Transcript Slide 1

Dr Gavin M Mudd
Institute for Sustainable Water Resources (Civil Eng)
Sustainable Mining :
An Evaluation of Changing Ore
Grades and Waste Volumes
www-civil.eng.monash.edu.au
Agricola (1556) :
“… the strongest argument of the detractors is that the fields are
devastated by mining operations … Also they argue that the woods
and groves are cut down, for there is need of an endless amount of
wood for timbers, machines, and the smelting of metals. And when
the woods and groves are felled, then are exterminated the beasts
and birds, very many of which furnish a pleasant and agreeable
food for man. Further, when the ores are washed, the water which
has been used poisons the brooks and streams, and either
destroys the fish or drives them away. Therefore the inhabitants of
these regions, on account of the devastation of their fields, woods,
groves, brooks and rivers, find great difficulty in procuring the
necessaries of life … Thus it is said, it is clear to all that there is
greater detriment from mining than the value of the metals which
the mining produces.”
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From Tasmania to WA and beyond :
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Sustainable Mining ?
• Debate about the impact of mining is
old indeed : debate is healthy
• There is now renewed debate about,
termed “sustainable mining”
• But what is this concept ?
Need to look at history of mining and
mineral production
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Presentation Outline
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Mining and milling ‘101’
Data : From production to sustainability
Mining industry position
Trends in Australian mineral production
Future directions & needs
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Mining & Milling ‘101’
• Essentially, ore with the mineral of
interest is excavated from the earth,
processed, refined and ‘consumed’
• Ore grades vary widely, eg. :
Gold ~2 g/t
Iron ~60%
Copper ~2%
• Excavation may be underground or
open cut
• ‘Solution Mining’ is also used (small though)
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Mining-Milling Pictorial
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Data : From Production to Sustainability
• To assess the production performance of a
mine plus the sustainability of the mining
industry, various data needs include :
– mining data, esp. %open cut v underground
> MUST include waste rock (AMD ?)
– ore milled (recovery?) – impurities (As, Hg?)
– water & energy use & management
– extent & success of rehabilitation
– emissions (eg. greenhouse gases)
• Most of this data is already collected
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Mining Industry :
Reporting & Sustainability
• In Australia, the mining industry now has a
voluntary code for environmental matters
• Many companies now publish annual
environment reports under this code
(increasingly including social issues)
• Globally, as part of the 2002 WSSD, the
mining industry published the ‘Minerals
Mining & Sustainable Development’ (or
MMSD) reports – acknowledging many
major issues facing the industry
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Mining : Some Key Issues
• Some of the major issues facing the
future of mining include :
– Declining ore grades
– Increasing waste rock / tailings volumes
– Resources versus depletion
– Land use / conservation
– Extrapolating rehabilitation performance
• These and other issues all affect the
overall sustainability of mining
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Australian Mining Industry :
Compiling the Production History
• To assess the trends in ore grades
and waste rock, a detailed compilation
of mineral production in Australia was
undertaken, including :
– Ore milled
– Ore grade
– Production
– Waste rock
– Open cut v underground mining
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Minerals-Metals Production in Australia
Copper (kt)
2,000
Gold (t)
Lead (kt)
Manganese (kt)
Manganese
Nickel (kt)
Silver (t)
Annual Production
1,600
Zinc (kt)
1,200
800
Zinc
Silver
400
Copper
Lead
Gold
Nickel
0
1845
1860
1875
1890
1905
1920
Sustainable1950
Mining
1935
: Ore 1965
Grades & Waste
12
1980Volumes /1995
Minerals-Metals Production in Australia
Bauxite (Mt)
175
14
Alumina (Mt)
Iron Ore (Mt)
150
12
Tin (kt)
Uranium (kt U3O8)
125
10
100
8
Tin
Iron Ore
75
6
Uranium
50
4
Bauxite
25
2
Diamonds
Alumina
0
1870
0
1880
1890
1900
1910
1920
1930
1940
Sustainable
Mining :1970
Ore
1950
1960
Grades
& Waste1990
Volumes /2000
13
1980
Annual Production : Uranium, Tin
Annual Production : Bauxite, Alumina, Diamonds, Iron Ore
Diamonds (Mcarats)
360
15
300
12.5
Brown Coal
Overburden
240
10
180
7.5
120
5
60
2.5
Brown Coal
Black Coal
0
1828
0
1840
1852
1864
1876
1888
1900
1912
1924
1936
1948Mining
1960
1972 & 1984
1996 / 14
Sustainable
: Ore Grades
Waste Volumes
Brown Coal Overburden (Mm 3)
Annual Raw Coal Production (Mt)
Coal Production in Australia
Coal Production : OC v UG, cumulative
90
9
Cumulative Black & Brown Coal Production (Gt)
Proportion Derived by Open Cut Mines (%)
80
70
Black & Brown Coal
60
50
Black Coal (only)
40
30
20
7.5
6
4.5
3
1.5
10
0
1940
0
1950
1960
1970
1980
1990
2000
1825
1850
1875
1900
1925
1950
1975
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2000
Gold Mining & Milling
300
45
Ore Milled
Waste Rock
Average Grade
36
180
27
120
18
60
9
0
0
1850
1870
1890
1910
1930
1950 Mining : Ore
1970
1990
Sustainable
Grades & Waste
Volumes / 16
Gold Grade (g/t) / Waste Rock as %Au
Gold Ore Milled & Waste Rock (Mt)
Waste Rock as % kg Au
240
Copper Mining & Milling
36
Ore Milled
Waste Rock
%Open Cut
100
30
Waste Rock as % t Cu
Average Grade
80
24
60
18
40
12
20
6
0
0
1844
1864
1884
1904
1924
1944
1984 Volumes / 2004
Sustainable
Mining1964
: Ore Grades & Waste
17
Copper Grade (%Cu)
Copper Ore Milled & Waste Rock (Mt) / %Open Cut / Waste as % t Cu
120
Lead-Zinc-Silver Mining & Milling
25
1350
Ore Milled
Average Lead Grade
Average Zinc Grade
1080
%Open Cut
Average Silver Grade
15
810
10
540
5
270
0
0
1880
1900
1920
1940
1960
2000/ 18
Sustainable
Mining : Ore 1980
Grades & Waste Volumes
Silver Grade (g/t)
Lead-Zinc-Silver Ore Milled (Mt) / %Open Cut
20
Data Gaps & Future Directions :
Towards Sustainable Mining
• Some mining companies do report wideranging mining-milling data - many do not
• To be meaningful, all relevant data should
be publicly reported by mining companies
and collated on an industry basis
• The “environmental burden” of modern
mining is increasing per unit of production
• Mining’s “sustainability” – depends on
ones’ perspective : jury still out
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Acknowledgements
• Numerous state Mines’ departments,
libraries, mining companies, some
consultants and several other people have
helped with the research to date
• Mineral Policy Institute (Sydney, NSW)
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