009), iron ore (Niemiec, 2009), nickel (Mudd, 2010), platinum group metals
(Glaister & Mudd, 2010).
3
Coal
Coal has been the most widely used fuel since the dawn of the Industrial Revolution, and is a
major contributor to electricity generation in numerous countries as well as being critical in
steel production. There are varying grades or ranks of coal, depending on its geologic age, and
in general they range from lignite (high moisture, low energy content), through bituminous
(low moisture, moderate energy) to anthracite (low moisture, high energy).
Accurate historical production statistics are challenging for coal, since not all countries use
the same basis for classifying coal ranks nor do they gather and/or report relevant statistics
(eg. open cut/underground, overburden, resources). However, the available data is shown in
Figures 1-2, including production by country, open cut mining and overburden-to-coal ratios.
180
Australia
Canada
Economic Resources - Black
6
World
5
4
3
2
China
1
1800
1850
1900
1950
Economic Resources - Brown
140
Inferred Resources - Brown
Australia (only)
120
100
80
60
40
20
USA
0
1750
Inferred Resources - Black
160
Black & Brown Coal Resources (Gt)
Annual Black Coal Production (raw) (Gt/year)
7
2000
0
1960
1970
1980
1990
2000
2010
Figure 1: World coal production (left); reported Australian coal resources over time (right)
4th International Conference on Sustainability Engineering & Science: Transitions to Sustainability
Auckland, New Zealand – Nov 30.-3 Dec. 2010
3
The “Limits to Growth” and ‘Finite’ Mineral Resources:
Re-visiting the Assumptions and Drinking From That Half-Capacity Glass
100
9
Australia (only)
90
8
QLD
NSW
TAS
WA
SA
VIC
Australia by State
Overburden:Coal (Raw) Ratio (m3:t)
Proportion Derived by Open Cut Mines (%)
G M Mudd
80
70
60
Black &
Brown Coal
50
40
30
Black
Coal (only)
20
7
6
5
4
3
2
1
10
0
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
0
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
Figure 2: Australia – proportion of open cut coal (left); overburden:coal ratio over time (right)
4
Iron Ore
Similarly to coal, iron has been a fundamental contributor since the Industrial Revolution, and
is almost exclusively used for steel production. Iron is widely distributed in nature, and is a
common element in the earth’s crust. The main iron minerals which can be used to make steel
are hematite, magnetite, limonite and goethite, plus possibly pyrite and pyrrhotite to a lesser
extent. The preferred mineral for steel making is hematite, though data on iron ore production
by ore type is uncommon. There have been perhaps three main growth phases in iron ore
production – the early 20th century (including interruptions by the economic depressions of
the 1920s-30s), the western post war boom (1950s-70s), and the burgeoning modernisation of
China (2000s). Iron ore production over time is shown in Figure 3, including detailed graphs
for Australian iron ore resources, estimated iron ore grades by country and beneficiated iron
ore quality for the USA.
The sudden decline in world average iron grade is due mainly to the substantial growth in iron
ore production in China, which is very low grade (~30-34 %Fe). For the USA, the long term
rise in beneficiation has allowed a progressively lower grade in raw ore to be processed, as
opposed to the grade of beneficiated product (see Figure 3).
5
Bauxite-Aluminium
Aluminium is a very light metal used in a variety of products, especially food packaging. The
production of Al starts with bauxite mining, an alumina refinery and then an Al smelter, and
makes it one of the most energy intensive metals (due mainly to total energy consumed given
the size of the Al sector). Australia is the world’s largest bauxite miner, with major alumina
refineries and Al smelters, while Canada is only involved in Al smelting as is the USA.
Bauxite production over time is shown in Figure 4.
6
Copper
Copper is a widely used metal in a variety of applications from pipes to electrical equipment
and electronics to chemicals. Copper is also widely found throughout the world, in a range of
deposit types, though porphyry deposits are now the major source of copper, especially from
North and South America (eg. Chile, Arizona, British Columbia) (Gerst, 2008). The rise of
electricity from the late 1800s saw a sustained growth in demand for copper, with production
until the mid-20th century dominated by the USA.
