D. Shell, SMHS 2013

OPEN-PIT

STRIP

Contour

Strip

Mineral = naturally occurring elements & compounds (PURE)

nonmetallic minerals w/ economic value include graphite, quartz crystals, diamonds, gems, sand, gravel, limestone, salt, phosphate, SULFUR.

metals extracted from earth & consumed most: Fe, Al, Mn, Cu, Cr, Ni.

most minerals are not found pure, but are mixed with other minerals in ROCKS

Alloys – metals mixed, melted or fused together with other metals to make a product that is more useful than its parts (ex: bronze, brass, coins, jewelry, steel)

Ore = rocks with enough minerals in them to mine at profit (iron ore, etc.) o high grade ores = lots of minerals = very profitable = mineral reserve o low grade ores = few minerals = not profitable now = mineral resource

Mineral Formation 1. Magmatic concentration: minerals formed in layers as magma cools (heavy near bottom (iron oxides) & light near top(silicates)) 2. Hydrothermal processes: hot water near magma dissolves minerals as it passes thru rock layers below surface & then deposits

them where hot water breaks thru surface 3. Sedimentation: rivers / surface water dissolve minerals and deposits them in new spots 4. Evaporation: as water evaporates out of the ocean or lakes, the water leaves into the air & any minerals dissolved in it are

deposited on the bottom. Extraction: Steps to convert mineral deposit to usable product

1. locate deposit: aerial or satellite imaging; measure Earth’s magnetic field & gravity; historical references; drill for samples

2. Mine Minerals a. Surface Mining – when deposits are near surface

- General: 90% of rocks & minerals; 60% of coal done this way - Pros: Less expensive & dangerous - Cons: Overburden (left over soil & rock) must be removed; loss of topsoil & vegetation =

erosion; requires large amounts of land; visible tracts of land destroyed. - Solutions: add topsoil, plant vegetation (but, vegetation is often not the same as what

was removed) - Kinds:

i. Open-pit mine: big holes in ground (Cu ore, Fe ore, gravel, other stone) Problems: hard to remediate; water accumulation in bottom; no-fly zones

ii. Strip mining: bulldoze a thin parallel strips, burying each as you progress, unused debris called spoil piles (Coal, oil sands, phosphate rock – fertilizer). Problem: acid drainage (S + H2O H2SO4)

iii. Contour strip mining: strip mine on hilly land iv. Mountaintop removal: destroys entire mountains – removes coal w/out

subsurface mining (video clip from Killowat Ours). Can’t remediate. v. Dredging ocean floor: drag bucket along ocean floor

vi. Placer Mining: running water to isolate minerals b. Subsurface Mining – deposits deep under earth’s surface

i. mostly coal & valuable metals (Cu, Zn, Pb, Au, diamonds, coal) that are too deep for surface mining ii. dig deep tunnels /shafts along known mineral “veins” deep underground

iii. Pros: disturb far less land than surface mining (more hidden) iv. Cons: dangerous and more expensive than surface mining (black lung, CO exposure, chances for collapse)

1. Video Clips: Modern Marvels: Heavy Metals – Cu & Pb mining c. Environmental Problems:

i. Spoil Banks – ii. Tailings – toxic runoff as rainwater bonds to / reacts with newly exposed metals. Leaches into groundwater; runs

off into surface water iii. Newly exposed chemicals may bioaccumulate in animals iv. Quality of life near mining areas – flooding, noise pollution, risk of transportation accidents

3. Process & refine a. Smelting – melting ores @ high temperatures to help separate impurities from molten metals

D. Shell, SMHS 2013

Manganese nodules on Pacific Ocean

floor. Used for steel, alloys, etc.

b. Blast Furnace – ore, coke (coal), limestone react with heat to create ii. Purified molten iron (denser) – Fe ore + coke Fe(l) + CO2(g)

iii. Impurities (less dense) – limestone + impurities slag c. Cons: Dangerous gases released to air; energy & water intensive processes

4. Make into a product Legislation:

1. Surface Mining Control & Reclamation Act (1977) a. Mandates restoration efforts, requires companies to post bonds to cover reclamation costs

before mining can be approved b. Only for coal mining

2. General Mining Law of 1872-1996 a. established to encourage development of

western lands. b. They can stake land & buy for $2.

50-

$5.00

/acre and keep all profits (unlike timber, coal, oil, must pay 12.5% profit to feds)

c. No environmental protection (i.e. replacement of soil or vegetation; reestablishment of habitats)

d. >50 of the 10,000-50,000 abandoned mines in the US are Superfund sites

e. Cleanup estimated @ $12.5-17.5 billion f. 2000: Congress enacted new regulations

to protect taxpayers & environment i. GW Bush weakened the rules in

response to pressure from mining industry

3. Federal Strip-Mining Reclamation & Control Act 4. Antarctic Treaty (1961)

a. Limits activity in Antarctica to peaceful uses such as scientific studies 5. Convention on the Regulation of Antarctic Mineral Resource Activities (1980s)

a. Never ratified – would have permitted exploitation of Ant. minerals 6. Environmental Protection Protocol to the Antarctic Treaty (Madrid Protocol) (1990)

a. Moratorium on mineral exploration & development for >50 years b. Designated Antarctica & its marine ecosystem as a “natural reserve dedicated to peace and society”

7. UN Convention on the Law of the Sea (UNCLOS) (1994) a. Sets up general laws of ocean governance, with a later agreement discussing deep-sea mining. Never ratified by the US.

Solutions to Mining / Mineral supply problems: 1. Restoration / reclamation: restoring mining sites back to original condition

- Only partially effective - Removes buildings & other structures, replace overburden, fill in shafts, replant areas

2. Phytoremediation – using bacterial / plants to digest mining byproducts - Especially good for converting H2SO4 into H2S

3. Increasing Mineral Supply to Meet Demand a. reuse & recycle minerals

- 35% of metals in the US get recycled - 80% of the Pb used today comes from recycled car batteries - Recycled for metals: Electronics, appliances, vehicles, scrap, rechargeable batteries,

b. hope to find new reserves high quality ore in developing nations c. use new technology (biomining) to get minerals out of low-grade ore at reasonable $$ (ex: using cyanobacterial to extract Au) d. get Manganese (for steel) rich rocks off deep ocean floor bottom e. use substitutes like silicon & composite plastics (still negatives to this)

4. Sustainable manufacturing: minimizing waste during industrial processes 5. Industrial Ecology: extension of SM in which “wastes” for one industry are raw materials for another (ex: gypsum from coal

burning for sheet rock) 6. Dematerialization: decrease in size & weight of product over time as technology improves

Global Reserves

Problem: we produce very little in the US – are reliant on others Many countries go to war over resources