jillian aira s. gabo, d.eng. department of earth resources ... · mineral deposits. •mineral...

Mineral ResourcesMineral Resources Jillian Aira S. Gabo, D.Eng.

Department of Earth Resources Engineering

Kyushu University

OutlineOutline • Economic geology

• Mineral resources

• Economics of mining

• History of mining

• Environmental Effects of Mining

• Mining Issues

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Economic GeologyEconomic Geology • Economic geology is a subdiscipline of the geosciences

• It devotes itself to:

- the scientific study of Earth’s sources of mineral raw materials

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Economic GeologyEconomic Geology

• Practical mission: provision of metals & minerals that society requires

• Mining – extraction of valuable minerals or other geologic materials from the earth

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• Major roles in the life-cycle of a mine:

- leads in the search for new mineral deposits

- contributes to economic & technical evaluations

- continuously updates mineable reserves

- limits impact to the environment

- aids in rehabilitation after mine closure

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Economic GeologyEconomic Geology

• Everyone consumes minerals and mineral-derived products in daily life

• Rapid population growth and demands for a better life enforce expansion of mineral resource production

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Mineral ResourcesMineral Resources

http://eps.berkeley.edu/courses/eps50/documents/lecture31.mineralresources.pdf

Mineral ResourcesMineral Resources

Virtually everything we use or build or create in modern life involves mineral and fuel resources taken from the Earth

If it can’t be grown, it has to be mined…

Mineral ResourcesMineral Resources • Mineral resources are natural resources in the form of

mineral deposits.

• Mineral deposits are any volume of rock containing an enrichment of one or more minerals.

• Mineral resources have 3 distinctive characteristics: o Occurrences of usable minerals are limited in abundance and

localized at places within the crust.

o The quantity of a given mineral available in any one country is rarely known with accuracy.

o Deposits of minerals are depleted by mining and eventually exhausted.

Mineral ResourcesMineral Resources • Ore is a natural material from which valuable or useful

metal occurs at a sufficient concentration, relative to average rocks, to make it economically worth mining

• Ore minerals rarely occur alone. They occur with other non-valuable minerals, collectively termed gangue

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concentrate Remove

Mineral ResourcesMineral Resources

Ore depositsOre deposits

• Composition of the Earth’s crust

Ore depositsOre deposits

The remaining 1.5% contains a staggering number of rocks and minerals that are useful to modern society, but only occur in very limited quantities in nature

In fact, many resources are extremely rare...

Ore depositsOre deposits

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10-5

10-3

10-1

101

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10-4

10-3

10-2

10-1

100

101

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AluminumIron

CopperNickel

Zinc

Uranium

Lead

Silver

Gold

y = x

Typic

al O

rebody C

once

ntr

atio

n

Crustal Concentration

Ore depositsOre deposits

S Africa 50% Gold; 75% Chromium; 90% Platinum

USA 50% Molybdenum;15% Lead

Chile 30% Copper

Cuba 40% Nickel

Guinea & Australia 25% each of Aluminum

Zaire 50% cobalt

Ore depositsOre deposits

Plate Tectonics and Plate Tectonics and Ore depositsOre deposits

Rock CycleRock Cycle Classification

of rocks:

Igneous

Sedimentary

Metamorphic

Igneous RocksIgneous Rocks

Formed from solidification of magma

(intrusive) or lava which flows out from depths

(extrusive)

Intrusive (plutonic):

formed at depth

Extrusive (volcanic):

solidified at the surface

Igneous Igneous Rocks: ClassificationRocks: Classification

Felsic Intermediate Mafic Ultramafic

Po

rph

yrt

ic

Fin

e

Co

arse

Igneous Rocks: ResourcesIgneous Rocks: Resources Dimension stone – for building ornamentation

(granite, basalt, etc) (avoid fractured rocks)

Aggregates – for construction (e.g. basalt for

paving asphalt)

Foundations – sites for construction

Sedimentary RocksSedimentary Rocks Lithified sediments held together by various

types of cementing agents, or by compaction of

mineral grains into a hardened mass

Sediments – loose debris: Gravels, sands, silts, clay

• Formed by these processes: - Weathering: fractures and dissolves rock - Erosion: carries away the products of weathering - Deposition & burial: accumulate & compact

• Two types: Clastic/detrital & Non-clastic/non-

detrital

Sedimentary Sedimentary Rocks: Rocks: ClassificatioClassificationn

Clastic/Detrital - consists of discrete fragments

& particles cemented & compacted together

- clast,

matrix,

cement

Sedimentary Sedimentary RocksRocks: : ClassificationClassification

Non-clastic/Non-detrital - minerals form a pattern

of interlocking crystals

- Formed by biochemical and chemical processes

Sedimentary RocksSedimentary Rocks: : ResourcesResources

Construction materials – cement (limestone,

clay/shale); bricks (clay); glass (silica sand)

Aggregates – for road pavement (e.g. fine-

grained limestone and dolomite); concrete (sand

& gravel)

