Fossil Fuels

• Rocks in the Earth's crust

  Provide metals, minerals and fuel resources
• Geological processes


  • Gradual and catastrophic processes influence distribution of rocks and minerals in the Earth's crust (lithosphere) and their availability
• Rock


  Solid aggregation of minerals
• Mineral


  A naturally occurring solid chemical element or inorganic compound with a crystal structure, a specific chemical composition, and distinct physical properties
• Mining


  The systematic removal of rock, minerals, soil, or other materials from the Earth's crust for the purpose of extracting resources of economic interest
• Earth's crust composition


  • Chemical elements (silicon, iron, aluminum, calcium, potassium, sodium, magnesium, oxygen, copper, zinc, nickel, cobalt, uranium, phosphorus, etc.)
  • Rock types (ores, minerals - igneous, metamorphic, sedimentary)
• Metal and Mineral Resources are Distributed unevenly
• Some resources (e.g. tantalum and diamonds from DRC - Democratic Republic of the Congo) are considered conflict minerals
• Mined resources


  • Metals (cadmium, nickel, copper, iron, lead, zinc, bauxite, gold, silver, platinum)
  • Rare Earth Elements (neodymium, europium, terbium, dysprosium, yttrium, tantalum)
  • Precious Stones (diamonds, sapphires, rubies, emeralds, jade)
  • Non-metals (asbestos, phosphorus, potassium, sulfur, gravel, sand)
  • Fossil Fuels (coal, oil, natural gas)
• Metal


  A type of chemical element, that typically is lustrous, opaque, and malleable, and can conduct heat and electricity
• Ore


  A mineral or grouping of minerals from which metals are extracted
• Ores


  • coltan (tantalum)
  • pyrite (gold, silver, nickel, copper, zinc, uranium)
• Metal and Rare Earth Element processing after mining

  1. Ores must be pulverized and washed before desired metals/minerals can be physically or chemically extracted

  2. Smelting - process of heating an ore beyond its melting point and combining it with other chemicals to extract a metal
• Non-metallic minerals


  • Gemstones
  • Limestone (calcium carbonate)
  • Salt (sodium chloride)
  • Potash (source of potassium)
  • Sand and gravel aggregates
• Similar mining technologies are used for all resources with similar environmental problems resulting
• Fossil fuels


  Formed under anaerobic environments (in absence of oxygen) from organisms that lived 100 to 500 million years ago
• Types of fossil fuels


  • Coal
  • Oil
  • Natural gas
  • Others
• How coal is formed

  Dead plant matter fell in swampy water, over time more dirt and water washed in which halted the decay process and formed peat. The layers of water and dirt packed down the layers and under heat and pressure, oxygen was pushed out, forming coal.
• Coal mining


  • Similar to most other mining activities (e.g. for metals and minerals) - extractive process
  • Coal is found concentrated in coal "seams" found in an ore
• Mining activity


  1. Systemic removal of surface rock, soil, or other material to extract buried coal deposits

  2. Mining focuses on highest concentrations of coal in surface or underground "coal seams"
• Types of coal mining methods


  • Strip Mining (heavy machinery removes huge amounts of earth to expose and extract resource)
  • Subsurface Mining (underground deposits reached by digging vertical shafts deep underground and excavating networks of horizontal tunnels)
• Mining and Processing Coal have Environmental Costs and Human Health Costs
• Environmental impacts of coal and metal mining

  • Strip mining / open-pit mining
  • Subsurface mining
  • Waste rock (gangue)
  • Tailings
  • Acid mine drainage (AMD)
  • Mountaintop mining
  • Air pollution
• Strip Mining or Open Pit Mining


  • Layers of soil and rock are removed to expose the resource
  • Overlying soil and rock is removed by heavy machinery
  • Used for coal, oil sands, sand, gravel and some metals
  • Destroys natural communities over large areas and triggers erosion and habitat loss, surface and groundwater pollution
• Subsurface Mining


  • Commonly used with coal
  • Deepest mines extend nearly 4 km underground
  • Most dangerous form of mining - dynamite blasts, collapsed tunnels, toxic fumes, coal dust
  • Subsurface mines can affect people years after they close - acid drainage, polluted groundwater, sinkholes
• Waste Rock (Gangue)


  Waste rock and non-valuable minerals removed before extraction (= overburden), used for roads, railbeds, dams
• Tailings


  Ore left over after coal (or metal) has been extracted, pollutes soil and water, may contain heavy metals or acids
• Oxidized Tailings


  Orange colour due to ferric sulfates formed by bacteria that use ferrous sulfides as an energy source resulting in the production of sulfuric acid
• Reduced Tailings


  Black colour due to ferrous sulfides
• Acid Mine Drainage (AMD)


  Sulfide minerals form sulfuric acid and flow into surface waterways and into groundwater, leaching toxic metals from the rocks
• Mountaintop Mining


  • Entire mountaintops are blasted off and the waste is dumped into valleys (valley filling)
  • Economically efficient but environmentally costly - degrades and destroys vast areas, pollutes streams, deforests areas, erosion, mudslides, and flash floods
  • People living in communities near the sites experience social and health impacts - mine blasting cracks foundations and walls, floods and rock slides affect properties, overloaded coal trucks speed down rural roads, coal dust/contaminated water cause illness
• Air Pollution from Impurities in Coal


  • Sulfur, mercury, arsenic, lead and other trace metals released from coal-fired power plants
  • Sulfur content depends on whether coal was formed in salt water or freshwater
  • When high-sulfur coal is burned, it released sulfate air pollutants, which contribute to smog and acidic deposition
  • Mercury can bioaccumulate / biomagnify through food chains/webs
• Reclamation Methods

  1. Governments in developed countries require companies to reclaim (restore) surface-mined sites

  2. Reclamation aims to bring a site to a condition similar to its pre-mining condition - remove structures, replace overburden, fill in shafts, and replant vegetation
• Even on restored sites, impacts may be severe/long-lasting - complex communities are simplified, forests, wetlands, etc. are replaced
• Sulfur content


  Depends on whether coal was formed in salt water or freshwater (e.g. coal in eastern U.S.)
• When high-sulfur coal is burned


  It released sulfate air pollutants, which contribute to smog and acidic deposition
• Mercury


  Can bioaccumulate / biomagnify through food chains/webs
• Ways to reduce pollution must be found (e.g. scrubbers)
• Reclamation Methods

  Restoring Mining Sites can be Very Challenging
• Governments in developed 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