Mineral Extraction

1. Mineral Extraction

10. VOCABULARY TERMS • Ore- metal or mineral containing material extracted from the mine. Includes both metal and waste material that must be separated from the metal • Overburden- layer of rock and material lying over the ore. Surface mining removes this layer. • Spoils- Unwanted rock and other waste material produced during mining, dredging, quarrying, or excavation

11. Vocabulary con’t • Gangue – Unwanted material in the ore that will be removed during refining. • Tailings – Rock removed from ore during refining. • Smelting- process of refining an ore when desired metal is separated from other components of ore usually involving heat

12. Uneven distribution of Minerals • Minerals are unevenly distributed over 88 percent of the earth’s crust • Ores consist of concentrated accumulation of economically valuable minerals and metals • Countries must trade with one another to obtain important and valuable minerals and metals that are not found within its territories

13. Types of mining • Two kinds of mining take place on land: • SURFACE MINING • Strip Mining • Open-pit Mining • Mountaintop Removal • SUBSURFACE MINING

14. Area Strip Mining • Earth movers strip away overburden, and giant shovels remove the mineral deposit. • Leaves highly erodible hills of rubble called spoils • Often used in coal and Sand mining Figure 15-12

15. Contour Strip Mining • Used on hilly or mountainous terrain. • Unless the land is restored, a wall of dirt is left in front of a highly erodible bank called a highwall. Figure 15-13

16. OPEN-PIT MINING • Creates a large pit or hole in the ground. • Used when resource is close to the surface but extends beneath the surface horizontally and vertically (ex. Copper mines) Kennecott Bingham Canyon Mine near Salt Lake City, UT one of the largest open-pit mines in the world

17. Mountaintop Removal • Machinery or blasting removes the tops of mountains (overburden) to expose coal. • The resulting waste rock and dirt are dumped into the streams and valleys below. (Spoils) Figure 15-14

18. Surface mining • PLACER MINING • The process of looking for metal nuggets and precious stones in river sediments. • River water is used to separate heavier items like diamonds, tantalum, and gold, from lighter items like sand and mud. (ex. California gold rush)

19. SUBsurface mining • Used when resources are more than 100 meters (328 feet) below Earth’s surface. • Begins with a horizontal tunnel dug into the side of a mountain or feature. • Vertical shafts are drilled from the horizontal tunnel. • Elevators are used to bring miners down to the resource and back to the surface. • (ex. Coal, diamonds, and gold)

21. Mining Impacts • Metal ores are smelted or treated with (potentially toxic) chemicals to extract the desired metal. Figure 15-15

22. Impacts • Deposit of spoils and tailings could cause contamination and the blocking or changing the flow of rivers.

23. Impacts • Mining companies may not restore mining sites back to their original states. It then falls under CERCLA and federal Superfund dollars might be used.

24. Impacts • Surface and Subsurface mining can cause acid mine drainage, where lower pH water from the mine is stored above ground, and leakage can lower the pH of nearby soils and streams.

25. Impacts • Subsurface mining accidents are extremely dangerous to miners, while long term exposure to gases and particles can cause serious respiratory diseases.

26. Natural Capital Degradation Extracting, Processing, and Using Nonrenewable Mineral and Energy Resources Steps Environmental effects Mining Disturbed land; mining accidents; health hazards, mine waste dumping, oil spills and blowouts; noise; ugliness; heat Exploration, extraction Processing Solid wastes; radioactive material; air, water, and soil pollution; noise; safety and health hazards; ugliness; heat Transportation, purification, manufacturing Use Noise; ugliness; thermal water pollution; pollution of air, water, and soil; solid and radioactive wastes; safety and health hazards; heat Transportation or transmission to individual user, eventual use, and discarding Fig. 15-10, p. 344

27. Mining legislation • The Mining Law of 1872 (General Mining Act) – • http://en.wikipedia.org/wiki/General_Mining_Act_of_1872 • regulates the mining of silver, copper, and gold ore as well as fuels, including natural gas and oil, on federal lands. Written to encourage development in the western United States, it contains very few environmental protection provisions. It says federal land is open to mining claims by any citizen.

28. General Mining Act • Mining claim can give legal ownership of land • Abused: land used for other purposes • Very low royalties to federal government • Leaves toxic wastes behind • $32-72 billion est. to clean up older abandoned mines

29. Law • The Surface Mining Control and Reclamation Act of 1977 – http://en.wikipedia.org/wiki/Surface_Mining_Control_and_Reclamation_Act_of_1977 • regulates surface mining of coal and the surface effects of subsurface coal mining. The act mandates that land be minimally disturbed during the mining process and restored after mining is completed. It does NOT uniformly state what “Minimal” means.

30. Restoration Work • Fill in the hole or depression in the landscape. • Fill material must be relatively free of metals, acids, and other compounds and shaped to follow the preexisting contours. • The land must be replanted to re-create the ecosystem that existed before mining. 4. Properly completed reclamation makes the soil physically stable so that erosion does not occur and water infiltration and retention can proceed.

31. Fig. 12-20, p. 291

32. Stop & Think… • What were the most important ideas from this section of the lecture? Tell a partner – use your notes if needed. • Do you think the extraction methods for one are worse than the others? Why or why not? • Are mined materials considered renewable resources? Why or why not?