From there to here….

1. From there to here…. The Mining Process Please see the slide notes on for expanded information about the images on that slide.

2. Getting from there to here… • Many of the raw materials we need are found within the Earth. What needs to happen to get them and ensure that they are in a useable form? • Gravel and sand pits • Large rock slab quarries • Mines for materials such as gold, silver, copper, diamond, uranium, salt, and many others. Rock quarry. Diamond ring. • Focus on surface and underground mining, particularly the mining of metals in the U.S. Granite countertops

3. Getting from there to here… Ores need to be located (Exploration), obtained (Extraction), and then concentrated (Beneficiation/Smelting/Refining). Golden Sunlight Gold Mine mill. Blasting. Geological map. Waste rock revegetation. Surface and underground impacts will need to be remediated, the land reclaimed, and the mine safely closed once mining is completed.

4. Getting from there to here… Mining industry (in the United States) affected by several federal regulations to protect the environmental and human health. These were primarily initiated in the late 1960s. • Mines might need to adhere to additional regulations from states. • Many old mine sites (prior to regulation) are hazardous waste sites.

5. Exploration Estimates of the average composition of the Earth’s crust can be misleading. The composition of the Earth’s crust is not the same at all places. Chemical elements in Earth’s crust. Certain processes cause minerals to be concentrate in some areas.

6. Exploration Search for areas of higher concentrations for greater economic viability. Overall viability of a site for resource extraction can be influenced by a number of factors including: • Concentration of mineral (ore grade) • Depth to ore • Technology available • Potential environmental impact • Transportation and/or water needs • Regulations • Politics and/ or political boundaries • Social norms • Human health concerns Mining protest.

7. Exploration • Mining is very expensive. • Taking time and resources to explore is thus important. • Need to determine the location, size, depth, and the orientation/trend of the deposit. Surface expression (outcrop) of ore Land surface • Even if you know where it occurs at the surface, can you tell from this outcrop how extensive a deposit this ore might be? Which direction might it go as it gets deeper?

8. Exploration • Mining is very expensive. • Taking time and resources to explore is thus important. • Need to determine the location, size, depth, and the orientation/trend of the deposit. Surface expression (outcrop) of ore Land surface Continuation of ore body below the ground It could go this way . . .

9. Exploration • Mining is very expensive. • Taking time and resources to explore is thus important. • Need to determine the location, size, depth, and the orientation/trend of the deposit. Surface expression (outcrop) of ore Land surface Continuation of ore body below the ground Or maybe it goes this way . . .

10. Exploration • Mining is very expensive. • Taking time and resources to explore is thus important. • Need to determine the location, size, depth, and the orientation/trend of the deposit. Surface expression (outcrop) of ore Land surface Continuation of ore body below the ground Or maybe it goes this way. If you can get this information, it will help you decide where to mine, what direction to mine in, what technique is necessary, and the extent of the ore body!

11. Exploration Geoscientists use a combination of methods to find suitable mining locations. • Geologic maps (surface and cross sectional). • Results at other similar geological environments. • Visit potential site to complete field studies, which can include mapping, sampling, and chemical analyses. Surface Map Cross Sectional Map Geological map.

12. Exploration Check out this explanation on how seismics work: http://www.oerb.com/Default.aspx?tabid=274 • Enact “noninvasive” depth studies. Geoscientists will also: • Drill down through the surface to obtain samples. Example of a small drill rig used for mineral exploration. Note people on right for scale. Geoscientists examine core extracted by drill.

13. Extraction Usually begins after years of study once an appropriate site is found. • Two primary types of mining: • Surface (pit, strip, mountain top, etc.) mining • Underground (shaft) mining L Bingham Copper Mine, UT. Top: Sand mine. Bottom: Section of an underground mine.