4th International Conference on Sustainability Engineering & Science: Transitions to Sustainability
Auckland, New Zealand – Nov 30.-3 Dec. 2010
4
The “Limits to Growth” and ‘Finite’ Mineral Resources:
Re-visiting the Assumptions and Drinking From That Half-Capacity Glass
1.8
G M Mudd
40
Economic Resources
Inferred Resources
Canadian Production
35
30
Iron Ore Resources (Gt)
Iron Ore Production & Exports (Mt)
1.5
1.2
Global Production
0.9
0.6
25
20
15
Global Exports
10
0.3
0
1900
1920
1940
5
Australia
USA
1960
1980
0
1900
2000
70
1920
1940
1960
1980
2000
100
Iron (%Fe)
64
10
Silica (%SiO2)
52
Ore Quality
Iron Ore Grades (%Fe)
58
46
40
Australia
Moisture (%)
1
Manganese (%Mn)
Alumina
(%Al2O3)
Brazil
34
Canada
China
28
0.1
Sweden
Phosphorous (%P)
USA
22
16
1905
USA (raw ore)
USSR/Russia
World (estimated)
1920
1935
1950
1965
1980
1995
0.01
1927
2010
1937
1947
1957
1967
1977
1987
Figure 3: Iron ore production trends over time (top left); Australian economic and inferred iron ore
resources (top right); estimated ore grades for select countries (%Fe) (bottom left); beneficiated iron
ore quality in the USA (bottom right)
12
Australian Bauxite Grade (%Al2O3)
10
176
Australian Bauxite Resources (Gt)
Annual Production (Mt) / Bauxite Grade (%Al2O3)
220
Global
Bauxite
(Mt)
132
88
Australian
Bauxite
(Mt)
44
0
1925
Total Bauxite Resources (Gt)
8
6
4
2
Aust. Alumina (Mt)
1935
1945
1955
1965
1975
1985
1995
2005
0
1950
Economic Bauxite Resources (Gt)
1960
1970
1980
1990
2000
2010
Figure 4: Global and Australian bauxite-alumina production trends over time (left); Australian
economic and inferred (total) bauxite resources (right)
4th International Conference on Sustainability Engineering & Science: Transitions to Sustainability
Auckland, New Zealand – Nov 30.-3 Dec. 2010
5
The “Limits to Growth” and ‘Finite’ Mineral Resources:
Re-visiting the Assumptions and Drinking From That Half-Capacity Glass
G M Mudd
Overall, global production mirrors major events such as the 1920s and 1930s economic
depressions, followed by major industrialisation after World War 2. By the 1990s, Chile had
emerged as the world’s biggest Cu producer, from large to super-giant porphyry mines along
the high altitude Andean Cordillera. Historical and recent Cu production is shown in Figure 5,
long term ore grade trends in Figure 6, and economic Cu resources and Cu prices shown in
Figure 7. Most Cu is produced from open cut mining.
16
16
14
12
10
8
Annual Copper Production (Mt Cu)
Annual Copper Production (Mt Cu)
14
12
Other Countries (rest of world)
10
8
6
Chile
World
4
2
Canada
Australia
United States
6
0
1990
1992
1994
1996
1998
Chile
2000
2002
2004
2006
2008
4
2
World
USA
Australia
Canada
USA
Chile
0
1840
1860
1880
1900
1920
1940
1960
1980
2000
Figure 5: Global Cu production over time
7
24
21
Copper Ore Grade (%Cu)
Copper Ore Grade (%Cu)
6
27
USA
Canada
World
Australia
5
4
18
15
12
9
6
3
3
0
1840
1860
1880
1900
1920
1940
1960
1980
2000
2
1
0
1900
1920
1940
1960
1980
2000
Figure 6: Trends in Cu ore grades for Australia, Canada and the USA
Although Australia shows increasing resources over time, the USA and Canada appear to be
in very gradual but terminal decline. However, a critical trend for all countries is the long
term decline in ore grades, as well as the evolving nature of ore types from oxide ores of the
mid-1800s to the large low grade porphyry sulfides now dominant in the Cu industry globally.
