Mining

From the topic outline IV. Land and Water Use Mining (Mineral formation; extraction; global reserves; relevant laws and treaties)

14.3 What Are Mineral Resources and What Are The Environmental Effects of Using Them? Some naturally occurring materials in the Earth’s crust can be extracted and made into useful products in processes that provide economic benefits and jobs. Extracting and using mineral resources can disturb the land, erode soils, produce large amounts of solid waste, and pollute the air, water, and soil.

Bellwork If your group had been able to secure site 16 for mining of Molybdenum, what would be your next step? What type of mine would you most likely have? To whom would you sell the molybdenum? (Hint: use your device to research possible answers!) What is reclamation?

Minerals Mineral Resource: Naturally occurring, inorganic, material from crust Ore: Rock that contains a large concentration of a mineral High Grade Ore: Large amount of mineral Low Grade Ore: Smaller amount of mineral

Ore Examples If you can’t grow it, you have to MINE it! Element Ore Silicon Quartz Aluminum Bauxite Iron Magnetite or Hematite Calcium Gypsum or Calcite Sodium Halite Magnesium Magnesite or Dolomite Potassium Sylvite Copper Chalcopyrite Tin Cassiterite Lead Galena Zinc Sphalerite

Cookie Mining Mining for chocolate ore You control your profits Choose your “land” (cookie) Choose your tool(s) Determine how best to mine and how achievable reclamation will be You will be charges for any land that is not reclaimed

Important Minerals and their Uses

Estimating Mineral Resources Key terms used by USGS: Identified: location, quantity, and quality known based on direct measurements. Undiscovered: potential supplies assumed to exist. Reserves: identified resources that can be extracted profitably.

Effects of Mineral Use No matter the mineral, all steps use large amounts of energy and creates pollution. High grade = less energy needed Low grade = more energy needed

Environmental Effects environmental effects, cont. toxic chemicals can also be emitted to the atmosphere metal ores are extracted, purified, smelted, and made into desired products ore consists of ore mineral and gangue ore is separated from gangue, smelted to obtain the metal, and made into products that are used and discarded or recycled there can be enormous amounts of air and water pollution from these processes

Harmful Effects

Environmental Effects mining, processing, and use of mineral resources uses large amounts of energy, causes land disturbance, and air and water pollution land is scarred and the surface is disrupted; cleanup may cost billions subsidence from underground mining can cause pipelines to break mining wastes contain toxins, and acid drainage contaminates streams and groundwater

Fig 16-14 Pollution of water from mining

Environmental Effects environmental effects, cont. toxic chemicals can also be emitted to the atmosphere metal ores are extracted, purified, smelted, and made into desired products ore consists of ore mineral and gangue ore is separated from gangue, smelted to obtain the metal, and made into products that are used and discarded or recycled there can be enormous amounts of air and water pollution from these processes

Environmental Effects Disturbs large area Prone to erosion Uses large quantities of water Must pump water out of mine to keep it dry Acid Mine Drainage (AMD) Pollution caused when sulfuric acid and dissolved lead, arsenic or cadmium wash out of mines into nearby waterways

Environmental Effects of Gold Mining Gold producers South Africa Australia United States Canada Cyanide heap leaching Extremely toxic to birds and mammals 2000: Collapse of a dam retaining a cyanide leach pond Black Hills : S. Dakota

Acid Mine Drainage

Finding, Removing, Processing promising underground deposits of minerals are located by a variety of physical and chemical methods methods include aerial photographs, satellite images, radiation-measuring equipment, magnetometer, gravimeter underground methods are also used such as seismic surveys, analyzing shock waves from explosive charges, and use of chemical analysis of water and plants for leached materials

Extracting Minerals from Deposits Surface Mining Remove overburden (discarded as spoils) to get to mineral deposits Types Open-Pit Strip Contour Strip Dredging Mountain-Top Removal

Open Pit Mining Machines dig large holes in ground, remove ores Toxic water can collect at bottom of pit

Strip Mining Similar to open-pit, but only useful when deposits are horizontal and near surface

Specific kinds of surface mining Open-pit mining Strip mining Holes are dug Ores are removed Iron, copper, gold, sand, gravel, stone Used for horizontal beds of minerals Area strip mining: flat land Contour strip mining: hills Coal (70%)

Contour Strip Mining Used in hilly or mountain areas Cut terraces Remove overburden and use to make new terrace

Dredging scrapes up underwater mineral deposits

Mountain-Top Removal Literally remove the top of mountains (!!!)