Metamorphic RocksMetamorphic Rocks • Metamorphism - change undergone by an

existing rock, in the solid state, to another rock

Metamorphic Rocks: Metamorphic Rocks: ClassificationClassification

• Foliated

Metamorphic Metamorphic Rocks: Rocks: ClassificationClassification

Non-foliated

Metamorphic RocksMetamorphic Rocks: : ResourcesResources

Dimension stone – for building ornamentation,

roofing, flooring (marble, slate, phyllite, schist)

• 6 metals utilized since antiquity:

> Gold, copper, meteoric iron - occur in native state

(scattered finds of megascopic surface particles )

> Tin, silver, lead - required primitive smelting

* smelting of tin & copper – bronze (Bronze Age)

http://www.featurepics.com/FI/Thumb300/20080219/Gold-Pan-Gold-Nuggets-619486.jpg http://www.antiquaprintgallery.com/ekmps/shops/richben90/imag

es/manufacturing-primitive-furnace-for-smelting-iron-1893-50634-p.jpg

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History of MiningHistory of Mining

• Smelting of iron came later (~1300 BC)

• The first people to use oil instead of wood for fuel were the Babylonians (~2500 BC)

• The first people to mine and use coal were the Chinese (~1000 BC)

http://members.tripod.com/east_west_dialogue/sitebuildercontent/sitebuilderpictures/blastfurnaceup.jpg

http://www.nature.com/polopoly_fs/7.2784.1328816300!/image/1.10011_blacksmiths.jpg_gen/derivatives/landscape_630/1.10011_blacksmiths.jpg

History of MiningHistory of Mining

• Early mining developed by following ore outcrops to depth (before 3,000 BC)

• Mines increased when metallic deposits were discovered in conquered areas during empire building

• Earliest recorded metal mining & recovery:

Sumerians mining and processing copper (~3500 BC)

http://www.mitchellteachers.net/WorldHistory/MrMEarlyHumansProject/MrMSumerianCivilizationAchievements.html 32

History of MiningHistory of Mining

• Earliest recorded mines:

> Sar Chesmeh oxidation zone, Iran - Cu

> Wadi Arabah, Israel – Cu

> Iberian Pyrite Belt (Tharsis & Rio Tinto) – Cu, Au

> Egypt: Cu in Sinai & Hijaz; Au in E. Desert & Nubia

http://www.marketoracle.co.uk/Article1398.html

http://www.atlasobscura.com/uploads/assets/01-Tinto.jpg

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History of MiningHistory of Mining

• Pre-Middle Ages (5th Century)

> Antimony, arsenic, mercury - utilized as compounds (pigments & poisons)

• Middle Ages

> Zinc – alloy with copper to form brass

> Manganese, chromium, nickel – alloyed

with iron for medieval weapons

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History of MiningHistory of Mining

• Industrial Revolution (1750s)

> onset of modern chemistry

> isolation and discovery of new metals & elements

> Mendeleev - 49 new metals to Periodic Table (1751~ )

• Discovery of practical application of metals driven by Industrial Revolution, major wars, breakthroughs in electronics & biotechnology

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History of MiningHistory of Mining

Laznicka, 2012

History of MiningHistory of Mining

Laznicka, 2012

History of MiningHistory of Mining

• Industrial metals are mineral commodities;

articles of trade or commerce

• Commodity prices (metal prices):

- based on supply and demand at a particular time

- mostly determined at London Metals Exchange;

change on a daily basis

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Economics of MiningEconomics of Mining

• Metal prices influence profitability of metal deposits

> High metal prices – possible to mine low-grade ore

> Low metal prices – mines resort to high-grading; cause deferment of mine projects

• Correlation between metal price and scarcity:

> rare metals (e.g. Au) more expensive than common metals (e.g. Al, Cu & Fe)

• Price also dictated by cost of production

e.g. metallic Ti - abundant, but high production cost

Sb, Hg – scarce, but cheap to mine & process

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Economics of MiningEconomics of Mining

• Gold is found in very small amounts in the crust, typically 4 ppb (parts per billion)

• At 4,281円 per gram (as of 15 July 2014), gold is economical to mine even at ppm concentrations

1 g Au

Economics of MiningEconomics of Mining

• Copper has an average concentration of 100 ppm in the crust (25,000 times more common than Au)

• Since copper is only worth a fraction of the value of gold (328円 per pound = 0.73円 per gram), it must be 100,000 times higher in concentration than gold to be economical to mine

Economics of MiningEconomics of Mining

Copper – As An Example

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• First metal mined by humans – 8000 years ago • Used in the early development of civilizations

– the Copper Age (3500 – 2300 BC) – tools & weapons – the Bronze Age (3300 – 1100 BC) – tools & weapons

• Malleable metal used in pipe, wire, sheet and strip • Highly prized for its conductivity of electricity • Used as a monetary instrument

Economics of MiningEconomics of Mining

10 円 coin: 95% Cu, 3% Zn, 2% Sn

2012 Copper Uses (Demand)

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33% - Construction

33% - Electronics

13% - Machinery

13% - Transport

8% - Consumer Goods

2012 World Copper Demand – 20,000,000 metric tonnes (44 billion pounds) of copper.

Economics of MiningEconomics of Mining

Where is Copper Found?

