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Mineral and Rock Resources
Chapter 13
Sulfur crystal, Sicily
photo by J. Carr
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Ore Deposits
Orerock in which a valuable or useful
metal occurs to be economic to mine
Concentration Factor(CF): CF = Cm/Cmc Cm = Concentration factor of the metal in the ore
Cmc = Concentration of the metal in average
continental crust
The higher the CF - the richer the ore
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Examples of Metals obtained from Ores
Aluminum or Ironappliances andvehicles
Metals for conductors or semi-conductors
Gems, gold, and silverjewelry
Lead from galena
Copper from malachite and azurite
Zinc from sphalerite
Many other metals found in rocks
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Cost Factors
Concentration Factor (CF)
4 to 25,000 times CF
highly variable occurrences
World demand and many market factors
Energy cost
Human/labor cost
Distance to processing or market
Environmental cost - remediation
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Distribution
Globally, very un-even distribution
Some countries have plentyexport nations
Some countries have noneimport nations
Figure 12.1
Un-even distribution is reason wars are
fought
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Types of Mineral Deposits Igneous Rocks and Magmatic Deposits
Pegmatite Kimberlite
Hydrothermal Ores Veins
Relationship to Plate Margins
Sedimentary Deposits Banded iron formation
Evaporite Other low-temperature ore-forming processes
Placers
Metamorphic Deposits
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Mineral and Rock Resources
Examples (the ways we use)
Metalsiron, aluminum, copper, lead,zinc, nickel, cobalt, gold, silver, or platinum
Nonmetallic Mineralssulfides, lime
(calcium carbonate), sulfur, halite, clay,gypsum, or potash
Rock resourcesmost abundant quantity
of earth resources we use Sand, gravel, limestone, quartz-rich sand,marble, granite, and sandstone
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Mineral Supply and Demand
Global demand is always growing
About 2% pre-World War II for most metals
About 10 % World War II to mid-1970s
Demand is fluctuating now
U.S. Mineral Production and Consumption
U.S. population is only 4.5% of the world but
consumes many times its share of the world
supply
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World Mineral Supply
World demand is always fluctuating
Commodities do not follow fluctuatingtrends
Mineral reserves eventual will be depleted
Import/export relationships will fluctuate
Technology often allows more access to
difficult or low grade ore deposits Future mineral-resource shortages will
occur and cause international tension
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Minerals for the Future
Some Options Considered
Consider controlling consumption rates Reduce the consumption rates (unlikely)
Hold these rates steady (unlikely)
Carefully consider the facts: Globally the less developed nations are strivingto achieve comparable standards of living as
the technologically advanced countries enjoy
Countries that have the fastest-growingpopulations are not well endowed with mineral
deposits and are the less developed countries
of the world!
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New Methods in Mineral Exploration
Fact: the economically easy and profitabledeposits are being depleted
Geophysics is a useful aid to locating newdeposits
Gravity survey Magnetic survey
Electrical property survey
Geochemical survey and prospecting is anincreasingly popular exploration tool
Remote sensing is expanding intoexploration strategies
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Remote Sensing Sophisticated but valuable exploration tools
Useful to detect, record, and analyze energyemitted off the earth Aerial photography
Satellites
Space shuttle, and other manned missions
Remote sensing is backed up by ground truthactivities
old fashioned geologic mapping Advances in the geological sciences are
directed toward intigration of remote sensing,geochemistry, and geophysics
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Marine Mineral Resources Oceansour new mineral frontier
Sea water contains abundant dissolved mineralsand many useful element Most extraction techniques currently used are energy
intensive and expensive
Hydrothermal ore deposits along seafloorspreading ridges are a possible source of manymaterials Currently, they are too deep - of limited benefit
Manganese nodules are widely distributed onthe ocean floors; a promising solution. Many political, environmental, and legal obstacles
must be over come before they can be mined
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Fig. 12.20
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Conservation of Mineral Resources
Overall need for resources is growingmustreduce this expansion
Some mineral resources maybe substituted by
other, more abundant resources
Plastics replacing automobile parts
Recyclingmany metals are successfully
recycled
More recycling is required Not all commodities are easy to recycle
Measures to reduce demand must be the key
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Impacts of Mining Activities
Mining and mineral-processing activities canmodify the environment in various ways
Both underground mines and surface mineshave their own sets of associated impacts
Safety, hazards, and water and air pollutionshould not be overlooked
Very stressful to the environment
Must be carefully planned Must be safe to miners and their neighbors
Must be containedwater and air pollution is amajor problem
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Underground Mines
Generally hard to see where they are locatedArea of disturbance is local
Miners place the tunnels close to the ore body to
cut down on waste Once mines are closed they can be sealed with
the non-ore rock (waste rock)
Surface collapse general limited and controllable
with modern mine reclamation practices
Old, abandoned, and forgotten mines are still
a problem
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Surface Mines
Quarrying extracts rock to be used either intact
(building blocks or facing stone) or crushed(cement-making and road bed)
Open-pit Mine a large ore body located near the surface
Permanent changes to local topography will occur
Strip mining Most ores occur in a layer that generally is parallel to
the surface
The ore zone is overlain by vegetation, soil, non-ore
rock that must be removed Spoils banksare designed to collect the waste rock
Current reclamation law requires that it be return tothe pit and the original soil replaced
Expensive but vital
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Fig. 12.25
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Mineral Processing Mineral extraction is environmental hazardous
Ore rock is ground or crushed for extraction The fine waste material is placed in tailings
The tailings are exposed to wind and weather
Harmful elements such as mercury, arsenic,
cadmium, or uranium can leached out The surface and subsurface water systems are too
often contaminated
Chemicals used in ore extraction must be controlledand not just dumped
Smelting ores to extract metals, often produce metalladen exhaust gas or ash, sulfur oxid,e and acid rainpollution
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