14. Extraction: Surface Mining Bingham Copper Mine, Utah. • The largest mines are usually surface mines. • Can produce up to 150,000 tons of ore daily. • Heavy machinery and blasting procedures used. people Golden Sunlight Gold Mine, MT. Note people for scale. Floor (where people are standing) was set to be blasted later that day. Morenci Copper Mine, AZ

15. Extraction: Surface Mining • Often causes significant land disturbance. • Creation of much waste material. • ~2–3 tons of waste rock/ton ore Check out this video on blasting (~5 minutes): Three different copper/molybdenum surface mines, AZ. “The World’s Largest Recorded Mining Blast” from the Iron Ore Company of Canada. Blasting.

16. Extraction: Underground Mining • Includes use of tunnels and/or vertical shafts under the ground or into a mountain. • Usually smaller operations (i.e., a few 100,000 to 1 x 106 tons over the lifetime of a mine). This old lithograph of the mining of the Comstock silver deposit in the western Utah Territory (now Nevada) from 1877 gives a sense of the complex tunneling within underground mines. • Less land disturbance. • Less waste rock. • Waste rock can be moved to the surface or used to fill in mine areas no longer in use. Large equipment in an underground mine.

17. Extraction: Waste Rock Truck moving waste rock at Golden Sunlight Gold Mine, MT. Roads are also watered to prevent truck traffic from creating dust. • Waste Rock: Broken up rock that doesn’t contain the ore in high enough concentrations. • Overburden or surrounding rock. • Usually deposited close to mine. Shovel (on right side) that collects and dumps ore or waste rock into the truck (on left side) for transport. Note person for scale. Waste Rock (piled in between the hills) • Piles can cover hundreds to thousands of acres and be over 100 feet high. Right: Waste rock filling in valley between mountains at Golden Sunlight Mine, MT.

18. Extraction: Waste Rock • Smaller pieces have a greater total surface area. • More surfaces exposed to chemical weathering. • Can increase rate of weathering and erosion. • For some mining wastes, this is not a significant problem. Mining waste pile. • Presence of sulfide minerals can lead to contaminated or highly acidic streams, groundwater, and/or soil. • The United States has a legacy of hazardousmine waste rock areas. • Currently, more careful placement and monitoring of waste materials helps avoid future problems. Blasting!

19. Beneficiation Gold ore from Nevada. So, now we have some ore extracted, but it still looks something like this: Instead of this: Or this: Gold ingot from Toi Mine. Aluminum ingot. Beneficiation is the process throughwhich the desired minerals are concentrated. • The processes usedvary. • Function of mineral desired, mineral forms, host rock composition, etc. • Sometimes it’s possible to extract multiple commodities from the ores if they occur together (i.e., silver with copper).

20. Beneficiation: Crushing A conveyor belt (or a truck or a train) brings the ore to the crusher. A conveyor belt may bring the crushed ore to a mill. Crushed ore ready for the milling processat Golden Sunlight Gold Mine.

21. Beneficiation: Milling Steel balls to help crush ore into individual minerals • Milling: The crushed ore is powdered. • Placed into a rotating drum with steel rods or balls. • Water added. • Resultant rock slurry moves on to next step in the process (flotation or leaching). Rotating drum filled with crushed ore and steel balls Cell phone case for scale ~5 gallon bucket for scale Golden Sunlight Gold Mine, MT.

22. Beneficiation: Flotation • Slurry may be subject to a process called flotation. • Slurry + reagent + bubbles. • Desired mineral attaches to bubbles. • Bubbles float to top & are skimmed off. • Rest sinks to bottom. • Waste product called tailings. Schematic of one method of flotation. Pine oil is a reagent that can be used for copper beneficiation. Check out this video to see one method of flotation: http://www.abc.net.au/catalyst/stories/2533477.htm (~5 min)

23. Beneficiation: Flotation • Other processes may be used to further concentrate the desired mineral. • Extra water and/or reagent filtered off. • Activated carbon. • Electroplating. • Leaching with other reagents such as sodium cyanide. • Other processes.

24. Beneficiation: Tailings • Tailings often pumped into impoundments called tailing ponds. • Usually downhill from the mill. Above: Discharge of tailings slurry into tailings pond. • Can be thousands of acres in extent and a few hundred feet thick. Left: Satellite image of the Berkeley Pit and mining area with tailings and tailings pond (MT) (2006).

