ENV100 Minerals & Water (Week 13 & 14)

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Published on 16 Apr 2013
School
UTM
Department
Environment
Course
ENV100Y5
Professor
Mineral Resources and Mining
Classification of resources
Perpetual (inexhaustible) resources
Non-renewable resources (“wasting” or non-regenerative)
Recyclable resources
Renewable resources
Replenishable resources
Replenishable in principle but requires long time (groundwater & soil); susceptible to mismanagement
“Critical flow” resources: rate of withdrawal>rate of replenishment
Effectively become non-renewable; Systems approach: is outflux greater than influx?
Earth Resources and living resources
Earth resources extracted from the solid Earth, non-renewable on a humanly accessible scale
Management approach: conservation, efficiency, 3Rs
Living resources are living, growing, regenerating populations (fish & trees); renewable in theory
Management approach: stock and flows
Critical flow resources (effectively non-renewable because of mismanagement)
Common property resources
Other (human resources, ecological knowledge, etc.)
Will we run out?
Live in closed system but Earth resources very large
Static lifetime: Lifetime expectancy of a resource at current rates of production and use
Difficult to calculate (lying, the enormous size of resources and large scale operations)
Mineral Resources
Rock: Solid aggregation of minerals
Mineral: naturally occurring solid chemical element or inorganic compound with a crystal structure, a specific
chemical composition, and distinct physical properties (i.e. tantalite with elements: oxygen, iron, manganese, tantalum)
Mining: systemic removal of rock, regolith, or other materials for purpose of extracting minerals for economic
Deposit: natural occurrence of a resource
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Grade: level of concentration of ore in a deposit
Ore: economically valuable material in a deposit
Native: un-combined with other elements
Gangue: waste rock and non-valuable minerals
Factors affecting mineral deposit life
Discovery of new resources increases known reserves
New extraction technologies reach more minerals at less expense
Changing social and technological dynamics modify demand in unpredictable ways
Changing consumption patterns affect how fast we exploit reserves (e.g. recession reduces demand)
Recycling extends lifetime of mineral resources
Minerals metal/non-metal
Metal: chemical element that is shiny, opaque, malleable, and conducts heat and electricity
Precious metals (gold, silver, platinum), base and ferrous metals (iron, nickel, copper, zinc, etc)
Non-metal: basically everything else
Fertilizers, salt, building stone, aggregates, clay, asbestos, gemstones, uranium and other fuels, etc
Types of Mines
Underground (subsurface) mines
Zinc, lead, nickel, tin, gold, diamonds, phosphate, salt, coal, uranium, etc.
Acid drainage, polluted groundwater, sinkholes damage roads and homes
Surface mines
Open-pit mine
Copper, iron, gold, diamonds, coal
Quarries: open pits for clay, gravel, sand, and stone (limestone, marble, granite, and slate)
Habitat loss, aesthetic degradation, acid drainage (abandoned pits fill with toxic water)
Strip mine
Strip mining: layers of soil and rock are removes to expose resource
Overburden: overlying soil and rock that is removed by heavy machinery
After extraction, each strip is refilled with overburden
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Mainly for coal, oil sands, sand, gravel
Destroys natural communities over large areas and triggers erosion, cause acid mine drainage
Mountaintop removal
Mountaintops blasted off and rock put into valleys (valley filling); economically efficient
Pollutes streams, deforests areas, erosion, mudslide, flash flood
Placer operations
Using water, miners sift through material in riverbeds; used for gold and gems
Debris washed into streams makes them uninhabitable for wildlife
Acid mine drainage: sulphide minerals form sulphuric acid and flow into waterways
Affects both surface and subsurface mines
As acid runs off, it leaches metals from the rocks, many of which are toxic; formed liquid called leachate
AMD probably biggest problem associated with mining in Canada
Effluent: any contaminated liquid runoff
Solution mining (in-situ recovery): resources in a deep deposit are dissolved in a liquid and siphoned out
Can be surface or subsurface; salts, lithium, boron, bromine, potash, copper, uranium
Less surface area disturbed than in other methods
Acids, heavy metals, uranium can leak into ground water; subsidence, ground collapse
Some minerals found on ocean floor: sulphur, phosphate, calcium carbonate, silica, copper, zinc, silver, gold
Manganese nodules: small, ball-shaped ores scattered around the ocean floor; mining uneconomical
Hydrothermal vents may have gold, silver, zinc
Mining affects air, land, water, health
Air: Pollution from smelting and refining
Dust from waste rock and tailings piles
Land: Construction of roads and buildings
Stripping of surface vegetation and soil
Mine shafts and excavation pits
Ground subsidence
Rock waste and tailings piles
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Document Summary

Replenishable in principle but requires long time (groundwater & soil); susceptible to mismanagement. Critical flow resources: rate of withdrawal>rate of replenishment. Earth resources extracted from the solid earth, non-renewable on a humanly accessible scale. Living resources are living, growing, regenerating populations (fish & trees); renewable in theory. Critical flow resources (effectively non-renewable because of mismanagement) Live in closed system but earth resources very large. Static lifetime: lifetime expectancy of a resource at current rates of production and use. Difficult to calculate (lying, the enormous size of resources and large scale operations) Mineral: naturally occurring solid chemical element or inorganic compound with a crystal structure, a specific chemical composition, and distinct physical properties (i. e. tantalite with elements: oxygen, iron, manganese, tantalum) Mining: systemic removal of rock, regolith, or other materials for purpose of extracting minerals for economic. Grade: level of concentration of ore in a deposit. New extraction technologies reach more minerals at less expense.

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