Surface mining method: mountain-top removal Mountain top removed Exposes deposits Prominent in Appalachian mountains Ex. Coal

Mountain-Top Removal Example

Eureka! Gold Mining Placer Deposits (gravity separation) Panning Sluicing Dredging Hard Rock Deposits Open pit Hydraulic mining (sometimes with Hg) Subsurface - S. Africa 12, 800 feet underground Cyanide is used to extract gold In comparison - Mt Baldy is 12441 ft

Removing Metals from Ores Negative consequences: Scarring/disruption of land surface Large amount of spoils Large amounts of solid waste Toxic or acidification of water (H2SO4, etc.) Gangue (“gang”) Air pollution

14.4 How Long Will Supplies of Nonrenewable Mineral Resources Last? All nonrenewable mineral resources exist in finite amounts, and as we get closer to depleting any mineral resource, the environmental impacts of extracting it generally become more harmful. An increase in the price of a scarce mineral resource can lead to increased supplies and more efficient use of the mineral, but there are limits to this effect.

Depletion of Resources Future supply depends on two factors: Actual supply Rate of use Depletion time Use up 80% of resource After depletion: Recycle, waste less, use less, find a substitute, do without

Economic Depletion As known resources are depleted, it becomes more expensive and difficult to get to new supplies We might still have resources left, but it will be TOO COSTLY to utilize them on a wide-scale

U.S. General Mining Law of 1872 To encourage mining of “hard rock” minerals How it works: File claim that you believe land contains valuable minerals Promise to spend $500 to improve it Purchase public land for $2.50 to $5.00 an acre (!!!) Pay $120 a year for each 20-acre parcel of land Law frozen in 1995 – by that time, estimated $285 billion of public land “given away” at 1872 prices Since clean up requirements only came in 1992, there are an estimated 500,000 sites that will cost taxpayers $32-72 billion to clean up!

Example of 1872 Law “Give Away” In 2004, a mining company purchased 155 acres of public land near Crested Butte for $875 Land could be worth $155 million Each year, companies remove $4 billion worth of minerals each year and only pay 2.3% of the value in tax (compared to 13.2% for oil or 14% for grazing rights)

14.5 How Can We Use Mineral Resources More Sustainably? We can try to find substitutes for scarce resources, reduce resource waste, and recycle and reuse minerals.

Reclamation The good news: Mining now requires reclamation Reclamation: Returning the land as close as possible to original state.

Copper Basin, TN

Surface Mining Control and Reclamation Act of 1977 requires mining companies to restore most surface-mined land reclamation efforts are only partially successful subsurface mining removes coal and various metal ores too deep for surface mining subsurface mining disturbs less than 1/10 as much land as surface mining with less waste, but is more dangerous and expensive

Restoration of Mining Land Creative Approaches Wetlands Trap and filter pollutants before they get into streams Initially expensive, but cost effective compared to using lime to decrease acidity Phytoremediation Use of specific plants to absorb and accumulate toxic materials in soil

Industrial Ecosystems Design industrial process to mimic nature

Uneven distribution of minerals Most of the nonrenewable mineral resources supplied by Canada United States Germany Russia South Africa: self sufficient in all key minerals, largest producer of gold, chromium and platinum Australia 8% of world population, consume 75% of the world’s key metals China increasing consumption

Minerals in Antarctica No substantial mineral deposits identified to date Antarctica Treaty (1961) Limits activity to peaceful uses (i.e., scientific studies) Madrid Protocol (1990) Moratorium on mineral exploration and development for minimum of 50 years

Finding Mineral Substitutes Important goal in manufacturing Substitute expensive/scarce mineral resources for inexpensive/abundant ones Examples: Using plastic, glass or aluminum in place of tin Using glass fibers instead of copper wiring in telephone cables

Mineral Conservation Includes reuse and recycling of existing mineral supplies Reuse - using items over and over again Reduces both mineral consumption and pollution Recycling - converting item into new product Reduces land destruction from mining Reduces solid waste