4th International Conference on Sustainability Engineering & Science: Transitions to Sustainability
Auckland, New Zealand – Nov 30.-3 Dec. 2010
6
The “Limits to Growth” and ‘Finite’ Mineral Resources:
Re-visiting the Assumptions and Drinking From That Half-Capacity Glass
G M Mudd
96
96
Australia
Canada
84
USA - Reserves
USA - Reserves Base
7,700
1.4
6,600
1.2
5,500
1.0
4,400
0.8
60
48
36
24
3,300
0.6
Real price
2,200
0.4
1,100
72
Indexed Real Price in 1998$ (1900 = 1)
72
Nominal Price (US$/t Cu)
Economic Copper Resources (Mt Cu)
84
60
48
36
24
0.2
Nominal price
12
0
1900
1910
0
1890
1920
1910
1930
1940
1950
1930
1960
1970
1980
1950
1990
2000
0.0
2010
1970
12
1990
0
2010
Figure 7: Economic Cu resources over time for Australia, Canada and the USA (main), with nominal
and real (US$1998) Cu prices over time (inset)
7
Lead and Zinc
Lead ores had been mined on a small to moderate scale in Europe for many centuries, but it
was not until the large discoveries in the USA, Canada and Australia in the late 1800s and
early 1900s that global lead production began to grow rapidly. This occurred at the same time
as the rapid deployment of lead-based munitions, as well as a range of other uses (eg. petrol
additive). At sites such as Broken Hill in Australia, the new technology of ore flotation was
invented by 1905 to allow efficient separation of lead and zinc sulfides – one of the most
pivotal technologies of mining throughout the 1900s and remains so today. Lead, however, is
a toxic heavy metal and since the 1970s has been under significant pressure to reduce lead
emissions to the environment from uses such as a petrol additive.
Zinc is a widely used metal, especially in galvanising steel or other metal alloys such as brass
and die casts. Zinc often occurs in conjunction with lead and silver, and they are all mined
and extracted together. Zinc can also be found in association with Cu, such as the large low
grade Antamina Cu-Zn mine in Peru.
In the past decade, somewhat surprisingly, China has emerged as the world’s largest producer
of lead and zinc, though virtually no mine-specific data is available. Australia, Canada, India
and the USA remain large global producers, dominantly from large high grade mines such as
Century, Brunswick, Rampura Agucha and Red Dog, respectively. Production trends, ore
grades and economic resources over time for lead and zinc are shown in Figure 8.
8
Nickel
Until the late 1800s, nickel had only minor uses and was only mined on a small scale in
Europe and was just beginning in French-controlled New Caledonia in the Pacific. By the
1880s, the role of Ni in stainless steel and armour plating was established and this caused a
growing demand for Ni, especially for navies keen to modernise. Also in the 1880s, the
Sudbury field of northern Ontario, Canada was discovered, proving to be a rich and supergiant resource of Ni as well as Cu and a small producer of cobalt and platinum group metals.
