Topic 3: (midterm 2 start)

Question 1

What are some of the environmental impacts on ore processing?

Answer 1

• noise and dust
  (typically closer to the mine, crushing ore down to sediment level affects air and water quality)
• tailings pollution
  (fine grained tailings carried away in water systems, tailings dumped on landscapes or rivers.

Question 2

What are some of the methods of smelting?

Answer 2

• reduction of oxides (carbon monoxide from incomplete combustion of coke reacts with iron oxide at high temps, produces iron and co2)
• roasting (taking sulphides, heating them, turns them into oxides - then smelt after)
• conversion (ores smelted directly to produce a matte)
• distillation (metal vapour evaporated and then condensed at later stages of extraction process)

Question 3

What is smelting?

Answer 3

isolation of pure metals from ore minerals

Question 4

What are some of the environmental impacts of smelting?

Answer 4

• Air pollution!!!:
• stuff melts and evaporates that we don’t need or want in our ores, if they don’t end up in slags they end up in the air.
• particulates or aerosols travel long distances in air, concentrate in rain and snow, bioaccumulate in food chain

Question 5

what is hydromettallurgy?

Answer 5

• type of resource mining using heap leaching
• typically the dissolution of gold using cyanide solutions
• crushed ore rock is piled on impermeable membrane, cyanide is sprayed over it and dissolves the gold
• slow percolation! can take several months!

Question 6

What are the environmental impacts of hydrometallurgy?

Answer 6

• cyanide is highly toxic, so if it leaches past the impermeable membrane can pollute the environment
• ex. Summitville, Colorado, and Eagle mine in Yukon

Question 7

What are the main pollutants of fossil fuel combustion?

Answer 7

• Carbon monoxide
• carbon dioxide
• hydrocarbons
• oxides of nitrogen and sulfur
• particulates, such as ash and soot
• photochemical smog

Question 8

What is photochemical smog? What situations is it produced under?

Answer 8

• produced from fossil fuel combustion
• where hydrocarbons and nitrogen oxides react in lower atmosphere in presence of sunlight and still air
• requires sunny conditions, cold air, and high traffic volumes
• cold air traps smog below layer of warmer air so it cant escape

Question 9

What is the behavior of ground-level atmospheric pollutants? What are atmospheric inversion layers

Answer 9

• behavior of atmospheric pollutants is dependent on atmo conditions and temperature structure
• atmo inversion layers are where there is warm air over cold air, warm exhaust gas rises until it meets air of similar temp and density, cold air stays below as it is more dense
• exhaust gasses may not penetrate the inversion layer, and becomes trapped in a low level smog

Question 10

What are the harmful effects pf air pollution?

Answer 10

• reduced visibility
• discoloration of buildings and trees
• major health effects (such as from lead, carbon monoxide, PM10’s, and hydrocarbons)
• climatic effects (can cool as particulates can increase albedo, or warm as CO2 is a greenhouse gas )

Question 11

What are some of the consequences of climate change?

Answer 11

• temperature rising
• sea level rising, thermal expansion and ice melt
• sea-ice loss
• glacier and snow cover retreat
• changes in global precipitation zones
• more intense and northward hurricanes
• more extreme weather variation

Question 12

What is ozone depletion? What causes it?

Answer 12

• marker loss of ozone over both poles
• due to CFC (chlorofluorocarbons) reaction in atmosphere
• CFC’s used as cheap propellant in spray cans, or in electronics, etc.
• if released into the air, it migrates to the stratosphere, concentrates at poles, which eventually leads to destruction of o3