Chapter 27 Minerals and the Environment Mining Removal

Chapter 27 Minerals and the Environment

Mining • Removal of minerals & fossil fuels from the Earth’s crust.

Mining methods depend on: • Depth of resources • Amount of stability of material that must be removed (overburden) to reach the mineral • Topography • Safety • economics

Surface (strip) mining • Removes deposits that lie in horizontal bed’s close the earth’s surface – Land is clear-cut – Overburden removed – Deposit is removed – Overburden replaced • Long term environmental damage

Mountaintop Removal • Type of surface mining – Coal • Coal seams are exposed by removing the tops of mtns. , using explosives and/or heavy equipment • Overburden dumped into adjacent valleys • Coal removed • Fed. Law requires reclamation – Topography is never really restored

Open Pit Mining • Huge hole dug using explosives & heavy equipment • Deposit is removed • Pit is often filled with water that becomes acidic or polluted with heavy metals from mine waste

Open Pit – Uranium Mining

Subsurface Mining • Deep vertical mine shafts with horizontal tunnels branching off • Used when deposits are too far underground to be reached by surface mining • Less habitat destroyed • Much more dangerous – Cave-in, collapse, explosions, poisonous gases – flooding

Drilling • To remove liquids and gases • Deep shafts drilled into the earth to reach geologic formations • Pressure usually forces the liq. Or gas to surface – If no pressure, water or steam is injected

Environmental problems with drilling • Platforms destroy habitat at surface • Liquids are susceptible to leaks & spills • Pipelines that carry liquids or gas result in habitat loss

US Mining Laws • The General Mining Law of 1872 – Encourages the exploration & mining of mineral resources – Allows corporations to acquire large tracts of public land below market value – Corporations can remove valuable mineral without paying adequate royalties or sufficient cleanup

The Surface Mining Control & Reclamation Act of 1977 • Mined land must be restored to pre-mined state – Disposal of waste – Re-contouring land to get back topography – Replant native vegetation

How Mineral Deposits Are Formed • Ore Deposits – formed when metals are concentrated in anomalously high amounts by geological processes • Mineral resources are usually extracted from ore deposits

Resources and Reserves • Minerals are classified as: – 1. Mineral Resources • Elements, chemical compounds, minerals or rocks that can be extracted to obtain a usable commodity • The combination of reserve. – 1. Mineral Reserves • The portion of the resource that is identified and from which usable materials can be legally and economically extracted at the time of evaluation

Availability of Mineral Resources • When the availability of a mineral becomes limited, there are 4 possible solutions: 1. Find more sources 2. Recycle and reuse what has already been obtained 3. Reduce consumption 4. Find a substitute

Impacts of Mineral Development • Environmental Impacts – Depends on many factors – mining procedures, climate, rock type, etc. • Social Impacts – Increased demand for housing and services in mining areas

Minimizing Environmental Impact of Mineral Development • Environmental regulations at the federal, state and local levels • On-site and off-site treatment of waste • Practicing the 3 R’s of waste management

Minerals and Sustainability • R-to-C Ratio – A measure of the time available for finding the solutions to depletion of nonrenewable resources – R = known reserves – C = rate of consumption