4th International Conference on Sustainability Engineering & Science: Transitions to Sustainability
Auckland, New Zealand – Nov 30.-3 Dec. 2010
7
The “Limits to Growth” and ‘Finite’ Mineral Resources:
Re-visiting the Assumptions and Drinking From That Half-Capacity Glass
G M Mudd
4
12
3.5
USA
Canada
China
World
Australia
Peru
USA
Canada
China
10
Annual Lead Production (Mt Pb)
World
3
8
2.5
World
2
6
1.5
China
4
China
1
Annual Zinc Production (Mt Zn)
World
Australia
Peru
2
USA
0.5
Canada
Australia
0
1840
1860
1880
1900
1920
1940
Australia
Canada
1960
1980
0
2000
1840
1860
1880
1900
1920
1940
1960
1980
2000
18
32
80
28
Lead Ore Grade (%Pb)
24
20
70
16
60
14
50
Australia Northampton, WA field only
(hand-sorted ore)
40
20
1855
16
12
30
10
Australia
1860
1865
1870
1875
1880
1885
8
Australia
12
6
8
Zinc Ore Grade (%Zn)
Lead Ore Grade (%Pb)
Expected true grade range
4
Canada
4
2
Canada
1900
1920
1940
1960
1980
2000
1890
1910
1930
1950
1970
0
2010
1990
32
12
USA - Reserves Base
USA - Reserves Base
2,800
1.4
2,400
1.2
2,000
1.0
1,600
0.8
1,200
0.6
Real price
800
0.4
400
84
3,600
3.0
3,000
2.5
2,400
2.0
1,800
1.5
1,200
1.0
Real price
600
0.2
0.5
72
Indexed Real Price in 1998$ (1900 = 1)
16
USA - Reserves
Canada
USA - Reserves
Nominal Price (US$/t Zn)
20
Australia
Canada
Indexed Real Price in 1998$ (1900 = 1)
24
Nominal Price (US$/t Pb)
Economic Lead Resources (Mt Pb)
28
96
Australia
60
48
36
Nominal price
0
1900
Nominal price
0.0
1920
1940
1960
1980
0
1900
2000
0.0
1920
1940
1960
1980
2000
8
24
4
12
0
1900
Economic Zinc Resources (Mt Zn)
0
1880
0
1920
1940
1960
1980
2000
1900
1920
1940
1960
1980
2000
Figure 8: Lead and zinc production over time (top); Ore grades over time (middle); Economic
resources over time (bottom), with nominal and real (US$1998) Pb-Zn prices over time (inset)
Until about 1950, Canada was the dominant Ni supplier of the western world. After 1950,
other countries emerged as major Ni producers, such as Russia (especially the NorilskTalnakh field of Siberia), Australia (eg. Kambalda), Indonesia, China and others.
4th International Conference on Sustainability Engineering & Science: Transitions to Sustainability
Auckland, New Zealand – Nov 30.-3 Dec. 2010
8
The “Limits to Growth” and ‘Finite’ Mineral Resources:
Re-visiting the Assumptions and Drinking From That Half-Capacity Glass
G M Mudd
Nickel is found in two main ore types – sulfides and laterites. The Sudbury field is sulfides,
while the Russia and Australia fields are mostly sulfides with some moderate laterite mines.
In contrast, many tropical countries possess substantial laterite Ni resources and mines, such
as Indonesia, Cuba, the Philippines, Columbia and New Caledonia. In general, sulfides are
relatively easily processed through conventional pyrometallurgy (eg. mine, mill, smelter,
refinery), while laterites require more complex processing (such as rotary kiln electric
furnaces or high pressure acid leach and hydrometallurgical plants). Production trends, ore
grades and economic resources over time for lead and zinc are shown in Figure 9, with the
relationship between unit energy and greenhouse intensity for Ni production in Figure 10.
1,750
Ore Type by Fraction
1
1,250
1,000
Laterite
0.8
Laterite
0.6
0.4
Sulfide
0.2
Laterite
2005
1995
1985
1975
1965
1955
1945
1935
1925
1915
1905
1895
0
750
1885
Annual Nickel Production (kt Ni/year)
1,500
500
Russia
(sulfide)
Miscellaneous Sulfide
250
Australia (sulfide)
Canada
(sulfide)
2005
1995
1985
1975
1965
1955
1945
1935
1925
1915
1905
1895
1885
0
12
28
Australia (economic)
Canada
Australia (sub-economic)
20
8
16
6
12
4
8
Canada
2
0
1870
Economic Nickel Resources (Mt Ni)
24
New Caledonia
10
Nickel Ore Grade (%Ni)
Australia
4
1890
1910
1930
1950
1970
1990
2010
1965
1970
1975
1980
1985
1990
1995
2000
2005
0
2010
Figure 9: Nickel production by country and ore type (top); Nickel ore grades over time (bottom left);
Economic and sub-economic (inferred) nickel resources (bottom right)
As shown in Figure 10, in general, Ni laterite is more intensive to produce than sulfides, but
this can be site-specific. For example, the Yabulu project uses the older Caron ammonia lead
process while Murrin Murrin uses high pressure acid leach – meaning Yabulu remains more
energy-CO2 intensive. Curiously, for the same unit energy intensity for the Thompson and
Sudbury fields of Canada, the CO2 footprint is substantially different – highlighting the
critical importance of energy sources and configuration.