25. Beneficiation: Tailings Left: Copper-laden tailing water at the Anaconda Smelter Superfund site ~1992. • Sulfide minerals may be in high concentrations within the tailings. • Acidic conditions may develop. • Acid mine drainage (AMD). • Metals may be transported in the air and inhaled. • Contamination could be released quickly if dam fails. Above: Dried tailings become windblown at the Yankee Doodle tailings pond. • Plastic liners can be put down to prevent drainage of ponds and to cap them once full. • Water can be treated to neutralize it. • Legacy of issues surrounding older (unlined) tailing piles. Plastic liners put down to prevent tailings water from entering groundwater.

26. Beneficiation: Leaching • Leaching: The use of chemicals to dissolve desired metals and transport them, in solution, to a collection area. • Metals then precipitated out of solution. • Can take place in a vat or in large outdoor piles (heaps) or in the ground itself (in-situ). • Leach piles contain remaining mineral components plus chemical fluids. Many of the same environmental concerns as with the tailings/tailing ponds exist (plus additional leaching chemicals). • In heap leaching, the solution (sodium cyanide here) will percolate down through the pile and be collected at the bottom. Heap leaching at the Zortman-Landusky Mine (ca. 1996).

27. Smelting • Smelting:Separates the metal from the mineral through heating. • In presence of material known as a flux. • Desired mineral settles to the bottom of the melt. • Undesirables rise to top (slag). • Emissions from this process can be a source of pollution • sulfur dioxide, lead, particulates, and other gasses. • Increased regulation and improved technologies in the U.S. have resulted in a reduction in dangerous emissions. • Continued concentration of the metal may occur at a refinery. Smelting gold.

28. Mine Closure • Ore material will run out or become technologically or economically inaccessible. • Mine will close, sometimes filling with water. • Many mines closed prior to newer regulations left environmental problems. • Acid mine drainage and other water and soil contamination issues. • Mines today in the U.S. must meet different standards • Plan for human health and environmental protection during operations and after mine closure. Acidic mine tailings on the floodplain of Silverbow Creek in MT before remediation ~1998. • Include slope stabilization along with water and soil treatment to reduce contamination.

29. Reclamation • Reclamation: The restoration of land to either natural conditions or another useful purpose, often involving stabilizing soils and slopes in an area. • Treatment of the soil (or addition of new soil) is often necessary. • Can be completed as sections of the mine close or fill in. • Can assist with water flow patterns and water treatment. Revegetation of a waste rock area after third year. Revegetation of waste rock area at the Zortman-Landusky Mine, ca. 1996. Revegetation of a tailings area after the mine tailings had been removed.

30. Remediation • Remediation: The process of fixing, removing, or counteracting an environmental problem. • Often, the water leaving the mine must be remediated due to AMD. • Treatment can occur before the mine closes. Continued treatment in a wetland, where the plants help remediate the water. Anaconda Mine, ca. 1997. Acidic mine water flows along a channel containing limestone, to increase the pH (lower the acidity) prior to treatment in a wetland. Anaconda Mine, ca. 1997. One method of treating acidic mine water is to add alkaline material, causing iron and other metal to precipitate out of the water.

31. Additional Mineral Extraction Concerns Every step of the mineral extraction process is more complex than described here. The mining industry provides jobs (directly and indirectly tied to the mine), allows creation of products, pushes technology forward, and plays a key role in local and global economic systems. While regulations in the United States have become much more stringent since the 1970s, there are still environmental and health issues that the mineral extraction process incurs, and how to safely close a mine may not be clear.

32. Additional Mineral Extraction Concerns In addition to dealing with the clear legacy of historical mining in the water and soil from acid mine drainage and other contaminants, some other issues include: • The use of water, especially in arid regions. • Contamination of water through AMD, accidental spills, or other. • Mines that are not meeting federal or state regulations. • The impact on forests, including habitat destruction or alteration. • The use of public lands, such as in National Forests, for mineral extraction. • Worker health and safety, although this has been much improved since the 1980s (and earlier) labor laws. • Ground subsidence above underground mines. Collapse of land surface above underground mine in Australia.