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Numerous countries, but most occurrences are small and uneconomic. Most active copper mines are clustered in geologic formations

Economics of MiningEconomics of Mining

2012 Copper Supplies (Sources)

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2012 World Copper Supply – 17,000,000 metric tonnes (34.5 billion pounds) of copper from new mines and 3,000,000 metric tonnes (6.6 billion pounds ) from recycling.

27% - Chile

8% - China

6% - Peru

6% - US

5% - Australia

4% - Russia

3% - Zambia

3% - Congo

3% - Canada

3% - Mexico

19% - Other Countries

15% - Recycled Copper

Economics of MiningEconomics of Mining

2% Copper – Medium –High Grade Mineralization

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2 out of 100 parts (2%) are copper, the other 98 parts (98%) are waste. This is considered medium to high grade for copper .

Mineral Occurrence in the Earth’s Crust verses Mineable Grades

Aluminum 8.2% 49% Iron 6.3% 25% Titanium 0.6% 2% Nickel 0.009% 1%

Copper 0.007% 0.3% Lead 0.001% 0.1% Platinum 0.00006% 0.001% Gold 0.00003% 0.0008%

Economics of MiningEconomics of Mining

Orebodies Are Not Perfect You Typically Cannot Mine 100%

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The extraction of ore usually results in the extraction of significant waste rock as well. This waste must be handled, and in some cases treated.

3:1 Waste to Ore Ratio

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3 tonnes to the waste pile, 1 tonne to the plant for processing. This can alter the economics significantly. Higher grade is always preferred.

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This is the traditional view of the competition between Environmental Concerns, Social Needs, and Economic Desires, resulting in a Sustainable Target Area.

Economics of MiningEconomics of Mining

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However, this is the newer view of the “nested” competition between Environmental Concerns, Social Needs, and Economic Desires, resulting in much larger Sustainable Target Area. This is one of the major challenges in Natural Resource Economics.

Economics of MiningEconomics of Mining

• Used when ore bodies lie near the surface

• Large hole exposes the ore body

• Waste rock (overburden) is removed

• Largest environmental impact

Types of MinesTypes of Mines

Open Pit Mining

• The cheapest and safest method

• The ore is shallow (30m with one or more layers on top of it.

• This mining is done by blasting, then scooping material in narrow strips.

Types of MinesTypes of Mines

Strip Mining

• Very expensive and the most dangerous, but least environmental impact on the earth’s surface.

• Done when the ore deposit is deep, but high grade.

• Entry into underground mines is by vertical shafts, or by a sloping tunnel.

Types of MinesTypes of Mines

Underground Mining

Air pollution: smelters, toxic emissions, dust, noise

Environmental Effects of Environmental Effects of MiningMining

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Environmental Effects of Environmental Effects of MiningMining

Disruption of land surface

Newcrest Ltd Cadia Operations, image shows the result of collapse of the Ridgeway underground mine after removal of stope material.

Environmental Effects of Environmental Effects of MiningMining

Subsidence: sinking of the land

• Waste rock piles have steep angle of repose and thus may not be stable

• Bingham in its hay day produced 400,000 tons of waste rock per DAY.

http://en.wikipedia.org/wiki/Bingham_Canyon_Mine

Erosion of solid mining waste: tailings, spoil banks

Environmental Effects of Environmental Effects of MiningMining

Sulfide deposits react with groundwater to make acid

Acidic streams can pick up heavy elements and transport them as poisonous materials

Acid mine drainage: pollution of water sources as rainwater seeps into ground and surface water

Environmental Effects of Environmental Effects of MiningMining

Environmental Effects of Environmental Effects of MiningMining

Mining IssuesMining Issues

• Anti-mining sentiments:

- visibly uses the land and leaves a profound change

- harmful effects to the environment

- advances greed

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Mining IssuesMining Issues

• Metal Supply

• Depletion of resources

• Present exponential growth is unsustainable

• Drastic measures needed for sustainability

• First test in 30-50 years with depletion of hydrocarbons

(effect in automobile culture & transporation)

• Energy costs will increase, metal prices will increase

• Recycling would be maximized to its practical limits

• Metal recovery from unconventional resources

• New approach to mining: no waste (e.g. waste rock of mines used as construction gravel; multiple commodities in mines)

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Mining IssuesMining Issues

• Reduce consumption – Smaller households, more leisure and travel,

convenience, status etc. make it unlikely even in developed economies

– New technology adds to the existing needs e.g., cellular phones, computers, microwave oven

– In the US, population grew by 65% and consumption grew by 130% between 1950-1990

– Great demand for resources in the developing countries where there is a genuine need and where the great majority lives

• If demand cannot be reduced, supplies must be increased or extended

Mining IssuesMining Issues

• Future supply of metals will come from mixed

sources

Mining IssuesMining Issues

• Mineral deposits locations are predetermined by nature

• Mining without an impact is impossible

• Compromise should be sought – sustainable mining:

- Minimize negative environmental effects

- Improve welfare of affected communities

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Mining IssuesMining Issues