4th International Conference on Sustainability Engineering & Science: Transitions to Sustainability
Auckland, New Zealand – Nov 30.-3 Dec. 2010
9
The “Limits to Growth” and ‘Finite’ Mineral Resources:
Re-visiting the Assumptions and Drinking From That Half-Capacity Glass
G M Mudd
50
Sulfide Projects
Laterite Projects
t CO2/t metal
40
30
Inco Sudbury
Thompson
20
Murrin Murrin
Sorowako
WMC Total
10
Yabulu
Xstrata Canada
Cerro Matoso
0
0
100
200
300
400
500
600
700
GJ/t metal
Figure 10: Unit energy and greenhouse intensity for Ni(±Cu±Co) production (Mudd, 2010)
9
Platinum Group Metals
The platinum group of metals (namely platinum, iridium, osmium, palladium, rhodium, and
ruthenium; or PGMs) are increasingly important in a range of environmentally related
technologies and uses, such as catalytic converters to control vehicle exhaust emissions,
chemical catalysts in process plants (especially oil refineries), electronic components, and
hydrogen fuel cells. Many of these applications have only grown in demand since the 1960s.
South Africa dominates world PGMs production (mainly platinum), followed by Russia
(mainly palladium), with minor production from Canada and the USA. The South African
industry is unique in that it contains some 90% of the world’s PGMs resources, all in the
Bushveld Igneous Complex in North West Province (just north of Johannesburg and Pretoria).
Historical production by country is shown in Figure 11, with unit greenhouse gas emissions
versus ore grade (left) and over time for some South African mines shown in Figure 12.
United
States
35,000
500
US$/kg PGM
1998 US$/kg PGM
30,000
Annual PGM Production (t)
300
Price (US$/kg PGM)
25,000
400
20,000
15,000
10,000
5,000
200
0
1900
1920
1940
1960
1980
2000
Russia
100
South Africa
Canada
0
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
Figure 11: Platinum group metal production by country (main); and nominal and real prices
(US$1998) over time (inset) (Glaister & Mudd, 2010)
4th International Conference on Sustainability Engineering & Science: Transitions to Sustainability
Auckland, New Zealand – Nov 30.-3 Dec. 2010
10
The “Limits to Growth” and ‘Finite’ Mineral Resources:
Re-visiting the Assumptions and Drinking From That Half-Capacity Glass
80
80
Mine & Concentrator
Mine, Concentrator & Smelter
70
Unit GHG Emissions (t CO2/kg PGM)
Unit GHG Emissions (t CO2-e/kg 4E PGMs)
G M Mudd
60
50
40
30
y = 140.97x-1.0182
2
R = 0.3807
20
10
Bafokeng-Rasimone
Lebowa
Potgietersrust
Amandelbult
70
Rustenberg
Union
60
Marula
Implats
Zimplats
Lonmin
50
40
30
20
10
0
3
3.5
4
4.5
5
Ore Grade (4E g/t)
5.5
6
6.5
0
2001
2002
2003
2004
2005
2006
2007
2008
2009
Figure 12: Unit greenhouse gas (GHG) emissions versus ore grade (left) and over time (right) for
platinum group metals production (Glaister & Mudd, 2010)
10
Discussion
The extensive data sets in this paper provide a unique insight into the hypotheses used for
non-renewable mineral resources.
The extent of ‘finite resources’ is variable depending on commodity and country. For
example, Australia’s Ni resources have increased substantially over the past 50 years
(especially if sub-economic resources are included) whilst Canada’s have declined steadily.
Based on reported resources at operating mines and undeveloped deposits, Canada’s known
Ni resources are clearly more than report. This apparent discrepancy is simply due to the
stringent standard set by Canada – only Ni remaining at operating mines and in economic
reserves are included in national estimates, and not additional resources. This seemingly
contradictory picture is also true for lead, zinc and copper and possibly for coal also.
