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CA (620,000)
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ENV100Y5 (900)
Lecture 35

ENV100Y5 Lecture Notes - Lecture 35: Heavy Metals, Siltation, Conflict Resource

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Hevalkaand Murck

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ENV100Y5- Lecture 35- Mineral resources and mining
Different stages of mining:
Exploration stage:
Generally the lowest environmental impacts
Relatively low impacts
Habitat disturbance
Noise from flyovers
Discharge of contaminants from drilling, trenching, road access
Mining/Milling stage:
Mining and milling can have more significant impacts
Dust, noise
Land disruption
Increased erosion, siltation
Acid mine drainage
Heavy metals in ore and tailings
Organic compounds in chemical reagents - Cyanide, ammonia used to separate
ores - Waste rock piles and tailings
Smelting/Refining stage:
Can have significant impacts, especially on air
Discharge of airborne contaminants, including heavy metals; organics; sulphur;
etc. - Slagheaps
Indirect effects from energy use
Post-Operational stage:
Happens after mine has closed
Depends on management effectiveness
Discharge of contaminants to surface water
Left over equipment, radiation, etc.
Social and economic impacts–“ghost” towns
Restoring mined sites can be very challenging:
mine operation is shut down
return the site to a condition similar to its pre-mining condition
Remove structures, replace overburden, fill in shafts, and replant vegetation
Governments in some countries require companies to reclaim (restore) surface-
mined sites
In Canada, companies are required to post bonds to cover reclamation costs
before mine development is approved
Some countries (e.g., Congo) have no regulations
Even on restored sites, impacts may be severe and long- lasting
Water can remain polluted
Complex communities are simplified
Forests, wetlands, etc. replaced by grasses
Essential symbioses are eliminated and often not restored
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