apes mining

MINING

• Earth’s crust = 45% O, 27% Si, 8% Al

• Terms

  • Ore: concentrated accumulations of minerals from which economically valuable materials can be extracted

  • Overburden: soil and rock that covers the ore (land that needs to be removed before excavation)

  • Metals: Elements that can conduct electricity & heat (Cu, Ni, Al, Au)

  • Reserve: Known quantity of a resource that can be recovered

  • Spoils: materials removed to extract ore (the rock that is removed to access ore)

    • Spoil banks: holes that were filled with waste (cheap & easy; susceptible to erosion, causes sediment runoff)

  • Gangue: unwanted part of the ore; left over after extracting valuable minerals (after processing)

  • Tailings: piles of gangues (after the gangue is processed and finely ground)

  • Subsidence: gradual collapse of land due to underground coal mining

  • Rare earth metals: Sc, Y, lanthanides

    • Sc: alloys with Al, used in tech, baseball bats, and military jets

    • Widely distributed throughout rocks concentrated enough to get a commercially viable deposit

• Types

  • Surface: cheap, safe, very destructive

    • Open-pit mining: large visible pit (ex. quarries)

      • Material is removed using large equipment

      • Resource is close to surface

      • Degrades landscape, affects air and water quality

    • Strip mining: removes strips of soil and rock

      • Similar to open-pit, but not as deep

      • Remove material, extract resource, return spoils / tailings

      • Area strip mining: flat terrain (can cause erosion)

      • Contour strip mining: mountainous areas (terraces are cut into the mountain)

    • Mountaintop removal: uses explosives to expose seams of minerals

      • Tailings are deposited in nearby regions

      • Causes deforestation and carbon emissions (burning of coal)

    • Placer mining: looking for minerals / metals in river sediments

  • Subsurface: expensive, dangerous, less damage to the environment

    • Underground coal mining: open shafts into the earth that “follows” the coal

      • AMD can drain out of mines

      • The ground above each shaft could collapse 

    • Room and pillar: pillars of coal are left to support the cavern, creating “rooms” of coal (to prevent collapse)

      • Can cause water pollution and changes in groundwater flow patterns

    • Longwall mining: extracts minerals using a shearer

      • Good for ores that form horizontal deposits

    • Shaft mining: vertical tunnel straight into the deposit

      • Top of excavation is at the ground surface = shaft

      • Top of excavation is underground = winze / subshaft

    • Slope and drift mining (for coal)

      • Slope = diagonally sloping access shafts

      • Drift = Horizontal access tunnels

    • In situ: for radioactive U

    • Dredging: sand is removed from the ocean floor

      • Can be used to restore beaches

      • Destroys benthic ecosystems

    • Solution mining: pumping water into subsurface mineral deposits to bring dissolved minerals to the surface

    • Hydraulic fracturing: fracking

      • Creates fractures in rock by injecting a fluid that forces them open

      • Allows more oil and gas to flow out

    • Mine adit: entrance to an underground mine; serves as an entrance, drainage area, tunnel ventilation

• Steps

  • Prospecting: finding places where there is ore

  • Mine exploration & development: whether the ore can be extracted economically

  • Mining: extraction of ore

  • Beneficiation: separate ore from rock

  • Smelting / refining: extract pure mineral from ore

    • Heat bleaching: takes low grade ore and extracts / concentrates the rare earth metals they contain

  • Transportation: brining mineral to market

  • Marketing & sales: finding buyers to sell the mineral

• Impacts

  • Air: Dust particles, methane / CO₂ (fossil fuels)

  • Soil: increases erosion (loss of vegetation), loss of topsoil in strip-mined regions

  • Biodiversity: habitat destruction

  • Health: Increased regulation to reduce health risks

    • Mine collapse, fire, asphyxiation, pneumoconiosis, asbestosis, silicosis, metal poisoning (especially Hg), radiation exposure

    • Black lung: comes from inhaling coal dust (type of pneumoconiosis - CWP)

  • Water: contamination as a result of tailings, accidental drainage of rivers/lakes

  • Acid Mine Drainage (AMD): formation of acidic water in heavy metals

    • Can react with water to form sulfuric acid

    • pyrite + O₂ + H₂O = Fe(OH)₃ + SO₄ + H⁺      (NOT ON TEST)

      • pyrite + oxygen + water = iron (iii) hydroxide + sulfate + hydrogen ions

    • Different AMD flows in different mines have different amounts of rare earth metals because different plants / sediments were compressed into the coal

    • Has a heavy rare earth metal : total metal ratio of ~50% (largest mine only has a ratio of ~12%)

    • Treatment:

      • Add lyme to AMD to form a slurry (thin mix of liquid and sludge that will flow)

      • Moves through a clarifier, where the heavier particles and sludge settle to the bottom

      • Water moves to get treated, sludge goes to geotubes

        • Massive expensive for treatment (Can’t be thrown into a landfill because it can contaminate groundwater supplies)

        • Lets the water flow out, but keeps solids in

        • One tube has ~ $11,000 of rare earth metals

• Regulation

  • MSHA (Mine Safety and Health Administration) enforces health standards

  • Mining Law of 1872 (General Mining Act):

    • Allows individuals / companies to recover ores and fuels from federal lands

    • Few provisions for environmental protection

  • Surface Mining Control and Reclamation Act (1977)

    • Land must be minimally disturbed during coal mining, then reclaimed

    • Regulates the environmental effects of coal mining

    • Created two programs to reclaim abandoned mines and to regulate active mines

    • Related laws: 

      • Clean Air Act: regulates air emissions

      • Clean Water Act: regulates discharge of pollutants into water

      • Superfund Act: tax on chemical / petroleum industries

• Resources

  • Metallic (ex. Au, Cu, Pd), non-metallic (ex. sand, gravel), energy resources (ex. coal, U)

  • Mineral reserve: economically mineable part of a measured mineral resource

    • Proven reserve: offers >90% probability of successful extraction

    • Probable reserve: ≥50% probability of extraction

    • Possible reserve: unproved deposits; probability of successful extraction ≥10%

  • Sustainability

    • Recycling items with important heavy metals

    • Reducing the amount of heavy metals in products (more efficient usage)

  • Economic Mineralogy

    • Minerals are important in domestic & international commerce

    • Gold, silver, diamond = jewelry, electronics, grinding 

    • Gypsum, calcite = construction

    • Copper, hematite = electronics, manufacturing

    • Clay minerals = clay industry

    • Biggest consumers: US, Japan, Europe

    • Biggest producers: South America, South Africa, Russia, CHINA

    • Blood diamonds

      • Diamonds mined in a war zone and sold to finance war efforts

      • Includes diamonds mined during civil wars in Angola, Sierra Leone, and the Ivory Coast