Although the data is not available, based on the history of the PGMs sector in South Africa, it
can be expected that there are substantial PGMs resources remaining (Glaister & Mudd,
2010). Part of these patterns can be explained by new technology, either allowing more
intensive and productive exploration (especially geophysics) or mining and processing of
previously uneconomic or difficult ores (eg. carbon in pulp for gold, high pressure acid
leaching of Ni laterites).
The obvious question is whether these ‘patterns of the past’ can be continued into the future –
an optimist would look to history and feel comfortable that we are far from approaching limits
to extractable mineral resources; whilst a pessimist would consider future demands for
business-as-usual (eg. exponential growth in metals demand), and conclude that no scenario
of new discoveries or more technology can meet demand, especially considering the pollution
costs of minerals and metals production. The evident issue is therefore the patterns of this
century which will govern mineral resources and their utilisation – not merely the extent of
‘recoverable’ or finite resources.
This raises the second hypothesis – the increasing cost of mineral resource extraction. This
can be considered in numerous ways – either through increasing unit energy costs (eg. GJ/t
Cu) as ore grades decline, the increasing waste rock from open cut mining and tailings, water
resources impacts, greenhouse gas constraints (eg. emissions trading), and so on. Given that
ore grades are in effectively terminal decline for all minerals and metals analysed, this means
4th International Conference on Sustainability Engineering & Science: Transitions to Sustainability
Auckland, New Zealand – Nov 30.-3 Dec. 2010
11
The “Limits to Growth” and ‘Finite’ Mineral Resources:
Re-visiting the Assumptions and Drinking From That Half-Capacity Glass
G M Mudd
that unit energy costs will continue to increase in the absence of new technology or
substantial energy efficiency efforts. In the face of climate change risks, this is a substantial
challenge for the global mining industry. For example, if one extrapolates increased
production and declining ore grades to say 2050 in conjunction with reductions in greenhouse
gas emissions of 50% from 2000 levels by this time, it is clear that a considerably greater
reduction in unit greenhouse intensity is required per tonne of mineral than just 50%.
Furthermore, in some regions of the world, especially coal regions such as the Appalachians
in the USA or the Hunter Valley of Australia, cumulative environmental and social impacts
are already significant, and leading to growing community concern. The availability of water
and/or impacts on water resources are also becoming more critical to the future of the mining
industry globally (Mudd, 2008).
As such, although the World3 model argued for increasing environmental costs of resource
extraction from a largely conceptual standpoint, it is clear that this hypothesis is being
observed in reality. For example, the recent energy intensity of the Australia mining industry,
in kWh/$ value, was shown to have increased by some 50% over the past decade (Sandu &
Syed, 2008). Thus the hypothesis is eminently reasonable, regardless of whether one is an
optimist or pessimist.
11
Conclusions
This paper compiled a range of data on key mega-trends in the global mining industry, and
comparing these to the original assumptions of the “Limits to Growth” study. The ongoing
availability of resources and various materials is a fundamental area of sustainability which is
becoming increasingly important to address given rising consumption and more complex
technological needs. The LtG study, namely the World3 model, used two principal
hypotheses for non-renewable resources – finite resources and increasing extraction cost.
Although there is clear evidence of increasing extraction costs over time, especially as ore
grades are in terminal decline, the evidence for finite resourecs is more complex and varies
across commodities and countries. In this regard, it is possible for the LtG study to be both
right and wrong at the same time – optimists look to history and say we have yet to run out,
while pessimists extrapolate diligently into the future and argue that such historical patterns
are clearly not sustainable. In effect, the glass remains at half-capacity, although a pessimist
might argue that optimism is proving harder to maintain.
12
Acknowledgements
This paper is part of continuing work on the sustainability of mineral resources. Specific
thanks to Steve Mohr for coal data. The CSIRO Mineral Futures Collaboration Cluster is also
acknowledged for funding of peak minerals research work. The Mineral Policy Institite also
deserves recognition for their in-kind support of this research.
13
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Auckland, New Zealand – Nov 30.-3 Dec. 2010
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Re-visiting the Assumptions and Drinking From That Half-Capacity Glass
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Auckland, New Zealand – Nov 30.-3 Dec. 2010
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