33. Other Countries • Artisanal and small-scale mining (ASM) is common in some countries. • Mining enacted by individuals, small groups, or communities, often with limited technology. • Often in developing countries. • ~13 million people globally. • ~15–20% of global mineral (nonfuel) production. • In Ghana, 80% of the diamond production was from ASM. • May provide rural and impoverished community with improved local economy, but also concerns for lack of protections for workers, environment, and the community. • Not all countries have well-developed regulations (or do not effectively enforce those they have).

34. Glossary • Acid mine drainage (AMD): When sulfides (such as pyrite) oxidize and create acid. Not all mining activities create AMD, but it is often associated with metal mining because of the tendency for sulfides to be present in the rock. The acidity of the water can cause the soil to mobilize other metals into the water. • Beneficiation: Processes that separate the desired mineral from the rest of the rocks and minerals in the ore. • Electroplating: A process that uses an electrical current to encourage precipitation of the desired element. • Flotation: The beneficiation process in which bubbles of a reagent attract the desired mineral from the slurry and rise with it to the top of the mixture. This froth can then be removed for further concentration. • Leaching (in mining): The use of chemicals (such as sulfuric acid or sodium cyanide) to dissolve the desired metals and transport them in solution to a collection area. • Milling: The physical process of crushing and grinding the ore within the beneficiation process. • Mountain top mining/removal: A type of surface mining in which an entire mountain or mountain top is removed to obtain the ore within or underneath. • Ore:A material that occurs naturally and that contains a mineral(s) that can be extracted for a profit. • Ore grade: The concentration of the desired metal or element within the ore. • Reclamation: The restoration of land to either natural conditions or another useful purpose; this often involves the process of stabilizing soils and slopes in an area through the grading of slopes and use of vegetation. • Refining/Refinery: The final process in purifying an ore to the desired concentration after previous beneficiation. A refinery is where refining happens. • Remediation: The process of fixing, removing, or counteracting an environmental problem. • Slurry: A mixture of water and fine particulate material. • Smelting: The process of melting the beneficiated ore (concentrate) to reduce the impurities and concentrate the desired element. • Superfund: The program established to address hazardous waste sites with no owners. It enables the Environmental Protection Agency (EPA) to fund and perform clean-ups as well as locate the responsible party if still in existence. • Tailings: Waste material created from the beneficiation process. • Waste rock: Rock that must be moved in order to obtain the ore. This rock does not have a high enough concentration of the desired mineral to make it economically or technologically viable to extract.

35. Sources • Flotation:http://www.st-augustines.worcs.sch.uk/intranet/departments/sci2007a/Chemistry/NEWchemstart/metals%20stuff/copper%20stuff/copper%20extr/froth%20float%20diag.gif. • Global Acid Rock Drainage Guide.INAP: The International Network for Acid Prevention. http://www.gardguide.com/index.php/Main_Page. • Hentschel, T., Hruschka, F., and Priester, M. 2002. “Global Report on Artisanal & Small-Scale Mining.” Minerals, Mining and Sustainable Development, No. 70. 67 pages. http://pubs.iied.org/pdfs/G00723.pdf. • Hudson, T. L., Fox, F. D., and Plumlee, G. S. 1999. Metal Mining and the Environment. American Geological Institute. 68 pages. http://www.agiweb.org/environment/publications/metalsfull.pdf • Lide, D. R. 2000. CRC Handbook of Chemistry and Physics. CRC Press. • Tour of Golden Sunlight Mine(2012). • Salamon, M. (2010) “Miners Face Health Risks, Even on Good Days.” Live Science.http://www.livescience.com/11173-miners-face-health-risks-good-days.html. • Superfund: Basic Information.http://www.epa.gov/superfund/about.htm.

36. Acknowledgments • Thank you to the Golden Sunlight Mine (near Whitehall, MT), who in 2012 not only led us around on a tour but also allowed us to take pictures. • Thank you also to SERC and the Environmental Geology workshop in 2012 and in particular David Mogk for coordinating our tour of, and other related visits to and information about, Golden Sunlight Mine and also the Berkeley Pit in Butte, MT.