Enduring Understanding:

• When humans use natural resources, they alter natural systems.

Learning Objective:

• Describe natural resource extraction through mining.

• Describe ecological and economic impacts of natural resource extraction through mining.

Essential Knowledge:

• As the more accessible ores are mined to depletion, mining operations are forced to access lower grade ores.  Accessing these ores requires increased use of resources that can cause increased waste and pollution.

• Surface mining is the removal of large portions of soil and rock, called overburden, in order to access the ore underneath.  An example id strip mining, making the area more susceptible to erosion.

• Mining wastes include the soil and rocks that are moved to gain access to the ore and the waste called slag and tailings that remain when the minerals have been removed from the ore.  Mining helps to provide low cost energy and material necessary to make products.  The mining of coal can destroy habitats, contaminate ground water, and release dust particles and methane.

• As coal reserves get smaller, due to a lack of easily accessible reserves, it becomes necessary to access coal through subsurface mining, which is very expensive.

Mining

• Mining is obtaining minerals from the ground

  • This can be gold, diamonds, phosphorous-bearing rock, gravel, coal, and more

• Refining is an industrial process that removes impurities from a substance

  • Minerals don’t come out of the ground ready to be used, they have to be altered and cleared of impurities in some way

  • This process varies depending on the product

  • The amount of impurities can also vary, changing the amount of work needed to reach the desired purity

  • Note that the more refining needed, the more energy used, which will have all the consequences of fossil fuel use as well

• Minerals are finite resource

  • Logically, the highest quality material is extracted first, but eventually that will run out and lower quality raw materials will have to be used

Types of Mining

Surface Mining

• Open-pit mines are an example of this

• Instead of mining on a flat plane, you mind in levels downward

  • Once each level is depleted, you mine another layer down

• Strip mining is… mining in strips

• Also note all of the machinery that is going into these processing and how much fossil fuel energy is going into powering them

• Mountaintop removal is a type of mining that is particularly disruptive

  • As the name suggests, the top of a mountain is blown off and the minerals are extracted

  • It’s typically in pursuit of coal

Subsurface Mining

• What most people think of, but its actually not the first choice

• Hazardous due to the precarious nature of being underground

• Particulate matter in the air can harm human respiratory health

  • Black lung disease

• Expensive

After Extraction

• Ore is refined in various ways to become the target mineral

• During refinement, impurities accumulate as tailings

• Tailings are piled like spoils and abandoned

Cyanide Heap Leaching

• A liquid including cyanide is poured over ore

• The impurities are dissolved into waste slurry

• The target mineral is removed from the slurry, gold in this case

• What happens to this cyanide-laced slurry?

  • It has to be disposed of somehow, and there really isn’t a great way to do that

Consequences

• Rock that is mined out but not desirable is called spoil

• Overburden is the material on top of the ore that needs to be removed

  • Once it is removed and placed away, it is spoils

  • Same stuff, different place

• With open-pit and mountaintop removal mines, keep in mind the environmental consequences of open earth, disturbed habitats, a slope with no vegetation, lowered albedo, etc.